Environmental and Molecular Mutagenesis - Legacy Tobacco ...

147
SEMPERVIRINE : A NON-MUTAGENIC ANTI-TUMOR ALKALOID FROM GELSEMIUM
ELEGANS
Du,. .Y .-X .' Wu, Z .-L .', Liang, W .-Z .', Chen, H .-H .•, Liang, X .-Re•
Departments of Hygienee and Microblologye, Guangzhou Medical College,
195 Dongfeng Rd ., Guangzhou 510182, The People's Republic of China .
Gelsemium Elegans Benth, a medicinal herb grown in South China and
used locally as a roborans for pigs and sheeps, is seveNly toxic to
humans . Recently however, Sempervirine, an alkaloid extracted from
Gelsemiun elegans has shown promise as an anti- tumor agent in cancers
of the liver, esophagus and stomach . In this study we have examined
the in vitro effects of sempervirlne on tumor cell lines A-549,
PLC/PRF/2 and CNE-2 from lung, liver and nasopharynx respectively . At
drug concentrations between 100 to 400 yg/ml a significant decrease in
cell proliferation was observed for all three cell lines examined .
Whereas no effect was observed for in vitro mutagenicity assays using
bacterial strains TAs7, TAss, TAioo and TAio : at drug concentrations
between 2 to 500 Ng/ml in the presence or absence of a S-9 fraction .
Chromosome abberation assays with CHL cells exposed for 24 or 48 hours
at five drug concentrations between 5 to 100 pg/ml showed no difference
as compared to controls. The micronucleus test with NIH mice at
dosages of 1/2LDso, 1/5LDso and 1/10LDso showed no statistical
difference (P>0 .05) in the ratio of polychromatic erythrocytes to
normocytic erythrocytes as compared to controls .
148
TRAHSGENIC ANIMALS EXPRESSING THE BACTERIAL 06ALKYLGAUNINE-DNA ALKYLTRANSlERASE
GENE : A MODEL TO STUDY THE ROLE OF DNA REPAIR IN THE CARCINOGENBSIS OF N-NITROSO
COMPOUNDS. L .L . Dumenco, D .W . Clapp, I .K . Lim, S . Kesssn, C . Donovan, 3 . Warman,
N . Gorodetzkaya, J . Yun, T . Wagner, R .W . Hanson, S .L . Gerson . Ireland Cancer
Center, Dept of Biochem and Med, Cleveland, OH, 44106, and Edison Biotech Center
Ohio Univ Athens, OH, 457016
The DNA repair protein 0 alkylgaunine-DNA alkyltransferase is a critical
factor controlling tissue specific tumor induction following nitrosamine and
nitrosourea exposure in animals . We designed a chimerio gene consisting of 340 bp
of the promotor-regulatory region of the rat phosphoenolpyruvate carboxy kinass
(GTP) (PEPCK) gene linked to the ads gane coding for the ~~} alkyltransferase .
The PEPCK promotor is highly inducible in transganic animals by a high protein diet
or serotonin treatment and is primarily expressed in kldney and liver . Using this
chimeric gene, two haterozygous transgenic founder animals were obtained .
Offspring had two-fold increased alkyltransferasa activity in liver and kidney and
ada gene expression as confirmed by Northern analysis . The ~ gene was inducible
in the liver and kidney by a high protein diet and/or serotonin . ?olloving
induction, total alkyltransf.rase activity was increased five-fold above background
in liver and at least two-fold in kidne~r . These transgenic mice will allow us to
determine whether efficient repair of 0 alkylguanine-DNA adducts by high levels
of alkyltransferase activity can decrease the tissue specific carcinogenicity of
N-nitroso compounds .
149
EXPRESSION OF XRCC1 IN HUMAN TUMOR CELL LINES .
E . Dunphy, R .R . Weichselbaum, L .H . Thompson and J .L . Schwartz,
University of Chicago, Chicago, IL and Lawrence Livermore National
Laboratory, Livermore, CA (USA) .
XRCC1 is a gene whose expression complements the defect in the
mutagen-sensitive Chinese hamster cell line EM9 . The XRCC1 gene product
is believed to be involved in DNA single-strand break rejoining and SCE
induction . Absence of this gene product confers sensitivity to
ionizing radiation, monofunctional alkylating agents and halogenated
pyrimidines . In this study, the expression of XRCC1 was examined in a
variety of human tumor cell lines . These cell lines have widely
different radiosensitivities which might, in part, be a function of
xRCC1 expression . Twenty-five human squamous cell carcinomas and
sarcomas were examined . The radiosensitivities (DO) ranged from about
1 .0 Gy to 2 .7 Gy . The expression of XRCC1 was variable, being either
normal (compared to nontransformed fibroblasts) or somewhat elevated .
One cell line had a much reduced level of expression . There was no
relation between expression of XRCC1 and radiosensitivity nor-between
XRCC1 expression and the repair of DNA single-strand breaks (as
measured by DNA alkaline elution in a subset of the 25 tumor cell
lines) . Therefore, variations in the expression of XRCCl do not
underlie differences in human tumor radiosensitivity or the repair of
radiation-induced DNA damage . We are presently analyzing SCE frequency
and monofunctional alkylating agent sensitivity in these lines .
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
1989 EMS Abstracts 53
Notes