HLA-G expression in basal cell carcinomas of the skin recurring after radiotherapy

Abstract

Basal cell carcinoma (BCC) of the skin represents the most common malignancy in the fair‐skinned population worldwide. HLA‐G is one of the molecules implicated in immunotolerance. To investigate the role of HLA‐G in recurring BCCs, we constructed a tissue microarray containing 38 primary BCCs that underwent radiotherapy and 14 secondary BCCs recurring on the primary site after radiotherapy, and evaluated the HLA‐G protein expression by immunohistochemistry. The HLA‐G protein was most frequently expressed in aggressive sclerosing BCCs. Nodular BCC demonstrated the strongest HLA‐G expression. Interestingly, tumor infiltrating mononuclear cells (TIMC) expressed the HLA‐G molecule in BCCs that showed no recurrence. After comparing primary BCCs and BCCs relapsed after radiotherapy, we observed decreased HLA‐G expression on tumor cells and the loss of HLA‐G expression on TIMC in relapsed BCCs. After radiotherapy, immunobiology of BCC may change resulting in the down‐regulation of HLA‐G expression on tumor and on tumor‐infiltrating cells.