Mining the Prognostic Role of DNA Methylation Heterogeneity in Lung Adenocarcinoma.

Purpose: DNA methylation heterogeneity is a type of tumor heterogeneity in the tumor microenvironment, but studies on the identification of the molecular heterogeneity of the lung adenocarcinoma genome with respect to DNA methylation sites and their roles in lung cancer progression and prognosis are scarce. Methods: Prognosis-associated DNA methylation subtypes were filtered by the Cox proportional hazards model and then established by unsupervised cluster analysis. Association analysis of these subtypes with clinical features and functional analysis of annotated genes potentially affected by methylation sites were performed. The robustness of the model was further tested by a Bayesian network classifier. Results: Over 7 thousand methylation sites were associated with lung adenocarcinoma prognosis. We identified seven molecular methylation subtypes, including 630 methylation sites. The subtypes yielded the most stable results for differentiating methylation profiles, prognosis, and gene expression patterns. The annotated genes potentially affected by these methylation sites are enriched in biological processes such as morphogenesis and cell adhesion, but their individual impact on the tumor microenvironment and prognosis is multifaceted. Discussion. We revealed that DNA methylation heterogeneity could be clustered and associated with the clinical features and prognosis of lung adenocarcinoma, which could lead to the development of a novel molecular tool for clinical evaluation.

Circ_0020123 regulates autophagy, glycolysis, and malignancy by upregulating IRF4 through eliminating miR-193a-3p-mediated suppression of IRF4 in non-small cell lung cancer.

Circular RNA is related to the tumorigenesis of various cancers. Circular RNA hsa_circ_0020123 (circ_0020123) has been uncovered to promote non-small cell lung cancer (NSCLC) progression. However, the regulatory mechanism of circ_0020123 in NSCLC is unclear. The quantitative real-time polymerase chain reaction was employed to detect the levels of circ_0020123, microRNA (miR)-193a-3p, and IRF4 interferon regulatory factor 4 (IRF4) in NSCLC tissues and cells. Loss-of-function experiments were performed to analyze the impacts of circ_0020123 silencing on NSCLC cell malignancy, autophagy, and glycolysis. Protein levels were detected using western blotting. The regulatory mechanism of circ_0020123 was analyzed by bioinformatics analysis and validated by the dual-luciferase reporter, RNA immunoprecipitation assay, and RNA pull-down assay. Xenograft assay was performed to verify the biological function of circ_0020123. We observed an overt elevation in circ_0020123 expression in NSCLC samples and cells, and NSCLC patients with high circ_0020123 expression had a poor prognosis. Circ_0020123 knockdown constrained xenograft tumor growth in vivo and curbed cell proliferation, migration, and glycolysis, and accelerated cell apoptosis and autophagy in NSCLC cells in vitro. Circ_0020123 could absorb miR-193a-3p to regulate IRF4 expression. miR-193a-3p silencing overturned circ_0020123 knockdown-mediated impacts on NSCLC cell malignancy, autophagy, and glycolysis. And IRF4 overexpression reversed miR-193a-3p mimic-mediated effects on NSCLC cell malignancy, autophagy, and glycolysis. Circ_0020123 promoted glycolysis and tumor growth by upregulating IRF4 through sequestering miR-193a-3p in NSCLC, offering a novel mechanism by which circ_0020123 is responsible for the malignancy, autophagy, and glycolysis of NSCLC cells.

Curcumin suppresses the stemness of non-small cell lung cancer cells via promoting the nuclear-cytoplasm translocation of TAZ.

Curcumin has been shown to suppress the progression of lung cancer, however, the underlying mechanisms are largely unknown. Here, we aimed to investigate the effects of curcumin on the stemness of non-small cell lung cancer (NSCLC) cells. We found that curcumin reduced the sphere formation ability at the concentrations without affecting the cell viability of NSCLC cells and normal pulmonary epithelial cells, which is evident by the decrease of sphere size and number. In addition, curcumin decreased ALDH activity and the expression of stemness markers (CD133, EpCAM, Oct4). RNA sequencing analysis revealed that the Hippo pathway was mostly enriched in cells with curcumin treatment. Indeed, the expression of cancer stem cell markers was significantly decreased by curcumin treatment by analyzing the RNA sequencing data. Gene set enrichment analysis (GSEA) showed that curcumin negatively regulated the cancer stem cell function and positively modulated cancer stem cell differentiation ability. Furthermore, curcumin enhanced the cisplatin sensitivity of NSCLC cells. Mechanistically, it was found that curcumin promoted the nuclear-cytoplasm translocation of TAZ, but not YAP, the critical effectors of Hippo pathway. In addition, curcumin destabilzed TAZ protein stability and promoted TAZ protein degradation in lung cancer cells, which is dependent on the proteasome degradation system, not by autophagy lysosome degradation system. Overexpression of TAZ rescued the inhibition of curcumin on the stemness of lung cancer cells. Thus, our results suggest that curcumin can attenuate the stemness of lung cancer cells through promoting TAZ protein degradation and thus activating Hippo pathway.

MiR-199a-5p-HIF-1α-STAT3 Positive Feedback Loop Contributes to the Progression of Non-Small Cell Lung Cancer.

Background: Non-small cell lung cancer (NSCLC) is the most common malignancy worldwide. MiR-199a-5p has been reported to play important roles in multiple tumors, inclusive of NSCLC. However, little is definitively known pertaining to its explicit mechanism of action in NSCLC. Methods: The expressions of miR-199a-5p and hypoxia-inducible factor-1α (HIF-1α) mRNA were quantified employing qRT-PCR. H1299 and A549 cells were transiently transfected with miR-199a-5p mimics or inhibitors. Then, CCK-8 assays, flow cytometry analysis, and Transwell assay were performed for detecting cell proliferation, cell cycle, apoptosis, migration, and invasion of NSCLC cells, respectively. HIF-1α, signal transducer and activator of transcription 3 (STAT3), and p-STAT3 expressions were detected via Western blotting. Bioinformatic analysis and dual-luciferase assay were performed to investigate the interactions among miR-199a-5p, HIF-1α, and STAT3. Xenograft models were established with nude mice for further analyzing the bevacizumab resistance of NSCLC cells. Results: MiR-199a-5p expression was markedly attenuated in NSCLC tissues and cell lines. Overexpression of miR-199a-5p repressed the proliferation, migration, and invasion but induced the apoptosis of NSCLC cells. HIF-1α was identified as a direct target of miR-199a-5p. There was a positive feedback loop among miR-199a-5p, HIF-1α, and STAT3. Co-transfection of HIF-1α or STAT3 overexpression plasmids counteracted the effects of miR-199a-5p. In vivo experiments indicated that the feedback loop was in association with the bevacizumab resistance of NSCLC cells. Conclusion: MiR-199a-5p blocked the progression of NSCLC and sensitized NSCLC cells to bevacizumab by suppressing HIF-1α and STAT3, while the HIF-1α/STAT3 axis suppressed the expression of miR-199a-5p, which forms a positive feedback loop to promote the sustaining progression of NSCLC.