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May 12, 2005

A "Hidden" Biomarker in Prostate Cancer Cells - Researchers Find Way to Shake Loose

Topics: Prostate Cancer

Prostate cancer is expected to strike 232,090 men this year alone(ACS data), and of those, 30,350 are expected to die(about 13%). Although Prostate cancer is the second leading cause of cancer death in men, it is usually slow growing, is treatable, and survival rates are excellent when the disease is detected in its early stages. As for more advanced cases, it's almost a given that chemotherapy alone doesn't and immunotherapy alone might not be sufficient(there's also surgery and radiation), but if one could use both(or all), there might be more successes in treating patients whose cancer has spread.

Toward that end(concomitant chemo/immuno-therapy, or all), using a common chemotherapy agent, researchers at UCLA's Jonsson Cancer Center and the Department of Pathology and Laboratory Medicine have found a way to move an important biomarker expressed in prostate cancer, shaking it loose from one location in a cell - where it could not be accessed by blood - to another, easier to target area:

- Medical News Today
(...) The method discovered by the research team places the prostate-specific membrane antigen (PSMA) in a location on the cell that would allow blood-borne immunotherapies to access the biomarker, transforming it from a hidden target into an exposed one.

(...) "In prostate cancer cells, PSMA is expressed in the apical region of the cell membrane, which blood can't reach, so injection of immunotherapy into the bloodstream is not effective," said Rajasekaran, also an associate professor of pathology and laboratory medicine. "By using information from very basic studies about how the PSMA protein is targeted in these cells, we identified a way to redirect this protein within the cell. We found that if we disturbed hollow tubular structures called microtubules, part of the cell's framework, we were able to relocate PSMA from its 'hidden' location on the apical membrane to an accessible area in the basolateral surface."

(...) "These patients are getting chemotherapy anyway, and once we move the PSMA to a more accessible area on the prostate cancer cell, we might be able to use antibody-based immunotherapies as well, and they could be administered in the blood," \

(...) PSMA is an important biomarker for prostate cancer and its expression in the cell is proportional to the severity of the cancer - the more advanced the disease, the more PSMA is expressed.

(...) also showed for the first time in this study that prostate cancer cells maintain a well-differentiated morphology, with the PSMA hidden in the apical membrane of the cell, even when the cancer spreads outside the prostate - a fact that hadn't been proven before. Many researchers, in fact, had believed the opposite was true, Rajasekaran said. So discovering the mechanism of moving the PSMA to a more treatment accessible location on the cell could have ramifications for treating the sickest patients, those in whom the cancer has spread.

More ...

The study was conducted using prostate cancer cells lines and since the researchers plan to validate their findings first in animal models and then in human clinical trials, the results will not be available for up to four years.

Cross posted at Hyscience

Posted by Richard at May 12, 2005 8:51 AM

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