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BackgroundThe risk of UV radiation (UVR)-induced non-melanoma skin cancer (NMSC) is dramatically increased in immunosuppressed organ transplant recipients compared to immunocompetent patients. In the skin, p53 up-regulated modulator of apoptosis (PUMA) is a central regulator of apoptosis in response to UVR damage and immune response regulation. Data on the expression of PUMA in patients with NMSC relative to immune status is limited ObjectivesTo study differences in the expression and distribution of PUMA in cutaneous SCC and BCC by immunohistochemistry between immunocompetent patients and organ transplant recipients, and the effect of CsA-containing immunosuppressive maintenance regimens on this expression. Materials & MethodsPUMA expression in SCC ( n = 34) and BCC ( n = 20) was analysed comparatively by immunohistochemical staining in matched cohorts of 27 immunocompetent patients and 27 organ transplant recipients ResultsSCC and BCC showed unequivocal positive PUMA expression, however, there was no significant difference in NMSC between organ transplant recipients and immunocompetent patients. A 17% reduction in staining score for PUMA in SCC, but not in BCC, of organ transplant recipients treated with a cyclosporin (CsA)−containing regimen was noted compared to organ transplant recipients without chronic CsA intake ( p = 0.0381) ConclusionPUMA expression in SCC, but not BCC, is significantly reduced by CsA-containing therapy, suggesting a disturbance of apoptosis by iatrogenic immunosuppression with a divergent impact on SCC and BCC.