Recent development of anticancer therapeutics targeting Akt

Antitumor effect of trimetazidine in a model of solid Ehrlich carcinoma is mediated by inhibition of glycolytic pathway and AKT signaling

Disturbance in glucose metabolism was proposed to be a pathogenetic mechanism of breast cancer. Trimetazidine (TMZ) inhibits β-oxidation of fatty acids through blocking the activity of 3-ketoacylCoA thiolase enzyme, leading to enhancement of glucose oxidation and metabolic respiration. The present study aimed to examine the cytotoxic effect of TMZ in both in vivo and in vitro models of breast cancer, focusing on its impact on the expression of some glycolytic enzymes and AKT signaling. The cytotoxic effect of TMZ was screened against breast (MCF-7) cancer cell line at different concentrations [0.01-100 μM]. In vivo, graded doses (10, 20, 30 mg/kg) of TMZ were tested against solid Ehrlich carcinoma (SEC) in mice. Tumor tissues were isolated for assessment of the expression of glucose transporter-1 (GLUT-1) and glycolytic enzymes by quantitative PCR. The protein expression of AKT and cellular myelocytomatosis (c-Myc) was determined by western blotting, while p53 expression was evaluated by immunohistochemistry. Molecular docking study of TMZ effect on AKT and c-Myc was performed using Auto-Dock Vina docking program. TMZ showed a cytotoxic action against MCF-7 cells, having IC50 value of 2.95 μM. In vivo, TMZ reduced tumor weight, downregulated the expression of glycolytic enzymes, suppressed AKT signaling, but increased p53 expression. Molecular docking and in silico studies proposed that TMZ is an AKT and c-Myc selective inhibitor. In conclusion, TMZ demonstrated a viable approach to suppress tumor proliferation in biological models of breast cancer.

Interfering with the Ubiquitin-Mediated Regulation of Akt as a Strategy for Cancer Treatment

The serine/threonine kinase Akt modulates the functions of numerous substrates, many of them being involved in cell proliferation and growth, metabolism, angiogenesis, resistance to hypoxia and migration. Akt is frequently deregulated in many types of human cancers, its overexpression or abnormal activation being associated with the increased proliferation and survival of cancer cells. A promising avenue for turning off the functionality of Akt is to either interfere with the K63-linked ubiquitination that is necessary for Akt membrane recruitment and activation or increase the K48-linked polyubiquitination that aims to target Akt to the proteasome for its degradation. Recent evidence indicates that targeting the ubiquitin proteasome system is effective for certain cancer treatments. In this review, the functions and roles of Akt in human cancer will be discussed, with a main focus on molecules and compounds that target various elements of the ubiquitination processes that regulate the activation and inactivation of Akt. Moreover, their possible and attractive implications for cancer therapy will be discussed.

C-demethylation and 1, 2-amino shift in (E)-2-(1-(3-aminophenyl) ethylidene)hydrazinecarboxamide to (E)-2-(2-aminobenzylidene)hydrazinecarboxamide and their applications

A Novel (E)-2-(1-(3-aminophenyl)ethylidene)hydrazinecarboxamide 1 was synthesized by traditional method and converted to (E)-2-(2-aminobenzylidene)hydrazinecarboxamide 2 by single step in DMSO at room temperature. Synthesized compound 1 was analysed by spectroscopy (NMR and LC–MS) techniques and molecule 2 was characterized using single crystal X-ray diffraction and spectroscopy (NMR and GC–MS) techniques. These analytical technique results revealed that, C-demethylation and 1, 2 amino shift in phenyl ring of compound 1 gives molecule 2. DNA binding studies of compounds 1 and 2 was carried out by electronic absorption spectroscopy. This result revealed that, compounds 1 and 2 showed hyperchromism with bathochromic shift. Anticancer activity of compounds 1 and 2 is carried out by molecular docking with five receptors.Computer aided virtual screening demonstrated that the synthesized molecules possess ideal drug likeliness, pharmacokinetics features, toxicity profile for structure based drug discovery. The molecular docking studies revealed that the synthesized molecules are significant binding with the five selected cancer receptors with minimum binding energy (kcal/mol), number of hydrogen bonds, weak interaction, docking score and cluster RMS. The docking studies also suggested that the molecules showed interactions with DNA and the theoretical values of the binding are comparable with that of the experimental values. Hirshfeld surface analysis was used to analyze and quantify the intermolecular interactions in the crystal structure of compound 2.

Design, Synthesis, In vitro and In silico Evaluation of New Hydrazonebased Antitumor Agents as Potent Akt Inhibitors

Background:

Akt is overexpressed or activated in a variety of human cancers, including gliomas, lung, breast, ovarian, gastric and pancreatic carcinomas. Akt inhibition leads to the induction of apoptosis and inhibition of tumor growth and therefore extensive efforts have been devoted to the discovery of potent antitumor drugs targeting Akt.

Objectives:

The objective of this work was to identify potent anticancer agents targeting Akt.

Methods:

New hydrazone derivatives were synthesized and investigated for their cytotoxic effects on 5RP7 H-ras oncogene transformed rat embryonic fibroblast and L929 mouse embryonic fibroblast cell lines. Besides, the apoptotic effects of the most active compounds on 5RP7 cell line were evaluated using flow cytometry. Their Akt inhibitory effects were also investigated using a colorimetric assay. In silico docking and Absorption, Distribution, Metabolism and Excretion (ADME) studies were also performed using Schrödinger’s Maestro molecular modeling package.

Results and Discussion:

Compounds 3a, 3d, 3g and 3j were found to be effective on 5RP7 cells (with IC50 values of <0.97, <0.97, 1.13±0.06 and <0.97 μg/mL, respectively) when compared with cisplatin (IC50= 1.87±0.15 μg/mL). It was determined that these four compounds significantly induced apoptosis in 5RP7 cell line. Among them, N'-benzylidene-2-[(4-(4-methoxyphenyl)pyrimidin- 2-yl)thio]acetohydrazide (3g) significantly inhibited Akt (IC50= 0.5±0.08 μg/mL) when compared with GSK690693 (IC50= 0.6±0.05 μg/mL). Docking studies suggested that compound 3g showed good affinity to the active site of Akt (PDB code: 2JDO). According to in silico ADME studies, the compound also complies with Lipinski's rule of five and Jorgensen's rule of three.

Conclusion:

Compound 3g stands out as a potential orally bioavailable cytotoxic agent and apoptosis inducer targeting Akt.

Synthesis, In Silico and In Vitro Assessment of New Quinazolinones as Anticancer Agents via Potential AKT Inhibition

A series of novel quinazolinone derivatives (2–13) was synthesized and examined for their cytotoxicity to HepG2, MCF-7, and Caco-2 in an MTT assay. Among these derivatives, compounds 4 and 9 exhibited significant cytotoxic activity against Caco-2, HepG2, and MCF-7 cancer cells. Compound 4 had more significant inhibitory effects than compound 9 on Caco-2, HepG2, and MCF-7 cell lines, with IC₅₀ values of 23.31 ± 0.09, 53.29 ± 0.25, and 72.22 ± 0.14µM, respectively. The AKT pathway is one of human cancer’s most often deregulated signals. AKT is also overexpressed in human cancers such as glioma, lung, breast, ovarian, gastric, and pancreas. A molecular docking study was performed to analyze the inhibitory action of newly synthetic quinazolinone derivatives against Homo sapiens AKT1 protein. Molecular docking simulations were found to be in accordance with in vitro studies, and hence supported the biological activity. The results suggested that compounds 4 and 9 could be used as drug candidates for cancer therapy via its potential inhibition of AKT1 as described by docking study.

The Phenoxyphenol Compound 4-HPPP Selectively Induces Antiproliferation Effects and Apoptosis in Human Lung Cancer Cells through Aneupolyploidization and ATR DNA Repair Signaling

Lung cancer is a leading cause of cancer death worldwide, and non-small-cell lung cancer (NSCLC) accounts for 85% of lung cancer, which is highly metastatic, leading to the poor survival rate of patients. We recently reported that 4-[4-(4-hydroxyphenoxy)phenoxy]phenol (4-HPPP), a phenoxyphenol, exerts antihepatoma effects by inducing apoptosis and autophagy. In this study, we further examined the effect of 4-HPPP and its analogs on NSCLC cells. Colony formation assays showed that 4-HPPP exerts selective cytotoxicity against NSCLC H1299 cells; furthermore, the inhibitory effect of 4-HPPP on the proliferation and migration of NSCLC cells was validated using an in vivo zebrafish-based tumor xenograft assay. The flow cytometry-based dichlorofluorescein diacetate (DCF-DA) assays indicated that 4-HPPP caused an increase in reactive oxygen species (ROS) in NSCLC cells, and Western blot assays showed that the major ROS scavenging enzymes superoxide dismutases- (SODs-) 1/2 were upregulated, whereas peroxidase (PRX) was downregulated. Furthermore, 4-HPPP caused both aneuploidization and the accumulation of γH2AX, a sensor of DNA damage, as well as the activation of double-strand break (DSB) markers, especially Ataxia-telangiectasia-mutated and Rad3-related (ATR) in NSCLC cells. Our present work suggests that the antiproliferative effects of 4-HPPP on lung cancer cells could be due to its phenoxyphenol structure, and 4-HPPP could be a candidate molecule for treating NSCLC by modulating ROS levels and lowering the threshold of polyploidy-specific cell death in the future.

Exploring receptor tyrosine kinases-inhibitors in Cancer treatments

Background

Receptor tyrosine kinases (RTKs) are signaling enzymes responsible for the transfer of Adenosine triphosphate (ATP) γ-phosphate to the tyrosine residues substrates. RTKs demonstrate essential roles in cellular growth, metabolism, differentiation, and motility. Anomalous expression of RTK customarily leads to cell growth dysfunction, which is connected to tumor takeover, angiogenesis, and metastasis. Understanding the structure, mechanisms of adaptive and acquired resistance, optimizing inhibition of RTKs, and eradicating cum minimizing the havocs of quiescence cancer cells is paramount.

MainText

Tyrosine kinase inhibitors (TKIs) vie with RTKs ATP-binding site for ATP and hitherto reduce tyrosine kinase phosphorylation, thus hampering the growth of cancer cells. TKIs can either be monoclonal antibodies that compete for the receptor’s extracellular domain or small molecules that inhibit the tyrosine kinase domain and prevent conformational changes that activate RTKs. Progression of cancer is related to aberrant activation of RTKs due to due to mutation, excessive expression, or autocrine stimulation.

Conclusions

Understanding the modes of inhibition and structures of RTKs is germane to the design of novel and potent TKIs. This review shed light on the structures of tyrosine kinases, receptor tyrosine kinases, tyrosine kinase inhibitors, minimizing imatinib associated toxicities, optimization of tyrosine kinase inhibition in curtailing quiescence in cancer cells and the prospects of receptor tyrosine kinase based treatments.

Serine 474 phosphorylation is essential for maximal Akt2 kinase activity in adipocytes

The Ser/Thr protein kinase Akt regulates essential biological processes such as cell survival, growth, and metabolism. Upon growth factor stimulation, Akt is phosphorylated at Ser⁴⁷⁴; however, how this phosphorylation contributes to Akt activation remains controversial. Previous studies, which induced loss of Ser⁴⁷⁴ phosphorylation by ablating its upstream kinase mTORC2, have implicated Ser⁴⁷⁴ phosphorylation as a driver of Akt substrate specificity. Here we directly studied the role of Akt2 Ser⁴⁷⁴ phosphorylation in 3T3-L1 adipocytes by preventing Ser⁴⁷⁴ phosphorylation without perturbing mTORC2 activity. This was achieved by utilizing a chemical genetics approach, where ectopically expressed S474A Akt2 was engineered with a W80A mutation to confer resistance to the Akt inhibitor MK2206, and thus allow its activation independent of endogenous Akt. We found that insulin-stimulated phosphorylation of four bona fide Akt substrates (TSC2, PRAS40, FOXO1/3a, and AS160) was reduced by ∼50% in the absence of Ser⁴⁷⁴ phosphorylation. Accordingly, insulin-stimulated mTORC1 activation, protein synthesis, FOXO nuclear exclusion, GLUT4 translocation, and glucose uptake were attenuated upon loss of Ser⁴⁷⁴ phosphorylation. We propose a model where Ser⁴⁷⁴ phosphorylation is required for maximal Akt2 kinase activity in adipocytes.

Comprehensive Study on Thiadiazole-Based Anticancer Agents Inducing Cell Cycle Arrest and Apoptosis/Necrosis Through Suppression of Akt Activity in Lung Adenocarcinoma and Glioma Cells

Objectives

Akt is considered as an attractive target for anticancer drug discovery and development and therefore extensive efforts have been devoted to the discovery of new potent anticancer agents targeting Akt.

Materials and Methods

Due to the importance of thiadiazoles for anticancer drug discovery, herein eight 1,3,4-thiadiazole derivatives were investigated for their cytotoxic effects on C6 rat glioma and A549 human lung adenocarcinoma cell lines using the MTT assay. The effects of the most promising anticancer agents on apoptosis, caspase-3 activation, mitochondrial membrane potential, and cell cycle arrest were determined on a BD FACSAria (I) flow cytometer. Akt activity was measured in the C6 and A549 cell lines using an ELISA colorimetric method. Schrödinger's Maestro molecular modeling package was used to explore the possible binding modes of compounds 3 and 8 in the active site of Akt enzyme (PDB code: 3OW4).

Results

N-(4-Chlorophenyl)-2-[(5-((4-nitrophenyl)amino)-1,3,4-thiadiazol-2-yl)thio]acetamide (3) and N-(6-nitrobenzothiazol-2-yl)-2-[(5-((4- nitrophenyl)amino)-1,3,4-thiadiazol-2-yl)thio]acetamide (8) induced apoptosis and cell cycle arrest in the C6 cell line through inhibition of Akt activity (92.36% and 86.52%, respectively). The docking results of compounds 3 and 8 indicated that π-π interactions, H bonds, and salt-bridge formation were responsible for the observed Akt inhibitory activity.

Conclusion

According to in vitro and docking studies, compounds 3 and 8 stand out as promising antiglioma agents.

Design, synthesis, in vitro and in silico evaluation of a new series of oxadiazole-based anticancer agents as potential Akt and FAK inhibitors

In the current work, new 1,3,4-oxadiazole derivatives were synthesized and investigated for their cytotoxic effects on A549 human lung adenocarcinoma, C6 rat glioma and NIH/3T3 mouse embryonic fibroblast cell lines. Compounds 2, 6 and 9 were found to be the most potent anticancer agents against A549 and C6 cell lines and therefore their effects on apoptosis, caspase-3 activation, Akt, FAK, mitochondrial membrane potential and ultrastructural morphological changes were evaluated. N-(5-Nitrothiazol-2-yl)-2-[[5-[((5,6,7,8-tetrahydronaphthalen-2-yl)oxy)methyl]-1,3,4-oxadiazol-2-yl]thio]acetamide (9) increased early and late apoptotic cell population in A549 and C6 cells more than cisplatin and caused more mitochondrial membrane depolarization in both cell lines than cisplatin. On the other hand, N-(6-methoxybenzothiazol-2-yl)-2-[[5-[((5,6,7,8-tetrahydronaphthalen-2-yl)oxy)methyl]-1,3,4-oxadiazol-2-yl]thio]acetamide (6) caused higher caspase-3 activation than cisplatin in both cell lines. Compound 6 showed significant Akt inhibitory activity in both cell lines. Moreover, compound 6 significantly inhibited FAK (Phospho-Tyr397) activity in C6 cell line. Molecular docking simulations demonstrated that compound 6 fitted into the active sites of Akt and FAK with high affinity and substrate-specific interactions. Furthermore, compounds 2, 6 and 9 caused apoptotic morphological changes in both cell lines obtained from micrographs by transmission electron microscopy. A computational study for the prediction of ADME properties of all compounds was also performed. These compounds did not violate Lipinski's rule, making them potential orally bioavailable anticancer agents.

Design, Synthesis, and Evaluation of a New Series of Thiazole-Based Anticancer Agents as Potent Akt Inhibitors

In an attempt to develop potent anticancer agents targeting Akt, new thiazole derivatives (1⁻10) were synthesized and investigated for their cytotoxic effects on A549 human lung adenocarcinoma, C6 rat glioma, and NIH/3T3 (healthy) mouse embryonic fibroblast cell lines. The most potent compounds were also investigated for their effects on apoptosis and Akt pathway. The most promising anticancer agent was found to be 2-[2-((4-(4-cyanophenoxy)phenyl)methylene)hydrazinyl]-4-(4-cyanophenyl)thiazole (6), due to its selective inhibitory effects on A549 and C6 cells with IC₅₀ values of 12.0 ± 1.73 µg/mL and 3.83 ± 0.76 µg/mL, respectively. Furthermore, compound 6 increased early and late apoptotic cell population (32.8%) in C6 cell line more than cisplatin (28.8%) and significantly inhibited the Akt enzyme. The molecular docking study was performed to predict the possible binding modes of compounds A, 6, and 8 inside the active site of Akt (PDB code: 4EJN). Molecular docking simulations were found to be in accordance with in vitro studies and, hence, supported the biological activity. A computational study for the prediction of absorption, distribution, metabolism and excretion (ADME) properties of all compounds was also performed. On the basis of Lipinski's rule of five, the compounds were expected to be potential orally bioavailable agents.

A 2D-QSAR and Grid-Independent Molecular Descriptor (GRIND) Analysis of Quinoline-Type Inhibitors of Akt2: Exploration of the Binding Mode in the Pleckstrin Homology (PH) Domain

Protein kinase B-β (PKBβ/Akt2) is a serine/threonine-specific protein kinase that has emerged as one of the most important regulators of cell growth, differentiation, and division. Upregulation of Akt2 in various human carcinomas, including ovarian, breast, and pancreatic, is a well-known tumorigenesis phenomenon. Early on, the concept of the simultaneous administration of anticancer drugs with inhibitors of Akt2 was advocated to overcome cell proliferation in the chemotherapeutic treatment of cancer. However, clinical studies have not lived up to the high expectations, and several phase II and phase III clinical studies have been terminated prematurely because of severe side effects related to the non-selective isomeric inhibition of Akt2. The notion that the sequence identity of pleckstrin homology (PH) domains within Akt-isoforms is less than 30% might indicate the possibility of the development of selective antagonists against the Akt2 PH domain. Therefore, in this study, various in silico tools were utilized to explore the hypothesis that quinoline-type inhibitors bind in the Akt2 PH domain. A Grid-Independent Molecular Descriptor (GRIND) analysis indicated that two hydrogen bond acceptors, two hydrogen bond donors and one hydrophobic feature at a certain distance from each other were important for the selective inhibition of Akt2. Our docking results delineated the importance of Lys30 as an anchor point for mapping the distances of important amino acid residues in the binding pocket, including Lys14, Glu17, Arg25, Asn53, Asn54 and Arg86. The binding regions identified complement the GRIND-based pharmacophoric features.

Akt inhibitors in cancer treatment: The long journey from drug discovery to clinical use (Review)

Targeted cancer therapies are used to inhibit the growth, progression, and metastasis of the tumor by interfering with specific molecular targets and are currently the focus of anticancer drug development. Protein kinase B, also known as Akt, plays a central role in many types of cancer and has been validated as a therapeutic target nearly two decades ago. This review summarizes the intracellular functions of Akt as a pivotal point of converging signaling pathways involved in cell growth, proliferation, apoptotis and neo‑angiogenesis, and focuses on the drug design strategies to develop potent anticancer agents targeting Akt. The discovery process of Akt inhibitors has evolved from adenosine triphosphate (ATP)‑competitive agents to alternative approaches employing allosteric sites in order to overcome the high degree of structural similarity between Akt isoforms in the catalytic domain, and considerable structural analogy to the AGC kinase family. This process has led to the discovery of inhibitors with greater specificity, reduced side-effects and lower toxicity. A second generation of Akt has inhibitors emerged by incorporating a chemically reactive Michael acceptor template to target the nucleophile cysteines in the catalytic activation loop. The review outlines the development of several promising drug candidates emphasizing the importance of each chemical scaffold. We explore the pipeline of Akt inhibitors and their preclinical and clinical examination status, presenting the potential clinical application of these agents as a monotherapy or in combination with ionizing radiation, other targeted therapies, or chemotherapy.

The critical role of Akt in cardiovascular function

Akt kinase, a member of AGC kinases, is important in many cellular functions including proliferation, migration, cell growth and metabolism. There are three known Akt isoforms which play critical and diverse roles in the cardiovascular system. Akt activity is regulated by its upstream regulatory pathways at transcriptional and post-translational levels. Beta-catenin/Tcf-4, GLI1 and Stat-3 are some of few known transcriptional regulators of AKT gene. Threonine 308 and serine 473 are the two critical phosphorylation sites of Akt1. Translocation of Akt to the cell membrane facilitates PDK1 phosphorylation of the threonine site. The serine site is phosphorylated by mTORC2. Ack1, Src, PTK6, TBK1, IKBKE and IKKε are some of the non-canonical pathways which affect the Akt activity. Protein-protein interactions of Akt to actin and Hsp90 increase the Akt activity while Akt binding to other proteins such as CTMP and TRB3 reduces the Akt activity. The action of Akt on its downstream targets determines its function in cardiovascular processes such as cell survival, growth, proliferation, angiogenesis, vasorelaxation, and cell metabolism. Akt promotes cell survival via caspase-9, YAP, Bcl-2, and Bcl-x activities. Inhibition of FoxO proteins by Akt also increases cell survival by transcriptional mechanisms. Akt stimulates cell growth and proliferation through mTORC1. Akt also increases VEGF secretion and mediates eNOS phosphorylation, vasorelaxation and angiogenesis. Akt can increase cellular metabolism through its downstream targets GSK3 and GLUT4. The alterations of Akt signaling play an important role in many cardiovascular pathological processes such as atherosclerosis, cardiac hypertrophy, and vascular remodeling. Several Akt inhibitors have been developed and tested as anti-tumor agents. They could be potential novel therapeutics for the cardiovascular diseases.

Exploitation of the ability of γ-tocopherol to facilitate membrane co-localization of Akt and PHLPP1 to develop PHLPP1-targeted Akt inhibitors

Previously, we reported that Akt inactivation by γ-tocopherol (2) in PTEN-negative prostate cancer cells resulted from its unique ability to facilitate membrane co-localization of Akt and PHLPP1 (PH domain leucine-rich repeat protein phosphatase isoform 1), a Ser473-specific Akt phosphatase, through pleckstrin homology (PH) domain binding. This finding provided a basis for exploiting 2 to develop a novel class of PHLPP1-targeted Akt inhibitors. Here, we used 3 (γ-VE5), a side chain-truncated 2 derivative, as a scaffold for lead optimization. The proof-of-concept of this structural optimization was obtained by 20, which exhibited higher antitumor efficacy than 3 in PTEN-negative cancer cells through PHLPP1-facilitated Akt inactivation. Like 3, 20 preferentially recognized the PH domains of Akt and PHLPP1, as its binding affinities for other PH domains, including those of ILK and PDK1, were an order-of-magnitude lower. Moreover, 20 was orally active in suppressing xenograft tumor growth in nude mice, which underlines the translational potential of this new class of Akt inhibitor in PTEN-deficient cancers.

Redox biology in normal cells and cancer: restoring function of the redox/Fyn/c-Cbl pathway in cancer cells offers new approaches to cancer treatment

This review discusses a unique discovery path starting with novel findings on redox regulation of precursor cell and signaling pathway function and identification of a new mechanism by which relatively small changes in redox status can control entire signaling networks that regulate self-renewal, differentiation, and survival. The pathway central to this work, the redox/Fyn/c-Cbl (RFC) pathway, converts small increases in oxidative status to pan-activation of the c-Cbl ubiquitin ligase, which controls multiple receptors and other proteins of central importance in precursor cell and cancer cell function. Integration of work on the RFC pathway with attempts to understand how treatment with systemic chemotherapy causes neurological problems led to the discovery that glioblastomas (GBMs) and basal-like breast cancers (BLBCs) inhibit c-Cbl function through altered utilization of the cytoskeletal regulators Cool-1/βpix and Cdc42, respectively. Inhibition of these proteins to restore normal c-Cbl function suppresses cancer cell division, increases sensitivity to chemotherapy, disrupts tumor-initiating cell (TIC) activity in GBMs and BLBCs, controls multiple critical TIC regulators, and also allows targeting of non-TICs. Moreover, these manipulations do not increase chemosensitivity or suppress division of nontransformed cells. Restoration of normal c-Cbl function also allows more effective harnessing of estrogen receptor-α (ERα)-independent activities of tamoxifen to activate the RFC pathway and target ERα-negative cancer cells. Our work thus provides a discovery strategy that reveals mechanisms and therapeutic targets that cannot be deduced by standard genetics analyses, which fail to reveal the metabolic information, isoform shifts, protein activation, protein complexes, and protein degradation critical to our discoveries.

Novel inhibitors induce large conformational changes of GAB1 pleckstrin homology domain and kill breast cancer cells

The Grb2-associated binding protein 1 (GAB1) integrates signals from different signaling pathways and is over-expressed in many cancers, therefore representing a new therapeutic target. In the present study, we aim to target the pleckstrin homology (PH) domain of GAB1 for cancer treatment. Using homology models we derived, high-throughput virtual screening of five million compounds resulted in five hits which exhibited strong binding affinities to GAB1 PH domain. Our prediction of ligand binding affinities is also in agreement with the experimental K_D values. Furthermore, molecular dynamics studies showed that GAB1 PH domain underwent large conformational changes upon ligand binding. Moreover, these hits inhibited the phosphorylation of GAB1 and demonstrated potent, tumor-specific cytotoxicity against MDA-MB-231 and T47D breast cancer cell lines. This effort represents the discovery of first-in-class GAB1 PH domain inhibitors with potential for targeted breast cancer therapy and provides novel insights into structure-based approaches to targeting this protein.

In this paper, we described the identification and evaluation of a set of first-in-class potent inhibitors targeting a new cancer target, Grb2-associated binder-1 (GAB1), which integrates signals from different signaling pathways, and is frequently over-expressed in cancer cells. To achieve our goals, we have employed intensive computational modeling to understand the structure of the GAB1 pleckstrin homology (PH) domain and screened five million compounds. Upon biological evaluation, we found that several inhibitors that induced large conformational changes of the target structure exhibited strong selective binding to GAB1 PH domain. Particularly, these inhibitors demonstrated potent and tumor-specific cytotoxicity in breast cancer cells. This represents a groundbreaking discovery in targeting GAB1 signaling which may be used for cancer therapy, especially for triple negative breast cancer patients.

Inhibition of phosphatidylinositol-3,4,5-trisphosphate binding to the AKT pleckstrin homology domain by 4-amino-1,2,5-oxadiazole derivatives

4-Amino-1,2,5-oxadiazole derivatives has been developed as an inhibitor of AKT pleckstrin homology domain.

Inhibition of redox/Fyn/c-Cbl pathway function by Cdc42 controls tumour initiation capacity and tamoxifen sensitivity in basal-like breast cancer cells

We found that basal-like breast cancer (BLBC) cells use Cdc42 to inhibit function of the redox/Fyn/c-Cbl (RFC) pathway, which normally functions to convert small increases in oxidative status into enhanced degradation of c-Cbl target proteins. Restoration of RFC pathway function by genetic or pharmacological Cdc42 inhibition enabled harnessing of pro-oxidant effects of low µM tamoxifen (TMX) concentrations - concentrations utilized in trials on multiple tumour types - to suppress division and induce death of BLBC cells in vitro and to confer TMX sensitivity in vivo through oestrogen receptor-α-independent mechanisms. Cdc42 knockdown also inhibited generation of mammospheres in vitro and tumours in vivo, demonstrating the additional importance of this pathway in tumour initiating cell (TIC) function. These findings provide a new regulatory pathway that is subverted in cancer cells, a novel means of attacking TIC and non-TIC aspects of BLBCs, a lead molecule (ML141) that confers sensitivity to low µM TMX in vitro and in vivo and also appear to be novel in enhancing sensitivity to a non-canonical mode of action of an established therapeutic agent.

Basis of a FTIR spectroscopy methodology for automated evaluation of Akt kinase inhibitor on leukemic cell lines used as model

The PI3K/Akt-signaling pathway, associated with cancer development and disease progression, is recognized to be an anti-tumor drug target that could present important therapeutic benefit. However, no targeted Akt medicines have been commercialized yet, reflecting that drug selection procedures requires significant improvement from early research to clinical trials. Thus, new methods permitting both the evaluation of cytotoxic and proliferation inhibition effect on cancer cells but also to provide a global fingerprint of the drug action mechanism of new Akt inhibitor candidates are of major interest. Because it can detect very subtle molecular changes and could provide a global fingerprint of drug effects on cells, Fourier-transform infrared (FTIR) spectroscopy appears to be a promising method to develop new time- and cost-saving tools for chemical library screening improvements. In this study, we combine FTIR spectroscopy, advanced chemometrics analysis and cross-validation by standard biological assays to establish a basis of a mid-throughput methodology for rapid and automated assessment of cell response to Akt inhibitors and quantitative evaluation of their anti-proliferative effects. Our results shows that our methodology is able (1) to detect cell response to an Akt inhibitor exposure even for very low doses, (2) to provide biochemical information of interest about its effects on the cell metabolism, lipidome, and proteome, (3) to predict accurately resulting cell proliferation inhibition rate. Thus, further based on a large spectral data base, our methodology could contribute to facilitate preliminary screening of chemical libraries and improving the selection procedure of drug candidates in laboratory routine.

Synthesis, cytotoxicity of new 4-arylidene curcumin analogues and their multi-functions in inhibition of both NF-κB and Akt signalling

A series of new 4-arylidene curcumin analogues (4-arylidene-1,7-bisarylhepta-1,6-diene-3,5-diones) were synthesized and found to be potent antiproliferative agents against a panel of cancer cell lines at submicromolar to low micromolar concentrations by SRB assay. Their inhibitory abilities against NF-κB was evaluated by High Content Analysis (HCA) based immunofluorescence assay; and the Akt signalling inhibition was determined by fluorescence polarization assay and western blot respectively. The Structure-Activity Relationship was discussed. Our results revealed that 4-arylidene curcumin analogues may work in a multi-targets manner in cancer cell.

Determination of SGK1 mRNA in non-small cell lung cancer samples underlines high expression in squamous cell carcinomas

Background

Lung cancer represents the most frequent cause of death for cancer. In non-small cell lung cancer (NSCLC), which accounts for the vast majority of this disease, only early detection and treatment, when possible, may significantly affect patient's prognosis. An important role in NSCLC malignancy is attributed to the signal transduction pathways involving PI3Kinase, with consequent activation of the AKT family factors. The serum and glucocorticoid kinase (SGK) factors, which share high structural and functional homologies with the AKT factors, are a family of ubiquitously expressed serine/threonine kinases under the control of cellular stress and hormones. SGK1 is the most represented SGK member.

Methods

By means of immunohistochemistry and quantitative real-time PCR, we determined SGK1 protein and mRNA expression in a cohort of 66 formalin-fixed, paraffin-embedded NSCLC surgical samples. All samples belonged to patients with a well-documented clinical history.

Results

mRNA expression was significantly higher in squamous cell carcinomas, and correlated with several clinical prognostic indicators, being elevated in high-grade tumors and in tumors with bigger size and worse clinical stage. No correlation was found between SGK1 protein expression and these clinical parameters.

Conclusions

This explorative analysis of SGK1 expression in NSCLC samples highlights the potential role of this factor in NSCLC patients' prognosis. Moreover, the higher expression in the squamous cell carcinoma subtype opens new therapeutic possibilities in this NSCLC subtype by designing specific kinase inhibitors.

Accurate prediction of the bound form of the Akt pleckstrin homology domain using normal mode analysis to explore structural flexibility

Molecular docking is often performed with rigid receptors. This can be a serious limitation, since the receptor often differs between bound and unbound forms or between bound forms with different ligands. We recently developed a normal-mode based docking method and showed that it is possible to obtain reasonable estimates of the complexed form of the pleckstrin homology (PH) domain of Akt, starting with the free form of the receptor. With inositol (1,3,4,5)-tetrakisphosphate (IP4) as the ligand the docked results agree with the known high-resolution X-ray crystal structure of the IP4-Akt PH domain complex. We also tested our methods with PH4, SC66, and PIT-1, several recently designed PH domain inhibitors. The results are shown to be consistent with available experimental data and previous modeling studies. The method we described can be used for molecular docking analysis even when only an approximation of the experimental structure or model is known.