Protective Effect Of GGA On Ototoxicity Induced By Cisplatin; Effect Of Inflammatory Factors On Cisplatin Ototoxicity

Cisplatin can suppress the process of DNA replication in cancer cell.It shows a powerful antitumous effect in various cancer cells.World Health Organization(WTO) assessed the antitumor drugs which were up to one hundred in 1995.The result showed that cisplatin was second in the importance of curative effect,market and other aspects. Another statistics showed that 70-80 percent of chemotherapy programs contained cisplatin in our country.Cisplatin was used widely in the tumor therapy including ovarian cancer,prostatic carcinoma,carcinoma of testis,pulmonary carcinoma,nasopharyngeal carcinoma,esophageal carcinoma,Hokdkin's disease,breast cancer,cervical squamous cell carcinoma,thyroid carcinoma,osteogenic sarcoma and so on.It showed better curative effect.Simultaneously,the curative effect was together with the side effects which could not be neglected.The acoustic nerve,the kidney,the alimentary canal,the heart,the marrow and other organs were involved in the side effects which were induced by cisplatin.The clinical application of cisplatin was confined because of the side effects. So,looking for an effectively protective agent in order to relieve the side effects is very important for the clinical application and patients.Geranylgeranylacetone belongs to Terpene in pharmacology.It had a broad-spectrum antiulcer effect and was used on peptic ulcer patients at the very beginning.Then,it was reported to have a protective effect on several organs.It has been proved that it showed an protective effect on the atrophic gastritis,the ischemic-reperfusion heart damage,the endotoxin shock,the medicine inducing organ damage and so on.Heat Shock Protein(HSP) is a kind of protein family which is synthesized under stress.It acts like molecular chaperones and shows protective effects.According to the molecular mass,it can be divided into five species,including HSP100,HSP90,HSP70, HSP60 and small Heat Shock Proteins(sHSPs),HSP70 possesses the characteristics of widespread,high-conservatism and excitability and is capital in the HSP family.It acts like molecular chaperones which can protect other proteins against aggregation, solubilize initial,loose protein aggregates,assist in folding of nascent proteins or in refolding of damaged proteins,target severely damaged proteins to degradation,sequester damaged proteins to larger aggregates in case of excessive damage and inhibit apoptosis.C-Reactive Protein(CRP) is produced by liver during episodes of acute inflammation or infection and generally used as a measure of inflammatory disease.The density during episodes of acute inflammation steps up to thousandfold.In the body,CRP plays the important role of interacting with the complement system,an immunologic defense mechanism.It can identify extraneous material,activate complement system, strengthen cytophagocytesis,bind with Platelet Activation Factor(RAF) and chromosome, depress inflammatory reaction,eliminate the cell deoxyribonucleic acid in the necrotic tissue.Cysteine aspartic acic specific protease(Caspase),a family of cysteinyl aspartate-specific proteases,are central mediators of apoptotic and inflammatory pathways.Caspases are synthesized as inactive proenzymes,which are activated following cleavage at specific aspartate cleavage sites.It can cleavage the proteins with high selectivity at specific aspartate cleavage sites,which lead to activate or deactivate the proteins.Caspase-3 is the key executioners of apoptosis and an important part of cytotoxic T lymphocyte(CTL) mechanism.It is widely distributed,with high expression in cell lines of lymphocytic origin,suggesting that it may be an important mediator of apoptosis in the immune system.In this study,we aim to investigate whether Geranylgeranylacetone plays a protective effect on the ototoxicity induced by cisplatin and approach the conceivable mechanism.Otherwise,we discuss the effect of inflammatory factor on the cisplatin ototoxicity.We look forward to find an effective drug to relieve the side effects of cisplatin and find a mechanism of cisplatin ototoxicity. PartⅠProtective effect of GGA on ototoxicity induced by cisplatinObjective:Geranylgeranylacetone(GGA) has the ability to induce heat shock proteins(HSPs) and to protect cells from apoptotic insults.This study aims to investigate whether GGA has a protective effect on cisplatin(CDDP) ototoxicity.Methods:Twenty-four guinea pigs were divided into four groups randomly.The GGA+CDDP group were administrated GGA(600 mg/kg/day×7d) by intragastric administration,then,cisplatin was given(6mg/kg/day×3d) I.P.The GGA group were only administrated GGA(600 mg/kg/day×7d) by intragastric administration.The CDDP group were only given CDDP(6mg/kg/day×3d) I.P.The control group were given the same dose of 0.9%sodium chloride I.P.The weights were obtained before and after the experiment.The auditory thresholds were assessed using auditory brainstem response (ABR) test before and after the experiment.Hsp70 expression,C-reactive protein(CRP) expression and the activation of Caspase-3 were investigated by Western blot analysis. The amount of hair cells was counted under scanning electron microscopy(SEM).Results:The weight(170.50±7.82g) in the CDDP group was lower than that in the other three groups obviously.Though the weight(252.50±10.37g) in the GGA+CDDP group was lower than that in the GGA group and the control group,the descending tendency was more slow-moving than that in the CDDP group.The auditory threshold in the CDDP group(38.33±2.58dB) was higher than that in the other three groups.The auditory threshold in the GGA+CDDP group(18.33±2.58dB) was higher than that in the control group,but lower than that in the CDDP group.Western blot analysis showed that CRP expression in the GGA+CDDP group(0.31±0.02) was less compared with that in CDDP group(0.46±0.02).Hsp70 expression and the activation of Caspase-3 showed an adverse result.The HSP70 expression in the GGA+CDDP group(0.47±0.02) was more compared with that in the CDDP group(0.30±0.02).The activation of Caspase-3 was lower that that in the CDDP group.The ratio of missing outer hair cells(OHCs) in the CDDP group(0.42±0.02) were significantly higher than that in the GGA+CDDP group (0.24±0.02).Conclusion:Cisplatin showed an ototoxicity used by I.P.It was suggested that GGA had a protective effect on the cisplatin ototoxicity. PartⅡEffect of inflammatory factors on cisplatin ototoxicityObjective:This study aims to model the ototoxicity of cisplatin and investigate whether inflammatory factor has an effect on cisplatin(CDDP) ototoxicity.Methods:Twelve guinea pigs were divided into two groups randomly.The CDDP group were given CDDP(6mg/kg/day×3d) I.P.The control group were given the same dose of 0.9%sodium chloride I.P.The weights were obtained before and after the experiment.The auditory thresholds were assessed using auditory brainstem response (ABR) test before and after the experiment.Tumor necrosis factor-α(TNF-α) expression, IL-6 expression were investigated by Western blot analysis.The amount of hair cells was counted under scanning electron microscopy(SEM).Results:The weight(177.83±10.61g) in the CDDP group was lower than that in the control group(340±17.60g) obviously.The auditory threshold in the CDDP group (39.17±3.76dB) was higher than that in the control group.Western blot analysis showed that TNF-αexpression(0.58±0.02) and IL-6 expression(0.35±0.03) were higher in CDDP group.The ratio of missing outer hair cells(OHCs) in the CDDP group (0.43±0.03) was significantly higher than that in the control group.Conclusion:It was suggested that inflammatory factor had an effect on the cisplatin ototoxicity.