Session: MON 414-436-HPT Axis Biology & Action
Poster Board MON-423
Objective: Effect of triiodothyronine (T3) excess on erythroid differentiation of K562 human erythroleukemia cells was investigated to explore the mechanism of anemia in hyperthyroidism.
Methods: K562 cells were cultured in RPMI 1640 medium with 10% fetal bovine serum (FBS). Expression of thyroid hormone receptors (TRs; TR alpha, TR beta, and RXR) was confirmed by PCR. K562 cells were preincubated in the presence (treatment group) or absence (control group) of 10-100nM T3 for 4 days. Then, the cells in both group were exposed to 50μM hemin for 72 hours to induce erythroid differentiation. Hemin-induced erythroid differentiation was analyzed by benzidine staining and measuring hemoglobin content. Additionally, cell surface markers (CD71) were analyzed by flow cytometry.
Results: Steady expression of TRs was detected in K562 cells. Benzidine-positive rate before hemin exposure was approximately 7%. When 50μM hemin was added to the culture medium, K562 cells showed signs of differentiation and synthesized hemoglobin. In the control group, benzidine-positive rate increased approximately 70%. In the treatment group, T3 treatment inhibited the erythroid differentiation in a concentration-dependent manner, where maximum inhibitory effect of T3 occurred at the concentration of 100nM. Benzidine-positive rate in the treatment group decreased approximately 60%. T3 treatment also decreased hemoglobin content of hemin-induced K562 cells. Flow cytometry analysis revealed that the number of CD71 positive cells with mature differentiation was markedly lower in the treatment group.
Discussion: T3 is an essential hormone for erythropoiesis similar to erythropoietin. TRs were expressed in K562 human erythroleukemia cells. Excess of T3 induced a significant decrease of benzidine-positive rate and hemoglobin content after hemin-induced erythroid differentiation. In addition, T3 preincubation reduced CD71 positive cells with mature differentiation, suggesting the important role of T3 excess in erythropoiesis.
Conclusion: T3 excess inhibited hemin-induced erythroid differentiation of K562 cells.
Nothing to Disclose: MS, YY, YO, NH, ST, YT
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