The effect of hedgehog inhibition and autophagy modulation on the proliferation and survival of AML cell lines /

Abstract

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy which occurs as a result of many chromosomal abnormalities such as translocations, deletions or insertions. Aberrant signaling pathways such as PI3K/AKT/mTOR, Notch and Hedgehog pathway have a role in the pathogenesis of AML. Hedgehog pathway (Hh) is a conserved signalling pathway that is important during embryogenesis. It crosstalks with other pathways and regulate autophagy, a cellular degradation and organelle turnover process. Several studies suggested that autophagy modulation could act as an escape mechanism in AML. Given the role of autophagy and Hh in AML, understanding the relationship between autophagy and Hh pathway is important to overcome the leukemic growth. Hence, we checked the effect of Hh inhibition using GANT61 on MOLM-13 and CMK cells using MTT cell viability assay. GANT61 led to a decrease in the both MOLM-13 and CMK cells. After that, we sought to understand the effect of autophagy modulation on CMK and MOLM-13 cell lines and we have found that autophagy inhibitors, NH4CI, Chloroquine(CQ), Hydroxychloroquine and Nocodazole lead to a decrease in the proliferation of CMK and MOLM-13 cell lines. However, PP242, an autophagy activator, had no effect on the proliferation of CMK and MOLM-13 cell lines. Combination treatment of autophagy modulators and GANT61 had a synergistic effect on MOLM-13 but not on CMK. GANT61 treatment increased autophagy in AML cell lines that were correlated with an increase in the expression of LC3B-II detected by western blotting. Also, combination treatment with nocodazole and GANT61 elevated that increase in LC3B-II in both MOLM-13 and CMK cell lines. AKT protein expression changed depending on the type of treatment and cell lines. In conclusion, targeting of Hh and autophagy is a promising therapy against MOLM-13 cell line but not against CMK.