| Objective Based on the great diagnostic and prognostic values of ct DNA,this study aims to reveal the mutation characteristics and genetic basis of Xinjiang Uighur NSCLC mutations,using the advanced,highly sensitive and specific ct DNA amplifications.The results have not only a theoretical significance but also clinical value for individualized approaches for Xinjiang Uygur patients.Methods Patients with advanced non-small cell lung cancer were admitted to the First Affiliated Hospital of Shihezi University School of Medicine and Kashi District Hospital during the2016-12-01 to 2017-11-31.In all,we enrolled 35 Uygur NSCLC patients,10 Uygur normal population,and 63 cases of Han nationality.Blood samples were collected,and plasma samples were kept.The genomic DNA and cf DNA were extracted.DNA electrophoresis was used to detect the DNA quality.Afterwards,cf DNAs were detected with qubit and2100 was used to determine the concentration and fragment size.The Illumina Hiseq 3000 system was used for sequencing,and 1021 genes were captured after sequencing.Raw reads were obtained,filtered,and referenced to the reference genomes for decontamination,and unique mapped reads aligned to the genome were obtained.Standard information analysis procedures were performed,including detection,annotation,and statistical analysis.The original data was aligned to the HG37 reference genome sequence for analysis of the point mutations(SNV),Indel,copy number variation(CNV),and structural variation(SV)using the Kayinga Autonomous Analysis Protocol.Results obtained were compared between two nations(Uygur vs Han,or patients vs health control).The frequency comparison was performed using the Fisher’s exact analysis,and the continuous quantitative data was compared by the t-test analysis.For all the presented data,P<0.05 was considered statistically significant.Results1.In 35 Uygur patients,males accounted for 62.9%(22)and women accounted for 37.1%(13).The average age was 56 years(23 to 84 years).There were 68.6%(24)adenocarcinoma cases and 20.0% squamous cell carcinoma(7)cases,another 2 cases of large cell neuroendocrine tumor,as well as 1 case of adenoid cystic carcinoma,1 case unknown.The stage-III patients accounted for 14.3%(5 cases),and stage-IV patients accounted for 85.7 %(30 cases).The patients with a history of smoking accounted for20.0 %(7 cases)and those non-smoking ones accounted for 80.0 %(28 cases).Among 63 Han patients,males accounted for 50.8 %(32)and females 49.2 %(31).The average age at diagnosis was 57(33 to 84 years).Adenocarcinoma patients accounted for 92.1 %(58),SCC patients accounted for 6.3%(4 cases)and 1 case was unknown.Stage-III patients accounted for 6.3%(4 cases),and stage-IV patients accounted for 93.7 %(59 cases).Patients with smoking history accounted for 3.2%(2 cases),non-smoking ones accounted for 96.8 %(61 cases).The proportion of adenocarcinoma in Uygur population was lower than that of Han population(68.6 vs.92.1)(Fisher’s exact test,p = 0.0041,OR 0.19);and the proportion of smokers was significantly higher in Uygur than the Han population(Fisher’s exact test,p = 0.0093,OR 7.46).2.After cfDNA extraction and detection of plasma,the mean cfDNA level per milliliter was determined.The cf DNA level in Uygur NSCLC was 29.9 ng/ml(6.7-129.8 ng/ml).The average plasma cf DNA content in Uyghur health control ones was 32.1 ng/ml(8.9-99.2ng/ml).The average cf DNA content in Han patients was 21.9 ng/ml(4.7-71.9 ng/ml).The plasma cf DNA concentration was significantly higher in the Uygur population than the Han population(T-test,p=0.0473).The above results suggest that the cf DNA level does not simply have the diagnostic and prognostic value for lung cancer.However,Uygur patients had a higher cf DNA content than Han patients.This difference might be caused by different ethnic genetic backgrounds,dietary conditions,and other factors.It also suggests that,for Uygur,liquid biopsy diagnosis may be more useful.3.Mutations were detected in 16 patients of the 35 Uyghur patients(45.7 %),and in 47 of63(72.6%)of 63 Han patients.The frequency of mutation was significantly higher in the Han nationality compared to Uygur(Fisher’s test,p = 0.0077).There were no significant differences in CNV and SV carriage between two groups.4.For those common mutant genes,only ABCC11 frequency was significantly higher than Uygur,and other genes were not statistically different.5.Further,in patients with high tumor mutation burden(TMB-H),this ratio in the two ethnic groups were 25.0 % and 14.9 %,respectively(the ratio of Uighur TMB-H patients was slightly higher,but without a significant difference,Fisher test,p = 0.4485).Among the Uygur TMB-H patients,3 were smokers and 1 was non-smokers;and 7 Han patients with TMB-H were all not smokers.The proportion of smokers in Uygur TMB-H patients was significantly higher than that of Han patients(Fisher’s exact test,p = 0.0242).6.Through the GO analysis,the differences in the function of the two ethnic mutant genes were revealed.There were five types of functional mutation genes found in the Uygur patient population but not found in the Han population.7.KEGG signaling pathway analysis showed a significant enrichment of Wnt pathway in Uygur patients but not in Han patients.Besides,m TOR,Notch,AMPK,VEGF and other pathways were found enriched in Han population but not the Uygur population.8.The clonal analysis showed no significant difference between two ethnic groups.ConclusionsUygur NSCLC patients have higher smoking rate,higher proportion of adenocarcinoma,and higher ratio of smokers in TMB-H patients compared to Han nationality.The plasma cf DNA content of Uygur patients was higher than the Han patients,but their overall mutation frequency was lower than Han population.The ABCC11 gene mutation frequency was higher in the Uygur patients than Han ones.Compared to the Han population,the Uygur population has a significant Wnt pathway enrichment,and five types of functional mutations represented(e.g.phosphoinositide phosphatase activity)were found only in the Uygur population. |
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