Immunohistochemical and mutational status of telomerase reverse transcriptase in conjunctival squamous cell carcinoma

Mutations in human telomerase reverse transcriptase (TERT) are associated with increased telomerase activity in cutaneous melanomas. Conjunctival squamous cell carcinoma, also referred to as ocular surface squamous cell carcinoma, is cancer on the surface of the eye. Recent studies have identified UV signat`ure mutations in TERT promoters in ocular melanoma and ocular surface squamous neoplasia. However, its immunohistochemical status has not been reported in ocular surface squamous cell carcinoma. This study aimed to explore the immunohistochemical and mutational status of TERT in ocular surface SCC.

The immunohistochemical expression of TERT and mutational status of TERT promoter was evaluated in 19 ocular surface squamous cell carcinoma cases. Conjunctival melanoma tissue was used as a positive control.

The cytoplasmic overexpression of TERT was detected in 11/19 (57%), and TERT promoter mutations were identified in 6/19 (31%) of ocular surface squamous cell carcinoma. Out of these, 66% had a C228T mutation, and 33% had a C250T mutation. The TERT expression was found to be associated with a high (≥T3) AJCC category (P = 0.023), and TERT immunoexpression was significantly correlated with reduced disease-free survival (P = 0.024, log-rank analysis) in ocular surface squamous cell carcinoma patients.

The present study demonstrates that TERT promoter mutations with UV signatures are frequent in ocular surface squamous cell carcinoma. The increased expression of TERT could be of biological significance in aggressive ocular surface squamous cell carcinoma.