Promoter Methylation Of RASSF1A Gene In Meibomian Gland Carcinoma And Protein Expression

Object: The meibomian gland carcinoma(meibomian gland carcinoma, MGCA) which are not many reports on foreign literature, belongs to the high malignant tumor. Its incidence of second only to basal cell carcinoma is about 32.7% in Chinese eyelid malignant tumor.And there is a growing trend in the world. It has biological characteristics of infiltrating and aggressive, has obvious clinical misdiagnosis easily, recurrence and metastasis, and treatment is very difficult, serious threat to the patient’s vision and life.To reduce the morbidity and mortality of meibomian gland carcinoma, must attach importance to the research of its pathogenesis due to early diagnosis.In addition to the sequence of nucleotides of DNA change can affect the development of tumor, epigenetic mechanisms with more attention paid to the role in the tumor formation process, the change of the state of DNA methylation in tumor, reduced levels of methylation of overall and partial methylation levels, namely the tumor-suppressor genes with high repair gene methylation with reverse transcription transposons, cancer gene methylation, which indicates it can be used as a kind of new tumor formation sensitivity index, even applied to the prevention and treatment of tumor.RASSF1A is Dammann etc. in 2000, using the yeast two hybrid screening method, the chromosome 3 p21. 3 of the area to clone a new kind of Ras factor, it belongs to the family of RASSF1(Ras Association Domain family 1)(RASSF1A- RASSF1H) a subtype, subsequent research has shown that it is a new type of tumor suppressor gene, its inactivation can lead to human a variety of malignant tumors, and in human tumors, RASSFIA gene is rare mutations, promoter methylation play a major role in the RASSFIA expression.Since the pl6 gene RASSF1 A methylation in tumor is the highest level, one of the most widely gene, extensive research has shown that found in a wide variety of tumor RASSFIA high lack of expression and promoter region methylation, play an important role on the occurrence and development of tumor.So can think RASSF1 A gene methylation change can become a kind of important candidate early diagnosis of tumors.Methods:1 Immunohistochemistry method was used to examine the protein expression of RASSF1 A in 40 MGCA tumor tissues and corresponding normal tissues.2 Methylation specific PCR(MSP) method was used to examine the methylation status of RASSF1 A gene in 40 MGCA tissues and 40 normal tissues.3 SPSS13.0 was applied to analyze the results of experiments.Results:RASSF1A promoter methylation status: In 40 cases of meibomian gland carcinoma, 29 cases of cancer tissue occurred methylation of RASSF1 A gene promoter methylation,methylation rate is 72.5%(29/40); 40 cases of normal meibomian gland, 6 Cases of organizations have RASSF1 A gene promoter methylation, methylation frequency is 15%(6/40). Meibomian gland cancer gene promoter methylation of RASSF1 A was significantly higher than the normal meibomian gland, the difference was statistically significant(χ2 = 22.236, P = 0.000 <0.01). the methylation status of this locus was not associated with status of age(P>0.05), gender(P>0.05) and TNM stage(P>0.05). And it was not significantly related to status of pathological differentiation(P>0.05) and relapse(P>0.05).RASSF1A protein expression: 40 cases of meibomian gland carcinoma, 11 cases of RASSF1 A protein expression, the expression rate of 27.5%(11/40); 40 cases of normal meibomian gland RASSF1 A protein expression 100%(40/40). RASSF1 A protein expression in meibomian gland cancer rates were significantly lower than in normal meibomian gland, the difference was statistically significant(χ2 = 30.000, P = 0.000 <0.01). The protein expression of RASSF1 A was not associated with status of age(P>0.05), gender(P>0.05)and TNM stage(P>0.05). And it was not significantly related to status of pathological differentiation(P>0.05) and relapse(P>0.05).Conclusion : RASSF1 A hypermethylation and lower or loss of RASSF1 A protein expression were significantly occurred in meibomian gland carcinoma, it can be inferred:1 RASSF1 A gene promoter methylation may result in inactivation of the gene cause reduced or absent expression products and the closely related gene methylation, RASSF1 A gene promoter methylation of meibomian gland cancer pathogenesis.2 RASSF1 A protein expression decrease or loss on the incidence of meibomian gland cancer, played an important role.3 RASSF1 A is expected to as meibomian gland cancer molecular marker, so as to early diagnosis of meibomian gland cancer and provide the theoretical basis of biological targeted therapy.4 The methylation status of RASSF1 A had no association with age and gender of MGCA patients. And it was not significantly related to status of relapse, TNM stage and pathological differentiation, indicating that methylation of RASSF1 A may be not associated with the occurrence, development and infiltration of MGCA.But it was indicating that methylation of RASSF1 A may be associated with the occurrence of MGCA.