3-Bromopyruvate inhibits pancreatic tumor growth by stalling glycolysis, and dismantling mitochondria in a syngeneic mouse model

Abstract

Pancreatic cancer (PC) is the fourth-most-deadly cancer in the United States with a 5-year survival rate of only 8%. The majority of patients with locally advanced pancreatic cancer undergo chemotherapy and/or radiation therapy (RT). However, current treatments are inadequate and novel strategies are desperately required. 3-Bromopyruvate (3-BP) is a promising anticancer drug against pancreatic cancer. It exerts potent anticancer effects by inhibiting hexokinase II enzyme (HK2) of the glycolytic pathway in cancer cells while not affecting the normal cells. 3-BP killed 95% of Panc-2 cells at 15 μM concentration and severely inhibited ATP production by disrupting the interaction between HK2 and mitochondrial Voltage Dependent Anion Channel-1 (VDAC1) protein. Electron microscopy data revealed that 3-BP severely damaged mitochondrial membrane in cancer cells. We further examined therapeutic effect of 3-BP in syngeneic mouse pancreatic cancer model by treating animals with 10, 15 and 20 mg/kg dose. 3-BP at 15 & 20 mg/kg dose level significantly reduced tumor growth by approximately 75-80% in C57BL/6 female mice. Immunohistochemistry data showed complete inhibition of hexokinase II (HK2) and TGFβ, in animals treated with 3-BP drug. We also observed enhanced expression of active caspase-3 in tumor tissues exhibited apoptotic death. Flow Cytometry analysis showed significant inhibition in MDSC (CD11b) population in treated tumor which may have allowed infiltration of CD8+ T cells and inhibited tumor growth. Notably, metabolomic data also revealed severe inhibition in glycolysis, NADP, ATP and lactic acid production in cancer cells treated with 40 μM 3-BP. Importantly, we also observed inhibition in lactic acid production responsible for tumor aggression. These results provide new evidence that 3-BP severely inhibit glucose metabolism in cancer cells by blocking hexokinase II, and disrupting mitochondria by suppressing BCL2L1 in pancreatic cancer.