Hypoxia has been previously linked to the development of both benign prostatic hyperplasia and prostate cancer. This study investigated the effect of maspin, an extracellular matrix (ECM) tumor suppressor, on the apoptotic response of prostate cancer cells to hypoxia. Gene expression profiling of human benign and malignant prostate epithelial cells after exposure to hypoxia or normoxia revealed dramatic changes in ECM regulators. Maspin was found to be overexpressed in response to hypoxia in prostate cancer cells, but not in benign prostate cells. To dissect the contribution of maspin to tumor cell responses within a hypoxic microenvironment, we used maspin-overexpressing DU-145 human prostate cancer cells. Exposure to hypoxic conditions (1% O2) led to a significant increase in apoptosis in the DU-145 maspin cells, compared to DU-145 neo-transfectants without a significant effect on cell migration. This enhanced sensitivity to hypoxia-induced apoptosis leads to a significant suppression of tumor growth and tumor vascularityin vivoby targeting Akt and focal adhesion kinase activation. Our findings implicate maspin in prostate cancer cell response to hypoxia via recruitment of intracellular signaling partners. This study may have significance in the identification of maspin-driven therapeutic targeting in advanced metastatic prostate cancer.
Oncogene (2008) 27, 7171-7179; doi:10.1038/onc.2008.321; published online 20 October 2008