Response of human mammary epithelial cells to DNA damage induced by BPDE: involvement of novel regulatory pathways.
The responses of a line of normal human mammary epithelial cells, HME87, to treatment with the ultimate carcinogen benzo[a]pyrene diol epoxide (BPDE) were analyzed using a directed gene expression analysis technique, RAGE. Under conditions where cell number was decreased by 50% 24 or 48 h post-treatment, flow cytometry demonstrated no establishment of a G(1)/S arrest nor induction of apoptosis; cells continued to enter S phase from G(1) for at least 24 h but were blocked at G(2)/M. Using the RAGE technique, changes in gene expression were assayed for over 1000 genes, and multiple time-point data were collected for approximately 90 genes. In accord with the cell cycle studies, expression of the p21-WAF1 gene, the major mediator of p53-dependent G(1)/S arrest, did not increase until 24 h post-treatment. The expression of other target genes for transactivation by p53 was increased at early time points, including GADD45, an effector of the G(2)/M checkpoint, and WIP1. Analyses of proteins in treated cells indicated that p53 was phosphorylated at Ser15 but not at Ser20 within 30 min of treatment, and this correlated with an increase in the total amount of p53 protein. Significant expression changes were noted in a number of transcription factor genes, including ATF3 and E2A, genes that have not been previously connected to a response to DNA damage involving bulky chemical adducts. In addition, expression of the XPC gene was induced by BPDE treatment; the XPC product is thought to be involved in recognition of DNA damage by the nucleotide excision repair system.
Wang
Aijin
A
Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Science Park-Research Division, PO Box 389, Smithville, TX 78957, USA.
Gu
Jing
J
Judson-Kremer
Kimberly
K
Powell
K Leslie
KL
Mistry
Harsha
H
Simhambhatla
Padmaja
P
Aldaz
C Marcelo
CM
Gaddis
Sally
S
MacLeod
Michael C
MC
D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / Q000378:metabolism / Q000633:toxicity*; D001940:Breast / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002273:Carcinogens / Q000633:toxicity*; D002453:Cell Cycle / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004247:DNA / Q000187:drug effects*; D018736:DNA Adducts / Q000378:metabolism; D004249:DNA Damage; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
C493956:CDKN1A protein, human; D002273:Carcinogens; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D018736:DNA Adducts; D016159:Tumor Suppressor Protein p53; C043931:benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide-DNA; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D004247:DNA