Caloric Restriction Mimetics Enhance Anticancer Immunosurveillance.
Level 5 - mechanism / opinion, no new human data
Preclinical animal (mouse) research without human subjects
PubMed 27411589 · doi:10.1016/j.ccell.2016.05.016
What was done
Evaluated the effects of short-term fasting and caloric restriction mimetics (CRMs)—specifically the ATP citrate lyase inhibitor hydroxycitrate and spermidine—in mice bearing mutant KRAS-induced lung cancers and other tumors. Researchers assessed tumor mass, chemotherapy-induced tumor growth inhibition, regulatory T-cell levels in the tumor bed, and the necessity of tumor autophagy competency and T lymphocytes.
What was found
The abstract provides directional findings without quantitative data or effect sizes. Hydroxycitrate depleted regulatory T cells from autophagy-competent, but not autophagy-deficient, mutant KRAS-driven lung tumors in mice, reducing tumor mass and improving immunosurveillance. Short-term fasting and chemically unrelated CRMs (hydroxycitrate, spermidine) enhanced chemotherapy-induced tumor growth inhibition in vivo. This effect required both host T lymphocytes and tumor autophagy competency, and was accompanied by tumor-bed regulatory T-cell depletion.
Why it matters
Identifies a potential immunological mechanism linking nutrient deprivation, caloric restriction mimetics, and tumor autophagy to enhanced chemotherapy efficacy via regulatory T-cell reduction.
Limits
The findings are derived entirely from preclinical mouse models; translational efficacy, optimal dosing, and safety in humans are unestablished. The abstract reports no quantitative values, sample sizes, or statistical confidence intervals.
Cited by
- supports ATP citrate lyase is the primary enzyme generating the cytosolic acetyl-CoA pool, and hydroxycitrate inhibits it, causing acetyl-CoA depletion, deacetylation, and autophagy.
- supports Combining caloric restriction mimetics like spermidine, hydroxycitrate, or resveratrol with chemotherapy enhances the anti-cancer immune response, and this benefit is lost if malignant cell autophagy is inhibited, extracellular ATP is destroyed, or T cells are removed.
- supports Guido Kroemer demonstrated that autophagy induced during starvation or by caloric restriction mimetics is essential for exposing cancer cells to the immune system.