4-Me-6E,8E-hexadecadienoic acid isolated from a marine-derived strain of Clonostachys rosea reduces viability of MCF-7 breast cancer cells and gene expression of lipogenic enzymes

Abstract

Conjugated fatty acids (CFA) have attracted particular attention because of their remarkable biological activities such as anti-carcinogenic, anti-obesity, antithrombotic and anti-atherogenic [1]. The main natural sources of CFA correspond to ruminant milk, algae and seed oils of several plants [2], but fungi have been widely recognized for their production of essential FA such as arachidonic or docosahexaenoic acids which have a major interest in human health and nutrition. Our attention was focused on a marine-derived strain of Clonostachys rosea isolated from marine sediments of the Loire estuary (France), which produced high amounts of triglycerides and an original branched CFA, first identified as 4-Me-6,8-hexadecadienoic acid (4-Me-6,8 – 16:2). In order to optimize the production of this CFA to undergo pharmacological studies, an OSMAC approach has been performed on 7 culture media. Cultures on DCA medium showed the highest production with 19% of total FA. After fungal biomass extraction and saponification of the lipid crude extract, 4-Me-6,8 – 16:2 was purified using urea inclusion and liquid chromatography on AgNO3-impregnated silica gel. The CFA structure was deduced from 1H-NMR and IR analyses confirming the trans configuration of double bonds. When tested against MCF-7 breast cancer cell line, 4-Me-6E,8E-16:2 reduced the viability in a dose dependent manner (up to 75% inhibition after 48h at 100µM). Numerous studies have demonstrated that cell proliferation is associated with hyperactivity of lipogenesis [3, 4]. We have then assessed the effect of 4-Me-6E,8E-16:2 on gene expression of two lipogenic enzymes, the ACC (Acetyl coA Carboxylase) and the FAS (Fatty Acid Synthase). At 50µM and after 24h, expression of ACC and FAS were reduced of 50% and 35%, respectively. These results are promising and need to be completed in order to determine the mechanisms by which 4-Me-6E,8E-16:2 reduce cancer cell proliferation and inhibits the expression of lipogenic enzymes.