Overexpression of Circular RNA ciRS‐7 Abrogates the Tumor Suppressive Effect of miR‐7 on Gastric Cancer via PTEN/PI3K/AKT Signaling Pathway

Gastric cancer (GC) has one of the highest mortality rates of malignancies globally. Currently, ciRS‐7, a novel circular RNA, has emerged as a potential sponge for miR‐7. However, few studies on ciRS‐7 in GC have been performed. In this study, we investigated the clinical significance and function of ciRS‐7 in GC. First, the expression levels of ciRS‐7 in 102 primary GC tissues and the matched para‐carcinoma tissues were evaluated and the clinical relevance was confirmed in an independent validation cohort (n = 154). Second, the effects of ciRS‐7 on miR‐7, PTEN, and PI3K were evaluated. Finally, the function of ciRS‐7 in GC was analyzed with cell lines and nude mice. The expression of ciRS‐7 was significantly upregulated in GC tissues compared with the matched para‐carcinoma tissues (P = 0.0023), and the upregulation of ciRS‐7 was linked to poor survival in the testing (P = 0.0143) and validation cohort (P = 0.0061). Multivariate survival analysis revealed that ciRS‐7 was probably an independent risk factor of overall survival (P < 0.05). Furthermore, overexpression of ciRS‐7 blocked the miR‐7‐induced tumor suppression in MGC‐803 and HGC‐27 cells and led to a more aggressive oncogenic phenotype, via antagonizing miR‐7‐mediated PTEN/PI3K/AKT pathway. ciRS‐7 may act as a prospective prognostic biological marker and a promising therapeutic target for GC. J. Cell. Biochem. 119: 440–446, 2018. © 2017 Wiley Periodicals, Inc.     

Long noncoding RNA HNF1A‐AS1 regulates proliferation and apoptosis of glioma through activation of the JNK signaling pathway via miR‐363‐3p/MAP2K4

Long noncoding RNAs (lncRNAs) have been proven to exert important functions in the various biological processes of human cancers. It has been reported that lncRNA HNF1 homeobox A antisense RNA 1 (HNF1A‐AS1) was abnormally expressed and played a role in the initiation and development of various human cancers. In this study, we confirmed that the expression level of HNF1A‐AS1 was increased in glioma tissues and cells. Knockdown of HNF1A‐AS1 inhibited cell proliferation and promoted cell apoptosis in glioma. Then, we disclosed the downregulation of miR‐363‐3p in glioma tissues and cell lines. The interaction between HNF1A‐AS1 and miR‐363‐3p was identified in glioma cells. Furthermore, an inverse correlation between HNF1A‐AS1 and miR‐363‐3p was observed in glioma tissues. Afterwards, we recognized that MAP2K4 was a direct target of miR‐363‐3p. The expression of MAP2K4 was negatively correlated with miR‐363‐3p while positively related to HNF1A‐AS1 in glioma tissues. We also found the regulatory effect of HNF1A‐AS1 on the MAP2K4‐dependent JNK signaling pathway. All findings indicated that HNF1A‐AS1 induces the upregulation of MAP2K4 to activate the JNK signaling pathway to promote glioma cell growth by acting as a miR‐363‐3p sponge.     

Overexpression of long noncoding RNA HOXA‐AS2 predicts an adverse prognosis and promotes tumorigenesis via SOX4/PI3K/AKT pathway in acute myeloid leukemia

Long noncoding RNAs (lncRNAs) play important roles in diverse cellular processes and carcinogenesis. Homeobox A cluster antisense RNA 2 (HOXA‐AS2) is a 1,048‐basepairs lncRNA located between human HOXA3 and HOXA4 genes, whose overactivation was previously found to promote the proliferation and invasion of solid tumors. However, its clinical and biological roles in acute myeloid leukemia (AML) remain unclear. This study showed that HOXA‐AS2 was overexpressed in AML patients. In addition, the increased HOXA‐AS2 expression was correlated with higher white blood cell and bone marrow blast counts, unfavorable karyotype classification, more measurable residual disease positivity, and earlier death. There was also a tendency toward inferior survival in patients with high HOXA‐AS2 expression, and HOXA‐AS2 was an independent prognostic factor among the normal‐karyotype AMLs. Furthermore, the results of in vitro study showed that silencing HOXA‐AS2 significantly inhibited the growth of leukemic cells by inducing G1/G0‐phase arrest and apoptosis. Further analysis demonstrated that silencing HOXA‐AS2 suppressed the phosphorylation level of PI3K and AKT, which thereafter promoted the expression of P21 and P27. Moreover, it was suggested that the sex‐determining region Y‐box 4 (SOX4), which is closely involved in the PI3K/AKT pathway, might be one of the major downstream targets of HOXA‐AS2. Silencing HOXA‐AS2 decreased the expression of SOX4, whereas the upregulation of SOX4 partially abrogated the inhibitory effect of silencing HOXA‐AS2 on leukemic cells. In conclusion, these findings suggest that HOXA‐AS2 probably functions as an oncogene via SOX4/PI3K/AKT pathway and might be a useful biomarker for the prognostic prediction in AML patients, providing a potential therapeutic target for AML.