Enhanced expression of the insulin receptor substrate-2 docking protein in human pancreatic cancer - PubMed (original) (raw)

. 1998 Oct 1;58(19):4250-4.

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Enhanced expression of the insulin receptor substrate-2 docking protein in human pancreatic cancer

M Kornmann et al. Cancer Res. 1998.

Abstract

Insulin receptor substrate-2 (IRS-2) is a multisite docking protein implicated in mitogenic signaling after activation of the insulin and insulin-like growth factor (IGF)-I receptors. In the present study, we characterized IRS-2 expression and function in human pancreatic cancer. IRS-2 mRNA and protein were expressed in ASPC-1 and COLO-357 human pancreatic cancer cell lines. Insulin, IGF-I, and IGF-II enhanced the growth of both cell lines, stimulated tyrosine phosphorylation of IRS-2, and increased IRS-2-associated phosphatidylinositol (PI) 3-kinase activity. The mitogenic effects of insulin, IGF-I, and IGF-II were markedly attenuated by the PI 3-kinase inhibitor LY 294002. Northern blot analysis of total RNA extracted from normal and cancerous tissues revealed that IRS-2 mRNA levels were increased in the cancer tissues (P = 0.032). In the normal pancreas, IRS-2 immunoreactivity was present at low levels in some ductal and acinar cells and at moderate levels in a heterogeneous pattern in all of the endocrine islets. In the pancreatic cancers, IRS-2 was abundant in the ductal-like cancer cells. These findings indicate that IRS-2 is overexpressed in human pancreatic cancer and suggest that it may contribute to enhanced mitogenic signaling via the PI 3-kinase pathway, thereby leading to excessive growth stimulation in this malignancy.

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