Project description:Murine models of mammary cancers have proven to be highly informative on numerous fronts including individual gene causation, microenvironmental analyses, and chemoprevention studies. The MMTV-Neu transgenic model of mammary cancer has proven to be a useful model and has been employed in several prevention studies. However, there are certain practical drawbacks to its use including long tumor latencies and a tendency to develop mutations in the transmembrane domain of Neu (unlike human HER2/Neu overexpressing breast cancers). Here we report modifications that were made in an attempt to optimize this mouse model for chemopreventive screening. First, homozygous MMTV-Neu and homozygous P53 KO mice were crossed to create a MMTV-Neu/P53+/- strain (which more closely approximates the genetic make-up of most HER2+ human patients). Second, to overcome the drawback of long tumor latencies, the mice were treated with DMBA for eight weeks. DMBA treatment greatly decreased the latency of mammary carcinomas in the MMTV-Neu mice although the resulting tumors remained histopathologically similar to those from MMTV-Neu control mice. Next, we examined gene expression in tumors derived from MMTV-Neu, MMTV-Neu/p53+/-, and DMBA treated mice. It was found that the characteristic MMTV-Neu tumor-defined expression pattern was still the most prevalent feature of all the MMTV-Neu tumors despite their being crossed to the p53 null allele, treated with DMBA, or both. However, tumors from the DMBA treated animals exhibited many unique gene expression changes including the high expression of stress response, defense, and inflammation genes. Finally, we demonstrated that the RXR agonists UAB30 and Targretin, both inhibited mammary cancer formation in MMTV-Neu mice, including those treated with DMBA. These results demonstrate the potential utility of this murine model for additional chemoprevention studies.
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:To identify early events of erbB2-induced mammary tumorigenesis, we compared datasets from 14 genechip experiments including MMTV-neu tumors, preneoplastic neu mammary gland (adjacent neu), and age-matched, wild-type control mammary glands
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:MicroRNAs (miRNAs) are small noncoding RNAs that typically inhibit the translation and stability of messenger RNAs (mRNAs), controlling genes involved in a variety of cellular processes. miRNA dysregulation is recognized to play an essential role in the development and progression of cancer. MMTV-PyMT mice (Jax Strain: FVB/N-Tg(MMTV-PyVT)634Mul/J) are a well-characterized transgenic mouse model of breast cancer. Upon activation of the MMTV-PyVT transgene (mouse mammary tumor virus (MMTV) long terminal repeat upstream of a cDNA sequence encoding the Polyoma Virus middle T antigen (PyVT)) female carriers develop palpable mammary tumors as early as 5 weeks of age. We performed miRNA microarrays on samples from the MMTV-PyMT transgenic mouse model to investigate the differential expression of miRNAs during development of malignant disease in this model.
Project description:CDC25A is a critical target of checkpoint, and its overexpression is observed in various cancers. Here we demonstrate that in vivo levels of Cdc25A expression determine the efficiency of transformation and tumorigenesis. Transgenic expression of CDC25A in murine mammary glands cooperates with tumorigenesis induced by expression of ras or neu. CDC25A- overexpressing tumors display aggressiveness and genomic instability with changes in fragile chromosomal regions, including the region orthologous to human 1p32-36. Experiment Overall Design: Tumors from two mice from each of two conditions (MMTV-cdc25a;MMTV-neu and MMTV-neu) were analyzed in a dye swap experiment. A total of four hybridizations were performed.
