In-vitro and In-silico Analyses of Anti-leukaemic Activity of Novel Organometallic Compound Strontium-Phenanthroline in BCR-ABL1 Positive CML Cells and DEK-CAN Positive High-Risk AML Cells

Abstract

Existing armamentarium of chemotherapies coupled with targeted therapies for leukaemia has failed to establish as adequate treatment option. Leukaemic stem cells along with adaptive resistance and refractory disease are the salient factors behind plasticity as a therapy response in leukaemia. There is lack of targeted therapy for prognostically poor DEK-CAN positive, with translocation t(6;9)(p23;q34), high-risk acute myeloid leukaemia (AML). While, in BCR-ABL1 positive chronic myeloid leukaemia (CML), acquired and intrinsic mutations cause resistance to tyrosine kinase inhibitors (TKIs) like imatinib. Range of organometallic compounds and complexes have already exhibited potent anticancer activity in solid cancer. Strontium-Phenanthroline (Sr-Phen), a novel organometallic compound, was evaluated in this three-phased study with the aim to explore its anti-leukaemic potential and its possible mechanisms of action. In order to shortlist potential cellular protein targets for Sr-Phen, investigative molecular docking and protein-ligand interaction profiling was performed in K562 (BCR-ABL1 positive CML) and FKH-1 (DEK-CAN AML positive) cell lines. This was followed by in-vitro cytotoxicity profiling of Sr-Phen in K562 and FKH-1 cells using MTT assay. Subsequently, expression analysis was performed through qRT-PCR to determine the effect of pharmacological targeting by Sr-Phen on AXL and Wnt/β-Catenin target genes like c-Myc and Axin2. The in-silico results showed high affinity of Sr-Phen with least free binding energy to Dbl homology domain of BCR (-9.67kcal/mol) and DEK (-8.22kcal/mol) in K562 and FKH-1 cell lines, respectively. Sr-Phen strongly interfered with proliferation of both DEK-CAN positive FKH-1 cells; approximately 80% proliferation reduction at 1.25μm concentration with p<0.0001 and BCR-ABL1 positive K562 cells; 50% proliferation reduction at 1.25μm concentration with p<0.05. Additionally, Sr-Phen also downregulated AXL (≈ 0.3-fold change) and Wnt/β-Catenin target genes c-Myc (≈ 0.3-fold change) and Axin2 (≈ 0.3-fold change).Imatinib also downregulated AXL (≈ 0.5-fold change), c-Myc (≈ 0.3-fold change), and Axin2 (≈ 0.5-fold change) in K562 cells. The in-silico results together with in-vitro results of Sr-Phen suggested similar and efficient binding of Sr-Phen with BCR region of BCR-ABL1 as compared to imatinib prompting the anti-leukaemic potential of Sr-Phen in BCR-ABL1 positive CML cells. Furthermore, Sr-Phen seems to interfere with BCR-ABL1 downstream signalling in a similar manner to imatinib. Hence, this study proffers Sr-Phen organometallic as a new possible treatment option for BCR-ABL1 positive CML.