Design and synthesis of novel quinazolinone-based pyruvate kinase M2 activators as selective inhibitors of oral cancer cells

Abstract

This study aims at fostering and uplifting the profile of tumor pyruvate kinase M2 (PKM2) modulators via development of novel, effective and selective agents against oral cancer cells. Towards this end, we designed and synthesized a novel and skeletally diverse library of quinazolinones. Notably, five of the newly synthesised compounds significantly reduced the cell viability of oral cancer cells (CAL 27) when compared to the normal oral epithelial (NOE) cells. In the lactate dehydrogenase (LDH)-coupled enzyme assay, the derivatives (17n, 17x and 17z) showed a potent PKM2 activation profile with IC50 values ranging from 14 μM to 26 μM. Of note, these three PKM2 activators displayed enhanced apoptotic effect on CAL 27 cells as analysed by the increased chromatin condensation, nuclear fragmentation and apoptotic bodies observed with Hoechst 33342 and annexin V-PI staining following fluorescent microscopy. This was corroborated by the enhancements in the mRNA expression of caspase 3 which is the final death-executioner. Additionally, flow cytometry analysis revealed that compound 17n killed CAL 27 cancer cells by cell cycle arrest in the G2/M phase. The computational studies revealed that these molecules preferentially interact with PKM2 at dimeric interface site similar to the reported PKM2 modulators and exhibit similar binding pattern. Overall, our results provide conclusive evidence that the quinazolinones possess strong anti-proliferative effects on CAL 27 cells with minimal toxicity towards NOE cells at similar concentrations and induced apoptotic machinery via caspase-3 dependent pathway. Hence, these PKM2 activators may serve as potential hits for further development as anti-cancer agents.