An Investigation into Autophagy in Methionine-Restricted Cancer Cells

Date of Award


Document Type




First Reader

Dr. Sharon Hamilton

Second Reader

Dr. Isabelle R. Miousse

Third Reader

Dr. Marvin Pate


Previous data from our lab indicate that dietary methionine restriction leads to a reduction in cancer growth. Interestingly, evidence also indicates that methionine restriction can lead to an increase in cellular lifespan. Although the exact mechanism that causes this paradox is poorly understood, some research indicates that methionine restriction causes an increase in autophagy. Autophagy is a mechanism that cells utilize to recycle damaged organelles. It is also believed that methionine signals through mTOR, a protein kinase, to promote cellular growth and inhibit autophagy. We hypothesize that disabling autophagy will increase the positive effects of methionine restriction. In this project, we are using a wild-type murine melanoma cell line with autophagy- deficient knockouts of the gene Atg5. Normal fibroblast cell lines were used as a control. The cell lines were cultured in either control (200mM methionine) or methionine restricted (5mM methionine) media. We investigated the mTOR and autophagy pathways with protein expression using Western blots; gene expression was investigated with quantitative real-time PCR. We found that mTOR and autophagy do not seem to affect one another. We also found that autophagy-deficient cells are not affected by MR any more than wild-type cells. By further investigating the mechanisms that cancer cells use to grow, therapies can be developed that exploit these mechanisms.

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