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Hypermethylation of the Wilms' tumor suppressor gene CpG island in human breast carcinomas (1999)

Laux, Douglas E. ; Curran, Edward M. ; Welshons, Wade V. ; [et al.]

Springer

Breast cancer research and treatment 56 (1999), S. 35-43

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ISSN: 1573-7217

Keywords: breast cancer ; CpG island ; DNA hypermethylation ; Wilms' tumor suppressor gene

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract CpG island hypermethylation is known to be associated with transcriptional silencing of tumor suppressor genes in neoplasia. We have previously detected aberrantly methylated sites in the first intron of the Wilms' tumor suppressor (WT1) gene in breast cancer. In the present study, we extended the investigation to a CpG island located in the promoter and first exon regions of WT1. Methylation of this CpG island was found to be extensive in MCF‐7 and MDA‐MB‐231 breast cancer cells, as well as in 25% (five of 20 patients) of primary breast tumors. While levels of the known 3.0‐kb WT1 mRNAs were decreased or not detected in these cell lines, the expression could be partially restored following treatment with a demethylation agent, 5‐aza‐2′‐deoxycytidine. Surprisingly, a novel 2.5‐kb WT1 transcript was expressed at high levels in both untreated and treated MDA‐MB‐231 cells. This novel transcript was likely a WT1 variant missing the first exon, and therefore escaped the methylation control present in the normal transcript. Our study implicates the future need to investigate the significance of this aberrant transcript as well as the role of WT1 CpG island hypermethylation in breast neoplasia.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006222803788

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Lithium-stimulated proliferation and alteration of phosphoinositide metabolites in MCF-7 human breast cancer cells (1995)

Welshons, Wade V. ; Engler, Kathleen S. ; Taylor, Julia A. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Journal of Cellular Physiology 165 (1995), S. 134-144

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ISSN: 0021-9541

Keywords: Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Medicine

Notes: Lithium, which is used to treat bipolar psychiatric disorders, can stimulate proliferation of a number of cells in tissue culture. Proliferation of MCF-7 human breast cancer cells, which also respond to EGF and estrogens, was stimulated by LiCl (1-5 mM) within the concentration range that is encountered during human therapy with lithium. Stimulation of growth was specific for lithium; rubidium, potassium, and sodium showed no such effect. In the presence of antiestrogen, lithium stimulated the growth of hormone-dependent breast cancer cells MCF-7, ZR-75-1, and T47D but not hormone-independent MDA-MB-231 cells or an estrogen-independent clone of MCF-7 cells. Lithium-stimulated proliferation was limited by cytotoxicity which could be moderated by added potassium chloride (5-20 mM) in the medium. Each of the mitogens lithium, 17β-estradiol, and EGF increased the rate of uptake of myo-inositol into MCF-7 cells. Whether normalized to inositol lipids, to protein, or to DNA, steady-state levels of inositol phosphates were elevated by each of the mitogens including lithium, which inhibits the breakdown of inositol phosphates in the phosphoinositide signaling pathway. These data indicate that therapeutic concentrations of lithium can stimulate the proliferation of human breast cancer cells by a mechanism that may involve the phosphoinositide pathway. © 1995 Wiley-Liss Inc.

Additional Material: 8 Ill.