Abstract
Human telomerase reverse transcriptase (hTERT) is a critical factor in unlimited cell proliferation and immortalization, with numerous studies demonstrating that high expression of hTERT is a poor prognostic factor in various types of cancer. Ubiquitin-conjugating enzyme E2D 3 (UBE2D3) is a member of the E2 family, and participates in the ubiquitin proteasome pathway to regulate basic cellular activities, such as cell cycle control, the DNA damage response, apoptosis, and tumorigenesis. Our previous study initially determined that downregulation of UBE2D3 expression increases hTERT expression and cell proliferation, however, the association between the expression of these two proteins and their functions in cancer tissues remains unknown. Therefore, the protein expression levels of hTERT and UBE2D3 were evaluated in 150 esophageal cancer and 30 adjacent healthy tissue samples by performing immunohistochemical analysis. Concurrently, the clinicopathological data of the enrolled patients were obtained to allow correlation analysis. It was identified that the expression of hTERT in the esophageal cancer tissues was significantly higher compared with that of the adjacent tissues (P=0.015), however, the expression of UBE2D3 was significantly lower in esophageal cancer tissues than the adjacent tissues (P=0.001). Additionally, the study demonstrated that hTERT was significantly upregulated in poorly-differentiated, advanced tumor-node-metastasis (TNM) stage cancer tissues (P<0.05 for all), however, UBE2D3 expression was downregulated in poorly-differentiated, lymph node invaded cancer tissues and recurrent cases. It was also identified that traditional factors, including tumor location, T stage, lymph node status, TNM stage, and molecular factors of hTERT and UBE2D3, were significantly associated with overall survival time (P<0.05 for all). Furthermore, UBE2D3, lymph node status and tumor location were independent prognostic factors for esophageal cancer in multivariate analysis. Most notably, hTERT and UBE2D3 expression were negatively correlated with each other. In conclusion, the findings of the present study indicated that hTERT and UBE2D3 proteins appear to be involved in the development of esophageal cancer, that UBE2D3 may a positive prognostic factor for esophageal cancer, and that UBE2D3 and hTERT expression levels are inversely correlated.