(PTFS15-06-26) Agricultural Waste to Functional Resource: Strawberry Leaf Extract Suppresses Cancer Cell Growth via Regulation of Fatty Acid Desaturation

Objectives: Cancer remains the leading cause of death in Japan, highlighting the importance of effective strategies for primary prevention. Food-derived bioactive compounds have attracted considerable attention as modulators of cellular metabolism involved in carcinogenesis. Strawberry (Fragaria × ananassa Duch.) leaves contain higher levels of polyphenols than the edible fruit but are generally discarded as agricultural waste. We investigated whether strawberry leaf extract (SLE) suppresses cancer cell proliferation and explored its underlying metabolic mechanisms.

Methods: SLE was prepared by extraction of strawberry leaves with 50% ethanol. Ehrlich ascites tumor cells (EATC) were cultured with SLE. Cell number, cell viability, DNA synthesis, and intracellular triglyceride (TG) accumulation were evaluated. To clarify the mechanism, fatty acids were co-administered and gene and protein expression related to lipid metabolism were analyzed.

Results: SLE significantly inhibited EATC proliferation in a concentration-dependent manner and induced cell cycle arrest at the G1/S transition. SLE also markedly reduced intracellular TG accumulation. Mechanistic experiments revealed that the SLE-induced reduction in cell number was not restored by palmitic acid (PA) but was reversed by oleic acid (OA), suggesting that SLE suppresses cancer cell growth through modulation of fatty acid desaturation. Further analyses indicated that stearoyl-CoA desaturase-1 (SCD1), a key enzyme controlling the conversion of saturated fatty acids to monounsaturated fatty acids, is likely involved in this process.

Conclusions: These findings demonstrate that strawberry leaf extract inhibits cancer cell proliferation, potentially through disruption of lipid metabolic pathways involving fatty acid desaturation. Our results highlight the potential of strawberry leaves - currently discarded agricultural by-products - as a novel source of bioactive compounds for dietary strategies targeting cancer prevention.

Funding Sources: This research was conducted with the support of faculty research fund from Osaka Metropolitan University.

Express Co., Ltd. provided a part of the grant.