Small Molecule Induces Time-Dependent Inhibition of Stat3 Dimerization and DNA-Binding Activity and Regresses Human Breast Tumor Xenografts.

Aberrantly-active signal transducer and activator of transcription (Stat)3 has a causal role in many human cancers and represents a validated anticancer drug target, though it has posed significant challenge to drug development. A new small molecule, JKB887, was identified through library screening and is predicted to interact with Lys591, Arg609 and Pro63 in the phospho-tyrosine (pTyr)-binding pocket of the Stat3 SH2 domain. JKB887 inhibited Stat3 DNA-binding activity in vitro in a time-dependent manner, with IC of 2.

Integration of fingerprint-based similarity searching and kernel-based partial least squares analysis to predict inhibitory activity against CSK, HER2, JAK1, JAK2, and JAK3.

Fingerprint-based similarity searching is an important strategy for virtual screening in drug discovery. In the present study, we carried out a systematic virtual screening study, followed by the establishment of kernel-based partial least square (KPLS) analysis prediction models for five tyrosine kinase drug targets, C-terminal SRC kinase (CSK), human epidermal growth factor 2 (HER2), and Janus kinases 1, 2, and 3 (JAK1, JAK2, and JAK3), using a dataset of 3688 compounds. These kinases are important drug discovery targets, particularly as HER2 has been validated for the treatment of metastatic breast cancer, JAK inhibitors have been validated for the clinical management of arthritis and autoimmune diseases, and CSK has been found to play an important role in bone remodeling in arthritis.

SS-4 is a highly selective small molecule inhibitor of STAT3 tyrosine phosphorylation that potently inhibits GBM tumorigenesis in vitro and in vivo.

Glioblastoma (GBM) is a highly aggressive cancer with a dismal prognosis. Constitutively active STAT3 has a causal role in GBM progression and is associated with poor patient survival. We rationally designed a novel small molecule, SS-4, by computational modeling to specifically interact with STAT3.

Targeting MDM2 for Neuroblastoma Therapy: In Vitro and In Vivo Anticancer Activity and Mechanism of Action.

Background: Neuroblastoma is an aggressive pediatric solid tumor with an overall survival rate of <50% for patients with high-risk disease. The majority (>98%) of pathologically-diagnosed neuroblastomas have wild-type p53 with intact functional activity. However, the mouse double minute 2 (MDM2) homolog, an E3 ubiquitin ligase, is overexpressed in neuroblastoma and leads to inhibition of p53.

Targeted Brain Tumor Therapy by Inhibiting the MDM2 Oncogene: In Vitro and In Vivo Antitumor Activity and Mechanism of Action.

There is a desperate need for novel and efficacious chemotherapeutic strategies for human brain cancers. There are abundant molecular alterations along the p53 and MDM2 pathways in human glioma, which play critical roles in drug resistance. The present study was designed to evaluate the in vitro and in vivo antitumor activity of a novel brain-penetrating small molecule MDM2 degrader, termed SP-141.

A novel RNA variant of human concentrative nucleoside transporter 1 (hCNT1) that is a potential cancer biomarker.

Background: The human concentrative nucleoside transporter 1 (hCNT1) a product of the  gene is one of the three concentrative nucleoside transporters, with a substrate specificity for physiological pyrimidine nucleosides. It has recently been implicated in tumor suppression. We have unraveled a splice variant RNA transcript that is overexpressed in some tumor tissues and some cancer cells.

QSAR Studies of New Pyrido[3,4-]indole Derivatives as Inhibitors of Colon and Pancreatic Cancer Cell Proliferation.

We have discovered a new class of pyrido[]bindole derivatives that show potent and broad spectrum anticancer activity with IC values down to submicromolar levels. Structure-activity relationship data acquired with the compounds as antiproliferative agents against several cancer cell lines, i.e.

Inhibiting β-Catenin by β-Carboline-Type MDM2 Inhibitor for Pancreatic Cancer Therapy.

The β-catenin and MDM2 oncoproteins are overexpressed and constitutively activated in human pancreatic cancer and contribute to its initiation, progression, and metastasis. The Wnt/β-catenin signaling pathway strongly interacts with the MDM2-p53 signaling pathway, accelerating the tumorigenesis and its development. Therefore, therapies inhibiting both β-catenin and MDM2 are suggested to be ideal treatments for patients with advanced pancreatic cancer.

Synthesis, Biological Evaluation and Modeling Studies of New Pyrido[3,4-]indole Derivatives as Broad-Spectrum Potent Anticancer Agents.

Objective: There is an urgent need drugs against particularly difficult to treat solid tumors such as pancreatic, triple negative breast, lung, colon, metastatic prostate cancers and melanoma. Thus, the objective of this study was to synthesize compounds based computational modeling that indicated the pyrido[3,4-]indole class bind to MDM2, a new cancer target for which there are still no drug on the market.

Methods: Compounds were synthesized by established methods and tested for antiproliferative activity against a broad range of human cancer cell lines, comprising HCT116 colon, HPAC, MIA PaCa-2 and Panc-1 pancreatic, MCF-7 and MDA-MB-468 breast, A375 and WM164 melanoma, A549 lung, and LNCaP, DU145 and PC3 prostate cancer lines.

Homology Modeling of Human Concentrative Nucleoside Transporters (hCNTs) and Validation by Virtual Screening and Experimental Testing to Identify Novel hCNT1 Inhibitors.

Objective: The nucleoside transporter family is an emerging target for cancer, viral and cardiovascular diseases. Due to the difficulty in the expression, isolation and crystallization of membrane proteins, there is a lack of structural information on any of the mammalian and for that matter the human proteins. Thus the objective of this study was to build homology models for the three cloned concentrative nucleoside transporters hCNT1, hCNT2 and hCNT3 and validate them for screening towards the discovery of much needed inhibitors and probes.

Dilazep analogues for the study of equilibrative nucleoside transporters 1 and 2 (ENT1 and ENT2).

As ENT inhibitors including dilazep have shown efficacy improving oHSV1 targeted oncolytic cancer therapy, a series of dilazep analogues was synthesized and biologically evaluated to examine both ENT1 and ENT2 inhibition. The central diamine core, alkyl chains, ester linkage and substituents on the phenyl ring were all varied. Compounds were screened against ENT1 and ENT2 using a radio-ligand cell-based assay.

Development and validation of a rapid HPLC method for quantitation of SP-141, a novel pyrido[b]indole anticancer agent, and an initial pharmacokinetic study in mice.

There is an increasing interest in targeting the MDM2 oncogene for cancer therapy. SP-141, a novel designed small molecule MDM2 inhibitor, exerts excellent in vitro and in vivo anticancer activity. To facilitate the preclinical development of this candidate anticancer agent, we have developed an HPLC method for the quantitative analysis of SP-141.

The pyrido[b]indole MDM2 inhibitor SP-141 exerts potent therapeutic effects in breast cancer models.

A requirement for Mouse Double Minute 2 (MDM2) oncogene activation has been suggested to be associated with cancer progression and metastasis, including breast cancer. To date, most MDM2 inhibitors have been designed to block the MDM2-p53-binding interphase, and have low or no efficacy against advanced breast cancer with mutant or deficient p53. Here we use a high-throughput screening and computer-aided, structure-based rational drug design, and identify a lead compound, SP-141, which can directly bind to MDM2, inhibit MDM2 expression and induce its autoubiquitination and proteasomal degradation.

A quantitative LC-MS/MS method for determination of SP-141, a novel pyrido[b]indole anticancer agent, and its application to a mouse PK study.

In the present study, a specific and sensitive liquid chromatography-triple quadrupole mass spectrometry method was developed and validated for the determination of SP-141, a novel pyrido[b]indole anticancer agent. After a liquid-liquid extraction with n-hexane-dichloromethane-2-propanol (20:10:1, v/v/v) mixture, the analyte was separated on a Kinetex C18 column (50×2.1mm, 2.

Identification of a new class of MDM2 inhibitor that inhibits growth of orthotopic pancreatic tumors in mice.

Background & Aims: The oncogene MDM2, which encodes an E3 ubiquitin ligase, is overexpressed in pancreatic cancers and is therefore a therapeutic target. Current inhibitors of MDM2 target the interaction between MDM2 and P53; these would have no effect on cancer cells that do not express full-length P53, including many pancreatic cancer cells. We searched for a compound that specifically inhibits MDM2 itself.

Impact of resistance mutations on inhibitor binding to HIV-1 integrase.

HIV-1 integrase (IN) is essential for HIV-1 replication, catalyzing two key reaction steps termed 3' processing and strand transfer. Therefore, IN has become an important target for antiviral drug discovery. However, mutants have emerged, such as E92Q/N155H and G140S/Q148H, which confer resistance to raltegravir (RAL), the first IN strand transfer inhibitor (INSTI) approved by the FDA, and to the recently approved elvitegravir (EVG).

Synthesis, docking, and biological studies of phenanthrene β-diketo acids as novel HIV-1 integrase inhibitors.

In the present study we report the synthesis of halogen-substituted phenanthrene β-diketo acids as new HIV-1 integrase inhibitors. The target phenanthrenes were obtained using both standard thermal- and microwave-assisted synthesis. 4-(6-Chlorophenanthren-2-yl)-2,4-dioxobutanoic acid (18) was the most active compound of the series, inhibiting both 3'-end processing (3'-P) and strand transfer (ST) with IC50 values of 5 and 1.

Dipyridamole analogs as pharmacological inhibitors of equilibrative nucleoside transporters. Identification of novel potent and selective inhibitors of the adenosine transporter function of human equilibrative nucleoside transporter 4 (hENT4).

To identify needed human equilibrative nucleoside transporter 4 (hENT4) inhibitors, we cloned and stably expressed the recombinant protein in PK15NTD (nucleoside transporter deficient) cells, and, investigated its interaction with a series of dipyridamole analogs synthesized in our laboratory. Compounds were tested in this newly established hENT4 expressing system as well in previous stably expressed hENT1 and hENT2 expressing systems. Of the dipyridamole analogs evaluated, about one fourth of the compounds inhibited hENT4 with higher potencies than dipyridamole.

Chemoprevention activity of dipyridamole in the MMTV-PyMT transgenic mouse model of breast cancer.

Dipyridamole (DPM) is widely used to prevent strokes and vascular thrombosis. Combination therapy of DPM and antimetabolites has shown synergistic anticancer activity. This study investigated the chemopreventive effects of DPM in the mouse mammary tumor virus promoter-driven polyoma middle T oncoprotein metastatic breast cancer model.

Inhibition of gastric tumor growth by a novel Hsp90 inhibitor.

Heat shock protein 90 (Hsp90) is a molecular chaperone engaging in multiple cellular signaling by stabilizing oncoproteins (e.g. Akt and c-Raf) in tumor cells.

JKA97, a novel benzylidene analog of harmine, exerts anti-cancer effects by inducing G1 arrest, apoptosis, and p53-independent up-regulation of p21.

JKA97, a benzylidene analog of harmine, has been found to be a promising drug candidate for human cancer therapy, although the underlying molecular mechanisms have not been fully demonstrated. In this study, we evaluated the effects of JKA97 on human breast cancer cells in vitro and in vivo. JKA97 inhibited the growth and proliferation of MCF7 (p53 wild-type), MCF7 (p53 knockdown), and MDA-MB-468 (p53 mutant) cells in a dose-dependent manner.

Homology model-guided 3D-QSAR studies of HIV-1 integrase inhibitors.

In the present study, we report the exploration of binding modes of potent HIV-1 integrase (IN) inhibitors MK-0518 (raltegravir) and GS-9137 (elvitegravir) as well as chalcone and related amide IN inhibitors we recently synthesized and the development of 3D-QSAR models for integrase inhibition. Homology models of DNA-bound HIV-1 IN were constructed on the basis of the X-ray crystal structure of the foamy virus IN-DNA complex (PDB ID: 3L2T ) and used for docking. The binding modes of raltegravir and elvitegravir in our homology models are in accordance with those in the foamy virus structure revealing interactions important for inhibitor-IN binding.

Design, synthesis, and evaluation of 2-diethanolamino-4,8-diheptamethyleneimino-2-(N-aminoethyl-N-ethanolamino)-6-(N,N-diethanolamino)pyrimido[5,4-d]pyrimidine-fluorescein conjugate (8MDP-fluor), as a novel equilibrative nucleoside transporter probe.

Nucleoside transporters are integral membrane glycoproteins that play critical roles in physiological nucleoside and nucleobase fluxes, and influence the efficacy of many nucleoside chemotherapy drugs. Fluorescent reporter ligands/substrates have been shown to be useful in the analysis of nucleoside transporter (NT) protein expression and discovery of new NT inhibitors. In this study, we have developed a novel dipyridamole (DP)-based equilibrative nucleoside transporter 1 (ENT1) fluorescent probe.

Synthesis, biological evaluation and 3D-QSAR studies of 3-keto salicylic acid chalcones and related amides as novel HIV-1 integrase inhibitors.

HIV-1 integrase is one of the three most important enzymes required for viral replication and is therefore an attractive target for anti retroviral therapy. We herein report the design and synthesis of 3-keto salicylic acid chalcone derivatives as novel HIV-1 integrase inhibitors. The most active compound, 5-bromo-2-hydroxy-3-[3-(2,3,6-trichlorophenyl)acryloyl]benzoic acid (25) was selectively active against integrase strand transfer, with an IC(50) of 3.

A small-molecule inhibitor of MDMX activates p53 and induces apoptosis.

The p53 inactivation caused by aberrant expression of its major regulators (e.g., MDM2 and MDMX) contributes to the genesis of a large number of human cancers.