Project description:A transgenic mouse model, MMTV-Wnt/ILK, with mammary specific expression of both Wnt-1 and ILK, was generated by crossing the two mouse lines MMTV-Wnt-1 and MMTV-ILK. Affymetrix Mouse Exon chips were hybridized with material from four independent mammary tumors from each MMTV-Wnt-1 and MMTV-Wnt/ILK transgenic model, in order to identify possible signaling differences involved during increased tumor incidence. One-way ANOVA: MMTV-Wnt vs. MMTV-Wnt/ILK
Project description:A transgenic mouse model, MMTV-Wnt/ILK, with mammary specific expression of both Wnt-1 and ILK, was generated by crossing the two mouse lines MMTV-Wnt-1 and MMTV-ILK. Affymetrix Mouse Exon chips were hybridized with material from four independent mammary tumors from each MMTV-Wnt-1 and MMTV-Wnt/ILK transgenic model, in order to identify possible signaling differences involved during increased tumor incidence.
Project description:The objective of this study was to determine the effect of Thyroid Hormone Responsive Protein Spot14 (Spot14) overexpression on the gene expression profiles of tumors from MMTV-Neu mice. Hemizygous MMTV-Neu and MMTV-Spot14 mice were bred and 1 cm tumors from Neu control or Neu/Spot14 bitransgenic offspring were profiled using Affymetrix gene arrays. Tumors from Neu/Spot14 mice emerged significantly earlier than controls, but expressed many genes associated with lactogenic differentiation and were not highly metastatic. These results from the mouse model are consistent with observations from primary human breast tumors, which indicate that high Spot14 gene expression was directly correlated with a luminal subtype and a positive ER status. Overexpression of Spot14 in cultured mammary epithelial cells stimulated proliferation but not differentiation. Together, these data suggest that, in vivo, Spot14 is expressed in well-differentiated cells, and promotes the expansion of this population in the context of oncogenic signaling pathway activation. Microarray analysis was performed on 13 mammary tumors from MMTV-Neu mice and 9 tumors from MMTV-Neu/MMTV-Spot14 mice.
Project description:We identified a 17-gene Her2-enriched tumor initiating cell (HTIC) signature in MMTV-Her2/Neu mouse mammary TICs. Here, we show that patients with HTICS+ HER2+:ERα− tumors are more likely to achieve a pathologic complete response to trastuzumab-based neoadjuvant chemotherapy compared with HER2+:ER+ tumors.
Project description:The objective of this study was to determine the effect of Thyroid Hormone Responsive Protein Spot14 (Spot14) overexpression on the gene expression profiles of tumors from MMTV-Neu mice. Hemizygous MMTV-Neu and MMTV-Spot14 mice were bred and 1 cm tumors from Neu control or Neu/Spot14 bitransgenic offspring were profiled using Affymetrix gene arrays. Tumors from Neu/Spot14 mice emerged significantly earlier than controls, but expressed many genes associated with lactogenic differentiation and were not highly metastatic. These results from the mouse model are consistent with observations from primary human breast tumors, which indicate that high Spot14 gene expression was directly correlated with a luminal subtype and a positive ER status. Overexpression of Spot14 in cultured mammary epithelial cells stimulated proliferation but not differentiation. Together, these data suggest that, in vivo, Spot14 is expressed in well-differentiated cells, and promotes the expansion of this population in the context of oncogenic signaling pathway activation.
Project description:Understanding the mechanisms underlying tumor heterogeneity is key to development of treatments that can target specific tumor subtypes. We have previously targeted CRE recombinase-dependent conditional deletion of the tumor suppressor genes Brca1, Brca2, p53 and/or Pten to basal or luminal ER- cells of the mouse mammary epithelium. We demonstrated that both the cell-of-origin and the tumor-initiating genetic lesions co-operate to influence mammary tumor phenotype. Here, we use a CRE-activated HER2 orthologue to specifically target HER2/ERBB2 oncogenic activity to basal or luminal ER- mammary epithelial cells and carry out a detailed analysis of the tumors which develop. We find that in contrast to our previous studies, basal epithelial cells are refractory to transformation by the activated NeuKI allele, with mammary epithelial tumor formation largely confined to luminal ER- cells. Histologically, the majority of tumors that developed were classified as either adenocarcinomas of no special type or metaplastic adenosquamous tumors. Remarkably, the former were more strongly associated with virgin animals and were typically characterised by amplification of the NeuNT/ErbB2 locus and activation of non-canonical WNT signalling. In contrast, tumors characterised by squamous metaplasia were associated with animals that had been through at least one pregnancy and typically had lower levels of NeuNT/ErbB2 locus amplification but had activated canonical WNT signalling. Squamous changes in these tumors were associated with activation of the Epidermal Differentiation Cluster. Thus, in this model of HER2 breast cancer, cell-of-origin, reproductive history, NeuNT/ErbB2 locus amplification, and the activation of specific branches of the WNT signalling pathway all interact to drive inter-tumor heterogeneity.
Project description:Understanding the mechanisms underlying tumor heterogeneity is key to development of treatments that can target specific tumor subtypes. We have previously targeted CRE recombinase-dependent conditional deletion of the tumor suppressor genes Brca1, Brca2, p53 and/or Pten to basal or luminal ER- cells of the mouse mammary epithelium. We demonstrated that both the cell-of-origin and the tumor-initiating genetic lesions co-operate to influence mammary tumor phenotype. Here, we use a CRE-activated HER2 orthologue to specifically target HER2/ERBB2 oncogenic activity to basal or luminal ER- mammary epithelial cells and carry out a detailed analysis of the tumors which develop. We find that in contrast to our previous studies, basal epithelial cells are refractory to transformation by the activated NeuKI allele, with mammary epithelial tumor formation largely confined to luminal ER- cells. Histologically, the majority of tumors that developed were classified as either adenocarcinomas of no special type or metaplastic adenosquamous tumors. Remarkably, the former were more strongly associated with virgin animals and were typically characterised by amplification of the NeuNT/ErbB2 locus and activation of non-canonical WNT signalling. In contrast, tumors characterised by squamous metaplasia were associated with animals that had been through at least one pregnancy and typically had lower levels of NeuNT/ErbB2 locus amplification but had activated canonical WNT signalling. Squamous changes in these tumors were associated with activation of the Epidermal Differentiation Cluster. Thus, in this model of HER2 breast cancer, cell-of-origin, reproductive history, NeuNT/ErbB2 locus amplification, and the activation of specific branches of the WNT signalling pathway all interact to drive inter-tumor heterogeneity.