Effect of PTPRB on metastasis of colorectal carcinoma and induction of epithelial-mesenchymal transition.

Abstract

e15099 Background: Colorectal cancer (CRC) is one of the most common and lethal cancers worldwide. Metastasis and recurrence are believed to be responsible for limiting long-term survival of patients with CRC. Protein tyrosine phosphatase, receptor type B ( PTPRB) belongs to the protein tyrosine phosphatase family. Multiple studies have previously demonstrated that dysregulation of PTPRB function and expression has been shown to correlate with carcinogenesis and tumor progression in multiple cancer types. Methods: In this study, we used CRC cell lines to explore the expression of PTPRB and to analyze the biological function of PTPRB protein. Surgical tumor specimens were collected for immunohistochemical staining to evaluate PTPRB expression.Real-time polymerase chain reaction (PCR) and western blot analysis were used to confirm genes and proteins of interest, respectively. Results: PTPRB is expressed at significantly higher levels in CRC tissues compared to adjacent non-tumor tissues and in CRC cell lines with high metastasis potential. PTPRB knockdown decreased the number of invasive CRC cells in a vitro wound healing model, and also reduced tumor metastasis in vivo. Conversely, PTPRB overexpression decreased E-cadherin expression and promoted vimentin expression, while PTPRB knockdown had the opposite effect. Hypoxic conditions induced EMT and promoted metastasis in CRC cells, but these effects were eliminated by PTPRB knockdown. EMT blockade via TWIST1 knockdown inhibited the migration and invasiveness of CRC cells, and even increased PTPRB expression could not reverse this effect. Conclusions: PTPRB is upregulated in CRC and overexpression of PTPRB promotes the metastasis of CRC. Moreover, our study revealed the effect of PTPRB on promoting EMT, as reflected in increased vimentin and decreased E-cadherin expression. PTPRB is a novel therapeutic target for the treatment of CRC.