Clinical Characteristics Analysis Of Patients With Osteosarcoma Analysis Between AEG-1 Gene Polymorphisms And Osteosarcoma Susceptibility

BackgroundOsteosarcoma(OS)is the most common primary bone malignancy,which occurs frequently in adolescents,and it has high extremely malignant grade,with metastasis in the early stage,and had poor prognosis.Incidence rate of osteosarcoma is altered with the age varying,with a bimodal distribution.The first peak of osteosarcoma occurrence is in the adolescents age ranged 10-20 years,and the other peak occurs in the elderly population aged over 65 years.It is generally believed that men have a higher incidence of osteosarcoma than women.Osteosarcoma usually occurs in the capitulum of bone,especially terminal femur,proximal tibia,followed by the proximal humerus.Osteosarcoma is rare discovered in other parts.Most of osteosarcoma is osteolytic OS,but a few of them are osteogenic type.Osteosarcoma contains different components,such as cartilage,fibrous tissues and osteogenic tissues.A common feature of this tumor is the formation of immature osteoid tissue,or called as osteoid(tumorous bone).Malignancy and the tendency of metastasis or diffuse of osteosarcoma largely depends on the histopathological grades of it.When observed the tumor cells under microscope,cells and nuclei are of different sizes and shapes,including small multicellular giant cells,spindle cells,immature chondrocytes and malignant osteoblasts,with large and dark nuclei.Some osteosarcomas can be cured by simple surgery,but most of them have the symptoms of rapid local invasion and early lung metastasis.Recent years,the treatment of osteosarcoma hastremendous improvement,but more than half of osteosarcoma patients still die from metastasis and recurrence.Although the pathogenesis of osteosarcoma is still unknown,more and more studies have confirmed that gene mutation plays an important role in the etiology of osteosarcoma.Study of the molecular mechanism of osteosarcoma occurrence and development is helpful to improve the understanding of tumor mechanism and promote the early screening and treatment in-depth.Genetic polymorphisms refers to the existence of two or more discontinuous variants or genotypes or alleles in a biological population at the same time and often,which can lead to the diversity selection of transcription and translation in the process of biological reproduction,also known as hereditary polymorphism or polymorphism.Genetic polymorphism can not only maintain a certain accuracy of the genetic code,but also a certain tolerance,which is of great significance to maintain the homeostasis and diversity of the biosphere.Among them,single nucleotide polymorphism(SNP)is the most common form of genetic variation in humans,accounting for more than 90%of known polymorphisms.In essence,polymorphisms are produced by variation at the gene level,generally occurring in regions that do not encode proteins or in the genetic sequences that do not perform major regulatory functions.SNPs located in the promoter region can change the transcription and expression of the gene,leading to the up-regulation or inhibition of the gene expression,which is also the genetic basis of the complex and diverse phenotype in the evolution process of biological population.5’-untranslated regions(5’-UTR)overlaps the promoter region in the base position,so it is also involved in the regulation of gene transcription expression.SNPs in 3’-untranslated regions(3’-UTR)and intron regions can lead to shear and splicing errors of mRNA,resulting in abnormal mRNA which affecting gene expression.SNP has many advantages,such as wide quantity distribution,strong genetic stability,large phenotypic difference and easy and rapid large-scale screening.SNP helps to explain individual phenotypic differences,susceptibility to diseases,tolerance to various drugs,and response to environmental factors.SNP has been widely used in research on complex diseases,such as genetic susceptibility to malignant tumors,and drug resistance.SNP can not only play a role by changing the gene sequence of the protein coding region,but also affect the expression or functional activity of the protein by changing the gene expression in the regulation region.The occurrence,development and metastasis of malignant tumors are impacted by multiple factors.Many studies have shown that genetic polymorphism is closely related to the susceptibility and prognosis of patients with osteosarcoma.It has been confirmed by previous studies,that astrocyte elevated gene-1(AEG-1)gene,also known as metadherin(MTDH),is a newly discovered important oncogene,which is overexpressed in a variety of tumors.AEG-1 plays an important role in the occurrence and development of tumors,and it is involved in the invasion,metastasis,angiogenesis,drug resistance and prognosis of many tumors.AEG-1 gene can up-regulate the expression level of matrix metalloproteinase 2(MMP-2)through endothelin-1(ET-1)/endothelin A receptor(ETAR)signaling pathway,thus promoting cell invasion and resistance to chemotherapy drugs of osteosarcoma.In osteosarcoma,the knockdown of AEG-1 could significantly inhibit cell migration and invasion,as well as EMT.Rs16896059(-797G/A)polymorphism was located at the promoter region of AEG-1 gene,meanwhile rs1311(c.*1463T>C)was located at the 3’-untranslated region behind Exon 12.The two variants might be involved in the transcription,shear and splicing of AEG-1 gene,thus regulating the expression of AEG-1 gene.Based on this,we hypothesized that these two polymorphisms might take part in development and progression of osteosarcoma.However,there were few researches constructed to address the relationship between rs 16896059 and rs1311 polymorphisms and the susceptibility to osteosarcoma.The clinical significance of AEG-1 genetic polymorphisms in development and progression of osteosarcoma still remained poorly known.PART 1Clinical characteristics analysis of patients with osteosarcomaObjective:Present retrospective analysis was aimed to explore the demographic characteristics and clinical characteristics of osteosarcoma(OS)patients in Affliated Hospital,Baotou Medical College during 2013 January and 2015 December.Methods:Via consulting medical records,questionnaires and telephone follow-up methods,we analyzed the demographic characteristics and clinical characteristics of osteosarcoma patients in Affliated Hospital,Baotou Medical College during 2013 January and 2015 December.The characteristics included age,gender,nation,drug history,medical history,smoking,drinking,trauma history,tumor location,metastasis,pathological classification and other information.Results:There were 35 osteosarcoma patients were recruited from the Affliated Hospital,Baotou Medical College during 2013 January and 2015 December.Basic characteristics of osteosarcoma patients were as the follows:mean age of the patients was 24.1±10.5,age ranged between 10 and 20 years old were 27 cases(77.14%);there were 23 males and 12 females(males:females=1.92:1);there were 22 patients(62.80%)had injured history,2 smokers(5.71%)and 3 drinkers(8.57%);based on the tumor position,there were 19 patients occurred in femur(54.29%),6 patients occurred in tibia(17.14%),4 patients occurred in humerus(11.43%),6 patients(17.14%)occurred in other parts,such as pelvis,fibula,radius,scapula,foot,spine and ulna;during diagnosis,there were 6 patients(17.14%)had obvious metastasis;all the patients had noteworthy pathological types,13 patients was osteogenic osteosarcoma(37.14%),8 patients with chondrocytic osteosarcoma(22.86%),3 patients was fibrocytic type(8.57%),4 patients with other types(11.43%),and 7 patients with mixed type(20.00%).Most of the patients come from the northern area.Conclusion:This study reported the epidemiology features and clinical characteristics of 35 osteosarcoma patients who were diagnosed and treated in out hospital.Present study could provide the demographic characteristics and clinical characteristics of osteosarcoma patients in the northern area of China.PART 2Correlation analysis between AEG-1 gene polymorphisms and osteosarcoma susceptibilityObjective:The objective of this study was to explore the relationship between single nucleotide polymorphisms(SNPs)of the astrocyte elevated gene-1(AEG-1)gene(rs16896059 and rs1311)and osteosarcoma(OS)susceptibility in Chinese Han population.Methods:Representativeness of the case and control groups were evaluated by Hardy-Weinberg equilibrium(HWE).Genotype and allele frequencies of the two polymorphisms were obtained by direct calculation.Differences of the genotyes and alleles of these polymorphisms were assessed by Chi-square test.Relative risk of OS was represented by odds ratios(ORs)with 95%confidence intervals(CIs).Results:GG,GA and AA genotype frequencies of AEG-1 gene rs16896059 polymorphism were 62.8%,34.3%and 2.9%in osteosarcoma patients,57.1%,37.1%and 5.7%in healthy controls,respectively.Frequencies of rs16896059 polymorphism AA genotype was significantly higher in control group than that in case group when compared with the GG genotype(P=0.022),it indicated that AA genotype was closely associated with decreased osteosarcoma risk(OR=0.375,95%CI=0.043-0.891).Frequencies of AEG-1 gene rs16896059 polymorphism A and G alleles were respectively 80.0%and 20.0%in case group,72.4%and 27.6%in control group.Significantly higher rs16896059 A allele frequencies in control group suggested that this allele was distinctly correlated with decreased osteosarcoma risk(P=0.038,OR=0.551,95%CI=0.387-0.972).TT,CT and CC genotype frequencies of AEG-1 gene rs1311 polymorphism were 54.3%、34.3%and 11.4%in osteosarcoma patients,55.2%、39.5%and 5.3%in healthy controls.Frequencies of rs1311 T and C alleles were respectively 71.4%and 28.6%in case group,75.0%and 25.0%in control group.However,all of the genotypes and alleles of rs1311 polymorphism had no obvious difference between case and control groups(P>0.05),demonstrated that rs1311 polymorphism did not relate to the osteosarcoma susceptibility.Conclusion:AEG-1 gene rs16896059 polymorphism act as a protect factor for the occurrence of osteosarcoma.But rs1311 had no significant association with the osteosarcoma risk.Further studies with enlarged sample size is necessary to performed in the future to certify present findings.