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Medicine Lodge, United States

Gutierrez C.,Lester and Sue Smith Breast Center | Schiff R.,Baylor College of Medicine
Archives of Pathology and Laboratory Medicine | Year: 2011

Context.-HER2 is a membrane tyrosine kinase and oncogene that is overexpressed and gene amplified in about 20% of breast cancers. When activated it provides the cell with potent proliferative and antiapoptosis signals and it is the major driver of tumor development and progression for this subset of breast cancer. When shown to be overexpressed or amplified by appropriate methods, HER2 is a valuable treatment target. Objectives.-To review the basic biology of the HER2 signaling network, to discuss various approved methods for its detection in clinical specimens, and to describe the impressive results of therapies targeting HER2. Data Sources.-Selected literature searchable on PubMed as well as older studies revealed by the literature review were reviewed. Conclusion.-HER2 is an important member of a complex signaling network and when gene amplified, it results in an aggressive subtype of breast cancer. Patients with tumors found to overexpress HER2 protein or to be amplified for the gene are candidates for therapy that significantly reduces mortality. Source

Welte T.,Lester and Sue Smith Breast Center | Welte T.,Dan ncan Cancer Center | Welte T.,Cellular One | Welte T.,Diana Helis Henry Medical Research Foundation | And 7 more authors.
Journal of Mammary Gland Biology and Neoplasia | Year: 2015

In breast cancer, the most frequent site of metastasis is bone. Disseminated tumor cells (DTCs) can be detected in the bone marrow of patients by their expression of epithelial or oncogenic markers [1], and the presence and frequency of these DTCs are associated with poor prognosis. However, many of the details behind this process remain elusive, including the biological properties and fates of these apparently indolent cancer cells. To provide pre-clinical models of DTCs, we have developed a procedure that allows for controlled and enhanced delivery of tumor cells to the bone in animal experiments via injection into the iliac artery of the hind limb [2]. To our surprise, we found that most cancer cells became integrated into the solid bone matrix shortly after arriving in the bone, and only a minority can be flushed out with the bone marrow. Here we describe a method that helps to retrieve DTCs homing to the bone in which we achieve an improved recovery of those tumor cells closely associated with the bone microenvironment. In our view it is especially important to analyze these tumor cell subpopulations, as they may take full advantage of growth-, survival- and immune-protective signals provided by neighbor cells. We also show a pilot study on how this approach may be applied to the analysis of cancer dormancy. Our study suggests that the detection and retrieval of DTCs in clinical studies are incomplete because they are conducted exclusively with bone marrow aspirates. © 2015, Springer Science+Business Media New York. Source

Barone I.,Lester and Sue Smith Breast Center | Barone I.,University of Calabria | Brusco L.,Lester and Sue Smith Breast Center | Gu G.,Lester and Sue Smith Breast Center | And 10 more authors.
Journal of the National Cancer Institute | Year: 2011

BackgroundEstrogen receptor (ER) α is a successful therapeutic target in breast cancer, but patients eventually develop resistance to antiestrogens such as tamoxifen.MethodsTo identify genes whose expression was associated with the development of tamoxifen resistance and metastasis, we used microarrays to compare gene expression in four primary tumors from tamoxifen-treated patients whose breast cancers did not recur vs five metastatic tumors from patients whose cancers progressed during adjuvant tamoxifen treatment. Because Rho guanine dissociation inhibitor (GDI) α was underexpressed in the tamoxifen-resistant group, we stably transfected ERα-positive MCF-7 breast cancer cells with a plasmid encoding a short hairpin (sh) RNA to silence Rho GDIα expression. We used immunoblots and transcription assays to examine the role of Rho GDIα in ER-related signaling and growth of cells in vitro and as xenografts in treated nude mice (n = 8-9 per group) to examine the effects of Rho GDIα blockade on hormone responsiveness and metastatic behavior. The time to tumor tripling as the time in weeks from randomization to a threefold increase in total tumor volume over baseline was examined in treated mice. The associations of Rho GDIα and MTA2 levels with tamoxifen resistance were examined in microarray data from patients. All statistical tests were two-sided.ResultsRho GDIα was expressed at lower levels in ERα-positive tumors that recurred during tamoxifen treatment than in ERα-positive tamoxifen-sensitive primary tumors. MCF-7 breast cancer cells in which Rho GDIα expression had been silenced were tamoxifen-resistant, had increased Rho GTPase and p21-activated kinase 1 activity, increased phosphorylation of ERα at serine 305, and enhanced tamoxifen-induced ERα transcriptional activity compared with control cells. MCF-7 cells in which Rho GDIα expression was silenced metastasized with high frequency when grown as tumor xenografts. When mice were treated with estrogen or estrogen withdrawal, tripling times for xenografts from cells with Rho GDIα silencing were similar to those from vector-containing control cells; however, tripling times were statistically significantly faster than control when mice were treated with tamoxifen (median tripling time for tumors with Rho GDIα small interfering RNA = 2.34 weeks; for control tumors = not reached, hazard ratio = 4.13, 95% confidence interval = 1.07 to 15.96, P =. 040 [adjusted for multiple comparisons, P =. 119]). Levels of the metastasis-associated protein MTA2 were also increased upon Rho GDIα silencing, and combined Rho GDIα and MTA2 levels were associated with recurrence in 250 tamoxifen-treated patients.ConclusionLoss of Rho GDIα enhances metastasis and resistance to tamoxifen via effects on both ERα and MTA2 in models of ERα-positive breast cancer and in tumors of tamoxifen-treated patients. © 2011 The Author. Source

Litzenburger B.C.,Lester and Sue Smith Breast Center | Litzenburger B.C.,RWTH Aachen | Creighton C.J.,Baylor College of Medicine | Tsimelzon A.,Lester and Sue Smith Breast Center | And 17 more authors.
Clinical Cancer Research | Year: 2011

Purpose: We previously reported an insulin-like growth factor (IGF) gene expression signature, based on genes induced or repressed by IGF-I, which correlated with poor prognosis in breast cancer. We tested whether the IGF signature was affected by anti-IGF-I receptor (IGF-IR) inhibitors and whether the IGF signature correlated with response to a dual anti-IGF-IR/insulin receptor (InsR) inhibitor, BMS-754807. Experimental Design: An IGF gene expression signature was examined in human breast tumors and cell lines and changes were noted following treatment of cell lines or xenografts with anti-IGF-IR antibodies or tyrosine kinase inhibitors. Sensitivity of cells to BMS-754807 was correlated with levels of the IGF signature. Human primary tumorgrafts were analyzed for the IGF signature and IGF-IR levels and activity, and MC1 tumorgrafts were treated with BMS-754807 and chemotherapy. Results: The IGF gene expression signature was reversed in three different models (cancer cell lines or xenografts) treated with three different anti-IGF-IR therapies. The IGF signature was present in triplenegative breast cancers (TNBC) and TNBC cell lines, which were especially sensitive to BMS-754807, and sensitivity was significantly correlated to the expression of the IGF gene signature. The TNBC primary human tumorgraft MC1 showed high levels of both expression and activity of IGF-IR and IGF gene signature score. Treatment of MC1 with BMS-754807 showed growth inhibition and, in combination with docetaxel, tumor regression occurred until no tumor was palpable. Regression was associated with reduced proliferation, increased apoptosis, and mitotic catastrophe. Conclusions: These studies provide a clear biological rationale to test anti-IGF-IR/InsR therapy in combination with chemotherapy in patients with TNBC. © 2011 American Association for Cancer Research. Source

Hammerich-Hille S.,Lester and Sue Smith Breast Center | Kaipparettu B.A.,Lester and Sue Smith Breast Center | Tsimelzon A.,Lester and Sue Smith Breast Center | Creighton C.J.,Lester and Sue Smith Breast Center | And 6 more authors.
Journal of Biological Chemistry | Year: 2010

The scaffold attachment factors SAFB1 and SAFB2 are paralogs, which are involved in cell cycle regulation, apoptosis, differentiation, and stress response. They have been shown to function as estrogen receptor corepressors, and there is evidence for a role in breast tumorigenesis. To identify their endogenous target genes in MCF-7 breast cancer cells, we utilized a combined approach of chromatin immunoprecipitation (ChIP)-on-chip and gene expression array studies. By performing ChIP-on-chip on microarrays containing 24,000 promoters, we identified 541 SAFB1/SAFB2-binding sites in promoters of known genes, with significant enrichment on chromosomes 1 and 6. Gene expression analysis revealed that the majority of target genes were induced in the absence of SAFB1 or SAFB2 and less were repressed. Interestingly, there was no significant overlap between the genes identified by ChIP-on-chip and gene expression array analysis, suggesting regulation through regions outside the proximal promoters. In contrast to SAFB2, which shared most of its target genes with SAFB1, SAFB1 had many unique target genes, most of them involved in the regulation of the immune system.Asubsequent analysis of the estrogen treatment group revealed that 12% of estrogen-regulated genes were dependent on SAFB1, with the majority being estrogen-repressed genes. These were primarily genes involved in apoptosis, such as BBC3, NEDD9, and OPG. Thus, this study confirms the primary role of SAFB1/SAFB2 as corepressors and also uncovers a previously unknown role for SAFB1 in the regulation of immune genes and in estrogen-mediated repression of genes. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc. Source

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