Modulation of the cytotoxicity of 3'-azido-3'-deoxythymidine and methotrexate after transduction of folate receptor cDNA into human cervical carcinoma: identification of a correlation between folate receptor expression and thymidine kinase activity.

Important note: Information in this article was accurate in 1999. The state of the art may have changed since the publication date.

Cancer Res. 1999 Feb 15;59(4):940-6. Unique Identifier : AIDSLINE MED/99151546
Sun XL; Jayaram HN; Gharehbaghi K; Li QJ; Xiao X; Antony AC; Department of Medicine, Indiana University School of Medicine,; Indianapolis 46202, USA.

Abstract: Cervical carcinoma is an AIDS-defining illness. The expression of folate receptors (FRs) in cervical carcinoma (HeLa-IU1) cells was modulated by stable transduction of FR cDNA encapsidated in recombinant adeno-associated virus-2 in the sense and antisense orientation (sense and antisense cells, respectively). Although sense cells proliferated slower than antisense or untransduced cells in vivo and in vitro in 2% (but not 10%) FCS, [methyl-3H]thymidine incorporation into DNA was significantly increased in sense cells in 10% serum; therefore, the basis for this discrepancy was investigated. The activity of thymidine kinase (TK) was subsequently directly correlated with the extent of FR expression in single cell-derived clones of transduced cells. This elevated TK activity was not a result of recruitment of the salvage pathway based on the presence of adequate dTTP pools, normal thymidylate synthase (TS) activity, persistence of increased thymidine incorporation despite the exogenous provision of excess 5,10-methylene-tetrahydrofolate, and documentation of adequate folates in sense cells. The increase in TK activity conferred significant biological properties to sense cells (but not antisense or untransduced cells) as demonstrated by augmented phosphorylation of 3'-azido-3'-deoxythymidine (AZT) and concomitantly greater sensitivity to the cytotoxic effects of AZT. Conversely, sense cells were highly resistant to methotrexate, but this was reversed by the addition of AZT. The direct correlation of FR expression and TK activity indicates a previously unrecognized consequence of FR overexpression.

Keywords: JOURNAL ARTICLE Antimetabolites, Antineoplastic/*PHARMACOLOGY Carrier Proteins/ANALYSIS/*GENETICS Cervix Neoplasms/*DRUG THERAPY/METABOLISM Drug Resistance, Neoplasm Female *Gene Transfer Human Methotrexate/*PHARMACOLOGY Support, Non-U.S. Gov't Support, U.S. Gov't, Non-P.H.S. Support, U.S. Gov't, P.H.S. Thymidine/METABOLISM Thymidine Kinase/*METABOLISM Zidovudine/*PHARMACOLOGY
990530
A9950918

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