Lung cancer, with the highest morbidity and second highest death rates, is one of the most common cancers in both males and females worldwide. Lung adenocarcinoma (LAD) is the main lung cancer class. KCNQ1 Opposite Strand/Antisense Transcript 1 (KCNQ1OT1) gene is an lncRNA which had been reported high-expression in colorectal cancer. In this study, the expression of KCNQ1OT1 was confirmed to be highly expressed in LAD tissues and cells contrast to control tissues and cells, and high KCNQ1OT1 expression correlated to malignant behaviors of LAD, including big tumor size, poor differentiation, positive lymphatic metastasis and high TNM stages. The transfection of si-KCNQ1OT1 could effectually knockdown the expression of KCNQ1OT1 in A549 and A549/PA cells. The KCNQ1OT1 knockdown depressed the proliferation and invasion of A549 cells, and advanced cellular apoptosis of A549 cells. The expression of KCNQ1OT1 in LAD patients insensitive to paclitaxel was much higher than that in LAD patients sensitive to paclitaxel; the KCNQ1OT1 expression in A549/PA cells was also much higher than that in control A549 cells. The half maximal inhibitory concentration (IC50) of paclitaxel in A549/PA cells was depressed by KCNQ1OT1 knockdown, chemoresistance of A549/PA cells was inhibited significantly. KCNQ1OT1 knockdown also depressed the expression of multidrug resistance 1 (MDR1) protein in A549/PA cells. In summary, lncRNA KCNQ1OT1 was highly expressed in LAD and functioned as a potential oncogene to inhibit malignancy and chemoresistance of LAD cells, which might be a novel potential therapeutic target for LAD.

Acetylcholine (ACh), which can be synthesized and secreted by cancer cells, has been reported to play an important role in tumor progression. ACh acts its role through activation of its receptors, muscarinic receptor (mAChR), and nicotinic receptor (nAChR). As a member of mAChR, M3 muscarinic receptor (M3R) is often highly expressed in many cancers. Activation of M3R by ACh participates in the proliferation, differentiation, transformation, and carcinogenesis of cancer. However, the effect of M3R activation on non-small cell lung cancer (NSCLC) remains unclear. Here, our study found that ACh dose-dependently promoted the proliferation, invasion, and migration of NSCLC cells. After silencing of M3R, the biological functions of ACh in NSCLC cells were greatly attenuated. Furthermore, ACh stimulation increased the production of IL-8 and time-dependently induced the activation of EGFR, PI3K, and AKT through M3R. In addition, ACh stimulated the activation of PI3K and AKT via EGFR activity, and blocking of PI3K/AKT pathway by special inhibitor LY294002 suppressed the ACh-mediated proliferation, invasion, and migration of NSCLC cells. Taken together, these findings indicate that activation of M3R by ACh enhances the proliferation, invasion, and migration of NSCLC cells. ACh-induced activation of EGFR/PI3K/AKT pathway and subsequent IL-8 upregulation may be one of the important mechanisms of M3R function. Thus, M3R could be a potential therapeutic target for the treatment of NSCLC.

5-Fu is a pyrimidine analog which is wildly used in the treatment of cancers. The development of strategies that increase its anticancer activity has been studied over the past 20 years. Despite these advances, drug resistance remains a significant limitation to the clinical use of 5-FU. In this study, we investigate the glucose metabolic profiles of non-small cell lung cancer cells in response to 5-Fu and cisplatin. Interestingly, the glucose metabolism of A549 cells is activated by 5-Fu treatment but suppressed by cisplatin treatment. We generalize 5-Fu-resistant and cisplatin-resistant cell lines from A549 cells. The glucose metabolism in 5-Fu-resistant cells is increased but decreased in cisplatin-resistant cells. In addition, glycolysis inhibition sensitizes lung cancer cells to 5-Fu. Importantly, we report a synergistic inhibitory effect on lung cancer cells by the combination of 5-Fu with cisplatin through the suppression of glucose metabolism both in vitro and in vivo. Moreover, restoration of glucose metabolism by overexpression of glycolytic key enzymes renders A549 cells resistant to 5-Fu. In summary, our study indicates that glycolysis inhibition contributes to the synergistic antitumor effect of combinational therapy, and targeting glycolysis could be an effective strategy for overcoming 5-Fu resistance in cancer therapy.

No abstract

Response gene to complement 32 (RGC32) is a novel protein originally identified as a cell cycle activator and has been demonstrated to be overexpressed in a variety of human malignancies, including lung cancer. However, the potential role of RGC32 in lung cancer initiation and progression remains to be elucidated. In the present study, RNA interference mediated by plasmid expressing RGC32 short-hairpin RNA (shRNA) was utilized to knockdown RGC32 expression in human lung cancer LTE cells. We found that the mRNA and protein expression levels of RGC32 were significantly decreased in RGC32-specific shRNA-transfected cells in comparison with the untransfected and control shRNA-transfected cells. Furthermore, knockdown of RGC32 dramatically reduced cell proliferation, colony formation, and invasion and migration capacities of LTE cells in vitro. Specific down-regulation of RGC32 caused G0/G1 cell cycle arrest and eventual apoptosis. Meanwhile, Western blot analysis indicated that cells with stably knockdown of RGC32 showed decreased expression levels of Cyclin D1, Cyclin E, Bcl-2, matrix metalloproteinase (MMP)-2, and MMP-9, but increased expression levels of activate caspase-3, Bax, and cleaved poly (ADP-ribose) polymerase (PARP) in comparison with control shRNA-transfected cells. Taken together, our data suggest that RGC32 is involved in tumorigenesis of human lung cancer and may serve as a promising therapeutic target for lung cancer.

The competing endogenous RNA (ceRNA) network is crucial for the development and progression of tumors, including non-small cell lung cancer (NSCLC). However, what type of ceRNA network regulates NSCLC has not been clarified. The present study aimed to elucidate the long non-coding RNA (lncRNA)/microRNA (miRNA)/mRNA ceRNA network in NSCLC, particularly for the significance of lncRNAs in NSCLC. NSCLC-specific differentially expressed lncRNAs, miRNAs and mRNAs in the Cancer Genome Atlas (TCGA) were analyzed and their relationship was analyzed by a ceRNA network. Their potential functions of differentially expressed mRNAs were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, the expression levels of four selected lncRNAs in TCGA were determined and their associated survival of patients was examined. In addition, the expression profiles of these four lncRNAs in 48 NSCLC specimens and cell lines, their cellular distribution and associated clinical parameters were examined. We successfully constructed a ceRNA network, including 113 lncRNAs, 12 miRNAs and 36 mRNAs differentially expressed between NSCLC and non-tumor tissues. LINC00525, MED4-AS1, STEAP2-AS1 and SYNPR-AS1 lncRNAs were selected and validated for their association with the survival of NSCLC patients. The expression of these lncRNAs was upregulated in 48 NSCLC tissues and was varying in NSCLC cells. While LINC00525 was mainly expressed in the cytoplasm, MED4-AS1 was in both the nucleus and cytoplasm of A549 cells. In addition, the expression of LINC00525 was significantly associated with smoking history (P<0.05); MED4-AS1 was significantly associated with women, poor differentiation and lymph node metastasis (P<0.05); STEAP2-AS1 was significantly associated with women (P<0.01); and SYNPR-AS1 was significantly associated with women and adenocarcinoma (P<0.05). These lncRNAs may be valuable biomarkers for prognosis of NSCLC and the ceRNA network may provide new insights in the pathogenesis of NSCLC.

Edited by Lukas Huber Keywords:Zinc finger and BTB domain-containing 20 FoxO1 Non-small cell lung cancer Cell cycle a b s t r a c tIn the present study, we found that ZBTB20, a member of the POK (POZ and Krüppel) family of transcriptional repressors, was significantly up-regulated in lung cancer tissues, compared with adjacent normal tissues. Our in vitro studies further found that ZBTB20 overexpression promoted, while its inhibition using small interfering RNA suppressed cell proliferation. Consistently, key regulators in cell-cycle progression, such as Cyclin D1, Cyclin E, P21 and P27, were also regulated by ZBTB20. At the molecular level, we further revealed that FoxO1, a tumor suppressor in multiple human cancers, was transcriptionally repressed by ZBTB20. Therefore, our results highlight an important role for ZBTB20 in controlling NSCLC development, which might be helpful to identify potential therapeutic targets for its treatment.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.