SDHB deficiency induces pseudohypoxia and reprograms iron homeostasis. A,
SDHB knockdown efficiency in mouse pheochromocytoma (MPC) and hPheo1 cell lines was measured by Western blot analysis (top) and quantification (bottom, n = 3). β-actin was used as a loading control. B,
SDHB knockdown efficiency in MPC and hPheo1 cell lines was measured by qRT-PCR (n = 4). C, HIF-1α, HIF-2α, TF, TFR2, and DMT1 proteins in SDHBWT and SDHBKD MPC cells were measured by Western blot analysis (left) and quantification (right, n = 3). β-actin was used as a loading control. D, Levels of TF, TFR2, SLC11A2 (DMT1), EPO, PGK1, and LDHA mRNA were measured by qRT-PCR. Data normalized to SDHBWT. E, Levels of HIF1A, HIF2A, TF, TFR2, SLC11A2, EPO, TFRC, and LDHA mRNA in cluster I and cluster II PCPG frozen tissues were measured by qRT-PCR. CI, cluster I (n = 5–8); CII, cluster II (n = 4–7). F, Expression of DMT1, TF, and TFR2 in cluster I (n = 4) and cluster II (n = 5) PCPGs was measured by IHC staining obtained from cluster I and cluster II PCPG FFPE tissues. Scale bar, 50 μm. CI, cluster I; CII, cluster II; NAM, normal adrenal medulla. G, Integrated optical density quantification of the IHC staining shown in (F). Cluster I (CI), n = 4; cluster II (CII), n = 5. H, Promoter affinity of HIF-1α assay in SDHBWT and SDHBKD hPheo1 cells was measured by a ChIP PCR assay. I, The level of the labile iron pools in SDHBWT and SDHBKD mouse pheochromocytoma cells was measured by a cellular labile iron pool quantification assay. J, Knockdown efficiency of siRNA targeting TF in mouse pheochromocytoma cells was measured by Western blot analysis (top) and qRT-PCR (bottom). K, The level of the labile iron pools in SDHBWT and SDHBKD mouse pheochromocytoma cells after TF knockdown was measured by a cellular labile iron pool quantification assay. L, The level of the labile iron pools in SDHBKD mouse pheochromocytoma cells after HIF1A and HIF2A knockdown was measured by a cellular labile iron pool quantification assay. All significance in differences were determined by t test [*, P < 0.05; **, P < 0.01; ***, P < 0.001 (±SEM)].