The relation between c-myc expression and interferon sensitivity in uveal melanoma

Background/aim: Interferons (IFN) are currently being used to treat melanoma, including some patients with uveal melanoma. IFN is thought to inhibit tumour growth through downregulation of the c-myc oncogene; the overexpression of which has been shown to be associated with resistance in cell lines. The aim of this study was to investigate the relation between c-myc gene expression and IFN sensitivity in a series of uveal melanomas in a short term chemosensitivity assay. Methods: Tumours from 45 patients with uveal melanoma who had undergone enucleation were studied. The ATP chemosensitivity assay was used to study sensitivity to IFN-α-2b in freshly isolated cells from each tumour. Flow cytometry was used to assess c-myc expression in formalin fixed material from the primary specimens. Results: There was a wide range of IFN sensitivity between the specimens whereas c-myc expression was universal and present in 80% of the tumour cells in 80% of the specimens. Higher c-myc expression was associated with IFN-α resistance as measured by the maximum percentage of inhibition (p = 0.05) and there was a trend with the IFN sensitivity index (p = 0.07). Conclusions: These results demonstrate that tumours with high c-myc expression are also associated with IFN resistance. Future research is required to explore the potential of c-myc gene manipulation combined with IFN therapy.