Effect of rhGH on JAK2-STAT3 signal pathway after GHR was down-regulated by siRNA in gastric cancer cell / 药学学报

ABSTRACT

To investigate the effect of recombinant human growth hormone (rhGH) on JAK2-STAT3 pathway and the growth of gastric cancer cell lines at different GHR expression status, the eukaryotic expression vector targeting human GHR (pGPU6/GFP/Neo-shGHR and pGPU6/GFP/Neo-scramble) was constructed and transfected into MGC803 cells by Lipofectamine 2000. Stable expressive cell lines were obtained by G418 screening. The expression of GHR was analyzed by Western blotting. After being stimulated with rhGH, cell growth was detected by MTT assay. Cell cycle and apoptosis were examined by flow cytometry. The components of JAK2/STAT3 signaling pathway were detected by Western blotting. There is no significant difference of GHR expression between MGC803 and pGPU6/GFP/Neo-scramble-transfected cells (named as MGC803-NC) (P > 0.05). Compared with MGC803, the GHR expression in pGPU6/GFP/Neo-shGHR-transfected cells (named as MGC803-shGHR) decreased significantly (protein decreased 50%). The cells were treated with rhGH at 0, 150 and 300 ng x mL(-1), the growth rate of MGC803 and MGC803-NC increased significantly, PI and the number of G2/M phase cells all increased significantly, and apoptosis decreased significantly. Western blotting revealed that the expression of pJAK2 and pSTAT3 was up-regulated after being treated with rhGH in MGC803 and MGC803-NC cells. In contrast, similar change was not observed in MGC803-shGHR cells. Knockdown of GHR gene may decrease the sensitivity of gastric cancer cells to rhGH, and down-regulating of components of the expression of JAK2/STAT3 signaling pathway may be the potential mechanisms.