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Posted: Aug 01, 2012

Tumor cells change when put into a 'tight spot'

(Nanowerk News) “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.
Source: By Allison Chambliss, Johns Hopkins University
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