Microsomal reductase activity in patients with thyroid neoplasms

Objective Cytochrome b5 reductase (CYB5R) and cytochrome P450 reductase (CYPOR) play an important role in cell metabolism; however, their role in thyroid hormonogenesis and carcinogenesis has not been studied. The activity of CYB5R correlates with metastasizing in breast cancer, but there are no similar studies for CYB5R and CYPOR for thyroid cancer. The aim was to assess the activity of CYB5R and CYPOR in thyroid tissues in benign and malignant thyroid neoplasms. Methods 36 patients with thyroid neoplasms participated in the study. The control euthyroid goiter group included 10 patients; the thyrotoxic nodular goiter group included 14 patients; the papillary thyroid cancer T1-2N0-1M0 (PTC) group included 12 patients. The activity of CYB5R and CYPOR was assessed with lucigenin-enhanced chemiluminescence stimulated by NADH and NADPH, respectively. Results The activity of CYB5R and CYPOR increased several times in thyrotoxicosis and approximately by an order of magnitude in some cases of PTC, but the activity change of CYPOR was more pronounced compared to CYB5R. For the PTC group, the subgroups with low and high activity of microsomal reductases were detected. Microsomal reductases in follicular adenoma was 2–4-fold less active compared to nontoxic goiter and the low-activity PTC group. Conclusions Activity of microsomal reductases varies in thyroid pathology and can serve as a diagnostic and prognostic parameter in papillary thyroid cancer.