HOTAIR, a long intervening non-coding RNA (lincRNA), associates with the Polycomb Repressive Complex 2 (PRC2) and is reported to reprogram chromatin organization and promote tumor progression. However, little is known about the roles of this gene in the development of chemoresistance phenotype of lung adenocarcinoma (LAD). Thus, we investigated the involvement of HOTAIR in the resistance of LAD cells to cisplatin. In this study, we show that HOTAIR expression was significantly upregulated in cisplatin-resistant A549/DDP cells compared with in parental A549 cells. Knockdown of HOTAIR by RNA interference could resensitize the responses of A549/DDP cells to cisplatin both in vitro and in vivo. In contrast, overexpression of HOTAIR could decrease the sensitivity of A549 and SPC-A1 cells to cisplatin. We also found that the siRNA/HOTAIR1-mediated chemosensivity enhancement was associated with inhibition of cell proliferation, induction of G0/G1 cell-cycle arrest and apoptosis enhancement through regulation of p21WAF1/CIP1 (p21) expression. Also, pcDNA/p21or siRNA/p21 could mimic the effects of siRNA/HOTAIR1 or pcDNA/HOTAIR on the sensitivity of LAD cells to cisplatin. Importantly, siRNA/p21 or pcDNA/p21 could partially rescue the effects of siRNA/HOTAIR1 or pcDNA/HOTAIR on both p21 expression and cisplatin sensitivity in LAD cells. Further, HOTAIR was observed to be significantly downregulated in cisplatin-responding LAD tissues, and its expression was inversely correlated with p21 mRNA expression. Taken together, our findings suggest that upregulation of HOTAIR contributes to the cisplatin resistance of LAD cells, at least in part, through the regulation of p21 expression.

MicroRNAs (miRNAs) regulate gene expression by binding to target sites and initiating translational repression and/or mRNA degradation. In our previous study, we have shown that expression of serum microRNA (miR)-21 is correlated with TNM stage and lymph node metastasis and might be an independent prognostic factor for NSCLC patients. However, the roles of miR-21 overexpression in NSCLC development are still unclear. The purpose of this study is to investigate the effect of miR-21 and determine whether miR-21 can be a therapeutic target for human NSCLC. Taqman real-time quantitative RT-PCR assay was performed to detect miR-21 expression in NSCLC cell lines and tissues. Next, the effects of miR-21 expression on NSCLC cell characteristics including growth, invasion, and chemo- or radioresistance were also determined. Results showed that miR-21 is commonly upregulated in NSCLC cell lines and tissues with important functional consequences. In addition, we found that anti-miR-21 could significantly inhibit growth, migration and invasion, and reverse chemo- or radioresistance of NSCLC cells, while miR-21 mimics could increase growth, promote migration and invasion, and enhance chemo- or radioresistance of NSCLC cells. Meanwhile, miR-21 mimics could inhibit expression of PTEN mRNA and protein and the luciferase activity of a PTEN 3'-untranslated region (UTR)-based reporter construct in A549 cells, while anti-miR-21 could increase expression of PTEN mRNA and protein and the luciferase activity of a PTEN 3'-UTR-based reporter construct in A549 cells. Furthermore, overexpression of PTEN could mimic the same effects of anti-miR-21 in NSCLC cells, and siRNA-mediated downregulation of PTEN could rescue the effects on NSCLC cells induced by anti-miR-21. Taken together, these results provide evidence to show the promotion role of miR-21 in NSCLC development through modulation of the PTEN signaling pathway.

Recent studies of the individual functionalities of long non-coding RNAs (lncRNAs) in the development and progression of cancer have suggested that HOX transcript antisense RNA (HOTAIR) is capable of reprogramming chromatin organization and promoting cancer cell metastasis. In order to ascertain the expression pattern of the lncRNA HOTAIR and assess its biological role in the development and progression of esophageal squamous cell carcinoma (ESCC), HOTAIR expression in ESCC tissues and adjacent noncancerous tissues were collected from 78 patients and measured by real-time reverse transcription-polymerase chain reaction (RT-PCR). HOTAIR correlation with clinicopathological features and prognosis was also analyzed. Suppression of HOTAIR using siRNA treatment was performed in order to explore its role in tumor progression. Notably elevated HOTAIR expression levels were observed in cancerous tissues compared to adjacent noncancerous tissues (96%, P < 0.01), showing a high correlation with cancer metastasis (P < 0.01), elevated TNM (2009) stage classification (P < 0.01), and lowered overall survival rates (P = 0.003). Multivariate analysis revealed that HOTAIR expression (P = 0.003) is also an independent prognostic factor for comparison of TNM stage (P = 0.024) and lymph node metastasis (P = 0.010). Furthermore, in vitro assays of the ESCC cell line KYSE30 demonstrated that knockdown of HOTAIR reduced cell invasiveness and migration while increasing the response of cells to apoptosis. Thus, HOTAIR is a novel molecule involved in both ESCC progression and prognosis. Full elucidation of HOTAIR functionality relevant to ESCC may open avenues for the use of lncRNAs in identification of novel drug targets and therapies for ESCC and other prevalent cancers.

BackgroundNSCLC (non-small-cell lung cancer) is the leading cause of cancer-related mortality worldwide. Both epigenetic and genetic changes contribute to the initiation, development and metastasis of NSCLC. Recently, accumulating data have begun to support the notion that long noncoding RNAs (lncRNAs) function as new crucial regulators of diverse biological processes, including proliferation, apoptosis and metastasis, and play crucial roles in tumorigenesis. Nevertheless, further study is warranted to comprehensively determine lncRNAs' functions and potential mechanism.MethodsIn this study, we performed a comprehensive analysis of the lncRNA expression profile of NSCLC using data from TCGA and Gene Expression Omnibus (GEO). PCAT6 expression level in a cohort of 60 pairs of NSCLC tissues using quantitative real-time PCR (qRT-PCR). Additionally, Loss-of-function assays and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. Tumor formation assay in a nude mouse model was performed to verity the role of PCAT6 in NSCLC in vivo. Meanwhile, RIP, ChIP, resue experiment and western blot assays were used to highlights the potential molecular mechanism of PCAT6 in NSCLC.FindingsWe identified that an oncogene, PCAT6, was upregulated in NSCLC, and this upregulation was verified in a cohort of 60 pairs of NSCLC tissues. Additionally, the expression level of PCAT6 was correlated with tumor size (P = .036), lymph node metastasis (P = .029) and TNM stage (P = .038). Loss-of-function and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. The results revealed that PCAT6 knockdown mitigated NSCLC cell growth by inducing G1-phase cell cycle arrest and apoptosis in vitro and in vivo. Whereas, PCAT6 overexpression could promoted tumor cell growth. Meanwhile, PCAT6 additionally promoted NSCLC cell migration and invasion. Furthermore, mechanistic investigation demonstrated that the oncogenic activity of PCAT6 is partially attributable to its repression of LATS2 via association with the epigenetic repressor EZH2 (Enhancer of zeste homolog 2). Overall, our study highlights the essential role of PCAT6 in NSCLC, suggesting that PCAT6 might be a potent therapeutic target for patients with NSCLC.