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Hypoxia-sensitive long noncoding RNA CASC15 promotes lung tumorigenesis by regulating the SOX4/?-catenin axis.

ABSTRACT:

Background

Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are involved in the hypoxia-related cancer process and play pivotal roles in enabling malignant cells to survive under hypoxic stress. However, the molecular crosstalk between lncRNAs and hypoxia signaling cascades in non-small cell lung cancer (NSCLC) remains largely elusive.

Methods

Firstly, we identified differentially expressed lncRNA cancer susceptibility candidate 15 (CASC15) as associated with NSCLC based on bioinformatic data. The clinical significance of CASC15 in lung cancer was investigated by Kaplan-Meier survival analysis. Then, we modulated CASC15 expression in NSCLC cell lines by RNAi. CCK-8 and transwell assays were carried out to examine the effects of CASC15 on proliferation and migration of NSCLC cells. Upstream activator and downstream targets of CASC15 were validated by luciferase reporter assay, qRT-PCR, Western blotting, and chromatin immunoprecipitation (ChIP). Lastly, RNA in situ hybridization (RNA-ISH) and immunohistochemistry (IHC) were performed to confirm the genetic relationships between CASC15 and related genes in clinical samples.

Results

CASC15 was highly expressed in NSCLC tissues and closely associated with poor prognosis. Loss-of-function analysis demonstrated that CASC15 was essential for NSCLC cell migration and growth. Mechanistic study revealed that CASC15 was transcriptionally activated by hypoxia signaling in NSCLC cells. Further analysis showed that hypoxia-induced CASC15 transactivation was mainly dependent on hypoxia-inducible factor 1? (HIF-1?) and hypoxia response elements (HREs) located in CASC15 promoter. CASC15 promotes the expression of its chromosomally nearby gene, SOX4. Then SOX4 functions to stabilize ?-catenin protein, thereby enhancing the proliferation and migration of NSCLC cells. HIF-1?/CASC15/SOX4/?-catenin pathway was activated in a substantial subset of NSCLC patients.

Conclusions

HIF-1?/CASC15/SOX4/?-catenin axis plays an essential role in the development and progression of NSCLC. The present work provides new evidence that lncRNA CASC15 holds great promise to be used as novel biomarkers for NSCLC. Blocking the HIF-1?/CASC15/SOX4/?-catenin axis can serve as a potential therapeutic strategy for treating NSCLC.

SUBMITTER: Sun J

PROVIDER: S-EPMC7789733 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

Hypoxia-sensitive long noncoding RNA CASC15 promotes lung tumorigenesis by regulating the SOX4/β-catenin axis.

Sun Jianyong J Xiong Yanlu Y Jiang Kuo K Xin Bo B Jiang Tongtong T Wei Renji R Zou Yuankang Y Tan Hong H Jiang Tao T Yang Angang A Jia Lintao L Wang Lei L

Journal of experimental & clinical cancer research : CR 20210106 1

<h4>Background</h4>Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) are involved in the hypoxia-related cancer process and play pivotal roles in enabling malignant cells to survive under hypoxic stress. However, the molecular crosstalk between lncRNAs and hypoxia signaling cascades in non-small cell lung cancer (NSCLC) remains largely elusive.<h4>Methods</h4>Firstly, we identified differentially expressed lncRNA cancer susceptibility candidate 15 (CASC15) as associated ...[more]

PMID: 33407675

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Project description:Osteosarcoma (OS) is a rare type of tumor and mostly occurs in children and adolescents. Approximately 10‑25% of patients with OS have lung metastases, and lung damage caused by lung metastasis is the main cause of mortality. Therefore, studying the growth and metastasis of OS is key in reducing OS mortality and improving prognosis. The expression of long non‑coding RNA (lncRNA) cancer susceptibility 15 (CASC15) in OS patients or OS cell lines were quantified by reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The expression of vimentin, E‑cadherin, N‑cadherin, and cyclin D were detected by RT‑qPCR and western blotting. Mice were injected with OS cell lines via the tail vein to observe tumor formation in the lung. CCK‑8 and EdU assays were utilized to evaluate cell proliferation. Both Ttranswell assay and cell scratch test detected cell migration. The results revealed that lncRNA‑CASC15 was highly expressed in clinical samples and OS cells. In vitro verification experiments revealed that CASC15 promoted the growth of OS cells. Rescue experiments demonstrated that CASC15 affected the cell cycle by activating the Wnt/β‑catenin pathway, thereby promoting cell proliferation. Furthermore, the transfection dose test indicated that lentiviruses expressing various doses of CASC15‑overexpression (oe‑CASC15) altered the proliferation and migration status of OS cells. CASC15 promoted OS cell metastasis both in vivo and in vitro. The overexpression of CASC15 revealed that the occurrence of metastasis was also related to the Wnt/β‑catenin pathway. The western blotting results revealed that CASC15 could lead to β‑catenin entering the nucleus via the Wnt pathway to promote the epithelial‑mesenchymal transition (EMT) of OS cells. To sum up, CASC15 promoted the proliferation of OS cells in vitro and the growth of OS xenograft tumors in vivo. Moreover, CASC15 promoted the entry of β‑catenin into the nucleus, thus activating the Wnt pathway and subsequently promoting the EMT of OS cells.