Heme oxygenases are enzymes that catalyze the degradation of heme into biliverdin, free iron, and carbon monoxide. There are two main isoforms: HO-1, which is highly inducible under stress conditions, and HO-2, which is constitutively expressed.
HO-2 is constitutively expressed in many tissues and is less sensitive to stress-induced upregulation compared to HO-1.
It contributes to normal cellular heme turnover, with the resulting products (e.g., biliverdin, bilirubin, and carbon monoxide) having cytoprotective, anti-inflammatory, and anti-apoptotic properties.
-Higher constitutive expression of HO-2 has been associated with maintaining cell survival under conditions of oxidative stress, which, in turn, could be linked to more aggressive tumor behavior or resistance to therapy in certain contexts.
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