In vivo gene expression profling in the murine 5T33MM model identifies epigenetic-regulated genes predictive for prognosis and drug sensitivity

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Epigenetic modulating agents, including DNA methyltransferase inhibitors (DNMTi) and histone deacetylase inhibitors (HDACi), are of interest for their anti-tumor properties. Decitabine (DAC) is a FDA approved DNMTi for treatment of myelodysplastic syndrome, while JNJ-26481585 (JNJ-585) is a HDACi with potent anti-myeloma activity. Several studies revealed that DNMTi and HDACi exert their anti-tumor response by reversing epigenetic changes resulting in alterations in the transcriptome. In addition, DNMTi and HDACi exert direct cytotoxic effects. Limited studies are available on DAC alone and in combination with HDACi in multiple myeloma. Therefore we assessed the potential synergistic effect of DAC and JNJ-585 in MM.

For in vitro experiments, we focused on human (OPM-2, RPMI 8226) and murine (5T33MM) cell lines. Using Cell-Titer-Glo, DAC and JNJ-585 showed synergistic anti-myeloma effects. This was confirmed by an AnnexinV-7AAD apoptosis assay. In general, apoptosis was associated with H2AX phosphorylation, caspase- and PARP-cleavage, which was more pronounced in the combination. In the OPM-2 cells, we also observed Mcl-1 cleavage and Bim upregulation. DAC and JNJ-585 also affected cell cycle progression. In the 5T33MMvt cells, DAC induced a G2/M-phase arrest while JNJ-585 induced a G0/G1-phase arrest. Combining both agents cancelled out the observed arrests and resulted in subG1 increase. In OPM-2 cells, DAC did not induce an arrest while JNJ-585 induced a G0/G1-phase arrest, which was maintained in the combination. In support of the cell cycle arrest, p21 and p27 were upregulated in both cell lines. Lastly, in the 5T33MM murine model, combination treatment resulted in significant lower serum M-spike, bone marrow tumor load and increased survival probability compared to single agent treatment.

In conclusion, we demonstrated a synergistic anti-myeloma effect of DAC and JNJ-585. This was associated with a DNA damage response, cell cycle arrest, caspase activation and disruption of Bcl-2 family balance. DAC and JNJ-585 treatment in vivo resulted in slower disease progression suggesting clinical relevance.
Original languageEnglish
JournalBelgian Journal of Hematology
Publication statusPublished - 30 Jan 2014
Event30th General Annual Meeting of Belgian Hematological Society - La Hulpe, Belgium
Duration: 30 Jan 2015 → …


  • Microarray
  • Multiple Myeloma
  • epigenetics


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