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Background Long non-coding RNAs (lncRNAs) function as a class of significant mediators in prostate cancer (PCa), and this study mainly discussed the molecular mechanism of lncRNA growth arrest-specific 5 (GAS5) in PCa progression and radiosensitivity. Materials and methods GAS5 and microRNA-320a (miR-320a) levels were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and migration were severally examined through 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) and transwell assays. PCa cells were treated with X-ray irradiation. Cell survival and apoptosis rate were assayed using colony formation assay and flow cytometry, respectively. The apoptosis-related protein and Rab GTPase 21 (RAB21) protein levels were measured by Western blot. The relation between miR-320a and GAS5 or RAB21 was assessed via the dual-luciferase reporter assay. The effect of GAS5 on radiosensitivity of PCa in vivo was evaluated by xenotransplantation assay. Results GAS5 was down-regulated in PCa tissues and cells. GAS5 overexpression suppressed cell viability and migration while facilitated radiosensitivity of PCa cells. GAS5 was a molecular sponge of miR-320a. The effects of GAS5 up-regulation on PCa cells were accomplished by sponging miR-320a. MiR-320a targeted RAB21 and GAS5 up-regulated RAB21 expression via targeting miR-320a. RAB21 knockdown reversed the effects of miR-320a inhibition on PCa cells. GAS5 promoted the radiosensitivity of PCa by the miR-320a/RAB21 axis in vivo. Conclusion Collectively, GAS5 restrained tumor development and expedited the radiosensitivity in PCa by the miR-320a/RAB21 axis, which provided a molecular regulatory mechanism of GAS5/miR-320a/RAB21 in PCa development and radioresistance.

e16510 Background: Increasing evidence has revealed that long non-coding RNAs (lncRNAs) play a crucial role in cancer immunity. However, the comprehensive landscape of immune infiltration-associated lncRNAs and their potential roles in the prognosis and diagnosis of kidney renal clear cell carcinoma (KIRC) remains largely unexplored. Methods: The transcriptomics data, expression profiles, and clinical information of KIRC patients were obtained from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database. Novel lncRNAs were identified by a custom pipeline. The infiltration of immune cells was calculated by ssGSEA. K-means consensus method was used to cluster KIRC samples in different groups. Immune-related lncRNAs were obtained by differential expression analysis based on these groups. Univariate Cox regression, LASSO regression, and multivariate Cox regression analysis were performed on GEO datasets to construct an immune-related lncRNAs signature for predicting the prognosis of KIRC. And then, validated the prognostic signature in TCGA data. Results: Based on 261 samples from KIRC patients, tens of thousands of novel lncRNA genes were identified. KIRC samples were clustered into three immune clusters based on the infiltration of immune cells. Based on these groups, 241 immune-related lncRNAs were obtained. Moreover, a large part of immune-related lncRNAs could be detected in urinary samples of KIRC. Through a series of analyses, three immune-related lncRNAs were identified as a prognostic signature for KIRC. KIRC patients in the high-risk group had a shorter OS than those in the low-risk group both in the training set (P < 0.001) and TCGA data (P < 0.001), respectively. The AUC was 0.9 in the training set. Univariate and multivariate Cox regression analysis confirmed that the immune-related lncRNAs signature could be an independent prognostic factor both in the training set and TCGA data. Conclusions: All these findings provide a more comprehensive lncRNAs catalog for investigating the lncRNAs and provide a novel approach for the effective prediction of clinical outcomes in KIRC.