PurposeStudies have found that long noncoding RNA HEIH (lncRNA-HEIH) is upregulated and facilitates hepatocellular carcinoma tumor growth. However, its clinical significances, roles, and action mechanism in colorectal cancer (CRC) remains unidentified.Materials and MethodslncRNA-HEIH expression in CRC tissues and cell lines was measured by quantitative real-time polymerase chain reaction. Cell CountingKit-8, ethynyl deoxyuridine incorporation assay, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and nude mice xenografts assays were performed to investigate the roles of lncRNA-HEIH. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and luciferase reporter assays were performed to investigate the action mechanisms of lncRNA-HEIH.ResultsIn this study, we found that lncRNA-HEIH is significantly increased in CRC tissues and cell lines. lncRNA-HEIH expression is positively associated with tumor size, invasion depth, and poor prognosis of CRC patients. Enhanced expression of lncRNA-HEIH promotes CRC cell proliferation and decreases apoptosis in vitro, and promotes CRC tumor growth in vivo. Whereas knockdown of lncRNA-HEIH inhibits CRC cell proliferation and induces apoptosis in vitro, and suppresses CRC tumor growth in vivo. Mechanistically, lncRNA-HEIH physically binds to miR-939. The interaction between lncRNA-HEIH and miR-939 damages the binding between miR-939 and nuclear factor κB (NF-κB), increases the binding of NF-κB to Bcl-xL promoter, and promotes the transcription and expression of Bcl-xL. Moreover, Bcl-xL expression is positively associatedwith lncRNA-HEIH in CRC tissues. Blocking the interaction between lncRNA-HEIH and miR-939 abolishes the effects of lncRNA-HEIH on CRC tumorigenesis.ConclusionThis study demonstrated that lncRNA-HEIH promotes CRC tumorigenesis through counteracting miR-939‒mediated transcriptional repression of Bcl-xL, and suggested that lncRNA-HEIH may serve as a prognostic biomarker and therapeutic target for CRC.
Connective tissue growth factor (CTGF) has different roles in different types of cancer. However, the involvement and molecular basis of CTGF in tumor progression and prognosis of human nasopharyngeal carcinoma (NPC) have almost never been reported. In this study, we observed that downregulated CTGF expression was significantly associated with NPC progression and poor prognosis. Knockdown of CTGF markedly elevated the ability of cell proliferation in vivo and in vitro. Subsequently, we discovered that the reduction of CTGF increased the expression of miR-18b, an oncomir-promoting cell proliferation. Further, we discovered that attenuated CTGF-mediated upregulation of miR-18b was dependent on the increased binding of transcription factors Jun proto-oncogene (C-Jun) and v-Myc myelocytomatosis viral oncogene homolog (C-Myc) to miR-18b promoter region via phosphoinositide 3-kinase (PI3K)/AKT pathway. Finally, we further found that miR-18b directly suppressed the expression of CTGF in NPC. In clinical fresh specimens, miR-18b was widely overexpressed and inversely correlated with CTGF expression in NPC. Our studies are the first to demonstrate that reduced CTGF as an unfavorable prognosis factor mediates the activation of miR-18b, an oncomir directly suppresses CTGF expression, by PI3K/AKT/C-Jun and C-Myc and promotes cell growth of NPC.
Abstract. Metastasis is the primary cause of mortality in colorectal cancer (CRC), the mechanism of which remains unclear. In the present study, by detecting mRNA expression using a reverse transcription-quantitative polymerase chain reaction (qPCR), it was revealed that sterol regulatory element-binding protein 1 (SREBP1) is highly expressed in CRC. Using a cell wound healing assay and a cell invasion assay, a novel metastasis-promoting role for SREBP1 in CRC was identified. Furthermore, snail family transcriptional repressor 1 (SNAIL) was identified as a key downstream effector of SREBP1 in CRC by the use of small interfering RNA against SNAIL. Additionally, using co-immunoprecipitation and chromatin immunoprecipitation-qPCR assays, it was demonstrated that SREBP1 interacts with c-MYC to enhance the binding of c-MYC to the promoter of the mesenchymal gene, SNAIL, thereby increasing SNAIL expression and accelerating epithelial-mesenchymal transition. These results indicated a novel role for SREBP1 and provide insight into the regulatory mechanisms of the c-Myc oncogene in CRC, which may function as a potential therapeutic target for CRC treatment.
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