Experimental Study About Inhibitory Effect Of Iodine-125 On The Growth Of Nasopharyngeal Carcinoma CNE-2 Xenografts In Nude Mice

ObjectiveTo observe the inhibitory effects of 125I interstitial brachytherapy on the growth of nasopharyngeal carcinoma CNE-2 xenografts in nude mice and observe the influence of expressions of survivin、MVD、VEGF and HIF-1 a for interstitial brachytherapy with 125I seeds on the cancer cell in nude mice with the human nasopharyngeal carcinoma.Materials50 nude mice models were established first through the injection of the cells into nude mice subcutaneously.when the transplanting tumor maximum diameter of (10 ±0.5) mm.40 mice were selected as experimental which tumor morphology comparison rules and nearly spherical. Mice were divided into treated group and control group randomly,The treated group was randomly divided into 3 groups,each group of 10.According to the particles into the activity is divided into high dose group(0.9 mCi).middle dose group(0.6mCi),low dose group(0.3mCi),control group with blank particies(OmCi).After seeds implantation,measured the length of the tumor size,calculated tumor volume.Determined by immunohistochemical techniques to express survivin, MVD, VEGF, HIF-1 a protein.Electron microscopy was used to detect the apoptosis.Results1. Continuous low-dose irradiation of 125I seeds has an inhibitory effect on growth of transplanted tumors in nude mice. HE staining shows that 125I seeds have a lethal effect on transplanted tumors of nude mice; moreover, the killing effect is enhanced with increasing radiation dose.2.125I seeds have no obvious damage to the liver and kidney functions in nude mice, yet high-dose group is more susceptible to skin radiation damage than other groups.3. Immunohistochemistry confirms that the expressions of survivin, MVD, VEGF and HIF-la proteins decrease in the experimental groups. 4. TEM reveals well growing tumor cells in control group, with little apoptosis. In the experimental groups, apoptotic cells in various phases are visible.Conclusions1.The expressions of VEGF,survivin,HIF-1α,MVD in tumor are suppressed,and the 125I seeds implantation has the anti-tumor capillaries production function and promote apoptosis which can inhibit the growth of tumor cell.2.Appropriate dose of 125I continued exposure could significantly inhibit the growth of nasopharyngeal carcinoma CNE-2 xenografts in sustained, not only cannot increase the efficacy of the high dose, but increased side effects.