Environmental and Molecular Mutagenesis - Legacy Tobacco ...

162 1989 EMS Abstracts
http://legacy.library.ucsf.edu/tid/clb93d00/pdf
NOtES'- "-'"'fionship-bgt_t+e~he genotoxicity and carcinogenicity of the same cytotoxic
agents . The model for this purpose has been the thorough literature
surve' oLt herapy induced leukemias during the period from 1930
to 1988 . Over 130_o secondary acute leukemias are included . It is established
that the cytostatic compounds with strong BCE induction formed
the basis off the chemotherapy of more than 9d1i of all the primary malignancies
, which were later followed by an acute leukemia of the induced
type . On the contrary, only a few secondary leukemias were repotked
after the administration of an " 8CE negative " cytostatic treatment
schedule . This observation supports the conclusion t at the BCE assay
is a good indicator of the genotoxicity and carcinogenicity of different
cytostatic agents, and as such it can reasonably be used in planing
new therapeutical trials with low leukemogenic activity but also
high clinical efficacy, in malignancies which have a high probability
for cure .
470
NfIATIOYAL SPEY:IFIJITY OF 2-(:YANJE'D(YtZNE 07QDE IN HIlMN LV1PfOB[ .ASA)ID CELLS . L . Redo, D. Slspson, J .
Cochrane, VLiber and T.R. Sknpak . Chmdcal IMustry Institute of Toxicology . Research Triangle Park, NC
(USA) and `liatvatd School of Public Health, Boston, ?U (USA)
The proposed sutagenic metabolite of the rat carcirogee acrylanitrile, 2-cyanethylene oxide (AND), is
nutaganic at both the hunan tk and prt loci . To develop a better urdeistanding of its or:clanism of action
in human cella, our grcup has determined the specific It(A sequsnce alterations irdueed by ANJ treataent .
Analysis of several tk-/- and lrt- mutants by Southern blot liybridisaticn shawed that sost of the iMuced
mutants had no detectable alterations . A collection of brt- mutaixs were further characterized by dideoery
sequercing of cloned 1rt cINA . Point mutatiare in the lct codin6 region Wore obsetved in 9 of 17 lrtautants
; 5 accua-ced at AT base pairs and 4 at OC base pairs . 8/17 ct- mutarxs displayed aberrant splicing
of trt mRNA, resulting in the loss of single and maltiple ebxm, as tiiall as alternative splicing at a
cryptic splice site vithin aeon 9 . Southern blot analysis of aitants wdth single axmn losses revealed no
visible alterations . Analysis of one mutaix missing afmas 3-6 in its sRNA did reveal a visible deletion in
its gecnodc 1NA. The intron/exon jurcticns of three aitanta (one sd,th somn 7 loss, one adth exan 8 loss,
and one mutant exhibdting cryptic splicing in e:mn 9) tiere PCR aplified fram gemedc INA and analyzed by
Southern blot using ema-specific probes . The amos missing ftcm the rt aRNA were present in the $enomdc
rt aequence . The pertinent intton/exoa regions of l,xt genosd .c INA fram a nRant rdth axon 8 loss and a
mrtant exhibiting cryptic splicing in a:mn 9 uare cloned into M13op19 and sequenced . Point sutations in the
conceneus splice acceptor site of ewon 8(AT+fA) ard cmn 9(ATKiC) were observed . These observations
indicate that AND icduces primarily point .utations in hmmn cells at both AT and OC base pairs, and that
concensus splice acceptor sites are prone to ®rtageneeis . This wrk also suggests that there are at least
two pramutagentc lesions irduced by AA1) .
471
MOLECULAR ANALYSIS OF HPRT- T-LYMPHOCYTES DERIVED FROM AN IN VIVO CLONAL
AMPLIFNATION . L . Recio, D . Simpson, J . Cochrane, T . Skopek, J .A . Nicklaaa, J .P .
O'Neill , and R .J . Albertinia) . Chemical Industry Institute of Toxicology, RTP . NC
(USA) and the aUniversity of Vermont, Burlington, VT (USA) .
T-lymphocytes rearrange their T-cell receptor (TCR) genes during differentiation
in the thymus and then pass the unique TCR gene patterns to their clonal descendents .
Analysis of TCR gene rearrangements has been used to establish the clonal relationship
of hprt- T-lymphocytes isolated from the peripheral blood of humans (Mutagenesis
2 :341) . A female subject has been identified with an extremely high and increasing
frequency of 6-thioguanine-resistant T-lymphocytes . The majority (>92X) of these
mutants display the same TCR pattern and therefore must be sibs (Environ . Mol . Hutat .
12 :271) . To develop a better understanding of the genesis of these mutants we have
isolated and sequenced hprt cDNA from 15 mutant clones displaying the same TCR
pattern . All 15 mutants were missing exon 6 from the hcrt message, suggesting that
this mutation was an early event during the clonal expansion process . One mutant was
also missing axon 8 in addition to exon 6 . These results demonstrate that clonal
expansion of mutants in vivo can seriously affect both the frequency and spectrum of
hprt- mutants observed 1n vivo . The preliminary finding of one mutant possessing two
separate alterations also suggests the possibility of extreme genetic instability in
this population of dividing T-lymphocytes .
POSITIVE CORRELATION BETWEEN SISTER CHROHATLD KXCHANCB AND COTININf! IN SMOKERS
Reidy, J .A ., Chen . A .T .L ., Spiorto, F .W ., Waymack, P .P ., Jr ., and Smith, S .J .
Division of Environmental Health Laboratory Sciences . Center for Rnvironmental
Health and Injury Control, Centers for Disease Control, Atlanta, CA 30333, USA
Resulta of numerous studies have shown that smokers have a higher
incidence of sister chromatid exchange (SC6) in their lymphocytes and higher
levels of cotinine (a metabolite of nicotine) in their serum than nonsmokers .
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