Expression And Clinical Significance Of DDMT1and PDCD4in Tongue Squamous Cell Carcinoma

Objectives:To study the expression of DNMT1and PDCD4in TSCC and in its adjacentnormal tissue, meanwhile to analyze the relationship between the expression levelsof the two proteins, and their relevance to some clinicopathologic parameters such asage, sex, type of tissue pathological differentiation, TNM staging, occurrence ofregional lymph node transfer and so on; to explore the roles of the two factors in theinitiation and progression of tongue squamous carcinoma, determine if theexpressions of the two proteins can serve as Biomarkers for the early diagnosis,treatment and clinical prognostic evaluation.Methods:Immunohistochemical Elivision two-step method was used to detect the DNMT1and PDCD4expression in TSCC and the corresponding adjacent normal tissue from40cases; SPSS17.0statistical software was employed to make statistical analysis ofthe results, so as to study DNMT1and PDCD4expression in TSCC andadjacent normal tissue, as well as their relevance to some clinicopath-ologic param-eters such as age, sex, type of tissue pathological differentiation, clinical stage,occurrence of regional lymph node transfer and so on.Results:1. The DNMT1expression in TSCC of29cases in the40cases was positive(positive rate:72.5%). While positive expression in the40cases correspondingadjacent normal tissues was only found in5cases (positive rate:12.5%). There wassignificant difference in the DNMT1protein expression between TSCC andnon-tumor tissue (P<0.05).2. The PDCD4expression in TSCC of12cases in the40cases was positive(positive rate:30%). While positive expression in the40cases correspondingadjacent normal tissues was found in31cases (positive rate:77.5%). There wassignificant difference in the PDCD4protein expression between TSCC andnon-tumor tissue (P<0.05). 3. The expression level of DNMT1protein in TSCC was associated with type oftissue pathological differentiation, occurrence of regional lymph node transfer andTNM staging (P<0.05) and not associated with the patient’s gender and age (P>0.05);4. The expression level of PDCD4protein in TSCC was associated withoccurrence of regional lymph node transfer and TNM staging (P<0.05) and notassociated with the patient’s gender, age and type of tissue pathological differentiation(P>0.05);5. Positive expression of the two proteins was found in5cases of40TSCCpatients, while negative expression was found in4cases. Speraman rank correlationanalysis was used to detect the negative correlation between the expression of the twoproteins in TSCC (r=－0.452，P<0.05).Conclusions:1. There is high DNMT1expr ession and low PDCD4expression in TSCC; theexpression of the corresponding non-tumor tissues of the two proteins are just on thecontrary, which suggest the close correlation between the expression changes of thetwo proteins and the occurrence and development of TSCC.2. The expression level of DNMT1protein in TSCC was associated with type oftissue pathological differentiation, occurrence of regional lymph node transfer andTNM staging (P<0.05) and not associated with the patient’s gender and age (P>0.05);while the expression level of PDCD4protein in TSCC was associated withoccurrence of regional lymph node transfer and TNM staging (P<0.05) and notassociated with the patient’s gender, age and type of tissue pathological differentiation(P>0.05).3. DNMT1is a key enzyme in DNA methylation, while PDCD4is a kind ofcancer suppressor gene. The expression of the two in TSCC shows the negativecorrelation (r=－0.452， P<0.05). DNA methylation is early events in thedevelopment of tumorigenesis, Excessive methylation can silence PDCD4geneexpression. In this study, we speculated that to higher related enzyme DNMT1expression of methylation by a reason or a via pathway, all the same increased theenzyme can induce PDCD4excessive methylation, it make the PDCD4genesilencing, protein expression reduced. Normal tongue tissue of oncogene and tumor suppressor gene expression in balance, while tumor-suppressor protein reduce canlead to the occurrence of tongue squamous carcinoma。It can be concluded thatDNMT1may cause the occurrence of tumor by negatively adjusting PDCD4geneexpression through a high level of methylation.