Expression pattern of sonic hedgehog and effect of topical mitomycin C on its expression in human ocular surface neoplasms

Abstract

Purpose: To examine if the cells of human ocular surface neoplasms express sonic hedgehog (Shh) and the effects of topical mitomycin C on its expression.

Methods: Conjunctival tissues obtained from two normal subjects, two patients with squamous cell carcinoma of the ocular surface (conjunctiva), and one patient with ocular epithelial dysplasia were used in this study. Histological sections were processed for light microscopic immunohistochemical analysis for Shh.

Results: Faint immunoreactivity for Shh was detected in basal epithelial cells of limbus, bulbar, and palpebral conjunctival epithelial cells. On the other hand, squamous cell carcinoma cells markedly expressed Shh with positive staining for Patched 1(Ptc), the cell surface receptor of Shh. Similar marked expression of Shh was detected in the patient with ocular epithelial dysplasia, and this Shh expression was almost eliminated following topical mitomycin C treatment. A cell culture experiment was conducted to examine the effect of mitomycin C on Shh expression in a cultured squamous cell carcinoma cell line.

Conclusions: Conjunctival epithelium constitutively expresses a low level of Shh, and its expression increases during malignant conversion of epithelial cells. Reduction of Shh expression might be involved in the therapeutic efficacy of topical mitomycin C for ocular surface epithelial neoplasms.