Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1
carcinogens:
infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified
steroid hormone like (e.g.,
oxysterol-like,
catechol estrogen quinone-like, etc.) metabolites and related
DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with
urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of
sterol derivatives are metabolized to active
quinones that can modify
DNA, which in other contexts can lead to breast and other
cancers, helminth parasite associated
sterols might induce
tumor-like phenotypes in the target cells susceptible to helminth parasite associated
cancers, i.e., urothelial cells of the bladder in the case of
urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced
cancers originate from parasite
estrogen-host epithelial/urothelial cell chromosomal
DNA adducts, and here we review recent findings that support this conjecture.