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Abstract: Cisplatin is the most widely used chemotherapeutic agent, and resistance of neoplastic cells against this cytoxicant poses a major problem in clinical oncology. Here, we explored potential metabolic vulnerabilities of cisplatin‐resistant non‐small human cell lung cancer and ovarian cancer cell lines. Cisplatin‐resistant clones were more sensitive to killing by nutrient deprivation in vitro and in vivo than their parental cisplatin‐sensitive controls. The susceptibility of cisplatin‐resistant cells to starvation could be explained by a particularly strong dependence on glutamine. Glutamine depletion was sufficient to restore cisplatin responses of initially cisplatin‐resistant clones, and glutamine supplementation rescued cisplatin‐resistant clones from starvation‐induced death. Mass spectrometric metabolomics and specific interventions on glutamine metabolism revealed that, in cisplatin‐resistant cells, glutamine is mostly required for nucleotide biosynthesis rather than for anaplerotic, bioenergetic or redox reactions. As a result, cisplatin‐resistant cancers became exquisitely sensitive to treatment with antimetabolites that target nucleoside metabolism. [ABSTRACT FROM AUTHOR]

Summary Caloric restriction mimetics (CRMs) mimic the biochemical effects of nutrient deprivation by reducing lysine acetylation of cellular proteins, thus triggering autophagy. Treatment with the CRM hydroxycitrate, an inhibitor of ATP citrate lyase, induced the depletion of regulatory T cells (which dampen anticancer immunity) from autophagy-competent, but not autophagy-deficient, mutant KRAS-induced lung cancers in mice, thereby improving anticancer immunosurveillance and reducing tumor mass. Short-term fasting or treatment with several chemically unrelated autophagy-inducing CRMs, including hydroxycitrate and spermidine, improved the inhibition of tumor growth by chemotherapy in vivo. This effect was only observed for autophagy-competent tumors, depended on the presence of T lymphocytes, and was accompanied by the depletion of regulatory T cells from the tumor bed. [ABSTRACT FROM AUTHOR]