The Long-term Survival Analysis Based On The Comprehensive Treatment Of Intensity-modulated Radiotherapy For Locally Advanced Nasopharyngeal Carcinoma And The Study Of The Mechanism Of MiRNA-34a Regulating The Invasion And Metastasis Of Nasopharyngeal Car

PART 1: Long-term survival analysis of comprehensive treatment of locally advanced nasopharyngeal carcinoma patients based on intensity-modulated radiotherapy: a single-center studyBackground and objective: Nasopharyngeal carcinoma(NPC)is highly prevalent in southern China and Southeast Asia.70% of NPC patients were diagnosed with locally advanced disease at the first time of treatment.Intensity Modulated Radiation Therapy(IMRT)has become a mainstream technology for the treatment of NPC by effectively increasing the dose of target volume and protecting the surrounding organs at risk.This study retrospectively summarized the results of long-term follow-up of locally advanced NPC patients with IMRT,and analyzed survival outcomes,prognostic factors and failure modes.Methods: The study included 635 patients with locally advanced NPC who were admitted to the radiotherapy department of the Affiliated Tumor Hospital of Nanjing Medical University from January 2009 to December 2013.Clinical follow-up data were collected and analyzed retrospectively.Kaplan-Meier method was used for survival analysis.Log-rank test and Cox proportional hazards regression model were used to analyze the prognostic factors in patients with locally advanced NPC.Results: With a median follow-up of 63.5 months(range 5-92 months),the 5-year local recurrence-free survival(LRFS),regional recurrence-free survival(RRFS),distant metastasis-free survival(DMFS),disease-free survival(DFS)and overall survival(OS)rates were 88.4%,94.2%,79.2%,71.9% and 76.3%,respectively.Univariate analysis showed that the clinical stage was the prognostic factor of 5-year LRFS,RRFS,DMFS,DFS and OS.N-stage was the prognostic factor of 5-year RRFS,DMFS,DFS and OS.T staging was the prognostic factor of 5-year DMFS,DFS,and OS.Gender was the prognostic factor of 5-year DMFS.Whether the gross target volume dose(GTVt)> 70 Gy was the prognostic factor of 5-year DFS.Whether patient received chemotherapy was the prognostic factor of 5-year DMFS and OS.Whether patient received synchronous chemotherapy is the prognostic factor of 5-year DMFS.Multivariate analysis showed that T staging was an independent prognostic factor for 5-year LRFS.Clinical stage,N stage,and chemotherapy were independent prognostic factors for 5-year RRFS,DMFS,DFS,and OS.Of the 635 patients,175(27.6%)developed failure after treatment.The results of the failure modes analysis showed that distant metastases(131 cases,74.9%)were the main form of treatment failure,followed by local recurrence(n=67,38.3%)and finally lymph node recurrence(n=14,8%).Conclusion: IMRT improved long-term outcome in locally advanced NPC patients.T stage was an independent prognostic factor for 5-year LRFS in patients with locally advanced nasopharyngeal carcinoma.Clinical stage,N stage,and chemotherapy were independent prognostic factors for 5-year RRFS,DMFS,DFS and OS.Distant metastasis was the main reason for treatment failure.PART 2: Study on the mechanism of Mi R-34 a regulating invasion and metastasis of nasopharyngeal carcinomaObjective: Distant metastasis is the main reason for the current treatment failure of nasopharyngeal carcinoma.To explore the molecular mechanism of distant metastasis of nasopharyngeal carcinoma will provide a theoretical basis and therapeutic target for the resolution of distant metastasis of nasopharyngeal carcinoma.This study is designed to verify that Mi R-34 a reversed TGF-?-induced EMT,invasion and migration of NPC by targeting SMAD4.Methods: TGF-? continuously stimulates the NPC cells lines(CNE-1)to achieve a TGF-?-induced EMT model.CNE1 cell lines were transfectedwith mi R34 a mimic,inhibitor or mi R negative control (mi R-mimic/mi R-Inh/mi R-Ctrl).cell viability assay,wound healing assay and transwell invasionassay were performed to study the role of mi R-34a-in proliferation,migration andinvasion of NPC cells.Identification of target gene of mi R34a-5p was confirmed byluciferase reporter assays and then the association between the target gene SMAD4 and mi R34 a was examined by rescue experiment.Moreover,western blot analysis was applied to explore the underlying mechanisms.Results: Downregulated of SMAD4 suppressed TGF-? induced EMT,invasion and migration.Mi R-34 a directly targets SMAD4 in NPC cells.Mi R-34 a moderates the EMT,invasion and migration induced by TGF-? in NPC cell lines.Restoring expression of SMAD4 rescues mi R-34 a suppressed EMT,invasion and migration.Conclusion: Mi R-34 a reversed TGF-?-induced epithelial-mesenchymal transition via suppression of SMAD4 in NPC cells and provided a new therapy target for NPC.