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Laryngeal squamous cell carcinoma (LSCC), one of the most common malignant solid tumors in the world, has a high rate of mortality, recurrence, and metastasis. Recombinant human arginase (rhArg) recently has been developed in arginine deprivation therapy for a number of malignant tumors. In the present study, we observed that rhArg triggered significant cytotoxicity in human laryngeal squamous cell carcinoma Tu212 cells. Meanwhile, we observed that rhArg simultaneously activated autophagic flux in Tu212 cells, which was demonstrated by the accumulation of autophagosome and light chain 3 II (LC3-II). And, we explored the role of autophagy in cytotoxicity induced by rhArg in Tu212 cells. Autophagy inhibitors including chloroquine (CQ) and bafilomycin A1 (Baf A1) enhanced cytotoxicity induced by rhArg, implying the protective role of autophagy in rhArg-treated Tu212 cells. Moreover, Akt/mTOR signaling pathway was most possibly to participate in the rhArg-induced autophagy. Meanwhile, rhArg could upregulate the phosphorylation of ERK1/2 in a time-dependent manner. Therefore, all the results illuminated the cytoprotective role of autophagy in the treatment of rhArg in laryngeal squamous carcinoma Tu212 cells and provided a potential approach for LSCC therapy by rhArg combined with autophagy inhibitors. [ABSTRACT FROM AUTHOR]

Nedaplatin, a cisplatin analog, was developed to reduce the toxicity of cisplatin, whereas it can be cross-resistant with cisplatin in some circumstances. This study aimed to investigate the role of autophagy in nedaplatin induced cell death in cisplatin-resistant nasopharyngeal carcinoma cells. Here, we showed that HNE1/DDP and CNE2/DDP cells were resistant to nedaplatin-induced cell death with reduced apoptotic activity. Nedaplatin treatment resulted in autophagosome accumulation and increased expression of LC3-II, indicating the induction of autophagy by nedaplatin in HNE1/DDP and CNE2/DDP cells. Inhibition of autophagy by Bafilomycin A1 (Baf A1) and 3-Methyladenine (3-MA) remarkably enhanced the antitumor efficacy of nedaplatin in HNE1/DDP and CNE2/DDP cells, suggesting that the resistance to nedaplatin-induced cell death was caused by enhanced autophagy in nedaplatin-resistant NPC cells. Additionally, Baf A1 enhanced reactive oxygen species (ROS) generation and apoptosis induced by nedaplatin in HNE1/DDP cells. Mechanistically, nedaplatin treatment caused activation of ERK1/2 and suppression of Akt/mTOR signaling pathways. While inhibition of ERK1/2 by MEK1/2 inhibitor, U0126, could reduce the expression of LC3-II in nedaplatin-resistant NPC cells. Furthermore, suppression of ROS could inhibit nedaplatin-induced ERK activation in HNE1/DDP cells, indicating that ROS and ERK were involved in nedaplatin-induced autophagy. Together, these findings suggested that autophagy played a cytoprotective role in nedaplatin-induced cytotoxicity of HNE1/DDP and CNE2/DDP cells. Furthermore, our results highlighted a potential approach to restore the sensitivity of cisplatin-resistant nasopharyngeal cancer cells to nedaplatin in combination with autophagy inhibitors. [ABSTRACT FROM AUTHOR]