MiR-145, miR-133a and miR-133b inhibit proliferation, migration, invasion and cell cycle progression via targeting transcription factor Sp1 in gastric cancer.

MicroRNAs have recently emerged as key regulators of gastric cancers. Here we found that miR-145, miR-133a and miR-133b were down-regulated in gastric cancer tissues and cell lines. Overexpression of miR-145, miR-133a and miR-133b induced G1 cell cycle arrest and inhibited cell proliferation, migration and invasion in vitro. MiR-145, miR-133a and miR-133b targeted the transcription factor SP1, knockdown of which reduced the expression of MMP-9 and Cyclin D1 that were involved in cell growth and invasion. Thus, our findings demonstrated for the first time that miR-145, miR-133a and miR-133b suppressed the proliferation, migration, invasion and cell cycle progression of gastric cancer cells through decreasing expression of Sp1 and its downstream proteins.