After haemin treatment intracellular non-haem iron increases prior to haem oxygenase-1 induction: A study in human monocytic cell line THP-1

• Published in: Transfusion and apheresis science 2019-12, Vol.58 (6), p.102662-102662, Article 102662
• Main Authors: Imoto, Shion, Shibuya, Yukiko, Kono, Mari, Ohbuchi, Ayako, Sawamura, Tohru, Suzuki, Takashi, Mizokoshi, Yuji, Sawada, Hirohide, Saigo, Katsuyasu
• Format: Article
• Language: English
• Subjects: Cell Death - drug effects; Enzyme Induction - drug effects; Ferroptosis; Health technology assessment; Heme oxygenase; Heme Oxygenase (Decyclizing) - metabolism; Heme Oxygenase-1 - biosynthesis; Hemin; Hemin - pharmacology; Humans; Intracellular Space - metabolism; Iron - metabolism; Macrophages; Monocytes - drug effects; Monocytes - enzymology; Reactive Oxygen Species - metabolism; THP-1 Cells; Time Factors; Transfusion iron overload
• ISSN: 1473-0502; 1878-1683
• DOI: 10.1016/j.transci.2019.10.004

Iron overload is a major health concern for transfusion-dependent patients. Repeated transfusions result in the loading of large amounts of haem-derived iron on macrophages, in turn, inducing cell death. We previously demonstrated that haemin-induced cell death in human monocytic THP-1 cells is consistent with ferroptosis, an iron-dependent cell death regulation mechanism. However, direct measurement of iron after haemin treatment has not yet been conducted. In this study, we measured intracellular non-haem iron concentration and haem oxygenase levels after haemin treatment. Human monocytic THP-1 cells were treated with haemin, and the cell lysate was prepared. Non-haem iron concentration of the cell lysate was measured using the Nitroso-PSAP method. Expression of haem oxygenase-1 (HO-1) and haem oxygenase-2 (HO-2) was quantified by western blotting. We measured intracellular non-haem iron and the expression of haem oxygenases post-haemin treatment. Concentration of non-haem iron post-haemin treatment increased dependently with time and dose. HO-1 expression was detected 4 h after haemin treatment, whereas HO-2 expression was constitutive. Increase in non-haem iron prior to induction of HO-1 expression suggests the involvement of HO-2 in haem-induced cytotoxicity. (184 words)