Abstract: Objective To observe the expressions of two inhibitors of apoptosis proteins （IAPs）, survivin and livin, as well as their related factors, Bcl-xl and Caspase-3 in mycosis fungoides （MF）, along with the effects of NB-UVB irradiation on them. Methods Totally, 30 patients with MF （5 at erythema stage, 16 at plaque stage and 9 at tumor stage） collected from 1995 to 2007 were included into this study. Of the patients, 11 received the treatment with NB-UVB irradiation. Tissue samples were resected from 30 untreated patients, 11 irradiated patients and 10 normal human controls. SABC immunohistochemistry （IHC） stain was used to evaluate the protein expression of survivin, livin, Bcl-xl and caspase-3 in these samples. Also, the mRNA expression of these four factors and cell apoptosis were detected by hybridization in situ （ISH） and terminal deoxynucleotidyl transferase （TdT）-mediated dUTP-fluorescence nick end labeling （TUNEL stain） respectively in the samples from 11 patients before and after NB-UVB irradiation. Results In samples of erythema-stage MF, plaque-stage MF and tumor-stage MF, the positivity rate was 40.00%, 75.00%, 77.78% for survivin respectively, 60.00%, 68.75%, 88.89% for Bcl-xl respectively, 40%, 25%, 44.44% for livin respectively, and 60.00%, 68.75%, 88.89% for caspase-3 respectively. No expression of survivin or Bcl-xl was observed in normal controls, while the expression of livin and caspase-3 was similar between MF and control samples. After NB-UVB irradiation, an increase was noticed in the count of apoptosis cells （t = 6.49, P < 0.001） and mRNA expression of caspase-3 （P < 0.10）, while a decrease in the mRNA expression of survivin and Bcl-xl in MF tissues, and no changes occurred to the mRNA expression of livin （P > 0.10）. Conclusions Survivin, Bcl-xl and caspase-3 may be associated with the pathogenesis of MF by regulating the cell apoptosis of T lymphocytes. NB-UVB could suppress the mRNA expression of survivin and Bcl-xl, lower the levels of IAP, enhance the transcription of caspase-3, and accelerate the apoptosis of tumor cells, which may partly explain the mechanism of therapeutic effect of NB-UVB in MF.

Key words: mycosis fungoides, inhibitor of apoptosis protein, narrow-band ultra-violet B