The Methylation Status Of CpG Island In The Promoter Region And Proteins Expression Of NDRG1,NDRG2in Laryngeal Squamous Cell Carcinoma

Objective: The carcinoma of larynx is one of the malignant neoplasmin otolaryngology and head and neck surgery, accounting for1%-5%inthe malignant tumor of human body, with increasing tendency in morbility.90%of laryngeal carcinoma belong to laryngeal squamous cellcarcinoma(LSCC). Its progression and development involve genetics andepigenetics. More and more attention were given by us to study thepathogenesis in molecular level. Recently, the DNA methylation has becomethe focus. As the candidate tumor suppressor gene, the roles of NDRG1andNDRG2gene are still unknown. We investigate the hypermethylation andproteins expression of NDRG1and NDRG2of laryngeal carcinoma, andhope to found some beneficial information for theory research and clinicalwork.Methods:1The methylation specific PCR(MSP) method was used to examine themethylation status of the5'CpG island of NDRG1and NDRG2gene in45specimens of LSCC,18specimens of adjacent non-neoplastic tissue ascontrol.2Immunohistochemistry was employed to measure the protein expressionof NDRG1and NDRG2in45specimens of laryngeal squamous cellcarcinoma (LSCC)tissue,18specimens of adjacent non-neoplastic tissue ascontrol.3Statistics analysis: SPSS13.0was applied to analyze the results ofexperiment, and P<0.05was considered as statistical significantance.P<0.01indicating very significant difference.Results: 1The study result of NDRG11.1Positive rate of NDRG1gene methylation and relation with clinicalparameterPositive rate of NDRG1gene methylation in LSCC tissue and adjacentnon-neoplastic tissue were66.7%(30/45) versus33.3%(6/18). There wassignificant difference between the two groups(P<0.05). Positive rate ofNDRG1gene methylation in LSCC tissue was correlated with lymph nodemetastasis and clinical stage (P<0.05), but it wasn't correlated withpathological grading, patients' clinical classification, tumor size, smokinghistory, age and sex (P>0.05).1.2Protein expression of NDRG1and relationship with clinical parameterImmunohistochemistry was employed to measure the proteinexpression of NDRG1gene in45specimens of LSCC tissue and18specimens of adjacent non-neoplastic tissue. The positive protein expressionrate of NDRG1in LSCC tissue was37.8%(17/45), while that in the adjacentnon-neoplastic tissue was88.9%(16/18). There was very significantdifference between the two groups (P<0.01). Protein expression of NDRG1was correlated with lymph node metastasis and clinical stage (P<0.05), butit wasn't correlated with pathological grading, patients' clinicalclassification, tumor size, smoking history, age and sex (P>0.05).1.3The relationship between hypermethylation of NDRG1gene promoterand the protein expression of NDRG1The lower protein expression of NDRG1were26specimens in30cases methylation of NDRG1gene. There were significant negativecorrelation between the two groups (r＝-0.713, P<0.01).2.1Positive rate of NDRG2gene methylation and relation with clinicalparameterPositive rate of NDRG2gene methylation in LSCC tissue and adjacentnon-neoplastic tissue were53.3%(24/45) versus22.2%(4/18). There wassignificance difference between the two groups (P<0.05). Positive rate ofNDRG2gene methylation in LSCC was correlated with lymph node metastasis and clinical stage (P<0.05), but it wasn't correlated withpathological grading, patients' clinical classification, tumor size, smokinghistory, age and sex (P>0.05).2.2Protein expression of NDRG2and relation with clinical parameterImmunohistochemistry was employed to measure the proteinexpression of NDRG2gene in45specimens of LSCC tissue and18specimens of adjacent non-neoplastic tissue. The positive expression rate ofNDRG2in LSCC tissue was33.3%(15/45), while that in the adjacentnon-neoplastic tissue was83.3%(15/18). There was very significantdifference between the two groups (P<0.01). Protein expression of NDRG2was correlated with lymph node metastasis and clinical stage (P<0.05), butit wasn't correlated with pathological grading, patients' clinicalclassification, tumor size, smoking history, age and sex (P>0.05).2.3The relationship between hypermethylation of NDRG2gene promoterand the protein expression of NDRG2The lower expression of NDRG2protein were21specimens in24cases methylation of NDRG2gene. There were significant negativecorrelation between the two groups (r＝-0.472, P<0.01).Conclusions:1The hypermethylation and the lower protein expression of NDRG1,NDRG2may be related with oncogenesis of LSCC.2The hypermethylation of NDRG1and NDRG2in LSCC tissue werecorrelated with lymph node metastasis and clinical stage, which indicatedthat the hypermethylation of NDRG1and NDRG2gene may be participatedin the progression and metastasis of LSCC.3The lower expression of NDRG1and NDRG2protein in LSCC tissuewere correlated with lymph node metastasis and clinical stage, indicatingthat the lower expression of NDRG1and NDRG2protein may be contributeto the progression and metastasis of LSCC.4Both the NDRG1and NDRG2gene are hypermethylation and lowerprotein expression in LSCC tissue, indicating that the aberrant methylation of NDRG1and NDRG2gene is one of the mechanism of reduced and lossprotein expression of NDRG1and NDRG2. The hypermethylation and thelower expression of NDRG1, NDRG2gene may cooperative participated inthe progression and metastasis of LSCC, and the NDRG1and NDRG2genemay educe the function as tumor suppressor.