RNA结合蛋白
细胞质
基因敲除
癌症研究
生物
核仁素
分子生物学
核糖核酸
核糖体生物发生
细胞生物学
PI3K/AKT/mTOR通路
化学
核仁
基因
核糖体
信号转导
生物化学
作者
Xiangbing Meng,Danlin Zhu,Xinjun Wang,Shujie Yang,Yuping Zhang,Zhi Xiong,Kimberly K. Leslie
出处
期刊:Cancer Research
[American Association for Cancer Research]
日期:2012-04-01
卷期号:72 (8_Supplement): 3053-3053
标识
DOI:10.1158/1538-7445.am2012-3053
摘要
Abstract Overexpression of metadherin (MTDH/AEG-1) has been documented in many solid tumors and is implicated in metastasis and chemoresistance. MTDH has been detected at the plasma membrane as well as in the cytoplasm and nucleus, and the function of MTDH in these locales remains under investigation. In the nucleus, MTDH acts as a transcription co-factor to induce expression of chemoresistance-associated genes. However, MTDH is predominantly cytoplasmic in solid tumors, and this localization has been shown to correlate with poor prognosis. In this study, we used endometrial cancer cells as a model system to define a new role for MTDH in the cytoplasm. First, MTDH was primarily localized to the cytoplasm in endometrial cancer cells, and the N-terminal region of MTDH was required to maintain cytoplasmic localization. Depletion of cytoplasmic MTDH in endometrial cancer cells restored chemosensitivity to various DNA damaging agents including mitomycin C (MMC) and doxorubicin. Next, we identified novel binding partners for cytoplasmic MTDH, including ribosome protein RPL4, ribosome biogenesis-related protein NPM1, and a component of the RNA induced silencing complex SND1. Association of MTDH with these cytoplasmic proteins was disrupted by nuclease treatment, demonstrating that nucleic acid is required for the interaction of cytoplasmic MTDH with these RNA metabolism and processing proteins. Furthermore, RNA binding protein-chromatin IP (RIP-chIP) analysis demonstrated that MTDH interacted with multiple mRNAs, and treatment with the PI3K and mTOR dual inhibitor BEZ235 altered the pattern of mRNAs that associate with MTDH. Knockdown of MTDH promoted an increase in protein levels of some MTDH-associated mRNAs. Finally, increased stress granule formation was observed in MTDH knockdown cells in response to heat shock, suggesting that one mechanism by which MTDH promotes chemoresistance is prevention of stress granule formation. Taken together, our data identify MTDH as an active RNA binding protein in the cytoplasm of cancer cells. Our findings suggest that the RNA binding properties of cytoplasmic MTDH serve to regulate genes involved in the drug resistance and metastasis of tumors and highlight MTDH as an ideal target for future drug development. Acknowledgements: This work was supported by NIH Grant R01CA99908 to K.K.L., and in part by the Department of Obstetrics and Gynecology Research Development Fund, the Institutional Research Grant Number IRG-77-004-31 from the American Cancer Society to XM. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3053. doi:1538-7445.AM2012-3053
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