Objective To explore the effects of cAMP-response element binding protein 1(CREB1) gene silencing on the proliferation, apoptosis, migration, and invasion of breast cancer MCF-7 and MDA-MB-231 cell lines.

Methods Two short hairpin RNAs (shRNAs) were designed and constructed for CREB1 gene sequence, and then transfected into human breast cancer MCF-7 and MDA-MB-231 cell lines to silence CREB1 expression.The experimental groups included shCREB1#1 and shCREB1#2 groups, and the shSCR empty plasmid was transfected into the above cell lines as the negative control group.The transfection efficiency was determined by real-time quantitative PCR and Western blotting methods.CCK-8 assay was used to detect cell proliferation.Colony formation experiment was used to detect the colony formation ability of breast cancer cells.Flow cytometry was used to detect the cell cycle and apoptosis rate.Cell wound assay and transwell assay were used to detect cell migration and invasion, respectively.The expression of cell cycle and apoptosis-related proteins were detected by Western blotting.

Results In MCF-7 and MDA-MB-231 cell lines, compared with the negative control group, the relative CREB1 mRNA and protein expression levels were decreased in shCREB1#1 and shCREB1#2 groups (P < 0.001).After CREB1 silencing, the proliferation, colony formation, migration, and invasion abilities of MCF-7 and MDA-MB-231 cell lines were decreased.Meanwhile, the cell apoptosis rate was increased (P < 0.05).CREB1 silencing could down-regulate the expression levels of cell cycle-related proteins (CDK2, CDK4, CDK6, and Cyclin D₁) and anti-apoptotic proteins (Bcl-2 and Survivin) and up-regulate the expression of pro-apoptotic proteins (Caspase 3 and Bax, P < 0.05).

Conclusions CREB1 silencing could inhibit the proliferation, migration, and invasion of breast cancer cells and induce cell apoptosis.