Rebecca J. Van Beneden
Department of Zoology, University of Maine, Orono, Maine
Cancers of the reproductive system are among the leading causes of mortality in women in the United States. While both genetic and environmental factors have been implicated in their etiology, the extent of the contribution of environmental factors to human diseases remains controversial. To better address the role of environmental exposures in cancer etiology, there has been an increasing focus on the development of nontraditional, environmentally relevant models. Our research involves the development of one such model. Gonadal tumors have been described in the softshell clam ( Mya arenaria) in Maine and the hardshell clam (Mercenaria spp.) from Florida. Prevalence of these tumors is as high as 40% in some populations in eastern Maine and 60% in some areas along the Indian River in Florida. The average tumor prevalence in Maine and Florida is approximately 20 and 11%, respectively. An association has been suggested between the use of herbicides and the incidence of gonadal tumors in the softshell clam in Maine. The role of environmental exposures in the development of the tumors in Mercenaria in Florida is unknown; however, there is evidence that genetic factors may contribute to its etiology. Epidemiologic studies of human populations in these same areas show a higher than average mortality rate due to cancers of the reproductive system in women, including both ovarian and breast cancer. The relationship, if any, among these observations is unknown. Our studies on the molecular basis of this disease in clams may provide additional information on environmental exposures and their possible link to cancer in clams and other organisms, including humans. -- Environ Health Perspect 105(Suppl 3):669-674 (1997)
Key words: comparative carcinogenesis, gonadal tumor, Ah receptor, dioxin, bivalves, TCDD, nontraditional models
This paper was presented in part at the Workshop on Hormones, Hormone Metabolism, Environment, and Breast Cancer held 28-29 September 1995 in New Orleans, Louisiana. Manuscript received at EHP 6 June 1996; manuscript accepted 29 August 1996.
The photoaffinity binding studies were done by D.J. Brown as part of his doctoral thesis from the Department of Cell Biology, Duke University Medical Center, Durham, NC. These studies were made possible by the materials and guidance supplied by G. Clark at the National Institute of Environmental Health Sciences (currently at Xenobiotic Detection Systems, Inc.). I thank G. Gardner for his collaboration and input into this investigation. This work was supported in part by grant R01 RR08774-01 from the National Institutes of Health.
Address correspondence to Dr. R.J. Van Beneden, Department of Zoology, 5751 Murray Hall, University of Maine, Orono, ME 04469-5751. Telephone: (207) 581-2602. Fax: (207) 581-2537. E-mail:rebeccav@maine.maine.edu
Abbreviations used: AhR, aryl hydrocarbon receptor; BRCA, breast cancer associated; EGF, epidermal growth factor; HAH, halogenated aromatic hydrocarbon; kDa, kilodaltons; 2,4-D, 2,4-dichlorophenoxyacetic acid; 2,4,5-T, 2,4,5-trichlorophenoxyacetic acid; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDF, tetrachlorodibenzofuran.
Last Update: April 10, 1997