Arsenic is a known human
carcinogen, inducing
tumors of the lung, urinary bladder, skin, liver and prostate. However, there are no reports of prostate
tumors induced by
arsenicals in in vivo animal models. In a previous study, we found that
HMGB2 expression was a predictive marker for prostate
carcinogens in the rat 4-week repeated dose test. In this study, six-week-old male F344 rats were orally treated with a total of six chemicals (
2-acetylaminofluorene (2-AAF),
p-cresidine,
dimethylarsinic acid (DMA),
glycidol,
N-nitrosodiethylamine and acrylamide) for four weeks. Animals were sacrificed at the end of the study, and
HMGB2 and Ki-67 immunohistochemistry was performed. The numbers of HMGB2- and Ki-67- positive cells in all prostate lobes were significantly increased by DMA, one of the
arsenicals, compared with the controls. Meanwhile, the number of Ki-67-positive cells in lateral and dorsal prostate lobes was significantly decreased by
2-AAF with the reduction of
body weight, but
HMGB2 expression was not. The other chemicals did not change
HMGB2 and Ki-67 expression. These data indicate that DMA may have an ability to enhance prostate
carcinogenesis.