Open AccessPossible enhancing effects of atrazine on growth of 7,12‐dimethylbenz(a) anthracene‐induced mammary tumors in ovariectomized Sprague–Dawley rats
Author(s) -
Ueda Makoto,
Imai Toshio,
Takizawa Tamotsu,
Onodera Hiroshi,
Mitsumori Kunitoshi,
Matsui Takane,
Hirose Masao
Publication year - 2005
Publication title -
cancer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 1347-9032
DOI - 10.1111/j.1349-7006.2005.00008.x
Subject(s) - dmba , ovariectomized rat , 7,12 dimethylbenz[a]anthracene , medicine , endocrinology , estrogen , mammary tumor , tumor promotion , atrazine , carcinogenesis , mammary gland , hormone , cancer research , cancer , biology , breast cancer , pesticide , agronomy
Atrazine, one of the most commonly used herbicides in the world, has been reported to have endocrine disrupting effects in vivo . In the present experiment, influence of dietary atrazine on the late promotion/progression stage of mammary carcinogenesis in ovariectomized female Sprague–Dawley rats was examined after a single intragastric administration of 7,12‐dimethylbenz(a)anthracene (DMBA). When the incidence of palpable mammary tumors reached about 50%, the animals were subjected to ovariectomy and divided into tumor bearing [DMBA‐Tumor(+)] and non‐tumor bearing [DMBA‐Tumor(–)] groups, with subgroups of each fed a soybean‐free diet containing 0, 5, 50, or 500 p.p.m. atrazine for 34 weeks. At the completion of the study, the tumor volume in the 50 and 500 p.p.m. treatment Tumor(+) subgroups was greater than in the 0 p.p.m. control case. In the DMBA‐Tumor(–) group, higher incidences and volumes of the mammary tumors, with or without statistical significance ( P < 0.05), were observed in the 50 and 500 p.p.m. subgroups. Atrazine treatment tended to increase proportion of estrogen receptor α‐positive tumors and stimulated cell proliferation in the DMBA‐Tumor(+) group, but with no clear effects on serum hormone levels. The present study indicates that atrazine has a potential for enhancing the growth of mammary tumors, partly through increasing cell proliferation in the promotion/progression stage in female rats under ovarian hormone‐free conditions. ( Cancer Sci 2005; 96: 19 –25)