Project description:To identify genes that may facilitate early steps of ErbB2/Neu-mediated mammary tumorigenesis, we performed comparative microarray analysis of 5- and 10-week bitransgenic mammary glands (LHxMMTV-neu) in triplicate. Keywords: transgenic mouse, erbB2, MMTV-neu, HER2, mammary tumor, breast cancer
Project description:To identify genes that may facilitate early steps of ErbB2/Neu-mediated mammary tumorigenesis, we performed comparative microarray analysis of 5- and 10-week bitransgenic mammary glands (LHxMMTV-neu) in triplicate. Experiment Overall Design: We analyzed 3 pooled RNA samples that represented 3 animals for each time point so that a total of 9 bitransgenic mice were analyzed per time point.
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: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.
Project description:Cancer is considered as a disease of a specific organ, but its effects are felt throughout the body. The systemic effects of cancer can lead to weakness in muscles and heart, which hastens cancer-associated death. miR-486 is a myogenic microRNA and its reduced expression in skeletal muscle is observed in muscular dystrophy. Muscle-specific transgenic expression of miR-486 using muscle creatine kinase promoter (MCK-miR-486) partially rescues skeletal muscle defects in muscular dystrophy animal models. We had previously demonstrated reduced circulating and skeletal muscle levels of miR-486 in several cancer types and lower miR-486 levels correlated with skeletal muscle defects and functional limitations in mammary tumor models. Therefore, skeletal muscle defects induced by cancer could resemble defects observed in various dystrophies, which could be reversed through skeletal muscle expression of miR-486. We performed functional limitations studies and biochemical analysis of skeletal muscles of MMTV-Neu transgenic mice that mimic HER2+ breast cancer and MMTV-PyMT transgenic mice that mimic luminal subtype B breast cancer and these mice crossed to MCK-miR-486 transgenic mice. miR-486 significantly prevented tumor-induced reduction in muscle contraction force, grip strength, and rotarod performance in MMTV-Neu, but not in MMTV-PyMT mice. In MMTV-Neu model, miR-486 reversed several of the cancer-induced changes in skeletal muscle including loss of p53, phospho-AKT, and phospho-laminin alpha 2 (LAMA2) and gain of phosphorylation of the pre-mRNA processing factor hnRNPA0 and the splicing factor SRSF10. LAMA2 is a part of the dystrophin-associated glycoprotein complex, and its loss-of-function mutation is associated with congenital muscular dystrophy. Thus, similar to muscular dystrophy, miR-486 has the potential to reverse skeletal muscle defects and cancer burden in select cancer types.
Project description:Analysis of mammary glands from tet-inducible(rtTA) transgenic mice expressing cyclin D1 using Affymetrix Mouse Gene 1.0 ST GeneChip arrays. MMTV-rtTA transgenic mice (MMTV-Mouse Mammary Tumor Virus promoter) were cross-mated to cyclin D1 transgenic mice under control of tet operon. 8-week-old tetracycline-inducible cyclin D1/rtTA bi-transgenic pregnant female mice (12 days postcoitus) were treated with doxycycline through drinking water supplementation at a final concentration of 2 mg/ml. Control mice were rtTA transgenics alone and treated in the same manner. After 7 days of doxycycline treatment, the mice were sacrificed and mammary glands taken for RNA isolation. Results provide insight into the in vivo gene expression pattern regulated by cyclin D1 through acute induction. Analysis of mammary glands from MMTV-cyclin D1/WT and MMTV-cyclin D1/KE using Affymetrix Mouse 430A v2.0 GeneChip arrays. Cyclin D1 point mutant, cyclin D1/KE K112E (K112E) contains a lysine to glutamine substitution at amino acid position 112. cyclin D1. The cyclin D1/KE mutant fails to induce cyclin D1-dependent kinase activity. Female MFD1, MFD1-KE, and WT mice were monitored twice weekly, up to 760 days, for the development of palpable tumors. Those developing palpable tumors were sacrificed within a week of tumor detection. Tumors were dissected and portions snap frozen for RNA isolation. Results provide insight into the in vivo gene expression pattern regulated by cyclin D1 that is kinase independent. Two separate control mice were positive for MMTV-rtTA transgene compared to 3 separate cyclin D1/rtTA bitransgenic female mice and 3 separate cyclin D1 KE mutant/rtTA bitransgenic female mice (Mouse Gene 1.0 ST arrays). Three separate control WT FvBmice were compared to three MMTV-cyclin D1/WT and 3 MMTV-cyclin D1/KE mice (Mouse 430A v2.0 arrays).
Project description:The objective of this study was to determine the effect of Thyroid Hormone Responsive Protein Spot14 (Spot14) loss on the gene expression profiles of tumors from MMTV-Polyomavirus middle-T antigen (PyMT) mice. MMTV-PyMT/S14-heterozygous mice were crossed with S14-heterozygous mice and 1 cm tumors from MMTV-PyMT control (wild-type S14) or MMTV-PyMT/S14-null offspring were profiled using Affymetrix gene arrays. Tumor latency was not different between groups; however, tumors lacking S14 grew significantly slower than control tumors. Loss of S14 also decreased the levels of de novo synthesized fatty acids in mammary tumors. In additional studies, performed on MMTV-Neu mice, we found that S14 overexpression was associated with increased tumor cell proliferation and elevated levels of tumor fatty acids. Gene expression profiling revealed that S14 loss and overexpression in mouse mammary tumors altered pathways associated with proliferation and metabolism. This study provides important information about the role of S14 in mammary tumorigenesis and tumor metabolism.
Project description:The objective of this study was to determine the effect of Thyroid Hormone Responsive Protein Spot14 (Spot14) loss on the gene expression profiles of tumors from MMTV-Polyomavirus middle-T antigen (PyMT) mice. MMTV-PyMT/S14-heterozygous mice were crossed with S14-heterozygous mice and 1 cm tumors from MMTV-PyMT control (wild-type S14) or MMTV-PyMT/S14-null offspring were profiled using Affymetrix gene arrays. Tumor latency was not different between groups; however, tumors lacking S14 grew significantly slower than control tumors. Loss of S14 also decreased the levels of de novo synthesized fatty acids in mammary tumors. In additional studies, performed on MMTV-Neu mice, we found that S14 overexpression was associated with increased tumor cell proliferation and elevated levels of tumor fatty acids. Gene expression profiling revealed that S14 loss and overexpression in mouse mammary tumors altered pathways associated with proliferation and metabolism. This study provides important information about the role of S14 in mammary tumorigenesis and tumor metabolism. Microarray analysis was performed on 4 mammary tumors from MMTV-PyMT mice and 4 tumors from MMTV-PyMT/S14-null mice.