Alteration of radiation-sensitive processes associated with cancer and longevity by dietary 2-mercaptoethanol.
BACKGROUND
Previous results demonstrated dietary 2-mercaptoethanol (2-ME) delayed appearance of cancer in certain murine strains. In addition, it had a benefit not found with other organosulfurs, in that it completely prevented spontaneous development of cancer in BXSB-Yaa + over an entire lifespan.


OBJECTIVE
These benefits raise the question: What, if any, alteration of radiation-induced tumorigenesis would 2-ME impart that may differ from that of other sulfur antioxidants? This is relevant based on the extensive use of radiation in diagnoses and therapy and 2-ME's superior in vitro and in situ immune enhancement properties.


METHODS
This was addressed by exposing long-lived, B10.A (4R) mice to sublethal, 5.5 Gy ionizing gamma-rays and then tumor development monitored over a lifetime.


METHODS
Two-tailed P-values were determined using the Fischer's Exact Test.


RESULTS
The only tumors detected were mammary and only in animals that were both exposed to radiation and not treated with 2-ME. The 43% incidence differed significantly from the absence of tumors in non-irradiated mice that were or were not exposed to 2-ME and in those irradiated and treated daily with 2-ME, irrespective of whether treatment was started prior to or post irradiation. However, quite unexpectedly, radiation shortened longevity 29% from undefined causes, including cancer, in animals pretreated with 2-ME; longevity was not altered in those not pretreated or if treatment was started post-irradiation.


CONCLUSIONS
The findings have relevance for cancer prevention and the controversy relative to ''long term survival/safety'' of currently used antioxidants as free radical scavengers in humans undergoing radiotherapy.
Department of Microbiology, University Minnesota Minneapolis, MN, USA.
Robert E
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D000818:Animals; D004032:Diet; D004195:Disease Models, Animal; D005720:Gamma Rays / Q000009:adverse effects; D006801:Humans; D008136:Longevity; D008297:Male; D008623:Mercaptoethanol / Q000008:administration & dosage*; D051379:Mice; D009369:Neoplasms / Q000209:etiology* / Q000401:mortality*; D011832:Radiation Injuries / Q000150:complications; D011836:Radiation Tolerance / Q000187:drug effects*
D008623:Mercaptoethanol