Association of defective HLA-I expression with antigen processing machinery and their association with clinicopathological characteristics in Kazak patients with esophageal cancer.

BACKGROUND: It has been confirmed that defective expression of human leukocyte antigen class I (HLA-I) molecules can contribute to the immune evasion of cancer cells in some types of cancer. The aim of this study was to examine the expression of HLA class I antigen and the antigen-processing machinery (APM) components in esophageal squamous cell carcinoma (ESCC) and their role in high risk human papillomavirus (HPV) infection, and to analyze their association with histopathological characteristics in the Kazak ethnic group. METHODS: A total of 50 formalin-fixed, paraffin-embedded ESCC lesions were collected from the First Affiliated Hospital of Xinjiang Medical University, China. The expression levels of HLA-I antigen and APM components were determined by immunohistochemistry; the HPV DNA were detected using polymerase chain reaction (PCR). RESULTS: A high frequency of down-regulation or loss of expression of HLA and APM components were found in esophageal cancer in Kazak people. HLA-I, TAP1, CNX, LMP7, Erp57, Tapasin and ERAP1 were down-regulated in 68%, 44%, 48%, 40%, 52%, 32% and 20% of ESCC lesions then, respectively. The loss of expression of HLA-I antigen was significantly correlated with part of the APM components and positively correlated with high risk HPV16 infection. TAP1, CNX, LMP7, Erp57 and Tapasin loss were significantly associated with tumor grading, lymph node metastasis and depth of invasion (P < 0.05). CONCLUSION: Our results suggest that APM component defects are a mechanism underlying HLA-I antigen down-regulation in ESCC lesions, and indicate that the loss expression of HLA-I and APM components will become an important marker of ESCC and analysis of HLA-I and APM component expression can provide useful prognostic information for patients with ESCC from the Kazak ethnic group.