Aim: Esophageal cancer remains a significant health problem worldwide. It is important to investigate alterations in expression of retinoic acid receptor-beta, p 53 and Ki67 proteins in esophageal carcinogenesis.
Methods: To find biomarkers for early identification of esophageal cancer, we analyzed the retinoic acid receptor-beta, p 53 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-beta 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-beta 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 p 53 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 p 53 and Ki67 expression than seen in severely dysplastic lesions. There was significant difference of RAR-beta p 53 and Ki67 expression between normal mucosa and dysplastic tissue or esophageal cancer.
Conclusion: Loss of RAR-beta expression and accumulation of p 53 and Ki67 proteins may serve as biomarkers for early identification of esophageal cancer in the high-risk populations.