Efeito dos análogos da insulina glargina e NPH sobre o crescimento de tumor pancreático humano em modelo murino de diabetes melito

Abstract

Diabetes Mellitus (DM) and cancer are among the most common diseases of the human population worldwide. Administration of long-acting insulin analogues has been used in the treatment of hyperglycemia present in DM and the hypoglycemic effects occur from binding to insulin/insulin-like growth factor (IGF) receptors and intracellular responses related to cellular metabolism. Some studies suggest that long-acting insulin, such as Glargine, may increase the risk of cancer. However, currently, studies are inconclusive in demonstrating intracellular mechanisms of pancreatic cancer in response to this analogue. The aim of this study was to analyze the effect of Glargine on the human pancreatic cancer cells growth in nude diabetic mice. In addition, to evaluate cell proliferation, the expression of VEGF and PI3K/AKT, mTOR and cyclin D1 pathways. Thus, the human pancreatic ductal adenocarcinoma cell line BxPC-3 was inoculated subcutaneously in streptozotocin-induced balb/c female diabetic mice. After DM induction and inoculation of the cells, the animals were treated with GLAR (GLAR group) or neutral insulin protamine Hagedorn (NPH group), both at 1U/day for 28 days. Results: At the end of the protocol, we verified that there was no difference in weight gain between groups (weight at the last day 21.1 ± 1.9g in NPH and 21.8 ± 1.4g in GLAR, p=0.99). The animals in both groups presented a similar glycemic control, which did not alter the survival of the animals between groups. Regarding tumor growth, there was no difference between groups (1.23 ± 1.70 mm3/day/g in NPH vs 0.68 ± 0.86 mm3/day/g in GLAR, p=0.92), and it is confirmed through the proliferation analysis by PCNA and cyclin D1, with no difference in cyclin D1 expression between groups (relative expression of 1.03 ± 0.08 in NPH and 1.21 ± 0.19 in GLAR, p=0.40). There was no difference in VEGF-A expression and there was no significant correlation with tumor size (NPH: R=-0.035, p=0.96; GLAR: R=0.285, p=0.55). In addition, the treatments induced similarly the expression of the type A insulin receptor (relative expression of 2.18 ± 2.47 in NPH and 1.26 ± 1.20 in GLAR, p=0.79) and type B (relative expression of 1.02 ± 0.21 in NPH and 1.40 ± 0.51 in GLAR, p=0.08) and IGF-I receptor (relative expression of 1.02 ± 0.23 in NPH and 0.98 ± 0.21 in GLAR, p=0.67), as well as equally induced the pathways related to metabolism and cell growth, evaluated by Western Blot for AKT and mTOR pathways. We conclude that, in this studied model, there was no difference between Glargina and NPH insulins regarding tumor growth, cell proliferation, expression of insulin and IGF-I receptors as well as activation of AKT and mTOR signaling pathways.