Abstract 91: Molecular insight into drug resistance in acute myeloid leukemia: An in-silico and in-vitro approach

Abstract

Abstract INTRODUCTION: Drug resistance of leukemic stem cells is a surmountable obstacle to effective chemotherapy in acute myeloid leukemia (AML). P-glycoprotein (Pgp) and FLT3 undoubtedly contribute to worse prognosis and mechanisms of these proteins lead to shorter survival and chemotherapy resistance. Due to heterogeneity of stem cells in AML, outcome of patients with a normal karyotype is highly challenging and changes in drug resistance genes likely to be identified which will contribute to a better understanding of the disease biology, eventually leading to the development of alternative therapeutic approaches regarding drug resistance in AML. METHODOLOGY: Blood and Bone-marrow samples were collected from newly diagnosed adult AML patients with normal karyotype. Gene expression analysis of MDR genes like Pgp, MRP1, BCRP and LRP was done by qRT-PCR in FLT3-ITD+/- and CD34+/- subgroups. Higher expression of Pgp amongst all MDR genes instigated to undertake in-silico analysis of Pgp with natural compound library using YASARA. MTT assay was used to find out IC50 value of natural compounds shortlisted from in-silico analysis and used alone or with cytarabine on THP-1 cell line and in primary AML stem cells. Pgp inhibitory activity of natural compounds was assessed by fluorimetric MDR assay. RESULTS: A significant upregulation of Pgp expression was observed in FLT3-ITD+, CD34+ group after cytarabine exposure during their induction (7+3) therapy. Docking analysis revealed curcumin, hesperidin and silymarin having better binding affinity with Pgp as compared to its known inhibitor Verapamil. Furthermore, these selected compounds were used in-vitro, and results of MTT assay suggested 6.1µM, 40.73µM, 63.09µM and 54.95µM IC50 values of cytarabine, curcumin, hesperidin and silymarin respectively in THP-1 cell line. Combination index (CI) analysis revealed that curcumin (25µM), hesperidin (30µM) and silymarin (35µM) having synergistic effect with cytarabine and decreased IC50 value of cytarabine (1µM). In addition to this, Silymarin at 250nM and 500nM concentration showed equivalent inhibition of Pgp as compared to control Verapamil. CONCLUSION: A combination of in-silico and in-vitro screening revealed Curcumin, Hesperidin and Silibinin can be used as MDR modulators as well as chemosensitizer to reduce the cytotoxicity profile and drug resistance in AML. Citation Format: Urja Desai, Sheefa Mirza, Sonia Parikh, Rakesh Rawal. Molecular insight into drug resistance in acute myeloid leukemia: An in-silico and in-vitro approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 91. doi:10.1158/1538-7445.AM2017-91