Deprivation of asparagine triggers cytoprotective autophagy in laryngeal squamous cell carcinoma

Abstract

Laryngeal squamous cell carcinoma (LSCC), one of the most common malignancies in the head and neck, has poor prognosis and high mortality. The need of novel and effective treatment for LSCC is urgent. Asparaginase, an enzyme-depriving asparagine, has been employed for the treatment of various cancers. In this study, we reported for the first time that asparaginase could induce remarkable cytotoxicity and caspase-dependent apoptosis in human LSCC Tu212 and Tu686 cells. Meanwhile, autophagy was triggered by asparaginase in LSCC cells, which was confirmed by accumulation of autophagosomes and the conversion of light chain 3-I (LC3-I) to LC3-II. Importantly, inhibition of autophagy by chloroquine (CQ) significantly enhanced asparaginase-induced cytotoxicity, indicating that autophagy has a cytoprotective role in asparaginase-treated LSCC cells. Meanwhile, we found that mitochondrial-originated reactive oxygen species (ROS) participated in asparaginase-induced autophagy and cytotoxicity. N-acetyl-L-cysteine (NAC), a common antioxidant, was employed to scavenge ROS, and our results demonstrated that NAC could significantly block asparaginase-induced autophagy and attenuate asparaginase-induced cytotoxicity, indicating that intracellular ROS played a crucial role in asparagine deprivation therapy. Furthermore, western blot analysis showed that asparaginase-induced autophagy was mediated by inactivation of Akt/mTOR and activation of the Erk signaling pathway in Tu212 and Tu686 cells. Therefore, these results indicated the protective role of autophagy in asparaginase-treated LSCC cells and provided a new attractive therapeutic strategy for LSCC by asparaginase alone or in combination with autophagic inhibitors.

Targeting the autophagy promoted antitumor effect of T-DM1 on HER2-positive gastric cancer

“…NCI-N87 cells were treated with 1.25 µg/mL T-DM1, respectively, for the indicated times, and then stained with Cyto-ID, Hoechst 33342, and/or LysoTracker according to previously described instructions and analyzed with a confocal microscope (Carl Zeiss LSM710, Carl Zeiss, Germany) 50 . Rapamycin (50 nM) was used as the positive control.…”

An autophagy-related model of 4 key genes for predicting prognosis of patients with laryngeal cancer

“…[ 1 , 5 , 18 , 20 ] Exploration of the autophagy mechanism would open a new positive outlook for laryngeal cancer. [ 17 , 19 , 29 ] However, most researches focused on autophagy only analyzed a signal gene or an autophagic inhibitor. Garcia-Mayea et al performed an immunohistochemistry study to identify the putative relevance of autophagy in laryngeal cancer.…”

“…Ji et al also indicated the protective role of autophagy in laryngeal cancer cells and provided a new attractive therapeutic strategy for laryngeal cancer with autophagic inhibitors. [ 19 ] Also, Lin et al and Cao et al both proved the protective role of autophagy in laryngeal cancer. [ 18 , 20 ]…”

Combining use of Phillyrin and autophagy blocker alleviates laryngeal squamous cell carcinoma via AMPK/mTOR/p70S6K signaling

“…Moreover, some studies have demonstrated that anti-tumor drugs could trigger potent autophagy thereby affecting the drug effect [24]. Therefore, many studies have combined anti-tumor drugs with autophagy inhibitors to achieve the desired therapeutic effect [25,26]. In this study, we hypothesized that treatment with PHN alone or combined with an autophagy inhibitor could be a potential therapeutic strategy against LSCC.…”