HMOX1 and cancer: However, although preclinical studies on HO-1 and its inducers in the treatment of acute and chronic kidney diseases are abundant and have shown beneficial effects, their side effects are also evident (80): First, in recent years, more and more evidence supports that the excessive upregulation of HO-1 is related to the poor prognosis of certain malignant tumors (81), especially breast cancer, renal cell carcinoma, and liver cancer.