Effects of Exogenous Growth Hormone on Growth Hormone-Insulin-Like Growth Factor Axis of Human Gastric Cancer Cell

Aim: To study effects of recombinant human growth hormone (rhGH) on growth hormone-insulin-like growth factor axis (GH-IGFs) of human gastric cancer cell in vivo in order to reveal part mechanism of growth effects of rhGH on gastric cancer. Methods: Nude mice were randomly divided into control group, cisplatin (DDP) group, rhGH group and DDP + rhGH group after human gastric cancer xenograft model of node mice was successfully founded and drugs were used for 6 days. We investigated volume of tumor, inhibitory rate of tumor and cell cycle by slide gauge and flow cytometry. In addition, We also respectively investigated insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) of blood serum of nude mice, IGF-ImRNA, insulin-like growth factor-I receptor (IGF-IR) mRNA and IGFBP-3 mRNA of xenograft of nude mice by enzyme linked immunosorbent assay (ELISA) and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) on the first day of completing use of drugs later. Results: Tumor grew obviously slowly and tumor inhibitory rate obviously rose in DDP group and DDP + rhGH group compared with control group and rhGH group (p p p < 0.05). Expressions of IGF-I mRNA and IGF-IR mRNA were not obviously different in all groups. But expression of IGFBP-3 mRNA obviously increased in rhGH group, DDP group and DDP + rhGH group compared with control group;meanwhile, expression of IGFBP-3 mRNA also obviously increased in DDP + rhGH group compared with control group, DDP group and rhGH group. Conclusion: Our results indicated rhGH in short-time use did not improve proliferation of human gastric cancer cells and its mechanism was possible that rhGH in short-time use raised simultaneously IGF-I and IGFBP-3 of blood serum and increased IGFBP-3 mRNA, but degraded ratio of IGF-I and IGFBP-3 of blood serum in human gastric cancer cells.

Epithelial-mesenchymal transition contributes to malignant phenotypes of circulating tumor cells derived from gastric cancer

Circulating tumor cells(CTCs)are crucial to tumor metastasis,and they usually undergo epithelial-mesenchymal transition(EMT)in order to disseminate from the primary tumor.However,very little is currently known about the relationship between EMT and malignant phenotypes of CTCs in the context of gastric cancer.Therefore,this study aimed to investigate the contribution of EMT to malignant phenotypes of CTCs derived from gastric cancer cells.We xenografted MKN28 gastric cancer cells pretreated with transforming growth factor-beta 1(TGFβ-1)into nude mice by intravenous injection.Next,we isolated CTCs from the blood of nude mice by gradient centrifugation and found that CTCs derived from MKN28 cells pretreated with TGFβ-1 had a significantly increased viability and invasion ability compared to MKN28 cells without TGFβ-1 treatment.Immunocytochemical staining showed lower expression of E-cadherin and higher expression of N-cadherin,vimentin,and β-catenin in CTCs derived from MKN28 cells pretreated with TGFβ-1.Furthermore,the expression of Wnt3a,β-catenin,cyclin D1,and c-Myc was significantly higher in CTCs derived from MKN28 cells pretreated with TGFβ-1.Taken together,these findings suggest that TGFβ promotes EMT and malignant phenotypes of gastric cancer cells.Furthermore,the malignant phenotypes of gastric cancer cells induced by TGFβ are maintained in CTCs derived from these cells.Targeting EMT in CTCs is a new approach to the treatment of gastric cancer relapse and metastasis.