Multimodal cell death induced by indirubin-3'-oxime through inhibition of Akt/mTOR axis in lung cancer cells.

Lung cancer is a major type of malignancy that has contributed to a high mortality rate for many years. Discovering new small molecules with strong cytotoxic effects on lung cancer is crucial for developing new therapies. In this study, we describe the synthesis of a novel triazole-indirubin-3'-oxime derivative (designated as CRM1) and examine its ability to induce distinct forms of cell death, as well as elucidate the cytotoxicity-associated molecular mechanisms in lung cancer cells. CRM1 selectively reduced cell viability in lung cancer cell lines (A549, PC9, and H1299) without significantly affecting the viability of normal lung cells (HEL299). Mechanistic investigations have demonstrated that CRM1 induces paraptosis through the downregulation of Alix and the upregulation of ATF4 and CHOP. This process is associated with disruption of mitochondrial membrane potential, induction of endoplasmic reticulum stress, and accumulation of reactive oxygen species (ROS). CRM1 was observed to induce apoptosis, as indicated by DNA fragmentation, an increase in Sub-G1 cell population, as well as elevated caspase-3 cleavage and Bax expression. CRM1 also promoted autophagy, as evidenced by increased expression of Atg7, phosphorylated Beclin-1, and LC3-II, as well as enhanced autophagosome formation. Pharmacological inhibition studies confirmed the independent induction of apoptosis, paraptosis, and autophagy. Pre-exposure of cancer cells to N-acetyl cysteine abrogated CRM1-induced cytotoxicity. Mechanistic studies demonstrated that CRM1 suppresses the activation of Akt, mTOR, and p70S6K, while the overexpression of Akt counteracts the CRM1-driven cytotoxic effects. CRM1 also synergistically potentiated the cytotoxic efficacy of paclitaxel by co-targeting multiple cell death processes. Collectively, these results suggest CRM1 as a promising cytotoxic candidate with a multimodal mechanism of action in lung cancer cells.