Project description:ABSTRACT: Obesity is responsible for decreased overall survival for breast cancer patients. Here, we describe the generation, characterization and application of a novel murine mammary tumor initiating cell model (M-Wnt) that recapitulates the claudin-low subtype of human breast cancer and permits the study of TIC’s in wild-type, immunocompetent mice. M-Wnt cells readily form mammospheres in suspension culture, express markers consistent with epithelial-to-mesenchymal transition (EMT), and generate claudin-low mammary tumors when as few as 50 cells are orthotopically injected. Using the M-Wnt cell lines in tandem with a more basal-like epithelial breast cancer cell line, E-Wnt, we found that diet induced obesity significantly downregulates epithelial markers, such as E-cadherin, and upregulates mesenchymal markers including fibronectin, N-cadherin, SNAIL, Oct-4, and TGF-b. This reveals a previously unidentified link between energy balance and EMT. The ability of calorie restriction (CR) to reverse EMT, upregulate epithelial markers and downregulate mesenchymal markers indicates the plasticity of the TICs, as well as the potential importance of lifestyle modifications as cancer prevention strategies. 28 array samples
Project description:Claudin-low tumors are a highly aggressive breast cancer subtype with no targeted treatments and a clinically documented resistance to chemotherapy. They are significantly enriched in cancer stem cells (CSCs), which makes claudin-low tumor models particularly attractive for studying CSC behavior and developing novel approaches to minimize CSC therapy resistance. One proposed mechanism by which CSCs arise is via an epithelial-mesenchymal transition (EMT), and reversal of this process may provide a potential therapeutic approach for increasing tumor chemosensitivity. Therefore, we investigated the role of the miR-200 family of microRNAs in regulating the epithelial state, stem-like properties, and therapeutic response in an in vivo primary, syngeneic p53null claudin-low tumor model that is normally deficient in miR-200 expression. Using an inducible lentiviral approach, we expressed the miR-200c cluster in this claudin-low model and found that it changed the epithelial state, and consequently, impeded CSC behavior in these mesenchymal tumors. Moreover, these state changes were accompanied by a decrease in proliferation and an increase in the differentiation status. MiR-200c expression also forced a significant reorganization of tumor architecture, affecting important cellular processes involved in cell-cell contact, cell adhesion, and motility. Accordingly, induced miR200c expression also significantly enhanced the chemosensitivity and decreased the metastatic potential of this p53null claudin-low tumor model. Collectively, our data suggest that miR-200c expression in claudin-low tumors offers a potential therapeutic application to disrupt the EMT program on multiple fronts in this mesenchymal tumor subtype, by altering tumor growth, chemosensitivity, and metastatic potential in vivo. reference x sample
Project description:Expression of miR-200c in claudin-low breast cancer alters stem cell functionality, enhances chemosensitivity and reduces metastatic potential
Project description:ABSTRACT: Obesity is responsible for decreased overall survival for breast cancer patients. Here, we describe the generation, characterization and application of a novel murine mammary tumor initiating cell model (M-Wnt) that recapitulates the claudin-low subtype of human breast cancer and permits the study of TIC’s in wild-type, immunocompetent mice. M-Wnt cells readily form mammospheres in suspension culture, express markers consistent with epithelial-to-mesenchymal transition (EMT), and generate claudin-low mammary tumors when as few as 50 cells are orthotopically injected. Using the M-Wnt cell lines in tandem with a more basal-like epithelial breast cancer cell line, E-Wnt, we found that diet induced obesity significantly downregulates epithelial markers, such as E-cadherin, and upregulates mesenchymal markers including fibronectin, N-cadherin, SNAIL, Oct-4, and TGF-b. This reveals a previously unidentified link between energy balance and EMT. The ability of calorie restriction (CR) to reverse EMT, upregulate epithelial markers and downregulate mesenchymal markers indicates the plasticity of the TICs, as well as the potential importance of lifestyle modifications as cancer prevention strategies.
Project description:Claudin-low breast cancer represents an aggressive molecular subtype that is comprised of mostly triple-negative mammary tumor cells that possess stem cell-like and mesenchymal features. Little is known about the cellular origin and oncogenic drivers that promote claudin-low breast cancer. In this study, we show that persistent oncogenic RAS signaling causes highly metastatic triple-negative mammary tumors in mice. More importantly, the activation of endogenous mutant KRAS and expression of exogenous KRAS specifically in luminal epithelial cells in a continuous and differentiation stage-independent manner induces preneoplastic lesions that evolve into basal-like and claudin-low mammary cancers. Further investigations demonstrate that the continuous signaling of oncogenic RAS as well as regulators of EMT play a crucial role in the cellular plasticity and maintenance of the mesenchymal and stem cell characteristics of claudin-low mammary cancer cells.
Project description:Claudin-low tumors are a highly aggressive breast cancer subtype with no targeted treatments and a clinically documented resistance to chemotherapy. They are significantly enriched in cancer stem cells (CSCs), which makes claudin-low tumor models particularly attractive for studying CSC behavior and developing novel approaches to minimize CSC therapy resistance. One proposed mechanism by which CSCs arise is via an epithelial-mesenchymal transition (EMT), and reversal of this process may provide a potential therapeutic approach for increasing tumor chemosensitivity. Therefore, we investigated the role of the miR-200 family of microRNAs in regulating the epithelial state, stem-like properties, and therapeutic response in an in vivo primary, syngeneic p53null claudin-low tumor model that is normally deficient in miR-200 expression. Using an inducible lentiviral approach, we expressed the miR-200c cluster in this claudin-low model and found that it changed the epithelial state, and consequently, impeded CSC behavior in these mesenchymal tumors. Moreover, these state changes were accompanied by a decrease in proliferation and an increase in the differentiation status. MiR-200c expression also forced a significant reorganization of tumor architecture, affecting important cellular processes involved in cell-cell contact, cell adhesion, and motility. Accordingly, induced miR200c expression also significantly enhanced the chemosensitivity and decreased the metastatic potential of this p53null claudin-low tumor model. Collectively, our data suggest that miR-200c expression in claudin-low tumors offers a potential therapeutic application to disrupt the EMT program on multiple fronts in this mesenchymal tumor subtype, by altering tumor growth, chemosensitivity, and metastatic potential in vivo.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.
Project description:The claudin-low subtype is a recently identified rare molecular subtype of human breast cancer that expresses low levels of tight and adherens junction genes and shows high expression of epithelial-to-mesenchymal transition (EMT) genes. These tumors are enriched in gene expression signatures derived from human tumor initiating cells (TIC) and human mammary stem cells. Through cross-species analysis, we discovered mouse mammary tumors that have similar gene expression characteristics as human claudin-low tumors and were also enriched for the human TIC signature. Such claudin-low tumors were similarly rare, but came from a number of distinct mouse models including the p53 null transplant model. Here we present a molecular characterization of fifty p53 null mammary tumors as compared to other mouse models and human breast tumor subtypes. Similar to human tumors, the murine p53 null tumors fell into multiple molecular subtypes including two basal-like, a luminal, a claudin-low, and a subtype unique to this model. The claudin-low tumors also showed high gene expression of EMT inducers, low expression of the miR-200 family, and low to absent expression of both claudin 3 and E-cadherin. These murine subtypes also contained distinct genomic DNA copy number changes some of which are similarly altered in their cognate human subtype counterpart. Finally, limiting dilution transplantation revealed that p53 null claudin-low tumors are highly enriched for TICs as compared to the more common adenocarcinomas arising in the same model, thus providing a novel preclinical mouse model to investigate the therapeutic response of TICs. 107 Agilent CGH and expression microarrays
Project description:The claudin-low subtype is a recently identified rare molecular subtype of human breast cancer that expresses low levels of tight and adherens junction genes and shows high expression of epithelial-to-mesenchymal transition (EMT) genes. These tumors are enriched in gene expression signatures derived from human tumor initiating cells (TIC) and human mammary stem cells. Through cross-species analysis, we discovered mouse mammary tumors that have similar gene expression characteristics as human claudin-low tumors and were also enriched for the human TIC signature. Such claudin-low tumors were similarly rare, but came from a number of distinct mouse models including the p53 null transplant model. Here we present a molecular characterization of fifty p53 null mammary tumors as compared to other mouse models and human breast tumor subtypes. Similar to human tumors, the murine p53 null tumors fell into multiple molecular subtypes including two basal-like, a luminal, a claudin-low, and a subtype unique to this model. The claudin-low tumors also showed high gene expression of EMT inducers, low expression of the miR-200 family, and low to absent expression of both claudin 3 and E-cadherin. These murine subtypes also contained distinct genomic DNA copy number changes some of which are similarly altered in their cognate human subtype counterpart. Finally, limiting dilution transplantation revealed that p53 null claudin-low tumors are highly enriched for TICs as compared to the more common adenocarcinomas arising in the same model, thus providing a novel preclinical mouse model to investigate the therapeutic response of TICs.