Establishment Of Cisplatin Resistant Models,Screening Of Drug Resistance Genes And IAP-1 Induced Cisplatin Resistance Related Analysis

INTRODUCTIONNasopharyngeal cancer(NPC)is a common malignant tumor of the head and neck originated in nasopharynx,especially in Guangdong Chinese,etc.Most patients first present with cervical lymph node metastasis because NPC is rich in lymphatic reflux and the location is concealed which is difficult to identify by physical examination.In recent decades,although the diagnose and treatment of NPC has developed significantly,the 5-year survival rate of stage IV NPC is only approximately 65%.There is an approximately 10%-20%recurrence rate in NPC patients caused by distant metastasis or drug resistance due to individual heterogeneity.Therefore,the overall survival rate is still comparatively low in patients in advanced phases,even after concurrent chemo-radiotherapy.The primary and development resistance of chemotherapy drugs will limit the choice of selectable drugs.However,the specific processes involved in recurrent/metastasis nasopharyngeal carcinoma still lacks of reports.Therefore,clarifying the resistance mechanism in NPC will help diagnosis in an early stage and help determine the appropriate therapy,which will improve the survival rate and life quality of NPC patients.MATERIALS AND METHODSWe first successfully established two cisplatin-resistant NPC cell lines(HNE-1/DDP and CNE-2/DDP)by gradually increasing doses of cisplatin,and the xenograft nude mouse models,and examined the biological function differences,such as proliferation,migration,apoptosis,clone formation etc.Then we performed mRNA sequencing of the parent and drug-resistance cell lines and analyzed the differentially expressed genes(DEGs)from high-throughput sequencing results using bioinformation and notice several pathways and genes those are highly relative to the platinum resistance.Next,we silenced the notable DEGs in the drug-resistant NPC cell lines and overexpressed them in parental cell lines in vitro and in vivo to demonstrate the functional changes and investigate the potential mechanism behind the cisplatin-resistance progress in NPC.RESULTSThe resistance cell lines we established presented a strong resistance to the cisplatin with separate RI of 12.02 and 16.02.The apoptosis of drug-resistence cells compare with the parent cell lines reduced,however,there is no significant differences in cell migration,clone formation and proliferation.Among the 15,403 DEGs in HNE-1 experiment groups,948 showed a significant difference,and 458 were filtered as overexpressed.9 DEGs were found in the classic platinum drug-resistance pathway.Interestingly,3 DEGs(ATM,IAP-1,IAP-2)also presented in the top 5 differentially expressed pathways,while elevated IAP-1 had the highest log2 ratio(log2 ratio,4.22;probability,0.95).High IAP-1 in resistance cell lines contributed to a higher cisplatin IC50 and reduced cell apoptosis,while cell growth,cloning and migration were poorer.In vivo,high IAP-1 expression slowed tumor growth but reduced cisplatin sensitivity which cut the drug efficiency.DISCUSSIONIn vitro and:in vivo experiments demonstrated that elevated IAP-1 plays a vital role in cisplatin resistance in NPC and its biological function agrees with its clinical relevance.At the same time,results from open resource databases show that elevated IAP-1 is related to a worse 5-year survival rate and a higher possibility of recurrent and tumor grade.In summary,overexpressed IAP-1 leads to poor survival and worse response to cisplatin chemotherapy and it may work as a novel prognostic indicator in NPC and a potential therapeutic target for improving the cisplatin sensitivity.