Project description:Background: Epithelial-mesenchymal transition (EMT) has been implicated in metastasis, drug resistance, survival under stress and also conferring stem cell-like traits to cancer cells. However, several of the studies have been carried out using model systems that don’t appropriately recapitulate all stages of the dynamic process of EMT. Hence, there is a need to overcome this limitation by development of a model system that allows us to mimic each stage of EMT and accurately assess the plastic changes associated with it. Methods: We have derived a cancer cell line from the PyMT-MMTV model of breast cancer, named PyMT-1099 cells, and undertaken a detailed characterization of the morpho-genetic changes it undergoes during a TGF-induced EMT. Further, we have also performed high throughput transcriptomics on PyMT-1099 cells undergoing EMT in a high resolution kinetic of TGF treatment. Results: We show that PyMT-1099 cells undergo an EMT comparable to the classically used immortalized NMuMG cells as assessed by morphological, and marker expression changes on TGFtreatment. Further, PyMT-1099 cells can also migrate in vitro in response to TGF treatment. These cells are also tumorigenic and lead to metastasis formation when transplanted into immunocompromised mice. Conclusion: In this study we report the development of PyMT-1099 cells as an excellent tool to model and study breast cancer-associated EMT both in vitro and in vivo and show that these cells overcome the limitations posed by other cellular systems currently being used to study EMT
Project description:Background: Epithelial-mesenchymal transition (EMT) has been implicated in metastasis, drug resistance, survival under stress and also conferring stem cell-like traits to cancer cells. However, several of the studies have been carried out using model systems that don’t appropriately recapitulate all stages of the dynamic process of EMT. Hence, there is a need to overcome this limitation by development of a model system that allows us to mimic each stage of EMT and accurately assess the plastic changes associated with it. Methods: We have derived a cancer cell line from the PyMT-MMTV model of breast cancer, named PyMT-1099 cells, and undertaken a detailed characterization of the morpho-genetic changes it undergoes during a TGFbeta-induced EMT. Further, we have also performed high throughput transcriptomics on PyMT-1099 cells undergoing EMT in a high resolution kinetic of TGFbeta treatment. Results: We show that PyMT-1099 cells undergo an EMT comparable to the classically used immortalized NMuMG cells as assessed by morphological, and marker expression changes on TGFbeta treatment. Further, PyMT-1099 cells can also migrate in vitro in response to TGFbeta treatment. These cells are also tumorigenic and lead to metastasis formation when transplanted into immunocompromised mice. Conclusion: In this study we report the development of PyMT-1099 cells as an excellent tool to model and study breast cancer-associated EMT both in vitro and in vivo and show that these cells overcome the limitations posed by other cellular systems currently being used to study EMT
Project description:An epithelial-mesenchymal transition (EMT) has been implicated in cancer metastasis, drug resistance, and in conferring stem cell-like traits to cancer cells. Most studies investigating EMT in cancer have either utilized immortalized or cancer cell lines that are already primed to undergo an EMT and do not adequately represent a fully differentiated epithelial state in the absence of an EMT induction. Hence, model systems are required which recapitulate all stages of EMT in cancer cells. Here, we report the derivation and characterization of epithelial PyMT-1099 cancer cells from the MMTV-PyMT mouse model of breast cancer. We demonstrate that PyMT-1099 cells undergo an EMT upon TGFβ treatment, while upon TGFβ withdrawal they go through a mesenchymal-epithelial transition (MET), as assessed by changes in cell morphology and marker expression and comparable to normal murine mammary gland NMuMG cells. However, in contrast to NMuMG cells, PyMT-1099 cells show an increase in cell migration and are highly tumorigenic and metastatic when transplanted into immunocompromised mice. Finally, we report cancer cell-specific changes in gene expression during EMT of PyMT-1099 cells not found in non-transformed NMuMG cells. Thus, PyMT-1099 cells are a versatile tool to study breast cancer-associated EMT and MET in vitro and in vivo.
Project description:Epithelial-mesenchymal transition (EMT) is a multistep process of cell de-differentiation which confers carcinoma cells with a variety of malignant characteristics. Due to the transient and reversible nature of the process, cancer cells may transit between various stages of an EMT continuum, including epithelial, partial EMT or full EMT, and the actual status of cancer cells, the kinetics of cellular state transition in vivo and the consequences thereof have remained elusive. We have established tamoxifen inducible dual recombinase lineage tracing systems combined with live cell imaging and 5-cell RNA-sequencing analysis to track cancer cells undergoing a partial or a full EMT in the MMTV-PyMT mouse model of metastatic breast cancer. In primary tumours, cancer cells infrequently undergo an EMT, and most of these cells transition between epithelial and partial EMT states, but rarely undergo a full EMT. Consequently, cells that have ever undergone a partial EMT dynamically transit between various EMT states, and they contribute to lung metastasis and chemoresistance. In contrast, full EMT cells mostly retain a mesenchymal phenotype and stably reside in perivascular regions, but fail to colonize the lungs. However, full EMT cancer cells are enriched in recurrent tumors upon chemotherapy. Our findings suggest that cancer cells in various stages of the EMT continuum contribute differentially to hallmarks of breast cancer malignancy, such as cell migration, invasion, metastasis and chemoresistance.
Project description:Analysis of differences at gene expression level of hpvE6 immortalized fibroblasts isolated from normal mammary glands and from hyperplasia, adenoma and carcinoma stages using the MMTV-PyMT model (FVB/N background). Analysis demonstrated the activation of specific transcriptional programs in fibroblasts from later stages. Total RNA obtained from isolated hpvE6 immortalized fibroblasts from normal mammary gland (NF) and from different stages of tumour development using the MMTV-PyMT murine breast cancer model. Stages were hyperplasia (HpAF), adenoma (AdAF) and carcinoma (CAF). Fibroblasts were seeded in a deformable Matrigel:collagen I matrix and total RNA isolated 72h later.
Project description:To study the contribution of epithelial-to-mesenchymal transition (EMT) in tumor metastasis, we established an EMT lineage tracing model in a multiple-transgenic mouse (MMTV-PyMT/Fsp1-Cre/Rosa26mT/mG, Tri-PyMT). In this model, breast tumor cells that underwent EMT would irreversibly switch their expression of the fluorescent marker from RFP+ to GFP+ due to the mesenchymal specific Cre expression. Surprisingly, we found that metastatic tumor cells did not convert from RFP+ to GFP+. Lung metastases were predominantly composed of RFP+ tumor cells persistently exhibiting epithelial phenotypes. These findings challenge the concept that EMT is required for metastasis, and have attracted vigorous discussion about its true contributions to metastasis. One of the major concerns with the EMT lineage tracing model is that expression of GFP only indicates the complete EMT transition. The partial-EMT programming, a novel concept describing tumor cells exhibiting both epithelial and mesenchymal features, could possibly fail to launch the Fsp1-Cre-mediated fluorescent marker switch. To address this concern, we evaluated the EMT status of Tri-PyMT cells on the single cell level by performing single cell RNA-sequencing (scRNA-seq). We found that the expression of epithelial markers (i.e. Epcam and Krt18) and mesenchymal markers (i.e. Vim and S110a4) were largely confined to RFP+ and GFP+ subpopulations, respectively. Based on the differentially expressed EMT related genes, we observed an EMT spectrum in which the low EMT score end was enriched with RFP+ cells, whereas the high EMT score end was enriched with GFP+ cells. Indeed, the fluorescent marker switch in Tri-PyMT cells predicted their EMT status with high specificity and sensitivity. Tri-PyMT cells which were derived from the primary breast tumor of triple transgenic mouse (MMTV-PyMT:Fsp1-cre:Rosa26mT/mG) were sorted into RFP+ or GFP+ populations by FACS and subjected for Drop-seq analysis.
Project description:Gene expression profiling of disseminated tumor cells in lung, lung metastatses and residual tumor cells in the MMTV-PyMT breast cancer model. Profiling gene expression change between disseminated tumor cells, lung metastases and residual tumor cells from the MMTV-PyMT breast cancer model.
Project description:Immortalized (hpv-E6) murine fibroblasts isolated from normal mammary glands and carcinoma stages (CAFs) from the MMTV-PyMT model (FVB/N background) were used in this analysis. CAFs were transfected with two independent RNAi targeting Dickkopf-3 (DKK3) or control RNAi and changes in whole-genome gene expression were evaluated by microarray. In addition, the effect of stable ectopic expression of DKK3 in normal fibroblasts (which normally do not express DKK3) was also evaluated. Analysis demonstrated the role of DKK3 in controlling specific transcriptional programs in CAFs.
Project description:Here, we use single cell sequencing to delineate the heterogeneity of tumours from the genetically engineered MMTV-PyMT mouse model of breast cancer (MMTV-PyMT::K14Cre::Rosa-tdTomato mice).