The effects of recombinant human GH on promoting tumor growth depend on the expression of GH receptor in vivo

Abstract

Cancer-related malnutrition is a mortal threat to gastric carcinoma patients. However, conventional nutrition treatment is not effective for recovery. Recombinant human GH (rhGH) is widely accepted clinically to treat severe malnutrition caused by non-malignant diseases, but not approved to treat malignant diseases due to the safety concern. To explore the safety of rhGH on gastric cancer, we assessed the effect of rhGH on two tumor-bearing mice modelsin vivoestablished by human gastric adenoma cell lines of SGC-7901 and MKN-45. VEGF expression in tumor tissues was detected using immunohistochemistry. The expression of GH receptor (Ghr),Jak-2,Stat3,Vegf, Hif-1α, Fgf, andMmp-2was measured by RT-PCR and protein expression of STAT3, phosphorylated STAT3, VEGF, HIF-1α, and MMP-2 was measured by western blotting. The immunocytochemistry results showed that the GHR expression of SGC-7901 was strongly positive (GHR+++), while GHR expression of MKN-45 was regarded as negative (GHR−). After 14 days of rhGH treatment in SGC-7901 (GHR+++) tumor-bearing mice, we found that the tumor growth was significantly increased, and the expressions of downstream factors and VEGF were increased. However, in MKN-45 (GHR−) tumor-bearing mice, tumor growth was not significantly increased by rhGH, but tumor-free body weight was increased especially in high-dose rhGH-treated group (P<0.05). These findings suggest that the level of GHR expression is a key target that influences the effectiveness of rhGH on promoting the growth of gastric cancer and angiogenesis. rhGH may promote the activation of tumor angiogenesis factors through the Jak-2–STAT3 pathway.