Hydrogen gas promotes apoptosis of lung adenocarcinoma A549 cells through X-linked inhibitor of apoptosis and baculoviral inhibitor of apoptosis protein repeat-containing 3

Objective: Lung cancer is currently the cancer with the highest incidence and death toll worldwide. Hydrogen gas has been found to affect a variety of diseases; however, the effect of hydrogen gas on patients with lung cancer has not been reported. Therefore, we determined the effect of hydrogen gas on apoptosis of lung adenocarcinoma in vivo and in vitro. Materials and methods: A549 cells in the logarithmic phase were treated with 20%, 40%, or 60% hydrogen gas. Cell apoptosis was evaluated by flow cytometry. The A549 cell suspension was inoculated into 15 nude mice. The mice were randomly divided into control, hydrogenation (inhalation of 60% hydrogen gas), and cisplatin groups (intraperitoneal injection of cisplatin [4 mg/kg]). After 3 weeks, the tumor tissue was removed and measured. We identified differentially expressed genes by transcriptional profiling. The levels of X-linked inhibitor of apoptosis (XIAP), baculoviral inhibitor of apoptosis protein repeat-containing 3 (BIRC3), and BCL2-associated X and apoptosis regulator (BAX) protein expression were detected by Western blotting and immunohistochemistry. Results: Compared with the control group, the apoptosis rates in the 20%, 40%, and 60% hydrogen gas groups were significantly increased (P < 0.01). The levels of XIAP and BIRC3 protein expression were clearly decreased in the hydrogen gas group compared to the control group. Moreover, cisplatin and hydrogen gas reduced the tumor volume in nude mice (P < 0.01). Transcriptome sequencing showed that XIAP, BIRC2, BIRC3, BAX, PIK3CD, and ATM were related to apoptosis. Hydrogen gas further decreased the levels of XIAP and BIRC3 expression than in nude mice (P < 0.01). Conclusion: Hydrogen gas promoted apoptosis of A549 cells by reducing the expression of XIAP and BIRC3 protein.

Hydrogen gas inhibits lung cancer progression through targeting SMC3

Lung cancer is one of the most common lethal malignancies in the globe. The patients’ prognoses are dim due to its high metastatic potential and drug resistance. Therefore, in the present study, we aim to find a more potent therapeutic approach for lung cancer. We mainly explored the function of hydrogen gas (H2) on cell viability, apoptosis, migration and invasion in lung cancer cell lines A549 and H1975 by CCK-8, flow cytometry, wound healing and transwell assays, respectively. We used RNA-seq, qPCR and western blotting to detect the different expression genes (DEGs) between H2 group and control group to find the gene related to chromosome condensation. Besides, we confirmed the structural maintenance of chromosomes 3 (SMC3) and H2 on the progression of lung cancer in vitro and vivo. Results showed that H2 inhibited cell viability, migration and invasion, and catalyzed cell apoptosis and H2 induced A549 and H1975 cells G2/M arrest. Besides, H2 down-regulated the expression of NIBPL, SMC3, SMC5 and SMC6, and also reduced the expression of Cyclin D1, CDK4 and CDK6. H2 translocated the subcellular location of SMC3 during cell division and decreased its stability and increased its ubiquitination in both A549 and H1975 cells. In addition, inhibition of the proliferation, migration and invasion and promotion of the apoptosis of A549 and H1975 cells induced by H2 were all abolished when overexpressed SMC3 in the presence of H2. Animal experimental assay demonstrated that the tumor weight in H2 group was significantly smaller than that in control group, but was bigger than cis-platinum group. The expression of Ki-67, VEGF and SMC3 were decreased when mice were treated with H2 or cis-platinum, especially for cis-platinum. All data suggested that H2 inhibited lung cancer progression through down-regulating SMC3, a regulator for chromosome condensation, which provided a new method for the treatment of lung cancer.