RESUMEN
Background: The aim of this study was to investigate the effect of DNA methylation of Fork Head Box O3 (FOXO3a) on the process of epithelial-mesenchymal transition (EMT) in non-small cell lung cancer (NSCLC). Methods: The expressions of FOXO3a, DNA methyltransferase 1 (DNMT1), METTL3, and EMT-related proteins (E-cadherin and N-cadherin) were measured. The influence of 5-Aza-dC and DNMT1 on the methylation level in the promoter region of FOXO3a was examined through the application of methylation-specific PCR (MSP). Chromatin immunoprecipitation (ChIP) was employed to detect binding between DNMT1 and the FOXO3a promoter. Methylated RNA immunoprecipitation (MeRIP) was utilized to evaluate the level of DNMT1 N6-methyladenosine (m6A) methylation. The assessment of cell viability and invasion abilities of A549 cells was performed using Cell Counting Kit-8 (CCK-8) and Transwell assays, respectively. NSCLC xenograft mouse models were established by subcutaneously injected treated A549 cells into nude mice. Results: The expression levels of DNMT1 and DNA methylation level FOXO3a were found to be significantly increased, whereas FOXO3a expression was considerably decreased in NSCLC cell lines and NSCLC tumor tissues. Both 5-Aza-dC treatment and DNMT1 knockdown resulted in the down-regulation of DNA methylation levels of FOXO3a while simultaneously up-regulating the expression of FOXO3a. A ChIP assay demonstrated that DNMT1 has the ability to bind to the promoter region of FOXO3a. Furthermore, the knockdown of DNMT1 promoted E-cadherin expression, but inhibited expression of N-cadherin, cell viability, and invasion ability. However, the knockdown of FOXO3a hindered the effect of DNMT1 knockdown on EMT, cell viability, and invasion ability of A549 cells. This was evidenced by decreased E-cadherin expression and increased N-cadherin expression, as well as increased cell viability and invasion ability. Increased expression of DNMT1 resulted from m6A methylation of DNMT1, which was mediated by METTL3. Overexpression of DNMT1 decreased of E-cadherin expression while increased N-cadherin expression, cell viability, and invasion ability in METTL3-shRNA treated A549 cells. In xenograft mouse models, DNMT1 knockdown significantly reduced tumor volumes and tumor weight. DNMT1 knockdown upregulated the expression of FOXO3a and E-cadherin, while downregulated N-cadherin expression in vivo. Conclusion: METTL3-mediated m6A methylation of DNMT1 up-regulates FOXO3a promoter methylation, thereby promoting the progression of NSCLC.
RESUMEN
Objective: To assess the clinical efficacy of thoracoscopic surgery with the da Vinci surgical system versus video-assisted thoracoscopic surgery (VATS) for lung cancer. Methods: From August 2019 to December 2020, 193 patients with lung cancer assessed for eligibility scheduled for surgery in our hospital were recruited and assigned at a ratio of 1 : 1 to receive VATS (control group) or thoracoscopic surgery with the da Vinci surgical system (research group). The primary measurement is the clinical efficacy of the two surgical modalities. Results: The baseline features of the research group were comparable with those of the control group (P > 0.05). Besides, the two groups showed similar tumor types, tumor locations, and clinicopathological staging (P > 0.05). Da Vinci surgical system-assisted thoracoscopic surgery had short operative time, less intraoperative blood loss, better lymph node dissection, and lower intraoperative conversion rates compared to VATS. Compared with the control group, the research group had significantly higher postoperative forced expiratory volume in one second (FEV1), forced vital capacity (FVC), maximal voluntary ventilation (MVV), the functional assessment of cancer therapy-general module (FACT-G) of the FACT-lung (FACT-L) Chinese version V4.0, lung cancer-specific module scores, and total scores (P < 0.05). The research group showed better postoperative drainage volume, shorter intubation duration, and length of hospital stay and a lower incidence of complications versus the control group (P < 0.05). The da Vinci surgical system reduced the probability of intraoperative mistakes and better ensured a safe and satisfactory surgery. Conclusion: The thoracoscopic surgery with the da Vinci surgical system better reduces intraoperative and postoperative bleeding, shortens drainage and intubation duration, enhances the lung function and survival quality of patients, and lowers the risk of surgical mistakes to ensure surgical safety versus VATS.