INVERSE CORRELATION BETWEEN EXPRESSION OF HLA-B AND c-myc IN UVEAL MELANOMA

HLA class I is expressed in 75–85 per cent of uveal melanoma and cytoplasmic c‐myc expression has been reported in 78 per cent of uveal melanoma. In skin melanoma, an inverse relationship has been observed between HLA class I expression and c‐myc. The purpose of this study was to determine whether a similar correlation occurred between high expression of c‐myc and low expression of HLA class I in uveal melanoma. The expression of c‐myc, HLA‐A, and HLA‐B was determined by immunohistochemistry on formalin‐fixed and paraffin‐embedded sections of 30 uveal melanomas. Cell cultures from four primary uveal melanomas (lines 92‐1, MEL 202, OCM‐1, and EOM‐3) and one uveal melanoma metastasis (line OMM‐1) were tested for mRNA levels of c‐myc and HLA‐A and HLA‐B in Northern blot assays. The high level of expression of cytoplasmic c‐myc was significantly correlated with low expression of HLA‐B (P=0·03) and vice versa. High expression of HLA‐B was significantly correlated with the presence of epithelioid cells (P=0·004). The inverse correlation observed between c‐myc and HLA‐B expression is similar to previous observations in cutaneous melanoma. By downregulating HLA‐B expression, c‐myc may influence the immune response in uveal melanoma. Tumours containing epithelioid cells showed a significantly higher expression of HLA‐B than tumours of the spindle cell type. © 1997 by John Wiley & Sons, Ltd.