Johnson Jacob P S, Kumar Prashant, Koulnis Miroslav, Patel Milan, Simin Karl
Department of Cancer Biology, University of Massachusetts Medical School, Worcester, MA, U.S.A.
Institute of Molecular and Cell Biology, ASTAR, Singapore.
Cancer Genomics Proteomics. 2014 May-Jun;11(3):115-26.
We previously developed a mouse model of breast cancer that mimics human triple-negative breast cancer (TNBC) by inactivating the Retinoblastoma (Rb), Transformation related protein 53 (p53), and Breast cancer 1 (Brca1) pathways in the mammary gland. Despite inactivation of all three tumor suppressors throughout the epithelium, low tumor multiplicity indicated that malignant carcinoma progression requires additional oncogenic stimuli.
In order to identify collaborating genetic events, we performed integrated analysis of 18 tumors (eight tumors with inactivation of pRbf/Brca1/p53 and ten tumors with inactivation of pRbf/p53) using comparative genomic hybridization and global gene expression. We then conducted flow cytometric analysis, immunostaining, tumorsphere, and cell viability assays.
Copy number aberrations were correlated with the transcript levels of 7.55% of genes spanned by the altered genomic regions. Recurrent genomic losses spanning large regions of chromosomes 4 and 10 included several cell death genes. Among the amplified genes were well-known drivers of tumorigenesis including Wingless-related MMTV integration site 2 (Wnt2), as well as potentially novel driver mutations including the Late cornified envelope (LCE) gene family. These tumors have a stem/luminal progenitor phenotype and active β-catenin signaling. Tumorsphere formation and cell survival are suppressed by Wnt pathway inhibitors.
Our novel mouse model mimics human TNBC and provides a platform to triage the pathways that underlie malignant tumor progression.
我们之前构建了一种乳腺癌小鼠模型，通过使乳腺中的视网膜母细胞瘤（Rb）、转化相关蛋白53（p53）和乳腺癌1（Brca1）通路失活来模拟人类三阴性乳腺癌（TNBC）。尽管上皮细胞中的所有三种肿瘤抑制因子均失活，但低肿瘤多样性表明恶性癌进展需要额外的致癌刺激。
为了识别协同发生的基因事件，我们使用比较基因组杂交和全基因表达对18个肿瘤（8个pRbf/Brca1/p53失活的肿瘤和10个pRbf/p53失活的肿瘤）进行了综合分析。然后我们进行了流式细胞术分析、免疫染色、肿瘤球和细胞活力测定。
拷贝数畸变与基因组改变区域所涵盖基因的7.55%的转录水平相关。跨越4号和10号染色体大片段的反复基因组缺失包括几个细胞死亡基因。在扩增基因中，有众所周知的肿瘤发生驱动因子，包括无翅相关MMTV整合位点2（Wnt2），以及潜在的新驱动突变，包括晚期角质化包膜（LCE）基因家族。这些肿瘤具有干细胞/管腔祖细胞表型和活跃的β-连环蛋白信号传导。Wnt通路抑制剂可抑制肿瘤球形成和细胞存活。
我们的新型小鼠模型模拟了人类TNBC，并提供了一个平台来筛选恶性肿瘤进展背后的通路。
