Expression and mechanism of long non-coding RNA HCG22 in oral squamous cell carcinoma.

OBJECTIVES: To investigate the expression and mechanism of the long non-coding RNA (lncRNA) HCG22 in oral squamous cell carcinoma (OSCC). METHODS: HCG22 levels were detected in the OSCC and adjacent tissues, OSCC cells, and normal oral keratinocytes. HCG22 expression in SCC-25 and HSC-3 cells was upregulated by transfection of the overexpressing plasmi dvector. Methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, and Transwell assay were employed to detect changes in cell proliferation, apoptosis, migration, and invasion ability, while Western blotting was used to detect the expression of epithelial-mesenchymal transformation-related proteins. The expression level of miR-650 in the cells was detected by real-time quantitative polymerase chain reaction (RT-qPCR), and dual-luciferase reporter gene assay was applied to assess the targeting relationship between HCG22 and miR-650. RESULTS: Compared with that in adjacent tissues, the expression of HCG22 significantly decreased in OSCC tissues (P<0.05). Moreover, the prognostic survival of patients in the low-HCG22 expression group was significantly lower than that in the high-expression group (P<0.05). Compared with that in HOK cells, the expression of HCG22 was significantly lower in SCC-25, HN13, HSC-3, and CAL-27 cells (P<0.05). Upregulation of HCG22 expression could inhibit the proliferation, migration, invasion, and apoptosis of SCC-25 and HSC-3 cells, upregulatethe expression of E-cadherin, and downregulate the expression of N-cadherin and vimentin (P<0.05). miR-650 mimics could reduce the luciferase activity of HCG22 wild-type plasmid cells (P<0.05), and the expression of miR-650 in SCC-25 and HSC-3 cells decreased after upregulation of HCG22 expression (P<0.05). CONCLUSIONS: HCG22 is expressed at low levels in OSCC. Upregulation of the expression of this lncRNA can inhibit the proliferation, migration, invasion, and epithelial-mesenchymal transition of OSCC cells. The mechanism of action of HCG22 may be related to its targeted regulation of miR-650.

Assessment of multiple pathways involved in the inhibitory effect of HCG22 on oral squamous cell carcinoma progression.

LncRNAs have been proposed to be associated with the tumorigenesis and progression of oral squamous cell carcinoma (OSCC). LncRNA HLA complex group 22 (HCG22) was reported to be lowly expressed and associated with poor prognosis in head and neck squamous cell carcinoma (HNSCC). However, the biological role and related mechanism of HCG22 in OSCC have not been characterized. HCG22 expression in OSCC cells was detected by qRT-PCR. Cell proliferation, invasion, and apoptosis were evaluated by Bromodeoxyuridine (BrdU) proliferation assay, Transwell invasion assay, and flow cytometry analysis, respectively. The protein levels of proliferating cell nuclear antigen (PCNA), E-cadherin, Vimentin, Bcl-2, Bax, protein kinase B (Akt), phosphorylated Akt (p-Akt), mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), and ß-catenin were detected by western blot. Cell growth evaluation was performed using in vitro colony formation assay and in vivo tumor xenograft assay. We found that HCG22 was weakly expressed in OSCC cells. HCG22 overexpression inhibited cell proliferation and invasion and induced apoptosis in OSCC cells. The levels of PCNA, Vimentin, and Bcl-2 were decreased and E-cadherin and Bax expression was elevated in OSCC cells after HCG22 overexpression. Additionally, HCG22 overexpression inhibited the Akt, mTOR and Wnt/ß-catenin pathways. Activation of Akt, mTOR, and Wnt/ß-catenin pathways attenuated the anti-tumor property of HCG22 in OSCC cells. Furthermore, HCG22 overexpression inhibited the growth of OSCC cells in vitro and in vivo. In conclusion, HCG22 exerted anti-tumor property in OSCC by inhibiting the Akt, mTOR, and Wnt/ß-catenin pathways.

Construction and analysis of a lncRNA-miRNA-mRNA network based on competitive endogenous RNA reveal functional lncRNAs in oral cancer.

BACKGROUND: A growing evidence suggests that long non-coding RNAs (lncRNAs) can function as a microRNA (miRNA) sponge in various diseases including oral cancer. However, the pathophysiological function of lncRNAs remains unclear. METHODS: Based on the competitive endogenous RNA (ceRNA) theory, we constructed a lncRNA-miRNA-mRNA network in oral cancer with the human expression profiles GSE74530 from the Gene Expression Omnibus (GEO) database. We used topological analysis to determine the hub lncRNAs in the regulatory ceRNA network. Then, function enrichment analysis was performed using the clusterProfiler R package. Clinical information was downloaded from The Cancer Genome Atlas (TCGA) database and survival analysis was performed with Kaplan-Meier analysis. RESULTS: A total of 238 potential co-dysregulated competing triples were obtained in the lncRNA-associated ceRNA network in oral cancer, which consisted of 10 lncRNA nodes, 41 miRNA nodes and 122 mRNA nodes. Additionally, we found lncRNA HCG22 exhibiting superior potential as a diagnostic and prognostic marker of oral cancer. CONCLUSIONS: Our findings provide novel insights to understand the ceRNA regulation in oral cancer and identify a novel lncRNA as a potential molecular biomarker.

Long noncoding RNA HCG22 suppresses proliferation and metastasis of bladder cancer cells by regulation of PTBP1.

Multifarious biological functions of long noncoding RNAs (lncRNAs) have been reported in various cancers including bladder cancer (BCa). This study aims to determine the biological role of a certain lncRNA in BCa. Consistent with the data of The Cancer Genome Atlas database, it was validated that lncRNA HLA complex group 22 (HCG22) was weakly expressed in BCa samples and lowly expressed HCG22 was closely correlated with low overall survival of the BCa patient. To verify the role of HCG22 in BCa progression, functional experiments were carried out in two representative BCa cells (J82 and T24) and the negative effects of HCG22 expression on the cell proliferation, migration, and epithelial-mesenchymal transition were identified. Mechanistically, polypyrimidine tract-binding protein 1 (PTBP1), which was highly expressed in BCa tissues and cell lines, was negatively regulated by HCG22 and the PTBP1-mediated Warburg effect was also obstructed by HCG22. Furthermore, HCG22 modulated the expression of PTBP1 through destabilizing human antigen R (HuR). And functional rescue assays confirmed that HCG22 functioned in bladder cancer through downregulating PTBP1. In conclusion, the present study revealed that HCG22 inhibited BCa progression via the HuR/PTBP1 axis, opening new prospects for potent therapeutic regimens for BCa patients.

Comprehensive bioinformatics analysis identifies lncRNA HCG22 as a migration inhibitor in esophageal squamous cell carcinoma.

Esophageal cancer is one of the most lethal malignancies worldwide, and esophageal squamous cell carcinoma (ESCC) is the dominant histological type. However, the long noncoding RNA (lncRNA) alterations in ESCC have not been elucidated to date. In this study, reliable databases from Gene Expression Omnibus (GEO), which analyzed lncRNA expression in ESCC tumor tissues and adjacent normal tissues were searched, and common differentially expressed lncRNAs and genes were analyzed. Next, cis- trans analysis was performed to predict the underlying relationships between altered lncRNAs and mRNAs, and the lncRNA-mRNA regulatory network was established. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of altered lncRNA-related genes were performed. The promising lncRNA HCG22 was validated by quantitative polymerase chain reaction (qPCR), and clinicopathological data were collected to identify the relationship between lncRNA HCG22 expression level and clinical features. Finally, Transwell assays were performed to explore the biological functions of lncRNA HCG22 in ESCC cells. Two hundred forty-one lncRNAs and 835 mRNAs were observed to be remarkably altered between ESCC tumor tissues and adjacent normal tissues. The lncRNA-mRNA regulatory network showed the coexpression association between lncRNA HCG22 and SPINK7 and ADAMTS12. GO and KEGG analyses showed that HCG22 and ADAMTS12 had potential biological functions in the cell migration of ESCC. The downregulation of lncRNA HCG22 in ESCC tumor tissues was validated by qPCR, and the clinicopathological data showed a noticeable correlation between lncRNA HCG22 expression level and the ESCC differentiational degree and clinical TNM stage. Kaplan-Meier analysis showed that patients with ESCC having low lncRNA HCG22 expression in ESCC tissues had considerably shorter overall survival compared with patients with ESCC having high lncRNA HCG22 expression. Following Transwell assays confirmed the migratory role of lncRNA HCG22 in ESCC cells. In conclusion, lncRNA HCG22 was downregulated in ESCC tissues and can be a migration inhibitor of ESCC cells, and SPINK7 and ADAMTS12 are promising to be the regulatory targets of lncRNA HCG22.