Cigarette smoking has been identified as a major etiologic factor for urinary bladder cancer in the United States and is estimated to account for approximately 50% of all cases. Although several carcinogens, co-carcinogens, and promoters have been identified in cigarette smoke, which of these are relevant to the development of human bladder cancer is unknown. Acrolein is present in relatively large quantities in cigarette smoke (10-140 Mug/cigarette) and is also an economically important intermediate in the chemical industry, where process workers often have an increased incidence of bladder cancer. Cyclophosphamide, a chemotherapeutic alkylating agent used in the treatment of neoplastic and autoimmune diseases, has as a side-effect the induction of hemorrhagic cystitis and eventually carcinoma of the bladder. Data from human and animal studies have identified acrolein (a metabolite of cyclophosphamide) as the agent responsible for the hemorrhagic and the carcinogenic effects of cyclophosphamide on the bladder. We propose to investigate the interactions of acrolein on the bladder epithelium in vitro and in vivo. Short-term assays will be performed utilizing scanning electron microscopy and autoradiography to determine a dose response for the effects on acrolein on urothelial cytotoxicity and consequent regenerative proliferation. Based on the short-term studies, long-term bioassays will be performed evaluating the possible carcinogenic, initiating, and promoting activity of acrolein for the bladder. To develop an understanding of the molecular events which underlie such changes in morphology, extensive biochemical investigations are also proposed. Acrolein will be reacted with deoxynucleotides in vitro and the products identified. These will be used for the qualitative and quantitative determination of adducts after reaction of acrolein with DNA in vitro and after exposure of cultured cells to acrolein. Ultimately, these studies will be extended to the detection and quantitation of adducts formed in the bladder epithelium of the rat following acrolein administration. The miscoding potential of acrolein adducts in DNA will also be evaluated. In addition, the amounts of acrolein in biological fluids, particularly urine, will be determined by methods that will be developed. Ultimately, these analytical procedures should be useful for examination on humans exposed to acrolein.
