We present a patient who developed severe anemia and neutropenia after receiving parenteral nutrition for 2.5 years. The serum levels of copper and ceruloplasmin were low, and the bone marrow showed the presence of ringed sideroblasts and vacuolated immature cells. The administration of copper chloride by bolus injection led to a rapid improvement in anemia and neutropenia. The number of progenitor cells (colony-forming unit-granulocyte-macrophage and erythrocyte) present before the copper supplementation was well preserved. It is therefore suggested that copper enzymes play an important role in the maturation of hematopoietic cells.

Thiazolidinedione (TZD) is known to be a potent activator of peroxisome proliferator-activated receptor γ (PPARγ), a nuclear receptor that constitutes a heterodimer with retinoid X receptor (RXR). Since a considerable amount of PPARγ is expressed in various hematopoietic cells, the present study was undertaken to examine the effect of TZD in the absence or presence of LG100268, an RXR-selective ligand, on a cultured promyelocytic leukemia cell line, HL60. Treatment with TZD (25–50 µM troglitazone or pioglitazone) markedly suppressed cell proliferation of HL60. A cell cycle analysis revealed that the suppressive effect of troglitazone on HL60 cell proliferations was caused by G0/G1 cell cycle arrest as well as by an apoptotic effect. Treatment with the same concentration of troglitazone also induced the monocytic differentiation of HL60 cells. The apoptotic or the differentiating effect of TZD on HL60 cells was synergistically enhanced by the combined treatment with 1 µM LG100268, while LG100268 alone neither had an apoptotic nor a differentiating effect on HL60 cells. These results suggest that these actions are mediated through the nuclear receptor system constituted by the PPARγ: RXR heterodimer.

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