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Biomedical subjects

N D Zantek

Publications and source records attributed to N D Zantek.

6 recordsLinked to original sources

Equivalence of spray-dried K2EDTA, spray-dried K3EDTA, and liquid K3EDTA anticoagulated blood samples for routine blood center or transfusion service testing.

We compared the results of routine blood tests for 102 blood donors' samples and 100 patients' samples collected in spray-dried K2EDTA, spray-dried K3EDTA, and liquid K3EDTA blood collection tubes to evaluate the impact of changes in formulation of the anticoagulant (K2EDTA vs.K3EDTA), its application (liquid vs. spray-dried), and tube material (glass vs. plastic). Methods for ABO/D testing, antibody screening, and antibody identification included direct hemagglutination/microplate (Olympus(R) PK 7200) and gel column methods (Ortho ID-Micro Typing System/Gel Test). Additional studies on blood donors' samples included time delayed antigen testing and antibody identification and half-draw/half-evacuated collections. Also, we compared the results of routine ABO/D testing and antibody screening for 50 patients' samples collected in spray-dried K2EDTA and spray-dried K3EDTA and for an additional 50 patients' samples collected in spray-dried K2EDTA tubes from two different manufacturers. All patients' samples were tested in parallel by solid phase/microplate method (Immucor ABS 2000) and the standard manual tube method. All test results for routine blood bank tests on donors' and patients' samples were concordant, demonstrating the equivalence of spray-dried K2EDTA, spray-dried K3EDTA, and liquid K3EDTA blood collection tubes for routine donor center or transfusion service testing.

Journal Article↗

EphA2 overexpression causes tumorigenesis of mammary epithelial cells.

Elevated levels of protein tyrosine phosphorylation contribute to a malignant phenotype, although the tyrosine kinases that are responsible for this signaling remain largely unknown. Here we report increased levels of the EphA2 (ECK) protein tyrosine kinase in clinical specimens and cell models of breast cancer. We also show that EphA2 overexpression is sufficient to confer malignant transformation and tumorigenic potential on nontransformed (MCF-10A) mammary epithelial cells. The transforming capacity of EphA2 is related to the failure of EphA2 to interact with its cell-attached ligands. Interestingly, stimulation of EphA2 reverses the malignant growth and invasiveness of EphA2-transformed cells. Taken together, these results identify EphA2 as a powerful oncoprotein in breast cancer.

Animals↗

MCF-10A-NeoST: a new cell system for studying cell-ECM and cell-cell interactions in breast cancer.

PURPOSE: There is a continuing need for genetically matched cell systems to model cellular behaviors that are frequently observed in aggressive breast cancers. EXPERIMENTAL DESIGN: We report here the isolation and initial characterization of a spontaneously arising variant of MCF-10A cells, NeoST, which provides a new model to study cell adhesion and signal transduction in breast cancer. RESULTS: NeoST cells recapitulate important biological and biochemical features of metastatic breast cancer, including anchorage-independent growth, invasiveness in three-dimensional reconstituted membranes, loss of E-cadherin expression, and increased tyrosine kinase activity. A comprehensive analysis of tyrosine kinase expression revealed overexpression or functional activation of the Axl, FAK, and EphA2 tyrosine kinases in transformed MCF-10A cells. CONCLUSIONS: MCF-10A and these new derivatives provide a genetically matched model to study defects in cell adhesion and signaling that are relevant to cellular behaviors that often typify aggressive breast cancer cells.

Breast Neoplasms↗

E-cadherin regulates the function of the EphA2 receptor tyrosine kinase.

EphA2 is a member of the Eph family of receptor tyrosine kinases, which are increasingly understood to play critical roles in disease and development. We report here the regulation of EphA2 by E-cadherin. In nonneoplastic epithelia, EphA2 was tyrosine-phosphorylated and localized to sites of cell-cell contact. These properties required the proper expression and functioning of E-cadherin. In breast cancer cells that lack E-cadherin, the phosphotyrosine content of EphA2 was decreased, and EphA2 was redistributed into membrane ruffles. Expression of E-cadherin in metastatic cells restored a more normal pattern of EphA2 phosphorylation and localization. Activation of EphA2, either by E-cadherin expression or antibody-mediated aggregation, decreased cell-extracellular matrix adhesion and cell growth. Altogether, this demonstrates that EphA2 function is dependent on E-cadherin and suggests that loss of E-cadherin function may alter neoplastic cell growth and adhesion via effects on EphA2.

Breast Neoplasms↗