6-[(1,4-Naphthoquinone-2-yl)methyl]thio-Glucose Conjugates, a Novel Targeted Approach for Advanced Prostate Cancer

The Warburg effect is a shift from oxidative phosphorylation to anaerobic glycolysis, accompanied by an enormous increase in glucose uptake into cancer cells. We have utilized this effect to design a new group of targeted 1,4-naphthoquinone-glucose derivatives conjugated with a novel thiomethylene linker that are cytotoxic to prostate cancer cells. Compound PeS-9 revealed the highest efficacy and selectivity, which was conditioned by a GLUT-1-mediated uptake. PeS-9 induced androgen receptor degradation followed by downregulation of its signaling. In addition, it increased reactive oxygen species production and induced DNA double-strand breaks. Combinational therapy with PARP inhibitor olaparib resulted in synergistic effects in homologous recombination-deficient cells. The underlying mode of PeS-9's cytotoxic action involved mitochondrial targeting, leading to a loss of mitochondrial membrane potential, release of cytochrome C and apoptosis-inducing factor, activation of caspases-3 and -9, PARP cleavage, and apoptotic cell death. This process was stipulated by downregulation of several antiapoptotic factors and induction of endoplasmic reticulum stress. Moreover, drug-induced activation of signaling pathway mediated by p38, JNK1/2, and ERK1/2 kinases was identified as an important factor of the cytotoxic activity. The anticancer activity of PeS-9 could be confirmed ex vivo using patient-derived tumoroids as well as in vivo in xenografts, demonstrating suppression of tumor growth and decreased dissemination of prostate cancer cells to the lungs. No serious side effects were observed in animal models. This unique combination of anticancer properties makes PeS-9 an attractive candidate for targeted monotherapy against GLUT-1-overexpressing tumors and as a potential combination partner, especially with PARP inhibitors.