Effects of human breast stromal cells on conjugated linoleic acid (CLA) modulated vascular endothelial growth factor-A (VEGF-A) expression in MCF-7 cells

Background: Conjugated linoleic acid (CLA), a naturally occurring compound found in ruminant dairy and beef products, has been shown to possess anti-cancer ability in vivo and in vitro. There are several CLA isomers in ruminant produced food products, among which t10c12-CLA and c9,t11-CLA are most potent. Vascular endothelial growth factor-A (VEGF-A) has been implicated as an angiogenesis-activating cytokine. Our previous results indicated that CLA induced suppression of VEGF-A in MCF-7 cells, which may be one of CLA's anticancer mechanisms. Materials and Methods: The effects of t10c12-CLA and c9,t11-CLA on VEGF-A mRNA and protein expression in MCF-7 cells, which were co-cultured with human breast stromal cells isolated from breast tissues of surgical specimens of mammoplasty and breast cancer patients, were detected by RT-PCR and Western blot analysis. Results: VEGF-A mRNA and protein expressions were significantly (p<0.05) elevated in co-cultured MCF-7 cells in comparison with cultured MCF- 7 cells alone. Normal human breast stromal cells contribute greater effects in increasing VEGF-A protein expression in MCF- 7 cells. Both t10,c 12-CLA and c9, t11-CLA significantly (p<0.05) decreased VEGF-A mRNA and protein levels in co-cultured MCF- 7 cells. t10c12-CLA appeared to be the more active isomer than c9, tl11-CLA. Conclusion: The results indicate that dietary CLA might serve as a chemo-therapeutic agent in human breast cancers by down-regulating VEGF-A expression.