Targeted Pten deletion plus p53-R270H mutation in mouse mammary epithelium induces aggressive claudin-low and basal-like breast cancer

Abstract

BackgroundTriple-negative breast cancer (TNBC), an aggressive disease comprising several subtypes including basal-like and claudin-low, involves frequent deletions or point mutations in TP53, as well as loss of PTEN. We previously showed that combined deletion of both tumor suppressors in the mouse mammary epithelium invariably induced claudin-low-like TNBC. The effect of p53 mutation plus Pten deletion on mammary tumorigenesis and whether this combination can induce basal-like TNBC in the mouse are unknown.MethodsWAP-Cre:Ptenf/f:p53lox.stop.lox_R270H composite mice were generated in which Pten is deleted and a p53-R270H mutation in the DNA-binding domain is induced upon expression of Cre-recombinase in pregnancy-identified alveolar progenitors. Tumors were characterized by histology, marker analysis, transcriptional profiling [GEO-GSE75989], bioinformatics, high-throughput (HTP) FDA drug screen as well as orthotopic injection to quantify tumor-initiating cells (TICs) and tail vein injection to identify lung metastasis.ResultsCombined Pten deletion plus induction of p53-R270H mutation accelerated formation of four distinct mammary tumors including poorly differentiated adenocarcinoma (PDA) and spindle/mesenchymal-like lesions. Transplantation assays revealed highest frequency of TICs in PDA and spindle tumors compared with other subtypes. Hierarchical clustering demonstrated that the PDA and spindle tumors grouped closely with human as well as mouse models of basal and claudin-low subtypes, respectively. HTP screens of primary Pten∆:p53∆ vs. Pten∆:p53R270H spindle tumor cells with 1120 FDA-approved drugs identified 8-azaguanine as most potent for both tumor types, but found no allele-specific inhibitor. A gene set enrichment analysis revealed increased expression of a metastasis pathway in Pten∆:p53R270H vs. Pten∆:p53∆ spindle tumors. Accordingly, following tail vein injection, both Pten∆:p53R270H spindle and PDA tumor cells induced lung metastases and morbidity significantly faster than Pten∆:p53∆ double-deletion cells, and this was associated with the ability of Pten∆:p53R270H tumor cells to upregulate E-cadherin expression in lung metastases.ConclusionsOur results demonstrate that WAP-Cre:Ptenf/f:p53lox.stop.lox_R270H mice represent a tractable model to study basal-like breast cancer because unlike p53 deletion, p53R270H mutation in the mouse does not skew tumors toward the claudin-low subtype. The WAP-Cre:Ptenf/f:p53lox.stop.lox_R270H mice develop basal-like breast cancer that is enriched in TICs, can readily form lung metastasis, and provides a preclinical model to study both basal-like and claudin-low TNBC in immune-competent mice.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-015-0668-y) contains supplementary material, which is available to authorized users.

microRNA-143/145 loss induces Ras signaling to promote aggressive Pten-deficient basal-like breast cancer

“…This is in stark contrast to multiple other mammary tumor models in which TICs were readily identified by our group and others (13,29,30,(60)(61)(62). One possible explanation is that AME tumor cells are dependent on estrogen signaling, thus unable to survive and proliferate in recipient mice without exogenous β-estradiol.…”

“…Indeed, our group showed that combined deletion or mutation in p53 cooperates with pten deficiency to accelerate aggressive, transplantable TNBC-like tumors (13,62). As noted, prostatespecific inactivation of pten also induces benign tumors with increased p53-dependent senescence (11,12).…”

RB1 deficiency in triple-negative breast cancer induces mitochondrial protein translation

“…The Sequoia Library (Pangbourne, United Kingdom) was screened as previously described (33,90). Chemicals were purchased from Sigma-Aldrich (doxorubicin, epirubicin, idarubicin, SSZ); Selleck Chemicals (sunitinib, salinomycin, TIG, crizotinib); Tocris (WAY 170523); and Sequoia Research Products (TIG).…”

“…Specifically, we transplanted primary MECs from MMTV-Cre Rb fl/fl p53 fl/fl females or from mid-pregnancy (15 dpc) Wap-Cre Rb fl/fl p53 fl/fl females (using the whey acidic protein [Wap] Cre, which targets alveolar progenitors) (31), into mammary glands of the recipient mice ( Figure 3). We also monitored cohorts of nulliparous MMTV-Cre NLST Rb fl/fl p53 fl/fl and MMTV-Cre Rb fl/fl p53 LSLR270H/+ animals, in which Rb is deleted together with p53, or in which a p53-R270H point mutation is expressed (5,32,33). Many of these transgenic mice succumbed to lymphomas, but surviving animals developed mammary tumors, albeit with longer latency.…”

Phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog as therapeutic targets in breast cancer

“…Burnett et al 131 reported that trastuzumab resistance stimulates EMT to transform HER2 (+) PTEN (−) to a TN-BCa that necessitates unique treatment options. Wang et al 132 reported that targeted PTEN deletion plus p53-R270H mutation in mouse mammary epithelium stimulates aggressive claudin-low and basal-like BCa.…”