Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Medical Center, Columbus, OH 43210, USA.
Oncogene. 2012 Sep 6;31(36):4045-53. doi: 10.1038/onc.2011.565. Epub 2011 Dec 12.
Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide with about 600 000 new cases diagnosed each year. Understanding the molecular pathways that lead to HNSCC is crucial to identify new targets for anti-cancer drug development. Protein kinase Cɛ (PKCɛ) is elevated in HNSCC and regulates the activation of Akt, Stat3 and Rho GTPases. To date, the molecular mechanism of PKCɛ dysregulation in HNSCC remains to be elucidated. In silico analysis identified three putative microRNA-107 (miR-107) binding sites in the 3'-untranslated region (UTR) of PKCɛ. An inverse relationship was revealed between miR-107 and PKCɛ in HNSCC cell lines. Delivery of miR-107 reduced PKCɛ levels in SCC15, SCC25 and CAL27, three HNSCC cell lines with high PKCɛ and low miR-107. The activity of a luciferase reporter construct containing the 3'-UTR of PKCɛ was downregulated by miR-107 and mutations in the three cognate miR-107 binding sites completely ablated the regulation by miR-107. Treatment with miR-107 significantly blocked cell proliferation, DNA replication, colony formation and invasion in SCC25 and CAL27 cells. Ectopic expression of miR-resistant PKCɛ was sufficient to partially rescue the loss-of-function phenotype in miR-107-overexpressing SCC25 cells. Tumor growth in nude mice was retarded by 93±7% in CAL27/miR-107 cells compared with CAL27/miR-control cells. Last, human primary HNSCC tumors with elevated PKCɛ had reduced miR-107 expression. Our results demonstrate that PKCɛ is directly regulated by miR-107 and, moreover, suggest that miR-107 may be a potential anti-cancer therapeutic for HNSCC.
头颈部鳞状细胞癌（HNSCC）是全球第六大常见癌症，每年约有 60 万新发病例。了解导致 HNSCC 的分子途径对于确定抗癌药物开发的新靶点至关重要。蛋白激酶 Cɛ（PKCɛ）在 HNSCC 中升高，并调节 Akt、Stat3 和 Rho GTPases 的激活。迄今为止，PKCɛ 在 HNSCC 中的失调的分子机制仍有待阐明。计算机分析在 PKCɛ 的 3'非翻译区（UTR）中鉴定出三个推定的 microRNA-107（miR-107）结合位点。在 HNSCC 细胞系中发现 miR-107 与 PKCɛ 之间呈负相关关系。miR-107 的递送降低了 SCC15、SCC25 和 CAL27 三种具有高 PKCɛ 和低 miR-107 的 HNSCC 细胞系中的 PKCɛ 水平。包含 PKCɛ 3'UTR 的荧光素酶报告基因构建体的活性被 miR-107 下调，并且三个同源 miR-107 结合位点的突变完全消除了 miR-107 的调节。miR-107 的治疗显着阻断了 SCC25 和 CAL27 细胞中的细胞增殖、DNA 复制、集落形成和侵袭。miR-107 过表达 SCC25 细胞中 miR-Resistant PKCɛ 的异位表达足以部分挽救失活功能表型。与 CAL27/miR-对照细胞相比，CAL27/miR-107 细胞中的裸鼠肿瘤生长延迟了 93±7%。最后，具有升高的 PKCɛ 的人类原发性 HNSCC 肿瘤表达降低了 miR-107。我们的结果表明 PKCɛ 受 miR-107 的直接调节，此外，提示 miR-107 可能是 HNSCC 的潜在抗癌治疗方法。
