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Role of tissue antioxidant defence in thyroid cancers
1Radiation Medicine Centre (BARC), Tata Memorial Centre Annexe, Parel, Bombay, India.
Abstract:
Reactive oxygen species (ROS), consisting mainly of superoxide, hydrogen peroxide and hydroxyl radical, have been implicated in many diseases including cancer. ROS have been known to play an important role in the initiation and promotion of multistage carcinogenesis. The cellular antioxidant defence plays a crucial role in neoplastic disease. However, very little is known about the tissue antioxidant defence in thyroid cancers. We therefore undertook a study to assess the role of ROS in the pathogenesis of thyroid cancers. Our samples consisted of post-operated thyroid tissues (normal, goiters, follicular adenomas, follicular carcinomas and papillary carcinomas). The parameters studied were lipid peroxidation (LP), antioxidant enzymes--superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)--and non-protein thiols (GSH). Compared to normal thyroid no changes were seen in goiters. LP was significantly higher in adenomas (16%) and carcinomas (60-69%). SOD was decreased by 15% in adenomas while in carcinomas it increased by 9-12%. GPx was raised in carcinomas by 10-21%. Follicular carcinomas showed a 4% increase in CAT activity while GSH was raised in adenomas and papillary carcinomas by 17%. Thus, in adenomas (initial stage) involvement of superoxide radicals and in carcinomas (later stage) hydrogen peroxide and, possibly, hydroxyl radical involvement cannot be ruled out. These ROS may be responsible for elevated LP observed in adenomas and carcinomas.
Insights
Reactive oxygen species (ROS) are linked to thyroid cancer development. Antioxidant levels and lipid peroxidation change significantly in thyroid adenomas and carcinomas, suggesting ROS involvement in pathogenesis.
Area of Science:
- Biochemistry
- Oncology
- Pathology
Background:
- Reactive oxygen species (ROS) are implicated in various diseases, including cancer.
- ROS play a role in multistage carcinogenesis, and cellular antioxidant defense is crucial in neoplastic diseases.
- Limited knowledge exists regarding tissue antioxidant defense in thyroid cancers.
Purpose of the Study:
- To investigate the role of ROS in the pathogenesis of thyroid cancers.
- To assess antioxidant status and lipid peroxidation in different thyroid tissue types.
Main Methods:
- Analysis of post-operative thyroid tissues: normal, goiters, follicular adenomas, follicular carcinomas, and papillary carcinomas.
- Measurement of lipid peroxidation (LP), antioxidant enzymes (superoxide dismutase - SOD, catalase - CAT, glutathione peroxidase - GPx), and non-protein thiols (GSH).
Main Results:
- Lipid peroxidation (LP) was significantly elevated in adenomas and carcinomas compared to normal thyroid tissue.
- Superoxide dismutase (SOD) activity decreased in adenomas but increased in carcinomas.
- Glutathione peroxidase (GPx) and catalase (CAT) activities were elevated in carcinomas, while GSH levels increased in adenomas and papillary carcinomas.
Conclusions:
- The findings suggest the involvement of superoxide radicals in early-stage adenomas and hydrogen peroxide/hydroxyl radicals in later-stage carcinomas.
- Elevated ROS may contribute to the increased lipid peroxidation observed in thyroid adenomas and carcinomas.
- These alterations in antioxidant defense mechanisms highlight the potential role of ROS in thyroid cancer progression.