Project description:We previously identified a novel SNF1/AMPK-related protein kinase, Hunk, from a mammary tumor arising in an MMTV-neu transgenic mouse. The function of this kinase is unknown. Using targeted deletion in mice, we now demonstrate that Hunk is required for the metastasis of c-myc-induced mammary tumors, but is dispensable for normal development. Reconstitution experiments revealed that Hunk is sufficient to restore the metastatic potential of Hunk-deficient tumor cells, as well as defects in migration and invasion, and does so in a manner that requires its kinase activity. Consistent with a role for Hunk in the progression of human cancers, the human homologue of Hunk is overexpressed in aggressive subsets of carcinomas of the ovary, colon, and breast. In addition, a murine gene expression signature that distinguishes Hunk-wild type from Hunk-deficient mammary tumors predicts clinical outcome in women with breast cancer. Together, these findings establish a role for Hunk in metastasis and an in vivo function for this kinase.
Project description:We previously identified a novel SNF1/AMPK-related protein kinase, Hunk, from a mammary tumor arising in an MMTV-neu transgenic mouse. The function of this kinase is unknown. Using targeted deletion in mice, we now demonstrate that Hunk is required for the metastasis of c-myc-induced mammary tumors, but is dispensable for normal development. Reconstitution experiments revealed that Hunk is sufficient to restore the metastatic potential of Hunk-deficient tumor cells, as well as defects in migration and invasion, and does so in a manner that requires its kinase activity. Consistent with a role for Hunk in the progression of human cancers, the human homologue of Hunk is overexpressed in aggressive subsets of carcinomas of the ovary, colon, and breast. In addition, a murine gene expression signature that distinguishes Hunk-wild type from Hunk-deficient mammary tumors predicts clinical outcome in women with breast cancer. Together, these findings establish a role for Hunk in metastasis and an in vivo function for this kinase. Hunk-deficient animals were crossed to mice harboring an MMTV-c-myc transgene (Leder et al., 1986). Hunk heterozygous, MMTV-c-myc mice were backcrossed to Hunk heterozygous animals. MMTV-c-myc female animals of each Hunk genotype were mated twice, then monitored twice weekly for mammary tumors. Mice possessing tumors with a maximum diameter of 20 mm were sacrificed and organs were examined at necropsy. Tumor nodules were identified by examination of organs through a Leica Wild MZ8 dissection microscope.
Project description:ErbB-2 overexpression and amplification occurs in 15 - 30% of human invasive breast carcinomas associated with poor clinical prognosis. Previously, we have demonstrated that four ErbB-2/Neu tyrosine-autophosphorylation sites within the cytoplasmic tail of the receptor recruit distinct adaptor proteins and are sufficient to mediate transforming signals in vitro. Two of these sites representing the Grb2 (Neu-YB) and Shc (Neu-YD) binding sites can induce mammary tumourigenesis and metastasis. Here we show that Neu-YC and Neu-YE transgenic mice develop metastatic mammary tumours. A detailed comparison of pathological and transcriptional profiles among all Neu mutant mouse models revealed that Neu-YC, -YD and -YE mammary tumours shared similar pathological and transcriptional features correlating with their capacity to signal through a common adaptor like Shc. In contrast, the Neu-YB mouse model displayed a unique pathology with a high metastatic potential that correlates with a distinct transcriptional profile. We identified genes specifically expressed in YB-induced mammary tumours, including CXCL12/SDF-1α that promotes malignant tumour progression. Furthermore, Neu-YB tumour epithelial cells showed abundant intracellular CXCL12/SDF-1α protein, which may reflect the more aggressive phenotype among all Neu mutant mouse models. These findings indicate that activation of distinct Neu-coupled signalling pathways has a deep impact on the biological behaviour of Neu-induced tumours. Keywords: genetic modification, Neu mutant mouse models, mammary tumor
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 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:Copy number gains in genes coding for Rho activating exchange factors as well as losses affecting genes coding for RhoGAP proteins are common in breast cancer, suggesting that elevated Rho signaling may play an important role. Extra copies and overexpression of RhoC also occur, although a role for RhoC overexpression in driving tumor formation has not been assessed in vivo. To this end, we report on the development of a Rosa26 (R26)-targeted Cre-conditional RhoC overexpression mouse (R26-RhoC). This mouse was crossed to two models for ERBB2/NEU+ breast cancer: one based on expression of an oncogenic ErbB2/Neu cDNA downstream of the endogenous ErbB2 promoter (FloxNeoNeuNT), the other, a metastatic model that is based on high-level expression from MMTV regulatory elements (NIC). RhoC overexpression dramatically enhanced mammary tumor formation in FloxNeoNeuNT mice but showed a more subtle effect in the NIC line, which forms multiple mammary tumors after a very short latency. Many mammary tumors that form in FloxNeoNeuNT mice show selection for increased NeuNT expression linked to high-level amplification of the ErbB2/NeuNT locus. In contrast, NeuNT overexpression did not require high-level amplification of ErbB2/NeuNT in RhoC-FloxNeoNeuNT lesions. RhoC overexpression also enhanced mammary tumor formation in a model for breast cancer induced by Pik3ca(H1047R). The transforming effect of RhoC was associated with epithelial/mesenchymal transition (EMT) in ErbB2/NeuNT and Pik3ca-H1047R systems. Thus, RhoC copy number gains with resultant overexpression contribute to breast tumor formation and/or progression.
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: Genomic DNA from a MMTV-cdc25a;MMTV-neu double transgenic murine cell line derived from a mammary tumor was compared to normal mammary tissue DNA from the parental strain. A total of two hybridizations were completed.
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: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.