Mechanism of miRNA-26a on the Proliferation of Pancreatic Tumor Cells by Regulating the Expression of Cycline2

qRT-PCR was used to measure the expression of miRNA-26a in pancreatic epithelial cells (HPDE) and human pancreatic cancer cell lines PANC-1 and MIA PaCa-2.

PANC-1 and MIA PaCa-2 cell lines were infected with lentiviruses to construct PANC-miR-26a and MIA-miR-26a, and RT-PCR was used to detect the infection efficiency. The cell proliferation ability of PANC-miR-26a and MIA-miR-26a were examined by CCK-8 assay, and apoptosis was detected by flow cytometry. Western blotting was used to detect the expressions of CyclinE2 protein and mitochondria-associated apoptotic proteins.

miR-26a was expressed in human normal pancreatic epithelial cells (HPDE), and not detected in PANC-1 and MIA PaCa-2; miR-26a was highly expressed in the cell lines PANC-miR-26a and MIA-miR-26a infected by the virus particles. The absorbance values of PANC-miR-26a and MIA-miR-26a were lower than those of NC1 and PANC-1 in control group. The apoptosis rates of PANC-miR-26a and MIA-miR-26a were substantially higher than those of the control group. The overexpression of miR-26a inhibited the expression of the target protein CyclinE2 in PANC-miR-26a and MIA-miR-26a. The expression of the anti-apoptotic protein Bcl-2 was decreased in PANC-miR-26a and MIA-miR-26a, while the expression of the pro-apoptotic protein Bax was increased. Compared with HPDE, miR-26a was down-regulated in PANC-1 and MIA PaCa-2. After overexpression of miR-26a, the proliferation of PANC-1 and MIA PaCa-2 cell lines was weakened.

Molecular mechanism is the negative regulation of CyclinE2 by miR-26a as well as the expressions of downstream mitochondrial apoptosis proteins Bcl-2 and Bax.