PURPOSE Metaplastic breast carcinomas are an aggressive subtype of triple-negative breast cancer (TNBC) in which part or all of the adenocarcinoma transforms into a non-glandular component (e.g., spindled, squamous, or heterologous). We discovered that mammary-specific Ccn6/Wisp3 knockout mice develop mammary carcinomas with spindle and squamous differentiation that share upregulation of the oncofetal proteins IGF2BP2 (IMP2) and HMGA2 with human metaplastic carcinomas. Here, we investigated the functional relationship between CCN6, IGF2BP2, and HMGA2 proteins in vitro and in vivo, and their expression in human tissue samples. METHODS MMTV-cre;Ccn6fl/fl tumors and spindle TNBC cell lines were treated with recombinant CCN6 protein or vehicle. IGF2BP2 was downregulated using shRNAs in HME cells with stable CCN6 shRNA knockdown, and subjected to invasion and adhesion assays. Thirty-one human metaplastic carcinomas were arrayed in a tissue microarray (TMA) and immunostained for CCN6, IGF2BP2, and HMGA2. RESULTS CCN6 regulates IGF2BP2 and HMGA2 protein expression in MMTV-cre;Ccn6fl/fl tumors, in MDA-MB-231 and - 468, and in HME cells. CCN6 recombinant protein reduced IGF2BP2 and HMGA2 protein expression, and decreased growth of MMTV-cre;Ccn6fl/fl tumors in vivo. IGF2BP2 shRNA knockdown was sufficient to reverse the invasive abilities conferred by CCN6 knockdown in HME cells. Analyses of the TCGA Breast Cancer Cohort (n = 1238) showed that IGF2BP2 and HMGA2 are significantly upregulated in metaplastic carcinoma compared to other breast cancer subtypes. In clinical samples, low CCN6 is frequent in tumors with high IGF2BP2/HMGA2 with spindle and squamous differentiation. CONCLUSIONS These data shed light into the pathogenesis of metaplastic carcinoma and demonstrate a novel CCN6/IGF2BP2/HMGA2 oncogenic pathway with biomarker and therapeutic implications.

中文翻译：

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CCN6调节乳腺增生癌中的IGF2BP2和HMGA2信号传导。

目的转基因乳腺癌是三阴性乳腺癌（TNBC）的一种侵略性亚型，其中部分或全部腺癌转化为非腺性成分（例如纺锤状，鳞状或异源性）。我们发现，乳腺特异性Ccn6 / Wisp3基因敲除小鼠会发展出具有梭形和鳞状分化的乳癌，与人化生性癌共享癌胚蛋白IGF2BP2（IMP2）和HMGA2的上调。在这里，我们调查了CCN6，IGF2BP2和HMGA2蛋白在体内和体外之间的功能关系，以及它们在人体组织样品中的表达。方法用重组CCN6蛋白或媒介物处理MMTV-cre; Ccn6fl / fl肿瘤和梭形TNBC细胞系。在具有稳定CCN6 shRNA敲低功能的HME细胞中，使用shRNA上调了IGF2BP2，并进行入侵和粘附测定。将三十一种人化生性癌症排列在组织微阵列（TMA）中，并对CCN6，IGF2BP2和HMGA2进行免疫染色。结果CCN6调节MMTV-cre; Ccn6fl / fl肿瘤，MDA-MB-231和-468以及HME细胞中的IGF2BP2和HMGA2蛋白表达。CCN6重组蛋白在体内降低了IGF2BP2和HMGA2蛋白的表达，并降低了MMTV-cre; Ccn6fl / fl肿瘤的生长。IGF2BP2 shRNA敲低足以逆转CME6敲低HME细胞所赋予的侵袭能力。TCGA乳腺癌队列（n = 1238）的分析表明，与其他乳腺癌亚型相比，化生癌中IGF2BP2和HMGA2明显上调。在临床样品中，低CCN6在高IGF2BP2 / HMGA2伴梭形和鳞状分化的肿瘤中很常见。