Glutathione S‑transferase ω 1 promotes the proliferation, migration and invasion, and inhibits the apoptosis of non‑small cell lung cancer cells, via the JAK/STAT3 signaling pathway

Glutathione S‑transferase ω 1 (GSTO1) expression levels have been discovered to be upregulated in various types of cancer. However, to the best of our knowledge, the role of GSTO1 in non‑small cell lung cancer (NSCLC) has not been investigated. The present study aimed to investigate the role of GSTO1 in NSCLC and to determine the potential molecular mechanism. GSTO1 expression levels in A549 cells were knocked down using short hairpin RNA and GSTO1 overexpression in H2122 cells was achieved using cDNA constructs. Reverse transcription‑quantitative PCR was used to analyze the mRNA expression levels of GSTO1. Cell proliferation was determined using a Cell Counting Kit‑8 assay, whereas cell migration and invasion were analyzed using Transwell assays. Flow cytometric analysis was performed to determine the levels of cell apoptosis. The expression levels of GSTO1, Bax, caspase 3, JAK and STAT3 were analyzed using western blotting. The results revealed that GSTO1 overexpression significantly promoted the proliferation, migration and invasion, and inhibited the apoptosis of H2122 cells, whereas the opposite trend was achieved in A549 cells with GSTO1 knockdown. GSTO1 overexpression also significantly increased the phosphorylation levels of JAK and STAT3, whereas the knockdown of GSTO1 promoted the opposite effects. In conclusion, the findings of the present study indicated that GSTO1 may serve as an oncogene in NSCLC. The results suggested that GSTO1 may have an important role in NSCLC by regulating the JAK/STAT3 signaling pathway. Therefore, inhibiting the expression levels of GSTO1 may represent a potential novel therapeutic strategy for NSCLC.

Inhibition of Bcl-2 and Bcl-xL overcomes the resistance to the third-generation EGFR tyrosine kinase inhibitor osimertinib in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have demonstrated significant benefits to patients with non‑small cell lung cancer (NSCLC) harboring EGFR‑activating mutations; however, acquired resistance limits their long‑term efficacy. Therefore, it remains an urgent requirement to discover the underlying mechanisms and investigate novel therapeutic strategies for overcoming the resistance to EGFR TKIs. The present study aimed to determine the mechanism underlying the resistance of NSCLC cells to osimertinib, a third‑generation EGFR tyrosine kinase inhibitor, the osimertinib‑resistant NSCLC cell sub‑line HCC827/OR was established in the present study. It was found that the expression levels of Bcl‑2 and Bcl‑xL were significantly upregulated in resistant cells compared with sensitive cells. Furthermore, the suppression of Bcl‑2 and Bcl‑xL through small interfering RNA‑mediated gene knockdown or using a small molecule specific inhibitor ABT‑263 re‑sensitized HCC827/OR cells to osimertinib treatment. Moreover, the combined treatment of HCC827/OR cells with ABT‑263 and osimertinib enhanced the rate of cell apoptosis through the mitochondrial apoptotic pathway. Finally, ABT‑263 was able to overcome the resistance of osimertinib in xenograft tumor models. In conclusion, these findings may provide an improved concept for the development of a novel combined therapeutic strategy for the treatment of NSCLC resistance to EGFR TKIs.

Cancer type‑SLCO1B3 promotes epithelial‑mesenchymal transition resulting in the tumour progression of non‑small cell lung cancer

Non‑small cell lung cancer (NSCLC) is one of the most common histologically defined subtypes of lung cancer. To identify a promising molecular target for NSCLC therapy, we performed gene expression analysis at the exon level using postoperative specimens of NSCLC patients. Exon array and real‑time PCR analyses revealed that an alternative splicing variant of solute carrier organic anion transporter family member 1B3 (SLCO1B3) called cancer type‑SLCO1B3 (Ct‑SLCO1B3) was significantly upregulated in the NSCLC samples. SLCO1B3 expressed in the liver [liver type (Lt)‑SLCO1B3] was found to be localised in the cell membrane, whereas Ct‑SLCO1B3 was detected in the cytoplasm of NSCLC cells. RNAi‑mediated knockdown of Ct‑SLCO1B3 inhibited in vitro anchorage‑independent cell growth, cell migration, and in vivo tumour growth of A549 cells. Overexpression of Ct‑SLCO1B3 but not Lt‑SLCO1B3 upregulated anchorage‑independent cell growth and cell migration of NCI‑H23 cells. Mechanistically, Ct‑SLCO1B3 was found to regulate the expression of epithelial‑mesenchymal transition (EMT)‑related genes. The upregulation of E‑cadherin was discovered to be especially pivotal to phenotypes of Ct‑SLCO1B3‑suppressed A549 cells. These findings suggest that Ct‑SLCO1B3 functions as a tumour‑promoting factor via regulating EMT‑related factors in NSCLC.

Long non‑coding RNA PITPNA‑AS1 silencing suppresses proliferation, metastasis and epithelial‑mesenchymal transition in non‑small cell lung cancer cells by targeting microRNA‑32‑5p

Lung cancer is one of the most common types of cancer and has a high mortality rate, worldwide. The major histopathological subtype is non-small cell lung cancer (NSCLC). The aim of the present study was to investigate the role of long non-coding (lnc) RNA PITPNA antisense RNA 1 (PITPNA-AS1) in NSCLC and elucidate its potential mechanisms. The expression of PITPNA-AS1 was determined in several NSCLC cell lines. Following PITPNA-AS1-silencing, cell proliferation, invasion and migration were evaluated using Cell Counting Kit-8, colony formation, Transwell assay and wound healing assays, respectively. The expression levels of proliferation-, migration- and epithelial-mesenchymal transition (EMT)-associated proteins were examined using immunofluorescence assay or western blot analysis. A luciferase reporter assay was conducted to verify the potential interaction between PITPNA-AS1 and microRNA(miR)-32-5p. Subsequently, rescue assays were performed to investigate the effects of PITPNA-AS1 and miR-32-5p on NSCLC progression. The results demonstrated that PITPNA-AS1 was highly expressed in NSCLC tissues and cell lines. It was found that PITPNA-AS1 silencing inhibited the proliferation, invasion and migration of NSCLC cells. Furthermore, the protein expression of E-cadherin was upregulated, while the expression levels N-cadherin and vimentin were downregulated. The luciferase reporter assay confirmed that miR-32-5p was a direct target of PITPNA-AS1. The rescue experiments suggested that a miR-32-5p inhibitor significantly reversed the inhibitory effects of PITPNA-AS1 silencing on proliferation, invasion, migration and EMT in NSCLC cells. Collectively, the present results demonstrated that PITPNA-AS1 silencing could suppress the progression of NSCLC by targeting miR-32-5p, suggesting a promising biomarker in NSCLC diagnosis and treatment.