Decreased galectin-3 expression in prostate cancer. Prostate 44

BACKGROUND. Galectin-3 is a carbohydrate-binding protein whose level of expression has been shown to be correlated with metastatic potential in a number of different tumor types. The purpose of this investigation was to examine galectin-3 expression in several tumorigenic and nontumorigenic prostate cell lines and prostate tissue samples. METHODS. The expression of galectin-3 in cell lines and tissue samples was evaluated by tissue immunohistochemistry and Western blot analysis. RESULTS. Human cell lines PC-3M, PC-3, DU-145, PrEC-1, and MCF10A demonstrated the presence of galectin-3. Galectin-3 was not detected in TSU-pr1 and LNCaP by Western blot analysis. We furthered our studies by examining a series of human prostate tissue samples for expression of galectin-3. Overall, approximately 60–70 % of the normal tissue examined dem-onstrated heterogenous expression of galectin-3. In stage II tumors, however, there was a dramatic decrease in galectin-3 expression in both PIN and tumor sections, with only 10.5% (2/19) of these samples expressing this protein. Stage III tumors also demonstrated a de-creased expression of galectin-3, although this downregulation was not as dramatic, with 35% of PIN samples and 52 % of tumor tissue expressing galectin-3 (P < 0.01). CONCLUSIONS. These data demonstrate that galectin-3 is downregulated in prostate can-cer. The altered downregulation pattern of galectin-3 observed between tumor stages suggests different roles for galectin-3 in the progression of prostate cancer. Prostate 44:118–123, 2000