BACKGROUND PIK3CA mutations are frequent in human breast cancer. Pik3caH1047R mutant expression in mouse mammary gland promotes tumorigenesis. TP53 mutations co-occur with PIK3CA mutations in human breast cancers. We previously generated a conditionally activatable Pik3caH1047R;MMTV-Cre mouse model and found a few malignant sarcomatoid (spindle cell) carcinomas that had acquired spontaneous dominant-negative Trp53 mutations. METHODS A Pik3caH1047R;Trp53R270H;MMTV-Cre double mutant mouse breast cancer model was generated. Tumors were characterized by histology, marker analysis, transcriptional profiling, single-cell RNA-seq, and bioinformatics. Cell lines were developed from mutant tumors and used to identify and confirm genes involved in metastasis. RESULTS We found Pik3caH1047R and Trp53R270H cooperate in driving oncogenesis in mammary glands leading to a shorter latency than either alone. Double mutant mice develop multiple histologically distinct mammary tumors, including adenocarcinoma and sarcomatoid (spindle cell) carcinoma. We found some tumors to be invasive and a few metastasized to the lung and/or the lymph node. Single-cell RNA-seq analysis of the tumors identified epithelial, stromal, myeloid, and T cell groups. Expression analysis of the metastatic tumors identified S100a4 as a top candidate gene associated with metastasis. Metastatic tumors contained a much higher percentage of epithelial-mesenchymal transition (EMT)-signature positive and S100a4-expressing cells. CRISPR/CAS9-mediated knockout of S100a4 in a metastatic tumor-derived cell line disrupted its metastatic potential indicating a role for S100a4 in metastasis. CONCLUSIONS Pik3caH1047R;Trp53R270H;MMTV-Cre mouse provides a preclinical model to mimic a subtype of human breast cancers that carry both PIK3CA and TP53 mutations. It also allows for understanding the cooperation between the two mutant genes in tumorigenesis. Our model also provides a system to study metastasis and develop therapeutic strategies for PIK3CA/TP53 double-positive cancers. S100a4 found involved in metastasis in this model can be a potential diagnostic and therapeutic target.

中文翻译：

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Pik3caH1047R; Trp53R270H; MMTV-Cre驱动的乳腺肿瘤中的S100a4上调促进转移。

背景技术PIK3CA突变在人类乳腺癌中很常见。Pik3caH1047R突变体在小鼠乳腺中的表达促进肿瘤发生。TP53突变与人乳腺癌中的PIK3CA突变同时发生。我们先前生成了有条件可激活的Pik3caH1047R; MMTV-Cre小鼠模型，并发现了一些获得自发显性负性Trp53突变的恶性肉瘤样（纺锤状细胞）癌。方法建立了Pik3caH1047R; Trp53R270H; MMTV-Cre双重突变小鼠乳腺癌模型。通过组织学，标记分析，转录谱，单细胞RNA-seq和生物信息学对肿瘤进行表征。细胞系是从突变的肿瘤中发展而来的，用于鉴定和确认与转移有关的基因。结果我们发现Pik3caH1047R和Trp53R270H在乳腺肿瘤发生发展中具有协同作用，从而导致潜伏期短于任何一个。双突变小鼠发展出多种组织学上不同的乳腺肿瘤，包括腺癌和肉瘤样（纺锤状细胞）癌。我们发现一些肿瘤是浸润性的，少数转移到肺和/或淋巴结。对肿瘤的单细胞RNA序列分析确定了上皮，基质，髓样和T细胞组。转移性肿瘤的表达分析确定S100a4是与转移相关的最佳候选基因。转移性肿瘤包含上皮-间质转化（EMT）-签名阳性和表达S100a4的细胞百分比更高。CRISPR / CAS9介导的转移性肿瘤衍生细胞系中S100a4的敲除破坏了其转移潜能，表明S100a4在转移中的作用。结论Pik3caH1047R; Trp53R270H; MMTV-Cre小鼠提供了一种临床前模型，可模拟携带PIK3CA和TP53突变的人类乳腺癌亚型。它还允许理解两个突变基因在肿瘤发生中的合作。我们的模型还提供了一个系统来研究PIK3CA / TP53双阳性癌症的转移并制定治疗策略。在该模型中发现与转移有关的S100a4可能是潜在的诊断和治疗靶标。MMTV-Cre小鼠提供了一种临床前模型，可模拟携带PIK3CA和TP53突变的人类乳腺癌亚型。它还允许理解两个突变基因在肿瘤发生中的合作。我们的模型还提供了一个系统来研究PIK3CA / TP53双阳性癌症的转移并制定治疗策略。在该模型中发现与转移有关的S100a4可能是潜在的诊断和治疗靶标。MMTV-Cre小鼠提供了一种临床前模型，可模拟携带PIK3CA和TP53突变的人类乳腺癌亚型。它还允许理解两个突变基因在肿瘤发生中的合作。我们的模型还提供了一个系统来研究PIK3CA / TP53双阳性癌症的转移并制定治疗策略。在该模型中发现与转移有关的S100a4可能是潜在的诊断和治疗靶标。