Insulin mediates hypoxia-inducible factor-1α in human pancreatic cancer ASPC-1 cells

Abstract

Objective To investigate the effect of insulin on the expression of hypoxia-inducible factor-1α in human pancreatic cancer cell line ASPC-1. Methods We divided ASPC-1 cells into five groups: normoxia; normoxia stimulated with insulin; hypoxia; hypoxia pretreated with different concentration of insulin; hypoxia of different time points pretreated with same concentration of insulin. Real-time PCR was used to test the expression of HIF-1α mRNA. Immunohistochemistry was used to examine the expression of HIF-1α in ASPC-1 of insulin treated cancer cells. Western blot was used to determine the expression of HIF-1 α protein in those cells. Transwell was used to test whether insulin could enhance the invasion ability of ASPC-1 pancreatic cancer cells. Results Insulin promotes HIF-1α protein expression. ASPC-1 cells expressed low levels of HIF-1α protein under normoxic condition. After stimulated with insulin, the expression of HIF-1 α protein significantly increased (P ＜ 0. 05 ). After treated with hypoxia, the expression of HIF-1α protein also increased(P ＜ 0. 05 ). Low concentrations of insulin didn't increase the expression of HIF-1α under hypoxic environment ( P ＞ 0. 05 ), while high concentration of insulin could increase its expression(P ＜ 0. 05). When ASPC-1 cells pretreated with insulin suffered from hypoxia, the expression of HIF-1α first increased then decreased moderately( P ＜0. 05). Insulin could enhance the invasion ability of pancreatic cancer cells( P ＜ 0. 05 ). Conclusions Insulin mediates the expression of HIF-1α protein in human pancreatic cancer ASPC-1 cells with the characteristics of dose and time dependency. Insulin could enhance the invasion ability of ASPC-1 cells. Key words: Pancreatic neoplasms; Insulin; Anoxia; Hypoxia-inducible factor 1