[KLF3 regulates the movement, migration and invasion of breast cancer cells through STAT3]

Objective: To observe the effect of KLF3 on the expression of STAT3 in breast cancer cells, and to explore the potential mechanism of KLF3 affecting the movement, migration and invasion of breast cancer cells. Methods: Firstly, the expression of STAT3 was detected by Western blot, real-time fluorescent quantitative PCR, luciferase reporter system and chromatin immunoprecipitation in breast cancer cells. Secondly, the STAT3 promoter mutant was constructed. The plasmid further confirmed the effect of KLF3 on the activity of STAT3 promoter; the cell scratching test and Transwell method were used to detect the ability of cell movement, migration and invasion. Finally, animal experiments were conducted to verify the effect of knockdown of KLF3 on tumor metastasis in animals. Results: In breast cancer cells, knockdown of KLF3 promoted STAT3 protein expression. The mRNA level of STAT3 was increased by (3.58±0.65) fold after knockdown of KLF3 in MDA-MB-231 cells, while the mRNA level of STAT3 was increased by (2.28±0.19) fold after KLF3 knockdown in MCF-7 cells (P<0.001). KLF3 boundto the promoter region of STAT3. The transcriptional activity of STAT3 increased by (2.47±0.87) fold after knockdown of KLF3 in MDA-MB-231 cells, while the transcriptional activity of STAT3 increased by (2.63±0.65) fold after KLF3 knockdown in MCF-7 cells, P<0.01. KLF3 knockdown inhibitedthe movement,migrate and invade of breast cancer cells. Based on this, silence STAT3 partially reversed the function of KLF3. Knockdown of KLF3 promotedtumor metastasis in mice. Conclusions: KLF3 knockdown can promote the transcriptional activity of STAT3, which promotes the protein expression of the latter. KLF3 can affect the movement, migration and invasion of breast cancer cells through STAT3. KLF3 may be a potential target for the treatment of metastatic breast cancer.