Assessment of the antioxidant/prooxidant status of murine skin following topical treatment with 12-O-tetradecanoylphorbol-13-acetate and throughout the ontogeny of skin cancer. Part II: Quantitation of glutathione and glutathione disulfide.
Tissue glutathione (GSH) and glutathione disulfide (GSSG) contents were quantitated in the skins of female SENCAR mice following the topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA), and in the skin tumors generated by an initiation-promotion protocol. Total epidermal GSHt (GSH + GSSG) and GSSG contents were not reproducibly and significantly altered 0.5, 4 or 24 h after one or four topical applications of 1 microgram TPA, relative to the values obtained in age-matched, solvent-treated mice. Similar findings held for dermal GSHt at all times of analyses, and for dermal GSSG contents 0.5 and 4 h after TPA application. However, dermal GSSG contents were slightly elevated 24 h after TPA application. The GSHt and GSSG contents of skins initiated with 10 nmol 7,12-dimethylbenz[a]anthracene (DMBA) and harvested 17, 29 and 37 days after the cessation of chronic treatment with acetone (14 weeks, twice a week) were comparable to the values measured in age-matched, non-treated skins. In contrast, GSHt contents of papillomas harvested 17, 29 and 37 days after the cessation of chronic treatment with 1 microgram TPA (14 weeks, twice a week) were 2- to 4-fold greater than the values measured in non-treated mice, and DMBA-initiated, acetone-promoted mice, and the non-tumorous tissue adjacent to the papillomas. Comparable changes did not occur in papilloma GSSG contents. GSHt contents in squamous cell carcinomas (SCC) were twice the values measured in papillomas and 5- to 8-fold greater than the values measured in non-treated skins, and the non-tumorous tissue adjacent to SCC. Similarly, GSSG contents in SCC were elevated multifold relative to papillomas, non-treated skin and the non-tumorous tissue adjacent to SCC. Epidermal cell suspensions prepared by the trypsin-flotation procedure retained less than 2% of their original GSHt content and had reduced GSHt/GSSG ratios. Collectively these studies suggest that (i) if promoting doses of TPA induce oxidative stress in murine epidermis, it cannot be detected by measurements of GSH/GSSG; (ii) the antioxidant capacity of epidermal cells prepared by the trypsin-flotation procedure is severely compromised; and (iii) GSHt contents progressively increase during skin tumor ontogeny.
Reiners
J J
JJ
Department of Carcinogenesis, University of Texas M.D. Anderson Cancer Center, Smithville 78957.
Kodari
E
E
Cappel
R E
RE
Gilbert
H F
HF
D015127:9,10-Dimethyl-1,2-benzanthracene; D000096:Acetone; D000287:Administration, Topical; D000375:Aging / Q000378:metabolism; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000378:metabolism*; D004817:Epidermis / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000031:analogs & derivatives* / Q000378:metabolism*; D019803:Glutathione Disulfide; D051379:Mice; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010212:Papilloma / Q000139:chemically induced / Q000378:metabolism*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate
D000096:Acetone; D015127:9,10-Dimethyl-1,2-benzanthracene; D005978:Glutathione; D013755:Tetradecanoylphorbol Acetate; D010100:Oxygen; D019803:Glutathione Disulfide