Expression of interleukin-8 detected by in situ hybridization correlates with worse prognosis in primary cutaneous melanoma

Previous in vitro studies have demonstrated that endogenously produced huma n interleukin-8 (IL-8) can act as an important growth factor for human mela noma cells in vitro. The present study, has investigated whether IL-8 mRNA expression in primary melanomas may be of prognostic relevance with regard to melanoma progression and metastatic spread. In order to evaluate the cli nical significance of IL-8 mRNA expression of melanoma cells ill vivo, 59 m elanocytic tissue specimens (37 primary melanomas and 22 melanocytic naevi) were studied using a semiquantitative in situ hybridization technique. Sig nificant mRNA expression of IL-8 was found in 59 per cent (22/37) of melano mas, In 19 per cent (7/37) of the malignant melanomas, additional hybridiza tion signals were noted within keratinocytes of the overlying epidermis, In contrast, paralesional normal-appearing epidermis and melanocytes in non-m alignant lesions (melanocytic naevi) showed no IL-8 mRNA, Analysis of the r elationship between IL-8 expression and clinico-histopathological features showed a significant association between IL-8 mRNA expression and the histo logical melanoma subtype (IL-8 mRNA: 14/19 in superficial spreading melanom a versus 4/12 in nodular melanoma, p<0.05). Furthermore, IL-8 expression in primary tumours could be correlated with the patients' clinical course, wi th time to progression being significantly reduced in primary tumours expre ssing IL-8 in either the tumour cells or keratinocytes of the overlying epi dermis, These results demonstrate for the first time that IL-8 expression, as detected by in situ hybridization in primary tumours, may serve as a sig nificant prognostic factor for tumour progression in human malignant melano ma, Copyright (C) 1999 John Wiley & Sons, Ltd.