Deacetylase inhibitors for the treatment of myelodysplastic syndromes

Effects of signaling pathway inhibitors on hematopoietic stem cells

While there are numerous small molecule inhibitory drugs available for a wide range of signalling pathways, at present, they are generally not used in combination in clinical settings. Previous reports have reported that the effects of glycogen synthase kinase (GSK)3β, p38MAPK, mTOR and histone deacetylase signaling combined together to suppress the stem-like nature of hematopoietic stem cells (HSCs), driving these cells to differentiate, cease proliferating and thereby impairing normal hematopoietic functionality. The present study aimed to determine the effect of HDACs, mTOR, GSK-3β and p38MAPK inhibitor combinations on the efficient expansion of HSCs using flow cytometry. Moreover, it specifically aimed to determine how inhibitors of the GSK3β signaling pathway, in combination with inhibitors of P38MAPK and mTOR signaling or histone deacetylase (HDAC) inhibitors, could affect HSC expansion, with the goal of identifying novel combination strategies useful for the expansion of HSCs. The results indicated that p38MAPK and/or GSK3β inhibitors increased Lin⁻ cell and Lin⁻Sca-1⁺c-kit⁺ (LSK) cell numbers in vitro. Taken together, these results suggested that a combination of p38MAPK and GSK3β signaling may regulate HSC differentiation in vitro. These findings further indicated that the suppression of p38MAPK and/or GSK3β signalling may modulate HSC differentiation and self-renewal to enhance HSC expansion.

Artesunate Induces SKM-1 Cells Apoptosis by Inhibiting Hyperactive β-catenin Signaling Pathway

INTRODUCTION

Artesunate (ART), a wildly used agent to treat severe malarial around the world, also has the power to inhibit growth of different types of tumor. However, the exact molecular mechanisms keep unknown.

METHOD

In this study, we used myelodysplastic syndrome (MDS) cells (SKM-1 cells) with differential ART concentrations treatment at multiple time points to observe the subsequence cell function alteration and the possible involved pathway genes.

RESULTS

We found that ART demonstrated the ability to inhibit proliferation and induce apoptosis in SKM-1 in a dose and time-dependent manner. Demethylase recovered CDH1 gene expression may be involved in the apoptosis process. The β-catenin protein translocated from the nucleus and cytoplasm to the membrane result in inactivation of β-catenin signaling pathway.

CONCLUSION

Our findings provide a rational basis to develop ART as a useful therapeutic agent for the treatment of myelodysplastic syndromes.