Synthesis and evaluation of tetrahydroquinolin-2(1H)-one derivatives as novel anti-pancreatic cancer agents via targeting autophagy

Abstract

Pancreatic cancer is one of the most deadly neoplasm with a 5-year survival rate of less than 6% owing to its remarkable tolerance to nutrient starvation, and new drugs and treatment strategies are urgently needed. During a project aiming at discovery of anticancer agents, we performed a structure modification on polycyclic polyprenylated acylphloroglucinols (PPAPs) skeleton, and discovered that PPAP rearranged to a tetrahydroquinolin-2(1H)-one feature. Here, series of tetrahydroquinolin-2(1H)-one derivatives were designed, synthesized and evaluated against a highly metastatic human pancreatic cancer cell line (PANC-1), and the structure-activity relationship was also discussed. Among them, derivative 11k showed the most potent inhibitory activity with an IC₅₀ value of 4.9 μM under nutrient-deprived condition. In contrast, all these derivatives exhibited low cytotoxicity against PANC-1 cells under normal nutrient condition, suggesting that the derivatives appeared to allow alternative tumor cell death mechanisms, and led to less toxicity. Further evaluations demonstrated that 11k decreased colony formation and induced the apoptosis of PANC-1 under nutrient-deprived condition in a concentration dependent manner. In in vivo study, 11k significantly suppressed the tumor development and weight in nude mice. Preliminary mechanism research revealed that 11k clearly downregulated LC3-II expression and increased the level of p62, two key autophagy markers and critical signals for pancreatic tumor growth and progression. Our current findings demonstrated that 11k might be a promising candidate for the new chemotherapeutic molecule of pancreatic cancer, and deserve further study.

Keywords: Autophagy; Inhibitors; PANC-1; Pancreatic cancer; Tetrahydroquinolin-2(1H)-one derivatives.