Biomedical subjects

A K Godwin

Publications and source records attributed to A K Godwin.

77 records · Page 5Linked to original sources

PubMed1987

Regulation of a metallothionein-rasT24 fusion gene by zinc results in graded alterations in cell morphology and growth.

We constructed fusion genes consisting of the mouse metallothionein I (MT) 5' region and the coding region of either the human H-ras gene (c-rasP3) or a mutated allele (c-rasT24); both ras genes lacked the initial (non-coding) exon and the first 30 bp of the non-coding region of the second exon. Transfection of Rat-1 cells produced foci only with pMT-rasT24, and selection in soft agar yielded clones in which MT-rasT24 expression was zinc-regulatable. In response to increasing concentrations of ZnSO4, these lines showed increasingly altered morphology (conversion to fusiform or spheroidal morphology), progressively higher maximal cell density, and an increasingly greater fraction of cells in the S + G2 + M portion of the cell cycle at high density. MT-rasT24 RNA levels in zinc-responsive lines were increased between 4- and 6-fold by the addition of ZnSO4 (final concentration = 100 microM) to the medium. Replating cells in the absence of zinc reversed the biological effects and resulted in reduction in MT-rasT24 RNA levels. Thus, graded alterations in phenotype result from increasing levels of MT-rasT24 gene expression.

Animals↗

PubMed1985

Chemical carcinogens induce cadmium resistance and activate metallothionein genes in cadmium sensitive S49 mouse cells.

Treatment of cadmium-sensitive (Cds) metallothionein-negative S49 mouse cells with two direct-acting chemical carcinogens (N-ethylnitrosourea or N-acetoxy-2-acetylamino-fluorene) or with u.v. radiation induced a large increase in phenotypically stable cadmium-resistant (Cdr) variants. In contrast, treatment with any of three agents which alkylate proteins (N-ethylmaleimide, iodoacetate, or phenylmethyl-sulfonyl fluoride) was without effect. Similarly, treatment with 2-acetylaminofluorene (a pre-carcinogen) or with 12-O-tetradecanoylphorbol-13-acetate (a tumor promoter) did not result in an increase in Cdr variants. Initial studies indicate that in many variants the metallothionein-I gene, the metallothionein-II gene, or both have been activated. Thus the induction of cadmium resistance in Cds cells is a potentially useful system to explore the activation of quiescent genes by carcinogens.

Acetoxyacetylaminofluorene↗

PubMedDate not supplied

Genome scanning detects amplification of the cathepsin B gene (CtsB) in transformed rat ovarian surface epithelial cells.

OBJECTIVE: To isolate a portion of the amplicon inferred to be present in a malignant rat tumor cell line, NuTu 26, by the presence of a homogeneously staining chromosomal region (hsr) and identify genes embedded within it. METHODS: Genome scanning was used to identify an EcoRI fragment (8.6 kbp) within the amplified region of the NuTu 26 genome using a recently identified rat repetitive sequence, OST17 as a probe. The 8.6 kbp amplified fragment was sequenced and used as starting material to obtain additional sequence information by screening a P1 clone-derived DNA library to identify any genes likely embedded in the amplicon. Use of the microdissected hsr as a probe for fluorescence in situ hybridization (FISH) and application of Southern, Northern, and Western blot analysis confirmed the amplification of this region in the NuTu 26 genome. RESULTS: The cathepsin B gene was within the amplicon of the hsr-containing marker chromosome of NuTu 26. FISH analysis and chromosomal banding further revealed that the marker chromosome was a derivative of chromosomes 4 and 15, i.e., der(15)t(4;15). CONCLUSION: Cathepsin B gene amplification may contribute to some aspect of the biology of ovarian cancer. This concept is strengthened by the finding that the gene is overexpressed frequently in independently transformed rat ovarian surface epithelial cells.

Animals↗

PubMedDate not supplied

[Differential gene expression analysis by DNA microarrays technology and its application in molecular oncology].

Accumulation of genetic and epigenetic aberrations leads to malignant transformation of normal cells. Functional studies of cancer using genomic and proteomic tools will help to reveal the true complexity of the processes leading to cancer development in humans. Until recently, diagnosis and prognosis of cancer was based on conventional pathologic criteria and epidemiological evidence. Certain tumors were divided only into relatively broad histological and morphological subcategories. Rapidly developing methods of differential gene expression analysis promote the search for clinically relevant genes changing their expression levels during malignant transformation. DNA microarrays offer a unique possibility to rapidly assess the global expression picture of thousands genes in any given time point and compare the detailed combinatory analysis results of global expression profiles for normal and malignant cells at various functional stages or separate experimental conditions. Acquisition of such "genetic portraits" allows searching for regularity and difference in expression patterns of certain genes, understanding their function and pathological importance, and ultimately developing the "molecular nosology" of cancer. This review describes the basis of DNA microarray technology and methodology, and focuses on their applications in molecular classification of tumors, drug sensitivity and resistance studies, and identification of biological markers of cancer.

Biomarkers, Tumor↗

PubMedDate not supplied

Early ovarian cancer: a review of its genetic and biologic factors, detection, and treatment.

Early-stage ovarian carcinoma requires comprehensive surgical staging; reexploration for patients who had suboptimal initial surgery would indicate an apparent early ovarian carcinoma. After proper surgery, patients can be subdivided into a high- or low-risk group, and treatment options then can be discussed with the patient. Patients in the low-risk category can be followed up expectantly without any form of adjuvant therapy. Patients in the high-risk category, however, should be encouraged to participate in randomized clinical trials, because it is unclear at the current time which combination of chemotherapy and how many treatments should be used. A platinum-based paclitaxel regimen probably should be used, although the relative merits of carboplatin and cisplatin and the appropriate schedule for taxol (1 hour vs. 3 hours vs. 24 hours vs. 96 hours) are yet unknown. It is hoped that clinicians will continue to encourage patients to participate in randomized clinical trials so that optimal therapy for early ovarian cancer can be established.

Biomarkers, Tumor↗