Researchers at Fox Chase Cancer Center in Philadelphia have identified two proteins in pancreatic cancer that may be potential targets for new, more specific drug therapies against this deadly disease. Medical oncologist Steven J. Cohen, M.D., presented the study today at the 40th Annual Meeting of the American Society of Clinical Oncology in New Orleans.
Cohen and his colleagues have identified increased levels of two enzymes, FAP (fibroblast activation protein) and FAK (focal adhesion kinase) in tumor samples and surrounding tissue of pancreatic adenocarcinoma specimens.
Fibroblast activation protein appears on connective tissue, or stromal fibroblasts, supporting the foundation (stroma) of various organs in the intestinal tract. This protein enhances the ability of a tumor to grow. Focal adhesion kinase not only promotes cell growth but also helps tumor cells migrate.
"Our hypothesis was that FAP and FAK would be overexpressed in pancreatic cancer and contribute to poor outcome," Cohen explained.
The researchers analyzed 29 tumor specimens from patients who had curative surgery, comparing them to normal and borderline tumor samples. Pancreatic cancer is characterized by a dense surrounding desmoplasia, or inflammatory reaction, which they hypothesized may contribute to the poor outcome in this disease. The role of FAP and FAK in cell growth and migration made them natural subjects for investigation.
"We found that FAP is overexpressed in over 90 percent of pancreatic adenocarcinomas, with greater expression in the fibroblasts surrounding the tumor than in the distant stroma," Cohen said. "Normal pancreas specimens did not have any FAP expression. "FAK was expressed in all tumor specimens and to a greater degree than in distant stroma. In the stromal tissue, there was a modest correlation between overexpression of FAK and FAP. This suggests that interaction between these proteins may contribute to the ability of pancreatic cancer to metastasize.
"Due to the heterogeneity of the patient samples, we did not see a clear impact of these proteins on clinical outcome such as survival," Cohen explained. "However, the selective overexpression of FAP and FAK compared to normal pancreas in and immediately adjacent to tumor suggests that these proteins are attractive novel therapeutic targets for pancreatic cancer." Cohen added that a number of animal models have been developed to study the effects of FAP on tumor growth.
"FAP promotes tumors in immunodeficient mice, but injecting antisera that blocks the activity of this enzyme inhibits tumor growth. Since targeting FAP appears promising in these preclinical models, we believe our study shows the feasibility of developing such targeted therapy for patients with pancreatic cancer."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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