Human kallikrein 7 induces epithelial-mesenchymal transition-like changes in prostate carcinoma cells: a role in prostate cancer invasion and progression.

Human tissue kallikrein 7 (hK7), a chymotrypsin-like secreted serine protease, catalyzes the degradation of intercellular adhesive structures in the cornified layer of the skin, leading to desquamation. Thus, hK7 is implicated in cancer invasion and metastasis. Although hK7 is highly expressed in prostate tissues, its biological role in prostate cancer progression is poorly understood. In the current study, we established an hK7-expressing cell model for prostate tumors by stably transfecting prostate carcinoma 22RV1 and DU145 cells with an expression vector encoding hK7. We found that there were no obvious differences in cell proliferation between cells overexpressing hK7 and cells transfected with empty vector (p>0.05). Intriguingly, a Matrigel invasion assay revealed that hK7 remarkably increased the migration and invasion of prostate cancer cells (p<0.01). Furthermore, hK7 induced epithelial-mesenchymal transition-like changes in prostate carcinoma cells, as evidenced by scattered cellular growth, mesenchyma-like morphology, and up-regulated expression of vimentin, a mesenchymal marker. These novel findings suggest that hK7 plays an important role in mediating prostate cancer progression and that hK7 promotes invasion and metastasis, at least in part, through inducing the epithelial-mesenchymal transition of prostatic carcinoma cells.