Design and synthesis of novel thiazole-derivatives as potent ALK5 inhibitors.

TGF-ß is an immunosuppressive cytokine and plays a key role in progression of cancer by inducing immunosuppression in tumor microenvironment. Therefore, inhibition of TGF-ß signaling pathway may provide a potential therapeutic intervention in treating cancers. Herein, we report the discovery of a series of novel thiazole derivatives as potent inhibitors of ALK5, a serine-threonine kinase which is responsible for TGF-ß signal transduction. Compound 29b was identified as a potent inhibitor of ALK5 with an IC50 value of 3.7 nM with an excellent kinase selectivity.

A novel anticancer quinolone, (R)-WAC-224, has anti-leukemia activities against acute myeloid leukemia.

Approximately 60%-80% of patients who achieve complete remission eventually relapse after conventional chemotherapy and have poor prognoses despite the recent advances of novel anticancer agents. Continuing development of more effective novel treatments for acute myeloid leukemia (AML) is necessary. We developed (R)-WAC-224 (R-WAC), which is an anticancer quinolone, targeting topoisomerase II. This study evaluated the anti-leukemia potential of R-WAC or racemic WAC-224 (WAC) in vitro and in vivo. R-WAC significantly inhibited the human AML cell line proliferation (MV4-11, HL60, and KG1a), which was comparable to daunorubicin and cytarabine, not affected by P-glycoprotein overexpression. WAC did neither increase serum troponin-T nor decrease the crypt numbers in the small intestine, indicating WAC was less toxic than doxorubicin. R-WAC monotherapy demonstrated prolonged survival in the AML mice model and inhibited tumor growth in the MV4-11 xenograft mice model. Moreover, the combination of R-WAC and cytarabine demonstrated more active anti-leukemia effects than daunorubicin and cytarabine. Finally, R-WAC inhibited the colony-forming abilities using primary AML cells. These results indicate that R-WAC is a promising therapeutic agent for AML.

Creation of Philadelphia chromosome by CRISPR/Cas9-mediated double cleavages on BCR and ABL1 genes as a model for initial event in leukemogenesis.

The Philadelphia (Ph) chromosome was the first translocation identified in leukemia. It is supposed to be generated by aberrant ligation between two DNA double-strand breaks (DSBs) at the BCR gene located on chromosome 9q34 and the ABL1 gene located on chromosome 22q11. Thus, mimicking the initiation process of translocation, we induced CRISPR/Cas9-mediated DSBs simultaneously at the breakpoints of the BCR and ABL1 genes in a granulocyte-macrophage colony-stimulating factor (GM-CSF) dependent human leukemia cell line. After transfection of two single guide RNAs (sgRNAs) targeting intron 13 of the BCR gene and intron 1 of the ABL1 gene, a factor-independent subline was obtained. In the subline, p210 BCR::ABL1 and its reciprocal ABL1::BCR fusions were generated as a result of balanced translocation corresponding to the Ph chromosome. Another set of sgRNAs targeting intron 1 of the BCR gene and intron 1 of the ABL1 gene induced a factor-independent subline expressing p190 BCR::ABL1. Both p210 and p190 BCR::ABL1 induced factor-independent growth by constitutively activating intracellular signaling pathways for transcriptional regulation of cell cycle progression and cell survival that are usually regulated by GM-CSF. These observations suggested that simultaneous DSBs at the BCR and ABL1 gene breakpoints are initiation events for oncogenesis in Ph+ leukemia. (200/200 words).

Pterostilbene downregulates BCR/ABL and induces apoptosis of T315I-mutated BCR/ABL-positive leukemic cells.

In this study, we examined the antileukemic effects of pterostilbene, a natural methylated polyphenol analog of resveratrol that is predominantly found in berries and nuts, using various human and murine leukemic cells, as well as bone marrow samples obtained from patients with leukemia. Pterostilbene administration significantly induced apoptosis of leukemic cells, but not of non-malignant hematopoietic stem/progenitor cells. Interestingly, pterostilbene was highly effective in inducing apoptosis of leukemic cells harboring the BCR/ABL fusion gene, including ABL tyrosine kinase inhibitor (TKI)-resistant cells with the T315I mutation. In BCR/ABL+ leukemic cells, pterostilbene decreased the BCR/ABL fusion protein levels and suppressed AKT and NF-κB activation. We further demonstrated that pterostilbene along with U0126, an inhibitor of the MEK/ERK signaling pathway, synergistically induced apoptosis of BCR/ABL+ cells. Our results further suggest that pterostilbene-promoted downregulation of BCR/ABL involves caspase activation triggered by proteasome inhibition-induced endoplasmic reticulum stress. Moreover, oral administration of pterostilbene significantly suppressed tumor growth in mice transplanted with BCR/ABL+ leukemic cells. Taken together, these results suggest that pterostilbene may hold potential for the treatment of BCR/ABL+ leukemia, in particular for those showing ABL-dependent TKI resistance.

RUNX1 transactivates BCR-ABL1 expression in Philadelphia chromosome positive acute lymphoblastic leukemia.

The emergence of tyrosine kinase inhibitors as part of a front-line treatment has greatly improved the clinical outcome of the patients with Ph+ acute lymphoblastic leukemia (ALL). However, a portion of them still become refractory to the therapy mainly through acquiring mutations in the BCR-ABL1 gene, necessitating a novel strategy to treat tyrosine kinase inhibitor (TKI)-resistant Ph+ ALL cases. In this report, we show evidence that RUNX1 transcription factor stringently controls the expression of BCR-ABL1, which can strategically be targeted by our novel RUNX inhibitor, Chb-M'. Through a series of in vitro experiments, we identified that RUNX1 binds to the promoter of BCR and directly transactivates BCR-ABL1 expression in Ph+ ALL cell lines. These cells showed significantly reduced expression of BCR-ABL1 with suppressed proliferation upon RUNX1 knockdown. Moreover, treatment with Chb-M' consistently downregulated the expression of BCR-ABL1 in these cells and this drug was highly effective even in an imatinib-resistant Ph+ ALL cell line. In good agreement with these findings, forced expression of BCR-ABL1 in these cells conferred relative resistance to Chb-M'. In addition, in vivo experiments with the Ph+ ALL patient-derived xenograft cells showed similar results. In summary, targeting RUNX1 therapeutically in Ph+ ALL cells may lead to overcoming TKI resistance through the transcriptional regulation of BCR-ABL1. Chb-M' could be a novel drug for patients with TKI-resistant refractory Ph+ ALL.

Statins Enhance the Molecular Response in Chronic Myeloid Leukemia when Combined with Tyrosine Kinase Inhibitors.

Previous studies have suggested that statins can be repurposed for cancer treatment. However, the therapeutic efficacy of statins in chronic myeloid leukemia (CML) has not yet been demonstrated. In this study, we retrospectively evaluated the outcomes of 408 CML patients who underwent imatinib therapy. The deep molecular response rates in patients treated with the statin/TKI combination were significantly higher than those in patients treated with TKI alone (p = 0.0016). The statin/TKI combination exerted potent cytotoxic effects against wild-type and ABL1 mutant CML, BaF3, and K562/T315I mutant cells. Furthermore, the statin/TKI combination additively inhibited the colony-forming capacity of murine CML-KLS+ cells in vitro. In addition, we examined the additive growth-inhibitory effects of the statin/tyrosine kinase inhibitor (TKI) combination against CML patient-derived CD34+ cells. The growth-inhibitory effects of the statin/imatinib combination against CD34+/CML primary cells were higher than those against CD34+/Norm cells (p = 0.005), suggesting that the combination of rosuvastatin and imatinib exerted growth-inhibitory effects against CML CD34+ cells, but not against normal CD34+ cells. Furthermore, results from RNA sequencing of control and statin-treated cells suggested that statins inhibited c-Myc-mediated and hematopoietic cell differentiation pathways. Thus, statins can be potentially repurposed to improve treatment outcomes in CML patients when combined with TKI therapy.

Role of Lysophospholipid Metabolism in Chronic Myelogenous Leukemia Stem Cells.

It is well known that mature chronic myelogenous leukemia (CML) cells proliferate in response to oncogenic BCR-ABL1-dependent signaling, but how CML stem cells are able to survive in an oncogene-independent manner and cause disease relapse has long been elusive. Here, I put into the context of the broader literature our recent finding that lysophospholipid metabolism is essential for the maintenance of CML stem cells. I describe the fundamentals of lysophospholipid metabolism and discuss how one of its key enzymes, Glycerophosphodiester Phosphodiesterase Domain Containing 3 (Gdpd3), is responsible for maintaining the unique characteristics of CML stem cells. I also explore how this knowledge may be exploited to devise novel therapies for CML patients.

New routes to eradicating chronic myelogenous leukemia stem cells by targeting metabolism.

Chronic myelogenous leukemia (CML) stem cells are the cellular source of the vast majority of mature CML cells and responsible for relapse of CML disease post-tyrosine kinase inhibitor (TKI) therapy. Although mature CML cells, whose active division is driven by BCR-ABL1 oncogene-dependent signaling, are reduced by TKI therapy, CML stem cells are resistant because they become quiescent via a heretofore elusive mechanism that is independent of oncogene signaling. Recent advances in highly sensitive metabolomics analyses, however, have unveiled new metabolic pathways that are essential for the survival of CML stem cells. With respect to glucose metabolism, CML stem cells elevate anaplerosis to sustain the TCA cycle. Blast crisis (BC)-CML stem cells increase their branched-chained amino acid (BCAA) metabolism. Recently, we showed that CML stem cell quiescence in vivo is regulated by lysophospholipid metabolism that is specific to these cells, namely cooperation between the stemness factors FOXO and ß-catenin. These findings reveal biologically significant links between CML stemness and novel metabolic mechanisms. In this review, I describe these links in the contexts of glucose, amino acid, and lipid metabolism, and speculate on how innovative therapeutics might be designed to eradicate CML stem cells in vivo and overcome disease relapse post-TKI therapy.

KHDRBS3 promotes multi-drug resistance and anchorage-independent growth in colorectal cancer.

5-Fluorouracil (5-FU) is one of the most frequently used pharmacological agents in the treatment of colorectal cancer (CRC). Resistance to chemotherapy is a major cause of treatment failure of CRC, and it is a well known fact that cancer stem cells play a significant role in the acquisition of drug resistance. In this study, we focused on the KHDRBS3 gene that encodes KH RNA Binding Domain Containing, Signal Transduction Associated 3. We first clarified the relationship between KHDRBS3 and 5-FU resistance. We then observed higher expression levels of KHDRBS3 in KRAS-mutant organoids and cell lines in comparison with KRAS wild-type organoids and cell lines. Immunohistochemical analysis using CRC cases revealed that the prognosis of KHDRBS3-positive patients was significantly worse compared with that of KHDRBS3-negative patients. Univariate and multivariate Cox proportional hazards analyses showed that KHDRBS3 was an independent prognostic factor in patients with CRC. We determined that KHDRBS3 might play a crucial role in the acquisition of stem cell properties, such as drug resistance and spheroid/organoid formation, by regulating CD44 variant expression and the Wnt signaling pathway. In an immunodeficient mouse model, KHDRBS3-positive cells showed efficient tumor formation and formed metastatic lesions in the lungs. These results indicated that KHDRBS3 plays a crucial role in drug resistance and anchorage-independent growth by maintaining stem cell-like features in CRC cells. KHDRBS3 could be a promising candidate marker for predicting chemotherapeutic effect and prognosis in CRC patients.

Targeting of plasminogen activator inhibitor-1 activity promotes elimination of chronic myeloid leukemia stem cells.

Therapeutic strategies that target leukemic stem cells (LSCs) provide potential advantages in the treatment of chronic myeloid leukemia (CML). Here, we show that selective blockade of plasminogen activator inhibitor-1 (PAI-1) enhances the susceptibility of CML-LSCs to tyrosine kinase inhibitor (TKI), which facilitates the eradication of CML-LSCs and leads to sustained remission of the disease. We demonstrated for the first time that TGF-ß-PAI-1 axis was selectively augmented in CML-LSCs in the bone marrow (BM), whereby protecting CML-LSCs from TKI treatment. Furthermore, the combined administration of TKI plus a PAI-1 inhibitor, in a mouse model of CML, significantly enhanced the eradication of CML cells in the BM and prolonged the survival of CML mice. The combined therapy of imatinib and a PAI-1 inhibitor prevented the recurrence of CML-like disease in serially transplanted recipients, indicating the elimination of CML-LSCs. Interestingly, PAI-1 inhibitor treatment augmented membrane-type matrix metalloprotease-1 (MT1-MMP)-dependent motility of CML-LSCs, and the anti-CML effect of PAI-1 inhibitor was extinguished by the neutralizing antibody for MT1-MMP, underlining the mechanistic importance of MT1-MMP. Our findings provide evidence of, and a rationale for, a novel therapeutic tactic, based on the blockade of PAI-1 activity, for CML patients.

Molecular biological analysis of 5-FU-resistant gastric cancer organoids; KHDRBS3 contributes to the attainment of features of cancer stem cell.

5-FU is one of the key drugs in the treatment of gastric cancer (GC). Much evidence has shown that cancer stem cells (CSCs) play a key role in the acquisition of drug resistance. The organoid is a novel 3D cell culture system technology that sustains stem-cell-driven formation of near-physiological, self-renewing tissues using specific niche factors in a dish. In this study, we established GC organoids (GCOs) and gradually treated them with higher concentrations of 5-FU. We successfully harvested four 5-FU-resistant GCOs, which were supported by significant changes in the expression of molecules related to 5-FU metabolism. We then performed microarray analysis using three normal gastric organoids and three pairs of 5-FU-resistant and parental GCOs. Through the comparison of expression profiles and further validation, we chose KHDRBS3 as a target gene. We found KHDRBS3 to be an independent prognostic factor in GC patients, especially in GC patients treated with 5-FU chemotherapy. We also determined that KHDRBS3 might play an important role in the acquisition of stem cell-like features, such as multi-drug resistance and organoid formation, by regulating CD44 variant expression. We found KHDRBS3, which is thought to play an important role in the acquisition of characteristics of CSCs in GC, to be a promising candidate marker for predicting therapeutic effect and prognosis in GC patients.

The lysophospholipase D enzyme Gdpd3 is required to maintain chronic myelogenous leukaemia stem cells.

Although advanced lipidomics technology facilitates quantitation of intracellular lipid components, little is known about the regulation of lipid metabolism in cancer cells. Here, we show that disruption of the Gdpd3 gene encoding a lysophospholipase D enzyme significantly decreased self-renewal capacity in murine chronic myelogenous leukaemia (CML) stem cells in vivo. Sophisticated lipidomics analyses revealed that Gdpd3 deficiency reduced levels of certain lysophosphatidic acids (LPAs) and lipid mediators in CML cells. Loss of Gdpd3 also activated AKT/mTORC1 signalling and cell cycle progression while suppressing Foxo3a/ß-catenin interaction within CML stem cell nuclei. Strikingly, CML stem cells carrying a hypomorphic mutation of Lgr4/Gpr48, which encodes a leucine-rich repeat (LRR)-containing G-protein coupled receptor (GPCR) acting downstream of Gdpd3, displayed inadequate disease-initiating capacity in vivo. Our data showing that lysophospholipid metabolism is required for CML stem cell maintenance in vivo establish a new, biologically significant mechanism of cancer recurrence that is independent of oncogene addiction.

Uc.63+ contributes to gastric cancer progression through regulation of NF-kB signaling.

BACKGROUND: The transcribed ultraconserved regions (T-UCRs) are a novel class of long non-coding RNAs and are involved in the development of several types of cancer. Although several different papers have described the oncogenic role of Uc.63+, there are no reports mentioning its importance in gastric cancer (GC) biology. METHODS: In this study, we evaluated Uc.63+ expression using clinical samples of GC by qRT-PCR, and also assessed the correlation between Uc.63+ expression and clinico-pathological factors. RESULTS: The upregulation of Uc.63+ was significantly correlated with advanced clinico-pathological features. Knockdown of Uc.63+ significantly repressed GC cell growth and migration, whereas overexpression of Uc.63+ conversely promoted those of GC cells. In situ hybridization of Uc.63+ revealed its preferential expression in poorly differentiated adenocarcinoma. We further conducted a microarray analysis using MKN-1 cells overexpressing Uc.63- and found that NF-κB signaling was significantly upregulated in accordance with Uc.63+ expression. CONCLUSION: Our results suggest that Uc.63+ could be involved in GC progression by regulating GC cell growth and migration via NF-κB signaling.

HMGCLL1 is a predictive biomarker for deep molecular response to imatinib therapy in chronic myeloid leukemia.

Achieving a deep molecular response (DMR) to tyrosine kinase inhibitor (TKI) therapy for chronic myeloid leukemia (CML) remains challenging and at present, there is no biomarker to predict DMR in this setting. Herein, we report that an HMGCLL1 genetic variant located in 6p12.1 can be used as a predictive genetic biomarker for intrinsic sensitivity to imatinib (IM) therapy. We measured DMR rate according to HMGCLL1 variant in a discovery set of CML patients (n = 201) and successfully replicated it in a validation set (n = 270). We also investigated the functional relevance of HMGCLL1 blockade with respect to response to TKI therapy and showed that small interfering RNA mediated blockade of HMGCLL1 isoform 3 results in significant decrease in viability of BCR-ABL1-positive cells including K562, CML-T1 or BaF3 cell lines with or without ABL1 kinase domain mutations such as T315I mutation. Decreased cell viability was also demonstrated in murine CML stem cells and human hematopoietic progenitor cells. RNA sequencing showed that blockade of HMGCLL1 was associated with G0/G1 arrest and the cell cycle. In summary, the HMGCLL1 gene polymorphism is a novel genetic biomarker for intrinsic sensitivity to IM therapy in CML patients that predicts DMR in this setting.

Metabolic regulation specific to leukemia stem cells.

Leukemia stem cells (LSCs) are responsible for relapse of leukemia. LSCs maintain their self-renewal capacity, stemness properties, and therapeutic resistance in a manner dependent on their cell of origin and genetic alterations acquired during subsequent clonal evolution. Specific mechanisms of metabolic control and nutrient acquisition are implicated in the regulation of LSC survival. Recent advances in gene modification strategies in mice and in sophisticated metabolomics technologies are producing novel inquiries in LSC research performed in vivo. In this review, I examined our current knowledge on the roles of various metabolic pathways, including glucose metabolism, lipid oxidation, and an alternative route of amino acid and peptide supply, that support the maintenance of self-renewal capacity and therapeutic resistance in LSCs in vivo.

Genetic regulation of the RUNX transcription factor family has antitumor effects.

Runt-related transcription factor 1 (RUNX1) is generally considered to function as a tumor suppressor in the development of leukemia, but a growing body of evidence suggests that it has pro-oncogenic properties in acute myeloid leukemia (AML). Here we have demonstrated that the antileukemic effect mediated by RUNX1 depletion is highly dependent on a functional p53-mediated cell death pathway. Increased expression of other RUNX family members, including RUNX2 and RUNX3, compensated for the antitumor effect elicited by RUNX1 silencing, and simultaneous attenuation of all RUNX family members as a cluster led to a much stronger antitumor effect relative to suppression of individual RUNX members. Switching off the RUNX cluster using alkylating agent-conjugated pyrrole-imidazole (PI) polyamides, which were designed to specifically bind to consensus RUNX-binding sequences, was highly effective against AML cells and against several poor-prognosis solid tumors in a xenograft mouse model of AML without notable adverse events. Taken together, these results identify a crucial role for the RUNX cluster in the maintenance and progression of cancer cells and suggest that modulation of the RUNX cluster using the PI polyamide gene-switch technology is a potential strategy to control malignancies.

Regulation of Hematopoiesis and Hematological Disease by TGF-ß Family Signaling Molecules.

Throughout the lifetime of an individual, hematopoietic stem cells (HSCs) maintain the homeostasis of normal hematopoiesis through the precise generation of mature blood cells. Numerous genetic studies in mice have shown that stem-cell quiescence is critical for sustaining primitive long-term HSCs in vivo. In this review, we first examine the crucial roles of transforming growth factor ß (TGF-ß) and related signaling molecules in not only regulating the well-known cytostatic effects of these molecules but also governing the self-renewal capacity of HSCs in their in vivo microenvironmental niche. Second, we discuss the current evidence indicating that TGF-ß signaling has a dual function in disorders of the hematopoietic system. In particular, we examine the paradox that, although intrinsic TGF-ß signaling is essential for regulating the survival and resistance to therapy of chronic myelogenous leukemia (CML) stem cells, genetic changes that abrogate TGF-ß signaling can lead to the development of several hematological malignancies.

Immunological Analyses of Leukemia Stem Cells.

Traditionally, the intracellular localization and expression levels of specific proteins in CML Leukemia stem cells (LSCs) have been evaluated by fluorescence immunohistochemistry (FIHC). More recently, Duolink(®) in situ PLA technology has opened up a new and more quantitative way to evaluate signal transduction, posttranslational modification, and protein-protein interaction at the single-stem-cell level. This novel methodology, which employs two antibody-based probes, has already increased our understanding of the biology of the rare CML LSC population. In the future, the use of this approach may contribute to the development of novel therapeutics aimed at eradicating CML LSCs in CML patients.

New hope for chronic myelogenous leukemia patients: dasatinib offers better efficacy with shorter treatment.

Although the discovery of tyrosine kinase inhibitors (TKIs) has dramatically improved the prognoses of chronic myelogenous leukemia (CML) patients, a cure has remained elusive. Unanswered questions include how long must a patient continue on TKI therapy, and how does a patient know when he/she can safely stop or finish this therapy? Imagawa et al. have carefully addressed these questions of safety and efficacy using a stop study of the second-generation TKI dasatinib. The results of a multicenter phase II trial termed the "dasatinib discontinuation" (DADI) trial indicated that 48% (30/63) of CML patients who had maintained a deep molecular response (DMR) to second-line or subsequent dasatinib therapy for at least for 1 year did not show any signs of disease relapse. Thus, even after it is stopped, dasatinib treatment may decrease the chance of disease relapse and provide a curative benefit to CML patients. This work by Imagawa et al. strongly supports the clinical utility of the second-generation TKI dasatinib for CML treatment.

Manipulation of Cell Cycle and Chromatin Configuration by Means of Cell-Penetrating Geminin.

Geminin regulates chromatin remodeling and DNA replication licensing which play an important role in regulating cellular proliferation and differentiation. Transcription of the Geminin gene is regulated via an E2F-responsive region, while the protein is being closely regulated by the ubiquitin-proteasome system. Our objective was to directly transduce Geminin protein into cells. Recombinant cell-penetrating Geminin (CP-Geminin) was generated by fusing Geminin with a membrane translocating motif from FGF4 and was efficiently incorporated into NIH 3T3 cells and mouse embryonic fibroblasts. The withdrawal study indicated that incorporated CP-Geminin was quickly reduced after removal from medium. We confirmed CP-Geminin was imported into the nucleus after incorporation and also that the incorporated CP-Geminin directly interacted with Cdt1 or Brahma/Brg1 as the same manner as Geminin. We further demonstrated that incorporated CP-Geminin suppressed S-phase progression of the cell cycle and reduced nuclease accessibility in the chromatin, probably through suppression of chromatin remodeling, indicating that CP-Geminin constitutes a novel tool for controlling chromatin configuration and the cell cycle. Since Geminin has been shown to be involved in regulation of stem cells and cancer cells, CP-Geminin is expected to be useful for elucidating the role of Geminin in stem cells and cancer cells, and for manipulating their activity.