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Expression of manganese superoxide dismutase in esophageal and gastric cancers
1Second Department of Surgery, Kinki University, School of Medicine, Osaka-Sayama, Osaka, Japan.
Abstract:
The tumor-killing activity of radiotherapy and chemotherapy for cancer is closely associated with the production of active oxygen, and the relation between therapeutic resistance and active oxygen scavengers produced by the tumor itself is gaining more attention. It is considered that manganese superoxide dismutase (MnSOD) protects host cells from oxidative stress, in synergy with other antioxidant enzymes. In this study, we used a quantitative polymerase chain reaction assay to measure MnSOD mRNA in resected specimens from patients with esophageal and gastric cancers. In both esophageal and gastric cancers, the level of MnSOD mRNA was significantly elevated in cancer tissue compared to non-cancer tissue (P < 0.01). In gastric cancer tissue, the MnSOD mRNA level was significantly higher than in esophageal cancer tissue (P < 0.01). The significance of MnSOD in cancer tissue was investigated further by measuring MnSOD content in resected specimens using an enzyme-linked immunosorbent assay, and by examining its location by an immunohistochemical method. Upregulation of MnSOD in cancer tissue most likely serves as a protective mechanism against anti-cancer therapies known to produce superoxide radicals as a key component of their tumor-killing activity.
Insights
Manganese superoxide dismutase (MnSOD) is elevated in esophageal and gastric cancers, potentially protecting tumors from oxidative stress caused by cancer therapies. This upregulation may contribute to therapeutic resistance.
Area of Science:
- Oncology
- Biochemistry
- Molecular Biology
Background:
- Radiotherapy and chemotherapy efficacy relies on active oxygen production.
- Tumor-produced active oxygen scavengers are increasingly linked to therapeutic resistance.
- Manganese superoxide dismutase (MnSOD) is a key antioxidant enzyme protecting cells from oxidative stress.
Purpose of the Study:
- To quantify manganese superoxide dismutase (MnSOD) mRNA levels in esophageal and gastric cancer tissues.
- To investigate the role of MnSOD in cancer tissue and its potential link to therapeutic resistance.
Main Methods:
- Quantitative polymerase chain reaction (qPCR) assay to measure MnSOD mRNA.
- Enzyme-linked immunosorbent assay (ELISA) to measure MnSOD protein content.
- Immunohistochemical analysis to determine MnSOD location within tissues.
Main Results:
- MnSOD mRNA levels were significantly elevated in both esophageal and gastric cancer tissues compared to non-cancerous tissues (P < 0.01).
- Gastric cancer tissues exhibited significantly higher MnSOD mRNA levels than esophageal cancer tissues (P < 0.01).
- Further analysis confirmed MnSOD upregulation in cancer tissues.
Conclusions:
- Elevated MnSOD in esophageal and gastric cancers likely represents a protective mechanism against anti-cancer therapies.
- This upregulation may contribute to tumor resistance to therapies that generate superoxide radicals.