CAP70表达异常下调在肾癌发生发展和不良预后中起着重要作用，但细胞内调节其表达的分子机制尚不明确。我们初步发现：miR-15b可抑制CAP70的表达且在肾癌中异常上调，而含miR-15b响应元件的lnc-PENG可上调CAP70的表达并在肾癌中异常下调，且二者均与细胞增殖和病人预后密切相关。据此我们提出：PENG作为竞争性内源RNA(ceRNA)与CAP70竞争结合miR-15b协调调节CAP70的表达；肾癌中PENG异常下调和miR-15b异常上调引起CAP70表达异常下调，导致肾癌发生发展。本课题拟从分子、细胞、动物和临床层面系统阐明PENG和miR-15b通过ceRNA机制调节CAP70的表达进而影响肾癌恶性表型及二者作为新型肾癌诊断和预后标志物的前景。本研究结果将揭示一种细胞内调节CAP70表达及影响肾癌恶性表型的新机制，并为寻找新型肾癌诊断、预后标志物和治疗靶点提供理论依据。

CAP70 plays an important role in tumorigenesis and progression of renal cell carcinoma (RCC) and its expression level was aberrantly downregulated in RCC tissues. However, the underlying mechanism by which CAP70 expression level was downregulated remains unclear. Our preliminary work showed that miR-15b was upregulated in RCC tissues. MiR-15b can bind to 3-untranslated region (3-UTR) of CAP70 mRNA and negatively regulated the expression of CAP70. LncRNA-PENG positively regulated the expression of CAP70 by binding to miR-15b via its miRNA response elements (MREs). Both miR-15b and PENG were involved in renal cancer cell proliferation and correlated with the poor prognosis of RCC patients. Based on this, we hypothesized that PENG may act as competing endogenous RNA (ceRNA) by binding competitively to miR-15b. PENG was aberrantly downregulated in RCC tissue and dysregulated in acting as ceRNAs, leading to the downregulated CAP70 expression and the development of RCC. In this study, we aimed to identify the roles of miR-15b and PENG in the regulation of CAP70 expression, RCC occurrence, progression and prognosis by cell and nude mice experiments and clinical samples analysis. In addition, this study also aimed to elucidate whether miR-15b and PENG might be used as the diagnostic and prognostic biomarker for RCC. The results of this study will reveal a novel mechanism for the regulation of CAP70 expression level and RCC malignant phenotype, and may provide further evidences in finding diagnostic and prognostic biomarker, new drug targets for RCC.