The molecules behind metastasis
Greta Friar | Whitehead Institute
January 4, 2023

Many cancer cells never leave their original tumors. Some cancer cells evolve the ability to migrate to other tissues, but once there cannot manage to form new tumors, and so remain dormant. The deadliest cancer cells are those that can not only migrate to, but also thrive and multiply in distant tissues. These metastatic cancer cells are responsible for most of the deaths associated with cancer. Understanding what enables some cancer cells to metastasize—to spread and form new tumors—is an important goal for researchers, as it will help them develop therapies to prevent or reverse those deadly occurrences.

Past research from Whitehead Institute Member Robert Weinberg and others suggests that cancer cells are best able to form metastatic tumors when the cells are in a particular state called the quasi-mesenchymal (qM) state. New research from Weinberg and Arthur Lambert, once a postdoc in Weinberg’s lab and now an associate director of translational medicine at AstraZeneca, has identified two gene-regulating molecules as important for keeping cancer cells in the qM state. The research, published in the journal Developmental Cell on December 19, shows that these molecules, ΔNp63 and p73, enable breast cancer cells to form new tumors in mice, and illuminates important aspects of how they do so.

Most potent in the middle

Cells enter the qM state by undergoing the epithelial-mesenchymal transition (EMT), a developmental process that can be co-opted by cancer cells. In the EMT, cells transition from an epithelial state through a spectrum of more mesenchymal states, which allows them to become more mobile and aggressive. Cells in the qM state have only transitioned partway through the EMT, becoming more, but not fully, mesenchymal. This middle ground is perfect for metastasis, whereas cells on either end of the spectrum—cells that are excessively epithelial or excessively mesenchymal—lose their metastatic abilities.

Lambert and colleagues wanted to understand more about how cancer stem cells, which can seed metastases and recurrent tumors, remain in a metastasis-prone qM state. They analyzed how gene activity was regulated in those cells and identified two transcription factors—molecules that influence the activity of target genes—as important. One of the transcription factors, ΔNp63, appeared to most directly control cancer stem cells’ ability to maintain a qM state. The other molecule, p73, seemed to have a similar role because it can activate ΔNp63. When either transcription factor was inactivated, the cancer stem cells transitioned to the far end of the EMT spectrum and so were unable to metastasize.

Next, the researchers looked at what genes ΔNp63 regulates in cancer stem cells. They expected to find a pattern of gene regulation resembling what they would see in healthy breast stem cells. Instead they found a pattern closely resembling what one would see in cells involved in wound healing and regeneration. Notably, ΔNp63 stimulates EGFR signaling, which is used in wound healing to promote rapid multiplication of cells.

“Although this is not what we expected to see, it makes a lot of sense because the process of metastasis requires active proliferation,” Lambert says. “Metastatic cancer cells need both the properties of stem cells—such as the ability to self-renew and differentiate into different cell types—and the ability to multiply their numbers to grow new tumors.”

This finding may help to explain why qM cells are so uniquely good at metastasizing. Only in the qM state can the cells strongly stimulate EGFR signaling and so promote their own proliferation.

“This work gives us some mechanistic understanding of what it is about the quasi-mesenchymal state that drives metastatic tumor growth,” says Weinberg, who is also the Daniel K. Ludwig Professor for Cancer Research at the Massachusetts Institute of Technology.

The researchers hope that these insights could eventually contribute to therapies that prevent metastasis. They also hope to pursue further research into the role of ΔNp63. For example, this work illuminated a possible connection between ΔNp63 and the activation of dormant cancer cells, the cells that travel to new tissues but then cannot proliferate after they arrive there. Such dormant cells are viewed as ticking time bombs, as at any point they may reawaken. Lambert hopes that further research may reveal new insights into what causes dormant cancer cells to eventually gain the ability to grow tumors, adding to our understanding of the mechanisms of metastatic cancer.

Notes

Arthur W. Lambert, Christopher Fiore, Yogesh Chutake, Elisha R. Verhaar, Patrick C. Strasser, Mei Wei Chen, Daneyal Farouq, Sunny Das, Xin Li, Elinor Ng Eaton, Yun Zhang, Joana Liu Donaher, Ian Engstrom, Ferenc Reinhardt, Bingbing Yuan, Sumeet Gupta, Bruce Wollison, Matthew Eaton, Brian Bierie, John Carulli, Eric R. Olson, Matthew G. Guenther, Robert A. Weinberg. “ΔNp63/p73 drive metastatic colonization by controlling a regenerative epithelial stem cell program in quasi-mesenchymal cancer stem cells.” Developmental Cell, Volume 57, Issue 24,
2022, 2714-2730.e8, https://doi.org/10.1016/j.devcel.2022.11.015.

Sally Kornbluth

Education

  • Graduate: PhD, 1989, Rockefeller University
  • Undergraduate: BA, 1982, Political Science, Williams College; BS, 1984, Genetics, Cambridge University

Research Summary

Sally Kornbluth is President of MIT. Before she closed her lab to focus on administration, her research focused on the biological signals that tell a cell to start dividing or to self-destruct — processes that are key to understanding cancer as well as various degenerative disorders. She has published extensively on cell proliferation and programmed cell death, studying both phenomena in a variety of organisms. Her research has helped to show how cancer cells evade this programmed death, or apoptosis, and how metabolism regulates the cell death process; her work has also clarified the role of apoptosis in regulating the duration of female fertility in vertebrates.

Honors and Awards

  • Member, American Academy of Arts and Sciences, 2020
  • Member, National Academy of Inventors, 2018
  • Member, National Academy of Medicine, 2013
  • Distinguished Faculty Award, Duke Medical Alumni Association, 2013
  • Basic Science Research Mentoring Award, Duke University School of Medicine, 2012

Previous Administrative Leadership Positions

  • Provost, Duke University, 2014 – 2022
  • Vice Dean for Basic Sciences, Duke University School of Medicine, 2006 – 2014
Honoring Salvador Luria, longtime MIT professor and founding director of the MIT Center for Cancer Research

Koch Institute event celebrates the new MIT Press biography “Salvador Luria: An Immigrant Biologist in Cold War America.”

Kate Silverman Wilson | MIT Press
November 18, 2022

On Oct. 26, the Koch Institute for Integrative Cancer Research at MIT and the MIT Press Bookstore and the co-hosted a special event launching the new biography “Salvador Luria: An Immigrant Biologist in Cold War America,” by Rena Selya. The book explores the life of longtime MIT professor Salvador Luria (1912–1991), whose passion for science was equaled by his commitment to political engagement in Cold War America.

Luria was born in Italy, where the Fascists came to power when he was 10. He left Italy for France due to the antisemitic Race Laws of 1938, and then fled as a Jewish refugee from Nazi Europe, making his way to the United States. Once an American citizen, Luria became a grassroots activist on behalf of civil rights, labor representation, nuclear disarmament, and American military disengagement from the Vietnam and Gulf wars. Luria joined the MIT faculty in 1960 and was later the founding director of the MIT Center for Cancer Research (CCR), which is now the Koch Institute. Throughout his life he remained as passionate about his engagement with political issues as about his science, and continued to fight for peace and freedom until his death.

As inaugural director of the CCR, Luria secured status and funding as a National Cancer Institute basic cancer center to embark on what were then the vast unknowns of cancer biology, oversaw the physical transformation of a former chocolate factory into a research facility, recruited brilliant young scientists to form its founding faculty, and helped foster a culture of scientific rigor, innovation, and excellence that ultimately helped set the standard for the field.

MIT Institute Professor Philip Sharp and Daniel K. Ludwig Professor for Cancer Research Richard Hynes, both founding faculty at the CCR, participated in the special event. Speaking of the center’s earliest days, Hynes explained, “There was an awful lot of cooperation, which was key in the success of this institution. I credit that to Salva and David [Baltimore] in particular. And it’s continued. Because when you grow up in that sort of environment you learn to repeat it.” The discussion was moderated by Deborah Douglas, director of collections and curator, science and technology at the MIT Museum.

Blacklisted from federal funding review panels but awarded a Nobel Prize for his research on bacteriophages, Luria was as much an activist as a scientist. In this first full-length biography of Luria, Selya draws on extensive archival research; interviews with Luria’s family, colleagues, and students; and FBI documents obtained through the Freedom of Information Act to create a compelling portrait of a man committed to both science and society.

The event was fittingly held in the Salvador E. Luria Auditorium at the Koch Institute. Quoting Zella Hurwitz Luria, Luria’s wife, Selya said, “‘Let us celebrate Salva’s life, his humanity, his struggle for understanding life and its biophysical basis, his sense of deep and personal fulfillment at having helped to build what he believed to be the best biology department in the country, his driving need to see justice done, his struggle for a peaceful, democratic world, his real interest in knowing people unlike himself and his love of his family, friends and, coworkers.’ More than 30 years later, it is an honor and pleasure for me to do just that here in the Salvador E. Luria Auditorium.”

Nanosensors target enzymes to monitor and study cancer

By analyzing enzyme activity at the organism, tissue, and cellular scales, new sensors could provide new tools to clinicians and cancer researchers.

Bendta Schroeder | Erika Reinfeld | Koch Institute
November 2, 2022

Cancer is characterized by a number of key biological processes known as the “hallmarks of cancer,” which remodel cells and their immediate environment so that tumors can form, grow, and thrive. Many of these changes are mediated by specific genes and proteins, working in tandem with other cellular processes, but the specifics vary from cancer type to cancer type, and even from patient to patient.

Sensitive tools for measuring protein or gene expression, even on the single cell level, have helped researchers understand the different cell types present in a tumor’s microenvironment and how this composition changes after treatments. However, these assays don’t necessarily show which proteins are active or relevant to tumor progression, or allow clinicians to noninvasively monitor the progress of the disease or its response to treatment. A protein could be present in a cancer cell as a bystander, for example, but not an active participant in its cellular transformations. Enzymes, which catalyze biochemical reactions inside cells, may give a clearer picture of which genes or proteins to target at a particular time.

In work recently published in Nature Communications, researchers from the MIT Koch Institute for Integrative Cancer Research have developed a set of enzyme-targeting nanoscale tools to monitor cancer progression and treatment response in real time, map enzyme activity to precise locations within a tumor, and isolate relevant cell populations for analysis.

“We hope that this new suite of tools can be useful in the clinic and the lab alike,” says Sangeeta Bhatia, the John J. and Dorothy Wilson Professor of Health Sciences and Technology, professor of electrical engineering the computer science, and senior author of the study. “With further development, the nanosensors could be used by clinicians to tailor treatments to a patient’s specific cancer, and to monitor cancer progression and treatment response, while researchers could use them to better understand the molecular biology of cancer and develop new tools to diagnose, track, and treat the disease.”

Bhatia is also a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science. The study, conducted in collaboration with the laboratory of Tyler Jacks, was led by Ava Amini (Soleimany) ’16, a former graduate student from the Bhatia laboratory; and postdoc Jesse Kirkpatrick, also from the Bhatia lab.

Tracking tumors in real time

For several years, the Bhatia laboratory has been developing noninvasive urine tests for the detection of cancer, including colon, ovarian, and lung cancer. The tests rely on nanoparticles that interact with tumor proteins called proteases. Proteases are a type of enzyme that act as molecular scissors to cleave proteins and break them down into smaller components. Proteases help cancer cells escape from tumors by cutting through the extracellular network of proteins that holds cells in place.

The nanoparticles are coated with peptides (short protein fragments) that target cancer-linked proteases. When the nanoparticles arrive at the tumor site, the peptides are cut and release biomarkers that can be detected in the urine.

In the current study, the researchers tested whether they could use this technology not just to detect cancer, but to track the development of cancer and its response to treatments accurately and sensitively over time. The team created a panel of 14 nanoparticles designed to target proteases overexpressed in non-small cell lung cancer induced in a mouse model. These nanoparticles had been adapted to release barcoded peptides when they encounter dysregulated enzymes in the tumor microenvironment.

Each nanosensor was able to track different patterns of protease activity, which changed dramatically as the tumor progressed. After treatment with a lung cancer-targeting drug, the researchers were able to find signs tumor regression quickly, within just three days of administering treatment.

Cell maps and populations

While the existing nanosensor technique could be used to track tumor progression and treatment response in general, by itself, it could not shed any light on the specific cellular process at work.

“Like many of the tools available to assess molecular markers for cancer, our urine reporter treats the body like a black box,” says Kirkpatrick. “While we get some information about the state of the disease, we wanted to know more about the cells or proteins that are causing the disease to behave in a particular way.”

Having identified nanosensors of interest, researchers mapped where in the tumor microenvironment the enzymes acting on these sensors were active. They adapted their nanoprobes to leave behind fluorescent tags when they are cleaved from the nanosensor, assigning different tags to different proteases. After applying the nanoprobes to samples of lung tissue, they looked for patterns in how the tags were distributed.

One tag resulted in a curious spindle-like pattern that turned out to belong to the tumor vasculature. Researchers pinpointed the protease activity to specific types of cells: endothelial cells, which line blood vessels, and pericytes, which regulate vascular function and are actively recruited in angiogenesis — one of the archetypal hallmarks of cancer cell growth. Angiogenesis allows tumor cells to recruit existing blood vessels and stimulate new ones to form, in order to obtain the nutrients needed for tumor formation and progression.

Using their nanoprobes to label and sort cells based on their enzymatic activity, the team identified populations of cells associated with vasculature that displayed heightened expression of genes related to angiogenesis. The researchers also found evidence of signaling between pericytes and the endothelial cells that together comprise angiogenic blood vessels in vascular tissue.

Hallmark observations

In future work, the team seeks to identify the specific protease active in pericytes and dissect its role in angiogenesis. With this knowledge, they hope to develop formulations of therapies that can be delivered to patients to disrupt the recruitment and formation of blood vessels associated with tumor growth.

Ultimately, however, the team envisions panels of nanoprobes targeting several important features of cancer simultaneously and noninvasively in patients. Other hallmarks of cancer include proliferative signaling, the evasion of growth suppressors, genome instability, resistance to cell death, deregulated metabolism, and activation of invasion and metastasis. Because cancer alters protease activity across all of these processes, the team’s nanoprobes could be designed to target these different processes, with the aim of providing a comprehensive picture of tumor activity driving the disease. The approach could be used by researchers looking to investigate key biological phenomena in cancer models, as well as by clinicians seeking to monitor cancer progression noninvasively and select treatments for their patients.

The study was supported, in part, by the Virginia and D.K. Ludwig Fund for Cancer Research, the Koch Institute Frontier Research Program through a gift from Upstage Lung Cancer, the Koch Institute’s Marble Center for Cancer Nanomedicine, and Johnson & Johnson.

Introducing the Amon Award Winners
MIT Koch Institute
October 25, 2022

Cheers to the inaugural winners of the Koch Institute’s Angelika Amon Young Scientist Award, Alejandro Aguilera and Melanie de Almeida. The new award recognizes graduate students in the life sciences or biomedical research from institutions outside the U.S. who embody Dr. Amon’s infectious enthusiasm for discovery science.

Aguilera, a student at the Weizmann Institute of Science in Israel, has developed a platform for studying mammalian embryogenesis. De Almeida, who recently completed her doctoral work at the Research Institute of Molecular Pathology in Austria, develops CRISPR screens to explore cancer vulnerabilities and gene regulatory networks.

Aguilera and de Almeida will visit the Koch Institute in November to deliver scientific presentations to the MIT community and Amon Lab alumni.

Four from MIT receive NIH New Innovator Awards for 2022

Awards support high-risk, high-impact research from early-career investigators.

Phie Jacobs | School of Science
October 4, 2022

The National Institutes of Health (NIH) has awarded grants to four MIT faculty members as part of its High-Risk, High-Reward Research program.

The program supports unconventional approaches to challenges in biomedical, behavioral, and social sciences. Each year, NIH Director’s Awards are granted to program applicants who propose high-risk, high-impact research in areas relevant to the NIH’s mission. In doing so, the NIH encourages innovative proposals that, due to their inherent risk, might struggle in the traditional peer-review process.

This year, Lindsay Case, Siniša Hrvatin, Deblina Sarkar, and Caroline Uhler have been chosen to receive the New Innovator Award, which funds exceptionally creative research from early-career investigators. The award, which was established in 2007, supports researchers who are within 10 years of their final degree or clinical residency and have not yet received a research project grant or equivalent NIH grant.

Lindsay Case, the Irwin and Helen Sizer Department of Biology Career Development Professor and an extramural member of the Koch Institute for Integrative Cancer Research, uses biochemistry and cell biology to study the spatial organization of signal transduction. Her work focuses on understanding how signaling molecules assemble into compartments with unique biochemical and biophysical properties to enable cells to sense and respond to information in their environment. Earlier this year, Case was one of two MIT assistant professors named as Searle Scholars.

Siniša Hrvatin, who joined the School of Science faculty this past winter, is an assistant professor in the Department of Biology and a core member at the Whitehead Institute for Biomedical Research. He studies how animals and cells enter, regulate, and survive states of dormancy such as torpor and hibernation, aiming to harness the potential of these states therapeutically.

Deblina Sarkar is an assistant professor and AT&T Career Development Chair Professor at the MIT Media Lab​. Her research combines the interdisciplinary fields of nanoelectronics, applied physics, and biology to invent disruptive technologies for energy-efficient nanoelectronics and merge such next-generation technologies with living matter to create a new paradigm for life-machine symbiosis. Her high-risk, high-reward proposal received the rare perfect impact score of 10, which is the highest score awarded by NIH.

Caroline Uhler is a professor in the Department of Electrical Engineering and Computer Science and the Institute for Data, Systems, and Society. In addition, she is a core institute member at the Broad Institute of MIT and Harvard, where she co-directs the Eric and Wendy Schmidt Center. By combining machine learning, statistics, and genomics, she develops representation learning and causal inference methods to elucidate gene regulation in health and disease.

The High-Risk, High-Reward Research program is supported by the NIH Common Fund, which oversees programs that pursue major opportunities and gaps in biomedical research that require collaboration across NIH Institutes and Centers. In addition to the New Innovator Award, the NIH also issues three other awards each year: the Pioneer Award, which supports bold and innovative research projects with unusually broad scientific impact; the Transformative Research Award, which supports risky and untested projects with transformative potential; and the Early Independence Award, which allows especially impressive junior scientists to skip the traditional postdoctoral training program to launch independent research careers.

This year, the High-Risk, High-Reward Research program is awarding 103 awards, including eight Pioneer Awards, 72 New Innovator Awards, nine Transformative Research Awards, and 14 Early Independence Awards. These 103 awards total approximately $285 million in support from the institutes, centers, and offices across NIH over five years. “The science advanced by these researchers is poised to blaze new paths of discovery in human health,” says Lawrence A. Tabak DDS, PhD, who is performing the duties of the director of NIH. “This unique cohort of scientists will transform what is known in the biological and behavioral world. We are privileged to support this innovative science.”

MIT biologist Richard Hynes wins Lasker Award

Hynes and two other scientists will share the prize for their discoveries of proteins critical for cellular adhesion.

Anne Trafton | MIT News Office
September 28, 2022

MIT Professor Richard Hynes, a pioneer in studying cellular adhesion, has been named a recipient of the 2022 Albert Lasker Basic Medical Research Award.

Hynes, the Daniel K. Ludwig Professor for Cancer Research and a member of MIT’s Koch Institute for Integrative Cancer Research, was honored for the discovery of integrins, proteins that are key to cell-cell and cell-matrix interactions in the body. He will share the prize with Erkki Ruoslahti of Sanford Burnham Prebys and Timothy Springer of Harvard University.

“I’m delighted, and it’s a pleasure to be sharing it with them,” Hynes says. “It’s great for the field, and for the trainees who did much of the work.”

Hynes’ research focuses on proteins that allow cells to adhere to each other and to the extracellular matrix — a mesh-like network that provides structural support for cells. These proteins include integrins, a type of cell surface receptor, and fibronectins, a family of extracellular adhesive proteins. Integrins are the major adhesion receptors connecting the extracellular matrix to the intracellular cytoskeleton.

During embryonic development, cell adhesion is critical for cells to move to the correct locations in the embryo. Hynes’ work has also revealed that dysregulation of cell-to-matrix contact plays an important role in cancer cells’ ability to detach from a tumor and spread to other parts of the body, in a process known as metastasis.

“Professor Hynes’ contributions to the field of cancer biology, and more broadly, cellular biology, are numerous,” says Nergis Mavalvala, the Curtis and Kathleen Marble Professor of Astrophysics and the dean of the School of Science. “His investigations of fundamental biological questions — How do cells interact? How do they stick together? — changed how scientists approach cancer research and opened up avenues in developing potential therapeutics to disrupt metastatic disease.”

Born in Kenya, Hynes grew up in Liverpool, in the United Kingdom. Both of his parents were scientists: His father was a freshwater ecologist, and his mother a physics teacher. Hynes and all three of his siblings followed their parents into scientific fields.

“We talked science at home, and if we asked questions, we got questions back, not answers. So that conditioned me into being a scientist, for sure,” Hynes says.

After earning his bachelor’s and master’s degrees in biochemistry at Cambridge University, Hynes decided to head to the United States to continue graduate school. Colleagues at Cambridge suggested MIT, so he came to the Institute and earned his PhD in 1971. After doing a postdoc at the Imperial Cancer Research Fund Laboratories in London, he returned to MIT in 1975 as a faculty member in the Department of Biology and a founding member of MIT’s Center for Cancer Research (the predecessor of today’s Koch Institute).

Hynes began his career as a developmental biologist, studying how cells move to the correct locations during embryonic development. As a postdoc, he began studying the differences in the surface landscapes of healthy cells and tumor cells. This led to the discovery of a protein called fibronectin, which is often lost when cells become cancerous.

He and others found that fibronectin is part of the extracellular matrix, the network of proteins and other molecules that support cells and tissues in the body. When fibronectin is lost, cancer cells can more easily free themselves from their original location and metastasize to other sites in the body. Cells bind to the matrix through cell surface receptors known as integrins. In humans, 24 integrin proteins have been identified. These proteins help give tissues their structure, enable blood to clot, and are essential for embryonic development.

“These cell-matrix adhesion proteins hold us all together,” Hynes says. “If we didn’t have them, we’d be a pool of cells on the floor. And they’re contributors to lots of diseases: fibrosis, cancer, thrombosis, immune and autoimmune diseases. So, cell adhesion has become a huge field at both the basic science level and the therapeutic level.”

Since joining the MIT faculty, Hynes has also served as head and associate head of the Department of Biology, and as director of the Center for Cancer Research. He has also served as scientific governor of the Wellcome Trust in the United Kingdom, and as co-chair of National Academy committees establishing guidelines for stem cell and genome editing research.

His many awards include the Gairdner Foundation International Award, the Distinguished Investigator Award from the International Society for Matrix Biology, the Robert and Claire Pasarow Medical Research Award, the E.B. Wilson Medal from the American Society for Cell Biology and the Paget-Ewing Award, Metastasis Research Society. Hynes is also a member of the National Academy of Sciences, the National Academy of Medicine, the Royal Society of London, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences.

The Lasker Award comes with a $250,000 prize, which will be shared between the three recipients.

Through mentorship, a deeper understanding of brain cancer metabolism grows

As an MSRP-Bio student in the Vander Heiden lab, Alejandra Rosario helped to reveal how cancer cells maintain access to materials they need to grow.

Grace van Deelen | Department of Biology
September 22, 2022

Alejandra Rosario’s enthusiasm for research is infectious. When she talks about studying cancer cells, or the possibility of getting a PhD, her face lights up. “It’s something I’m really passionate about,” she says.

As a Bernard S. and Sophie G. Gould MIT Summer Research Program in Biology (BSG-MSRP-Bio) student this past summer in the lab of Matt Vander Heiden, MIT’s Lester Wolfe (1919) Professor of Molecular Biology, Rosario worked to understand cancer metabolism. MSRP-Bio is a 10-week, research-intensive summer program intended to introduce non-MIT undergraduates to a research career. Rosario, who is a senior at the University of Puerto Rico at Cayey this fall, was one of two MSRP-Bio students this year who were the first from their campus to attend the program. “It’s a really great opportunity for us,” she says.

Rosario had always been interested in research and understanding natural systems. As a child growing up in San Lorenzo, Puerto Rico, she was surrounded by nature, and got involved at a young age in environmental activism. She also has a special passion for the beach, which contributed to her eventual interest in science and, more specifically, in biology.

Medical connections

When her mother developed thyroid cancer, she focused on cancer research. To support her mother, Rosario tried to learn as much as possible about the type of cancer she was fighting, as well as the treatments available. She noticed the impact of basic cancer research on the therapies her mother was receiving.

As a result of her experience watching her mother battle cancer, too, Rosario has a special interest in translational medicine: working to determine how fundamental discoveries can have specific relevance to human disease treatment. “In cancer research,” she says, “small strides can be huge strides.”

Delving into a career in cancer research became a focus for Rosario, who sought out opportunities to advance her connections to the field. During a virtual conference held by the Society for the Advancement of Chicanos/Hispanics and Native Americans in Science, Rosario met MIT Department of Biology lecturer and science outreach director Mandana Sassanfar, who invited Rosario to visit MIT for a January workshop on computational skills. During the workshop, she met MIT professors, explored possible research ideas, and decided to apply to the MSRP-Bio program.

Rosario, who would like eventually to pursue a PhD or MD/PhD, was especially drawn to the Vander Heiden lab because of its focus on connecting research to medical applications. “I’m really fascinated about that connection, and how that works,” she says.

She especially liked the diversity of research happening in the lab, where projects range from cancer metabolism to genetics to stem cell research. “They’re all exploring different questions,” she says. “But at the end of the day, they all have conversations with each other and help each other out in a collaborative way.”

New insights into brain cancer

This summer, Rosario contributed to that diversity of research by continuing some of the core experiments of the Vander Heiden lab with a new cell line: glioblastoma, a type of brain cancer with a poor prognosis. The lab had never worked with this type of cancer before, so Rosario worked to understand its metabolism and process of cell division.

The main characteristic of cancer cells is that they divide very quickly. In order to do so, they need a lot of new material, like proteins, lipids, and nucleotides. A cancer cell has two options to obtain this new material: it can take it from the environment, or it can produce that new material itself. Glioblastoma occurs in the brain, a microenvironment that provides very little access to the materials necessary for cell division. In order to divide, then, glioblastoma cells must reprogram themselves in order to produce the materials necessary for growth.

Rosario’s research this summer sought to determine how glioblastoma cells survive in the environment of the brain by limiting the cells’ access to certain substances, like certain proteins or amino acids, and then measuring how the cells react. Understanding the cell’s reactions to such changes in the microenvironment could eventually inform cancer therapies.

“Our goal is to understand metabolically how these brain cancer cells are surviving everything we throw at them in order to possibly find a more specific target for treatment,” she says. Rosario presented her research in August in the MSRP-Bio poster session.

Shaped by mentorship

Overall, Rosario really enjoyed her experience as a summer researcher. The collaborative and open atmosphere in the lab, says Rosario, has helped her grow. For example, the lab holds occasional meetings called “Idea Club,” where researchers in the lab bring a question they’re struggling with or an idea they’re excited about, and other lab members give their input. “There’s a lot of scientific independence and curiosity,” says Rosario.

Rosario has especially enjoyed getting to know the graduate students in the lab, like Ryan Elbashir, a rising third-year doctoral student. Elbashir was also an MSRP-Bio student in 2018 and was one of the reasons Rosario chose the Vander Heiden lab. After a discussion with Elbashir about the importance of diversity in research, they formed a connection. “Alejandra is very inquisitive and comfortable around other people in the lab,” says Elbashir.

Rosario’s formal mentor, fourth-year MD/PhD student Sarah Chang, has also supported Rosario’s research goals by helping Rosario design research protocols and understand lab jargon. “Sarah’s been nothing but amazing,” says Rosario. “She’s teaching me how to think like a scientist.”

Rosario plans to build on the research she completed this summer in an MD/PhD program. She’d love to return to MIT or the Vander Heiden lab to carry out her future research and would like to continue to find ways to contribute to the development of cancer therapies. She’s very committed to studying cancer biology and wants to continue exploring the different sub-fields of cancer research during her senior year.

She plans to be a mentor to other young scientists, as well, and “pay it forward” to a new generation of underrepresented researchers. Mentoring, she says, creates a “chain reaction” of scientists supporting other scientists, which leads to better advances in research.

“By doing research and pursuing a question to the best of my abilities, I can impact as many people as possible,” she says.

Tracing a cancer’s family tree to its roots reveals how tumors grow

Family trees of lung cancer cells reveal how cancer evolves from its earliest stages to an aggressive form capable of spreading throughout the body.

Greta Friar | Whitehead Institute
May 5, 2022

Over time, cancer cells can evolve to become resistant to treatment, more aggressive, and metastatic — capable of spreading to additional sites in the body and forming new tumors. The more of these traits that a cancer evolves, the more deadly it becomes. Researchers want to understand how cancers evolve these traits in order to prevent and treat deadly cancers, but by the time cancer is discovered in a patient, it has typically existed for years or even decades. The key evolutionary moments have come and gone unobserved.

MIT Professor Jonathan Weissman and collaborators have developed an approach to track cancer cells through the generations, allowing researchers to follow their evolutionary history. This lineage-tracing approach uses CRISPR technology to embed each cell with an inheritable and evolvable DNA barcode. Each time a cell divides, its barcode gets slightly modified. When the researchers eventually harvest the descendants of the original cells, they can compare the cells’ barcodes to reconstruct a family tree of every individual cell, just like an evolutionary tree of related species. Then researchers can use the cells’ relationships to reconstruct how and when the cells evolved important traits. Researchers have used similar approaches to follow the evolution of the virus that causes Covid-19, in order to track the origins of variants of concern.

Weissman and collaborators have used their lineage-tracing approach before to study how metastatic cancer spreads throughout the body. In their latest work, Weissman; Tyler Jacks, the Daniel K. Ludwig Scholar and David H. Koch Professor of Biology at MIT; and computer scientist Nir Yosef, associate professor at the University of California at Berkeley and the Weizmann Institute of Science, record their most comprehensive cancer cell history to date. The research, published today in Cell, tracks lung cancer cells from the very first activation of cancer-causing mutations. This detailed tumor history reveals new insights into how lung cancer progresses and metastasizes, demonstrating the wealth of understanding that lineage tracing can provide.

“This is a new way of looking at cancer evolution with much higher resolution,” says Weissman, who is a professor of biology at MIT, a member of the Whitehead Institute for Biomedical Research, and an investigator with Howard Hughes Medical Institute. “Previously, the critical events that cause a tumor to become life-threatening have been opaque because they are lost in a tumor’s distant past, but this gives us a window into that history.”

In order to track cancer from its very beginning, the researchers developed an approach to simultaneously trigger cancer-causing mutations in cells and start recording the cells’ history. They engineered mice such that when their lung cells were exposed to a tailor-made virus, that exposure activated a cancer-causing mutation in the Kras gene and deactivated tumor suppressing gene Trp53 in the cells, as well as activating the lineage tracing technology. The mouse model, developed in Jacks’ lab, was also engineered so that lung cancer would develop in it very similarly to how it would in humans.

“In this model, cancer cells develop from normal cells and tumor progression occurs over an extended time in its native environment. This closely replicates what occurs in patients,” Jacks says. Indeed, the researchers’ findings closely align with data about disease progression in lung cancer patients.

The researchers let the cancer cells evolve for several months before harvesting them. They then used a computational approach developed in their previous work to reconstruct the cells’ family trees from their modified DNA barcodes. They also measured gene expression in the cells using RNA sequencing to characterize each individual cell’s state. With this information, they began to piece together how this type of lung cancer becomes aggressive and metastatic.

“Revealing the relationships between cells in a tumor is key to making sense of their gene expression profiles and gaining insight into the emergence of aggressive states,” says Yosef, who is a co-corresponding author on both the current work and the previous lineage tracing paper.

The results showed significant diversity between subpopulations of cells within the same tumor. In this model, cancer cells evolved primarily through inheritable changes to their gene expression, rather than through genetic mutations. Certain subpopulations had evolved to become more fit — better at growth and survival — and more aggressive, and over time they dominated the tumor. Genes that the researchers identified as commonly expressed in the fittest cells could be good candidates for possible therapeutic targets in future research. The researchers also discovered that metastases originated only from these groups of dominant cells, and only late in their evolution. This is different from what has been proposed for some other cancers, in which cells may gain the ability to metastasize early in their evolution. This insight could be important for cancer treatment; metastasis is often when cancers become deadly, and if researchers know which types of cancer develop the ability to metastasize in this stepwise manner, they can design interventions to stop the progression.

“In order to develop better therapies, it’s important to understand the fundamental principles that tumors adopt to develop,” says co-first author Dian Yang, a Damon Runyon Postdoctoral Fellow in Weissman’s lab. “In the future, we want to be able to look at the state of the cancer cells when a patient comes in, and be able to predict how that cancer’s going to evolve, what the risks are, and what is the best treatment to stop that evolution.”

The researchers also figured out important details of the evolutionary paths that cancer subpopulations take to become fit and aggressive. Cells evolve through different states, defined by key characteristics that the cell has at that point in time. In this cancer model the researchers found that early on, cells in a tumor quickly diversified, switching between many different states. However, once a subpopulation landed in a particularly fit and aggressive state, it stayed there, dominating the tumor from that stable state. Furthermore, the ultimately dominant cells seemed to follow one of two distinct paths through different cell states. Either of those paths could then lead to further progression that enabled cancers to enter aggressive “mesenchymal” cell states, which are linked to metastasis.

After the researchers thoroughly mapped the cancer cells’ evolutionary paths, they wondered how those paths would be affected if the cells experienced additional cancer-linked mutations, so they deactivated one of two additional tumor suppressors. One of these affected which state cells stabilized in, while the other led cells to follow a completely new evolutionary pathway to fitness.

The researchers hope that others will use their approach to study all kinds of questions about cancer evolution, and they already have a number of questions in mind for themselves. One goal is to study the evolution of therapeutic resistance, by seeing how cancers evolve in response to different treatments. Another is to study how cancer cells’ local environments shape their evolution.

“The strength of this approach is that it lets us study the evolution of cancers with fine-grained detail,” says co-first author Matthew Jones, a graduate student in the Weissman and Yosef labs. “Every time there is a shift from bulk to single-cell analysis in a technology or approach, it dramatically widens the scope of the biological insights we can attain, and I think we are seeing something like that here.”

A spectrum of cancer cells
Greta Friar | Whitehead Institute
April 11, 2022

Cancer is at its most deadly when it spreads and forms tumors in new tissues. This process, called metastasis, is responsible for the vast majority of cancer deaths, and yet there is still a lot that researchers do not know about how and when it happens. Whitehead Institute Founding Member Robert Weinberg, also the Daniel K. Ludwig Professor for Cancer Research at the Massachusetts Institute of Technology, studies the mechanisms behind metastasis. One such mechanism is a process called the epithelial-mesenchymal transition (EMT), which causes epithelial cells, which normally stick tightly together, to lose their cohesion, enabling them to move around and even invade nearby tissue. This EMT program also operates during embryonic development. Cancer cells can co-opt this process and use it travel from their original tumor site to distant tissues throughout the body. Some of the cancer cells that spread are able, on rare occasions, to form new tumors in these tissues—metastases—while the great majority of these cells remain dormant after entering the distant tissues.

New research from Weinberg and postdoc Yun Zhang shows that cells change in diverse ways through the actions of the EMT, which can influence whether cells are able to form new tumors after they spread. The work, published in Nature Cell Biology on April 11, 2022, also identifies two regulators of the EMT and shows that loss of each regulator leads to a different metastatic risk profile.

“Using triple negative breast cancer as a model, we are trying to go a bit deeper into understanding the molecular mechanisms that regulate the EMT, how cells enter into different EMT intermediate states, and which of these states contribute to metastasis,” Zhang says.

The EMT was originally imagined as a sort of binary switch, in which cells start out epithelial and become mesenchymal, much like a light switch being flicked from off to on. However, researchers are learning that the EMT works more like a dimmer switch that can be shifted along a spectrum of brightness. Cells that undergo the EMT usually end up in hybrid states between the epithelial and mesenchymal extremes. These cells in the middle of the spectrum, which have some characteristics of each extreme, are called “quasi-mesenchymal” cells, and it turns out that they–rather than cells that become fully mesenchymal–are the most capable of metastasizing and forming new tumors throughout the body.

Protected versus plastic cells

Weinberg and Zhang set out to better understand the EMT spectrum and what controls cells’ movement along it. First, they compared epithelial cells to each other and found that some were more plastic or prone to transitioning along the EMT spectrum than others. They also used the CRISPR gene editing tool to screen for genes that might be regulating the cells’ plasticity. If researchers can learn what makes a cell become quasi-mesenchymal—posing a high risk for metastasis—they might be able use this information, at some time in the future, to develop strategies to prevent cells from entering this high-risk state.

The CRISPR gene screen turned up a number of molecules that seemed to influence cells’ epithelial-mesenchymal plasticity. Two groups of these molecules had especially strong effects: PRC2, a complex that operates in chromosomes to silence or inactivate genes, and KMT2D-COMPASS, a complex that helps activate genes. Both complexes help to keep cells in a stable epithelial state. Loss of either complex makes cells more prone to moving along the EMT spectrum.

The researchers then determined how the loss of either complex enables the EMT. PRC2 normally silences several key EMT-related genes. When PRC2 is lost, those genes activate, which in turn sensitizes the cell to a signal that can trigger the EMT. The loss of KMT2D-COMPASS affects how well PRC2 can bind its targets, leading to the same signal sensitivity. In spite of the similar mechanisms at play, the loss of PRC2 versus KMT2D-COMPASS leads cells to transition to end up in different EMT states, an exciting finding for the researchers. Cells without KMT2D-COMPASS became fully mesenchymal, while cells without PRC2 became hybrid or quasi-mesenchymal. Consequently, cells without PRC2 were much more capable of metastasis than cells without KMT2D-COMPASS (or cells in which both complexes were active) in mouse models. When the researchers looked at historical data from breast cancer patients, they observed the same pattern: people with faulty PRC2 component genes had worse outcomes. These findings provide further evidence that cells in the middle of the EMT spectrum are most likely to metastasize.

This work supports the understanding of the EMT as a spectrum rather than a simple switch, and shows that different EMT regulators can program cells to transition to different parts of the EMT spectrum. Additionally, the finding that loss of PRC2 is linked to metastasis has implications for cancer drugs currently in development that work by inactivating PRC2. Benefits of the drugs may outweigh risks for patients with certain types of cancer for which PRC2 is an effective target. However, Weinberg and Zhang caution that researchers leading clinical trials of PRC2-targeting drugs should be careful about selecting patients and monitoring outcomes. In the types of cancer cells that the researchers looked at, even temporary PRC2 inactivation, such as from a therapy trial, was sufficient to trigger cells to become EMT hybrids with increased metastatic capacity.

Weinberg and Zhang intend to continue exploring the genes identified in their CRISPR screen to see if they can identify other hybrid states along the EMT spectrum, in which cells have different combinations of epithelial and mesenchymal features. They hope that by deepening their understanding of the gene expression profiles of cancer cells associated with different EMT trajectories, they can contribute to the development of therapies for people with potentially metastatic cancers.

“Understanding when and how cancer cells become able to form life-threatening metastases is crucial in order to help the many patients for whom this is a risk,” Weinberg says. “This work provides new insights into the mechanisms that enable cells to metastasize and the roles that different EMT programs can play.”