Mounting evidence demonstrates that long noncoding RNAs (lncRNAs) have critical roles during the initiation and progression of cancers. In this study, we report that the small nucleolar RNA host gene 1 (SNHG1) is involved in colorectal cancer progression. We analyzed RNA sequencing data to explore abnormally expressed lncRNAs in colorectal cancer. The effects of SNHG1 on colorectal cancer were investigated through in vitro and in vivo assays (i.e., CCK-8 assay, colony formation assay, flow cytometry assay, EdU assay, xenograft model, immunohistochemistry, and western blot). The mechanism of SNHG1 action was explored through bioinformatics, RNA fluorescence in situ hybridization, luciferase reporter assay, RNA pull-down assay, chromatin immunoprecipitation assay and RNA immunoprecipitation assay. Our analysis revealed that SNHG1 was upregulated in human colorectal cancer tissues, and high SNHG1 expression was associated with reduced patient survival. We also found that high SNHG1 expression was partly induced by SP1. Moreover, SNHG1 knockdown significantly repressed colorectal cancer cells growth both in vitro and in vivo. Mechanistic investigations demonstrated that SNHG1 could directly interact with Polycomb Repressive Complex 2 (PRC2) and modulate the histone methylation of promoter of Kruppel like factor 2 (KLF2) and Cyclin dependent kinase inhibitor 2B (CDKN2B) in the nucleus. In the cytoplasm, SNHG1 acted as a sponge for miR-154-5p, reducing its ability to repress Cyclin D2 (CCND2) expression. Taken together, the results of our studies illuminate how SNHG1 formed a regulatory network to confer an oncogenic function in colorectal cancer and suggest that SNHG1 may serve as a potential target for colorectal cancer diagnosis and treatment.

Emerging studies suggest that long non-coding RNAs (lncRNAs) play crucial roles in colorectal cancer (CRC). Here, we report a lncRNA, SATB2-AS1, which is specifically expressed in colorectal tissue and is significantly reduced in CRC. We systematically elucidated its functions and possible molecular mechanisms in CRC. LncRNA expression in CRC was analyzed by RNA-sequencing and RNA microarrays. The expression level of SATB2-AS1 in tissues was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). The functional role of SATB2-AS1 in CRC was investigated by a series of in vivo and in vitro assays. RNA pull-down, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), chromatin isolation by RNA purification (ChIRP), Bisulfite Sequencing PCR (BSP) and bioinformatics analysis were utilized to explore the potential mechanisms of SATB2-AS1. SATB2-AS1 is specifically expressed in colorectal tissues and downregulated in CRC. Survival analysis indicates that decreased SATB2-AS1 expression is associated with poor survival. Functional experiments and bioinformatics analysis revealed that SATB2-AS1 inhibits CRC cell metastasis and regulates TH1-type chemokines expression and immune cell density in CRC. Mechanistically, SATB2-AS1 directly binds to WDR5 and GADD45A, cis-activating SATB2 (Special AT-rich binding protein 2) transcription via mediating histone H3 lysine 4 tri-methylation (H3K4me3) deposition and DNA demethylation of the promoter region of SATB2. This study reveals the functions of SATB2-AS1 in CRC tumorigenesis and progression, suggesting new biomarkers and therapeutic targets in CRC.

Background: Abnormal expression of long non-coding RNAs (lncRNAs) has been found in almost all human tumors, providing numerous potential diagnostic biomarkers, prognostic biomarkers, and therapeutic targets. Methods: We analyzed RNA sequencing data to explore abnormally expressed lncRNAs in colorectal cancer (CRC). The functions of small nucleolar RNA host gene 6 (SNHG6) were investigated through in vitro and in vivo assays (CCK-8 assay, colony formation assay, flow cytometry assay, EdU assay, wound healing assay, transwell assay, and xenograft model). The mechanism of action of SNHG6 was explored through bioinformatics, RNA fluorescence in situ hybridization, luciferase reporter assay, RNA pull-down assay, chromatin immunoprecipitation assay, and RNA immunoprecipitation assay. Results: We identified aberrantly expressed lncRNAs in CRC. We found that elevated SNHG6 expression was associated with poor prognosis and CRC progression. We also demonstrated that the high SNHG6 expression was partly due to DNA copy number gains and SP1 induction. Functional studies showed that SNHG6 promoted CRC cell growth, migration, and invasion both in vitro and in vivo. Mechanistically, we found that SNHG6 expressed predominantly in the cytoplasm. SNHG6 could interact with miR-26a, miR-26b, and miR-214 and regulate their common target EZH2. Conclusions: Our study elucidated that SNHG6 acted as an oncogene in CRC, which might serve as a novel target for CRC diagnosis and therapy.

For lung adenocarcinoma (LUAD), the competitive endogenous RNA (ceRNA) networks mediated by circular RNAs (circRNAs) have been partially constructed. However, a mass of networks still need to be thoroughly investigated to uncover novel regulatory axes in LUAD. Clinical information along with transcriptome data were obtained from open databases. The circRNA-mediated ceRNA subnetworks and a risk score were constructed through layer-by-layer screening and validating. Immune infiltration analysis was performed by CIBERSORT. Quantitative real-time PCR, immunohistochemical analysis, and dual-luciferase reporter assays confirmed the expression and relationships of hub genes. The expression of 9 circRNAs, 81 miRNAs, and 952 mRNAs significantly varied in LUAD tissues. Subsequently, 63 miRNA-mRNA interactions and 3 circRNA-miRNA interactions were employed to generate a ceRNA network. Two prognostic subnetworks mediated by hsa_circ_0072088 and hsa_circ_0049271 were obtained following hub genes screening and survival analysis. Then, a risk score consisting of MMP14 and DCN was successfully constructed and verified using a different dataset. Among the high-risk group, more deaths and poor prognosis occurred. The distribution of immune infiltrating cells varied between high- and low-risk groups, and they were correlated with both the expression of DCN and MMP14 and the risk score. The two key regulatory axes, hsa_circ_0072088/hsa-miR-532-3p/MMP14 and hsa_circ_0049271/hsa-miR-224-5p/DCN, might be involved in carcinogenesis, prognosis and immune infiltration of LUAD.