MicroRNA-300 promotes apoptosis and inhibits proliferation, migration, invasion and epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway by targeting CUL4B in pancreatic cancer cells.

The study aims to verify the hypothesis that up-regulation of microRNA-300 (miR-300) targeting CUL4B promotes apoptosis and suppresses proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of pancreatic cancer cells by regulating the Wnt/β-catenin signaling pathway. Pancreatic cancer tissues and adjacent tissues were collected from 110 pancreatic cancer patients. Expression of miR-300, CUL4B, Wnt, β-catenin, E-cadherin, N-cadherin, Snail, GSK-3β, and CyclinD1 were detected using qRT-PCR and Western blot. CFPAC-1, Capan-1, and PANC-1 were classified into blank, negative control (NC), miR-300 mimics, miR-300 inhibitors, siRNA-CUL4B, and miR-300 inhibitors + siRNA-CUL4B groups. The proliferation, migration, invasion abilities, the cell cycle distribution, and apoptosis rates were measured in CCK-8 and Transwell assays. Pancreatic cancer tissues showed increased CUL4B expression but decreased miR-300 expression. When miR-300 was lowly expressed, CUL4B was upregulated which in-turn activated the Wnt/β-catenin pathway to protect the β-catenin expression and thus induce EMT. When miR-300 was highly expressed, CUL4B was downregulated which in-turn inhibited the Wnt/β-catenin pathway to prevent EMT. Weakened cell migration and invasion abilities and enhanced apoptosis were observed in the CUL4B group. The miR-300 inhibitors group exhibited an evident increase in growth rate accompanied the largest tumor volume. Smaller tumor volume and slower growth rate were observed in the miR-300 mimics and siRNA-CUL4B group. Our study concludes that lowly expressed miR-300 may contribute to highly expressed CUL4B activating the Wnt/β-catenin signaling pathway and further stimulating EMT, thus promoting proliferation and migration but suppressing apoptosis of pancreatic cancer cells.