FIGURE 2.
HK2 is upregulated through HIF activation in hypoxia‐stressed myeloma cells. A, Volcano plot showing the distribution of differentially expressed genes between primary MM samples (n = 4) cultured in hypoxia (1% O2) vs normoxia for 48 h (GSE80545). Red dots illustrate transcripts significantly upregulated by hypoxia (fold change >2.0, P < .05). B, Gene Ontology (GO) analysis of hypoxia‐induced genes (red dots in A). C, Heat map of 15 probes (13 genes) including GO “glycolytic process” of (B). D, Scheme of the glycolytic process. Red arrows: genes upregulated by hypoxia displayed in (C). E, Gene expression change of HK1, HK2, HK3, and HK4 in patient samples cultured in hypoxia (1% O2) vs normoxia for 48 h (GSE80545). F, qRT‐PCR of HK2 for cell lines (U266, KMS‐11, and MM.1S) cultured under hypoxia (1% O2), serum starvation, with recombinant IL‐6 (4 ng/mL), co‐cultured with a stromal cell line HS‐5 (only U266) for 24 h. G, qRT‐PCR of HK2 for cell lines (U266, KMS‐11, and MM.1S) transiently transduced with siHIF1A and/or siHIF2A and control scrambled siRNA and cultured in normoxia or hypoxia (1% O2) for 48 h. H, Western blot analysis of HK2 for primary samples (n = 2) and cell lines (KMS‐11, MM.1S, U266, RPMI‐8226, KMS‐12‐PE, and H929) cultured in normoxia or hypoxia (1% O2) for 48 h. H, hypoxia; N, normoxia. Asterisks indicate statistical significance: *.01 ≤ P < .05; **.001 ≤ P < .01; ***P < .001; NS, not significant