Cucurbitacin B from Cucurbitaceae Plants: Treating Pancreatic Cancer via Inducing Mitophagy, Inhibiting Glycolysis, and Enhancing Immune Function

Background: Cucurbitacin B (CuB) is a relatively unique and valuable component in plants of the Cucurbitaceae family due to its diverse and remarkable physiological activities, but its specific mechanisms in regulating tumor metabolism and immune response remain unclear. The hypoxic tumor microenvironment (TME) of pancreatic cancer induces metabolic reprogramming in cancer cells, causing them to rely on glycolysis for energy. LDHA, a key enzyme in glycolysis, can suppress glycolysis and tumor growth when inhibited. Objective: The objective of this study was to investigate the mechanism of CuB against pancreatic cancer and its effect on the immune system. Methods: In this study, cell migration/invasion assays, immunofluorescence, ELISA, Western blot, CETSA, flow cytometry, mouse models, and metabolomic and transcriptomic analyses were utilized to systematically elucidate the mechanism by which CuB inhibits pancreatic cancer and activates the immune system. Results: This study confirms that CuB inhibits pancreatic cancer by suppressing the PI3K/Akt/mTOR pathway and activating PINK1/Parkin to induce mitophagy, thereby inhibiting cell migration, invasion, and proliferation. It downregulates the expression of LDHA to block glycolysis, reduce lactate production and efflux, and improve the acidic TME. CuB also induces ICD to activate dendritic cells, promote CD8+ T-cell and M1 macrophage infiltration, and reduce the levels of regulatory T cells. Metabolomic and transcriptomic analyses validate CuB’s dual effects on metabolic reprogramming and immune activation. Conclusions: This study, for the first time, reveals that CuB induces mitophagy via the PI3K/Akt/mTOR and PINK1/Parkin pathways to selectively eliminate damaged mitochondria and suppress tumor energy metabolism. CuB inhibits pancreatic cancer through a triple mechanism—inducing mitophagy, inhibiting glycolysis, and activating immunity—which provides innovative insights for pancreatic cancer therapy.