Expression of heat shock protein 47 in the fibrous tissue adjacent to mouse tumour subjected to photodynamic therapy

SummaryThe reaction of normal fibrous tissue adjacent to tumours subjected to photodynamic therapy (PDT) was investigated by assessment of the immunohistochemical expression of heat shock protein 47 (HSP47) and proliferating cell nuclear antigen (PCNA), as well as by immunoblot analysis of procollagen type I. PDT was administered to NR-S1 mouse squamous cell carcinoma or normal mouse skin. Each of four mice was investigated at several time points after receiving PDT. The levels of HSP47 expression were determined by computer-assisted image analysis. The expression of procollagen type I in the fibrous tissue adjacent to the tumours was examined by immunoblot analysis at intervals of 24 and 48 h after PDT. The expression of HSP47 was first detected 6 h post-PDT in the tumour-bearing mice, but no such expression was observed in the normal mice. It was also revealed that, after PDT, the fibroblast PCNA labeling indices at 24, 48, and 72 h were significantly higher in both the tumour-bearing and the normal mice than in the control animals that did not receive PDT. Furthermore, procollagen type I was detected in the fibrous tissue adjacent to the tumours at 24 and 48 h after PDT, but was not detected in the fibrous tissue adjacent to tumours of mice that did not receive PDT. Therefore, the present results suggest that PDT enhances the synthesis of collagen type I in the fibrous tissue adjacent to NR-S1 squamous cell carcinoma in mice, which contributes to the resultant encapsulation of such tumours.