Preliminary study on the effects of pancreatic cancer-derived microvesicles on glycometabolism

Abstract

Objective To explore the role of pancreatic cancer-derived microvesicles (MV) and their enclosed microRNAs (miRNA) in the pathogenesis of pancreatic cancer induced diabetes mellitus (DM). Methods The supernatants of three pancreatic cancer cell lines SW1990, BxPC3 and PANC1 were collected, and MV were isolated with gradient centrifugation.The entrance of MV into pancreatic islet cell line MIN6 was proved by Western blot assay and fluorescence-label method. The miRNA-19a levels were measured in MV and MV-free supernatants of three pancreatic cancer cells lines. The three experimental groups were MIN6 cells separately treated by MV derive from SW1990, BxPC3 and PANC1, and untreated MIN6 cells were assigned to the control group. The miRNA-19a levels as well as changes of glucose stimulated insulin secretion (GSIS) were measured. Afterward, pre-miRNA-19a and anti-miRNA-19a were transfected into MIN6 cells by liposome, and the effects of them on GSIS were observed. Results CD63 and AGO2 as the protein markers of MV and the entrance of MV from pancreatic cancer into pancreatic islet cell line MIN6 were detected by Western blotting.The miRNA-19a levels in MV and MV-free supernatants of SW1990, BxPC3 and PANC1 were (132.7±16.0), (32.8±4.3), (78.4±8.9), (22.6±3.3), (63.3±12.0) and (23.3±3.3) pmol/L, respectively, and the differences were statistically significant (t=10.44, 10.12 and 5.56, all P<0.01). Compared to the MIN6 control group, the miRNA-19a levels of MIN6 treated by MV from SW1990, BxPC3 and PANC1 significantly increased, and the 2-△△Ctvalue was 2.02±0.50, 1.80±0.41 and 2.11±0.59, respectively, and the differences were statistically significant (t=2.97, 2.77, 2.84; all P<0.05). Stimulated with high glucose, the GSIS of pancreatic islet cells treated by SW1990, BxPC3 and PANC1 in three groups decreased, which were (103.73±16.49), (141.17±11.26), and (138.24±13.97) ng·mg protein-1·h-1 MV, respectively, and that of control group was (256.24±33.05) ng·mg protein-1·h-1. The differences were statistically significant (t=4.13, 3.30 and 3.29, all P<0.05). Compared with control group, GSIS of pre-miRNA-19a treated MIN6 remarkably decreased, which was (126.17±62.87) ng·mg protein-1·h-1 and (316.72±91.87) ng·mg protein-1·h-1, and the difference was statistically significant (t=2.97, P<0.05). GSIS of MIN6 cells transfected with anti-miRNA-19a was higher than that of control group, which was (697.47±77.62) ng·mg protein-1·h-1and (355.33±84.77) ng·mg protein-1·h-1, and the difference was statistically significant (t=-2.97, P<0.05). Conclusion The entrance of MV derived from pancreatic cancer into pancreatic islet cell line MIN6 may cause the dysfunction of insulin secretion an important signaling molecules, miRNA-19a. Key words: Pancreatic neoplasms; Diabetes mellitus; MicroRNAs; Microvesicle