Expression of haem oxygenase-1 correlates with tumour aggressiveness and BRAFV600E expression in thyroid cancer

Aims: Haem oxygenase-1 (HO-1) is an inducible enzyme that participates in haem degradation. Recent studies have indicated that HO-1 activation may play a role in tumour development and progression. The aim of this study was to evaluate the expression of HO-1 in thyroid cancer and its clinicopathological significance. Methods and results: We observed up-regulation of HO-1 in papillary thyroid tumours in comparison with normal thyroid tissue. Immunohistochemical analysis revealed that 48% of papillary cancers and 36% of follicular cancers, but none of normal thyroid tissues, were positive for HO-1 expression. Among 129 differentiated thyroid cancers, HO-1 expression was associated with patient age (P = 0.001), TNM stage (P = 0.001), and Mayo Clinic metastasis, patient age, completeness of resection, local invasion and tumour size score (P = 0.001). BRAF(V600E) expression was evaluated immunohistochemically and validated by Sanger sequencing. There was a strong association between HO-1 and BRAF(V600E) expression in papillary cancers (P = 0.002). Conclusions: Overexpression of HO-1 in a subset of thyroid cancers is associated with tumour aggressiveness and BRAF(V600E) expression. HO-1 might have a potential role in prognosis and targeted treatment in patients with thyroid cancer.