RESUMEN
It was well established that HPV infection, especially type 16 and 18 is the major cause of cervical cancer. Immune evasion of infected cells or tumor cells is also known as one of contributing factors of tumor development caused by down-regulation of MHC class I expression. The aim of this study is to investigate the level and pattern of MHC class I expression in 182 cervical cancerous tissues and 57 normal cervix using immunoperoxidase staining technique. Of 182 cervical cancerous tissues, 50 cases were classified as pre-cancerous lesions whereas, 132 cases were invasive cervical carcinoma. No significant association in grading or intensity of MHC class I was shown between patient and control group. Interestingly, the distribution pattern of MHC class I was significantly shown as non-surface presenting molecules accumulating in cytoplasm of cancerous tissues compared to normal cervix tissues with p-value \< 0.001 χ² test .This result indicates that tumor cells have lost their immune surveillance by reducing their antigen presenting MHC class I molecules at cell surface. Moreover, this alteration can be used as an early marker for cancer prognosis in pre-cancerous group. Therefore, the mechanism of the impairment in antigen presenting of MHC class I molecules should be investigated in further study.
RESUMEN
Cervical cancer is the most common cancer among women worldwide. Even though HPV infection is known as the major risk factor of cervical carcinogenesis, immune evasion of infected cells or tumor cells is also well established as the major contributing factors. Down regulation of MHC class I as well as the presence of non-surface presenting MHC class I molecules have been previously reported. Our aim of this study is to investigate the expression level of tapasin protein which is one of the MHC class I antigen processing proteins in various stages of cancerous tissues. Seventy nine dysplasia and 49 cases of cervical cancer and 49 normal cervix from myoma patients as control were included in this study. The association between the expression level and disease progression was analyzed using χ2 for trend. The reduction of tapasin expression is significantly associated with respect to the progression of staging in both dysplasia and cervical cancer group (p=0.001; χ2 for trend). In conclusion, our study illustrates that the reduction in tapasin expression might exert as one of the mechanism leading to the impairment of antigen presenting of MHC class I in cancerous tissues. Therefore, tapasin staining might be useful as an early prognostic marker in dysplasia. More antigen processing proteins should be also further investigated.