| Conjugated linoleic acid(CLA) is a kind of functional oils and fats, a natural composition in food, non-toxic side effects to human body, which mainly exists in cream and meat of rumen animals(cattle, sheep, etc.). In recent years, a large number of animal experiments have showed that CLA has anti-cancer, anti-atherosclerosis,reducing the fat deposition and other important physiological functions. Vaccenic acid(VA, t11-C18:1) is a kind of natural trans fatty acid, yet the relationship between trans fatty acids and cancer is unclear, which needs to be studied further. In this paper,we applied human breast cancer cell MCF-7 for in vitro model to select more effective anti-cancer CLA isomer and discuss the effect of EA and VA on MCF-7 cell,by using MTT assay, fluorescence staining and flow cytometry to compare the influence of three kinds of CLA isomers(c9,t11-CLA, t10,c12-CLA, t9,t11-CLA) and two kinds of trans fatty acids(EA,VA) on breast cancer cell MCF-7 in cell growth,apoptosis and cell cycle. In addition, we used RT-PCR and Western blot method to study the ability that three kinds of CLA isomers activate PPARγ and the relationship that PPARγ regulate apoptosis-associated genes and proteins expression, from the levels of gene and protein to clarify potential mechanisms that CLA isomers and VA induce human breast cancer cell MCF-7 apoptosis, to apply the natural products as early as possible and provide a experimental theory for the prevention and treatment of breast cancer. The experimental results were showed as follows:Three kinds of CLA isomers and trans fatty acids VA treated MCF-7 cell after 48 h,all could inhibit MCF-7 cell proliferation and promote apoptosis dose-dependently,but the inhibitory effect of CLA significantly stronger than the VA. When the concen-tration was 50 μmol/L or less, the inhibitory effect of t10,c12-CLA to MCF-7 cell was better than c9,t11-CLA, when 100 μmol/L or higher, the inhibitory effect of c9,t11-CLA to MCF-7 cell was better than t10,c12-CLA. when the concentration of t9,t11-CLA was 50 μmol/L, proliferation inhibiting rate of MCF-7 cell reached34.01%, it was the most efficient isomer by decreasing MCF-7 proliferation. EA treated MCF-7 cell 48 h, showing that it promoted MCF-7 cell proliferation in a certain dose range. Compared with control group, with the increase of CLA isomersand VA groups action concentration, G0/G1 phase shorten and S phase prolonged in MCF-7 cells, obviously, CLA and VA could block cells at S phase, blocked DNA synthesis, the following cell cycle activity could not continue, so that inhibited cell proliferation. Hence we speculated that CLA and VA might inhibit cell proliferation and induce apoptosis through affect cell cycle progression.Different CLA isomers could promote MCF-7 cell PPARγ gene and protein expression, and the change tendency of PPARγ and promotive apoptotic genes bcl-xS was consistent. Trans fatty acid VA could also promote expression of promotive apoptotic genes bcl-xS mRNA and protein Bax. 100 μmol/L c9,t11-CLA group, 50μmol/L t10,c12-CLA group, 50 and 100 μmol/L t9,t11-CLA groups, anti-apoptotic gene bcl-xL mRNA and its protein expression decreased, especially, t9,t11-CLA group, the expression level of anti-apoptotic gene bcl-xL mRNA and its protein decreased obviously. From the expression ratios of bcl-xS/bcl-xL mRNA and proteins Bax/Bcl-2, the best working concentration was 100 μmol/L of VA and c9,t11-CLA,50 μmol/L of t10,c12-CLA and t9,t11-CLA. Results indicated that VA and three kinds of CLA isomers could all induce expression change of apoptosis related genes the bcl-xS, bcl-xL and proteins Bax, Bcl-2, but the optimal concentration was different.By promoting the expression of PPARγ, CLA isomers regulate the expression of apoptosis related genes and proteins, further inducing cell apoptosis. |
PDF Full Text Request