Aloe-emodin Enhances Radiosensitivity In Human Nasopharyngeal Carcinoma Cells And Cervical Cancer Cells

Radiation therapy is the main treatment modality of nasopharyngealcarcinoma with a higher incidence in head and neck, because thecomplexity and importance of the surrounding tissue. Cervical cancer hasa high incidence, and the most need radiation therapy either primary orpostoperative cervical cancer patients. The tumor dose is increased inorder to improve the treatment efficiency. The threshold dose needs toreduce and limit, in order to reduce the surrounding normal tissueradiation injury. Trying to increase the tumor radiation dose, to minimizethe normal tissue around the tumor radiation dose within certain limits,and this contradiction exists throughout the Radiation Therapy. one of themethods to resolve or reduce the contradictions is to use a radiationsensitizer，Increasing the radiosensitivity of tumor cells.Aloe-emodin is a extract of traditional Chinese herbal medicine aloevera, widely grown around the world for a long history. For its cultivationtechnology simple, widespread prescription, the cultivation and use ofaloe vera plant is particularly common in our county. The common role ofaloe-emodin has diarrhea, anti-virus, protecting the liver and normal skin,cosmetic effect. Aloe vera have been reported that the inhibition ofglioma, nasopharyngeal cancer, lung cancer, liver cancer, prostate cancer,skin cancer and neuroectodermal tumor cancer cell grown at home andabroad in recent years. One of the anti-tumor mechanisms is that aloe–emodin block tumor cell cycle in radiosensitive G2/M phase.Based on the above theory, the present study intends to aloe-emodinenhanced radiosensitivity of nasopharyngeal carcinoma cells and cervical cancer cells, exploring its potential mechanisms.Objective:The aim of this study was to investigate the effects of aloe-emodin onthe radiosensitivity of human nasopharyngeal carcinoma cells andcervical cancer cells.Methods:1. Nasopharyngeal carcinoma cells and cervical cancer cells weretreated with various concentration of aloe-emodin, and cells proliferationwas measured by MTT assay.2. Colony-forming assay for tumor cell radiosensitivity. Analysis ofnasopharyngeal carcinoma cells and cervical cancer cells D0, Dq, N, SERand SF2radiosensitivity parameter value change.3. The distribution of nasopharyngeal carcinoma and cervical cancercells cycle were analyzed by flow cytometry with Aloe-emodin, radiationand aloe-emodin combination with radiation at treated at differents timepoints.4. The expression of nasopharyngeal cell cycle protein CycinB andcervical cancer cells protein r-H2AX were investigated by western blotassay，and cell were treated with Aloe-emodin, radiation and aloe-emodincombination with radiation.5. The alkaline phosphatase activity of nasopharyngeal carcinoma andcervical cancer cells were analyzed， and cells were treated byAloe-emodin, radiation and aloe-emodin combination with radiationtreated tumor cells at differents time points.ResultsGrowth inhibitory effects ofAE on CNE and Hela cells AE inhibited the proliferation of CNE and Hela cells in aconcentration-and time-dependent manner.Effect ofAE on radiosensitization of CNE and Hela cellsThe radiobiological parameters D0, Dq, N and SF2decreased andthe SERD0and SERDq of CNE and Hela increased in response to AE ina concentration dependent manner in vitro, and the effect was enhancedby combination treatment compared to the effect of radiation alone.Effects of AE and radiation on CNE and Hela cells cycle distributionassessed by flow cytometry.CNE cells treated with radiation or AE alone for12h showed anincrease in the G2/M phase and a decrease in the G0/G1phase, The Sphase increased significant in the AE treated group. Cells treated with thecombination of radiation and AE for12h showed a decrease in the G2/Mand S-phase peaks, and an increase in the G0/G1peak compared to thosetreated with AE or radiation alone. At24,48, and72h, the combinationof AE with radiation decreased the G2/M peak, while the sub-G1peak(apoptosis peak) emerged in a time-dependent manner.Hela cells treated with radiation or AE alone for12h showed anincrease in the G2/M phase, particularly obviously with the combinationradiation with AE. A significant increase in the number of cells in the Sphase was observed, and the sub-G1peak (apoptosis peak) emerged in atime-dependent manner.Cyclin B andγ-H2AX expression by western blottingCNE treated with radiation or AE for12h showed a higher level ofexpression of cyclin B than cells treated with the combination of radiationand AE as determined by western blotting. Furthermore, combination treatment downregulated cyclin B expression in a time-dependent manner,with the highest effect observed in the combination group at72h.Hela treated with radiation or AE alone showed a lower level ofexpression of γ-H2AX than cells treated with the combination ofradiation andAE.The relative activity ofALPThe ALP activity of CNE and Hela was increased by radiation, AEand the combination of radiation with AE in a time dependent manner,and the effect was enhanced by combination treatment compared to theeffect of radiation orAE alone.Conclusion:1. Aloe-emodin inhibited the proliferation activity of nasopharyngealcarcinomacells and cervical cancer cell.2. Aloe-emodin enhanced radiosensitivity of nasopharyngealcarcinoma cells andcervical cancer cells.Mechanisms:(1)Aloe-emodin inhibited nasopharyngeal carcinoma cellsand cervical cancer cell proliferation;(2)Aloe-emodin arrestnasopharyngeal carcinoma cells and cervical cancer cells in G2/M phaseand inducing apoptosis;(3)Induced nasopharyngeal carcinoma cells andcervical cancer cell differentiation.