081 | Redox imbalance and ER stress mediate the anti-cancer effects of quinoline-based derivatives in triple-negative breast cancer cells

Chiara Occhipinti¹, Gabriele La Monica², Federica Alamia², Alessia Bono², Antonino Lauria², Annamaria Martorana², Antonella D’Anneo¹ | ¹Department of Biological, Chemical and Pharmaceutical Sciences and Technologies STEBICEF, Laboratory of Biochemistry, University of Palermo, Italy; ²Department of Biological, Chemical and Pharmaceutical Sciences and Technologies STEBICEF, University of Palermo, Italy.

Triple-negative breast cancer (TNBC) represents one of the most aggressive forms of breast cancer characterized by marked molecular heterogeneity, high metastatic potential, and poor prognosis. Moreover, the absence of hormone receptor (ER and PR) and HER2 expression, together with its rapid progression, renders TNBC poorly responsive to conventional therapies. [1]. Taking into account this complex scenario, this study focused on the evaluation of a library of 4-piperazinylquinoline derivatives in MDA-MB-231 cells, a highly aggressive triple-negative breast cancer model. Among the tested compounds, three derivatives showed a marked cytotoxic effect, characterized by a clear dose-dependent response. This effect was further supported by phase-contrast microscopy observations, which revealed pronounced morphological alterations and a high rate of cell death at the highest dose. Interestingly, pre-incubation with the antioxidant agent N-acetylcysteine (NAC) followed by treatment with the three compounds counteracted the effects induced by the compounds alone, suggesting that their activity may be related to the induction of oxidative events. Indeed, these compounds induced a remarkable increase in intracellular ROS levels after 24 h of incubation, activating Keap-1/Nrf2/HO-1 signaling pathway. Western blot analyses, revealed that all three compounds induced a decrease in Keap1, increased Nrf2 expression, and promoted the consequent upregulation of HO-1, a well-known Nrf2 transcriptional target. Furthermore, western blot analyses showed that treatment with the three compounds induced endoplasmic reticulum stress, as evidenced by the upregulation of GRP78 and CHOP proteins. Based on the marked reduction in cell viability observed at the highest concentration, specifically, Annexin V–based flow cytometric analysis revealed a significant accumulation of both early and late apoptotic cells, accompanied by caspase-3 activation and PARP1 cleavage. Interestingly, treatment with the three compounds also led to a decrease in p53 protein, which is mutated in this breast cancer cell line [2]. Overall, these findings demonstrate that quinoline-based derivatives induce oxidative stress–mediated apoptosis in TNBC cells, supporting further studies aimed at better elucidating their mechanism of action and identifying new potential targets.