Aim: Esophageal cancer remains a significant health problem worldwide. It is important to investigate alterations in expression of retinoic acid receptor-β, p53 and Ki67 proteins in esophageal carcinogenesis. Methods: To find biomarkers for early identification of esophageal cancer, we analyzed the retinoic acid receptor-β, p53 protein and the proliferation marker Ki67 in surgical specimens of normal, mildly, and severely dysplastic and malignant esophageal tissues by in situ hybridization of RNA and immunohistochemistry. Results: RAR-β was expressed in 94.3% (33/35) of normal mucosae, 67.8% (19/28) of the mild, 58.1% (18/31) of the severe lesions and 53.2% (116/218) of tumor samples. RAR-β mRNA was expressed in 62.7% (42/67), 55.1% (43/78) and 29.2% (7/24) of well, moderated and poorly differentiated SSCs. The p53 and Ki67 proteins were 5.9% (2/34) of the normal mucosa. P53 and Ki67 stained positively in 10.7% (3/28) and 21.4% (6/28) of mild dysplasia, and 51.6% (16/31) and 58.1% (18/31) of severely dysplasia respectively. Samples from esophageal cancer showed no higher levers of p53 and Ki67 expression than seen in severely dysplastic lesions. There was significant difference of RAR-β, p53 and Ki67 expression between normal mucosa and dysplastic tissue or esophageal cancer. Conclusion: Loss of RAR-β expression and accumulation of p53 and Ki67 proteins may serve as biomarkers for early identification of esophageal cancer in the high-risk populations.
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