Deficiency of Superoxide Dismutase in Endemic Goiter Tissue*

Abstract

Superoxide dismutase (SOD) activity and its concentration were measured in thyroid tissues obtained from patients with Graves' disease, Hashimoto's thyroiditis, differentiated thyroid cancer, and endemic goiter (before and after iodine supplementation) as well as in normal thyroid tissue (paranodular tissue) from patients with follicular adenomas. SOD activity was measured by pyrogallol assay in ethanol-chloroform extracts of the thyroid homogenates. The SOD concentration in the thyroid extract was measured as immunoreactive SOD by electroimmunoassay. Endemic goiter tissues (n = 10) contained significantly lower SOD activity [mean, 1.9 +/- 1.9 (+/- SD) vs. 7.5 +/- 3.9 ng purified SOD/micrograms DNA; P less than 0.02] and concentration (mean, 0.2 +/- 0.1 vs. 0.8 +/- 0.5 ng SOD/microgram DNA; P less than 0.01) compared with those of normal tissues. No other pathological thyroid tissues had such consistently low SOD levels. Lactate dehydrogenase activity, a marker of cytosolic enzyme, was not lower in endemic goiter tissues than in normal tissues, suggesting that both tissues possessed functioning cells capable of producing cytosolic enzyme. Thyroid tissue from endemic goiter patients previously treated with iodized oil injection also had low SOD activity and concentration. Western blot analysis indicated that SOD protein in the endemic goiter tissue did not differ from that in normal thyroid tissue. We conclude that there is deficiency of cytosolic SOD in endemic goiter tissue. Since the deficiency of cytosolic SOD causes more prolonged exposure to oxygen free radicals, the decrease in SOD might contribute to the degenerative changes frequently found in these tissues.

Starvation induced hypothyroidism involves perturbations in thyroid superoxide‐sod system in pigeons

“…TSH has been shown to stimulate its target gene expression [34][35][36]. Long-term starvation in pigeon is marked by the disruption in the homeostasis between oxidants and antioxidants in the thyroid gland, leading to a state of oxidative stress which may contribute to the degeneration of the gland structurally and physiologically [37][38][39]. The clinical significance of SOD in the thyroid has been suggested by Suguwara et al [37].…”

“…Long-term starvation in pigeon is marked by the disruption in the homeostasis between oxidants and antioxidants in the thyroid gland, leading to a state of oxidative stress which may contribute to the degeneration of the gland structurally and physiologically [37][38][39]. The clinical significance of SOD in the thyroid has been suggested by Suguwara et al [37]. They found a deficiency of cytosolic SOD in the tissues of patients with endemic goiter in Brazil and suggested that the decreased enzyme activity may cause degeneration of tissue, presumably due to prolonged exposure to oxygen free radicals.…”

Oxidant/antioxidant balance in patients with thyroid cancer

“…Sugawara et al 14 and Durak et al 15 showed that endemic goiter tissues contained significantly lower SOD activity and concentration compared with those of normal tissues. In various other thyroid disorders including thyroid cancer SOD also found to be low.…”

Immunohistochemical localization of copper-zing and manganese superoxide dismutases in diisopropanolnitrosamine-induced rat thyroid lesions.

“…This observation is compatible with the results of previous investigations employing biochemical measurements which indicated decreased or defective SOD activities in cancer tissue (20,22,25). It is interesting to postulate that decreased en- zymatic activity contributes to tumorigenesis through either a causative or promoting mechanism (15,16,19,24). The findings of this study added two important facts to previous biochemical results; 1) Mn-SOD was focally expressed in some malignant nodules, and 2) an appreciable amount of SODS was demonstrated in stromal mesenchymal cells such as inflammatory cells and fibroblasts within and/or outside the tumor tissue, and these SODS could not be distinguished by chemical analysis of tissue homogenates.…”

“…Only a few studies have been performed on SOD activity of thyroid tissue extracts from patients with endemic goiter (19) or malignant neoplasms (25). Although biochemical measurements of SODS in tissue extracts are important for estimating the contents of SODS in tissues, it is impossible to demonstrate the tissue distribution of SODs by this method, and SODS derived from infiltrating inflammatory cells or mesenchymal cells containing appreciable levels of SODS cannot be excluded from the determination.…”