Hematopoietic cell kinase as a nexus for drug repurposing: implications for cancer and HIV therapy

Hematopoietic cell kinase (HCK) has emerged as a potential target for therapeutic intervention in cancer and HIV infection because of its critical role in critical signaling pathways. Repurposing FDA-approved drugs offers an efficient strategy to identify new treatment options. Here, we address the need for novel therapies in cancer and HIV by investigating the potential of repurposed drugs against HCK. Our goal was to identify promising drug candidates with high binding affinities and specific interactions within the HCK binding pocket. We employed an integrated computational approach combining molecular docking and extensive molecular dynamics (MD) simulations. Initially, we analyzed the binding affinities and interaction patterns of a library of FDA-approved drugs sourced from DrugBank. After careful analysis, we focused on two compounds, Nilotinib and Radotinib, which exhibit exceptional binding affinities and specificity to the HCK binding pocket, including the active site. Additionally, we assessed the pharmacological properties of Nilotinib and Radotinib, making them attractive candidates for further drug development. Extensive all-atom MD simulations spanning 200 nanoseconds (ns) elucidated the conformational dynamics and stability of the HCK-Nilotinib and HCK-Radotinib complexes. These simulations demonstrate the robustness of these complexes over extended timescales. Our findings highlighted the potential of Nilotinib and Radotinib as promising candidates against HCK that offer valuable insights into their binding mechanisms. This computational approach provides a comprehensive understanding of drug interactions with HCK and sets the stage for future experimental validation and drug development endeavors.Communicated by Ramaswamy H. Sarma.

Radotinib attenuates TGFβ -mediated pulmonary fibrosis in vitro and in vivo: exploring the potential of drug repurposing

BACKGROUND

Tyrosine kinase (TK) plays a crucial role in the pathogenesis of idiopathic pulmonary fibrosis. Here, we aimed to investigate whether radotinib (Rb) could inhibit pulmonary fibrosis by inhibiting TK in vitro and in vivo.

METHODS

The antifibrotic effects of Rb in transforming growth factor-β (TGF-β)1-stimulated A549 cells were determined using real-time polymerase chain reaction, western blotting, and immunocytochemistry assays. Rb inhibition of bleomycin-induced lung fibrosis in Sprague Dawley (SD) rats was determined by histopathological and​ immunohistochemical analyses. Rb-interfering metabolites were analyzed using LC-MS/MS.

RESULTS

Rb concentrations of up to 1000 nM did not affect the viability of A549 cells, but Rb (30 nM) significantly reduced expression of TGF-β1 (10 ng/mL)-induced ECM factors, such as Snail, Twist, and F-actin. Rb also regulated TGF-β1-overexpressed signal cascades, such as fibronectin and α-smooth muscle actin. Furthermore, Rb attenuated the phosphorylation of Smad2 and phosphorylation of kinases, such as, extracellular signal-regulated kinase, and protein kinase B. In the inhibitory test against bleomycin (5 mg/kg)-induced lung fibrosis, the Rb (30 mg/kg/daily)-treated group showed a half-pulmonary fibrosis region compared to the positive control group. In addition, Rb significantly reduced collagen type I and fibronectin expression in the bleomycin-induced fibrotic region of SD rats. Further, the identified metabolite pantothenic acid was not altered by Rb.

CONCLUSION

Taken together, these results indicate that Rb inhibits TGF-β1-induced pulmonary fibrosis both in vitro and in vivo. These findings suggest that Rb may be an effective treatment for pulmonary fibrosis-related disorders and idiopathic pulmonary fibrosis.

Radotinib enhances cytarabine (Ara-C)-induced acute myeloid leukemia cell death

Background

Acute myeloid leukemia (AML) is a heterogeneous disease that frequently relapses after standard chemotherapy. Therefore, there is a need for the development of novel chemotherapeutic agents that could treat AML effectively. Radotinib, an oral BCR-ABL tyrosine kinase inhibitor, was developed as a drug for the treatment of chronic myeloid leukemia. Previously, we reported that radotinib exerts increased cytotoxic effects towards AML cells. However, little is known about the effects of combining radotinib with Ara-C, a conventional chemotherapeutic agent for AML, with respect to cell death in AML cells. Therefore, we investigated combination effects of radotinib and Ara-C on AML in this study.

Methods

Synergistic anti-cancer effects of radotinib and Ara-C in AML cells including HL60, HEL92.1.7, THP-1 and bone marrow cells from AML patients have been examined. Diverse cell biological assays such as cell viability assay, Annexin V-positive cells, caspase-3 activity, cell cycle distribution, and related signaling pathway have been performed.

Results

The combination of radotinib and Ara-C was found to induce AML cell apoptosis, which involved the mitochondrial pathway. In brief, combined radotinib and Ara-C significantly induced Annexin V-positive cells, cytosolic cytochrome C, and the pro-apoptotic protein Bax in AML cells including HL60, HEL92.1.7, and THP-1. In addition, mitochondrial membrane potential and Bcl-xl protein were markedly decreased by radotinib and Ara-C. Moreover, this combination induced caspase-3 activity. Cleaved caspase-3, 7, and 9 levels were also increased by combined radotinib and Ara-C. Additionally, radotinib and Ara-C co-treatment induced G₀/G₁ arrest via the induction of CDKIs such as p21 and p27 and the inhibition of CDK2 and cyclin E. Thus, radotinib/Ara-C induces mitochondrial-dependent apoptosis and G₀/G₁ arrest via the regulation of the CDKI–CDK–cyclin cascade in AML cells. In addition, our results showed that combined treatment with radotinib and Ara-C inhibits AML cell growth, including tumor volumes and weights in vivo. Also, the combination of radotinib and Ara-C can sensitize cells to chemotherapeutic agents such as daunorubicin or idarubicin in AML cells.

Conclusions

Therefore, our results can be concluded that radotinib in combination with Ara-C possesses a strong anti-AML activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07701-8.

Radotinib induces high cytotoxicity in c-KIT positive acute myeloid leukemia cells

Previously, we reported that radotinib, a BCR-ABL1 tyrosine kinase inhibitor, induced cytotoxicity in acute myeloid leukemia (AML) cells. However, the effects of radotinib in the subpopulation of c-KIT-positive AML cells were unclear. We observed that low-concentration radotinib had more potent cytotoxicity in c-KIT-positive cells than c-KIT-negative cells from AML patients. To address this issue, cell lines with high c-KIT expression, HEL92.1.7, and moderate c-KIT expression, H209, were selected. HEL92.1.7 cells were grouped into intermediate and high c-KIT expression populations. The cytotoxicity of radotinib against the HEL92.1.7 cell population with intermediate c-KIT expression was not different from that of the population with high c-KIT expression. When H209 cells were grouped into c-KIT expression-negative and c-KIT expression-positive populations, radotinib induced cytotoxicity in the c-KIT-positive population, but not the c-KIT-negative population. Thus, radotinib induces cytotoxicity in c-KIT-positive cells, regardless of the c-KIT expression intensity. Therefore, radotinib induces significant cytotoxicity in c-KIT-positive AML cells, suggesting that radotinib is a potential target agent for the treatment of c-KIT-positive malignancies including AML.

Radotinib inhibits acute myeloid leukemia cell proliferation via induction of mitochondrial-dependent apoptosis and CDK inhibitors

Radotinib is a BCR-ABL1 tyrosine kinase inhibitor approved for the second-line treatment of chronic myeloid leukemia. However, effects of radotinib on acute myeloid leukemia (AML) are unclear. In the present study, we observed that radotinib exerted cytotoxic effects on AML cells. Of the various AML cell lines examined (NB4, HL60, HEL 92.1.7, and THP-1), Kasumi-1 was the most sensitive to radotinib. Results of microarray analysis showed that 417 and 595 genes associated with apoptosis and cell cycle regulation, respectively, were differently expressed (i.e., showed >2-fold difference in expression). Radotinib-induced apoptosis involved the mitochondrial pathway. Moreover, radotinib increased the apoptosis of and induced caspase-3 activity in both Kasumi-1 cells and bone marrow cells (BMCs) obtained from patients with AML. Radotinib also increased cleaved caspase-3, caspase-7, and caspase-9 levels and decreased the number of proliferating Kasumi-1 cells and BMCs from patients with AML. In addition, radotinib induced G0/G1 phase arrest by inducing CDKIs p21 and p27 and by inhibiting CDK2, CDK4, and CDK6. These results indicate that radotinib induces caspase-dependent apoptosis and G0/G1 phase arrest in AML cells by regulating CDKI-CDK-cyclin cascade. Moreover, these results indicate that radotinib inhibits AML cell proliferation by inducing mitochondria-dependent apoptosis and CDKIs p21 and p27. To our knowledge, this is the first study to show that radotinib can be potentially used for the anti-leukemic therapy of patients with AML.