The influence of matriptase-2 on prostate cancer in vitro: a possible role for β-catenin

The type II transmembrane serine proteases (TTSPs) are a family of cell surface proteolytic enzymes contributing to a number of processes, such as tumour invasion and metastasis. Within the TTSPs, matriptase-2 is a relatively newly identified member and this protease has been shown to play a key role in cancer progression. β-catenin has long been regarded as an oncogene. The deregulation of the β-catenin signalling pathway plays a significant role in the progression and possibly the development of cancer. However, little is known about the role of matriptase-2 in prostate cancer. This study aimed to examine the correlation between matriptase-2 and β-catenin. Matriptase-2 was knocked down in the normal prostate cells, PZHPV7 and PNT2C2, using a ribozyme transgene targeting matriptase-2. The altered cells were used in a number of in vitro experiments designed to investigate the involvement of matriptase-2 with β-catenin and to further characterise its function. The knockdown of matriptase-2 had no effect on cell growth or adhesion but significantly reduced cell motility (PZHPV7 cells, p<0.001; PNT2C2 cells, p=0.001 vs. respective control cells) and invasive capability (PZHPV7 cells, p=0.001; PNT2C2 cells, p=0.007). The knockdown also caused a large increase in β-catenin protein expression at the cell membrane in PZHPV7 and PNT2C2 cells and a decrease in PC3 cells overexpressing matriptase-2, but did not affect the mRNA levels. Matriptase-2 may have an important impact on prostate cancer progression. The data gained from this study suggest that matriptase-2 protects against the development and progression of prostate cancer by regulating the motility and invasive capabilities of prostate cancer cells. Matriptase-2 also reduces the levels of β-catenin at the cell membrane. As β-catenin is highly involved in the regulation of cellular processes, including motility and invasion, the reduction of β-catenin expression by matriptase-2 may be a possible mechanism by which matriptase-2 functions.