56649

TMPRSS4

TMPRSS4 is a novel type II transmembrane serine protease found at the cell surface that is highly expressed in pancreatic, colon and gastric cancer tissues. However, the biological functions of TMPRSS4 in cancer are unknown. Here we show, using reverse transcription-PCR, that TMPRSS4 is highly elevated in lung cancer tissues compared with normal tissues and is also broadly expressed in a variety of human cancer cell lines. Knockdown of TMPRSS4 by small interfering RNA treatment in lung and colon cancer cell lines was associated with reduction of cell invasion and cell-matrix adhesion as well as modulation of cell proliferation. Conversely, the invasiveness, motility and adhesiveness of SW480 colon carcinoma cells were significantly enhanced by TMPRSS4 overexpression. Furthermore, overexpression of TMPRSS4 induced loss of E-cadherin-mediated cell-cell adhesion, concomitant with the induction of SIP1/ZEB2, an E-cadherin transcriptional repressor, and led to epithelial-mesenchymal transition events, including morphological changes, actin reorganization and upregulation of mesenchymal markers. TMPRSS4-overexpressing cells also displayed markedly increased metastasis to the liver in nude mice upon intrasplenic injection. Taken together, these studies suggest that TMPRSS4 controls the invasive and metastatic potential of human cancer cells by facilitating an epithelial-mesenchymal transition; TMPRSS4 may be a potential therapeutic target for cancer treatment.

TMPRSS4 is a novel type II transmembrane serine protease that is highly expressed on the cell surface in pancreatic, thyroid and other cancer tissues, although its oncogenic significance and molecular mechanisms are unknown. Previously, we have shown that TMPRSS4 promotes invasion, migration and metastasis of human tumor cells by facilitating an epithelial-mesenchymal transition (EMT). In this study, we explored the molecular basis underlying TMPRSS4-mediated effects. We show that multiple downstream signaling pathways, including focal adhesion kinase (FAK), extracellular signal-regulated kinase (ERK), Akt, Src and Rac1, are activated by TMPRSS4 expression and that FAK signaling and ERK activation are required for TMPRSS4-induced invasiveness and EMT, including cadherin switch. Inhibition of PI3K or Src reduced invasiveness and actin rearrangement mediated by TMPRSS4 without restoring E-cadherin expression. Downregulation of E-cadherin was required for TMPRSS4-mediated effects but was not sufficient to induce EMT and invasion. TMPRSS4 induced integrin alpha5 expression and its signal transduction, leading to invasiveness and EMT accompanied by downregulation of E-cadherin. Functional blocking confirmed that integrin alpha5beta1 is a critical signaling molecule that is sufficient to induce TMPRSS4-mediated effects. Immunohistochemical analysis showed that TMPRSS4 expression was significantly higher in human colorectal cancer tissues from advanced stages than in that of early stage. Furthermore, upregulation of TMPRSS4 was correlated with enhanced integrin alpha5 expression. These observations implicate integrin alpha5 upregulation as a molecular mechanism by which TMPRSS4 induces invasion and contributes to cancer progression.

Transmembrane protease serine 4 (TMPRSS4) is a novel type II transmembrane serine protease that is overexpressed in various types of human cancers and has an important function in cancer progression. However, there is a paucity of data available regarding the biological effects of TMPRSS4 on breast cancer (BC) cells and the underlying mechanisms. In this study, expression of TMPRSS4 in BC tissues was detected by immunohistochemistry. The relationship between TMPRSS4 expression and clinicopathological characteristics as well as prognosis was evaluated. The effects of TMPRSS4 on cell proliferation, migration and invasion were investigated in BC cell lines in vitro. Additionally, RT-qPCR and western blot analysis were used to determine the expressions of epithelial-mesenchymal transition (EMT) biomarkers and TMPRSS4 in BC cell lines. We found that TMPRSS4 was overexpressed in BC tissues and its expression level was closely correlated with tumor size, histological grade, lymph node metastasis, clinical stage as well as poor survival (all P<0.05) and could be recognized as an independent prognostic factor for BC patients. Overexpression of TMPRSS4 promoted the proliferation, migration and invasion of BC cells in vitro. Moreover, TMPRSS4 knockdown significantly enhanced the expression of E-cadherin and claudin-1 and inhibited the expression of vimentin and Slug, indicating suppression of EMT. Our results suggest that TMPRSS4 plays a crucial role in the progression of BC. Moreover, TMPRSS4 overexpression promoted the proliferation, invasion and migration of BC cells by possibly inducing EMT. To conclude, TMPRSS4 may be a potential therapeutic target for cancer treatment.