Frequency and molecular analysis of hprt mutations induced by estradiol inChinese hamster V79 cells

Citation
Ly. Kong et al., Frequency and molecular analysis of hprt mutations induced by estradiol inChinese hamster V79 cells, INT J ONCOL, 17(6), 2000, pp. 1141-1149
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Onconogenesis & Cancer Research
Journal title
INTERNATIONAL JOURNAL OF ONCOLOGY
ISSN journal
1019-6439 → ACNP
Volume
17
Issue
6
Year of publication
2000
Pages
1141 - 1149
Database
ISI
SICI code
1019-6439(200012)17:6<1141:FAMAOH>2.0.ZU;2-J
Abstract
The natural hormone estradiol (E-2) induces tumors in rodents and various t ypes of DNA damage in vitro, and in vivo, but has not been mutagenic in bac terial or mammalian assays. Recent reports of chromosomal and genetic lesio ns induced by E-2 has led us to re-examine the mutation frequency and molec ular alterations of the hypoxanthine-guanine phosphoribosyltransferase (hrp t) gene in Chinese hamster V79 cells. E-2 at both physiological and pharmac ological concentrations (10(-11), 10(-10), and 10(-7), 10(-6) M) significan tly increased the mutation frequency of the hrpt gene by 2.57-, 3.35-, 2.63 -, and 8.78-fold, respectively, compared to the controls, while 10(-13), 10 (-12), 10(-9), or 10(-8) M E-2 induced little change (less than or equal to 0.93-fold). PCR and a molecular analysis of the hprt coding sequence identi fied genetic lesions in the cDNA and/or genomic DNA in 15 of the 21 picked E-2-induced mutants (71%). Simple base substitutions, such as T-->G or T--> A transversions, were the most common mutations (8/21 or 38%) and frequentl y occurred at 122 bp or 407 bp of the hprt coding sequence. Deletion mutati ons were detected in 6 of the 21 clones (29%). An A-->G and a C-->T transit ion and a four-base insertion (TATT) were identified each in one mutant clo ne. A RT-PCR analysis demonstrated an abundant expression of the estrogen r eceptor-alpha (ER alpha). However, ICI 182,780, an antagonist of ERa, acted in an additive manner with E-2 and increased the hrpt mutation frequency. In conclusion, E-2 induces a low frequency of mutations (deletions and poin t mutations) in V79 cells, which is consistent with the weak carcinogenic a ctivity of this hormone. The mutagenic effects of E-2 in V79 cells are not mediated by the ER alpha..