Overexpression of GSTP1 promotes colorectal cancer cell proliferation, invasion and metastasis by upregulating STAT3

Background. The abnormal expression of glutathione S-transferase P1 (GSTP1) is associated with the progression of several tumor types. However, its role and molecular mechanism in the progression of colorectal cancer (CRC) are largely unknown. Objectives. To examine the effect of GSTP1 in CRC and determine its possible mechanisms. Materials and methods. In the present study, immunohistochemistry (IHC) and the quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis were used to detect the expression of GSTP1 and signal transducer and activator of transcription 3 (STAT3) in CRC tissues. Western blotting was applied to detect the expression of GSTP1 and proteins of the Janus kinase (JAK)-STAT3 pathway in different CRC cell lines. The interaction and co-localization of GSTP1 and STAT3 were detected using co-immunoprecipitation (co-IP) and immunofluorescence (IF) in the SW620 cell line. Results. A positive correlation was identified between the expression of GSTP1 and STAT3 in human CRC tissues. The overexpression of GSTP1 promoted the proliferation, invasion and metastasis of CRC cells by up regulating STAT3. The GSTP1 and STAT3 can directly bind to and regulate each other. The interaction between them is regulated by the upstream gene called F-box only protein 8 (FBX8). Conclusions. The present study demonstrated that GSTP1 could enhance the expression of STAT3 to promote the proliferation, invasion and metastasis of CRC cells, which provides a potential therapeutic target for the clinical treatment of CRC.