Impact of growth hormone on the pathways of IGF-I and IGF-II in pancreatic cancer and in small intestine mucosa of the host

Objective To study the impact of exogenous growth hormone (GH) on the levels of insulin-like growth factor-Ⅰ and -Ⅱ (IGF-Ⅰ, -Ⅱ) of the pancreatic cancer tissue and the small intestine mucosa of the host. Methods In situ hybridization was performed on pancreatic cancer cell lines (SW-1990) and inoculation tumor of the host to determine the location of the mRNA transcript encoding IGF R-Ⅰ,-Ⅱ. Athymic nude Balb/c mice were inoculated with SW-1990 cells. After inoculated tumors have become palpable, animals were randomized to receive GH (4 mg/kg once daily for 2 weeks) versus saline control. After the animals were killed at time point, tissues (tumor and small intestine) were rapidly incised for subsequent immune blotting analysis. Results Strong IGF R-Ⅰ,-Ⅱ mRNA hybridization signal could be detected in pancreatic cancer cell. There was no statistically significant difference between the level of IGF-Ⅰ, Ⅱ in the tumor of the GH and NS groups after 1 hours of GH injection (P>0.05). GH augmented the expression of IGF-Ⅰ(1 h : 0.33±0.05, P<0.05 ; 2 h : 0.34±0.04, P<0.05 ; 6 h:0.34±0.05, P<0.05), -Ⅱ(1 h : 0.36±0.05, P<0.05) in the small intestine mucosa of the host. Conclusions The expression of IGF-Ⅰ, Ⅱ in the small intestine mucosa of the host was elevated by GH, but not in the inoculation tumor in vivo. The discrepancy of GH-IGF pathway between inoculation tumor and small intestine of the host may help to explain the phenomena that GH doesn't accelerate growth of pancreatic tumor in vivo. Key words: Somatomedins;  Pancreatic neoplasms;  Growth hormone;  Receptor,IGF