Promotion of breast cancer by β-Hexachlorocyclohexane in MCF10AT1 cells and MMTV-neu mice

<p>Abstract</p> <p>Background</p> <p>Exposure to β-Hexachlorocyclohexane (β-HCH), a contaminant of the hexachlorohexane pesticide lindane, has been implicated as a risk factor in the development of breast cancers in epidemiological studies. Previous studies in our laboratory have demonstrated the ability of β-HCH to elicit its actions via a ligand-independent activation of the estrogen receptor through increased c-Neu (= erbB₂or HER-2) expression and kinase activation in both the BG-1 and MCF-7 cell lines. In addition, long term exposure (33 passages) to β-HCH was shown to promote the selection of MCF-7 cells which exhibit a more metastatic phenotype.</p> <p>Methods</p> <p>In this current study, we decided to investigate the long-term effects of β-HCH in both the MCF10AT1 cell line which was derived from a normal epithelial cell line by stably transfecting a mutated c-Ha-ras and a MMTV-Neu mouse model for mammary cancer <it>in vivo</it>. MCF10AT1 cells were exposed for 20 passages with β-HCH, 4-OH-Tamoxifen (Tam), or 17-β-estradiol (E₂) after which cells were analyzed for proliferation rates and mRNA expression by RT-PCR. In our <it>in vivo </it>studies, MMTV-Neu mice were injected with β-HCH and observed for tumor formation over a 70 week period.</p> <p>Results</p> <p>β-HCH and Tam selected MCF10AT1 cells demonstrated increased mRNA expression of MMP-13 (collagenase-3) a marker of increased invasiveness. β-HCH treatment was also seen to increase the expression in a number of proto-oncogenes (c-Neu, Cyclin D1, p27), cell status markers (Met-1, CK19), and the inflammatory marker NFκB. Previous studies, have demonstrated the role of these markers as evidence of malignant transformations, and further illustrate the ability of β-HCH to be carcinogenic. To demonstrate β-HCH's tumorigenic properties in an <it>in vivo </it>system, we used an MMTV-Neu mouse model.</p> <p>MMTV-Neu is a c-Neu overexpressing strain which has been shown to spontaneously develop mammary tumors at later stages of aging. In this experiment, β-HCH exposure was shown to both accelerate the appearance (~8 weeks for median tumor-free period) and incidence (~25% increase at the end of the test period) of tumors when compared to control mice receiving only the corn-oil vehicle.</p> <p>Conclusion</p> <p>Based upon these results, it was concluded that β-HCH does act as a breast cancer promoter which exerts its tumorigenic activity via increased c-Neu expression.</p

Universal phase transitions of B1 structured stoichiometric transition-metal carbides

The high-pressure phase transitions of B1-structured stoichiometric transition metal carbides (TMCs, TM=Ti, Zr, Hf, V, Nb, and Ta) were systematically investigated using ab initio calculations. These carbides underwent universal phase transitions along two novel phase-transition routes, namely, B1\rightarrowdistorted TlI (TlI')\rightarrowTlI and/or B1\rightarrowdistorted TiB (TiB')\rightarrowTiB, when subjected to pressures. The two routes can coexist possibly because of the tiny enthalpy differences between the new phases under corresponding pressures. Four new phases result from atomic slips of the B1-structured parent phases under pressure. After completely releasing the pressure, taking TiC as a representative of TMCs, only its new TlI'-type phase is mechanically and dynamically stable, and may be recovered.Comment: [email protected]

Role of axillary sentinel lymph node biopsy in patients with pure ductal carcinoma in situ of the breast

BACKGROUND: Sentinel lymph node (SLN) biopsy is an effective tool for axillary staging in patients with invasive breast cancer. This procedure has been recently proposed as part of the treatment for patients with ductal carcinoma in situ (DCIS), because cases of undetected invasive foci and nodal metastases occasionally occur. However, the indications for SLN biopsy in DCIS patients are controversial. The aim of the present study was therefore to assess the incidence of SLN metastases in a series of patients with a diagnosis of pure DCIS. METHODS: A retrospective evaluation was made of a series of 102 patients who underwent SLN biopsy, and had a final histologic diagnosis of pure DCIS. Patients with microinvasion were excluded from the analysis. The patients were operated on in five Institutions between 1999 and 2004. Subdermal or subareolar injection of 30–50 MBq of 99 m-Tc colloidal albumin was used for SLN identification. All sentinel nodes were evaluated with serial sectioning, haematoxylin and eosin staining, and immunohistochemical analysis for cytocheratin. RESULTS: Only one patient (0.98%) was SLN positive. The primary tumour was a small micropapillary intermediate-grade DCIS and the SLN harboured a micrometastasis. At pathologic revision of the specimen, no detectable focus of microinvasion was found. CONCLUSION: Our findings indicate that SLN metastases in pure DCIS are a very rare occurrence. SLN biopsy should not therefore be routinely performed in patients who undergo resection for DCIS. SLN mapping can be performed, as a second operation, in cases in which an invasive component is identified in the specimen. Only DCIS patients who require a mastectomy should have SLN biopsy performed at the time of breast operation, since in these cases subsequent node mapping is not feasible

Pretreatment Serum Concentrations of 25-Hydroxyvitamin D and Breast Cancer Prognostic Characteristics: A Case-Control and a Case-Series Study

Results from epidemiologic studies on the relationship between vitamin D and breast cancer risk are inconclusive. It is possible that vitamin D may be effective in reducing risk only of specific subtypes due to disease heterogeneity.In case-control and case-series analyses, we examined serum concentrations of 25-hydroxyvitamin D (25OHD) in relation to breast cancer prognostic characteristics, including histologic grade, estrogen receptor (ER), and molecular subtypes defined by ER, progesterone receptor (PR) and HER2, among 579 women with incident breast cancer and 574 controls matched on age and time of blood draw enrolled in the Roswell Park Cancer Institute from 2003 to 2008. We found that breast cancer cases had significantly lower 25OHD concentrations than controls (adjusted mean, 22.8 versus 26.2 ng/mL, p<0.001). Among premenopausal women, 25OHD concentrations were lower in those with high- versus low-grade tumors, and ER negative versus ER positive tumors (p≤0.03). Levels were lowest among women with triple-negative cancer (17.5 ng/mL), significantly different from those with luminal A cancer (24.5 ng/mL, p = 0.002). In case-control analyses, premenopausal women with 25OHD concentrations above the median had significantly lower odds of having triple-negative cancer (OR = 0.21, 95% CI = 0.08-0.53) than those with levels below the median; and every 10 ng/mL increase in serum 25OHD concentrations was associated with a 64% lower odds of having triple-negative cancer (OR = 0.36, 95% CI = 0.22-0.56). The differential associations by tumor subtypes among premenopausal women were confirmed in case-series analyses.In our analyses, higher serum levels of 25OHD were associated with reduced risk of breast cancer, with associations strongest for high grade, ER negative or triple negative cancers in premenopausal women. With further confirmation in large prospective studies, these findings could warrant vitamin D supplementation for reducing breast cancer risk, particularly those with poor prognostic characteristics among premenopausal women

Dkk4 and Eda Regulate Distinctive Developmental Mechanisms for Subtypes of Mouse Hair

The mouse hair coat comprises protective “primary” and thermo-regulatory “secondary” hairs. Primary hair formation is ectodysplasin (Eda) dependent, but it has been puzzling that Tabby (Eda-/y) mice still make secondary hair. We report that Dickkopf 4 (Dkk4), a Wnt antagonist, affects an auxiliary pathway for Eda-independent development of secondary hair. A Dkk4 transgene in wild-type mice had no effect on primary hair, but secondary hairs were severely malformed. Dkk4 action on secondary hair was further demonstrated when the transgene was introduced into Tabby mice: the usual secondary follicle induction was completely blocked. The Dkk4-regulated secondary hair pathway, like the Eda-dependent primary hair pathway, is further mediated by selective activation of Shh. The results thus reveal two complex molecular pathways that distinctly regulate subtype-based morphogenesis of hair follicles, and provide a resolution for the longstanding puzzle of hair formation in Tabby mice lacking Eda

Rescue of heterochromatin organization in Hutchinson-Gilford progeria by drug treatment

Hutchinson-Gilford progeria (HGPS) is a premature aging syndrome associated with LMNA mutations. Progeria cells bearing the G608G LMNA mutation are characterized by accumulation of a mutated lamin A precursor (progerin), nuclear dysmorphism and chromatin disorganization. In cultured HGPS fibroblasts, we found worsening of the cellular phenotype with patient age, mainly consisting of increased nuclear-shape abnormalities, progerin accumulation and heterochromatin loss. Moreover, transcript distribution was altered in HGPS nuclei, as determined by different techniques. In the attempt to improve the cellular phenotype, we applied treatment with drugs either affecting protein farnesylation or chromatin arrangement. Our results show that the combined treatment with mevinolin and the histone deacetylase inhibitor trichostatin A dramatically lowers progerin levels, leading to rescue of heterochromatin organization and reorganization of transcripts in HGPS fibroblasts. These results suggest that morpho-functional defects of HGPS nuclei are directly related to progerin accumulation and can be rectified by drug treatment

Case-Control Study of Vitamin D, dickkopf homolog 1 (DKK1) Gene Methylation, VDR Gene Polymorphism and the Risk of Colon Adenoma in African Americans

There are sparse data on genetic, epigenetic and vitamin D exposure in African Americans (AA) with colon polyp. Consequently, we evaluated serum 25(OH) D levels, vitamin D receptor (VDR) polymorphisms and the methylation status of the tumor suppressor gene dickkopf homolog 1 (DKK1) as risk factors for colon polyp in this population.The case-control study consisted of 93 patients with colon polyp (cases) and 187 healthy individuals (controls) at Howard University Hospital. Serum levels of 25(OH)D (including D3, D2, and total) were measured by liquid chromatography-mass spectrometry. DNA analysis focused on 49 single nucleotide polymorphisms (SNPs) in the VDR gene. Promoter methylation analysis of DKK1 was also performed. The resulting data were processed in unadjusted and multivariable logistic regression analyses.Cases and controls differed in vitamin D status (D(3)<50 nmol/L: Median of 35.5 in cases vs. 36.8 in controls nmol/L; P = 0.05). Low levels of 25(OH)D(3) (<50 nmol/L) were observed in 86% of cases and 68% of controls and it was associated with higher risks of colon polyp (odds ratio of 2.7, 95% confidence interval 1.3-3.4). The SNP analysis showed no association between 46 VDR polymorphisms and colon polyp. The promoter of the DKK1 gene was unmethylated in 96% of the samples.We found an inverse association between serum 25(OH)D(3) and colon polyp in AAs. VDR SNPs and DKK1 methylation were not associated with colon polyp. Vitamin D levels may in part explain the higher incidence of polyp in AAs

MMP19 Is Essential for T Cell Development and T Cell-Mediated Cutaneous Immune Responses

Matrix metalloproteinase-19 (MMP19) affects cell proliferation, adhesion, and migration in vitro but its physiological role in vivo is poorly understood. To determine the function of MMP19, we generated mice deficient for MMP19 by disrupting the catalytic domain of mmp19 gene. Although MMP19-deficient mice do not show overt developmental and morphological abnormalities they display a distinct physiological phenotype. In a model of contact hypersensitivity (CHS) MMP19-deficient mice showed impaired T cell-mediated immune reaction that was characterized by limited influx of inflammatory cells, low proliferation of keratinocytes, and reduced number of activated CD8+ T cells in draining lymph nodes. In the inflamed tissue, the low number of CD8+ T cells in MMP19-deficient mice correlated with low amounts of proinflammatory cytokines, especially lymphotactin and interferon-inducible T cell α chemoattractant (I-TAC). Further analyses showed that T cell populations in the blood of immature, unsensitized mice were diminished and that this alteration originated from an altered maturation of thymocytes. In the thymus, thymocytes exhibited low proliferation rates and the number of CD4+CD8+ double-positive cells was remarkably augmented. Based on the phenotype of MMP19-deficient mice we propose that MMP19 is an important factor in cutaneous immune responses and influences the development of T cells