Discovery of a Novel Chemical Scaffold Against Mutant Isocitrate Dehydrogenase 1 (IDH1).

BACKGROUND: Mutations in the isocitrate dehydrogenase 1 (IDH1) gene are frequently found in various cancer types. IDH1 mutants produce 2-hydroxyglutarate (2-HG), an oncometabolite, from alpha-ketoglutarate (α-KG). This 2-HG plays a key role in tumorigenesis via inhibition of α-KG dependent enzymes. For this reason, IDH1 mutant could be an ideal target for the treatment of cancer. MATERIALS AND METHODS: To find a new IDH1 inhibitor, 8,364 compounds were obtained from Korea Chemical Bank. Using high-throughput screening (HTS) of a chemical library, we unveiled a compound that could inhibit the IDH1 mutant. RESULTS: According to the enzyme assay, our compound (KRC-09) effectively inhibited the activity of IDH1 R132H mutant. In addition, KRC-09 decreased the concentration of intracellular 2-HG in the U-87 MG cell line harboring IDH1 R132H. CONCLUSION: In this article, we present a novel chemical scaffold that suppresses the activity of an IDH1 mutant.

Novel nickel(II), palladium(II), and platinum(II) complexes having a pyrrolyl-iminophosphine (PNN) pincer: Synthesis, crystal structures, and cytotoxic activity.

A pyrrolyl-iminophosphine (PNNH) which would act as a potential terdentate ligand has been prepared by Schiff base reaction. Complexes [M(PNN)X] (M = Ni; X = Cl (1), Pd; X = Cl (2), Br (3), I (4), M = Pt; X = Cl (5)) were prepared. The title complexes were characterized by various spectroscopic (IR, 1H, 13C, and 31P NMR) and elemental analyses. The molecular structures of 1, 2, and 5 have been established by single-crystal X-ray crystallography, demonstrating a distorted square planar geometry comprising two 5-membered metallacyclic rings. Complexes 1 and 2 were found to crystallize in the orthorhombic while complex 5 crystallizes in the monoclinic. Cytotoxicities of the complexes along with PNNH were evaluated against A549 (lung), SK-OV-3 (ovarian), SM-MEL-2 (skin), and HCT15 (colon) human cancer cell lines by sulforhodamine B assay. Notably, the palladium(II) complex (2) shows the highest activity. Apoptosis activity along with the caspase inhibitor Z-VAD (Z-Val-Ala-Asp-fluoromethyl ketone) assay of 2 and 5 against A549 and HCT15 cancer cell lines were investigated to learn a mechanistic pathway for the observed cytotoxicity, practically eliminating an apoptotic cell-death route. Complexes 2 and 5 were studied to DNA cleavage assay and molecular docking simulation. The DNA (pcDNA3.0) cleavage experiment evaluates complex 5 interacting with DNA, more effectively, in comparison to complex 2. Molecular docking simulation of 2 and 5 toward DNA and GRP78 (glucose-regulated protein 78) was performed to predict binding sites of ligand-receptors and a plausible mechanistic aspect of metallodrug-action.

Discovery of indirubin derivatives as new class of DRAK2 inhibitors from high throughput screening.

DRAK2 is a serine/threonine kinase belonging to the death-associated protein kinase (DAPK) family and has emerged as a promising drug target for the treatment of autoimmune diseases and cancers. To identify small molecule inhibitors for DRAK2, we performed a high throughput screening campaign using in-house chemical library and identified indirubin-3'-monoximes as novel class of DRAK2 inhibitors. Among the compounds tested, compound 16 exhibited the most potent inhibitory activity against DRAK2 (IC50=0.003µM). We also propose that compound 16 may bind to the ATP-binding site of the enzyme based on enzyme kinetics and molecular docking studies.

Minor modifications to ceritinib enhance anti-tumor activity in EML4-ALK positive cancer.

Ceritinib, an ALK inhibitor, was hurriedly approved by the US FDA last year, and demonstrates impressive results in EML4-ALK positive patients. To get a superior ALK inhibitor, we synthesized several ceritinib derivatives with minor modifications to the phenylpiperidine moiety. Biochemical and cellular assays demonstrated the improved activity of KRCA-386 over that of ceritinib. KRCA-386 has superior inhibitory activity against ALK mutants commonly found in crizotinib-resistant patients. Particularly, KRCA-386 has considerably greater activity than ceritinib against the G1202R mutant, one of the most challenging mutations to overcome. The cell cycle analysis indicates that ALK inhibitors induce G1/S arrest, resulting in apoptosis. The in vivo xenograft data also demonstrate that KRCA-386 is significantly better than ceritinib. KRCA-386 dosed at 25 mpk caused 105% tumor growth inhibition (TGI) compared to 72% TGI with ceritinib dosed at 25 mpk. (n = 8, P = 0.010) The kinase profiling assay revealed that several kinases, which are known to be critical for tumor growth, are inhibited by KRCA-386, but not by ceritinib. We anticipate that this characteristic of KRCA-386 enhances its in vivo efficacy. In addition, KRCA-386 shows excellent blood brain barrier penetration compared to ceritinib. These results suggest that KRCA-386 could be useful for crizotinib-resistant patients with brain metastases.

Regulation of Adipocyte Differentiation via MicroRNAs.

Adipocyte differentiation, termed adipogenesis, is a complicated process in which pluripotent mesenchymal stem cells differentiate into mature adipocytes. The process of adipocyte differentiation is tightly regulated by a number of transcription factors, hormones and signaling pathway molecules. Recent studies have demonstrated that microRNAs, which belong to small noncoding RNA species, are also involved in adipocyte differentiation. In vivo and in vitro studies have revealed that various microRNAs affect adipogenesis by targeting several adipogenic transcription factors and key signaling molecules. In this review, we will summarize the roles of microRNAs in adipogenesis and their target genes associated with each stage of adipocyte differentiation.

A novel 11ß-HSD1 inhibitor improves diabesity and osteoblast differentiation.

Selective inhibitors of 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) have considerable potential as treatment for osteoporosis as well as metabolic syndrome including type 2 diabetes mellitus. Here, we investigated the anti-diabetic, anti-adipogenic, and anti-osteoporotic activity of KR-67500, as a novel selective 11ß-HSD1 inhibitor. Cellular 11ß-HSD1 activity was tested based on a homogeneous time-resolved fluorescence method. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) levels were measured in diet-induced obese (DIO)-C57BL/6 mice administered KR-67500 (50  mg/kg per day, p.o.) for 28 days and, additionally, its anti-diabetic effect was evaluated by OGTT and ITT. The in vitro anti-adipogenic effect of KR-67500 was determined by Oil Red O Staining. The in vitro anti-osteoporotic activity of KR-67500 was evaluated using bone morphogenetic protein 2 (BMP2)-induced osteoblast differentiation and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation model systems. KR-67500 improved the in vivo glucose tolerance and insulin sensitivity in DIO-C57BL/6 mice. KR-67500 suppressed cortisone-induced differentiation of 3T3-L1 cells into adipocytes. KR-67500 enhanced BMP2-induced osteoblastogenesis in C2C12 cells and inhibited RANKL-induced osteoclastogenesis in mouse bone marrow-derived macrophages. KR-67500, a new selective 11ß-HSD1 inhibitor, may provide a new therapeutic window in the prevention and/or treatment of type 2 diabetes, obesity, and/or osteoporosis.

The protein kinase 2 inhibitor CX-4945 regulates osteoclast and osteoblast differentiation in vitro.

Drug repositioning can identify new therapeutic applications for existing drugs, thus mitigating high R&D costs. The Protein kinase 2 (CK2) inhibitor CX-4945 regulates human cancer cell survival and angiogenesis. Here we found that CX-4945 significantly inhibited the RANKL-induced osteoclast differentiation, but enhanced the BMP2-induced osteoblast differentiation in a cell culture model. CX-4945 inhibited the RANKL-induced activation of TRAP and NFATc1 expression accompanied with suppression of Akt phosphorylation, but in contrast, it enhanced the BMP2-mediated ALP induction and MAPK ERK1/2 phosphorylation. CX-4945 is thus a novel drug candidate for bone-related disorders such as osteoporosis.

Pharmacokinetic characterization of CK2 inhibitor CX-4945.

Over-expression of protein kinase CK2 is highly linked to the survival of cancer cells and the poor prognosis of patients with cancers. CX-4945, a potent and selective orally bioavailable ATP-competitive inhibitor of CK2, inhibits the oncogenic cellular events such as proliferation and angiogenesis, and the increase of tumor growth in mouse xenograft model. In this study, the pharmacokinetic information about CX-4945 was provided; at 10 µM, CX-4945 with high stability in human and rat liver microsome exhibited low percentage of inhibition (<10 %) in CYP450 isoforms (1A2, 2C19, 3A4), but considerable inhibition (~70 %) in CYP450 2C9 and 2D6. In hERG potassium channel inhibition assay, CX-4945 exhibited relatively low inhibition rate. Additionally, CX-4945 showed high MDCK cell permeability (>10 × 10(-6) cm/s) and above 98 % of plasma protein binding in the rat. After intravenous administration, Vss (1.39 l/kg) and extremely low CL (0.08 l/kg/h) were observed. Moreover, orally administrated CX-4945 showed high bioavailability (>70 %) and these data might be related to the MDCK cell permeability results.

miR-27a is a negative regulator of adipocyte differentiation via suppressing PPARgamma expression.

microRNAs (miRNAs) are non-coding small RNAs regulating gene expression, cell growth, and differentiation. Although several miRNAs have been implicated in cell growth and differentiation, it is barely understood their roles in adipocyte differentiation. In the present study, we reveal that miR-27a is involved in adipocyte differentiation by binding to the PPARgamma 3'-UTR whose sequence motifs are highly conserved in mammals. During adipogenesis, the expression level of miR-27a was inversely correlated with that of adipogenic marker genes such as PPARgamma and adiponectin. In white adipose tissue, miR-27a was more abundantly expressed in stromal vascular cell fraction than in mature adipocyte fraction. Ectopic expression of miR-27a in 3T3-L1 pre-adipocytes repressed adipocyte differentiation by reducing PPARgamma expression. Interestingly, the level of miR-27a in mature adipocyte fraction of obese mice was down-regulated than that of lean mice. Together, these results suggest that miR-27a would suppress adipocyte differentiation through targeting PPARgamma and thereby down-regulation of miR-27a might be associated with adipose tissue dysregulation in obesity.