Differential expression of telomerase reverse: Transcriptase in epidermis and small blood vessels may be involved in the mechanism of cancer transformation and poor healing in chronic human skin ulcer induced by radiation

Background: Raising activity of telomerase is an important characteristic of immortality of malignant tumor cells. The most important part of telomerase for its activity is the catalytic subunit, telomerase reverse transcriptase (TRT). Radiation-induced chronic skin ulcer is a problematic lesion in carcinogenesis and poor healing. Objective: To study the expression of the catalytic subunit of telomerase, telomerase reverse transcriptase (TRT) and explore the possible relationship between the TRT and cancer transformation or poor healing in radiation-induced chronic human skin ulcer. Methods: Rabbit antibody to human TRT and SP immunohistochemical method were used to detect TRT expression in 24 cases of formalin-fixed, paraffin-embeded chronic human skin ulcer tissues induced by radiation, 5 cases of normal skin, 2 of burnt skin, and 8 of carcinoma. Results: The TRT was detected positive in 14 of 24 (58.3%) chronic radiation ulcers, of which the strongly positive was 10 of 24 (41.7%) and the weakly positive 4 of 24 (16.7%); in 0 of 5 normal and 0 of 2 burnt skins; and in 8 of 8 (100%) carcinomas. The expression of TRT was observed almost always strongly positive in the cytoplasm and nucleus of squamous epithelial cells of epidermis but negatively in the endoepithelial cells of capillaries and small blood vessels, or weakly in the cytoplasm of smooth myocytes of media and fibroblasts, of dermis. Chronic inflammtory cells, such as plasma cells and lymphocytes also showed weakly positive for TRT. Conclusion: The strong TRT expression in the epidermis could be involved in the cancer transformation from chronic radiation ulcer to squamous carcinoma, whereas the negative or weak TRT expression in the capillaries, small blood vessels and fibroblasts of dermis might be responsible for the poor healing of chronic ulcers induced by radiation, caused by sclerosis of small blood vessels and lack of granulation tissue consisting of capillaries and fibroblasts.