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J Dirk Iglehart

Publications and source records attributed to J Dirk Iglehart.

12 recordsLinked to original sources
PubMed2006

Rapamycin inhibits proliferation of estrogen-receptor-positive breast cancer cells.

BACKGROUND: Estrogen-receptor (ER)-positive breast cancers comprise the majority of sporadic breast cancers. Although 50% respond to antihormonal treatment, both primary and acquired resistance limit the utility of this therapy, and other agents are needed. Rapamycin, an inhibitor of the mammalian Target of Rapamycin (mTOR), possesses antitumor activity against many tumors including breast tumors, and particularly against ER-positive breast cancer cell lines. The sensitivity of these cells to rapamycin has been attributed to activation of the PI3K/Akt/mTOR pathway by nongenomic ER signaling. The purpose of this study was to evaluate the efficacy of rapamycin against ER-positive breast cancer, particularly under 17beta-estradiol (E2)-dependent conditions, and to investigate mechanisms of rapamycin-sensitivity in ER-positive cells. MATERIALS AND METHODS: Breast cancer cell lines were tested for sensitivity to rapamycin. Antiproliferative effects of rapamycin, alone and in combination with tamoxifen, were assessed under E2-dependent conditions. Western blot analysis was used to detect activation of mTOR by nongenomic ER signaling. RESULTS: Rapamycin effectively inhibits proliferation of the ER-positive MCF-7 cell line. In our system, this sensitivity is probably not due to nongenomic ER activation of the PI3K/Akt/mTOR pathway; rapid stimulation of mTOR occurred nonspecifically after medium replacement, and addition of E2 stimulated mTOR only after 1 h. Combining rapamycin and tamoxifen under E2-dependent conditions yielded additive/synergistic effects at effective concentrations. CONCLUSIONS: These results suggest that rapamycin may be an effective treatment for ER-positive breast cancer, either alone or in combination with tamoxifen, and also may be a potential therapy for tamoxifen-resistant cancers.

Antibiotics, Antineoplastic↗
PubMed2006

Linkage between EGFR family receptors and nuclear factor kappaB (NF-kappaB) signaling in breast cancer.

In the United States there are 225,000 new cases of invasive breast cancer annually, and at least 50,000 women are diagnosed with ductal carcinoma in situ (DCIS). Breast cancer is a collection of disorders of mammary epithelial cells with distinct pathological characteristics and diverse clinical manifestations. Breast cancers are divided broadly into four classes by the level of the biomarkers HER2 (erbB2/neu) and the estrogen receptor (ER). Histologic grade is also an important modifier of breast cancer taxonomy and behavior. Broadly speaking, breast cancer can be divided into those that are HER2-positive, containing cancers that are both ER-positive and negative, cancers that are ER-positive and divided into high-grade and low-grade tumors, and the remaining but important class of cancers that are both ER-negative and HER2-negative. These last cancers are called basal-like and were first recognized as a distinct group by gene expression arrays. Nuclear factor kappaB (NF-kappaB) is family of multifunctional transcription factors that when activated generate pleotrophic changes in target cells. Elevated levels of active NF-kappaB are detected in many human diseases including breast cancers. High-level active NF-kappaB is detected in specific subclasses of breast cancers briefly described above, predominantly in ER-negative and epidermal growth factor family receptor (EGFR) overexpressing breast cancers (predominantly HER2 amplified cancers). This article is focused on the role of NF-kappaB activation initiated by the EGFR family receptors in subclasses of breast cancer. The combined influence of EGFR family receptors and NF-kappaB signaling on the transformation of ER-negative human mammary epithelial cell is illustrated.

Animals↗
PubMed2006

X chromosomal abnormalities in basal-like human breast cancer.

Sporadic basal-like cancers (BLC) are a distinct class of human breast cancers that are phenotypically similar to BRCA1-associated cancers. Like BRCA1-deficient tumors, most BLC lack markers of a normal inactive X chromosome (Xi). Duplication of the active X chromosome and loss of Xi characterized almost half of BLC cases tested. Others contained biparental but nonheterochromatinized X chromosomes or gains of X chromosomal DNA. These abnormalities did not lead to a global increase in X chromosome transcription but were associated with overexpression of a small subset of X chromosomal genes. Other, equally aneuploid, but non-BLC rarely displayed these X chromosome abnormalities. These results suggest that X chromosome abnormalities contribute to the pathogenesis of BLC, both inherited and sporadic.

Alleles↗
PubMed2006

Declining plasma fibrinogen alpha fragment identifies HER2-positive breast cancer patients and reverts to normal levels after surgery.

Breast cancer is the most common nonskin malignancy affecting women. Currently, no simple, blood-based diagnostic test exists to complement radiological screening and increase sensitivity of detection. To screen plasma specimens and identify biomarkers that detect HER2-positive breast cancer, automated robotic sample processing followed by surface-enhanced laser desorption ionization time-of-flight (SELDI-TOF) mass spectroscopy was used. Multiple statistical algorithms were used to select biomarkers that segregate cancer patients versus controls and produced average CV rates ranging from 20% to 29%. A set of seven biomarkers were validated on an independent test data set and achieved the best error rate of 19.1%. A permutation test indicated a p-value for CV error less than 0.002. Moreover, a ROC curve using these biomarkers achieved an area-under-the-curve value of 0.95 on an independent test data set. The marker responsible for most of the resolving power was identified as a fragment of Fibrinogen Alpha (FGA) encompassing residues 605-629. This marker was present at lower levels in cancer patients as compared to controls. The importance of this biomarker was validated in a longitudinal study comparing pre- and post-operative levels and was shown to revert to normal levels after surgery. This fragment may serve as a useful diagnostic and treatment-monitoring marker.

Amino Acid Sequence↗
PubMed2005

Crossroads of estrogen receptor and NF-kappaB signaling.

Cellular homeostasis in higher organisms is maintained by balancing cell growth, differentiation, and death. Two important systems that transmit extracellular signals into the machinery of the cell nucleus are the signaling pathways that activate nuclear factor kappaB (NF-kappaB) and estrogen receptor (ER). These two transcription factors induce expression of genes that control cell fates, including proliferation and cell death (apoptosis). However, ER has anti-inflammatory effects, whereas activated NF-kappaB initiates and maintains cellular inflammatory responses. Recent investigations elucidated a nonclassical and nongenomic effect of ER: inhibition of NF-kappaB activation and the inflammatory response. In breast cancer, antiestrogen therapy might cause reactivation of NF-kappaB, potentially rerouting a proliferative signal to breast cancer cells and contributing to hormone resistance. Thus, ER ligands that selectively block NF-kappaB activation could provide specific potential therapy for hormone-resistant ER-positive breast cancers.

Animals↗
PubMed2005

Gene expression profiling of NMU-induced rat mammary tumors: cross species comparison with human breast cancer.

Breast cancer is a complex genetic disease characterized by the accumulation of multiple molecular alterations. The NMU breast cancer model induced in the rat is used for the study of mammary carcinogenesis because it closely mimics human breast disease. To assess the validity of this model from a more global molecular perspective, and also to devise a general technique to compare animal profiles with human microarray studies, we have characterized 25 NMU-induced mammary tumors and 11 normal glands using a combination of immunohistochemical and microarray analyses. The rat mammary carcinomas were classified as non-invasive, ER-positive ductal carcinomas with a composition of differentiated epithelial and myoepithelial cell lineages. Gene expression profiles generated using rat Affymetrix arrays containing 15,866 genes demonstrated that the rat mammary tumors are homogeneous and that H-ras mutations did not confer a unique molecular signature. We compared the resulting rat profiles with those obtained from a human dataset by merging the raw microarray data, using an approach that involves a combination of cross-species and cross-platform analysis. Using this novel strategy, we demonstrate the ability of 2305 rat orthologs to recapitulate the classification of human tumors derived from human Affymetrix arrays. The gene expression profiles of the NMU-induced primary tumors were most similar to ER-positive, low to intermediate grade breast cancer. Our technique provides a means to correlate gene expression data from animal models of cancer to human cancer and disease states.

Animals↗
PubMed2005

BRCA1 promoter methylation in sporadic breast tumors: relationship to gene expression profiles.

BRCA1 is a tumor suppressor gene that functions in DNA repair. Basal-like tumors are a distinctive subtype of breast cancer defined by gene expression profiles. Hereditary BRCA1 breast tumors and basal-like sporadic tumors have a similar phenotype and gene expression signature, suggesting involvement of BRCA1 in the pathogenesis of sporadic basal-like cancer. This study evaluates the role of BRCA1 in sporadic breast tumorigenesis. BRCA1 protein expression and promoter methylation are compared to tumor histopathology and gene expression profiles. We find BRCA1 protein expression correlates with tumor mitotic rate, consistent with normal cell-cycle regulation of the BRCA1 gene. Methylation is found in 21% of tumors and is associated with lower BRCA1 protein, but not with specific pathologic features. Basal-like tumors, defined by hierarchical clustering of gene expression, have infrequent BRCA1 methylation and high levels of BRCA1 protein expression consistent with their high mitotic rate. Tumors with BRCA1 promoter methylation are present in all expression clusters; however, a subgroup of ER-positive high-grade tumors has a significantly greater number of BRCA1 methylated tumors. Absence of BRCA1 promoter methylation and high levels of BRCA1 expression in basal-like sporadic tumors suggest alternate explanations for the phenotypic similarities of these tumors to hereditary BRCA1 tumors.

Breast Neoplasms↗
PubMed2004

NF-kappa B activation in human breast cancer specimens and its role in cell proliferation and apoptosis.

Lack of molecular targets in estrogen receptor-negative (ER-negative) breast cancer is a major therapeutic hurdle. We studied NF-kappa B activation in human breast tumors and in carcinoma cell lines. Activated NF-kappa B was detected predominantly in ER-negative vs. ER-positive breast tumors and mostly in ER-negative and ErbB2-positive tumors (86%). These in vivo results demonstrate association of activated NF-kappa B with a subgroup of human breast tumors and are consistent with previously reported in vitro observations using similar classes of human breast cancer cell lines. Finding such an association suggested functional and biological significance. Immunofluorescence demonstrated increased nuclear p65, a component of the active NF-kappa B complex, in cytokeratin 19 (CK19)-positive epithelial cells of ER-negative/ErbB2-positive tumor samples. In contrast, nuclear NF-kappa B was detected mostly in stroma of ER-negative and ErbB2-negative tumors, suggesting a role of activated NF-kappa B in intercellular signaling between epithelial and stromal cells in this type of breast cancers. To elucidate roles of activated NF-kappa B, we used an ER-negative and ErbB2-positive human breast tumor cell line (SKBr3). The polypeptide heregulin beta1 stimulated, and herceptin, the anti-ErbB2 antibody, inhibited, NF-kappa B activation in SKBr3 cells. The NF-kappa B essential modulator (NEMO)-binding domain (NBD) peptide, an established selective inhibitor of I kappa B-kinase (IKK), blocked heregulin-mediated activation of NF-kappa B and cell proliferation, and simultaneously induced apoptosis only in proliferating and not resting cells. These results substantiate the hypothesis that certain breast cancer cells rely on NF-kappa B for aberrant cell proliferation and simultaneously avoid apoptosis, thus implicating activated NF-kappa B as a therapeutic target for distinctive subclasses of ER-negative breast cancers.

Amino Acid Sequence↗
PubMed2002

Rate-limiting effects of Cyclin D1 in transformation by ErbB2 predicts synergy between herceptin and flavopiridol.

Cyclin D1 is downstream of erbB2 and is required for erbB2 transformation. Here we report thatcyclin D1 functions are essential, rate limiting for erbB2 transformation, and reciprocally increase erbB2 levels. This interaction depends on three cyclin D1 activities: cyclin-dependent kinase 4-dependent kinase activity, titration of p27, and an intrinsic transcriptional activity of cyclin D1. Drugs active against erbB2 and cyclin D1 (Herceptin and flavopiridol) were synergistically cytotoxic against erbB2-positive breast cancer cell lines. Addition of flavopiridol to Herceptin synergistically lowered erbB2 levels in these cells. Our data suggest the potential use of combinations of cyclin-dependent kinase inhibitors and Herceptin in breast cancer.

3T3 Cells↗
PubMed2002

Pre-counseling education materials for BRCA testing: does tailoring make a difference?

Although tailored print materials (TPMs) have been assessed for a variety of behavioral targets, their effectiveness as decision aids for genetic testing had not been evaluated at the time this study began. We compared TPMs and non-tailored print material (NPMs) that included similar content about genetic testing for breast and ovarian cancer susceptibility. TPMs were prepared especially for an individual based on information from and about her. We mailed baseline surveys to 461 women referred by physicians or identified through a tumor registry. All had personal and family histories of breast and/or ovarian cancer and, on the basis of these histories, an estimated > or =10% probability of carrying a mutation in the breast/ovarian cancer genes BRCA1 or BRCA2. The 325 (70%) who responded were randomly assigned to receive TPM or NPM. Followup surveys, mailed 2 weeks following receipt of print materials, were returned by 262 women (81% of baseline responders). Participants were predominately white (94%) and well-educated (50% college graduates). The mean age was 49 years. At follow-up, TPM recipients exhibited significantly greater improvement in percent of correct responses for the 13-item true/false measure of knowledge (24% increase for TPM vs. 16% for NPM; p < 0.0001) and significantly less over-estimation of risk of being a mutation carrier (40% TPM group overestimated vs. 70% NPM; p < 0.0001). Anxiety did not differ significantly between groups. Reactions to materials differed on two items: "seemed to be prepared just for me" (76% TPM vs. 52% NPM; p < 0.001) and "told me what I wanted to know about BRCA1 and 2 testing" (98% TPM vs. 91% NPM; p < 0.05). TPMs showed an advantage in increasing knowledge and enhancing accuracy of perceived risk. Both are critical components of informed decision making.

Adult↗
PubMedDate not supplied

Attitudes, knowledge, risk perceptions and decision-making among women with breast and/or ovarian cancer considering testing for BRCA1 and BRCA2 and their spouses.

A limited number of studies have examined the involvement of spouses in the decision-making process for genetic testing as well as impact of the actual testing. This report presents data from 40 women with a personal history of breast and/or ovarian cancer who were considering genetic testing for BRCA1 and BRCA2 and their spouses. We examined knowledge and attitudes regarding genetic testing for breast cancer susceptibility, perceptions of the likelihood that their wives (the women) had a BRCA1 or BRCA2 mutation, pros and cons of genetic testing, spouses' satisfaction with their involvement in the decision-making process and additional resources they would find helpful. Knowledge about cancer genetics and genetic testing for BRCA1 and BCA2 was limited among both women and their spouses. Up to one-third of spouses indicated that they would like to avail themselves of additional sources of information about BRCA1 and BRCA2 testing. Most spouses indicated that they thought their wives had a mutation in BRCA1 or BRCA2 and that their wives' breast cancers would recur. Pros of genetic testing were emphasized more than cons among both parties. Overall, spouses were satisfied with their role in the decision-making process. Future interventions to improve the decision-making process regarding genetic testing for breast cancer susceptibility should be undertaken.

ATP Binding Cassette Transporter, Subfamily G, Mem↗