15-lipoxygenase-2 expression in benign and neoplastic sebaceous glands andother cutaneous adnexa

15-Lipoxygenase-2 has a limited tissue distribution in epithelial tissues, with mRNA detected in skin, cornea, lung, and prostate. It was originally c loned from human hair rootlets. In this study the distribution of 15-lipoxy genase-2 was characterized in human skin using immunohistochemistry and in situ hybridization, Strong uniform 15-lipoxygenase-2 in situ hybridization (n = 6) and immunostaining (n = 16) were observed in benign cutaneous sebac eous glands, with expression in differentiated secretory cells. Strong 15-l ipoxygenase-2 immunostaining was also observed in secretory cells of apocri ne and eccrine glands. Variable reduced immunostaining was observed in skin -derived sebaceous neoplasms (n = 8), In the eyelid, Meibomian glands were uniformly negative for 15-lipoxygenase-2 in all cases examined (n = 9), and sebaceous carcinomas apparently derived from Meibomian glands were also ne gative (n = 12), The mechanisms responsible for differential expression in cutaneous sebaceous vs eyelid Meibomian glands remain to be established. In epidermis, positive immunostaining was observed in the basal cell layer in normal skin, whereas five examined basal cell carcinomas were negative. Th us, the strongest 15-lipoxygenase-2 expression is in the androgen regulated secretory cells of sebaceous, apocrine, and eccrine glands. This compares with the prostate, in which 15-lipoxygenase-2 is expressed ill differentiat ed prostate secretory cells land reduced in the majority of prostate adenoc arcinomas). The product of 15-lipoxygenasc-2,15-hydroxyeicosatetraenoic aci d, may be a ligand for the nuclear receptor peroxisome proliferator activat ed receptor-gamma, which is expressed in sebocytes, and contribute to secre tory differentiation in androgen regulated tissues such as prostate and seb aceous glands.