Long noncoding RNA SNHG6 regulates p21 expression via activation of the JNK pathway and regulation of EZH2 in gastric cancer cells.

Increasing evidence suggests that long noncoding RNAs act as critical regulators in various malignancies. Small nucleolar RNA host gene 6 (SNHG6) plays a role in the progression of human cancers. The present study aims to investigate the molecular mechanism through which SNHG6 promotes the development of gastric cancer (GC). The expression level of SNHG6 in human serum was examined using reverse transcription and quantitative polymerase chain reaction (qRT-PCR). RNA- fluorescence in situ hybridization (FISH) and Cell nucleus/cytoplasm fraction isolation assay were used to detect the cellular distribution of SNHG6. Senescence-associated β-galactosidase (SA-β-gal) activity assay was performed to detect cell senescence. BALB/c male nude mice were used to establish the xenograft model. We found that SNHG6 was up-regulated in human GC tissues and serum. Knockdown of SNHG6 inhibited GC cell proliferation, induced cellular senescence, and reduced xenograft tumor growth in BALB/c nude mice. Knockdown of SNHG6 stimulated p21 expression and the tumor-suppressive effect of SNHG6 in GC cells was dependent on p21. Furthermore, the activation of the c-Jun N-terminal kinase (JNK) pathway and the decrease in Enhancer of Zeste Homolog 2 (EZH2) expression levels represented two mutually independent mechanisms by which SNHG6 knockdown resulted in the upregulation of p21. Our findings show that SNHG6 knockdown inhibits GC development by upregulating p21; this effect is dependent on the activation of the JNK pathway and suppression of EZH2 expression. This study indicates that SNHG6 plays an important role in GC progression via the regulation of 21.

Li Y ，Li D ，Zhao M ，Huang S ，Zhang Q ，Lin H ，Wang W ，Li K ，Li Z ，Huang W ，Che Y ，Huang C ... -  《-》

SNHG6 Promotes Tumor Growth via Repression of P21 in Colorectal Cancer.

SNHG6 (Small Nucleolar RNA Host Gene 6) is a novel non-coding RNA (ncRNA) and its cellular function is largely unknown. Cell Counting Kit-8 (CCK-8) cell growth assay, colony formation and flow cytometry were used to determine colorectal cancer cell proliferation, cell cycle progression and apoptosis in vitro. The xenograft tumor formation assay in nude mice was established to evaluate tumor growth in vivo. RNA immunopreciptation (RIP) analysis was performed to examine whether SNHG6 could bind to EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit), and chromatin immunoprecipitation (ChIP) assay was conducted to examine whether SNHG6 could repress p21 transcription by recruiting EZH2 to the p21 promoter. Here we found that SNHG6 was upregulated and its expression levels were positively correlated with advanced tumor stage in colorectal cancer. Survival analysis suggested that higher expression of SNHG6 predicted poor prognosis in patients with colorectal cancer. Functional studies indicated that SNHG6 could promote cell proliferation via a direct suppression of p21 expression in colorectal cancer cells. Moreover, SNHG6 repressed p21 transcription through recruiting EZH2 to the p21 promoter in colorectal cancer cells. Taken together, our study demonstrates that SNHG6 promotes tumor growth via repression of p21 in colorectal cancer, which may provide a promising target for novel anticancer therapeutics.

Li Z ，Qiu R ，Qiu X ，Tian T ... -  《-》

LncRNA SNHG6 is Associated with Poor Prognosis of Gastric Cancer and Promotes Cell Proliferation and EMT through Epigenetically Silencing p27 and Sponging miR-101-3p.

Yan K ，Tian J ，Shi W ，Xia H ，Zhu Y ... -  《-》

LncRNA SNHG17 promotes gastric cancer progression by epigenetically silencing of p15 and p57.

Long noncoding RNAs (lncRNA) are attractive biomarkers and therapeutic targets because of their disease- and stage-restricted expression. Small nucleolar RNA host gene 17 (SNHG17) belongs to a large family of noncoding genes hosting small RNAs, with its expression pattern and biological function not clarified in gastric cancer (GC). Thus, we conducted this study to investigate the functional significance and the underlying mechanisms of SNHG17 in GC progression. Our results showed that SNHG17 expression was upregulated in GC tissues and cells, and its high expression was significantly correlated with increased invasion depth, lymphatic metastasis, and advanced TNM stage. The expression of plasma SNHG17 was also found upregulated in patients with GC compared with healthy controls, with a moderate accuracy for diagnosis of GC (area under the receiver operating characteristic curve = 0.748; 95% CI, 0.666-0.830). Gain- and loss-of-function of SNHG17 revealed that SNHG17 promoted GC cell proliferation, cell cycle progression, invasion, and migration and inhibited apoptosis. Mechanistic investigations showed that SNHG17 was associated with polycomb repressive complex 2 and that this association was required for epigenetic repression of cyclin-dependent protein kinase inhibitors, including p15 and p57, thus contributing to the regulation of GC cell cycle and proliferation. Furthermore, rescue experiments indicated that SNHG17 functioned as an oncogene via activating enhancer of zeste homolog 2 in GC cells. Our study provides a new perspective for SNHG17 acting as a noncoding oncogene in GC tumorigenesis, and it may serve as a novel early diagnostic marker and potential target for the treatment of GC.

Zhang G ，Xu Y ，Wang S ，Gong Z ，Zou C ，Zhang H ，Ma G ，Zhang W ，Jiang P ... -  《-》

linc01088 promotes cell proliferation by scaffolding EZH2 and repressing p21 in human non-small cell lung cancer.

Non-small cell lung cancer (NSCLC), characterized by extensive metastasis and poor prognosis, is the most common type of lung cancer. Dysregulation of certain lncRNAs is known to be linked to the tumorigenesis of NSCLC. However, the specific roles in NSCLC for many other lncRNAs, such as linc01088, remain largely unknown. The expression patterns of linc01088, p21 and EZH2 were examined both in NSCLC tissues and cell lines using RT-qPCR assay. CCK-8, colony formation, immunofluorescence staining, and flow cytometry assays were employed to evaluate the effects of linc01088 on NSCLC cell proliferation properties. RNA immunoprecipitation (RIP) assay was performed to determine the direct binding relationship between linc01088 and zeste homolog 2 (EZH2). Western blot and RT-qPCR analysis were performed to assess p21 level within knockdown of either linc01088 or EZH2. Nude mouse subcutaneous NSCLC models were constructed for further validating the effects and mechanisms of linc01088 in vivo. linc01088 and EZH2 were highly expressed both in NSCLC tissues and cell lines. Knockdown of linc01088 suppressed the proliferation of NSCLC cells, and prolonged the G1 phase while shortened S and G2-M phases. RIP assay revealed the direct binding relationship between linc01088 and EZH2. Knockdown of either linc01088 or EZH2 induced up-regulation of p21 expression, which subsequently inhibited the tumor growth. We demonstrated that linc01088 could promote cell proliferation via binding with EZH2 to repress p21, which aggravates the tumorigenesis of NSCLC. Therefore, linc01088 might be a potential oncogene and target for novel anti-tumor therapies.

Liu JQ ，Feng YH ，Zeng S ，Zhong MZ ... -  《-》