Promoter Methylation of the CDH-13 Gene in the Oral Squamous Cell Carcinoma

ABSTRACT

CDH-13(T-cadherin), which is one of a kind among the 20 cadherins, can be found mainly in wall of aorta, neuron, spleen, blood vessel etc. It is also called H-cadherin. This structural difference can explain that CDH-13 is thought to play a key role in maintaining mutual relation between extra and intra-cellular environment rather than in cell adhesion. The main function of CDH-13 is to participate in blood vessel function. Additionally, it is known to regulate cell growth and cell contact inhibition. When cells are proliferating, cell surface perceives other cells so that substance such as CDH-13 can inhibit their growth or proliferation resulting in homeostasis without endless proliferation or invasion of connective tissue boundaries. However, tumor cell itself appears to be different from normal cells' growth, invasion or transmission. Therefore, it can be diagnosed that these characteristics are closely related to expression of CDH-13 in tumor cells. This study is to investigate expression of CDH-13 in SCC and its correlation with promoter methylation. 20 of tissue species for the study are excised and gathered from 20 patients who are diagnosed as SCC in department of OMS, dental hospital, dankook university. To find development of CDH-13 in each tissue samples, immunohistochemical staining, RT-PCR gene analysis and methylation specific PCR are processed. The results are as follows. 1.Immunohistochemical staining: In normal oral squamous epithelial tissue, strong expression of CDH-13 was found in cell plasma membrane of basal cell layer. On the other hand, in case of low-differentiated oral SCC, development of CDH-13 was hardly seen. 2.The development of CDH-13 gene: In 9 of samples, expression of CDH-13 gene could be seen and 2 of them showed low expression compared to the others. And rest of the 11 samples showed no expression of CDH-13 gene. 3.Methylation of CDH-13 gene: Among 9 samples which expressed CDH-13 gene, 7 of them showed unmethylation. In addition, among 11 samples without CDH-13 gene expression, 10 showed methylation. According to the results stated above, promoter methylation were found in 13 samples(65%) among 20 of oral SCC samples. In low-differentiated SCC, suppression of gene expression could be seen accompanying promoter methylation. These phenomenon of gene expression was proved by immunohistochemical investigation. Finally, for development of oral SCC, conclusions can be made that suppression of CDH-13 played a main role and suppression of gene expression was originated from promoter methylation. Considering this, it is expected that suppression of CDH-13 from promoter methylation to be utilized as a good diagnostic marker of oral SCC.