The Expression Levels And Methylation Patterns Of ITGBL1 In Myeloid Malignancies And Their Clinical Signifinance

Objective Integrin beta-like 1(ITGBL1)gene is located at chromosome 13q33.1 and cloned from an osteoblast cDNA library.Although ITGBL1 gene is a member of the EGF-like protein family,it does not contain neither a transmembrane domain nor an RGD(arginyl-glycyl-aspartic acid)binding domain,which indicates that ITGBL1 gene may has its special functions which are different from integrin family.In recent years,increasing studies have shown that ITGBL1 plays an important role in tumor development.However,the expression levels and methylation patterns of ITGBL1 gene in myeloid malignancies and their clinical significance have not been reported yet.The purpose of this study was to investigate the expression levels and methylation patterns of ITGBL1 gene in myeloid malignancies.Methods1?Real-time quantitative PCR(RQ-PCR)was applied to explore the expression levels of ITGBL1 gene in bone marrow(BM)mononuclear cells in 36 normal controls,144 acute myeloid leukemia(AML)patients,60 chronic myeloid leukemia(CML)patients and 20 myelodysplastic syndrome(MDS)patients,and their clinical relevance was further analyzed.2?Methylation-specific PCR(RQ-MSP)and bisulphite sequencing(BSP)were applied to examine the methylation patterns of ITGBL1 gene in BM mononuclear cells in 29 normal controls,144 AML patients,60 CML patients,and 66 MDS patients and their clinical relevance was further analyzed.3?SPSS 20.0 software was used to analyze the correlation between ITGBL1 gene expression levels and methylation patterns in myeloid malignancies.Results Compared with control group,ITGBL1 gene showed different degrees of low expression and hypermethylation pattern in myeloid malignancies. 1.Expression level and methylation pattern of ITGBL1 in AML The ITGBL1 expression level was significantly lower in AML patients than that in control group(P=0.004).The blast counts in the ITGBL1 low expression group was significantly higher than that in the ITGBL1 high expression group(P=0.005).The frequency of favorable karyotype in the ITGBL1 low expression group was relatively lower(P=0.028).Morever,karyotype analysis showed that the incidence of t(15,17)was lower in ITGBL1 low expression group(P=0.001),while the incidence of normal karyotype was relatively higher(P=0.041).The complete remission(CR)rate and overall survival(OS)of patients with low expression of ITGBL1 in AML patients were significantly lower than those in patients with high expression(P=0.027 and P=0.016).The ITGBL1 methylation level was significantly higher in AML patients compared to the controls(P<0.001).In all cases of AML and non-acute promyelocytic leukemia(non-APL),the OS and leukemia-free survival(LFS)of patients with ITGBL1 hypermethylation were significantly shorter than those with ITGBL1hypomethylation(P=0.009 and 0.023;P=0.043 and 0.039).Cox multivariate analysis demonstrated that ITGBL1 hypermethylation was an independent risk factor for prognosis in all AML patients and non-APL patients(P=0.030 and P=0.020).Meanwhile,the ITGBL1 methylation levels of 11 patients with AML who received CR after induction therapy were significantly lower(P=0.001).According to the Spearman correlation analysis,ITGBL1 expression levels were negatively correlated with their methylation status in AML patients(R=-0.328,P=0.008).2.Expression level and methylation pattern of ITGBL1 in CML In CML patients,ITGBL1 gene expression levels were significantly decreased compared to the control group(P=0.031).Patients in the low expression group had lower platelet levels than those in the ITGBL1 high expression group(P=0.005).Furthermore,patients with low expression of ITGBL1 had higher BCR-ABL1 levels(P=0.067).According to the results of RQ-MSP,the methylation pattern of ITGBL1 gene in CML patients was hypermethylated compared to the control group(P=0.039).Clinical correlation analysis indicated that ITGBL1 hypermethylation patients had a lower tendency of platelet levels compared to the ITGBL1 hypomethylation group(P=0.021).According to the Spearman correlation analysis,the expression level of ITGBL1 gene was negatively correlated with its methylation pattern in CML patients(R=-0.35,P=0.04).3.Expression level and methylation pattern of ITGBL1 in MDS The expression level of ITGBL1 gene in MDS patients was markedly lower than that of the control group(P=0.037).In addition,compared to the control group,the methylation level of ITGBL1 gene was hypermethylated in MDS patients(P<0.001).Survival analysis found that the OS of the ITGBL1 hypermethylated group was significantly shorter than that of the ITGBL1 hypomethylated group(P=0.014).Cox multivariate regression revealed that the hypermethylation of ITGBL1 in MDS patients had a certain significance in affecting the prognosis evaluation of patients(P=0.084).Conclusions1.ITGBL1 low expression and hypermethylation are common molecular events in myeloid malignancies;2.ITGBL1 hypermethylation can be used as an independent risk factor in the prognosis evaluation of patients;3.In AML and CML patients,the expression level of ITGBL1 gene was negatively correlated with its methylation pattern.