Phthalates promote prostate cancer cell proliferation through activation of ERK5 and p38

Prostate cancer is one of the most commonly diagnosed cancers in man. Studies have shown that phthalates may act as promoters in various types of cancer; however, the role of phthalates in prostate cancer has been rarely reported. The MAPK/AP-1 pathway is a vital regulator of cell proliferation in cancer. In this report we found that three typical phthalates, diethylhexyl phthalate (DEHP), Butyl benzyl phthalate (BBP) and Dibutyl phthalate (DBP), up-regulated cyclinD1 and PCNA, down-regulated P21, inducing proliferation of prostate cancer cells. Furthermore, we found that phthalates increased the expression of p-ERK5 and p-p38, along with upregulation of AP-1 (p-c-fos and p-c-jun). In studies with ERK5 and a p38 inhibitor, our data showed that downregulation of p-ERK5 or p38 inhibited phthalate-triggered cell proliferation. Taken together, findings from this study suggest that phthalates activate MAPK/AP-1 pathway and may potentially promote cell proliferation in prostate cancer, thus providing new insight into the effects and the underlying mechanism of phthalates on prostate cancer.