The polycyclic aromatic carcinogen-stimulated response of the tumor suppressorp53 in cultured cells
Abstract
The tumor suppressor protein p57 is involved in the recognition of DNA damage induced by radiation and chemicals. The effect of polycyclic hydrocarbons (PAH) on p53 was investigated by treating human mammary carcinoma MCF-7 cells with benzo (a) pyrene (B (a) P), with anti-B (a) P-7,8-diol-9,10-epoxide (B (a) PDE), an ultimate carcinogenic metabolite of benzo (a) pyrene, or with the potent carcinogen dibenzo (a,l) pyrene. Western blotting of lysates with antibody mAb1801 showed that B (a) PDE doses of 0.1 to 0.5 $\mu$M caused detectable increases in p53 protein. In cells treated with 0.3 $\mu$M B (a) PDE, p53 protein levels increased by 2 hours, reached a maximum between 8 and 24 hours and returned to control value by 120 hours after treatment. Levels of p21$\sp{WAF1}$ protein increased by 8 hours, reached a maximum by 48 hours and remained at that level through 168 hours after treatment. In cells treated with 1.2 $\mu$M B (a) P or with 0.005 $\mu$M DB (a,l) P, p53 protein levels increased by 12 hours after treatment, reached a maximum between 24 and 48 hours, and returned to control value by 120 hours after treatment. Levels of p21$\sp{WAF1}$ protein increased by 24 hours, reached a maximum by 48 hours and remained at that level through 168 hours after treatment. PAH-DNA adducts were quantitated by ($\gamma$-$\sp{33}$P) ATP postlabeling and HPLC separation. Adduct levels in B (a) PDE-treated cells dropped rapidly between 2 and 24 hrs after treatment, and subsequently decreased more slowly. Adduct levels in B (a) P- or in DB (a,l) P-treated cells reached their maximum 24-48 hours after treatment, dropped rapidly in the following 24 hours, and subsequently decreased more slowly. Increases in the proportion of cells in G2 were observed after treatment with either B (a) P or DB (a,l) P. These results indicate that PAH-induced DNA damage is recognized by a p53-dependent signal transduction pathway and induces a cell cycle arrest, and that a relationship exists between PAH-adduct levels and this response.
Degree
Ph.D.
Advisors
Baird, Purdue University.
Subject Area
Cellular biology|Molecular biology|Pharmacology
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