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Combined deletion of Pten and p53 in mammary epithelium accelerates triple-negative breast cancer with dependency on eEF2K.

ABSTRACT: The tumor suppressors Pten and p53 are frequently lost in breast cancer, yet the consequences of their combined inactivation are poorly understood. Here, we show that mammary-specific deletion of Pten via WAP-Cre, which targets alveolar progenitors, induced tumors with shortened latency compared to those induced by MMTV-Cre, which targets basal/luminal progenitors. Combined Pten-p53 mutations accelerated formation of claudin-low, triple-negative-like breast cancer (TNBC) that exhibited hyper-activated AKT signaling and more mesenchymal features relative to Pten or p53 single-mutant tumors. Twenty-four genes that were significantly and differentially expressed between WAP-Cre:Pten/p53 and MMTV-Cre:Pten/p53 tumors predicted poor survival for claudin-low patients. Kinome screens identified eukaryotic elongation factor-2 kinase (eEF2K) inhibitors as more potent than PI3K/AKT/mTOR inhibitors on both mouse and human Pten/p53-deficient TNBC cells. Sensitivity to eEF2K inhibition correlated with AKT pathway activity. eEF2K monotherapy suppressed growth of Pten/p53-deficient TNBC xenografts in vivo and cooperated with doxorubicin to efficiently kill tumor cells in vitro. Our results identify a prognostic signature for claudin-low patients and provide a rationale for using eEF2K inhibitors for treatment of TNBC with elevated AKT signaling.

SUBMITTER: Liu JC

PROVIDER: S-EPMC4287974 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Combined deletion of Pten and p53 in mammary epithelium accelerates triple-negative breast cancer with dependency on eEF2K.

Liu Jeff C JC Voisin Veronique V Wang Sharon S Wang Dong-Yu DY Jones Robert A RA Datti Alessandro A Uehling David D Al-awar Rima R Egan Sean E SE Bader Gary D GD Tsao Ming M Mak Tak W TW Zacksenhaus Eldad E

EMBO molecular medicine 20141201 12

The tumor suppressors Pten and p53 are frequently lost in breast cancer, yet the consequences of their combined inactivation are poorly understood. Here, we show that mammary-specific deletion of Pten via WAP-Cre, which targets alveolar progenitors, induced tumors with shortened latency compared to those induced by MMTV-Cre, which targets basal/luminal progenitors. Combined Pten-p53 mutations accelerated formation of claudin-low, triple-negative-like breast cancer (TNBC) that exhibited hyper-act ...[more]

PMID: 25330770

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Project description: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:Pten(f/f):p53(lox.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(∆):p53(R270H) 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(∆):p53(R270H) vs. Pten(∆):p53(∆) spindle tumors. Accordingly, following tail vein injection, both Pten(∆):p53(R270H) 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(∆):p53(R270H) tumor cells to upregulate E-cadherin expression in lung metastases.ConclusionsOur results demonstrate that WAP-Cre:Pten(f/f):p53(lox.stop.lox_R270H) mice represent a tractable model to study basal-like breast cancer because unlike p53 deletion, p53(R270H) mutation in the mouse does not skew tumors toward the claudin-low subtype. The WAP-Cre:Pten(f/f):p53(lox.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.

Project description:To model the effect of Pten loss on breast cancer, we deleted Pten using a floxed allele and the deleter lines MMTV-Cre(NLST), which targets stem/bi-potent progenitor cells, and WAP-Cre, which targets CD24-positive, pregnancy-identified stem cells/alveolar progenitors. Mammary tumors were detected in WAP-Cre:Ptenf/f females with a latency of 15.2 months. By 18 months, nearly all mice had succumbed to cancer. MMTV-Cre:Ptenf/f mice developed mammary tumors after a longer latency of 26.4 months and reduced penetrance (70%) compared to WAP-Cre:Ptenf/f mice. Tumors from both models were heterogeneous, consisting primarily of differentiated adenocarcinoma (adenomyoepithelioma; ~70%) and adenosquamous carcinoma (20-25%). In addition, a small fraction of tumors was classified as acinar and poorly differentiated adenocarcinoma (4-7%) and adenosarcoma (3-4%). To test the consequences of combined Pten and p53 gene mutation on breast cancer, we deleted both genes via MMTV-Cre or WAP-Cre. Kaplan-Meier tumor free survival curves revealed that WAP-Cre:Ptenf/f:p53f/f and MMTV-Cre:Ptenf/f:p53f/f females developed tumors with reduced latency of 11.3 and 9.8 months, compared with 15.2, 26.4, and 16.9 months for single-mutant WAP-Cre:Ptenf/f, MMTV-Cre:Ptenf/f or MMTV-Cre:p53f/f mice, respectively. In contrast to the heterogeneity of Pten tumors and small percentage of adenosarcomas in these mice, ~70% of Pten:p53 lesions were histologically classified as adeno-sacrcomatoid-like or mesenchymal-like breast cancer, with the rest exhibiting mixed mesenchymal plus adenocarcinomas and differentiated adenocarcinomas. The adeno-sacrcomatoid-like tumors expressed the mesenchymal markers vimentin, K5, SMA, N-cadherin and desmin but not ER, as well as islands of luminal-like K18 expressing cells surrounded by a layer of K14-positive cells. We used microarrays to detect differentially expressed genes in the Pten:p53 double-knock-out vs Pten or p53 single deletions Total RNA was extracted from tumors developed by double Trizol method and hybridized on Affymetrix microarrays.

Dataset Information

Combined deletion of Pten and p53 in mammary epithelium accelerates triple-negative breast cancer with dependency on eEF2K.

Publications

Combined deletion of Pten and p53 in mammary epithelium accelerates triple-negative breast cancer with dependency on eEF2K.

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