Differential expression of telomerase reverse transcriptase in chronic human skin ulcer induced by radiation and mechanism of cancer transformation and poor healing

AIM:To study the expression of the catalytic subunit of telomerase, telomerase reverse transcriptase(TRT) and explore the possible relationship between the TR T and cancer transformation or poor healing in radiation-induced chronic human skin ulcer.METHODS:Rabbit antibody to human TRT and SP immunohistochemical metho d were used to detect TRT expression in 24 cases of formalin-fixed,paraffin-em beded chronic human skin ulcer tissues induced by radiation, 5 cases of normal s kin,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 ob served almost always strongly positive in the cytoplasm and nucleus of squamous epithelial cells of epidermis but negatively in the endoepithelial cells of capi llaries 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 e xpression in the epidermis could be involved in the cancer transformation from c hronic radiation ulcer to squamous carcinoma, whereas the negative or weak TRT e xpression in the capillaries, small blood vessels and fibroblasts of dermis migh t be responsible for the poor healing of chronic ulcers induced by radiation, ca used by sclerosis of small blood vessels and lack of granulation tissue consisti ng of capillaries and fibroblasts.