title: Synergistic effect of malathion and estrogen on mammary gland carcinogenesis.
abstract: Breast cancer is the most frequent malignancy diagnosed in women and is             a classical model of hormone-dependent malignancy. Over the past 15-20 years,             epidemiological studies have pointed to an increased breast cancer risk associated             with prolonged exposure to female hormones. On the other hand, environmental chemicals             such as malathion, an organophosphorous pesticide used to control a wide range             of sucking and chewing pests of field crops, may be involved in the etiology of             breast cancers. Results indicated that estrogen alone increased average number             of lobules per mm2 of rat mammary glands in comparison to control and malathion             alone at 30, 124, 240 and 400 days after 5-day treatments. On the other hand,             malathion alone significantly increased the number of ducts in stage of proliferation             at 10-240 days after 5-day treatments. Furthermore, markers for cancer detection             such as mutant p53, c-myc, c-fos and CYPs proteins were overexpressed after treatments.             Atropine, an anticholinergic drug, counteracted these effects when it was combined             with malathion under similar conditions. The combination of malathion and estrogen             synergistically increased number of lobules and ducts per mm2 of rat mammary glands             after treatments and inducing mammary cancer. It can be concluded that combination             of an environmental substance such as the pesticide malathion and an endogenous             substance such as estrogen can enhance the deleterious effects in human mammary             glands inducing cancer and atropine is able to diminish these effects.
authors.affiliation: Institute for Advanced Research, Tarapacá University, Arica, Chile. gmc24@columbia.edu
authors.forename: Gloria M
authors.initials: GM
authors.lastname: Calaf
authors.forename: Carlos
authors.initials: C
authors.lastname: Echiburú-Chau
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D048708:Cell Growth Processes / Q000187:drug effects; D004357:Drug Synergism; D004967:Estrogens / Q000633:toxicity*; D005260:Female; D007306:Insecticides / Q000633:toxicity*; D008294:Malathion / Q000633:toxicity*; D008321:Mammary Glands, Animal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D010575:Pesticides / Q000633:toxicity; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004967:Estrogens; D007306:Insecticides; D010575:Pesticides; D001285:Atropine; D008294:Malathion