By Brooke Martin

Faculty Mentor: Dr. Laura Sipe

Abstract

The Effect of Methionine Restriction on the Autophagy of Breast Cancer Cells

Methionine is an essential amino acid involved in numerous cellular processes, including DNA, RNA, and histone methylation via its metabolite, S-adenosylmethionine (SAM). DNA methylation can inhibit autophagy related genes and reduce transcription and translation. This leads to a decrease in protein synthesis. Autophagy, a cellular recycling mechanism triggered by nutrient deprivation, plays a complex role in cancer biology—helping cells survive stress but potentially leading to cell death when overactivated. This study explores the impact of methionine restriction on autophagy in E0771 mouse breast cancer cells, a spontaneous tumor model. Cells were cultured in 12-well plates (N=5, with two technical replicates per treatment) under four methionine concentrations: 100% (control), 12%, 6%, and 3%. RNA was extracted using Trizol, quantified, and normalized to <500 ng before synthesizing cDNA. Gene expression of autophagy-related markers ATG-5 and TFEB was analyzed using qPCR, with β-actin as the reference gene. Results showed that methionine restriction upregulated autophagy markers, but there was no significant difference in ATG-5 or TFEB expression among the restricted groups (12%, 6%, and 3%), indicating the effect is not dose-dependent. These findings suggest that methionine restriction triggers autophagy, regardless of concentration level. Future research should investigate whether increased autophagy leads to accelerated cell death, and whether methionine restriction could sensitize cancer cells for immune recognition. Understanding these dynamics may reveal potential therapeutic strategies for targeting breast cancer metabolism.