Recombinant human growth hormone activates JAK2-STAT3 pathway of human colon cells in vitro

Abstract

Objective To investigate the effect of recombinant human growth hormone (rhGH) on JAK2-STAT3 signaling pathway and on the growth of human colon cancer cells at different growth hormone receptor (GHR) expression status.Methods LOVO and HCT-8 cell lines were selected after the colon cancer cells were screened using flow cytometry according to the GHR expression status.The growth of human colon cancer cells after intervention with rhGH was detected by MTT assay.The proliferation index ( PI),cell cycle,and apoptosis were detected by flow cytometry.The expression of JAK2-STAT3 signaling pathway proteins was detected by Western blot.Results HCT-8 cell line showed positive GHR expression (59.6％),and LOVO cell showed negative GHR expression (3.5％).The growth rate of HCT-8 cells increased after rhGH treatment.Compared with the untreated HCT-8 cells,the rhGH-treated HCT-8 cells showed reduced apoptosis,elevated PI,and increased G2/Mphase cells ( P =0.0073).Western blot revealed that rhGH up-regulated the proteins of pJAK2,pSTAT3,VEGF,Cyclin D1,and Bcl-xL in HCT-8 cells.In contrast,no such changes were observed in LOVO cells treated with rhGH.Conclusions rhGH may promote the growth of HCT-8,the cell line of high GHR expression,and up-regulate the expression of a number of key nodes in JAK2-STAT3 signaling pathway.However,rhGH may not affect LOVO,the cell line of low GHR expression. Key words: Recombinant human growth hormone; Growth hormone receptor; Colon cancer; JAK2-STAT3 pathway