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Supplementary Table 1. Kaplan-Meier survival statistics for control and experimental mice: This table presents results of analysis on tumor assays.

Supplementary Figure Legends 1-5

Supplementary Figures 1-5. Supplementary Fig. 1. Kaplan-Meier overall survival curves and cause of death data for control and experimental female mice. Supplementary Fig. 2. Mammary pathology analysis and estrogen receptor α staining for experimental mice. Supplementary Fig. 3. Activation of Stat3 and Mapk signaling in mouse mammary tumors. Supplementary Fig. 4. Ras pathway activation is associated with relapse and survival of breast cancer patients independent of PI3K and Stat3 pathway activation. Supplementary Fig. 5. PI3K pathway activation is associated with relapse of patients with Basal-like breast cancer.

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Supplementary Figure 8 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Tables 1-3 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 4 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 9 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 7 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure Legends from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 2 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 3 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 6 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 5 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

Supplementary Figure 1 from Cooperation between Pik3ca and p53 Mutations in Mouse Mammary Tumor Formation

The most common events in breast cancer (BC) involve chromosome arm losses and gains. Here we describe identification of 1089 gene-centric common insertion sites (gCIS) from transposon-based screens in 8 mouse models of BC. Some gCIS are driver-specific, others driver non-specific, and still others associated with tumor histology. Processes affected by driver-specific and histology-specific mutations include well-known cancer pathways. Driver non-specific gCIS target the Mediator complex, Ca++ signaling, Cyclin D turnover, RNA-metabolism among other processes. Most gCIS show single allele disruption and many map to genomic regions showing high-frequency hemizygous loss in human BC. Two gCIS, Nf1 and Trps1, show synthetic haploinsufficient tumor suppressor activity. Many gCIS act on the same pathway responsible for tumor initiation, thereby selecting and sculpting just enough and just right signaling. These data highlight ~1000 genes with predicted conditional haploinsufficient tumor suppressor function and the potential to promote chromosome arm loss in BC., Transposon based screens carried out in mice can identify genes critical for tumourigensis. Here, the authors describe transposon screens in mouse models of breast cancer and highlight a large group of tumour suppressors that could underlie selection for common chromosome arm losses in cancer.

SUMMARY CDH1 and PIK3CA are the two most frequently mutated genes in invasive lobular carcinoma (ILC) of the breast. Transcription profiling has identified molecular subtypes for ILC, one of which, immune-related (IR), is associated with gene expression linked to lymphocyte and macrophage infiltration. Here, we report that deletion of Cdh1, together with activation of Pik3ca in mammary epithelium of genetically modified mice, leads to formation of IR-ILC-like tumors with immune cell infiltration, as well as gene expression linked to T-regulatory (Treg) cell signaling and activation of targetable immune checkpoint pathways. Interestingly, these tumors show enhanced Rac1-and Yap-dependent transcription and signaling, as well as sensitivity to PI3K, Rac1, and Yap inhibitors in culture. Finally, high-dimensional immunophenotyping in control mouse mammary gland and IR-ILC tumors by mass cytometry shows dramatic alterations in myeloid and lymphoid populations associated with immune suppression and exhaustion, highlighting the potential for therapeutic intervention via immune checkpoint regulators., Graphical Abstract, In Brief An et al. describe the development and characterization of a mouse model for invasive lobular carcinoma (ILC) of the breast based on the two most mutated genes in human ILC. This model is analogous to immune-related ILC, shows myeloid and T cell alterations consistent with immune suppression and exhaustion, and represents a platform for therapeutics.

Summary Blood vessels are formed through vasculogenesis, followed by remodeling of the endothelial network through angiogenesis. Many events that occur during embryonic vascular development are recapitulated during adult neoangiogenesis, which is critical to tumor growth and metastasis. Current antiangiogenic tumor therapies, based largely on targeting the vascular endothelial growth factor pathway, show limited clinical benefits, thus necessitating the discovery of alternative targets. Here we report the development of a robust embryonic stem cell-based vascular differentiation assay amenable to small-molecule screens to identify novel modulators of angiogenesis. In this context, RSK and TTK were identified as angiogenic modulators. Inhibition of these pathways inhibited angiogenesis in embryoid bodies and human umbilical vein endothelial cells. Furthermore, inhibition of RSK and TTK reduced tumor growth, vascular density, and improved survival in an in vivo Lewis lung carcinoma mouse model. Our study suggests that RSK and TTK are potential targets for antiangiogenic therapy, and provides an assay system for further pathway screens., Highlights • Development of ESC-based vascular differentiation assay amenable to drug screening • Screening a kinase library identified RSK and TTK as angiogenic modulators • RSK and TTK inhibition disrupted angiogenesis in vitro • RSK and TTK inhibition inhibited Lewis lung tumor growth and angiogenesis in vivo, Rossant and colleagues developed a robust embryonic stem cell-based vascular differentiation assay, which was used to screen a small-molecule kinase library. They identified RSK and TTK as angiogenic modulators. Inhibition of these pathways inhibited angiogenesis in embryoid bodies and HUVECs in vitro, and reduced tumor growth and vascular density in an in vivo Lewis lung carcinoma mouse model.

Breast cancer is associated with alterations in a number of growth factor and hormone-regulated signaling pathways. Mouse models of metastatic breast cancer typically feature mutated oncoproteins that activate PI3K, Stat3, and Ras signaling, but the individual and combined roles of these pathways in breast cancer progression are poorly understood. In this study, we examined the relationship between oncogenic pathway activation and breast cancer subtype by analyzing mouse mammary tumor formation in which each pathway was activated singly or pairwise. All three oncogenes showed cooperation during primary tumor formation, but efficient dissemination was only dependent on Ras. In addition, transcriptional profiling demonstrated that Ras induced adenocarcinomas with molecular characteristics related to human basal-like and HER2+ tumors. In contrast, Ras combined with PIK3CAH1047R, an oncogenic mutant linked to ERα+/luminal breast cancer in humans, induced metastatic luminal B-like tumors. Consistent with these data, elevated Ras signaling was associated with basal-like and HER2+ subtype tumors in humans and showed a statistically significant negative association with estrogen receptor (ER) signaling across all breast cancer. Despite this, there are luminal tumors with elevated Ras signaling. Importantly, when considered as a continuous variable, Ras pathway activation was strongly linked to reduced survival of patients with ERα+ disease independent of PI3K or Stat3 activation. Therefore, our studies suggest that Ras activation is a key determinant for dissemination and poor prognosis of ERα+/luminal breast cancer in humans, and hormone therapy supplemented with Ras-targeting agents may be beneficial for treating this aggressive subtype. Cancer Res; 75(22); 4960–72. ©2015 AACR.

Jessica R. Adams 1,2 , Nathan F. Schachter 1,2 , Jeff C. Liu 3 , Eldad Zacksenhaus 3,4 and Sean E. Egan 1,2 1 Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 101 College St., East Tower 2 The Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada 3 Division of Cell and Molecular Biology, Toronto General Research Institute–University Health Network, Toronto, Ontario, Canada 4 The Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada Keywords: PIK3CA, Mouse models, Breast Cancer, PTEN, Akt, Metastasis Received: June 2, 2011; Accepted: June 2, 2011; Published: June 5, 2011; Correspondence: Sean E. Egan, e-mail: // // Abstract Most human breast tumors have mutations that elevate signaling through a key metabolic pathway that is induced by insulin and a number of growth factors. This pathway serves to activate an enzyme known as phosphatidylinositol 3’ kinase (PI3K) as well as to regulate proteins that signal in response to lipid products of PI3K. The specific mutations that activate this pathway in breast cancer can occur in genes coding for tyrosine kinase receptors, adaptor proteins linked to PI3K, catalytic and regulatory subunits of PI3K, serine/threonine kinases that function downstream of PI3K, and also phosphatidylinositol 3’ phosphatase tumor suppressors that function to antagonize this pathway. While each genetic change results in net elevation of PI3K pathway signaling, and all major breast cancer subtypes show pathway activation, the specific mutation(s) involved in any one tumor may play an important role in defining tumor subtype, prognosis and even sensitivity to therapy. Here, we describe mouse models of PI3K- breast cancer and how they may be used to guide development of novel therapeutics for treatment.

Stabilized β-catenin expression is a well described initiator of mammary tumorigenesis in the mouse and elevated nuclear expression has been observed in human triple-negative tumor samples. However, the importance of stabilized β-catenin to continued tumor growth after initiation, and in the context of other driver mutations, has yet to be elucidated. To ascertain the importance of stabilized β-catenin after tumor initiation, we generated a novel transgenic mouse model, utilizing the tet-off system, to control expression of stabilized β-catenin. Expression was tissue restricted through insertion of a stop cassette flanked by loxP sites upstream of stabilized β-catenin and firefly luciferase, which were coexpressed to allow repeated bioluminescent imaging of experimental mice. Insertion of the expression vector was targeted to the Rosa26 locus in R1 embryonic stem cells through homologous recombination. Following aggregation and chimera generation, two founder lines were established. Pups from early litters carrying one allele of regulatable stabilized β-catenin at the Rosa26 locus, but not targeted by Cre, were smaller in size compared with wild-type littermates. They also developed perianal skin lesions around 2-3 weeks of age, with severe necrosis evident by 3-4 weeks of age, requiring the animals to be euthanized. Backcrossing to the desired FVB strain did not alter development of skin lesions, which were observed in offspring from both founder lines. While aberrant gene expression was not observed in these animals, placing breeding females on doxycycline chow through pregnancy, up until pup weaning, eliminated the condition, suggesting a role for the tet machinery in the development of the condition. Maintenance of breeding cages on doxycycline chow allowed for healthy transgenic pups to survive past 3 weeks of age. Initially, six animal cohorts were established, along with control animals, using two different mammary Cre strains, WAP-Cre and MMTV-NLST-Cre, crossed with regulatable, stabilized β-catenin (St-bcatFL) animals, as well as animals expressing mutated p53-R270H. While mammary tumors developed in animals expressing Cre-targeted regulatable St-bcatFL, the penetrance and growth kinetics were lower than observed with other mammary mouse models expressing stabilized β-catenin. As significantly fewer animals developed tumors, we were only able to test the effect of turning off stabilized β-catenin expression following tumor initiation in a small number of animals, with tumor stasis but not regression observed in animals expressing Cre-targeted St-bcatFL, but not in animals expressing both St-bcatFL and p53-R270H. The regulatable St-bcatFL mice were also crossed with animals expressing mutant PIK3CA*E545K and MMTV-NLST-Cre, to examine the importance of stabilized β-catenin to the rapid tumor growth we have observed in mice expressing stabilized β-catenin through deletion of exon 3, and PIK3CA*E545K. While all of the PIK3CA*E545K;Exon3 fl/+; Cre+ animals examined developed multiple mammary tumors by 5 months of age, the PIK3CA*E545K;St-bcatFL;Cre+ mice failed to develop tumors within the same time period. These results indicate that mammary tumor development, including penetrance and growth kinetics, differs significantly between our novel regulatable stabilized β-catenin mouse model and other more aggressive models of stabilized β-catenin. These differences will require alternative methods to determine whether stabilized β-catenin expression is required for the long-term maintenance of tumor growth. Funding for this project was provided by the Terry Fox Foundation, as well as the Canadian Breast Cancer Foundation. Citation Format: Jennifer L. Gorman, Jessica R. Adams, Emma M. Jones, Sean E. Egan, James R. Woodgett. Generation of a novel transgenic mouse model with regulatable β-catenin expression to examine importance of activated β-catenin signaling to long-term maintenance of mammary tumor growth [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr A29.

SummaryBasal-like breast cancers (BLBC) express a luminal progenitor gene signature. Notch receptor signaling promotes luminal cell fate specification in the mammary gland, while suppressing stem cell self-renewal. Here we show that deletion of Lfng, a sugar transferase that prevents Notch activation by Jagged ligands, enhances stem/progenitor cell proliferation. Mammary-specific deletion of Lfng induces basal-like and claudin-low tumors with accumulation of Notch intracellular domain fragments, increased expression of proliferation-associated Notch targets, amplification of the Met/Caveolin locus, and elevated Met and Igf-1R signaling. Human BL breast tumors, commonly associated with JAGGED expression, elevated MET signaling, and CAVEOLIN accumulation, express low levels of LFNG. Thus, reduced LFNG expression facilitates JAG/NOTCH luminal progenitor signaling and cooperates with MET/CAVEOLIN basal-type signaling to promote BLBC.

PIK3CA, which codes for the p110α catalytic subunit of phosphatidylinositol 3-kinase, is one of the most frequently mutated genes in human breast cancer. Here, we describe a mouse model for PIK3CA-induced breast cancer by using the ROSA26 (R26) knock-in system, in which targeted Pik3ca alleles can be activated through transgenic expression of Cre recombinase. We mated Pik3caH1047R and Pik3cawt knock-in lines with MMTV-Cre transgenics, which express Cre in mammary epithelium. Starting at approximately 5 months of age, female R26-Pik3caH1047R;MMTV-Cre mice, but not control R26-Pik3cawt;MMTV-Cre mice, developed mammary tumors, as well as lymphoid and skin malignancies. R26-Pik3caH1047R;MMTV-Cre mammary tumors were typically either adenosquamous carcinoma or adenomyoepithelioma. As p53 is the most commonly mutated gene in breast cancer, we tested for genetic interaction between Pik3caH1047R and p53 loss-of-function mutations in R26-Pik3caH1047R;p53loxP/+;MMTV-Cre mice. This led to decreased survival of double-mutant animals, which developed lymphoma and mammary tumors with rapid kinetics. Mammary tumors that formed in p53loxP/+;MMTV-Cre conditional mutants were either poorly differentiated adenocarcinoma or spindle cell/EMT, whereas R26-Pik3caH1047R;p53loxP/+;MMTV-Cre mammary tumors were mostly adenosquamous carcinoma or spindle cell/EMT indicating that double-mutant mice develop a distinct spectrum of mammary tumors. Thus, an oncogenic variant of PIK3CA implicated in multiple human breast cancer subtypes can induce a very diverse spectrum of mammary tumors in mice. Furthermore, Pik3caH1047R shows cooperation with p53, which altered the specific tumors that formed. Thus, the two most frequently mutated genes in human breast cancer show cooperation in mammary tumor formation. Cancer Res; 71(7); 2706–17. ©2011 AACR.

Disorders of water metabolism are a common complication of pituitary surgery. The primary purpose of this study was to determine the incidence and duration of post-surgical diabetes insipidus (DI) at our institution. Secondary objectives included characterizing the incidence of post-operative hyponatremia as well as delineating factors associated with the onset of these complications. Records of 319 patients who underwent transsphenoidal pituitary surgery at the authors’ institution between 1998 and 2005 were reviewed for the presence of disorders of water metabolism using pre-specified criteria. DI was diagnosed in 59 (18.5%) of our patients at a mean time of 13.6 h following surgery. DI resolved in nearly half of our patients within one week. Approximately 80% of our patients enjoyed resolution of DI at a mean time of 2.9 months following surgery. Duration of DI was not significantly influenced by tumor size or location. Additionally, 28 (8.8%) of our patients exhibited a period of hyponatremia at a mean time of 4 days following surgery. One quarter of these patients carried a diagnosis of Cushing’s disease. We herein report an incidence of DI as well as hyponatremia within our post-operative population comparable to that reported by other high-volume pituitary centers. Over half of our patients still exhibited DI at the time of discharge, therefore, patient education regarding the treatment of DI, signs of its resolution, and symptoms consistent with the onset of hyponatremia should be an integral part of every hospitalization.

Background Human breast cancer is a heterogeneous disease consisting of multiple molecular subtypes. Genetically engineered mouse models are a useful resource for studying mammary cancers in vivo under genetically controlled and immune competent conditions. Identifying murine models with conserved human tumor features will facilitate etiology determinations, highlight the effects of mutations on pathway activation, and should improve preclinical drug testing. Results Transcriptomic profiles of 27 murine models of mammary carcinoma and normal mammary tissue were determined using gene expression microarrays. Hierarchical clustering analysis identified 17 distinct murine subtypes. Cross-species analyses using three independent human breast cancer datasets identified eight murine classes that resemble specific human breast cancer subtypes. Multiple models were associated with human basal-like tumors including TgC3(1)-Tag, TgWAP-Myc and Trp53-/-. Interestingly, the TgWAPCre-Etv6 model mimicked the HER2-enriched subtype, a group of human tumors without a murine counterpart in previous comparative studies. Gene signature analysis identified hundreds of commonly expressed pathway signatures between linked mouse and human subtypes, highlighting potentially common genetic drivers of tumorigenesis. Conclusions This study of murine models of breast carcinoma encompasses the largest comprehensive genomic dataset to date to identify human-to-mouse disease subtype counterparts. Our approach illustrates the value of comparisons between species to identify murine models that faithfully mimic the human condition and indicates that multiple genetically engineered mouse models are needed to represent the diversity of human breast cancers. The reported trans-species associations should guide model selection during preclinical study design to ensure appropriate representatives of human disease subtypes are used.