Interleukin-1alpha up-regulation in vivo by a potent carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) and control of DMBA-induced inflammatory responses.
Tumor-initiating properties of complete carcinogens such as 7,12-dimethylbenz(a)anthracene (DMBA) are well known but not the mechanism of DMBA-mediated tumor promotion. Our hypothesis is that interleukin (IL)-1alpha, an early proinflammatory cytokine that initiates a cascade of other cytokines and growth factors, is up-regulated by DMBA and contributes to inflammation and carcinogenesis. We found that topical exposure of SENCAR mice to a carcinogenic DMBA dose indeed triggers significant increases in mouse skin IL-1alpha and IL-1alpha mRNA. Five DMBA applications (200 nmol each) caused a statistically significant (P = 0.02) increase in serum IL-1alpha, comparable with that induced by 12-O-tetradecanoylphorbol-13-acetate, a potent tumor promoter. IL-1alpha increase in serum was evident 24 h after the first DMBA application, whereas that in skin required five DMBA doses and became statistically significant (P < 0.0003) 48 h later. Skin IL-1alpha enhancement was preceded by a 6-fold up-regulation of IL-1alpha mRNA. A pretreatment with antimurine IL-1alpha antibody (Ab) nearly abolished DMBA-induced IL-1alpha mRNA (P = 0.0001) in skin and substantially decreased IL-1alpha in serum. Infiltration of polymorphonuclear leukocytes into skin was elevated 6-fold (P = 0.002) and >10-fold (P = 0.001) 24 h and 48 h after the fifth DMBA exposure, respectively. A pretreatment with anti-IL-1alpha Ab decreased polymorphonuclear leukocyte infiltration by >65% (P < 0.02), which suggests that this process is at least 65% under IL-1alpha control. Anti-IL-1alpha antibodies had no effect on edema, thus dissociating the two inflammation markers. Injecting anti-IL-1alpha Ab before DMBA applications significantly (P < 0.04) decreased the volume of carcinomas (CAs) in comparison with CAs that arose in mouse skin injected with a nonspecific serum. These results prove that IL-1alpha is induced by a carcinogenic DMBA dose and contributes to DMBA-induced inflammation and volume of CAs, hallmarks of tumor promotion and progression.
Li
Xiaolu
X
Department of Environmental Medicine, New York University School of Medicine, New York, New York 10016, USA.
Eckard
Jonathan
J
Shah
Rajendra
R
Malluck
Chenlu
C
Frenkel
Krystyna
K
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002273:Carcinogens / Q000633:toxicity*; D004249:DNA Damage; D004487:Edema / Q000139:chemically induced / Q000378:metabolism; D005260:Female; D007074:Immunoglobulin G / Q000494:pharmacology; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics / Q000276:immunology; D051379:Mice; D018632:Mice, Inbred SENCAR; D009504:Neutrophils / Q000276:immunology / Q000473:pathology; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D012878:Skin Neoplasms / Q000139:chemically induced / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity; D015854:Up-Regulation
D000906:Antibodies; D002273:Carcinogens; D007074:Immunoglobulin G; D007375:Interleukin-1; D012333:RNA, Messenger; D015127:9,10-Dimethyl-1,2-benzanthracene; D013755:Tetradecanoylphorbol Acetate