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Rab27A mediated by NF-?B promotes the stemness of colon cancer cells via up-regulation of cytokine secretion.

ABSTRACT: Recent evidences have unveiled critical roles of cancer stem cells (CSCs) in tumorigenicity, but how interactions between CSC and tumor environments help maintain CSC initiation remains obscure. The small GTPases Rab27A regulates autocrine and paracrine cytokines by monitoring exocytosis of extracellular vesicles, and is reported to promote certain tumor progression. We observe that overexpression of Rab27A increased sphere formation efficiency (SFE) by increasing the proportion of CD44+ and PKH26high cells in HT29 cell lines, and accelerating the growth of colosphere with higher percentage of cells at S phase. Mechanism study revealed that the supernatant derived from HT29 sphere after Rab27A overexpression was able to expand sphere numbers with elevated secretion of VEGF and TGF-?. In tumor implanting nude mice model, tumor initiation rates and tumor sizes were enhanced by Rab27A with obvious angiogenesis. As a contrast, knocking down Rab27A impaired the above effects. More importantly, the correlation between higher p65 level and Rab27A in colon sphere was detected, p65 was sufficient to induce up-regulation of Rab27A and a functional NF-?B binding site in the Rab27A promoter was demonstrated. Altogether, our findings reveal a unique mechanism that tumor environment related NF-?B signaling promotes various colon cancer stem cells (cCSCs) properties via an amplified paracrine mechanism regulated by higher Rab27A level.

SUBMITTER: Feng F

PROVIDER: S-EPMC5325368 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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Rab27A mediated by NF-κB promotes the stemness of colon cancer cells via up-regulation of cytokine secretion.

Feng Feixue F Jiang Yinghao Y Lu Huanyu H Lu Xiaozhao X Wang Shan S Wang Lifeng L Wei Mengying M Lu Wei W Du Zhichao Z Ye Zichen Z Yang Guodong G Yuan Fang F Ma Yanxia Y Lei Xiaoying X Lu Zifan Z

Oncotarget 20160901 39

Recent evidences have unveiled critical roles of cancer stem cells (CSCs) in tumorigenicity, but how interactions between CSC and tumor environments help maintain CSC initiation remains obscure. The small GTPases Rab27A regulates autocrine and paracrine cytokines by monitoring exocytosis of extracellular vesicles, and is reported to promote certain tumor progression. We observe that overexpression of Rab27A increased sphere formation efficiency (SFE) by increasing the proportion of CD44+ and PKH ...[more]

PMID: 27556511

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Project description:BackgroundCheckpoint blockade therapies targeting programmed death ligand 1 (PD-L1) and its receptor programmed cell death 1 promote T cell-mediated immune surveillance against tumors and have been associated with significant clinical benefit in cancer patients. The long-stranded non-coding RNA HOTAIR is highly expressed and associated with metastasis in a variety of cancer types and promotes tumor metastasis at least in part through association with the PRC2 complex that induces redirection to hundreds of genes involved in tumor metastasis. Here, we report that HOTAIR is an activator lncRNA of the NF-κB pathway and demonstrate that its apparent upregulation promotes inflammatory signaling and immune escape in glioma cells.MethodsBioinformatics analysis was used to elucidate the relationship between HOTAIR and NF-κB pathway in HOTAIR knockdown glioma cells. At the cytological level, protein hybridization and immunofluorescence were used to detect the response of proteins in the NF-κB signaling pathway to HOTAIR regulation. ChIP and ChIRP experiments identified HOTAIR target genes. Animal experiments verified alterations in inflammation and immune escape following HOTAIR knockdown and activity inhibition.ResultsHOTAIR activated the expression of proteins involved in NF-κB, TNFα, MAPK and other inflammatory signaling pathways. In addition, HOTAIR induced various proteins containing protein kinase structural domains and promoted the enrichment of proteins and complexes of important inflammatory signaling pathways, such as the TNFα/NF-κB signaling protein complex, the IκB kinase complex, and the IKKA-IKKB complex. In addition, HOTAIR aberrantly activated biological processes involved in glioma immune responses, T-cell co-stimulation and transcription initiation by RNA polymerase II. HOTAIR facilitated the induction of IκBα phosphorylation by suppressing the expression of the NF-κB upstream protein UBXN1, promoting NF-κB phosphorylation and nuclear translocation. In vivo, reduction of HOTAIR decreased PD-L1 protein expression, indicating that cells are more likely to be targeted by immune T cells.ConclusionIn conclusion, our results provide convincing evidence that lncRNA HOTAIR drives aberrant gene transcription and immune escape from tumor cells through the NF-κB pathway.

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Rab27A mediated by NF-?B promotes the stemness of colon cancer cells via up-regulation of cytokine secretion.

Publications

Rab27A mediated by NF-κB promotes the stemness of colon cancer cells via up-regulation of cytokine secretion.

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