Elasticity of cells may help researchers to identify cancer.

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Cancer cells are softer and more elastic than healthy cells, and measuring cell stiffness may provide a new way to diagnose cancer, according to two researchers from the University of California, Los Angeles.

The researchers measured the stiffness of live metastatic cancer cells using atomic force microscopy (AFM), a nanomechanical tool used to study surfaces at high resolution, from the pleural fluid of patients with suspected lung, breast, or pancreatic cancers. The researchers used the ultra-sharp tip of the atomic force microscope to apply force to single cells and measured the resistance because cancer cells have less resistance to such pressure than normal cells do. They found that metastatic cancer cells are more than 70% softer, with a standard deviation more than five times narrower, than the benign cells that line the body cavity. In addition, different cancer types were found to display a common stiffness.

Researchers believe that unlike normal cells, cancer cells are more flexible and can move through holes and spaces easily, which is how they enter the bloodstream and spread to other organs. Previous in vitro nanomechanical studies on architectural changes in cultured cell lines had demonstrated that changes in cell stiffness affected the way the cells spread; however, no ex vivo mechanical studies of cancer cells had been conducted.

Recent progress in the study of cancer cell motility and invasion has generated greater understanding of the mechanical properties involved in malignant transformation and cell mechanics, which have emerged as important markers for cytoskeletal organization, cell adhesion, and spreading. Cell stiffness may be associated with these cytoarchitectural changes.

AFM was able to identify cancer cells undetected by conventional morphologic analysis. The technique is 1,000 times more accurate than the most sensitive traditional tests for cancer, and researchers hope that it will be able to warn doctors of tumors that are spreading.

Unlike biologists who usually focus on the chemical rather than physical properties of cells, scientists have begun applying the tools of materials science and engineering to their cell research. This is the first time a mechanical analysis of patient tumor cells has been reported. The results show that nanomechanical analysis correlates well with immunohistochemical testing currently used for detecting cancer and that nanomechanical tests of cancer cells might be incorporated into future cancer diagnosis and treatment.

The researchers plan to test how cancer drugs affect cell stiffness in future studies. They believe that cell stiffness may help researchers determine how aggressive a patient's cancer is and predict whether it will respond to particular therapies.

Cross, S.E., Jin, Y., Rao, J., & Gimzewski, J.K. (2007). Nanomechanical analysis of cells from cancer patients. Nature Nanotechnology, 2(12), 780-783.

Deborah McBride, RN, MSN, CPON[R], Contributing Editor

Contributing Editor Deborah McBride, RN, MSN, CPON[R], is a nurse at the Ka1iser Permanente Oakland Medical Center and a faculty member at Samuel Merritt College in Oakland, CA.