Preclinical pharmacology, antitumor activity, and development of pharmacodynamic markers for the novel, potent AKT inhibitor CCT128930

Large-scale characterization of drug mechanism of action using proteome-wide thermal shift assays

In response to an ever-increasing demand of new small molecules therapeutics, numerous chemical and genetic tools have been developed to interrogate compound mechanism of action. Owing to its ability to characterize compound-dependent changes in thermal stability, the proteome-wide thermal shift assay has emerged as a powerful tool in this arsenal. The most recent iterations have drastically improved the overall efficiency of these assays, providing an opportunity to screen compounds at a previously unprecedented rate. Taking advantage of this advance, we quantified 1.498 million thermal stability measurements in response to multiple classes of therapeutic and tool compounds (96 compounds in living cells and 70 compounds in lysates). When interrogating the dataset as a whole, approximately 80% of compounds (with quantifiable targets) caused a significant change in the thermal stability of an annotated target. There was also a wealth of evidence portending off-target engagement despite the extensive use of the compounds in the laboratory and/or clinic. Finally, the combined application of cell- and lysate-based assays, aided in the classification of primary (direct ligand binding) and secondary (indirect) changes in thermal stability. Overall, this study highlights the value of these assays in the drug development process by affording an unbiased and reliable assessment of compound mechanism of action.

AKT2 inhibition accelerates the acquisition of phagocytic ability in induced pluripotent stem cell-derived neutrophils

Neutrophils are key components of the immune system that inhibit bacterial infections. Systemic bacterial infections can cause lethal conditions, especially in patients with neutropenia associated with chemotherapy or other systemic illnesses; hence, early detection of the symptoms and prompt management are crucial in such cases. Previously, we established expandable engineered neutrophil-primed progenitors (NeuPs-XL) using human-induced pluripotent stem cells (iPSCs), which can produce neutrophil-like cells at a clinically suitable scale within 4 days of inducing myeloid differentiation. In this study, using small-molecule compound-based screening, we detected that MK-2206, a selective pan-AKT inhibitor, can accelerate this differentiation process, promote phagocytic ability in neutrophils, and enhance cytokine and chemokine expression in response to lipopolysaccharides. The inhibition of AKT2 has been identified as the key mechanism underlying this acceleration. These results can make a substantial contribution to the development of strategies for the prompt production of clinically applicable iPSC-derived neutrophils, which can potentially lead to the management of severe infections associated with life-threatening neutropenia and the effective treatment of related health conditions in the future.

Trailblazers in cancer research: the next generation - the British Association of Cancer Research early-career conference

The inaugural 'British Association of Cancer Research (BACR) Early Career Conference, Trailblazers in Cancer Research 2023', was a 2-day meeting held in Manchester, UK. Recognising the disruption caused by the COVID-19 pandemic to early-career researchers (ECRs), the BACR executive committee organised an in-person conference to address the lack of network and training opportunities during this time. The conference brought together PhD students and post-doctoral researchers from across the UK and beyond, who shared their outstanding contributions to cancer research. The meeting incorporated several cutting-edge cancer themes, including 'Cancer Cell Signalling and The Tumour Microenvironment'; 'Emerging Approaches in Cancer Treatment'; 'Cancer Omics and Lifestyle', and 'Nutrition and Cancer'. Alongside showcasing world-class cancer research, the meeting included a career-focused session which allowed industrial and non-academic speakers to provide vital insight into alternative career paths aside from the familiar 'academic' route. Importantly, the conference also introduced delegates to Patient Public Involvement in cancer research, an area of limited experience for many. Overall, the BACR Trailblazers Conference was hugely successful and presented an excellent platform for collaboration and networking among ECRs in cancer research.

CRISPR-Cas9 identifies growth-related subtypes of glioblastoma with therapeutical significance through cell line knockdown

BACKGROUND

Glioblastoma (GBM) is a type of highly malignant brain tumor that is known for its significant intratumoral heterogeneity, meaning that there can be a high degree of variability within the tumor tissue. Despite the identification of several subtypes of GBM in recent years, there remains to explore a classification based on genes related to proliferation and growth.

METHODS

The growth-related genes of GBM were identified by CRISPR-Cas9 and univariate Cox regression analysis. The expression of these genes in the Cancer Genome Atlas cohort (TCGA) was used to construct growth-related genes subtypes (GGSs) via consensus clustering. Validation of this subtyping was performed using the nearest template prediction (NTP) algorithm in two independent Gene Expression Omnibus (GEO) cohorts and the ZZ cohort. Additionally, copy number variations, biological functions, and potential drugs were analyzed for each of the different subtypes separately.

RESULTS

Our research established multicenter-validated GGSs. GGS1 exhibits the poorest prognosis, with the highest frequency of chr 7 gain & chr 10 loss, and the lowest frequency of chr 19 & 20 co-gain. Additionally, GGS1 displays the highest expression of EGFR. Furthermore, it is significantly enriched in metabolic, stemness, proliferation, and signaling pathways. Besides we showed that Foretinib may be a potential therapeutic agent for GGS1, the worst prognostic subtype, through data screening and in vitro experiments. GGS2 has a moderate prognosis, with a slightly higher proportion of chr 7 gain & chr 10 loss, and the highest proportion of chr 19 & 20 co-gain. The prognosis of GGS3 is the best, with the least chr 7 gain & 10 loss and EGFR expression.

CONCLUSIONS

These results enhance our understanding of the heterogeneity of GBM and offer insights for stratified management and precise treatment of GBM patients.

Recent advances in PI3K/PKB/mTOR inhibitors as new anticancer agents

The biochemical role of the PI3K/PKB/mTOR signalling pathway in cell-cycle regulation is now well known. During the onset and development of different forms of cancer it becomes overactive reducing apoptosis and allowing cell proliferation. Therefore, this pathway has become an important target for the treatment of various forms of malignant tumors, including breast cancer and follicular lymphoma. Recently, several more or less selective inhibitors targeting these proteins have been identified. In general, drugs that act on multiple targets within the entire pathway are more efficient than single targeting inhibitors. Multiple inhibitors exhibit high potency and limited drug resistance, resulting in promising anticancer agents. In this context, the present survey focuses on small molecule drugs capable of modulating the PI3K/PKB/mTOR signalling pathway, thus representing drugs or drug candidates to be used in the pharmacological treatment of different forms of cancer.

AKT2 reduces IFNβ1 production to modulate antiviral responses and systemic lupus erythematosus

Interferon regulatory factor 3 (IRF3)-induced type I interferon (I-IFN) production plays key roles in both antiviral and autoimmune responses. IRF3 phosphorylation, dimerization, and nuclear localization are needed for its activation and function, but the precise regulatory mechanisms remain to be explored. Here, we show that the serine/threonine kinase AKT2 interacts with IRF3 and phosphorylates it on Thr207, thereby attenuating IRF3 nuclear translocation in a 14-3-3ε-dependent manner and reducing I-IFN production. We further find that AKT2 expression is downregulated in viral-infected macrophages or in monocytes and tissue samples from systemic lupus erythematosus (SLE) patients and mouse models. Akt2-deficient mice exhibit increased I-IFN induction and reduced mortality in response to viral infection, but aggravated severity of SLE. Overexpression of AKT2 kinase-inactive or IRF3-T207A mutants in zebrafish supports that AKT2 negatively regulates I-IFN production and antiviral response in a kinase-dependent manner. This negative role of AKT2 in IRF3-induced I-IFN production suggests that AKT2 may be therapeutically targeted to differentially regulate antiviral infection and SLE.

AKT Isoforms as a Target in Cancer and Immunotherapy

Over the past years, targeted therapies have received tremendous attention in cancer therapy. One of the most frequently targeted pathways is the PI3K/AKT/mTOR signaling pathway that regulates crucial cellular processes including proliferation, survival, and migration. In a wide variety of cancer entities, the PI3K/AKT/mTOR signaling pathway was found to be a critical driver of disease progression, indicating a noteworthy target in cancer therapy. This chapter focuses on targeted therapies against AKT, which is a key enzyme within the PI3K/AKT/mTOR pathway. Although the three different isoforms of AKT, namely AKT1, AKT2, and AKT3, have a high homology, the isoforms exhibit different biological functions. Recently, direct inhibitors against all AKT isoforms as well as selective inhibitors against specific AKT isoforms have been extensively investigated in preclinical work as well as in clinical trials to attenuate proliferation of cancer cells. While no AKT inhibitor has been approved by the FDA for cancer therapy to date, AKT still plays a crucial role in a variety of treatment strategies including immune checkpoint inhibition. In this chapter, we summarize the status of AKT inhibitors either targeting all or specific AKT isoforms. Furthermore, we explain the role of AKT signaling in direct inhibition of tumor cell growth as well as in immune cells and immune checkpoint inhibition.

Nanoprotein Interaction Atlas Reveals the Transport Pathway of Gold Nanoparticles across Epithelium and Its Association with Wnt/β-Catenin Signaling

A tremendous number of proteins participate in the delivery and transport process of nanomedicines. Nanoprotein interactions not only mediate drug delivery but also determine drug safety. In the field of biomedical sciences, the epithelial barrier is a huge challenge for gastrointestinal, intratracheal, intranasal, vaginal, and intrauterine delivery of nanomedicines. However, the molecular mechanisms by which nanomedicines cross tissue or cell barriers are not well understood. Here, we explored the nanoprotein interactions during the transcytosis of nanoparticles across the epithelial barrier by focusing on the transport pathway and mechanisms. Due to the limitations of traditional methods in resolving nanoprotein interactions, we developed a backward analysis strategy. By simultaneously analyzing the protein corona on the particle surface and the cellular response after transcytosis, we integrated the information on both directly and indirectly interacting proteins, establishing a holistic nanoprotein interaction atlas. It revealed the dominant role of the EV/ER/Golgi/SV pathway in the transcytosis of nanoparticles. More importantly, based on the established atlas, we discovered the association of Wnt/β-catenin signaling with nanoparticle transportation. The endocytosis for entering cells and exocytosis/transcytosis for leaving cells were differently regulated by the Wnt pathway. Notably, this regulatory effect was dependent on the particle size. Bigger nanoparticles departed from cells through the exocytosis pathway faster because of the specific bridging effect on the Wnt-Frizzled interaction and the feedback loop construction based on the exosomes. This mechanism gives an interpretation at the molecular level to the transcytosis dilemma of larger nanoparticles. Moreover, the size-dependent Wnt/β-catenin signaling pathway provides a promising regulatory and screening platform for the transportation of different nanomedicines through the epithelial barrier.

Modular Photocatalytic Synthesis of α-Trialkyl-α-Tertiary Amines

Molecules displaying an α-trialkyl-α-tertiary amine motif provide access to an important and versatile area of biologically relevant chemical space but are challenging to access through existing synthetic methods. Here, we report an operationally straightforward, multicomponent protocol for the synthesis of a range of functionally and structurally diverse α-trialkyl-α-tertiary amines, which makes use of three readily available components: dialkyl ketones, benzylamines, and alkenes. The strategy relies on the of use visible-light-mediated photocatalysis with readily available Ir(III) complexes to bring about single-electron reduction of an all-alkyl ketimine species to an α-amino radical intermediate; the α-amino radical undergoes Giese-type addition with a variety of alkenes to forge the α-trialkyl-α-tertiary amine center. The mechanism of this process is believed to proceed through an overall redox neutral pathway that involves photocatalytic redox-relay of the imine, generated from the starting amine-ketone condensation, through to an imine-derived product. This is possible because the presence of a benzylic amine component in the intermediate scaffold drives a 1,5-hydrogen atom transfer step after the Giese addition to form a stable benzylic α-amino radical, which is able to close the photocatalytic cycle. These studies detail the evolution of the reaction platform, an extensive investigation of the substrate scope, and preliminary investigation of some of the mechanistic features of this distinct photocatalytic process. We believe this transformation will provide convenient access to previously unexplored α-trialkyl-α-tertiary amine scaffolds that should be of considerable interest to practitioners of synthetic and medicinal chemistry in academic and industrial institutions.

Akt isoforms differentially provide for chemoresistance in prostate cancer

OBJECTIVE

Early prostate cancer micrometastatic foci undergo a mesenchymal to epithelial reverting transition, not only aiding seeding and colonization, but also rendering the tumor cells generally chemoresistant. We previously found that upregulated E-cadherin in the epithelial micrometastases activated canonical survival pathways, including PI3K-Akt, that protected the tumor cells from death; however, the extent of protection from blocking the pathway in its entirety was modest, because different isoforms may have alternately affected cell functioning. Here, we characterized Akt isoform expressions in primary and metastatic prostate cancers, as well as their individual contributions to chemoresistance.

METHODS

Akt isoforms and E-cadherin were manipulated with drugs, knocked down, and over expressed. Tumor cell killing was determined in vitro and in vivo. Overall survival was calculated from patient records and specimens.

RESULTS

Pan-Akt inhibition sensitized tumor cells to chemotherapy, and specific blockade of Akt1 or/and Akt2 caused cells to be more chemoresponsive. Overexpression of Akt3 induced apoptosis. A low dose of Akt1 or Akt2 inhibitor enabled standard chemotherapies to significantly eradicate metastatic prostate tumors in a mouse model, acting as chemosensitizers. In human specimens, we found Akt1 and Akt2 positively correlated, whereas Akt3 inversely correlated, with the overall survival of prostate cancer patients. Akt1high/Akt2high/Akt3low tumors had the worst outcomes.

CONCLUSIONS

E-cadherin-induced activation of Akt1/2 isoforms was the essential mechanism of chemoresistance, whereas Akt3 made cells more fragile. These findings emphasized the need to target Akt1/2, rather than pan-Akt, as a rational therapeutic approach.

Biological Role of AKT and Regulation of AKT Signaling Pathway by Thymoquinone: Perspectives in Cancer Therapeutics

BACKGROUND

AKT/PKB is an important enzyme with numerous biological functions, and its overexpression is related to carcinogenesis. AKT stimulates different signaling pathways that are downstream of activated tyrosine kinases and phosphatidylinositol 3-kinase, hence functions as an important target for anti-cancer drugs.

OBJECTIVE

In this review article, we have interpreted the role of AKT signaling pathway in cancer and the natural inhibitory effect of Thymoquinone (TQ) in AKT and its possible mechanisms.

METHOD

We have collected the updated information and data on AKT, its role in cancer and the inhibitory effect of TQ in AKT signaling pathway from Google Scholar, PubMed, Web of Science, Elsevier, Scopus, and many more.

RESULTS

Many drugs are already developed, which can target AKT, but very few among them have passed clinical trials. TQ is a natural compound, mainly found in black cumin, which has been found to have potential anti-cancer activities. TQ targets numerous signaling pathways, including AKT, in different cancers. In fact, many studies revealed that AKT is one of the major targets of TQ. The preclinical success of TQ suggests its clinical studies on cancer.

CONCLUSION

This review article summarizes the role of AKT in carcinogenesis, its potent inhibitors in clinical trials, and how TQ acts as an inhibitor of AKT and TQ's future as a cancer therapeutic drug.

Immunohistological Examination of AKT Isoforms in the Brain: Cell-Type Specificity That May Underlie AKT's Role in Complex Brain Disorders and Neurological Disease

Protein kinase B (PKB/AKT) is a central kinase involved in many neurobiological processes. AKT is expressed in the brain as three isoforms, AKT1, AKT2, and AKT3. Previous studies suggest isoform-specific roles in neural function, but very few studies have examined AKT isoform expression at the cellular level. In this study, we use a combination of histology, immunostaining, and genetics to characterize cell-type-specific expression of AKT isoforms in human and mouse brains. In mice, we find that AKT1 is the most broadly expressed isoform, with expression in excitatory neurons and the sole detectable AKT isoform in gamma-aminobutyric acid ergic interneurons and microglia. By contrast, we find that AKT2 is the sole isoform expressed in astroglia and is not detected in other neural cell types. We find that AKT3 is expressed in excitatory neurons with AKT1 but shows greater expression levels in dendritic compartments than AKT1. We extend our analysis to human brain tissues and find similar results. Using genetic deletion approaches, we also find that the cellular determinants restricting AKT isoform expression to specific cell types remain intact under Akt deficiency conditions. Because AKT signaling is linked to numerous neurological disorders, a greater understanding of cell-specific isoform expression could improve treatment strategies involving AKT.

CCT128930 is a novel and potent antagonist of TRPM7 channel

Transient receptor potential melastatin 7 (TRPM7) channels represent a major magnesium (Mg²⁺)-uptake component in mammalian cells and are negatively modulated by internal Mg²⁺. However, few TRPM7 modulators were identified so far, which hindered the understanding of the TRPM7 channel functions. In this study, we identified that CCT128930, an ATP-competitive protein kinase B inhibitor reported previously, was a potent TRPM7 channel antagonist. The inhibition of CCT128930 on TRPM7 was independent of intracellular Mg²⁺. In the absence and presence of 300 μM Mg²⁺ in pipette solution, the IC₅₀ values were 0.86 ± 0.11 μM and 0.63 ± 0.09 μM, respectively. Subtype selectivity data showed that CCT128930 preferentially inhibited TRPM7 channels compared to TRPM6 and TRPM8 isoforms. In addition, CCT128930 was found to be able to reduce the endogenous TRPM7-like currents in SH-SY5Y neuroblastoma cells. At last, multiple residues in the superficial part of the TRPM7 selectivity filter were identified to be critical for the inhibitory activity of CCT128930 which are different from the determinants of Mg²⁺ and reported TRPM7 antagonists. Our results indicated that CCT128930 is a novel and potent TRPM7 channel antagonist.

Somatic Copy Number Alterations and Associated Genes in Clear-Cell Renal-Cell Carcinoma in Brazilian Patients

Somatic copy number aberrations (CNAs) have been associated with clear-cell renal carcinoma (ccRCC) pathogenesis and are a potential source of new diagnostic, prognostic and therapeutic biomarkers. Recurrent CNAs include loss of chromosome arms 3p, 14q, 9p, and gains of 5q and 8q. Some of these regional CNAs are suspected of altering gene expression and could influence clinical outcomes. Despite many studies of CNAs in RCC, there are currently no descriptions of genomic copy number alterations in a Brazilian ccRCC cohort. This study was designed to evaluate the chromosomal profile of CNAs in Brazilian ccRCC tumors and explore clinical associations. A total of 92 ccRCC Brazilian patients that underwent nephrectomy at Barretos Cancer Hospital were analyzed for CNAs by array comparative genomic hybridization. Most patients in the cohort had early-stage localized disease. The most significant alterations were loss of 3p (87.3%), 14q (35.8%), 6q (29.3%), 9p (28.6%) and 10q (25.0%), and gains of 5q (59.7%), 7p (29.3%) and 16q (20.6%). Bioinformatics analysis revealed 19 genes mapping to CNA significant regions, including SETD2, BAP1, FLT4, PTEN, FGFR4 and NSD1. Moreover, gain of 5q34-q35.3 (FLT4 and NSD1) and loss of 6q23.2-q23.3 (MYB) and 9p21.3 (MLLT3) had gene expression levels that correlated with TCGA data and was also associated with advanced disease features, such as larger tumors, Fuhrman 3, metastasis at diagnosis and death. The loss of region 14q22.1 which encompasses the NIN gene was associated with poor overall survival. Overall, this study provides the first CNA landscape of Brazilian patients and pinpoints genomic regions and specific genes worthy of more detailed investigations. Our results highlight important genes that are associated with copy number changes involving large chromosomal regions that are potentially related to ccRCC tumorigenesis and disease biology for future clinical investigations.

Novel pyrrolopyrimidine derivatives induce p53-independent apoptosis via the mitochondrial pathway in colon cancer cells

A series of novel pyrrolopyrimidine urea derivatives were synthesized and evaluated for their anticancer activity against colon cancer cell lines. Compounds showed the remarkable cytotoxic activity on HCT-116 wt cell line. The most potent compound 4c (IC₅₀ = 0.14 μM) induced apoptosis in HCT-116 wt and HCT-116 p53-/- cell lines. Otherwise, treatment of HCT-116 BAX-/-BAK-/- cells with compound 4c didn't lead to activation of apoptosis, suggesting that compound 4c induces apoptotic cell death by activating BAX/BAK-dependent pathway. Moreover, while the compound 4c increase the activation of caspase-3 and caspase-9 levels in HCT-116 wt and HCT-116 p53-/- cells, caspase-3 or caspase-9 activation was not observed in HCT-116 BAX-/-BAK-/- cells. In addition, compound 4c induced mitochondrial apoptosis in cells grown as oncospheroids, which better mimic the in vivo milieu of tumors. 4c treatment also activated JNK along with inhibition of prosurvival kinases such as Akt and ERK 1/2 in HCT-116 wt and HCT-116 p53 -/- cells as well as in HCT-116 BAX-/-BAK-/- cells. Notably, our results indicated that compound 4c induced mitochondrial apoptosis through activation p53-independent apoptotic signaling pathways.

Light-emitting diode irradiation induces AKT/mTOR-mediated apoptosis in human pancreatic cancer cells and xenograft mouse model

The beneficial effects of light-emitting diode (LED) irradiation have been reported in various pathologies, including cancer. However, its effect in pancreatic cancer cells remains unclear. Herein, we demonstrated that blue LED of 460 nm regulated pancreatic cancer cell proliferation and apoptosis by suppressing the expression of apoptosis-related factors, such as mutant p53 and B-cell lymphoma 2 (Bcl-2), and decreasing the expression of RAC-β serine/threonine kinase 2 (AKT2), the phosphorylation of protein kinase B (AKT), and mammalian target of rapamycin (mTOR). Blue LED irradiation also increased the levels of cleaved poly-(ADP-ribose) polymerase (PARP) and caspase-3 in pancreatic cancer cells, while it suppressed AKT2 expression and inhibited tumor growth in xenograft tumor tissues. In conclusion, blue LED irradiation suppressed pancreatic cancer cell and tumor growth by regulating AKT/mTOR signaling. Our findings indicated that blue LEDs could be used as a nonpharmacological treatment for pancreatic cancer.

Targeting telomerase for its advent in cancer therapeutics

Telomerase has emerged as an important primary target in anticancer therapy. It is a distinctive reverse transcriptase enzyme, which extends the length of telomere at the 3' chromosomal end, and uses telomerase reverse transcriptase (TERT) and telomerase RNA template-containing domains. Telomerase has a vital role and is a contributing factor in human health, mainly affecting cell aging and cell proliferation. Due to its unique feature, it ensures unrestricted cell proliferation in malignancy and plays a major role in cancer disease. The development of telomerase inhibitors with increased specificity and better pharmacokinetics is being considered to design and develop newer potent anticancer agents. Use of natural and synthetic compounds for the inhibition of telomerase activity can lead to an opening of new vistas in cancer treatment. This review details about the telomerase biochemistry, use of natural and synthetic compounds; vaccines and oncolytic virus in therapy that suppress the telomerase activity. We have discussed structure-activity relationships of various natural and synthetic telomerase inhibitors to help medicinal chemists and chemical biology researchers with a ready reference and updated status of their clinical trials. Suppression of human TERT (hTERT) activity through inhibition of hTERT promoter is an important approach for telomerase inhibition.

A comprehensive review in improving delivery of small-molecule chemotherapeutic agents overcoming the blood-brain/brain tumor barriers for glioblastoma treatment

Glioblastoma (GBM) is the most common and lethal primary brain tumor which is highly resistant to conventional radiotherapy and chemotherapy, and cannot be effectively controlled by surgical resection. Due to inevitable recurrence of GBM, it remains essentially incurable with a median overall survival of less than 18 months after diagnosis. A great challenge in current therapies lies in the abrogated delivery of most of the chemotherapeutic agents to the tumor location in the presence of blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). These protective barriers serve as a selectively permeable hurdle reducing the efficacy of anti-tumor drugs in GBM therapy. This work systematically gives a comprehensive review on: (i) the characteristics of the BBB and the BBTB, (ii) the influence of BBB/BBTB on drug delivery and the screening strategy of small-molecule chemotherapeutic agents with promising BBB/BBTB-permeable potential, (iii) the strategies to overcome the BBB/BBTB as well as the techniques which can lead to transient BBB/BBTB opening or disruption allowing for improving BBB/BBTB-penetration of drugs. It is hoped that this review provide practical guidance for the future development of small BBB/BBTB-permeable agents against GBM as well as approaches enhancing drug delivery across the BBB/BBTB to GBM.

Idelalisib inhibits vitreous-induced Akt activation and proliferation of retinal pigment epithelial cells from epiretinal membranes

Proliferative vitreoretinopathy (PVR) is a blinding fibrotic eye disease that develops in 8-10% of patients who undergo primary retinal detachment-reparative surgery and in 40-60% of patients with open-globe injury. At present, there is no pharmacological treatment for this devastating disease. Vitreal growth factors activate their respective receptors of cells in the vitreous, trigger their downstream signaling transduction (e.g. phosphoinositide 3 kinases (PI3Ks)/Akt), and drive cellular responses intrinsic to the pathogenesis of PVR. PI3Ks play a central role in experimental PVR. However, which isoform(s) are involved in PVR pathogenesis remain unknown. Herein, we show that p110δ, a catalytic subunit of receptor-regulated PI3K isoform δ, is highly expressed in epiretinal membranes from patients with PVR, and that idelalisib, a specific inhibitor of PI3Kδ, effectively inhibits vitreous-induced Akt activation, proliferation, migration and contraction of retinal pigment epithelial cells derived from an epiretinal membrane of a PVR patient. Small molecules of kinase inhibitors have shown great promise as a class of therapeutics for a variety of human diseases. The data herein suggest that idelalisib is a promising PVR prophylactic.

Akt1 and Akt2 Isoforms Play Distinct Roles in Regulating the Development of Inflammation and Fibrosis Associated with Alcoholic Liver Disease

Akt kinase isoforms (Akt1, Akt2, and Akt3) have generally been thought to play overlapping roles in phosphoinositide 3-kinase (PI3K)-mediated-signaling. However, recent studies have suggested that they display isoform-specific roles in muscle and fat. To determine whether such isoform-specificity is observed with respect to alcoholic liver disease (ALD) progression, we examined the role of Akt1, Akt2, and Akt3 in hepatic inflammation, and pro-fibrogenic proliferation and migration using Kupffer cells, hepatic stellate cells (HSC), and hepatocytes in an ethanol and lipopolysaccharide (LPS)-induced two-hit model in vitro and in vivo. We determined that siRNA-directed silencing of Akt2, but not Akt1, significantly suppressed cell inflammatory markers in HSC and Kupffer cells. Although both Akt1 and Akt2 inhibited cell proliferation in HSC, only Akt2 inhibited cell migration. Both Akt1 and Akt2, but not Akt3, inhibited fibrogenesis in hepatocytes and HSC. In addition, our in vivo results show that administration of chronic ethanol, binge ethanol and LPS (EBL) in wild-type C57BL/6 mice activated all three Akt isoforms with concomitant increases in activated forms of phosphoinositide dependent kinase-1 (PDK1), mammalian target-of-rapamycin complex 2 (mTORC2), and PI3K, resulting in upregulation in expression of inflammatory, proliferative, and fibrogenic genes. Moreover, pharmacological blocking of Akt2, but not Akt1, inhibited EBL-induced inflammation while blocking of both Akt1 and Akt2 inhibited pro-fibrogenic marker expression and progression of fibrosis. Our findings indicate that Akt isoforms play unique roles in inflammation, cell proliferation, migration, and fibrogenesis during EBL-induced liver injury. Thus, close attention must be paid when targeting all Akt isoforms as a therapeutic intervention.

The anti-inflammatory agent bindarit acts as a modulator of fatty acid-binding protein 4 in human monocytic cells

We investigated the cellular and molecular mechanisms by which bindarit, a small indazolic derivative with prominent anti-inflammatory effects, exerts its immunoregulatory activity in lipopolysaccharide (LPS) stimulated human monocytic cells. We found that bindarit differentially regulates the release of interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1), enhancing the release of IL-8 and reducing that of MCP-1. These effects specifically required a functional interaction between bindarit and fatty acid binding protein 4 (FABP4), a lipid chaperone that couples intracellular lipid mediators to their biological targets and signaling pathways. We further demonstrated that bindarit can directly interact with FABP4 by increasing its expression and nuclear localization, thus impacting on peroxisome proliferator-activated receptor γ (PPARγ) and LPS-dependent kinase signaling. Taken together, these findings suggest a potential key-role of FABP4 in the immunomodulatory activity of bindarit, and extend the spectrum of its possible therapeutic applications to FABP4 modulation.

Neutrophils homing into the retina trigger pathology in early age-related macular degeneration

Age-related macular degeneration (AMD) is an expanding problem as longevity increases worldwide. While inflammation clearly contributes to vision loss in AMD, the mechanism remains controversial. Here we show that neutrophils are important in this inflammatory process. In the retinas of both early AMD patients and in a mouse model with an early AMD-like phenotype, we show neutrophil infiltration. Such infiltration was confirmed experimentally using ribbon-scanning confocal microscopy (RSCM) and IFNλ- activated dye labeled normal neutrophils. With neutrophils lacking lipocalin-2 (LCN-2), infiltration was greatly reduced. Further, increased levels of IFNλ in early AMD trigger neutrophil activation and LCN-2 upregulation. LCN-2 promotes inflammation by modulating integrin β1 levels to stimulate adhesion and transmigration of activated neutrophils into the retina. We show that in the mouse model, inhibiting AKT2 neutralizes IFNλ inflammatory signals, reduces LCN-2-mediated neutrophil infiltration, and reverses early AMD-like phenotype changes. Thus, AKT2 inhibitors may have therapeutic potential in early, dry AMD.

Inhibitors of AKT kinase increase LDL receptor mRNA expression by two different mechanisms

Protein kinase B (AKT) is a serine/threonine kinase that functions as an important downstream effector of phosphoinositide 3-kinase. We have recently shown that MK-2206 and triciribine, two highly selective AKT inhibitors increase the level of low density lipoprotein receptor (LDLR) mRNA which leads to increased amount of cell-surface LDLRs. However, whereas MK-2206 induces transcription of the LDLR gene, triciribine stabilizes LDLR mRNA, raising the possibility that the two inhibitors may actually affect other kinases than AKT. In this study, we aimed to ascertain the role of AKT in regulation of LDLR mRNA expression by examining the effect of five additional AKT inhibitors on LDLR mRNA levels. Here we show that in cultured HepG2 cells, AKT inhibitors ARQ-092, AKT inhibitor VIII, perifosine, AT7867 and CCT128930 increase LDLR mRNA levels by inducing the activity of LDLR promoter. CCT128930 also increased the stability of LDLR mRNA. To study the role of AKT isoforms on LDLR mRNA levels, we examined the effect of siRNA-mediated knockdown of AKT1 or AKT2 on LDLR promoter activity and LDLR mRNA stability. Whereas knockdown of either AKT1 or AKT2 led to upregulation of LDLR promoter activity, only knockdown of AKT2 had a stabilizing effect on LDLR mRNA. Taken together, these results provide strong evidence for involvement of AKT in regulation of LDLR mRNA expression, and point towards the AKT isoform specificity for upregulation of LDLR mRNA expression.

AKT as a Therapeutic Target for Cancer

Many cellular processes in cancer are attributed to kinase signaling networks. V-akt murine thymoma viral oncogene homolog (AKT) plays a major role in the PI3K/AKT signaling pathways. AKT is activated by PI3K or phosphoinositide-dependent kinases (PDK) as well as growth factors, inflammation, and DNA damage. Signal transduction occurs through downstream effectors such as mTOR, glycogen synthase kinase 3 beta (GSK3β), or forkhead box protein O1 (FOXO1). The abnormal overexpression or activation of AKT has been observed in many cancers, including ovarian, lung, and pancreatic cancers, and is associated with increased cancer cell proliferation and survival. Therefore, targeting AKT could provide an important approach for cancer prevention and therapy. In this review, we discuss the rationale for targeting AKT and also provide details regarding synthetic and natural AKT-targeting compounds and their associated studies.

Recent advances in the discovery of small molecules targeting glioblastoma

Glioblastoma (GBM) is one of the most common central nervous system cancers. It is characterized as a fast-growing tumor that arises from multiple cell types with neural stem-cell-like properties. Additionally, GBM tumors are highly invasive, which is attributed to the presence of glioblastoma stem cells that makes surgery ineffective in most cases. Currently, temozolomide is the unique chemotherapy option approved by the U.S. Food and Drug Administration for GBM treatment. This review analyzes the emergence and development of new synthetic small molecules discovered as promising anti-glioblastoma agents. A number of compounds were described herein and grouped according to the main chemical class used in the drug discovery process. Importantly, we focused only on synthetic compounds published in the last 10 years, thus excluding natural products. Furthermore, we included in this review only those most biologically active compounds with proven in vitro and/or in vivo efficacy.

In Vitro and In Vivo Antitumor and Anti-Inflammatory Capabilities of the Novel GSK3 and CDK9 Inhibitor ABC1183

Glycogen synthase kinase-3s (GSK3α and GSK3β) are constitutively active protein kinases that target over 100 substrates, incorporate into numerous protein complexes, and regulate such vital cellular functions as proliferation, apoptosis, and inflammation. Cyclin-dependent kinase 9 (CDK9) regulates RNA production as a component of positive transcription elongation factor b and promotes expression of oncogenic and inflammatory genes. Simultaneous inhibition of these signaling nodes is a promising approach for drug discovery, although previous compounds exhibit limited selectivity and clinical efficacy. The novel diaminothiazole ABC1183 is a selective GSK3α/β and CDK9 inhibitor and is growth-inhibitory against a broad panel of cancer cell lines. ABC1183 treatment decreases cell survival through G2/M arrest and modulates oncogenic signaling through changes in GSK3, glycogen synthase, and β-catenin phosphorylation and MCL1 expression. Oral administration, which demonstrates no organ or hematologic toxicity, suppresses tumor growth and inflammation-driven gastrointestinal disease symptoms, owing in part to downregulation of tumor necrosis factor α and interleukin-6 proinflammatory cytokines. Therefore, ABC1183 is strategically poised to effectively mitigate multiple clinically relevant diseases.

Protein kinase B: emerging mechanisms of isoform-specific regulation of cellular signaling in cancer

The serine/threonine protein kinase B (PKB), also known as Akt, is one of the multifaceted kinases in the human kinome, existing in three isoforms. PKB plays a vital role in phosphoinositide 3-kinase (PI3K)-mediated oncogenesis in various malignancies and is one of the attractive targets for cancer drug discovery. Recent studies have shown that the functional significance of an individual isoform of PKB is not redundant in cancer. It has been found that PKB isoforms play distinct roles in the regulation of cellular invasion and migration during tumorigenesis. PKB activation plays a central role during epithelial-mesenchymal transition, a cellular program required for the cancer cell invasion and migration. However, the differential behavior of each PKB isoform has been shown in the regulation of epithelial-mesenchymal transition. Recent studies have suggested that PKBα (Akt1) plays a conflicting role in tumorigenesis by acting either as a pro-oncogenic factor by suppressing the apoptotic machinery or by restricting tumor invasion. PKBβ (Akt2) promotes cell migration and invasion and similarly PKBγ (Akt3) has been reported to promote tumor migration. As PKB is known for its pro-oncogenic properties, it needs to be unraveled how three isoforms of PKB compensate during tumor progression. In this review, we attempted to sum up how different isoforms of PKB play a role in cancer progression, metastasis, and drug resistance.

Lack of Constitutively Active DNA Repair Sensitizes Glioblastomas to Akt Inhibition and Induces Synthetic Lethality with Radiation Treatment in a p53-Dependent Manner

Treatment refractory glioblastoma (GBM) remains a major clinical problem globally, and targeted therapies in GBM have not been promising to date. The Cancer Genome Atlas integrative analysis of GBM reported the striking finding of genetic alterations in the p53 and PI3K pathways in more than 80% of GBMs. Given the role of these pathways in making cell-fate decisions and responding to genotoxic stress, we investigated the reliance of these two pathways in mediating radiation resistance. We selected a panel of GBM cell lines and glioma stem cells (GSC) with wild-type TP53 (p53-wt) and mutant TP53, mutations known to interfere with p53 functionality (p53-mt). Cell lines were treated with a brain permeable inhibitor of P-Akt (ser473), phosphatidylinositol ether lipid analogue (PIA), with and without radiation treatment. Sensitivity to treatment was measured using Annexin-V/PI flow cytometry and Western blot analysis for the markers of apoptotic signaling, alkaline COMET assay. All results were verified in p53 isogenic cell lines. p53-mt cell lines were selectively radiosensitized by PIA. This radiosensitization effect corresponded with an increase in DNA damage and a decrease in DNA-PKcs levels. TP53 silencing in p53-wt cells showed a similar response as the p53-mt cells. In addition, the radiosensitization effects of Akt inhibition were not observed in normal human astrocytes, suggesting that this treatment strategy could have limited off-target effects. We demonstrate that the inhibition of the PI3K/Akt pathway by PIA radiosensitizes p53-mt cells by antagonizing DNA repair. In principle, this strategy could provide a large therapeutic window for the treatment of TP53-mutant tumors. Mol Cancer Ther; 17(2); 336-46. ©2017 AACRSee all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology."

PRAS40 signaling in tumor

The proline-rich Akt substrate of 40 kDa (PRAS40) is a substrate of Akt and a component of the mammalian target of rapamycin complex 1 (mTORC1). Locating at the crossroad of the PI3K/Akt pathway and the mTOR pathway, PRAS40 is phosphorylated by growth factors or other stimuli, and regulates the activation of these signaling pathways in turn. PRAS40 plays an important role in metabolic disorders and multiple cancers, and the phosphorylation of PRAS40 is often associated with the tumor progression of melanoma, prostate cancer, etc. PRAS40 promotes tumorigenesis by deregulating cellular proliferation, apoptosis, senescence, metastasis, etc. Herein, we provide an overview on current understandings of PRAS40 signaling in the tumor formation and progression, which suggests that PRAS40 or phospho-PRAS40 could become a novel biomarker and therapeutic target in tumor.

AKT1 and AKT2 isoforms play distinct roles during breast cancer progression through the regulation of specific downstream proteins

The purpose of this study was to elucidate the mechanisms associated with the specific effects of AKT1 and AKT2 isoforms in breast cancer progression. We modulated the abundance of specific AKT isoforms in IBH-6 and T47D human breast cancer cell lines and showed that AKT1 promoted cell proliferation, through S6 and cyclin D1 upregulation, but it inhibited cell migration and invasion through β1-integrin and focal adhesion kinase (FAK) downregulation. In contrast, AKT2 promoted cell migration and invasion through F-actin and vimentin induction. Thus, while overexpression of AKT1 promoted local tumor growth, downregulation of AKT1 or overexpression of AKT2 promoted peritumoral invasion and lung metastasis. Furthermore, we evaluated The Cancer Genome Atlas (TCGA) dataset for invasive breast carcinomas and found that increased AKT2 but not AKT1 mRNA levels correlated with a worse clinical outcome. We conclude that AKT isoforms play specific roles in different steps of breast cancer progression, with AKT1 involved in the local tumor growth and AKT2 involved in the distant tumor dissemination, having AKT2 a poorer prognostic value and consequently being a worthwhile target for therapy.

Identification of new pyrrolo[2,3-d]pyrimidines as Src tyrosine kinase inhibitors in vitro active against Glioblastoma

In the last few years, several pyrrolo-pyrimidine derivatives have been either approved by the US FDA and in other countries for the treatment of different diseases or are currently in phase I/II clinical trials. Herein we present the synthesis and the characterization of a novel series of pyrrolo[2,3-d]pyrimidines, compounds 8a-j, and their activity against Glioblastoma multiforme (GBM). Docking studies and MM-GBSA analysis revealed the ability of such compounds to efficiently interact with the ATP binding site of Src. Enzymatic assays against a mini-panel of kinases (Src, Fyn, EGFR, Kit, Flt3, Abl, AblT315I) have been performed, showing an unexpected selectivity of our pyrrolo[2,3-d]pyrimidines for Src. Finally, the derivatives were tested for their antiproliferative potency on U87 GBM cell line. Compound 8h showed a considerable cytotoxicity effect against U87 cell line with an IC₅₀ value of 7.1 μM.

Using high-throughput sequencing transcriptome data for INDEL detection: challenges for cancer drug discovery

INTRODUCTION

A cancer cell is a mosaic of genomic and epigenomic alterations. Distinct cancer molecular signatures can be observed depending on tumor type or patient genetic background. One type of genomic alteration is the insertion and/or deletion (INDEL) of nucleotides in the DNA sequence, which may vary in length, and may change the encoded protein or modify protein domains. INDELs are associated to a large number of diseases and their detection is done based on low-throughput techniques. However, high-throughput sequencing has also started to be used for detection of novel disease-causing INDELs. This search may identify novel drug targets.

AREAS COVERED

This review presents examples of using high-throughput sequencing (DNA-Seq and RNA-Seq) to investigate the incidence of INDELs in coding regions of human genes. Some of these examples successfully utilized RNA-Seq to identify INDELs associated to diseases. In addition, other studies have described small INDELs related to chemo-resistance or poor outcome of patients, while structural variants were associated with a better clinical outcome.

EXPERT OPINION

On average, there is twice as much RNA-Seq data available at the most used repositories for such data compared to DNA-Seq. Therefore, using RNA-Seq data is a promising strategy for studying cancer samples with unknown mechanisms of drug resistance, aiming at the discovery of proteins with potential as novel drug targets.

A Switch in Akt Isoforms Is Required for Notch-Induced Snail1 Expression and Protection from Cell Death

Notch activation in aortic endothelial cells (ECs) takes place at embryonic stages during cardiac valve formation and induces endothelial-to-mesenchymal transition (EndMT). Using aortic ECs, we show here that active Notch expression promotes EndMT, resulting in downregulation of vascular endothelial cadherin (VE-cadherin) and upregulation of mesenchymal genes such as those for fibronectin and Snail1/2. In these cells, transforming growth factor β1 exacerbates Notch effects by increasing Snail1 and fibronectin activation. When Notch-downstream pathways were analyzed, we detected an increase in glycogen synthase kinase 3β (GSK-3β) phosphorylation and inactivation that facilitates Snail1 nuclear retention and protein stabilization. However, the total activity of Akt was downregulated. The discrepancy between Akt activity and GSK-3β phosphorylation is explained by a Notch-induced switch in the Akt isoforms, whereby Akt1, the predominant isoform expressed in ECs, is decreased and Akt2 transcription is upregulated. Mechanistically, Akt2 induction requires the stimulation of the β-catenin/TCF4 transcriptional complex, which activates the Akt2 promoter. Active, phosphorylated Akt2 translocates to the nucleus in Notch-expressing cells, resulting in GSK-3β inactivation in this compartment. Akt2, but not Akt1, colocalizes in the nucleus with lamin B in the nuclear envelope. In addition to promoting GSK-3β inactivation, Notch downregulates Forkhead box O1 (FoxO1), another Akt2 nuclear substrate. Moreover, Notch protects ECs from oxidative stress-induced apoptosis through an Akt2- and Snail1-dependent mechanism.

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.

Implications of Akt2/Twist crosstalk on breast cancer metastatic outcome

Akt2 is a pivotal player in a complex web of signaling pathways controlling cell growth, proliferation, and survival. The deregulation or aberrations of Akt2 have been associated with tumor progression, metastatic spread, and, lastly, chemoresistance. The impairment of its activity has gained more attention because Akt2 is intertwined with a range of signaling paths, including the Phosphatidylinositol 3 kinase/Akt/Mammalian target of rapamycin (PI3K/mTOR) signaling axis, which are involved in macromolecules synthesis and metabolism. Here, we focus on Akt2 because of its involvement in the acquisition of stem cell-like properties, responsible for invasiveness and chemoresistance, also promoted by Twist. We also suggest therapeutic strategies targeting Akt2 to overcome the drawbacks of current cancer therapies.

Human platelet lysate improves human cord blood derived ECFC survival and vasculogenesis in three dimensional (3D) collagen matrices

Human cord blood (CB) is enriched in circulating endothelial colony forming cells (ECFCs) that display high proliferative potential and in vivo vessel forming ability. Since diminished ECFC survival is known to dampen the vasculogenic response in vivo, we tested how long implanted ECFC survive and generate vessels in three-dimensional (3D) type I collagen matrices in vitro and in vivo. We hypothesized that human platelet lysate (HPL) would promote cell survival and enhance vasculogenesis in the 3D collagen matrices. We report that the percentage of ECFC co-cultured with HPL that were alive was significantly enhanced on days 1 and 3 post-matrix formation, compared to ECFC alone containing matrices. Also, co-culture of ECFC with HPL displayed significantly more vasculogenic activity compared to ECFC alone and expressed significantly more pro-survival molecules (pAkt, p-Bad and Bcl-xL) in the 3D collagen matrices in vitro. Treatment with Akt1 inhibitor (A-674563), Akt2 inhibitor (CCT128930) and Bcl-xL inhibitor (ABT-263/Navitoclax) significantly decreased the cell survival and vasculogenesis of ECFC co-cultured with or without HPL and implicated activation of the Akt1 pathway as the critical mediator of the HPL effect on ECFC in vitro. A significantly greater average vessel number and total vascular area of human CD31(+) vessels were present in implants containing ECFC and HPL, compared to the ECFC alone implants in vivo. We conclude that implantation of ECFC with HPL in vivo promotes vasculogenesis and augments blood vessel formation via diminishing apoptosis of the implanted ECFC.

A first-in-human phase I trial of LY2780301, a dual p70 S6 kinase and Akt Inhibitor, in patients with advanced or metastatic cancer

The primary objective of this phase I study of LY2780301, a dual p70 S6 kinase and Akt inhibitor, was to determine the recommended phase II dose as a single agent in patients with advanced cancer. Secondary objectives included safety, pharmacokinetic, and pharmacodynamic analyses, and co-clinical analyses in Avatar models. Eligible patients received total daily doses of LY2780301 100-500 mg, given orally as a single dose or divided into 2 doses for 28-day cycles. Dose escalation followed 3 + 3 design. The primary pharmacodynamic endpoint was inhibition of S6 assessed by skin and tumor biopsy. Thirty-two patients were treated. Common toxicities possibly related to treatment included constipation (19 %), fatigue (13 %), nausea (9 %), and diarrhea (9 %). Grade 3/4 toxicities potentially related to treatment were anemia (n = 2), increased alanine aminotransferase/aspartate aminotransferase (ALT) (n = 1), and increased gamma-glutamyl transpeptidase (GGT) (n = 1). One patient experienced best overall response of prolonged stable disease for 6 cycles. Plasma exposures of LY2780301 exceeded predicted efficacious exposures, but were not dose proportional. Among patients receiving 500 mg daily >50 % exhibited reduced S6 in skin biopsies at Day 8 of treatment, but the effect was not maintained. Plasma concentrations of LY2780301 and/or its metabolites were not correlated with S6 expression in the epidermis. There was minimal antitumor activity against the model, CRC 019. Avatar models showed minimal pharmacodynamic effects consistent with the observed antitumor effects. This study suggests a dose of LY2780301 500 mg QD for future studies.

Effects of an oral allosteric AKT inhibitor (MK-2206) on human nasopharyngeal cancer in vitro and in vivo

Aim

Protein kinase B (AKT) signaling frequently is deregulated in human cancers and plays an important role in nasopharyngeal carcinoma (NPC). This preclinical study investigated the effect of MK-2206, a potent allosteric AKT inhibitor, on human NPC cells in vitro and in vivo.

Methods

The effect of MK-2206 on the growth and proliferation of CNE-1, CNE-2, HONE-1, and SUNE-1 cells was assessed by Cell Counting Kit 8 and colony formation assay. Flow cytometry was performed to analyze cell cycle and apoptosis. The effects of MK-2206 on the AKT pathway were analyzed by Western blotting. Autophagy induction was evaluated via electron microscopy and Western blot. To test the effects of MK-2206 in vivo, CNE-2 cells were subcutaneously implanted into nude mice. Tumor-bearing mice were treated orally with MK-2206 or placebo. Tumors were harvested for immunohistochemical analysis.

Results

In vitro, MK-2206 inhibited the four NPC cell line growths and reduced the sizes of the colonies in a dose-dependent manner. At 72 and 96 hours, the half maximal inhibitory concentration (IC₅₀) values of MK-2206 in CNE-1, CNE-2, and HONE-1 cell lines were 3–5 μM, whereas in SUNE-1, IC₅₀ was less than 1 μM, and MK-2206 induced cell cycle arrest at the G1 phase. However, our study found no evidence of apoptosis. MK-2206 induced autophagy in NPC cells, as evidenced by electron microscopy and Western blot, and inhibited the growth of tumors that were subcutaneously implanted in mice. Inhibition of downstream phosphorylation through the PRAS40 and S6 pathways seems to be the main mechanism for the MK-2206-induced growth inhibition.

Conclusion

Our preclinical study suggests that MK-2206’s antiproliferative effect may be useful for NPC treatment; however, strategies for reinforcing this effect are needed to maximize clinical benefit.

CCT128930 induces cell cycle arrest, DNA damage, and autophagy independent of Akt inhibition

PI3K/Akt/mTOR pathway plays an important role in tumor progression and anti-cancer drug resistance. The aim of the present study is to determine the antitumor effect of CCT128930, a novel small molecule inhibitor of Akt, in the HepG2 hepatoma cancer cells. Our results showed that at low concentrations, CCT128930 increased, but not inhibited, the phosphorylation of Akt in HepG2 and A549 cells. CCT128930 inhibited cell proliferation by inducing cell cycle arrest in G1 phase through downregulation of cyclinD1 and Cdc25A, and upregulation of p21, p27 and p53. A higher dose (20 μM) of CCT128930 triggered cell apoptosis with activation of caspase-3, caspase-9, and PARP. Treatment with CCT128930 increased phosphorylation of ERK and JNK in HepG2 cells. CCT128930 activated DNA damage response of HepG2 cell characterized by phosphorylation of H2AX, ATM (ataxia-telangiectasia mutated), Chk1 and Chk2. Upon exposure to CCT128930 at a higher concentration, HepG2 cells exhibited autophagy was accompanied by an increase the levels of LC3-II and Beclin-1. Blocking autophagy using chloroquine magnified CCT128930-induced apoptotic cell death and the phosphorylation of H2AX. The results in this study have advanced our current understandings of the anti-cancer mechanisms of CCT128930 in cancer cells.

Nuclear PRAS40 couples the Akt/mTORC1 signaling axis to the RPL11-HDM2-p53 nucleolar stress response pathway

The Ribosomal Protein (RP)-HDM2-p53 pathway has been shown to play key roles in oncogene-induced apoptosis and senescence, but the mechanism regulating this pathway remains elusive. The Proline-Rich Akt Substrate of 40 kDA (PRAS40) has recently been identified as a binding partner and inhibitor of the mechanistic Target of Rapamycin Complex 1 (mTORC1). Although other inhibitors of mTORC1 are known tumor suppressors, PRAS40 promotes cell survival and tumorigenesis. Here we demonstrate that Akt- and mTORC1-mediated phosphorylation of PRAS40 at T246 and S221, respectively, promotes nuclear-specific association of PRAS40 with Ribosomal Protein L11 (RPL11). Importantly, silencing of PRAS40 induces upregulation of p53 in a manner dependent upon RPL11. This effect is rescued by wild type PRAS40, but not by the RPL11 binding-null PRAS40 T246A mutant. We find that PRAS40 negatively regulates the RPL11-HDM2-p53 nucleolar stress response pathway and suppresses induction of p53-mediated cellular senescence. This work identifies nuclear PRAS40 as a dual-input signaling checkpoint that links cell growth and proliferation to inhibition of cellular senescence. These findings may help to explain the pro-tumorigenic effect of PRAS40 and identify the PRAS40-RPL11 complex as a promising target for p53-restorative anti-cancer drug discovery.

Akt inhibitors: mechanism of action and implications for anticancer therapeutics

Akt, better known as protein kinase B (PKB), is a serine/threonine-specific protein kinase which acts as mediator via PI3K/Akt pathway in many biological processes like glucose metabolism, apoptosis, cell differentiation and transcription. Akt1 gene amplification has been implicated in gastric carcinoma while Akt2 amplification has been linked with ovarian, pancreas, breast and stomach tumors. The use of Akt inhibitors as monotherapy or in combination with other anticancer drugs could be useful for combating drug resistance and improving response. Thus, comprehensive understanding of Akt and its linked signaling pathways (PI3K, PKB, mTOR etc.) is necessary to lead to newer drug development and use.

Systematic Analysis Reveals Elongation Factor 2 and α-Enolase as Novel Interaction Partners of AKT2

AKT2 is one of the three isoforms of the protein kinase AKT being involved in the modulation of cellular metabolism. Since protein-protein interactions are one possibility to convey specificity in signal transduction, we performed AKT2-protein interaction analysis to elucidate their relevance for AKT2-dependent cellular functions. We identified heat shock protein 90 kDa (HSP90), Cdc37, heat shock protein 70 kDa (HSP70), 78 kDa glucose regulated protein (GRP78), tubulin, GAPDH, α-enolase and elongation factor 2 (EF2) as AKT2-interacting proteins by a combination of tandem affinity purification and mass spectrometry in HEK293T cells. Quantitative MS-analysis using stable isotope labeling by amino acids in cell culture (SILAC) revealed that only HSP90 and Cdc37 interact stably with AKT2, whereas the other proteins interact with low affinity with AKT2. The interactions of AKT2 with α-enolase and EF2 were further analyzed in order to uncover the functional relevance of these newly discovered binding partners. Despite the interaction of AKT2 and α-enolase, which was additionally validated by proximity ligation assay (PLA), no significant impact of AKT on α-enolase activity was detected in activity measurements. AKT stimulation via insulin and/or inhibition with the ATP-competitive inhibitor CCT128930 did not alter enzymatic activity of α-enolase. Interestingly, the direct interaction of AKT2 and EF2 was found to be dynamically regulated in embryonic rat cardiomyocytes. Treatment with the PI3-kinase inhibitor LY294002 before stimulation with several hormones stabilized the complex, whereas stimulation alone led to complex dissociation which was analyzed in situ with PLA. Taken together, these findings point to new aspects of AKT2-mediated signal transduction in protein synthesis and glucose metabolism.

Use of PD biomarkers to drive dose selection and early clinical decision making

A major challenge facing the development of new therapies is the high level of compound attrition in late-stage clinical studies. A key factor in reducing these unsustainable levels of attrition is the successful evaluation of the level of drug effect on its target pathway in early development, otherwise known as testing the compound mechanism. Incorporation of PD biomarkers into Phase I/II trials to demonstrate compound binding to its molecular target and the subsequent modulation of downstream pathways enables early testing of compound mechanism and provides a data-driven framework for decisions on compound progression. This review will discuss the identification and validation of such 'fit-for-purpose' PD biomarkers, and case studies illustrating their use and value in dose selection and accelerating the clinical development of small-molecule drugs will be described.

A guide to picking the most selective kinase inhibitor tool compounds for pharmacological validation of drug targets

To establish the druggability of a target, genetic validation needs to be supplemented with pharmacological validation. Pharmacological studies, especially in the kinase field, are hampered by the fact that many reference inhibitors are not fully selective for one target. Fortunately, the initial trickle of selective inhibitors released in the public domain has steadily swelled into a stream. However, rationally picking the most selective tool compound out of the increasing amounts of available inhibitors has become progressively difficult due to the lack of accurate quantitative descriptors of drug selectivity. A recently published approach, termed 'selectivity entropy', is an improved way of expressing selectivity as a single-value parameter and enables rank ordering of inhibitors. We provide a guide to select the best tool compounds for pharmacological validation experiments of candidate drug targets using selectivity entropy. In addition, we recommend which inhibitors to use for studying the biology of the 20 most investigated kinases that are clinically relevant: Abl (ABL1), AKT1, ALK, Aurora A/B, CDKs, MET, CSF1R (FMS), EGFR, FLT3, ERBB2 (HER2), IKBKB (IKK2), JAK2/3, JNK1/2/3 (MAPK8/9/10), MEK1/2, PLK1, PI3Ks, p38α (MAPK14), BRAF, SRC and VEGFR2 (KDR).