Konstantopoulos to present distinguished lecture on tumor cell migration

Biomedical Engineering 8 5 x 11 4-7Biomedical Engineering 8 5 x 11 4-7Biomedical Engineering 8 5 x 11 4-7Professor and Chair of the Department of Chemical and Biomolecular Engineering, Konstantinos Konstantopoulos will present a distinguished lecture for the Department of Biomedical Engineering on Monday, April 7 at 4 p.m. in the Mason Hall Auditorium on the Homewood campus of Johns Hopkins University.  His talk. “Joining Forces with Biology: A Bioengineering Perspective on Tumor Cell Migration,” will reveal some of his laboratory’s current findings on metastasis. The talk is free and open the Johns Hopkins University community. Refreshments follow the lecture.

Here’s the abstract of his talk:

“Understanding the mechanisms of cell migration is a fundamental question in cell, developmental and cancer biology. Unraveling key, physiologically relevant motility mechanisms is also crucial for developing technologies that can control, manipulate, promote or stop cell migration in vivo. Much of what we know about the mechanisms of cell migration stems from in vitro studies using two-dimensional (2D) surfaces. Cell locomotion in 2D is driven by cycles of actin protrusion, integrin-mediated adhesion and myosin-dependent contraction. A major pitfall of 2D assays is that they fail to account for the physical confinement that cells  encounter within the physiological tissue environment. The seminar will challenge the conventional wisdom regarding cell motility mechanisms, and show that migration through physically constricted spaces does not require beta1 integrin dependent adhesion or myosin contractility. Importantly, confined migration persists even when filamentous actin is disrupted. This seminar will also discuss a novel mechanism of confined cell migration based on an osmotic en

Cancer spreads through ‘Rock’ and ‘Rho’

n low oxygen conditions, breast cancer cells form structures that facilitate movement, such as filaments that allow the cell to contract (green) and cellular ‘hands’ that grab surfaces to pull the cell along (red). Credit: Daniele Gilkes

In low oxygen conditions, breast cancer cells form structures that facilitate movement, such as filaments that allow the cell to contract (green) and cellular ‘hands’ that grab surfaces to pull the cell along (red).
Credit: Daniele Gilkes

ROCK1 and RhoA genes found partly to blame for cancer metastasis. Gregg Semenza, co-director of the Johns Hopkins Physical Sciences-Oncology Center (PS-OC), led a team that made the discovery. The following comes from a Johns Hopkins press release:

Biologists at The Johns Hopkins University have discovered that low oxygen conditions, which often persist inside tumors, are sufficient to initiate a molecular chain of events that transforms breast cancer cells from being rigid and stationary to mobile and invasive. Their evidence, published online in Proceedings of the National Academy of Sciences on Dec. 9, underlines the importance of hypoxia-inducible factors in promoting breast cancer metastasis.

“High levels of RhoA and ROCK1 were known to worsen outcomes for breast cancer patients by endowing cancer cells with the ability to move, but the trigger for their production was a mystery,” says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine at the Johns Hopkins University School of Medicine and senior author of the article. “We now know that the production of these proteins increases dramatically when breast cancer cells are exposed to low oxygen conditions.”

To move, cancer cells must make many changes to their internal structures, Semenza says. Thin, parallel filaments form throughout the cells, allowing them to contract and cellular “hands” arise, allowing cells to “grab” external surfaces to pull themselves along. The proteins RhoA and ROCK1 are known to be central to the formation of these structures.

Moreover, the genes that code for RhoA and ROCK1 were known to be turned on at high levels in human cells from metastatic breast cancers. In a few cases, those increased levels could be traced back to a genetic error in a protein that controls them, but not in most. This activity, said Semenza, led him and his team to search for another cause for their high levels.

What the study showed is that low oxygen conditions, which are frequently present in breast cancers, serve as the trigger to increase the production of RhoA and ROCK1 through the action of hypoxia-inducible factors.

“As tumor cells multiply, the interior of the tumor begins to run out of oxygen because it isn’t being fed by blood vessels,” explains Semenza. “The lack of oxygen activates the hypoxia-inducible factors, which are master control proteins that switch on many genes that help cells adapt to the scarcity of oxygen.” He explains that, while these responses are essential for life, hypoxia-inducible factors also turn on genes that help cancer cells escape from the oxygen-starved tumor by invading blood vessels, through which they spread to other parts of the body.

Daniele Gilkes, Ph.D., a postdoctoral fellow at the PS-OC and lead author of the report, analyzed human metastatic breast cancer cells grown in low oxygen conditions in the laboratory. She found that the cells were much more mobile in the presence of low levels of oxygen than at physiologically normal levels. They had three times as many filaments and many more “hands” per cell. When the hypoxia-inducible factor protein levels were knocked down, though, the tumor cells hardly moved at all. The numbers of filaments and “hands” in the cells and their ability to contract were also decreased.

When Gilkes measured the levels of the RhoA and ROCK1 proteins, she saw a big increase in the levels of both proteins in cells grown in low oxygen. When the breast cancer cells were modified to knock down the amount of hypoxia-inducible factors, however, the levels of RhoA and ROCK1 were decreased, indicating a direct relationship between the two sets of proteins. Further experiments confirmed that hypoxia-inducible factors actually bind to the RhoA and ROCK1 genes to turn them on.

The team then took advantage of a database that allowed them to ask whether having RhoA and ROCK1 genes turned on in breast cancer cells affected patient survival. They found that women with high levels of RhoA or ROCK1, and especially those women with high levels of both, were much more likely to die of breast cancer than those with low levels.

“We have successfully decreased the mobility of breast cancer cells in the lab by using genetic tricks to knock the hypoxia-inducible factors down,” says Gilkes. “Now that we understand the mechanism at play, we hope that clinical trials will be performed to test whether drugs that inhibit hypoxia-inducible factors will have the double effect of blocking production of RhoA and ROCK1 and preventing metastases in women with breast cancer.”

Other authors of the report include Lisha Xiang, Sun Joo Lee, Pallavi Chaturvedi, Maimon Hubbi and Denis Wirtz of the Johns Hopkins University School of Medicine.

This work was supported by grants from the National Cancer Institute (U54-CA143868), the Johns Hopkins Institute for Cell Engineering, the American Cancer Society and the Susan G. Komen Breast Cancer Foundation.

Studying cells in 3D, the way it should be

When scientists experiment on cells in a flat Petri dish, it’s more been a matter of convenience than anything that recapitulates what that cell experiences in real life. Johns Hopkins professor Denis Wirtz for some time has been growing and studying cells three dimensions, rather than the traditional two dimensions. And pretty much, he’s discovered that a lot of what we think we know about cells is dead wrong.

cancer-in-3d-impact_0

Cell in 3D. Image by Anjil Giri/Wirtz Lab

In this recent article by Johns Hopkins writer Dale Keiger, you will discover what Wirtz has discovered through his investigations. Furthermore, you will find out about the man behind these revolutionary ideas that are turning basic cell biology upside-down, as well as challenge a lot of what we thought we understood about diseases like cancer.

Wirtz directs the Johns Hopkins Physical-Sciences Oncology Center and is associate director and co-founder of Johns Hopkins Institute for NanoBioTechnology. He recently launched the Center for Digital Pathology. He is a the Theophilus Halley Smoot professor of chemical and biomolecular engineering.

You can read the entire magazine article “Moving cancer research out of the Petri dish and into the third dimension” online here at the JHU Hub.

Picture this: Transcription ‘twists’ toward metastasis

Mol Cancer Res Cover (1)

Molecular Cancer Research Cover

Researchers associated with Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins School of Medicine and School of Public Health have published “The Twist Box Domain Is Required for Twist1-induced Prostate Cancer Metastasis,” in a recent issue of the journal Molecular Cancer Research. An illustration related to the work graced the cover.

Authors on the paper include co-lead authors Rajendra P. Gajula and Sivarajan T. Chettiar,  as well as Russell D. Williams, Saravanan Thiyagarajan, Yoshinori Kato, Khaled Aziz, Ruoqi Wang, Nishant Gandhi, Aaron T. Wild, Farhad Vesuna, Jinfang Ma, Tarek Salih, Jessica Cades, Elana Fertig, Shyam Biswal, Timothy F. Burns, Christine H. Chung, Charles M. Rudin, Joseph M. Herman, Russell K. Hales, Venu Raman, Steven S. An and corresponding author Phuoc T. Tran

Here is an abstract of their paper and caption for the cover:

“Twist1 plays key roles during development and is a master transcriptional regulator of the epithelial-mesenchymal transition that promotes cancer metastasis. We demonstrated three important findings in prostate cancer cells that overexpress Twist1: (1) Twist1 leads to elevated cytoskeletal stiffness and traction forces at the migratory edge of cell collections; (2) The Twist box domain is required for Twist1-induced pro-metastatic in vitro properties and in vivo metastases; and (3) Hoxa9 is a novel Twist1 transcriptional target that is required for Twist1-induced pro-metastatic phenotypes. Targeting the Twist box domain and Hoxa9 may effectively limit prostate cancer metastatic potential.”

Visit the journal here: Molecular Cancer Research 

 

Tumor cells change when put into a ‘tight spot’

Konstantinos Konstantopoulos addresses audience at 2012 NanoBio Symposium. Photo by Mary Spiro/JHU

“Cell migration represents a key aspect of cancer metastasis,” said Konstantinos Konstantopoulos, professor and chair of the Department of Chemical and Biomolecular Engineering at Johns Hopkins University. Konstantopoulos was among the invited faculty speakers for the 2012 NanoBio Symposium.

Cancer metastasis, the migration of cancer cells from a primary tumor to other parts of the body, represents an important topic among professors affiliated with Johns Hopkins Institute for NanoBioTechnology. Surprisingly, 90 percent of cancer deaths are caused from this spread, not from the primary tumor alone. Konstantopoulos and his lab group are working to understand the metastatic process better so that effective preventions and treatments can be established. His students have studied metastatic breast cancer cells in the lab by tracking their migration patterns. The group has fabricated a microfluidic-based cell migration chamber that contains channels of varying widths. Cells are seeded at one opening of the channels, and fetal bovine serum is used as a chemoattractant at the other opening of the channels to induce the cells to move across. These channels can be as big as 50 µm wide, where cells can spread out to the fullest extent, or as small as 3 µm wide, where cells have to narrowly squeeze themselves to fit through.

A current dogma in the field of cell migration is that actin polymerization and actomyosin contractility give cells the flexibility they need to protrude and contract across a matrix in order to migrate. When Konstantopoulos’s students observed cells in the wide, 50 µm-wide channels, they saw actin distributed over the entirety of the cells, as expected. They also observed that when the cells were treated with drugs that inhibited actin polymerization and actomyosin contractility, they did not migrate across the channels, also as expected.

However, when the students observed cells in the narrow, 3 µm-wide channels, they were surprised to see actin only at the leading and trailing edges of the cells. Additionally, the inhibition of actin polymerization and actomyosin contractility did not affect the cells’ ability to migrate.

“Actin polymerization and actomyosin contractility are critical for 2D cell migration but dispensable for migration through narrow channels,” concluded Konstantopoulos. The data challenged what many had previously believed about cell migration by showing that cells in confined spaces did not need these actin components to migrate.

These findings are indeed important in the context of cancer metastasis, where cells must migrate through a heterogeneous environment of both wide and narrow areas. Konstantopoulos’s data gives a better mechanistic understanding of the different methods cancer cells use to migrate in diverse surroundings.

Future studies in the Konstantopoulos lab will focus on how tumor cells decide which migratory paths to take. INBT-sponsored graduate student Colin Paul has developed an additional microfluidic device that contains channels with bifurcations. He hopes to determine what factors guide a cell in one direction versus another. The Konstantopoulos lab hopes to continue to understand exactly how tumor cells migrate so that new therapies can eventually be developed to stop metastasis.

Story by Allison Chambliss, a Ph.D. student in the Department of Chemical and Biomolecular Engineering with interests in cellular biophysics and epigenetics.

Watch a video related to this research here.

Konstantopoulos reported these findings in October 2012 The Journal of the Federation of American Societies for Experimental Biology.  Read the article online here.

 

Engineering in Oncology Center will probe forces that cause cancer to spread

Center director Denis Wirtz and associate director Greg Semenza

The Johns Hopkins Engineering in Oncology Center at INBT will be headed by Denis Wirtz, left. Gregg Semenza will serve as associate director. (Photo by Will Kirk/JHU)

Researchers from the Johns Hopkins Institute for NanoBioTechnology have been awarded a $14.8 million grant from the National Cancer Institute to launch a research center aimed at unraveling the physical underpinnings that drive the growth and spread of cancer. The new Johns Hopkins Engineering in Oncology Center at INBT includes 11 Johns Hopkins faculty members affiliated with the INBT and four investigators from partner universities. The project’s participants say that they hope this new line of research will lead to never-before-considered approaches to cancer therapy and diagnostics.

The Johns Hopkins center is one of 12 being launched by the National Cancer Institute to bring a new cadre of theoretical physicists, mathematicians, chemists and engineers to the study of cancer. During the five-year initiative, the NCI’s Physical Sciences-Oncology Centers will take new, nontraditional approaches to cancer research by studying the physical laws and principles of cancer; evolution and evolutionary theory of cancer; information coding, decoding, transfer and translation in cancer; and ways to deconvolute cancer’s complexity.

“By bringing a fresh set of eyes to the study of cancer, these new centers have great potential to advance, and sometimes challenge, accepted theories about cancer and its supportive microenvironment,” said NCI Director John E. Niederhuber. “Physical scientists think in terms of time, space, pressure, heat and evolution in ways that we hope will lead to new understandings of the multitude of forces that govern cancer, and with that understanding, we hope to develop new and innovative methods of arresting tumor growth and metastasis.”

The NCI, which is an agency of the National Institutes of Health, will allocate the Johns Hopkins-based Engineering in Oncology Center’s funding over five years. As the name of the center suggests, the researchers will look at how physical sciences play a role in the way cancer spreads, commonly called metastasis.

Wirtz, Semenza to direct EOC

Denis Wirtz, a professor of chemical and biomolecular engineering in the Whiting School of Engineering, will direct the center, and Gregg L. Semenza, a leading researcher at the School of Medicine, will serve as associate director.

“Metastasis is a highly coordinated, multistep process,” Wirtz said. “Cancer cells break free from a primary tumor, penetrate into the bloodstream, evade host defenses, stick to the interior walls of blood vessels and travel to other organs, where they set up new cancer cell colonies. During this cascade of events, tumor cells push on and are pushed by mechanical forces within their microenvironment. Cells translate those mechanical forces into biochemical signals that affect cell growth and function. If we can gain a better understanding of this process, we may find new and better ways to treat cancer.”

Wirtz, who is principal investigator, also serves as associate director of the university’s Institute for NanoBioTechnology, a cross-divisional institute launched in May 2006 with 185 Johns Hopkins faculty members who are using nanoscience to answer questions in medicine, the basic sciences and public health.

The new cancer center will similarly draw on Johns Hopkins researchers with diverse expertise to study the role of physical forces involved in the development and spread of cancer.

“Mechanical forces inside the body, such as shear exerted by blood flowing through blood vessels, typically destroy the millions of cancer cells that are constantly shed from tumors,” Wirtz said. “But the ‘fittest’ of cancer cells survive these Darwinian-like selective pressures and may become the culprits that spread cancer. Little is known about the effect of mechanical forces on the regulation of cancer cell growth. That is what the Engineering in Oncology Center and the National Cancer Institute want to find out. The results should point us to therapies and diagnostic tools that complement existing genetic or molecular treatments.”

In a congratulatory letter to Wirtz concerning the new center, Johns Hopkins President Ronald J. Daniels wrote, “This is a terrific achievement that highlights the value of interdisciplinary research and collaboration across the university, and the increasing importance this approach will have in the coming years. I am especially proud to see Johns Hopkins lead the way in this manner. … Not only will you be embarking into a new realm of scientific collaboration, you will be, at the same time, establishing Johns Hopkins as a leading center of excellence in this field. The ongoing fight against cancer demands new ideas, perspectives and approaches, and that is precisely what you are creating in [this] center.”

Semenza, the associate director, is affiliated with the School of Medicine’s departments of Pediatrics, Medicine, Oncology and Radiation Oncology, and the McKusick-Nathans Institute of Genetic Medicine. He is the C. Michael Armstrong Professor in Medicine and founding director of the Vascular Program at the school’s Institute for Cell Engineering. He also has ties to the School of Medicine’s Department of Biological Chemistry and to the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins.

Center will focus on three primary research aims

Semenza and Sharon Gerecht, an assistant professor of chemical and biomolecular engineering, will lead one of the center’s three key research projects related to how cancer spreads. They will focus on analyzing the makeup and physical properties of the extracellular matrix, the three-dimensional scaffold in which cells live.

“Normal cells live in a flexible scaffold, but cancer cells create a rigid scaffold that they climb through to invade normal tissue,” Semenza said. “We will study how this change occurs and how it is affected by the amount of oxygen to which cancer cells are exposed. Our studies have shown that cancer cells are deprived of oxygen, which incites them to more aggressively invade the surrounding normal tissues where oxygen is more plentiful. Hypoxia-inducible factor 1 controls the responses of cancer cells to low oxygen, and we have recently identified drugs that block the action of HIF-1 and inhibit tumor growth in experimental cancer models.”

The center’s second key research project teams Wirtz with Greg D. Longmore, a cancer cell biologist at Washington University in St. Louis. The two will study the physical basis for cancer cell adhesion and de-adhesion and how it increases the likelihood that cancer cells will break free, move into the bloodstream and migrate to other tissues. “Cancer cells are able to modulate proteins on the surface almost like a protein ‘brake’ that allows them to adhere or de-adhere in response to mechanical forces,” Wirtz said.

The center’s third primary research project will be led by Konstantinos Konstantopoulos, professor and chair of the Whiting School’s Department of Chemical and Biomolecular Engineering, and Martin L. Pomper, who holds appointments in the School of Medicine’s Department of Radiology and the Kimmel Cancer Center. These two researchers will investigate the effects of fluid mechanical forces at different oxygen tension microenvironments on tumor cell signaling, adhesion and migration.

“Fluid flow in and around tumor tissue modulates the mechanical microenvironment, including the forces acting on the cell surface and the tethering force on cell-substrate connections,” Konstantopoulos said. “Cells in the interior of a tumor mass experience a lower oxygen tension microenvironment and lower fluid velocities than those at the edges in proximity with a functional blood vessel, and are prompted to produce different biochemical signals. These differential responses affect tumor cell fate—that is, whether a cell will live or die, and whether it will be able to detach and migrate to secondary sites in the body.”

All three projects will combine experimental and computational/theoretical results to develop a better picture of how these mechanical forces influence cancer metastasis.

An educational component for graduates and postdoctoral fellows

In addition to the research component, the Engineering in Oncology Center will have a multidisciplinary training program for predoctoral students and postdoctoral fellows. The training program will be co-directed by Peter Searson, INBT’s director and the Joseph R. and Lynn C. Reynolds Professor in the Department of Materials Science and Engineering, and the School of Medicine’s Kenneth W. Kinzler, who is among the world’s most-cited cancer biologists and who serves as co-director of the Johns Hopkins Ludwig Center.

Other Johns Hopkins researchers affiliated with the Engineering in Oncology Center are Sean X. Sun, associate professor in the Department of Mechanical Engineering, and two faculty members from the Department of Biomedical Engineering: Kevin Yarema, associate professor, and Aleksander S. Popel, professor.

In addition to Longmore, the researchers from other institutions who will participate in the Johns Hopkins-based center are Timothy C. Elston, a theoretical and computational biophysicist at the University of North Carolina, Chapel Hill; Yiider Tseng, an experimental biophysicist and biochemist at the University of Florida; and Charles W. Wolgemuth, a theoretical and computational biophysicist at the University of Connecticut.

The center will incorporate two dedicated research facilities, also known as cores. The EOC Imaging Core will be established under the existing Integrated Imaging Center on the Homewood campus. J. Michael McCaffery, associate research professor of biology in the Krieger School of Arts and Sciences, will oversee the Imaging Core and facilitate imaging resources for EOC faculty. Searson will oversee the EOC Microfabrication Core, which will assist researchers in making the needed materials and devices for their experiments.

The Engineering in Oncology Center will be administered by the Institute for NanoBioTechnology, located on the Homewood campus, where research will occur in renovated laboratory facilities. Training and collaboration with investigators located at the four other research universities on the grant will occur through periodic onsite visits and via Web-based platforms.

Related Links:

National Cancer Institute’s Physical Sciences-Oncology Centers program

Johns Hopkins Engineering in Oncology Center at INBT

Johns Hopkins Institute for NanoBioTechnology

Podcast: Nanotech method to study cell detachment could lead to improved cancer therapies

Peter Searson

Peter Searson

Cancer spreads from organ to organ when cells break free from one site and travel to another. Understanding this process, known as metastasis, is critical for developing ways to prevent the spread and growth of cancer cells. Peter Searson, Reynolds Professor of Materials Science and Engineering in the Whiting School of Engineering and director of the Institute for NanoBioTechnology, led a team of engineers who have developed a method to specifically measure detachment in individual cells.

The method, which uses lab-on-a-chip technology, allows researchers to observe and record the exact point when a cell responds to electrochemical cues in its environment and releases from the surface upon which it is growing. Better knowledge of the biochemistry of cell detachment could point the way to better cancer therapies. In this “Great Ideas” podcast, Elizabeth Tracey, communications associate for the School of Medicine, interviews Searson about this current research.

“…We know that processes like cell detachment are important in cancer metastasis, where cells become detached from tumors…” Peter Searson

Click here to listen:  Great Ideas Podcast: Peter Searson

Related links:

You can watch a video and read more about Searson’s method of studying cell detachment here.

Peter Searson’s INBT profile page.

This podcast was originally posted to the Johns Hopkins University “Great Ideas” web page. To view the original posting, click here.