Icaritin suppresses multiple myeloma, by inhibiting IL-6/JAK2/STAT3 Icaritin suppresses multiple myeloma, by inhibiting IL-6/JAK2/STAT3

To explore the effects of Icaritin on chronic myeloid leukemia (CML) cells and underlying mechanisms. CML cells were incubated with various concentration of Icaritin for 48 hours, the cell proliferation was analyzed by MTT and the apoptosis was assessed with Annexin V and Hoechst 33258 staining. Cell hemoglobinization was determined. Western blotting was used to evaluate the expressions of MAPK/ERK/JNK signal pathway and Jak-2/Phorpho-Stat3/Phorsph-Akt network-related protein. NOD-SCID nude mice were applied to demonstrate the anti-leukemia effect of Icaritin in vivo. Icaritin potently inhibited proliferation of K562 cells (IC50 was 8 µM) and primary CML cells (IC50 was 13.4 µM for CML-CP and 18 µM for CML-BC), induced CML cells apoptosis and promoted the erythroid differentiation of K562 cells with time-dependent manner. Furthermore, Icaritin was able to suppress the growth of primary CD34+ leukemia cells (CML) and Imatinib-resistant cells, and to induce apoptosis. In mouse leukemia model, Icaritin could prolong lifespan of NOD-SCID nude mice inoculated with K562 cells as effective as Imatinib without suppression of bone marrow. Icaritin could up-regulate phospho-JNK or phospho-C-Jun and down-regulate phospho-ERK, phospho-P-38, Jak-2, phospho-Stat3 and phospho-Akt expression with dose- or time-dependent manner. Icaritin had no influence both on c-Abl and phospho-c-Abl protein expression and mRNA levels of Bcr/Abl. Icaritin from Chinese herb medicine may be a potential anti-CML agent with low adverse effect. The mechanism of anti-leukemia for Icaritin is involved in the regulation of Bcr/Abl downstream signaling. Icaritin may be useful for an alternative therapeutic choice of Imatinib-resistant forms of CML.

The clinical significance and mechanisms of TET2 are not well defined in myeloid malignancies. We detected TET2 mutations and assayed its catalyzing conversion product 5-hydroxymethylcytosine (5-hmC) in 61 Chinese patients with MDS. Ten patients were identified to have TET2 mutations (16.4%). 5-hmC levels in patients with MDS with TET2 mutations were significantly lower than in those without mutations, and CD34+ cells of patients with MDS exhibited a lower 5-hmC content than that of controls. TET2 expression and 5-hmC in patients with MDS with P15 methylation were both significantly lower than in those without P15 methylation. We did not observe a correlation between TET2 mutations and overall survival (OS) in MDS. Interestingly, we found that patients with MDS with higher 5-hmC levels or in lower risk groups of the Revised International Prognostic Scoring System (IPSS-R) had a longer overall survival, suggesting that 5-hmC levels may be a new molecular marker for prognostic assessment of MDS and that revised IPSS criteria are also applicable to the risk categories of Chinese patients with MDS.

Background: To identify novel proteins involved in multidrug resistance in chronic myeloid leukemia (CML). Materials and methods: Comparative proteomics was used to screen multidrug resistance-related proteins from K562 and K562/A02; the differently expressed proteins were further confirmed by western blot and real-time PCR. short hairpin RNA (shRNA) assay was applied to determine the relationship between candidate protein and adriamycin resistance. Bisulfite sequencing was carried out to assess methylation status of candidate multidrug resistance-related gene promoter. K562/A02 was treated with 5-azacytidine or trichostatin A (TSA); multidrug resistance phenotype and corresponding protein or gene changes were detected. Results: Seventeen proteins with altered abundances of more than twofold were detected, among which mitochondrial ATPase in K562/A02 was significantly down-regulated. Suppressing mitochondrial ATPase by shRNA could enhance adriamycin resistance and antiapoptosis activity of K562. The promoter hypermethylation in mitochondrial ATPase was found to be attributed to the adriamycin-resistant phenotype of both K562/A02 (methylated frequency 18.18%) and CML primary cells in accelerated phase (methylated frequency 7.95%) or blast crisis (methylated frequency 26.59%). Inhibition of hypermethylation increased adriamycin sensitivity of K562/A02. A synergistic effect on reversing adriamycin-resistant phenotype was obtained when 5-azacytidine was combined with TSA. Conclusion: Down-regulation of mitochondrial ATPase can lead to adriamycin resistance in CML and the mechanism is associated with DNA methylation regulation.