Novel Phosphoinositide 3-Kinase/mTOR Dual Inhibitor, NVP-BGT226, Displays Potent Growth-Inhibitory Activity against Human Head and Neck Cancer Cells In Vitro and In Vivo

In vivo antitumor activity of PHT-427 inhibitor-loaded polymeric nanoparticles in head and neck squamous cell carcinoma

Recent studies on head and neck squamous cell carcinoma (HNSCC) tumorigenesis have revealed several dysregulated molecular pathways. The phosphatidylinositol-3-kinase (PI3K) signaling pathway is frequently activated in HNSCC, making it an attractive target for therapies. PHT-427 is a dual inhibitor of PI3K and the mammalian target of AKT/PDK1. This study evaluates the anticancer efficacy of the inhibitor PHT-427 loaded into polymeric nanoparticles (NP) based on α-TOS (NP-427) administered by intratumoral injection into a hypopharyngeal squamous cell carcinoma (FaDu cells) heterotopic xenograft mouse model. The nanocarrier system, based on block copolymers of N-vinylpyrrolidone (VP) and a methacrylic derivative of α-TOS (MTOS), was synthesized, and PHT-427 was loaded into the delivery system. First, we evaluated the effect of NP-427 on tumor growth by measuring tumor volume, mouse weight, survival, and the development of tumor ulceration and necrosis. In addition, we measured PI3KCA/AKT/PDK1 gene expression, PI3KCA/AKT/PDK1 protein levels, Epidermal Growth Factor Receptor (EGFR), and angiogenesis in the tumor tissue. PHT-427 encapsulation increased drug efficacy and safety, as demonstrated by decreased tumor volume, reduced PI3K/AKT/PDK1 pathway expression, and improved antitumor activity and necrosis induction in the mouse xenograft model. EGFR and angiogenesis marker (Factor VIII) expression were significantly lower in the NP-427 group compared to other experimental groups. Administration of encapsulated PHT-427 at the tumor sites proves promising for HNSCC therapy.

The molecular genetics of PI3K/PTEN/AKT/mTOR pathway in the malformations of cortical development

Malformations of cortical development (MCD) are a group of developmental disorders characterized by abnormal cortical structures caused by genetic or harmful environmental factors. Many kinds of MCD are caused by genetic variation. MCD is the common cause of intellectual disability and intractable epilepsy. With rapid advances in imaging and sequencing technologies, the diagnostic rate of MCD has been increasing, and many potential genes causing MCD have been successively identified. However, the high genetic heterogeneity of MCD makes it challenging to understand the molecular pathogenesis of MCD and to identify effective targeted drugs. Thus, in this review, we outline important events of cortical development. Then we illustrate the progress of molecular genetic studies about MCD focusing on the PI3K/PTEN/AKT/mTOR pathway. Finally, we briefly discuss the diagnostic methods, disease models, and therapeutic strategies for MCD. The information will facilitate further research on MCD. Understanding the role of the PI3K/PTEN/AKT/mTOR pathway in MCD could lead to a novel strategy for treating MCD-related diseases.

APLF facilitates interstrand DNA crosslink repair and replication fork protection to confer cisplatin resistance

Replication stress converts the stalled forks into reversed forks, which is an important protection mechanism to prevent fork degradation and collapse into poisonous DNA double-strand breaks (DSBs). Paradoxically, the mechanism also acts in cancer cells to contribute to chemoresistance against various DNA-damaging agents. PARP1 binds to and is activated by stalled forks to facilitate fork reversal. Aprataxin and polynucleotide kinase/phosphatase-like factor (APLF) binds to PARP1 through the poly(ADP-ribose) zinc finger (PBZ) domain and is known to be involved in non-homologous end joining (NHEJ). Here, we identify a novel function of APLF involved in interstrand DNA crosslink (ICL) repair and fork protection. We demonstrate that PARP1 activity facilitates the APLF recruitment to stalled forks, enabling the FANCD2 recruitment to stalled forks. The depletion of APLF sensitizes cells to cisplatin, impairs ICL repair, reduces the FANCD2 recruitment to stalled forks, and results in nascent DNA degradation by MRE11 nucleases. Additionally, cisplatin-resistant cancer cells show high levels of APLF and homologous recombination-related gene expression. The depletion of APLF sensitizes cells to cisplatin and results in fork instability. Our results reveal the novel function of APLF to facilitate ICL repair and fork protection, thereby contributing to cisplatin-resistant phenotypes of cancer cells.

Enhancing drug and cell line representations via contrastive learning for improved anti-cancer drug prioritization

Due to cancer's complex nature and variable response to therapy, precision oncology informed by omics sequence analysis has become the current standard of care. However, the amount of data produced for each patient makes it difficult to quickly identify the best treatment regimen. Moreover, limited data availability has hindered computational methods' abilities to learn patterns associated with effective drug-cell line pairs. In this work, we propose the use of contrastive learning to improve learned drug and cell line representations by preserving relationship structures associated with drug mechanisms of action and cell line cancer types. In addition to achieving enhanced performance relative to a state-of-the-art method, we find that classifiers using our learned representations exhibit a more balanced reliance on drug- and cell line-derived features when making predictions. This facilitates more personalized drug prioritizations that are informed by signals related to drug resistance.

Targeting the PI3K/AKT signaling pathway in anticancer research: a recent update on inhibitor design and clinical trials (2020-2023)

INTRODUCTION

Recent years have witnessed great achievements in drug design and development targeting the phosphatidylinositol 3-kinase/protein kinase-B (PI3K/AKT) signaling pathway, a pathway central to cell growth and proliferation. The nearest neighbor protein-protein interaction networks for PI3K and AKT show the interplays between these target proteins which can be harnessed for drug discovery. In this review, we discuss the drug design and clinical development of inhibitors of PI3K/AKT in the past three years. We review in detail the structures, selectivity, efficacy, and combination therapy of 35 inhibitors targeting these proteins, classified based on the target proteins. Approaches to overcoming drug resistance and to minimizing toxicities are discussed. Future research directions for developing combinational therapy and PROTACs of PI3K and AKT inhibitors are also discussed.

AREA COVERED

This review covers clinical trial reports and patent literature on inhibitors of PI3K and AKT published between 2020 and 2023.

EXPERT OPINION

To address drug resistance and drug toxicity of inhibitors of PI3K and AKT, it is highly desirable to design and develop subtype-selective PI3K inhibitors or subtype-selective AKT1 inhibitors to minimize toxicity or to develop allosteric drugs that can form covalent bonds. The development of PROTACs of PI3Kα or AKT helps to reduce off-target toxicities.

Advancements in dual-target inhibitors of PI3K for tumor therapy: Clinical progress, development strategies, prospects

Phosphoinositide 3-kinases (PI3Ks) modify lipids by the phosphorylation of inositol phospholipids at the 3'-OH position, thereby participating in signal transduction and exerting effects on various physiological processes such as cell growth, metabolism, and organism development. PI3K activation also drives cancer cell growth, survival, and metabolism, with genetic dysregulation of this pathway observed in diverse human cancers. Therefore, this target is considered a promising potential therapeutic target for various types of cancer. Currently, several selective PI3K inhibitors and one dual-target PI3K inhibitor have been approved and launched on the market. However, the majority of these inhibitors have faced revocation or voluntary withdrawal of indications due to concerns regarding their adverse effects. This article provides a comprehensive review of the structure and biological functions, and clinical status of PI3K inhibitors, with a specific emphasis on the development strategies and structure-activity relationships of dual-target PI3K inhibitors. The findings offer valuable insights and future directions for the development of highly promising dual-target drugs targeting PI3K.

RNA-binding protein-regulated fibronectin is essential for EGFR-activated metastasis of head and neck squamous cell carcinoma

There is a higher expression level of epidermal growth factor receptor (EGFR) in up to 90% of advanced head and neck squamous cell carcinoma (HNSCC) tissue than in normal surrounding tissues. However, the role of RNA-binding proteins (RBPs) in EGFR-associated metastasis of HNSCC remains unclear. In this study, we reveal that RBPs, specifically nucleolin (NCL) and heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1), correlated with the mesenchymal phenotype of HNSCC. The depletion of RBPs significantly attenuated EGF-induced HNSCC metastasis. Intriguingly, the EGF-induced EMT markers, such as fibronectin, were regulated by RBPs through the ERK and NF-κB pathway, followed by the enhancement of mRNA stability of fibronectin through the 5' untranslated region (5'-UTR) of the gene. The upregulation of fibronectin triggered the integrin signaling activation to enhance tumor cells' attachment to endothelial cells and increase endothelial permeability. In addition, the concurrence of EGFR and RBPs or EGFR and fibronectin was associated with overall survival and disease-free survival of HNSCC. The in vivo study showed that depletion of NCL, hnRNPA2B1, and fibronectin significantly inhibited EGF-promoted extravasation of tumor cells into lung tissues. The depletion of fibronectin or treatment with integrin inhibitors dramatically attenuated EGF-induced HNSCC metastatic nodules in the lung. Our data suggest that the RBPs/fibronectin axis is essential for EGF-induced tumor-endothelial cell interactions to enhance HNSCC cell metastasis.

The regulation of PTEN: Novel insights into functions as cancer biomarkers and therapeutic targets

This review summarizes the implications of the primary tumor suppressor protein phosphatase and tensin homolog (PTEN) in aggressive cancer development. PTEN interacts with other cellular proteins or factors suggesting the existence of an intricate molecular network that regulates their oncogenic function. Accumulating evidence has shown that PTEN exists and plays a role in the cytoplasmic organelles and in the nucleus. PTEN blocks phosphoinositide 3-kinases (PI3K)-protein kinase B-mammalian target of rapamycin signaling pathway by dephosphorylating phosphatidylinositol (PI)-3,4,5-triphosphate to PI-4,5-bisphosphate thus counteracting PI3K function. Studies have shown that PTEN expression is tightly regulated at transcriptional, posttranscriptional, and posttranslational levels (including protein-protein interactions and posttranslational modifications). Despite recent advances in PTEN research, the regulation and function of the PTEN gene remain largely unknown. How mutation or loss of specific exons in the PTEN gene occurs and involves in cancer development is not clear. This review illustrates the regulatory mechanisms of PTEN expression and discusses how PTEN participates in tumor development and/or suppression. Future prospects for the clinical applications are also highlighted.

Single-cell and spatial transcriptomics reveal 5-methylcytosine RNA methylation regulators immunologically reprograms tumor microenvironment characterizations, immunotherapy response and precision treatment of clear cell renal cell carcinoma

Clear cell Renal Cell Carcinoma (ccRCC) is a highly heterogeneous disease, making it challenging to predict prognosis and therapy efficacy. In this study, we aimed to explore the role of 5-methylcytosine (m5C) RNA modification in ccRCC and its potential as a predictor for therapy response and overall survival (OS). We established a novel 5-methylcytosine RNA modification-related gene index (M5CRMRGI) and studied its effect on the tumor microenvironment (TME) using single-cell sequencing data for in-depth analysis, and verified it using spatial sequencing data. Our results showed that M5CRMRGI is an independent predictor of OS in multiple datasets and exhibited outstanding performance in predicting the OS of ccRCC. Distinct mutation profiles, hallmark pathways, and infiltration of immune cells in TME were observed between high- and low-M5CRMRGI groups. Single-cell/spatial transcriptomics revealed that M5CRMRGI could reprogram the distribution of tumor-infiltrating immune cells. Moreover, significant differences in tumor immunogenicity and tumor immune dysfunction and exclusion (TIDE) were observed between the two risk groups, suggesting a better response to immune checkpoint blockade therapy of the high-risk group. We also predicted six potential drugs binding to the core target of the M5CRMRGI signature via molecular docking. Real-world treatment cohort data proved once again that high-risk patients were appropriate for immune checkpoint blockade therapy, while low-risk patients were appropriate for Everolimus. Our study shows that the m5C modification landscape plays a role in TME distribution. The proposed M5CRMRGI-guided strategy for predicting survival and immunotherapy efficacy, we reported here, might also be applied to more cancers other than ccRCC.

Targeted therapy for head and neck cancer: signaling pathways and clinical studies

Head and neck cancer (HNC) is malignant, genetically complex and difficult to treat and is the sixth most frequent cancer, with tobacco, alcohol and human papillomavirus being major risk factors. Based on epigenetic data, HNC is remarkably heterogeneous, and treatment remains challenging. There is a lack of significant improvement in survival and quality of life in patients with HNC. Over half of HNC patients experience locoregional recurrence or distal metastasis despite the current multiple traditional therapeutic strategies and immunotherapy. In addition, resistance to chemotherapy, radiotherapy and some targeted therapies is common. Therefore, it is urgent to explore more effective and tolerable targeted therapies to improve the clinical outcomes of HNC patients. Recent targeted therapy studies have focused on identifying promising biomarkers and developing more effective targeted therapies. A well understanding of the pathogenesis of HNC contributes to learning more about its inner association, which provides novel insight into the development of small molecule inhibitors. In this review, we summarized the vital signaling pathways and discussed the current potential therapeutic targets against critical molecules in HNC, as well as presenting preclinical animal models and ongoing or completed clinical studies about targeted therapy, which may contribute to a more favorable prognosis of HNC. Targeted therapy in combination with other therapies and its limitations were also discussed.

Discovery of 2-Methyl-2-(4-(2-methyl-8-(1H-pyrrolo[2,3-b]pyridin-6-yl)-1H-naphtho[1,2-d]imidazol-1-yl)phenyl)propanenitrile as a Novel PI3K/mTOR Inhibitor with Enhanced Antitumor Efficacy In Vitro and In Vivo

PI3K/Akt/mTOR signaling pathway is a validated drug target for cancer treatment that plays a critical role in controlling tumor growth, proliferation, and apoptosis. However, no FDA-approved PI3K/mTOR dual inhibitor exists. Thus, a candidate with a better curative effect and lower toxicity is still urgently needed. Herein, we design, synthesize, and evaluate compounds belonging to a novel series of 2-methyl-1H-imidazo[4,5-c]quinoline scaffold derivatives as PI3K/mTOR dual inhibitors. Among them, compound 8o was identified as a novel candidate with excellent kinase selectivity. It manifested remarkable antiproliferative activities against SW620 and HeLa cells. Western blot and immunohistochemical analysis results proved that 8o could regulate the PI3K/AKT/mTOR signaling pathway by inhibiting the phosphorylation of AKT and S6 proteins. Additionally, 8o presented a favorable pharmacokinetic property (oral bioavailability of 76.8%) and significant antitumor efficacy in vivo without obvious toxicity. Collectively, these results indicated that 8o is a promising agent for cancer treatment and merits further development.

A High-Throughput Screening Platform Identifies Novel Combination Treatments for Malignant Peripheral Nerve Sheath Tumors

Malignant peripheral nerve sheath tumors (MPNST) are soft-tissue sarcomas that are the leading cause of mortality in patients with Neurofibromatosis type 1 (NF1). Single chemotherapeutic agents have shown response rates ranging from 18% to 44% in clinical trials, so there is still a high medical need to identify chemotherapeutic combination treatments that improve clinical prognosis and outcome. We screened a collection of compounds from the NCATS Mechanism Interrogation PlatE (MIPE) library in three MPNST cell lines, using cell viability and apoptosis assays. We then tested whether compounds that were active as single agents were synergistic when screened as pairwise combinations. Synergistic combinations in vitro were further evaluated in patient-derived orthotopic xenograft/orthoxenograft (PDOX) athymic models engrafted with primary MPNST matching with their paired primary-derived cell line where synergism was observed. The high-throughput screening identified 21 synergistic combinations, from which four exhibited potent synergies in a broad panel of MPNST cell lines. One of the combinations, MK-1775 with Doxorubicin, significantly reduced tumor growth in a sporadic PDOX model (MPNST-SP-01; sevenfold) and in an NF1-PDOX model (MPNST-NF1-09; fourfold) and presented greater effects in TP53 mutated MPNST cell lines. The other three combinations, all involving Panobinostat (combined with NVP-BGT226, Torin 2, or Carfilzomib), did not reduce the tumor volume in vivo at noncytotoxic doses. Our results support the utility of our screening platform of in vitro and in vivo models to explore new therapeutic approaches for MPNSTs and identified that combination MK-1775 with Doxorubicin could be a good pharmacologic option for the treatment of these tumors.

A prognostic model for cervical cancer based on ferroptosis-related genes

BACKGROUND

Ferroptosis is widely involved in the occurrence and development of various cancers, but a specific mechanism involving ferroptosis in cervical cancer is still unclear.

METHODS

Based on the expressions of ferroptosis-related genes, a prognostic model was constructed using lasso regression, and the overall predictive performance of this model was verified. An in-depth analysis of the prognostic model was then conducted.

RESULTS

The prognostic model showed good predictive performance in both the validation and test sets. Mechanism analysis indicated that differences in the tumor microenvironment were the basis of the predictive ability of the model. Notably, CA9 mRNA was significantly overexpressed in cervical carcinoma, tissues but not in normal cervix tissues. A pair of ceRNAs (CA9/ULBP2) could be involved in the carcinogenesis and development of cervical cancer, and the potential target might be hsa-miR-34a. In addition, predicted miRNAs and drugs for these DEGs were identified.

CONCLUSIONS

We constructed a prognostic model with good predictive performance, based on the expression of ferroptosis-related genes. Further research found that the ceRNA pairs of ULBP2/CA9 could regulate cervical cancer through hsa-miR-34a. These results identified the mechanism of ferroptosis in cervical cancer, and might provide novel therapeutics for cervical cancer patients.

SOD2 Enhancement by Long-Term Inhibition of the PI3K Pathway Confers Multi-Drug Resistance and Enhanced Tumor-Initiating Features in Head and Neck Cancer

The phosphoinositide-3-kinase (PI3K) pathway has widely been considered as a potential therapeutic target for head and neck cancer (HNC); however, the application of PI3K inhibitors is often overshadowed by the induction of drug resistance with unknown mechanisms. In this study, PII3K inhibitor resistant cancer cells were developed by prolonged culturing of cell lines with BEZ235, a dual PI3K and mammalian target of rapamycin (mTOR) inhibitor. The drug resistant HNC cells showed higher IC₅₀ of the proliferation to inhibitors specifically targeting PI3K and/or mTOR, as compared to their parental cells. These cells also showed profound resistance to drugs of other classes. Molecular analysis revealed persistent activation of phosphorylated AKT at threonine 308 in the drug resistant cells and increased expression of markers for tumor-initiating cells. Interestingly, increased intra-cellular ROS levels were observed in the drug resistant cells. Among anti-oxidant molecules, the expression of SOD2 was increased and was associated with the ALDH-positive tumor-initiating cell features. Co-incubation of SOD inhibitors and BEZ235 decreased the stemness feature of the cells in vitro, as shown by results of the spheroid formation assay. In conclusion, dysregulation of SOD2 might contribute to the profound resistance to PI3K inhibitors and the other drugs in HNC cells.

Targeting autophagy in disease: established and new strategies

Macroautophagy/autophagy is an evolutionarily conserved pathway responsible for clearing cytosolic aggregated proteins, damaged organelles or invading microorganisms. Dysfunctional autophagy leads to pathological accumulation of the cargo, which has been linked to a range of human diseases, including neurodegenerative diseases, infectious and autoimmune diseases and various forms of cancer. Cumulative work in animal models, application of genetic tools and pharmacologically active compounds, has suggested the potential therapeutic value of autophagy modulation in disease, as diverse as Huntington, Salmonella infection, or pancreatic cancer. Autophagy activation versus inhibition strategies are being explored, while the role of autophagy in pathophysiology is being studied in parallel. However, the progress of preclinical and clinical development of autophagy modulators has been greatly hampered by the paucity of selective pharmacological agents and biomarkers to dissect their precise impact on various forms of autophagy and cellular responses. Here, we summarize established and new strategies in autophagy-related drug discovery and indicate a path toward establishing a more efficient discovery of autophagy-selective pharmacological agents. With this knowledge at hand, modern concepts for therapeutic exploitation of autophagy might become more plausible.

Abbreviations: ALS: amyotrophic lateral sclerosis; AMPK: AMP-activated protein kinase; ATG: autophagy-related gene; AUTAC: autophagy-targeting chimera; CNS: central nervous system; CQ: chloroquine; GABARAP: gamma-aminobutyric acid type A receptor-associated protein; HCQ: hydroxychloroquine; LYTAC: lysosome targeting chimera; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTOR: mechanistic target of rapamycin kinase; NDD: neurodegenerative disease; PDAC: pancreatic ductal adenocarcinoma; PE: phosphatidylethanolamine; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; PROTAC: proteolysis-targeting chimera; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; SQSTM1/p62: sequestosome 1; ULK1: unc-51 like autophagy activating kinase 1.

Small molecules in targeted cancer therapy: advances, challenges, and future perspectives

Due to the advantages in efficacy and safety compared with traditional chemotherapy drugs, targeted therapeutic drugs have become mainstream cancer treatments. Since the first tyrosine kinase inhibitor imatinib was approved to enter the market by the US Food and Drug Administration (FDA) in 2001, an increasing number of small-molecule targeted drugs have been developed for the treatment of malignancies. By December 2020, 89 small-molecule targeted antitumor drugs have been approved by the US FDA and the National Medical Products Administration (NMPA) of China. Despite great progress, small-molecule targeted anti-cancer drugs still face many challenges, such as a low response rate and drug resistance. To better promote the development of targeted anti-cancer drugs, we conducted a comprehensive review of small-molecule targeted anti-cancer drugs according to the target classification. We present all the approved drugs as well as important drug candidates in clinical trials for each target, discuss the current challenges, and provide insights and perspectives for the research and development of anti-cancer drugs.

Structural optimization towards promising β-methyl-4-acrylamido quinoline derivatives as PI3K/mTOR dual inhibitors for anti-cancer therapy: The in vitro and in vivo biological evaluation

Built upon the 4-acrylamido quinoline derivative 4, a previously discovered PI3K/mTOR dual inhibitor, structural modification was undertaken in this study with the attempt to improve its oral exposure via introducing steric hindrance to the 4-acrylamido functionality. Consequently, 14d, as the representative among the synthesized compounds, exhibited IC₅₀ values of 0.80, 0.67, 1.30, 1.30 and 5.0 nM against PI3Kα, PI3Kβ, PI3Kγ, PI3Kδ and mTOR, respectively. Besides, 14d displayed comparable anti-proliferative activity against both PC3 and U87MG cell lines to that of the positive reference GSK2126458 with respective GI₅₀ value of 0.36 and 0.14 μM. Kinase selectivity assay showed that 14d was selective to PI3K family. In U87MG cells, 14d can strongly down-regulate PI3K/Akt/mTOR pathway via blocking both PI3K and mTOR signaling at the concentration as low as 25 nM. Importantly, following a PO dose of 5 mg/kg in male SD rats, 14d displayed favorable oral exposure (AUC_0-t = 1336.16 h × ng/mL, AUC_0-∞ = 1447.63 h × ng/mL) and high maximum plasma concentration (C_max = 903.00 ng/mL). In a U87MG glioblastoma xenograft model, tumor growth inhibition of 93.5% and tumor regression were observed at PO dose of 30 and 60 mg/kg, respectively. Meanwhile, no overt loss of body weight was observed in the 14d-treated groups. Taken together, 14d, by virtue of its attractive performance, merits further development as a potential anti-tumor candidate.

Deciphering the Role of Autophagy in Treatment of Resistance Mechanisms in Glioblastoma

Autophagy is a process essential for cellular energy consumption, survival, and defense mechanisms. The role of autophagy in several types of human cancers has been explicitly explained; however, the underlying molecular mechanism of autophagy in glioblastoma remains ambiguous. Autophagy is thought to be a “double-edged sword”, and its effect on tumorigenesis varies with cell type. On the other hand, autophagy may play a significant role in the resistance mechanisms against various therapies. Therefore, it is of the utmost importance to gain insight into the molecular mechanisms deriving the autophagy-mediated therapeutic resistance and designing improved treatment strategies for glioblastoma. In this review, we discuss autophagy mechanisms, specifically its pro-survival and growth-suppressing mechanisms in glioblastomas. In addition, we try to shed some light on the autophagy-mediated activation of the cellular mechanisms supporting radioresistance and chemoresistance in glioblastoma. This review also highlights autophagy’s involvement in glioma stem cell behavior, underlining its role as a potential molecular target for therapeutic interventions.

Combating TKI resistance in CML by inhibiting the PI3K/Akt/mTOR pathway in combination with TKIs: a review

Chronic myeloid leukemia (CML), a myeloproliferative hematopoietic cancer, is caused by a genetic translocation between chromosomes 9 and 22. This translocation produces a small Philadelphia chromosome, which contains the Bcr-Abl oncogene. The Bcr-Abl oncogene encodes the BCR-ABL protein, upregulates various signaling pathways (JAK-STAT, MAPK/ERK, and PI3K/Akt/mTOR), and out of which the specifically highly active pathway is the PI3K/Akt/mTOR pathway. Among early treatments for CML, tyrosine kinase inhibitors (TKIs) were found to be the most effective, but drug resistance against kinase inhibitors led to the discovery of novel alternative therapies. At this point, the PI3K/Akt/mTOR pathway components became new targets due to stimulation of this pathway in TKIs-resistant CML patients. The current review article deals with reviewing the scientific literature on the PI3K/Akt/mTOR pathway inhibitors listed in the National Cancer Institute (NCI) drug dictionary and proved effective against multiple cancers. And out of those enlisted inhibitors, the US FDA has also approved some PI3K inhibitors (Idelalisib, Copanlisib, and Duvelisib) and mTOR inhibitors (Everolimus, Sirolimus, and Temsirolimus) for cancer therapy. So far, several inhibitors have been tested, and further investigations are still ongoing. Even in Imatinib, Nilotinib, and Ponatinib-resistant CML cells, a dual PI3K/mTOR inhibitor, BEZ235, showed antiproliferative activity. Therefore, by considering the literature data of these reviews and further examining some of the reported inhibitors, which proved effective against the PI3K/Akt/mTOR signaling pathway in multiple cancers, may improve the therapeutic approaches towards TKI-resistant CML cells where the respective signaling pathway gets upregulated.

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

The HLTF-PARP1 interaction in the progression and stability of damaged replication forks caused by methyl methanesulfonate

Human HLTF participates in the lesion-bypass mechanism through the fork reversal structure, known as template switching of post-replication repair. However, the mechanism by which HLTF promotes the replication progression and fork stability of damaged forks remains unclear. Here, we identify a novel protein–protein interaction between HLTF and PARP1. The depletion of HLTF and PARP1 increases chromosome breaks, further reduces the length of replication tracks, and concomitantly increases the number of stalled forks after methyl methanesulfonate treatment according to a DNA fiber analysis. The progression of replication also depends on BARD1 in the presence of MMS treatment. By combining 5-ethynyl-2′-deoxyuridine with a proximity ligation assay, we revealed that the HLTF, PARP1, and BRCA1/BARD1/RAD51 proteins were initially recruited to damaged forks. However, prolonged stalling of damaged forks results in fork collapse. HLTF and PCNA dissociate from the collapsed forks, with increased accumulation of PARP1 and BRCA1/BARD1/RAD51 at the collapsed forks. Our results reveal that HLTF together with PARP1 and BARD1 participates in the stabilization of damaged forks, and the PARP1–BARD1 interaction is further involved in the repair of collapse forks.

Dacomitinib and gedatolisib in combination with fractionated radiation in head and neck cancer

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We evaluated radiation with dual EGFR and PI3K targeting in head and neck cancer.

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Dacomitinib, showed an inverse correlation between growth inhibition and EGFR expression.

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Gedatolisib was effective in each cell line. Neither drug caused radiosensitization in vitro.

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Gedatolisib was relatively ineffective in vivo in combination with dacomitinib and/or radiation.

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Dacomitinib was highly effective alone and in combination with radiation and/or gedatolisib.

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Immunoblotting studies in vivo mirrored the effects seen with growth delay.

Background and purpose

There has been little success targeting individual genes in combination with radiation in head and neck cancer. In this study we investigated whether targeting two key pathways simultaneously might be more effective.

Materials and methods

We studied the effect of combining dacomitinib (pan-HER, irreversible inhibitor) and gedatolisib (dual PI3K/MTOR inhibitor) with radiation in well characterized, low passage xenograft models of HNSCC in vitro and in vivo.

Results

Dacomitinib showed differential growth inhibition in vitro that correlated to EGFR expression whilst gedatolisib was effective in both cell lines. Neither agent radiosensitized the cell lines in vitro. In vivo studies demonstrated that dacomitinib was an effective agent alone and in combination with radiation whilst the addition of gedatolisib did not enhance the effect of these two modalities despite inhibiting phosphorylation of key genes in the PI3K/MTOR pathway.

Conclusions

Our results showed that combining two drugs with radiation provided no added benefit compared to the single most active drug. Dacomitinib deserves more investigation as a radiation sensitizing agent in HNSCC.

Quinoline-Based Molecules Targeting c-Met, EGF, and VEGF Receptors and the Proteins Involved in Related Carcinogenic Pathways

The quinoline ring system has long been known as a versatile nucleus in the design and synthesis of biologically active compounds. Currently, more than one hundred quinoline compounds have been approved in therapy as antimicrobial, local anaesthetic, antipsychotic, and anticancer drugs. In drug discovery, indeed, over the last few years, an increase in the publication of papers and patents about quinoline derivatives possessing antiproliferative properties has been observed. This trend can be justified by the versatility and accessibility of the quinoline scaffold, from which new derivatives can be easily designed and synthesized. Within the numerous quinoline small molecules developed as antiproliferative drugs, this review is focused on compounds effective on c-Met, VEGF (vascular endothelial growth factor), and EGF (epidermal growth factor) receptors, pivotal targets for the activation of important carcinogenic pathways (Ras/Raf/MEK and PI3K/AkT/mTOR). These signalling cascades are closely connected and regulate the survival processes in the cell, such as proliferation, apoptosis, differentiation, and angiogenesis. The antiproliferative biological data of remarkable quinoline compounds have been analysed, confirming the pivotal importance of this ring system in the efficacy of several approved drugs. Furthermore, in view of an SAR (structure-activity relationship) study, the most recurrent ligand–protein interactions of the reviewed molecules are summarized.

Design, synthesis and biological evaluation of thieno[3,2-d]pyrimidine derivatives containing aroyl hydrazone or aryl hydrazide moieties for PI3K and mTOR dual inhibition

Recently, PI3K and mTOR have been regarded as promising targets for cancer treatment. Herein, we designed and synthesized four series of novel thieno[3,2-d]pyrimidine derivatives that containing aroyl hydrazone or aryl hydrazide moieties. These derivatives act as PI3K/mTOR dual inhibitors, suggesting that they can be used as cancer therapeutic agents. All compounds were tested for anti-proliferative activity against four cancer cell lines. The structure-activity relationship (SAR) studies were conducted by varying the moieties at the C-6 and C-2 positions of the thieno[3,2-d]pyrimidine core. It indicated that aryl hydrazide at C-6 position and 2-aminopyrimidine at C-2 position are optimal fragments. Compound 18b showed the most potent in vitro activity (PI3Kα IC₅₀ = 0.46 nM, mTOR IC₅₀ = 12 nM), as well as good inhibition against PC-3 (human prostate cancer), HCT-116 (human colorectal cancer), A549 (human lung adenocarcinoma) and MDA-MB-231 (human breast cancer) cell lines. Furthermore, Annexin-V and propidium iodide (PI) double staining confirmed that 18b induces apoptosis in cytotoxic HCT-116 cells. Moreover, the influence of 18b on cell cycle distribution was assessed on the HCT-116 cell line, and a cell cycle arrest was observed at the G₁/S phases.

Research progress of mTOR inhibitors

Mammalian target of rapamycin (mTOR) is a highly conserved Serine/Threonine (Ser/Thr) protein kinase, which belongs to phosphatidylinositol-3-kinase-related kinase (PIKK) protein family. mTOR exists as two types of protein complex: mTORC1 and mTORC2, which act as central controller regulating processes of cell metabolism, growth, proliferation, survival and autophagy. The mTOR inhibitors block mTOR signaling pathway, producing anti-inflammatory, anti-proliferative, autophagy and apoptosis induction effects, thus mTOR inhibitors are mainly used in cancer therapy. At present, mTOR inhibitors are divided into four categories: Antibiotic allosteric mTOR inhibitors (first generation), ATP-competitive mTOR inhibitors (second generation), mTOR/PI3K dual inhibitors (second generation) and other new mTOR inhibitors (third generation). In this article, these four categories of mTOR inhibitors and their structures, properties and some clinical researches will be introduced. Among them, we focus on the structure of mTOR inhibitors and try to analyze the structure-activity relationship. mTOR inhibitors are classified according to their chemical structure and their contents are introduced systematically. Moreover, some natural products that have direct or indirect mTOR inhibitory activities are introduced together. In this article, we analyzed the target, binding mode and structure-activity relationship of each generation of mTOR inhibitors and proposed two hypothetic scaffolds (the inverted-Y-shape scaffold and the C-shape scaffold) for the second generation of mTOR inhibitors. These findings may provide some help or reference for drug designing, drug modification or the future development of mTOR inhibitor.

In Vitro and in Vivo Activity of mTOR Kinase and PI3K Inhibitors Against Leishmania donovani and Trypanosoma brucei

Kinetoplastid parasites, including Leishmania and Trypanosoma spp., are life threatening pathogens with a worldwide distribution. Next-generation therapeutics for treatment are needed as current treatments have limitations, such as toxicity and drug resistance. In this study, we examined the activities of established mammalian target of rapamycin (mTOR)/phosphoinositide 3-kinase (PI3K) inhibitors against these tropical diseases. High-throughput screening of a library of 1742 bioactive compounds against intracellular L. donovani was performed, and seven mTOR/PI3K inhibitors were identified. Dose-dilution assays revealed that these inhibitors had half maximal effective concentration (EC₅₀₎ values ranging from 0.14 to 13.44 μM for L. donovani amastigotes and from 0.00005 to 8.16 μM for T. brucei. The results of a visceral leishmaniasis mouse model indicated that treatment with Torin2, dactolisib, or NVP-BGT226 resulted in reductions of 35%, 53%, and 54%, respectively, in the numbers of liver parasites. In an acute T. brucei mouse model using NVP-BGT226 parasite numbers were reduced to under the limits of detection by five consecutive days of treatment. Multiple sequence and structural alignment results indicated high similarities between mTOR and kinetoplastid TORs; the inhibitors are predicted to bind in a similar manner. Taken together, these results indicated that the TOR pathways of parasites have potential for the discovery of novel targets and new potent inhibitors.

Epidermal growth factor-induced COX-2 regulates metastasis of head and neck squamous cell carcinoma through upregulation of angiopoietin-like 4

Epidermal growth factor receptor (EGFR) expression and activation are the major causes of metastasis in cancers such as head and neck squamous cell carcinoma (HNSCC). However, the reciprocal effect of EGF‐induced COX‐2 and angiopoietin‐like 4 (ANGPTL4) on HNSCC metastasis remains unclear. In this study, we revealed that the expression of ANGPTL4 is essential for COX‐2‐derived prostaglandin E₂ (PGE₂)‐induced tumor cell metastasis. We showed that EGF‐induced ANGPTL4 expression was dramatically inhibited with the depletion and inactivation of COX‐2 by knockdown of COX‐2 and celecoxib treatment, respectively. Prostaglandin E₂ induced ANGPTL4 expression in a time‐ and dose‐dependent manners in various HNSCC cell lines through the ERK pathway. In addition, the depletion of ANGPTL4 and MMP1 significantly impeded the PGE₂‐induced transendothelial invasion ability of HNSCC cells and the binding of tumor cells to endothelial cells. The induction of molecules involved in the regulation of epithelial‐mesenchymal transition was also dependent on ANGPTL4 expression in PGE₂‐treated cells. The depletion of ANGPTL4 further blocked PGE₂‐primed tumor cell metastatic seeding of lungs. These results indicate that the EGF‐activated PGE₂/ANGPTL4 axis enhanced HNSCC metastasis. The concurrent expression of COX‐2 and ANGPTL4 in HNSCC tumor specimens provides insight into potential therapeutic targets for the treatment of EGFR‐associated HNSCC metastasis.

Phase I study of BGT226, a pan-PI3K and mTOR inhibitor, in Japanese patients with advanced solid cancers

The phosphatidylinositol 3-kinase (PI3K) pathway is a promising therapeutic target for various cancers. BGT226 is a pan-PI3K and mammalian target of rapamycin (mTOR) inhibitor. The tolerability and pharmacokinetics/pharmacodynamics of BGT226 were investigated in a phase I study in Japanese patients with advanced solid cancers. BGT226 was orally administered on days 1, 3, and 5 of each week. The initial dose of 10 mg was subsequently escalated to 20, 40, 80, and 100 mg in a cohort of three patients. Pharmacokinetics and pharmacodynamics were investigated using plasma, normal skin, and tumor samples. A total of 18 patients were enrolled and evaluated. The most frequently reported toxicities were diarrhea, nausea, decreased appetite, vomiting, and fatigue. They were all grade 1 or 2, and no dose-limiting toxicity was observed. However, all six patients treated at 100 mg experienced diarrhea and nausea, while two experienced a dose reduction and/or interruptions during the study. Two of five patients who exhibited stable disease continued the study treatment for ≥ 16 weeks. The absorption of BGT226 was rapid, and systemic exposure increased in a dose-dependent manner. Treatment with BGT226 did not change any of the biomarkers in neither normal skin nor tumor tissues. BGT226 was tolerated up to 100 mg three times a week in Japanese patients with solid cancers, without difference in toxicity profiles and pharmacokinetics compared to Western patients.

Chemoproteomic Selectivity Profiling of PIKK and PI3K Kinase Inhibitors

Chemical proteomic approaches utilizing immobilized, broad-selective kinase inhibitors (Kinobeads) have proven valuable for the elucidation of a compound's target profile under close-to-physiological conditions and often revealed potentially synergistic or toxic off-targets. Current Kinobeads enrich more than 300 native protein kinases from cell line or tissue lysates but do not systematically cover phosphatidylinositol 3-kinases (PI3Ks) and phosphatidylinositol 3-kinase-related kinases (PIKKs). Some PIKKs and PI3Ks show aberrant activation in many human diseases and are indeed validated drug targets. Here, we report the development of a novel version of Kinobeads that extends kinome coverage to these proteins. This is achieved by inclusion of two affinity probes derived from the clinical PI3K/MTOR inhibitors Omipalisib and BGT226. We demonstrate the utility of the new affinity matrix by the profiling of 13 clinical and preclinical PIKK/PI3K inhibitors. The large discrepancies between the PI3K affinity values obtained and reported results from recombinant assays led us to perform a phosphoproteomic experiment showing that the chemoproteomic assay is the better approximation of PI3K inhibitor action in cellulo. The results further show that NVP-BEZ235 is not a PI3K inhibitor. Surprisingly, the designated ATM inhibitor CP466722 was found to bind strongly to ALK2, identifying a new chemotype for drug discovery to treat fibrodysplasia ossificans progressiva.

Bi2 S3 -Tween 20 Nanodots Loading PI3K Inhibitor, LY294002, for Mild Photothermal Therapy of LoVo Cells In Vitro and In Vivo

Although various types of photothermal agents are developed for photothermal cancer therapy, relatively few photothermal agents exhibit high tumor inhibition rate under relatively mild conditions. Herein, a multifunctional Bi₂ S₃ -Tween 20 nanoplatform loaded with PI3K inhibitor LY294002 is designed as a novel photothermal agent for inhibitor and photothermal synergistic therapy of tumors under mild photothermal therapy conditions. The LY294002 of PI3K inhibitor, after being loaded by Bi₂ S₃ -Tween 20 nanodots, exhibits greatly increased drug utilization and reduced side effects on normal tissues. In vivo, Bi₂ S₃ -Tween 20@LY294002 upon near-infrared 808 nm laser irradiation shows potent antitumor activity under relatively mild conditions (power density: 0.6 W cm^-2 ). Moreover, the mechanism studies also demonstrate that Bi₂ S₃ -Tween 20@LY294002 potently kills LoVo cancer cells under low-power near-infrared light irradiation, by downregulating the expression of heat shock protein 70 (HSP70) so as to increase the sensitivity of tumor cell hyperthermia and activating BAX/BAK-regulated mitochondrial apoptosis pathway. The results demonstrate that the newly synthesized multifunctional nanoplatform paves a new avenue for accurate therapy of photothermal-resistant cancer.

Protein Tyrosine Signaling and its Potential Therapeutic Implications in Carcinogenesis

Protein tyrosine phosphorylation is a crucial signaling mechanism that plays a role in epithelial carcinogenesis. Protein tyrosine kinases (PTKs) control various cellular processes including growth, differentiation, metabolism, and motility by activating major signaling pathways including STAT3, AKT, and MAPK. Genetic mutation of PTKs and/or prolonged activation of PTKs and their downstream pathways can lead to the development of epithelial cancer. Therefore, PTKs became an attractive target for cancer prevention. PTK inhibitors are continuously being developed, and they are currently used for the treatment of cancers that show a high expression of PTKs. Protein tyrosine phosphatases (PTPs), the homeostatic counterpart of PTKs, negatively regulate the rate and duration of phosphotyrosine signaling. PTPs initially were considered to be only housekeeping enzymes with low specificity. However, recent studies have demonstrated that PTPs can function as either tumor suppressors or tumor promoters, depending on their target substrates. Together, both PTK and PTP signal transduction pathways are potential therapeutic targets for cancer prevention and treatment.

In vitro effects of PI3K/mTOR inhibition in canine hemangiosarcoma

While extremely rare in humans, hemangiosarcoma (HSA) accounts for nearly 2% of canine neoplasia, and is characterized by both aggressive local growth/invasion and a high rate of metastasis. Both canine and human HSA exhibit sustained aberrant PI3K/Akt/mTOR pathway signaling. The purpose of this study was to examine the in vitro effects of a novel dual PI3K/mTOR inhibitor, VDC-597, in three canine HSA cell lines (DEN-, CIN-, and SB-HSA). VDC-597 suppressed activation of both Akt and 4eBP1 in canine HSA cells in a dose-dependent fashion, with an IC50 of approximately 0.3 uM, a concentration predicted to be clinically achievable based on preliminary early-phase canine and human studies. VDC-597 dose-dependently reduced proliferation, migration, and vascular endothelial growth factor production in HSA cells, while promoting tumor cell apoptosis. VDC-597 demonstrated additive antiproliferative effects when combined with doxorubicin. These results suggest that inhibitors of the PI3K/mTOR pathway may act against multiple components of the neoplastic process, including proliferation/apoptosis, chemosensitivity, migration, and angiogenesis, and justify the evaluation of PI3K/mTOR inhibitors in canine, and potentially human, HSA.

Design, Synthesis and Biological Evaluation of Novel Phenylsulfonylurea Derivatives as PI3K/mTOR Dual Inhibitors

Five series of novel phenylsulfonylurea derivatives, 19a⁻d, 20a⁻d, 21a⁻d, 22a⁻d and 23a⁻d, bearing 4-phenylaminoquinoline scaffold were designed, synthesized and their IC₅₀ values against four cancer cell lines (HepG-2, A549, PC-3 and MCF-7) were evaluated. Most compounds showed moderate cytotoxicity activity against the cancer cell lines. Structure⁻activity relationships (SARs) and pharmacological results indicated that introduction of 4-aminoquinoline scaffold and phenylsulfonylurea scaffold were beneficial for anti-tumor activity. Moreover, para-methoxyl substitution of 4-anilino moiety and para-halogen substitution of phenylsulfonylurea have different impacts on different series of compounds. Furthermore, the micromolecule group substitution in the 6-position of the quinoline ring have a slight impact on the cellular activity of the target compounds.

Acid-Promoted Cascade Reaction of N-(4-Chloroquinolin-3-yl)carbamates with Amines: One-Pot Assembly of Imidazo[4,5-c]quinolin-2-one

An acid-promoted cascade reaction of 4-chloroquinolin-3-yl carbamates with amines is described. This method achieves the formation of two new C-N bonds through an intermolecular amination/intramolecular cyclization reaction sequence. In combination with subsequent Suzuki coupling, this three-component telescopic procedure provides rapid access to various bioactive imidazo[4,5-c]quinolin-2-one derivatives.

Healthy CD4+ T lymphocytes are not affected by targeted therapies against the PI3K/Akt/mTOR pathway in T-cell acute lymphoblastic leukemia

An attractive molecular target for novel anti-cancer therapies is the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway which is commonly deregulated in many types of cancer. Nevertheless, the effects of PI3K/Akt/mTOR inhibitors on T lymphocytes, a key component of immune responses, have been seldom explored. In this study we investigated the effects on human CD4+ T-cells of a panel of PI3K/Akt/mTOR inhibitors: BGT226, Torin-2, MK-2206, and ZSTK474. We also assessed their efficacy against two acute leukemia T cell lines. T lymphocytes were stimulated with phytohemagglutinin. Inhibitor effects on cell cycle and apoptosis were analyzed by flow cytometry, while cytotoxicity was assessed by MTT assays. In addition, the activation status of the pathway as well as induction of autophagy were analyzed by Western blotting. Quiescent healthy T lymphocytes were unaffected by the drugs whereas mitogen-stimulated lymphocytes as well as leukemic cell lines displayed a cell cycle block, caspase-dependent apoptosis, and dephosphorylation of key components of the signaling pathway. Autophagy was also induced in proliferating lymphocytes and in JURKAT and MOLT-4 cell lines. When autophagy was inhibited by 3-methyladenine or Bafilomycin A1, drug cytotoxicity was increased, indicating that autophagy is a protective mechanism. Therefore, our findings suggest that PI3K/Akt/mTOR inhibitors preserve lymphocyte viability. This is a valuable result to be taken into account when selecting drugs for targeted cancer therapy in order to minimize detrimental effects on immune function.

Co-targeting PI3K, mTOR, and IGF1R with small molecule inhibitors for treating undifferentiated pleomorphic sarcoma

Undifferentiated pleomorphic sarcomas (UPSs) are aggressive mesenchymal malignancies with no definitive cell of origin or specific recurrent genetic hallmarks. These tumors are largely chemoresistant; thus, identification of potential therapeutic targets is necessary to improve patient outcome. Previous studies demonstrated that high expression of activated protein kinase B (AKT) in patients with UPS corresponds to poor disease-specific survival. Here, we demonstrate that inhibiting phosphatidylinositol-3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling using a small molecule inhibitor reduced UPS cell proliferation and motility and xenograft growth; however, increased phosphorylation of insulin-like growth factor 1 receptor (IGF1R) indicated the potential for adaptive resistance following treatment through compensatory receptor activation. Co-treatment with a dual PI3K/mTOR inhibitor and an anti-IGF1R kinase inhibitor reduced in vivo tumor growth rates despite a lack of antiproliferative effects in vitro. Moreover, this combination treatment significantly decreased UPS cell migration and invasion, which is linked to changes in p27 subcellular localization. Our results demonstrate that targeted inhibition of multiple components of the IGF1R/PI3K/mTOR pathway was more efficacious than single-agent therapy and suggest that co-targeting this pathway could be a beneficial therapeutic strategy for patients with UPS.

Antitumor activity of the dual PI3K/MTOR inhibitor, PF-04691502, in combination with radiation in head and neck cancer

BACKGROUND AND PURPOSE

Head and neck squamous cell carcinoma (HNSCC) remains a clinical challenge where new treatments are required to supplement the current-standard-of care of concurrent chemoradiation. The PI3K/AKT/MTOR pathway has been identified from several next generation DNA sequencing studies to be commonly altered and activated in HNSCC.

MATERIAL AND METHODS

In this study we investigated the activity of PF-04691502, an orally active ATP-competitive, dual inhibitor of PI3K and mTOR, in combination with a clinically relevant fractionated radiation treatment in two contrasting, well characterized, low passage HNSCC models.

RESULTS

We found that PF-04691502 combined synergistically with radiation in the UT-SCC-14 model derived from a primary cancer but was ineffective in the UT-SCC-15 model which was derived from a nodal recurrence. Further examination of the status of key signaling pathways combined with next generation DNA sequencing of a panel of 160 cancer-associated genes revealed crucial differences between the two models that could account for the differential effect. The UT-SCC-15 cell line was characterized by a higher mutational burden, an excess of variants in the PI3K/AKT/MTOR pathway, increased constitutive activity of PI3K, AKT1 and 2 and MTOR and an inability to inhibit key phosphorylation events in response to the treatments.

CONCLUSION

This study clearly highlights the promise of agents such as PF-04691502 in selected HNSCCs but also emphasizes the need for molecular characterization and alternative treatment strategies in non-responsive HNSCCs.

Chronic treatment with cisplatin induces chemoresistance through the TIP60-mediated Fanconi anemia and homologous recombination repair pathways

The Fanconi anemia pathway in coordination with homologous recombination is essential to repair interstrand crosslinks (ICLs) caused by cisplatin. TIP60 belongs to the MYST family of acetyltransferases and is involved in DNA repair and regulation of gene transcription. Although the physical interaction between the TIP60 and FANCD2 proteins has been identified that is critical for ICL repair, it is still elusive whether TIP60 regulates the expression of FA and HR genes. In this study, we found that the chemoresistant nasopharyngeal carcinoma cells, derived from chronic treatment of cisplatin, show elevated expression of TIP60. Furthermore, TIP60 binds to the promoters of FANCD2 and BRCA1 by using the chromatin immunoprecipitation experiments and promote the expression of FANCD2 and BRCA1. Importantly, the depletion of TIP60 significantly reduces sister chromatid exchange, a measurement of HR efficiency. The similar results were also shown in the FNACD2-, and BRCA1-deficient cells. Additionally, these TIP60-deficient cells encounter more frequent stalled forks, as well as more DNA double-strand breaks resulting from the collapse of stalled forks. Taken together, our results suggest that TIP60 promotes the expression of FA and HR genes that are important for ICL repair and the chemoresistant phenotype under chronic treatment with cisplatin.

Epidermal growth factor-induced pyruvate dehydrogenase kinase 1 expression enhances head and neck squamous cell carcinoma metastasis via up-regulation of fibronectin

Epidermal growth factor receptor (EGFR) activation is a major cause of metastasis in such cancers as head and neck squamous cell carcinoma (HNSCC); however, whether the metabolic enzyme, pyruvate dehydrogenase kinase 1 (PDK1), mediates EGF-enhanced HNSCC metastasis remains unclear. Of interest, we found that EGF induced PDK1 expression in HNSCC. Tumor cell transformation induced by EGF was repressed by PDK1 knockdown, and the down-regulation of PDK1 expression or inhibition of its activity significantly blocked EGF-enhanced cell migration and invasion. In addition, depletion of PDK1 impeded EGF-enhanced binding of HNSCC cells to endothelial cells as well as the metastatic seeding of tumor cells in lungs. PDK1 depletion inhibited EGF-induced matrix metalloproteinase-1 (MMP-1), MMP-2, MMP-3, MMP-9, and fibronectin expression and Rac1/cdc42 activation. Furthermore, PDK1 overexpression induced MMP-1, MMP-2, MMP-3, MMP-9, and fibronectin expression and Rac1/cdc42 activation. Of interest, depletion of fibronectin inhibited PDK1-enhanced MMP-1-3 and MMP-9 expression as well as Rac1/cdc42 activation and tumor invasion. These results demonstrate that EGF-induced PDK1 expression enhances HNSCC metastasis via activation of the fibronectin signaling pathway. Inhibition of PDK1 may be a potential strategy for the treatment of EGFR-mediated HNSCC metastasis.-Hsu, J.-Y., Chang, J.-Y., Chang, K.-Y., Chang, W.-C., Chen B.-K. Epidermal growth factor-induced pyruvate dehydrogenase kinase 1 expression enhances head and neck squamous cell carcinoma metastasis via up-regulation of fibronectin.

Discovery of a series of N-(5-(quinolin-6-yl)pyridin-3-yl)benzenesulfonamides as PI3K/mTOR dual inhibitors

Recently, the phosphoinositide 3-kinase (PI3K) and mammalian target of rapamycin (mTOR) have been considered as promising targets for the treatment of cancer. Herein, we synthesized a series of N-(5-(quinolin-6-yl)pyridin-3-yl)benzenesulfonamides as novel PI3K/mTOR dual inhibitors for cancer therapy. In the biological evaluation, compound 17e was identified as a potent PI3K/mTOR dual inhibitor, which significantly inhibit Class I PI3Ks, mTOR and phosphorylation of pAkt(Ser473) at low nanomolar level. Moreover, 17e display high potency against PC-3 cells (IC50 = 80 nM) in the anti-proliferative assay, and showed acceptable pharmacokinetic properties in vivo.

Design, synthesis, and biological evaluation of imidazo[1,2-b]pyridazine derivatives as mTOR inhibitors

ATP-competitive mTOR inhibitors have been studied as potential antitumor agents. Based on the structure-activity relationship of known mTOR inhibitors, a series of novel imidazo[1,2-b]pyridazine derivatives were synthesized and characterized. The anti-proliferative activities of these compounds were evaluated by SRB assay against six human cancer cell lines. Imidazo[1,2-b]pyridazine diaryl urea derivatives A15-A24 exhibited significant anti-proliferative activity especially against non-small cell lung cancer A549 and H460 with IC₅₀ values ranging from 0.02 μM to 20.7 μM. Among them, compounds A17 and A18 showed mTOR inhibitory activity with IC₅₀ of 0.067 μM and 0.062 μM, respectively. A more detailed analysis of compounds A17 and A18 showed that they induced G1-phase cell cycle arrest and suppressed the phosphorylation of AKT and S6 at cellular level. Moreover, obvious anticancer effect of A17 in vivo was observed in established nude mice A549 xenograft model.

Identification of 3-amidoquinoline derivatives as PI3K/mTOR dual inhibitors with potential for cancer therapy

A new series of 3-amidoquinoline derivatives were designed, synthesized and evaluated as PI3K/mTOR dual inhibitors.

Epidermal growth factor-induced ANGPTL4 enhances anoikis resistance and tumour metastasis in head and neck squamous cell carcinoma

Epidermal growth factor (EGF) is important for cancer cell proliferation, angiogenesis and metastasis in many types of cancer. However, the mechanisms involved in EGF-induced head and neck squamous cell carcinoma (HNSCC) metastasis remain largely unknown. In this study, we reveal that angiopoietin-like 4 (ANGPTL4) plays an important role in the regulation of EGF-induced cancer metastasis. We showed that EGF-induced ANGPTL4 expression promoted anoikis resistance and cancer cell migration and invasion in HNSCC. In addition, depletion of ANGPTL4 inhibited EGF-induced cancer cell invasion. Autocrine production of EGF-induced ANGPTL4 regulated the expression of matrix metalloproteinases (MMPs). The induction of MMP-1 gene expression by ANGPTL4-activated integrin β1 signalling occurred through the AP-1 binding site in the MMP-1 gene promoter. Furthermore, down-regulation of MMP-1 impeded EGF- and recombinant ANGPTL4-enhanced HNSCC cell migration and invasion. Depletion of ANGPTL4 significantly blocked EGF-primed extravasation and metastatic seeding of tumour cells and MMP-1 expression in lungs. However, no effect of ANGPTL4 on tumour growth was observed. These results suggest that EGF-induced expression and autocrine production of ANGPTL4 enhances HNSCC metastasis via the up-regulation of MMP-1 expression. Inhibition of ANGPTL4 expression may be a potential strategy for the treatment of EGFR-mediated HNSCC metastasis.

Discovery of Chromeno[4,3-c]pyrazol-4(2H)-one Containing Carbonyl or Oxime Derivatives as Potential, Selective Inhibitors PI3Kα

A series of novel chromeno[4,3-c]pyrazol-4(2H)-one containing carbonyl or oxime derivatives (4a-n, 5a-n) have been synthesized and evaluated their biological activities as phosphatidyl inositol 3-kinase (PI3K) inhibitors. Out of them, compound 5l showed the most potent antiproliferative activities against HCT-116 with IC₅₀ of 0.10 µM in vitro, and exhibited the most potent activity for PI3Kα with the value of 0.012 µM. Docking simulation of 5l into PI3Kα active site were performed to determine the probable binding model, and it indicated that compound 5l could be optimized as a potential inhibitor of PI3Kα in the further study.

The novel dual PI3K/mTOR inhibitor NVP-BGT226 displays cytotoxic activity in both normoxic and hypoxic hepatocarcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common lethal human malignancies worldwide and its advanced status is frequently resistant to conventional chemotherapeutic agents and radiation. We evaluated the cytotoxic effect of the orally bioavailable dual PI3K/mTOR inhibitor, NVP-BGT226, on a panel of HCC cell lines, since hyperactivated PI3K/Akt/mTOR signaling pathway could represent a biomolecular target for Small Inhibitor Molecules in this neoplasia. We analyzed the drug activity in both normoxia and hypoxia conditions, the latter playing often a relevant role in the induction of chemoresistance and angiogenesis.In normoxia NVP-BGT226 caused cell cycle arrest in the G0/G1 phase of the cell cycle, induced apoptosis and autophagy at low concentrations. Interestingly the drug inactivated p-Akt and p-S6 at < 10 nM concentration.In hypoxia NVP-BGT226 maintained its cytotoxic efficacy at the same concentration as documented by MTT assays and Western blot analysis. Moreover, the drug showed in hypoxia inhibitory properties against angiogenesis by lowering the expression of the transcription factor HIF-1α and of VEGF.Our results indicate that NVP-BGT226 has a potent cytotoxic effect on HCC cell lines also in hypoxia condition, thus emerging as a potential candidate for cancer treatment in HCC targeted therapy.