Uterine fibroids are characterized by an impaired antioxidant cellular system: Potential role of hypoxia in the pathophysiology of uterine fibroids

Purpose: Fibroids are the most common smooth muscle overgrowth in women. This study determined the expression and the effect of hypoxia on two potent antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) on human fibroid cells. Methods: Immortalized human leiomyoma (fibroid) and myometrial cells were subjected to hypoxia (2 % O₂, 24 h). Total RNA and cell homogenate were obtained from control and treated cells; CAT and SOD mRNA and activity levels were determined by real-time RT-PCR and ELISA, respectively. Results: Fibroid cells have significantly lower antioxidant enzymes, SOD and CAT mRNA and activity levels than normal myometrial cells (p < 0.05). Hypoxia treatment significantly increased SOD activity in myometrial cells while significantly decreasing CAT activity in fibroid cells (p < 0.05). There was no significant difference in CAT mRNA levels or activity in response to hypoxia in myometrial cells. Also, there was no significant difference in SOD mRNA levels in response to hypoxia in myometrial cells. Conclusion: This is the first report to show that uterine fibroids are characterized by an impaired antioxidant cellular enzymatic system. More importantly, our results indicate a role for hypoxia in the modulation of the balance of those enzymes in fibroid and myometrial cells. Collectively, these results shed light on the pathophysiology of fibroids thereby providing potential targets for novel fibroid treatment.