3-Aroyl-1,4-diarylpyrroles inhibit chronic myeloid leukemia cell growth through an interaction with tubulin

We designed 3-aroyl-1,4-diarylpyrrole (ARDAP) derivatives as potential anticancer agents having different substituents at the 1- or 4-phenyl ring. ARDAP compounds exhibited potent inhibition of tubulin polymerization, binding of colchicine to tubulin, and cancer cell growth. ARDAP derivative 10 inhibited the proliferation of BCR/ABL-expressing KU812 and LAMA84 cells from chronic myeloid leukemia (CML) patients in blast crisis and of hematopoietic cells ectopically expressing the imatinib mesylate (IM)-sensitive KBM5-WT or its IM-resistant KBM5-T315I mutation. Compound 10 minimally affected the proliferation of normal blood cells, indicating that it may be a promising agent to overcome broad tyrosine kinase inhibitor resistance in relapsed/refractory CML patients. Compound 10 significantly decreased CML proliferation by inducing G2/M phase arrest and apoptosis via a mitochondria-dependent pathway. ARDAP 10 augmented the cytotoxic effects of IM in human CML cells. Compound 10 represents a robust lead compound to develop tubulin inhibitors with potential as novel treatments for CML

3-Aroyl-1,4-diarylpyrroles inhibit chronic myeloid leukemia cell growth through an interaction with tubulin

Microtubules are an attractive target for the development of effective anti-leukemia agents.[1] Evidence has accumulated correlating inhibition of tubulin polymerization and leukemic cell proliferation.[2] The activity of colchicine site agents in chronic myeloid leukemia (CML) has not been adequately explored. Recently, starting from previously reported aroylindoles (ARI, 1)[3] we developed a class of 3-aroyl-1-arylpyrroles (ARAPs, 2) via benzocracking approach by shifting the indole benzene moiety to position 1 of the pyrrole ring.[4] ARAPs proved to be potent inhibitors of both tubulin assembly and cancer cells growth, by binding the colchicine binding site. Pursuing our studied on tubulin targeting agents, we designed 3-aroyl-1,4-diarylpyrroles (ARDAPs, 3-16) as potential anticancer agents bearing different substituents at the 1- or 4-phenyl ring (Chart 1). ARDAPs exhibited potent inhibition of tubulin polymerization, binding of colchicine to tubulin and cancer cell growth. (4-(4-Aminophenyl)-1-phenyl-1H-pyrrol-3-yl)(3,4,5-trimethoxyphenyl)methanone inhibited the proliferation of BCR/ABL-expressing KU812 and LAMA84 cells from CML patients in blast crisis and of hematopoietic cells ectopically expressing the imatinib mesylate (IM)-sensitive KBM5-WT or its IM-resistant KBM5-T315I mutation. The same compound minimally affected the proliferation of normal blood cells, indicating that it may be a promising agent to overcome broad tyrosine kinase inhibitor resistance in relapsed/refractory CML patients. New ARDAP significantly decreased CML proliferation by inducing G2/M phase arrest and apoptosis via a mitochondria-dependent pathway and increased the cytotoxic effects of IM in human CML cells. References. [1] de Bruin, E. C.; Medema, J. P. Cancer Treat. Rev. 2008, 34, 737-749. [2] Bates, D.; Feris, E. J.; Danilov, A. V. et al. Cancer Biol. Ther. 2016, 17, 291-299. [3] La Regina, G.; Sarkar, T.; Bai, R. et al. J. Med. Chem. 2009, 52, 7512-7527. [4] La Regina, G.; Bai, R.; Coluccia, A. et al. J. Med. Chem. 2014, 57, 6531-6552

Treating chronic myeloid leukemia by inhibition of tubulin polymerization

Microtubules are an attractive target for the development of active anti-leukemia agents (1). Despite some evidence, the therapeutic potential of colchicine site binding agents in chronic myeloid leukemia (CML) has not been adequately explored. Recently, starting from previously reported aroylindoles (ARIs, e.g. 1) we have developed 3-aroyl-1-arylpyrroles (ARAPs, e.g. 2) via benzocracking approach (Chart 1) (2). Pursuing our studies, we designed and synthesized 3-aroyl-1,4-diarylpyrroles (ARDAPs, 3-16) as potential anticancer agents (3). ARDAPs exhibited potent inhibition of tubulin polymerization, binding of colchicine to tubulin and cancer cell growth. (4-(4-Aminophenyl)-1-phenyl-1H-pyrrol-3-yl)(3,4,5-trimethoxyphenyl)methanone inhibited the proliferation of BCR/ABL-expressing KU812 and LAMA84 cells from CML patients in blast crisis and of hematopoietic cells ectopically expressing the imatinib mesylate (IM)-sensitive KBM5-WT or its IM-resistant KBM5-T315I mutation. The same compound minimally affected the proliferation of normal blood cells, indicating that it may be a promising agent to overcome broad tyrosine kinase inhibitor resistance in relapsed/refractory CML patients. New ARDAP significantly decreased CML proliferation by inducing G2/M phase arrest and apoptosis via mitochondria-dependent pathway and increased the cytotoxic effects of IM in human CML cells. References. (1) Yeh, Y.-Y.; Liou, J.-P.; Lee, Y.-L. et al. Invest. New Drugs 2017, 35, 427-435. (2) La Regina, G.; Bai, R.; Coluccia, A. et al. J. Med. Chem. 2014, 57, 6531-6552. (3) La Regina, G.; Bai, R.; Coluccia, A. et al. ACS Med. Chem. Lett. 2017, 8, 521-526

In vitro and in vivo activity of SKI-606, a novel Src-Abl inhibitor, against imatinib-resistant Bcr-Abl⁺ neoplastic cells

Resistance to imatinib represents an important scientific and clinical issue in chronic myelogenous leukemia. In the present study, the effects of the novel inhibitor SKI-606 on various models of resistance to imatinib were studied. SKI-606 proved to be an active inhibitor of Bcr-Abl in several chronic myelogenous leukemia cell lines and transfectants, with IC(50) values in the low nanomolar range, 1 to 2 logs lower than those obtained with imatinib. Cells expressing activated forms of KIT or platelet-derived growth factor receptor (PDGFR), two additional targets of imatinib, were unaffected by SKI-606, whereas activity was found against PIM2. SKI-606 retained activity in cells where resistance to imatinib was caused by BCR-ABL gene amplification and in three of four Bcr-Abl point mutants tested. In vivo experiments confirmed SKI-606 activity in models where resistance was not caused by mutations as well as in cells carrying the Y253F, E255K, and D276G mutations. Modeling considerations attribute the superior activity of SKI-606 to its ability to bind a conformation of Bcr-Abl different from imatinib

SKI-606 decreases growth and motility of colorectal cancer cells by preventing pp60(c-Src)-dependent tyrosine phosphorylation of \uce\ub2-catenin and its nuclear signaling

Inhibition of deregulated protein tyrosine kinases represents an attractive strategy for controlling cancer growth. However, target specificity is an essential aim of this strategy. In this report, pp60(c-Src) kinase and \uce\ub2-catenin were found physically associated and constitutively activated on tyrosine residues in human colorectal cancer cells. The use of specific small-interfering RNAs (siRNA) validated pp60(c-Src) as the major kinase responsible for \uce\ub2-catenin tyrosine phosphorylation in colorectal cancer. Src-dependent activation of \uce\ub2-catenin was prevented by SKI-606, a novel Src family kinase inhibitor, which also abrogated \uce\ub2-catenin nuclear function by impairing its binding to the TCF4 transcription factor and its trans-activating ability in colorectal cancer cells. These effects were seemingly specific, as cyclin D1, a crucial \uce\ub2-catenin/TCF4 target gene, was also down-regulated by SKI-606 in a dose-dependent manner accounting, at least in part, for the reduced growth (IC50, 1.5-2.4 \uce\ubcmol/L) and clonogenic potential of colorectal cancer cells. Protein levels of \uce\ub2-catenin remained substantially unchanged by SKI-606, which promoted instead a cytosolic/membranous retention of \uce\ub2-catenin as judged by immunoblotting analysis of cytosolic/nuclear extracts and cell immunofluorescence staining. The SKI-606-mediated relocalization of \uce\ub2-catenin increased its binding affinity to E-cadherin and adhesion of colorectal cancer cells, with ensuing reduced motility in a wound healing assay. Interestingly, the siRNA-driven knockdown of \uce\ub2-catenin removed the effect of SKI-606 on cell-to-cell adhesion, which was associated with prolonged stability of E-cadherin protein in a pulse-chase experiment. Thus, our results show that SKI-606 operates a switch between the transcriptional and adhesive function of \uce\ub2-catenin by inhibiting its pp60(c-Src)-dependent tyrosine phosphorylation; this could constitute a new therapeutic target in colorectal cancer. \uc2\ua92006 American Association for Cancer Research

Validation of PDGFRβ and c-Src tyrosine kinases as tumor/vessel targets in patients with multiple myeloma: Preclinical efficacy of the novel, orally available inhibitor dasatinib

Inhibition of multiple myeloma (MM) plasma cells in their permissive bone marrow microenvironment represents an attractive strategy for blocking the tumor/ vessel growth associated with the disease progression. However, target specificity is an essential aim of this approach. Here, we identified platelet-derived growth factor (PDGF)-receptor beta (PDGFRp) and pp60c-Src as shared constitutively activated tyrosine-kinases (TKs) in plasma cells and endothelial cells (ECs) isolated from MM patients (MMECs). Our cellular and molecular dissection showed that the PDGF-BB/PDGFRp kinase axis promoted MM tumor growth and vessel sprouting by activating ERK1/2, AKT, and the transcription of MMEC-released proangiogenic factors, such as vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8). Interestingly, pp60c-Src TK-activity was selectively induced by VEGF in MM tumor and ECs, and the use of small-interfering (si)RNAs validated pp60c-Src as a key signaling effector of VEGF loop required for MMEC survival, migration, and angiogenesis. We also assessed the antitumor/vessel activity of dasatinib, a novel orally bioactive PDGFRp/Src TK- inhibitor that significantly delayed MM tumor growth and angiogenesis in vivo, showing a synergistic cytotoxicity with conventional and novel antimyeloma drugs (ie, melphalan, prednisone, bor- tezomib, and thalidomide). Overall data highlight the biologic and therapeutic relevance of the combined targeting of PDGFRp/c-Src TKs in MM, providing a framework for future clinical trials. © 2008 by The American Society of Hematology