Purpose: The aim of this study is to investigate whether there are any abnormalities in the in vivo expression of retinoid acid receptors (RAR-alpha, RAR-beta and RAR-gamma) and retinoid X receptors (RXR-alpha, RXR-beta and RXR-gamma) in sebaceous cell carcinoma.
Methods: Expression of retinoid receptors in paired specimens of cancerous tissues (n = 10) and adjacent normal tissues (n = 10) from 10 patients with sebaceous cell carcinoma was studied immunohistochemically by using anti-retinoid receptor antibodies.
Results: In eight of the 10 normal tissue samples, all six receptors were expressed. In the other two samples, all receptors were expressed except RAR-gamma (one sample) or RXR-gamma (two samples). Five tumours (50%) lacked RAR-alpha; RAR-alpha expression was lower in tumours than in normal tissues in eight of 10 cases. RAR-beta was expressed in the cytoplasm of nine of 10 tumours; RAR-beta expression was at least as high in tumours as in normal tissue in eight of 10 cases. Two tumours lacked RAR-gamma; three tumours had lower RAR-gamma expression than paired normal epithelium; four had the same RAR-gamma expression, and one had higher RAR-gamma expression. RXR-alpha expression was strong in all normal tissues and tumour samples. Ten tumours lacked RXR-beta and all 10 tumours lacked RXR-gamma expression.
Conclusions: Diminished RXR-beta and RXR-gamma expression might be related to the development of sebaceous cell carcinoma. Additional studies are required to establish whether the defects in RAR expression in sebaceous cell carcinoma might affect the potential response of this tumour to treatment with retinoids.