ObjectiveTo observe the effects of free fatty aids (FFAs) on the apoptosis and migration of human breast cancer cells ( MDA-MB-231 ).MethodsBreast cancer cells were exposed to oleic acid (OA) and palmitic acid (PA) with different concentrations (50,200,and 500 umol/L).Quantity RT-PCR was conducted to detect mRNA expression of PTEN,and Western blot to detect protein expression of PTEN and Bcl-2.Cell apoptosis was measured with TUNEL method,and migration measured with transwell method.ResultsThe mRNA and protein expressions of PTEN in MDA-MB-231 cells were down-regulated after OA stimulation,but up-regulated after PA stimulation ( all P ＜ 0.05 ).The protein expression of Bcl-2 increased after OA stimulation and decreased after PA stimulation ( both P ＜ 0.05 ).PA increased the apoptosis,and both OA and PA enhanced the invasion of MDA-MB-231 cells.ConclusionsPA may promote apoptosis of MDA-MB-231 cells through changing the expression of the tumor suppressor PTEN,but also increases the invasion of the cancer cells.The invasion of cancer cells could be enhanced by OA stimulation as well.