Subject(s)
Cell Transformation, Neoplastic , Embryo, Mammalian/radiation effects , Misoprostol/pharmacology , Radiation-Protective Agents/pharmacology , Animals , Cell Survival/drug effects , Cell Survival/radiation effects , Cells, Cultured , Cricetinae , Embryo, Mammalian/cytology , Embryo, Mammalian/drug effects , Female , Mesocricetus , Organ Culture Techniques , Pregnancy , X-RaysABSTRACT
Misoprostol, a PGE1 analog, is an effective radioprotector of murine intestine and hematopoietic and hair cell renewal systems. The radioprotective nature of misoprostol was extended to examine its ability to influence clonogenic cell survival and induction of oncogenic transformation in Syrian hamster embryo cells exposed to X rays in utero and assayed in vitro. Hamsters in their 12th day of pregnancy were injected subcutaneously with misoprostol, and 2 h later the pregnant hamsters were exposed to graded doses of X rays. Immediately after irradiation, hamsters were euthanized and embryonic tissue was explanted into culture dishes containing complete growth medium. After a 2-week incubation period, clonogenic cell survival and morphologically transformed foci were determined. Survival of misoprostol-treated SHE cells was increased and yielded a dose reduction factor of 1.5 compared to SHE cells treated with X rays alone. In contrast, radiation-induced oncogenic transformation of misoprostol-treated cells was reduced by a factor of 20 compared to cells treated with X rays alone. These studies suggest that misoprostol not only protects normal tissues in vivo from acute radiation injury, but also protects cells, to a large extent, from injury leading to transforming events.
Subject(s)
Cell Death/radiation effects , Cell Transformation, Neoplastic/drug effects , Embryo, Mammalian/radiation effects , Misoprostol/pharmacology , Radiation-Protective Agents/pharmacology , Animals , Cell Death/drug effects , Cell Survival/drug effects , Cell Survival/radiation effects , Cell Transformation, Neoplastic/radiation effects , Cells, Cultured , Clone Cells , Cricetinae , Dose-Response Relationship, Radiation , Embryo, Mammalian/drug effects , Female , Mesocricetus , Pregnancy , X-RaysABSTRACT
PURPOSE: Prostaglandins are associated with a variety of both pathologic and normal physiological effects in mammals. Among this broad array of effects, prostaglandins have been shown to provide protection to tissues from a variety of injurious agents including ionizing radiation. Of the prostaglandins tested to date, an analogue of prostaglandin E1, misoprostol (cytotec) was found to be a very effective radioprotector. The purpose of this study was to assess the ability of misoprostol to protect cells from the cytotoxic and oncogenic effects of ionizing radiation. METHODS AND MATERIALS: Pregnant Syrian hamsters were injected subcutaneously with 125 micrograms misoprostol/100 g body weight 2 h before being exposed to graded doses of X rays. Embryos were excised immediately after irradiation and cells were explanted into culture dishes. Following 14 days of incubation, cells were fixed in formalin and stained with giemsa for examination of cell clonogenicity and morphological transformation. RESULTS: First, misoprostol protected cells from some degree of radiation toxicity. A reduction in cell killing by a factor of 1.5 was seen at 10% cell survival. Second, based on transformation studies, a higher frequency of oncogenic transformation is seen for cells exposed in utero to graded doses of X rays alone than for cells exposed to the combination of misoprostol followed by radiation. In the presence of misoprostol, transformation is reduced by a factor of 20 at the level of 10(-3) transformants per surviving cell. CONCLUSION: Misoprostol may have clinical utility, not only in protecting selected normal tissues during cancer therapy, but it may also be useful in protecting cells from secondary tumors caused by ionizing radiation.
