Sorafenib and sunitinib in the treatment of advanced non-small cell lung cancer

MCL1 inhibition: a promising approach to augment the efficacy of sorafenib in NSCLC through ferroptosis induction

Ferroptosis, an iron-dependent form of regulated cell death, plays a crucial role in modulating the therapeutic response in non-small cell lung cancer (NSCLC) patients. Studies have identified the signal transducer and activator of transcription 3 (STAT3) and myeloid cell leukemia-1 (MCL1) as potential targets for sorafenib, which exhibits activities in inducing ferroptosis. However, the role of STAT3-MCL1 axis in sorafenib-induced ferroptosis in NSCLC is still unclear. This study provided evidence that ferroptosis is a critical driver of sorafenib-induced cell death in NSCLC, supported by the accumulation of lipid peroxidation products, indicative of oxidative stress-induced cell death. Additionally, both in vitro and in vivo experiments showed that ferroptosis contributed to a significant portion of the anti-cancer effects elicited by sorafenib in NSCLC. The noticeable accumulation of lipid peroxidation products in sorafenib-treated mice underscored the significance of ferroptosis as a contributing factor to the therapeutic response of sorafenib in NSCLC. Furthermore, we identified the involvement of the STAT3/MCL1 axis in sorafenib-induced antitumor activity in NSCLC. Mechanistically, sorafenib inhibited endogenous STAT3 activation and downregulated MCL1 protein expression, consequently unleashing the ferroptosis driver BECN1 from the BECN1-MCL1 complex. Conversely, there is an augmented association of BECN1 with the catalytic subunit of system Xc-, SLC7A11, whose activity to import cystine and alleviate lipid peroxidation is hindered upon its binding with BECN1. Notably, we found that MCL1 upregulation correlated with ferroptosis resistance in NSCLC upon sorafenib treatment. Our findings highlight the importance of sorafenib-triggered ferroptosis in NSCLC and offer a novel strategy to treat advanced NSCLC patients: by downregulating MCL1 and, in turn, predispose NSCLC cells to ferroptosis.

Discovery of Potent Indolyl-Hydrazones as Kinase Inhibitors for Breast Cancer: Synthesis, X-ray Single-Crystal Analysis, and In Vitro and In Vivo Anti-Cancer Activity Evaluation

According to data provided by the World Health Organization (WHO), a total of 2.3 million women across the globe received a diagnosis of breast cancer in the year 2020, and among these cases, 685,000 resulted in fatalities. As the incidence of breast cancer statistics continues to rise, it is imperative to explore new avenues in the ongoing battle against this disease. Therefore, a number of new indolyl-hydrazones were synthesized by reacting the ethyl 3-formyl-1H-indole-2-carboxylate 1 with thiosemicarbazide, semicarbazide.HCl, 4-nitrophenyl hydrazine, 2,4-dinitrophenyl hydrazine, and 4-amino-5-(1H-indol-2-yl)-1,2,4-triazole-3-thione to afford the new hit compounds, which were assigned chemical structures as thiosemicarbazone 3, bis(hydrazine derivative) 5, semicarbzone 6, Schiff base 8, and the corresponding hydrazones 10 and 12 by NMR, elemental analysis, and X-ray single-crystal analysis. The MTT assay was employed to investigate the compounds' cytotoxicity against breast cancer cells (MCF-7). Cytotoxicity results disclosed potent IC50 values against MCF-7, especially compounds 5, 8, and 12, with IC50 values of 2.73 ± 0.14, 4.38 ± 0.23, and 7.03 ± 0.37 μM, respectively, compared to staurosproine (IC50 = 8.32 ± 0.43 μM). Consequently, the activities of compounds 5, 8, and 12 in relation to cell migration were investigated using the wound-healing test. The findings revealed notable wound-healing efficacy, with respective percentages of wound closure measured at 48.8%, 60.7%, and 51.8%. The impact of the hit compounds on cell proliferation was assessed by examining their apoptosis-inducing properties. Intriguingly, compound 5 exhibited a significant enhancement in cell death within MCF-7 cells, registering a notable increase of 39.26% in comparison to the untreated control group, which demonstrated only 1.27% cell death. Furthermore, the mechanism of action of compound 5 was scrutinized through testing against kinase receptors. The results revealed significant kinase inhibition, particularly against PI3K-α, PI3K-β, PI3K-δ, CDK2, AKT-1, and EGFR, showcasing promising activity, compared to standard drugs targeting these receptors. In the conclusive phase, through in vivo assay, compound 5 demonstrated a substantial reduction in tumor volume, decreasing from 106 mm³ in the untreated control to 56.4 mm³. Moreover, it significantly attenuated tumor proliferation by 46.9%. In view of these findings, the identified leads exhibit promises for potential development into future medications for the treatment of breast cancer, as they effectively hinder both cell migration and proliferation.

Augmented antitumor effects of erlotinib and cabozantinib on A549 non-small cell lung cancer: In vitro and in vivo studies

Non-small cell lung carcinoma is a challenging disease worldwide. This study aims to determine whether combining erlotinib, an epidermal growth factor receptor (EGFR) inhibitor, with cabozantinib, a mesenchymal-epithelial transition factor (c-Met) inhibitor, would have an augmented therapeutic benefit on A549 cells. The combination of erlotinib and cabozantinib (5 µM) inhibited A549 cell viability compared to each monotherapy at ≥ 10 µM as confirmed by the MTT assay. Combination therapy also has a more potent inhibition of cellular migration than monotherapy using the wound-healing assay. Furthermore, mRNA expression analyses for assessing apoptosis, metastasis, and cell cycle-related genes, the results showed that combination therapy significantly inhibits levels of BCL-2, MMP-9, VEGF, and TGF-β while inducing p53, p21, and BAX expression. In terms of oncogenic markers, western blotting analysis showed a significant reduction of BCl-2 expression and elevation in caspase3, p53, and p21 proteins as indicators of cell death via apoptosis. The antitumor in vivo effect of the combination therapy showed significant tumor inhibition compared to monotherapy. In conclusion, combination therapy could be a potential promising strategy to treat non-small cell lung carcinoma.

Immunotherapy and targeted therapy for lung cancer: Current status and future perspectives

Lung cancer has the highest incidence of morbidity and mortality throughout the globe. A large number of patients are diagnosed with lung cancer at the later stages of the disease. This eliminates surgery as an option and places complete dependence on radiotherapy or chemotherapy, and/or a combination of both, to halt disease progression by targeting the tumor cells. Unfortunately, these therapies have rarely proved to be effective, and this necessitates the search for alternative preventive approaches to reduce the mortality rate of lung cancer. One of the effective therapies against lung cancer comprises targeting the tumor microenvironment. Like any other cancer cells, lung cancer cells tend to use multiple pathways to maintain their survival and suppress different immune responses from the host's body. This review comprehensively covers the role and the mechanisms that involve the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in lung adenocarcinoma and methods of treating it by altering the tumor microenvironment. It focuses on the insight and understanding of the lung cancer tumor microenvironment and chemokines, cytokines, and activating molecules that take part in angiogenesis and metastasis. The review paper accounts for the novel and current immunotherapy and targeted therapy available for lung cancer in clinical trials and in the research phases in depth. Special attention is being paid to mark out single or multiple genes that are required for malignancy and survival while developing targeted therapies for lung cancer treatment.

Deciphering the key heterocyclic scaffolds in targeting microtubules, kinases and carbonic anhydrases for cancer drug development

Heterocyclic scaffolds are widely utilized for drug design by taking into account the molecular structure of therapeutic targets that are related to a broad spectrum of ailments, including tumors. Such compounds display various covalent and non-covalent interactions with the specific residues of the target proteins while causing their inhibition. There is a substantial number of heterocyclic compounds approved for cancer treatment, and these compounds function by interacting with different therapeutic targets involved in tumorogenesis. In this review, we trace and emphasize the privileged heterocyclic pharmacophores that have immense potency against several essential chemotherapeutic tumor targets: microtubules, kinases and carbonic anhydrases. Potent compounds currently undergoing pre-clinical and clinical studies have also been assessed for ascertaining the effective class of chemical scaffolds that have significant therapeutic potential against multiple malignancies. In addition, we also describe briefly the role of heterocyclic compounds in various chemotherapy regimens. The optimized molecular hybridization of delineated motifs may result in the discovery of more active anticancer therapeutics and circumvent the development of resistance by specific targets in the future.

Substituted oxindol-3-ylidenes as AMP-activated protein kinase (AMPK) inhibitors

AMP-activated protein kinase (AMPK) is a central metabolic regulator that promotes cancer growth and survival under hypoxia and plays a role in the maintenance of cancer stem cells. A major challenge to interrogating the potential of targeting AMPK in cancer is the lack of potent and selective small molecule inhibitors. Compound C has been widely used as an AMPK inhibitor, but it lacks potency and has a poor selectivity profile. The multi-kinase inhibitor, sunitinib, has demonstrated potent nanomolar inhibition of AMPK activity and has scope for modification. Here, we have designed and synthesized several series of oxindoles to determine the structural requirements for AMPK inhibition and to improve selectivity. We identified two potent, novel oxindole-based AMPK inhibitors that were designed to interact with the DFG motif in the ATP-binding site of AMPK, this key feature evades interaction with the common recptor tyrosine kinase targets of sunitinib. Cellular engagement of AMPK by these oxindoles was confirmed by the inhibition of phosphorylation of acetyl-CoA carboxylase (ACC), a known substrate of AMPK, in myeloid leukemia cells. Interestingly, although AMPK is highly expressed and activated in K562 cells these oxindole-based AMPK inhibitors did not impact cell viability or result in significant cytotoxicity. Our studies serve as a platform for the further development of oxindole-based AMPK inhibitors with therapeutic potential.

Vascular amounts and dispersion of caliber-classified vessels as key parameters to quantitate 3D micro-angioarchitectures in multiple myeloma experimental tumors

Blood vessel micro-angioarchitecture plays a pivotal role in tumor progression, metastatic dissemination and response to therapy. Thus, methods able to quantify microvascular trees and their anomalies may allow a better comprehension of the neovascularization process and evaluation of vascular-targeted therapies in cancer. To this aim, the development of a restricted set of indexes able to describe the arrangement of a microvascular tree is eagerly required. We addressed this goal through 3D analysis of the functional microvascular network in sulfo-biotin-stained human multiple myeloma KMS-11 xenografts in NOD/SCID mice. Using image analysis, we show that amounts, spatial dispersion and spatial relationships of adjacent classes of caliber-filtered microvessels provide a near-linear graphical “fingerprint” of tumor micro-angioarchitecture. Position, slope and axial projections of this graphical outcome reflect biological features and summarize the properties of tumor micro-angioarchitecture. Notably, treatment of KMS-11 xenografts with anti-angiogenic drugs affected position and slope of the specific curves without degrading their near-linear properties. The possibility offered by this procedure to describe and quantify the 3D features of the tumor micro-angioarchitecture paves the way to the analysis of the microvascular tree in human tumor specimens at different stages of tumor progression and after pharmacologic interventions, with possible diagnostic and prognostic implications.

Functional Biological Activity of Sorafenib as a Tumor-Treating Field Sensitizer for Glioblastoma Therapy

Glioblastoma, the most common primary brain tumor in adults, is an incurable malignancy with poor short-term survival and is typically treated with radiotherapy along with temozolomide. While the development of tumor-treating fields (TTFields), electric fields with alternating low and intermediate intensity has facilitated glioblastoma treatment, clinical outcomes of TTFields are reportedly inconsistent. However, combinatorial administration of chemotherapy with TTFields has proven effective for glioblastoma patients. Sorafenib, an anti-proliferative and apoptogenic agent, is used as first-line treatment for glioblastoma. This study aimed to investigate the effect of sorafenib on TTFields-induced anti-tumor and anti-angiogenesis responses in glioblastoma cells in vitro and in vivo. Sorafenib sensitized glioblastoma cells to TTFields, as evident from significantly decreased post-TTFields cell viability (p < 0.05), and combinatorial treatment with sorafenib and TTFields accelerated apoptosis via reactive oxygen species (ROS) generation, as evident from Poly (ADP-ribose) polymerase (PARP) cleavage. Furthermore, use of sorafenib plus TTFields increased autophagy, as evident from LC3 upregulation and autophagic vacuole formation. Cell cycle markers accumulated, and cells underwent a G2/M arrest, with an increased G0/G1 cell ratio. In addition, the combinatorial treatment significantly inhibited tumor cell motility and invasiveness, and angiogenesis. Our results suggest that combination therapy with sorafenib and TTFields is slightly better than each individual therapy and could potentially be used to treat glioblastoma in clinic, which requires further studies.

The novel PI3K inhibitor S1 synergizes with sorafenib in non-small cell lung cancer cells involving the Akt-S6 signaling

Non-small cell lung cancer (NSCLC) has been the major cause of cancer-related deaths worldwide. Targeted therapy has been available as an additive strategy for NSCLC patients, but the inevitable resistance to mono-targeted agents has largely hampered its usage in the clinic. We have previously designed and synthesized a novel small molecule compound S1, 2-methoxy-3-phenylsulfonamino-5-(quinazolin-6-yl) benzamides and demonstrated its inhibition of PI3K and mTOR as well as the anti-tumor potential. In the present study, we have identified that S1 alone or combined with the multi-kinase inhibitor sorafenib can inhibit the in vitro cell proliferation of NSCLC cells (A549, NCI-H157 and 95D cells) and tumor growth in the A549 xenograft model. S1 alone produced inhibitory effects on the colony formation, cell migration and invasion and angiogenesis, with more pronounced inhibition when used with sorafenib. We further revealed that S1 mainly inhibited the Akt/S6 phosphorylation while sorafenib mostly decreased the phosphorylation of ERK. Together, the novel PI3K/mTOR inhibitor S1 per se exhibits strong anti-tumor effects in NSCLC cells and A549 xenograft, effects possibly via its inhibition of cell proliferation, invasion and migration and angiogenesis. The combination of S1 and sorafenib exerts potentiated anti-tumor effects, in which the underlying mechanisms may involve their differential modulation of the phosphorylation of Akt and S6 in the PI3K/Akt/mTOR cascades and ERK phosphorylation in the Raf/MEK/ERK pathways. The combination of S1 and sorafenib could be used as an additive approach in treating NSCLC in the clinic.

Mechanisms, monitoring, and management of tyrosine kinase inhibitors-associated cardiovascular toxicities

The tyrosine kinase inhibitor (TKI) drug class is a prominently used option in the treatment of various cancers. Safety evaluation of these drugs has shown evidence of cardiotoxicity of varying frequency and severity between agents; concern has led to updated labeling, warning prescribers of such. This review seeks to clarify the present dangers and investigate cardiotoxic mechanisms of action for each discussed TKI. Dasatinib was connected primarily with an incidence of fluid retention, edema, QT prolongation, and pulmonary hypertension in clinical studies. It is theorized that this is due to a combination of off-target kinase binding and on-target binding of Bcr-Abl, and less likely, mitochondrial induced apoptosis. Studies showed sorafenib to carry the risk of hypertension, QT prolongation, and myocardial infarction. Proposed mechanisms for these side effects include inhibition of proteins, vascular endothelium growth factor receptor, hERG potassium channels, and the RAF/MERK/ERK pro-survival pathway. Finally, lapatinib showed evidence of decreased left ventricular ejection fraction (LVEF) and QT prolongation in clinical studies. The literature attributes these as side effects of on-target ErbB2 binding leading to mitochondrial induced apoptosis. The concern warranted by these findings is in question. Pooled safety data suggest that the overall risk for cardiotoxicity is minimal in dasatinib and lapatinib. Sorafenib seems to carry a moderate concern. For the discussed agents, recommendations agree that routine monitoring via methods such as electroencephalogram, cardiac biomarkers, and blood pressure is warranted during the course of treatment, in addition to a comprehensive collection of past medical history and risk factors to identify those at heightened risk for cardiovascular events.

Vascular endothelial growth factor (VEGF) antibody significantly increases the risk of hand-foot skin reaction to multikinase inhibitors (MKIs): A systematic literature review and meta-analysis

With the use of multikinase inhibitors (MKIs) having emerged in recent years, skin toxicities such as hand-foot skin reaction (HFSR) are primary side effects, and they lack effective prediction methods. Here, we updated a previous systematic review by establishing a meta-analysis of the risk of developing HFSR among patients receiving MKIs and antivascular endothelial growth factor antibody. Publications from PubMed and abstracts presented at the American Society of Clinical Oncology Annual Meeting up to February 5, 2015, were searched to identify relevant studies, and a total of 236 patients with metastatic tumours in nine trials were included for analysis. In the meta-analysis, the pooled incidence rates of all-grade and high-grade HFSR among patients who received the combination therapy were 56.9% [95% confidence interval (CI), 45%-71.1%] and 14.3% (95% CI, 9%-24.2%), respectively, with significant differences observed with MKI monotherapy (P < .05). Further subgroup analysis demonstrated that increasing the dosages of bevacizumab (77.8% vs 51.1%, P = .04) and MKIs (64.3% vs 52.6%, P = .02) significantly increased HFSR incidence. Moreover, combination with chemotherapy exerted a minimal effect on HFSR risk (61% vs 55.3%, P = .5). This updated review and meta-analysis confirm the increased risk of HFSR incidence due to the use of MKIs and antivascular endothelial growth factor antibody. Thus, using these therapies requires safety standards.

Synergistic antitumor activity of low-dose c-Met tyrosine kinase inhibitor and sorafenib on human non-small cell lung cancer cells

Sorafenib is a multikinase inhibitor that is frequently used to treat various types of malignant tumors. However, it has been demonstrated that Sorafenib only has a moderate antitumor efficacy and is associated with numerous side effects in non-small cell lung cancer (NSCLC), which greatly limits its clinical application. The present study aimed to examine the effects of a combination of Sorafenib and low-dose PF-2341066, a selective c-Met tyrosine kinase inhibitor, on the proliferation, apoptosis and migration of the NSCLC cell line NCI-H1993. The data indicated that treatment with a combination of Sorafenib and low-dose PF-2341066 was able to significantly inhibit the proliferation and migration as well as promote the apoptosis, of NCI-H1993 cells, compared with treatment with Sorafenib or low-dose PF-2341066 alone. Further experiments indicated that the levels of phosphorylated epidermal growth factor receptor and c-Met were significantly decreased following the combined treatment of Sorafenib and PF-2341066, compared with the treatment with Sorafenib or PF-2341066 alone. The findings of the present study indicated that using a low-dose c-Met inhibitor enhances the antitumor activity of Sorafenib in NSCLC and may provide a novel strategy for the treatment of NSCLC.

Cardio-Oncology: Cancer Therapy-related Cardiovascular Complications in a Molecular Targeted Era: New Concepts and Perspectives

Cardio-oncology is a medical discipline that identifies, prevents, and treats the cardiovascular complications related to cancer therapy. Due to the remarkable proliferation of new cancer therapies causing cardiovascular complications, such as hypertension, heart failure, vascular complications, and cardiac arrhythmia, we provide an extensive, comprehensive revision of the most up-to-date scientific information available on the cardiovascular complications associated with the use of newer, novel chemotherapeutic agents, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention. The authors consider this topic to be relevant for the clinicians since cardiovascular complications associated with the administration of recently approved drugs are relatively underappreciated. The purpose of this article is to provide a state-of-the-art review of cardiovascular complications associated with the use of newer, novel chemotherapeutic agents and targeted therapies, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention.  Ongoing efforts are needed to provide a better understanding of the frequency, mechanisms of disease, prevention, and treatment of cardiovascular complications induced by the newer, novel chemotherapeutic agents. Development of a cardio-oncology discipline is warranted in order to promote task forces aimed at the creation of oncology patient-centered guidelines for the detection, prevention, and treatment of potential cardiovascular side effects associated with newer cancer therapies.

Using gene expression database to uncover biology functions of 1,4-disubstituted 1,2,3-triazole analogues synthesized via a copper (I)-catalyzed reaction

We have synthesized bioactive 1,4-disubstituted 1,2,3-triazole analogues containing 2H-1,4-benzoxazin-3-(4H)-one derivatives via 1,3-dipolar cycloaddition in the presence of CuI. All the reactions proceeded smoothly and afforded its desired products in excellent yields. Among these analogues, 3y exhibited a better cytotoxic effect on human hepatocellular carcinoma (HCC) Hep 3B cells and displayed less cytotoxicity on normal human umbilical vein endothelial cells, compared with Sorafenib, a targeted therapy for advanced HCC. 3y also induced stronger apoptosis and autophagy. Addition of curcumin enhanced 3y-induced cytotoxicity by further induction of autophagy. Using gene expression signatures of 3y to query Connectivity Map, a glycogen synthase kinase-3 inhibitor (AR-A014418) was predicted to display similar molecular action of 3y. Experiments further demonstrate that AR-A014418 acted like 3y, and vice versa. Overall, our data suggest the chemotherapeutic potential of 3y on HCC.

Small-molecule inhibitor sorafenib regulates immunoreactions by inducing survival and differentiation of bone marrow cells

Sorafenib has been used for the treatment of liver cancer. However, its clinical impact on human immunity system remains poorly known. Our previous study has shown that sorafenib modulates immunosuppressive cell populations in murine liver cancer models. Here, we continue to report that low doses of sorafenib promotes the survival of murine bone marrow cells (BMCs) in a dose-dependent manner by up-regulating the anti-apoptotic protein survivin. Sorafenib induces differentiation of BMCs into suppressive dendritic cells that inhibit autologous T-cell proliferation and stimulate CD4+ T cells to express increased IL-1β, IL-2, IL-4, IL-10, IFN-γ and TNF-α, and reduced levels of IL-6 and CD25, which indicates that sorafenib-induced dendritic cells represent a distinct cellular subset with unique properties. Taken together, our findings suggest that in addition to its anticancer effects, sorafenib has an immunoregulatory property that is apparent at low doses.

Squamous Cell Carcinoma - Similarities and Differences among Anatomical Sites

Squamous cell carcinoma (SCC) is an epithelial malignancy involving many anatomical sites and is the most common cancer capable of metastatic spread. Development of early diagnosis methods and novel therapeutics are important for prevention and mortality reduction. In this effort, numerous molecular alterations have been described in SCCs. SCCs share many phenotypic and molecular characteristics, but they have not been extensively compared. This article reviews SCC as a disease, including: epidemiology, pathology, risk factors, molecular characteristics, prognostic markers, targeted therapy, and a new approach to studying SCCs. Through this comparison, several themes are apparent. For example, HPV infection is a common risk factor among the four major SCCs (NMSC, HNSC, ESCC, and NSCLC) and molecular abnormalities in cell-cycle regulation and signal transduction predominate. These data reveal that the molecular insights, new markers, and drug targets discovered in individual SCCs may shed light on this type of cancer as a whole.

Inhibition of myeloid cell leukemia-1: Association with sorafenib-induced apoptosis in human mucoepidermoid carcinoma cells and tumor xenograft

BACKGROUND

The purpose of our study was to investigate the anticancer effect of sorafenib on mucoepidermoid carcinoma (MEC) and find its new molecular mechanism.

METHODS

The apoptotic effects of sorafenib were performed using MTS assay, diamidino-phenylindole (DAPI) staining, Western blotting, reverse transcription-polymerase chain reaction (RT-PCR), siRNA, and xenograft.

RESULTS

Sorafenib had apoptotic effects on MC-3 and YD15 cells and decreased myeloid cell leukemia-1 (Mcl-1) through proteasome-dependent protein degradation and the inhibition of protein synthesis. Sorafenib significantly affected truncated bid (t-Bid) and siMcl-1 resulting in the upregulation of t-Bid to induce apoptosis. Signal transducer and activator of transcription 3 (STAT3) phosphorylation was also blocked by sorafenib and a potent STAT3 inhibitor, cryptotanshinone clearly induced poly ADP-ribose polymerase (PARP) cleavage by inhibiting Mcl-1 and increasing t-Bid. Finally, administration of sorafenib significantly suppressed tumor growth and induced apoptosis in tumor xenograft model in association with downregulation of Mcl-1 without any side effects.

CONCLUSION

Taken together, these findings suggest that sorafenib can be a good anticancer drug candidate for the treatment of MEC.

Non-small-cell lung cancer: molecular targeted therapy and personalized medicine - drug resistance, mechanisms, and strategies

Targeted therapies for cancer bring the hope of specific treatment, providing high efficacy and in some cases lower toxicity than conventional treatment. Although targeted therapeutics have helped immensely in the treatment of several cancers, like chronic myelogenous leukemia, colon cancer, and breast cancer, the benefit of these agents in the treatment of lung cancer remains limited, in part due to the development of drug resistance. In this review, we discuss the mechanisms of drug resistance and the current strategies used to treat lung cancer. A better understanding of these drug-resistance mechanisms could potentially benefit from the development of a more robust personalized medicine approach for the treatment of lung cancer.

Synthesis and biological activity of 5-chloro-N⁴-substituted phenyl-9H-pyrimido[4,5-b]indole-2,4-diamines as vascular endothelial growth factor receptor-2 inhibitors and antiangiogenic agents

Inhibition of receptor tyrosine kinase (RTK) signaling pathways is an important area for the development of novel anticancer agents. Numerous multikinase inhibitors (MKIs) have been recently approved for the treatment of cancer. Vascular endothelial growth factor receptor-2 (VEGFR-2) is the principal mediator of tumor angiogenesis. In an effort to develop ATP-competitive VEGFR-2 selective inhibitors the 5-chloro-N(4)-substituted phenyl-9H-pyrimido[4,5-b]indole-2,4-diamine scaffold was designed. The synthesis of the target compounds involved N-(4,5-dichloro-9H-pyrimido[4,5-b]indol-2-yl)-2,2-dimethylpropanamide) as a common intermediate. A nucleophilic displacement of the 4-chloro group of the common intermediate by appropriately substituted anilines afforded the target compounds. Biological evaluation indicated that compound 5 is a potent and selective VEGFR-2 inhibitor comparable to sunitinib and semaxinib.

N2-Trimethylacetyl substituted and unsubstituted-N4-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines: design, cellular receptor tyrosine kinase inhibitory activities and in vivo evaluation as antiangiogenic, antimetastatic and antitumor agents

Six novel N(4)-phenylsubstituted-6-(2-pyridin-2-ylethyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamines and their N(2)-trimethylacetyl substituted analogs were synthesized as receptor tyrosine kinase (RTK) inhibitors. A microwave-mediated Sonogashira reaction was used as a key step for the synthesis of these compounds. Biological evaluation, in whole cell assays, showed that some analogs had remarkable inhibitory activity against a variety of RTKs and in particular cytotoxic activity against A431 tumor cells in culture. The inhibitory data against RTKs in this study demonstrated that variation of the 4-anilino substituents of these analogs dictates both potency and specificity of inhibitory activity against various RTKs. The study also supported the hypothesis that interaction of substituents on the 2-amino group with hydrophobic site-II provides an increase in potency. Compound 8 of this series was selected for evaluation in vivo in a B16-F10 syngeneic mouse tumor model and exhibited significant reduction in tumor growth rate, in tumor vascular density and in metastases to the lung compared to the control.

Targeting VEGF signalling via the neuropilin co-receptor

The blockade of tumour vascularisation and angiogenesis continues to be a focus for drug development in oncology and other pathologies. Historically, targeting vascular endothelial growth factor (VEGF) activity and its association with VEGF receptors (VEGFRs) has represented the most promising line of attack. More recently, the recognition that VEGFR co-receptors, neuropilin-1 and -2 (NRP1 and NRP2), are also engaged by specific VEGF isoforms in tandem with the VEGFRs has expanded the landscape for the development of modulators of VEGF-dependent signalling. Here, we review the recent structural characterisation of VEGF interactions with NRP subdomains and the impact this has had on drug development activity in this area.

Sorafenib in non-small cell lung cancer

INTRODUCTION

Conventional chemotherapy has reached a plateau of effectiveness for the treatment of non-small cell lung cancer (NSCLC). Patients with EGFR mutation or ALK translocations will benefit significantly from agents targeting these pathways, however, only 20% of western NSCLC patients have these mutations. Anti-VEGF antibody bevacizumab was approved for advanced NSCLC, but the clinical benefits are modest and all patients eventually develop resistance. Multi-targeted tyrosine kinase inhibitors (TKI) may offer more efficient inhibition of angiogenesis by blocking overlapping pathways and they may also have direct anti-tumor effects. Sorafenib is approved in the treatment of renal cell carcinoma and hepatocellular carcinoma and is now under investigation in the treatment of NSCLC.

AREAS COVERED

This review summarizes recent studies evaluating sorafenib in the treatment of NSCLC.

EXPERT OPINION

Sorafenib has shown anti-tumor activity in NSCLC. However, because NSCLC is complex and molecularly heterogeneous, it is very likely that only a subset of NSCLC patients will benefit from sorafenib, and so it is imperative to discover biomarkers to select patients who will probably benefit from sorafenib. Combination with other agents targeting parallel and compensatory pathways, such as EGFR inhibitors, may offer broader coverage and better disease control.

Sorafenib inhibits endogenous and IL-6/S1P induced JAK2-STAT3 signaling in human neuroblastoma, associated with growth suppression and apoptosis

Neuroblastoma is the most common extracranial solid tumor in the pediatric population. Sorafenib (Nexavar), a multikinase inhibitor, blocks cell proliferation and induces apoptosis in certain types of cancers. Here, we tested antitumor effects of sorafenib (≤ 10 µM) on four human neuroblastoma cell lines, CHLA255, CHLA171, CHLA90 and SK-N-AS. Sorafenib inhibited cell proliferation and induced apoptosis of neuroblastoma tumor cells in a dose-dependent manner. Sorafenib inhibited phosphorylation of Signal Transducer and Activator of Transcription 3 (STAT3) proteins at Tyr705 in these cells, associated with inhibition of phosphorylated JAK2, an upstream kinase that mediates STAT3 phosphorylation. Expression of a constitutively-activated STAT3 mutant (pSTAT3-C) partially blocked the antitumor effects of sorafenib on neuroblastoma cells. Sorafenib also inhibited the phosphorylation of STAT3 induced by IL-6 and sphingosine-1-phosphate (S1P), a recently identified regulator for STAT3, in these tumor cells. Moreover, sorafenib downregulated phosphorylation of MAPK (p44/42) in neuroblastoma cells, consistent with inhibition of their upstream regulators MEK1/2. Sorafenib inhibited expression of cyclin E, cyclin D1/D2/D3, key regulators for cell cycle, and the antiapoptotic proteins Mcl-1 and survivin. Finally, sorafenib suppressed the growth of human neuroblastoma cells in a mouse xenograft model. Taken together, these findings suggest the potential use of sorafenib for the treatment of pediatric neuroblastomas.

The eligibility of advanced non-small-cell lung cancer patients for targeted therapy clinical trials

BACKGROUND

The selection criteria for phase III trials are often stringent. We aimed to determine how many advanced non-small-cell lung cancer (NSCLC) patients would have been eligible for phase III targeted therapy trials and the proportion receiving anticancer treatment.

PATIENTS AND METHODS

From March 2007 to May 2008, all advanced NSCLC patients presented at our lung cancer multidisciplinary team meeting were included to assess eligibility for the targeted therapy trials: ECOG-4599, AVAiL, FLEX, TALENT, INTACT-1, INTACT-2, ESCAPE, NEXUS and MONET1. Medical records were examined to determine treatment utilisation and overall survival.

RESULTS

A total of 62 patients were registered: 63% male; median age 71 years; 61% stage IIIB disease. Percentages that met criteria were: ECOG-4599 31%, AVAiL 24%, FLEX 69%, TALENT 27%, INTACT-1 50%, INTACT-2 42%, ESCAPE 39%, NEXUS 63% and MONET1 34%. Common reasons for ineligibility were insufficient life expectancy, poor performance status, abnormal bloods, proteinuria and associated cancer problems. Systemic therapies were received by 66% of patients and median survival was 10.3 months.

CONCLUSION

Only 24%-69% were eligible for targeted therapy trials but 66% received anticancer treatment. Clinical trials in patients with advanced NSCLC need to be more representative of the majority of patients.

Bortezomib induces apoptosis and growth suppression in human medulloblastoma cells, associated with inhibition of AKT and NF-ĸB signaling, and synergizes with an ERK inhibitor

Medulloblastoma is the most common brain tumor in children. Here, we report that bortezomib, a proteasome inhibitor, induced apoptosis and inhibited cell proliferation in two established cell lines and a primary culture of human medulloblastomas. Bortezomib increased the release of cytochrome c to cytosol and activated caspase-9 and caspase-3, resulting in cleavage of PARP. Caspase inhibitor (Z-VAD-FMK) could rescue medulloblastoma cells from the cytotoxicity of bortezomib. Phosphorylation of AKT and its upstream regulator mTOR were reduced by bortezomib treatment in medulloblastoma cells. Bortezomib increased the expression of Bad and Bak, pro-apoptotic proteins, and p21Cip1 and p27Kip1, negative regulators of cell cycle progression, which are associated with the growth suppression and induction of apoptosis in these tumor cells. Bortezomib also increased the accumulation of phosphorylated IĸBα, and decreased nuclear translocation of NF-ĸB. Thus, NF-ĸB signaling and activation of its downstream targets are suppressed. Moreover, ERK inhibitors or downregulating ERK with ERK siRNA synergized with bortezomib on anticancer effects in medulloblastoma cells. Bortezomib also inhibited the growth of human medulloblastoma cells in a mouse xenograft model. These findings suggest that proteasome inhibitors are potentially promising drugs for treatment of pediatric medulloblastomas.

N⁴-(3-Bromophenyl)-7-(substituted benzyl) pyrrolo[2,3-d]pyrimidines as potent multiple receptor tyrosine kinase inhibitors: design, synthesis, and in vivo evaluation

With the goal of developing multitargeted receptor tyrosine kinase inhibitors that display potent inhibition against PDGFRβ and VEGFR-2 we designed and synthesized eleven N(4)-(3-bromophenyl)-7-(substitutedbenzyl) pyrrolo[2,3-d]pyrimidines 9a-19a. These compounds were obtained from the key intermediate N(4)-(3-bromophenyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamine 29. Various arylmethyl groups were regiospecifically attached at the N7 of 29 via sodium hydride induced alkylation with substituted arylmethyl halides. Compounds 11a and 19a were potent dual inhibitors of PDGFRβ and VEGFR-2. In a COLO-205, in vivo tumor mouse model 11a demonstrated inhibition of tumor growth, metastasis, and tumor angiogenesis that was better than or comparable to the standard compound TSU-68 (SU6668, 8).

Multi-targeted tyrosine kinase inhibitors for the treatment of non-small cell lung cancer: an era of individualized therapy

Multi-targeted tyrosine kinase inhibitors (TKIs) have played an increasingly important role in the treatment of non-small cell lung cancer (NSCLC). Many recently published phase III trials have shown bittersweet efficacies of these drugs. How to optimize the efficacies of TKIs has been a hot topic in the era of individualized therapy. In this article, we review the up-to-dated advances in research on the application of TKIs for NSCLC treatment.

Multi-tyrosine kinase inhibitors in preclinical studies for pediatric CNS AT/RT: Evidence for synergy with Topoisomerase-I inhibition

BACKGROUND

Currently, Atypical Teratoid Rhabdoid Tumor (AT/RT) constitutes one of the most difficult to treat malignancies in pediatrics. Hence, new knowledge of potential targets for therapeutics and the development of novel treatment approaches are urgently needed. We have evaluated the presence of cytokine pathways and the effects of two clinically available multi-tyrosine kinase inhibitors for cytotoxicity, target modulation and drug combinability against AT/RT cell lines.

RESULTS

AT/RT cell lines expressed measurable quantities of VEGF, FGF, PDGF and SDF-1, although the absolute amounts varied between the cell lines. The targeted receptor tyrosine kinase inhibitor sorafenib inhibited the key signaling molecule Erk, which was activated following the addition of own conditioned media, suggesting the existence of autocrine/paracrine growth stimulatory pathways. The multi-tyrosine kinase inhibitors sorafenib and sunitinib also showed significant growth inhibition of AT/RT cells and their activity was enhanced by combination with the topoisomerase inhibitor, irinotecan. The loss of cytoplasmic NF-kappa-B in response to irinotecan was diminished by sorafenib, providing evidence for a possible benefit for this drug combination.

CONCLUSIONS

In addition to previously described involvement of insulin like growth factor (IGF) family of cytokines, a multitude of other growth factors may contribute to the growth and survival of AT/RT cells. However, consistent with the heterogeneous nature of this tumor, quantitative and qualitative differences may exist among different tumor samples. Multi-tyrosine kinase inhibitors appear to have effective antitumor activity against all cell lines studied. In addition, the target modulation studies and drug combinability data provide the groundwork for additional studies and support the evaluation of these agents in future treatment protocols.

[Current status and future direction of multi-targeted drugs in the era of personalized therapy--overview of advances in multi-targeted therapy in non-small cell lung cancer]

Multi-targeted tyrosine kinase inhibitors (TKIs) play important roles in the treatment of non-small cell lung cancer (NSCLC). Recently, results of several large phase III studies have been published, showing bittersweet efficacy of multi-targeted TKIs. In the era of personalized therapy, optimal use of multi-targeted TKIs is worthy of further investigation. In this review, we summarized current clinical development and future direction of multi-targeted TKIs in NSCLC.

Nutlin-3 enhances sorafenib efficacy in renal cell carcinoma

The renal cell carcinoma (RCC) is one of the top 10 cancers in USA. The renal tumors are highly angiogenic and are resistant to conventional interventions, particularly radiotherapy. The advent of multi-specific tyrosine kinase inhibitor sorafenib has improved the progression-free survival in RCC, but overall survival in recurrent and metastatic RCC is still a concern that has lead to characterization of combinatorial regimens. Hence, we studied the effect of combination of nutlin-3, an MDM2 inhibitor, which increases p53 levels, and sorafenib in RCC. Sorafenib along with nutlin-3 synergistically inhibited the cell survival and enhanced caspase-3 cleavage leading to apoptosis in RCC. Nutlin-3 and sorafenib were more effective in reducing the migration of RCC, in combination than as single agents. Sorafenib and nutlin-3 decreased the phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) and ERK along with inducing p53 activity. The sorafenib and nutlin-3 co-treatment lead to enhanced levels of p53, p-p53, and increase in the levels of p53 pro-apoptotic effector PUMA, Bax, and decrease in the anti-apoptotic Bcl-2 levels. Importantly, our studies revealed that sorafenib alone can activate p53 in a concentration dependent manner. Thus, co-treatment of nutlin-3 with sorafenib leads to increased half-life of p53, which in turn can be activated by sorafenib, to induce downstream pro-apoptotic and anti-proliferative effects. This is the first report showing the synergistic effect of sorafenib and nutlin-3 while providing a strong clinical-translational rationale for further testing of sorafenib and nutlin-3 combinatorial regimen in human RCC.

Molecular classification of nonsmall cell lung cancer using a 4-protein quantitative assay

BACKGROUND

The importance of definitive histological subclassification has increased as drug trials have shown benefit associated with histology in nonsmall-cell lung cancer (NSCLC). The acuity of this problem is further exacerbated by the use of minimally invasive cytology samples. Here we describe the development and validation of a 4-protein classifier that differentiates primary lung adenocarcinomas (AC) from squamous cell carcinomas (SCC).

METHODS

Quantitative immunofluorescence (AQUA) was employed to measure proteins differentially expressed between AC and SCC followed by logistic regression analysis. An objective 4-protein classifier was generated to define likelihood of AC in a training set of 343 patients followed by validation in 2 independent cohorts (n = 197 and n = 235). The assay was then tested on 11 cytology specimens.

RESULTS

Statistical modeling selected thyroid transcription factor 1 (TTF1), CK5, CK13, and epidermal growth factor receptor (EGFR) to generate a weighted classifier and to identify the optimal cutpoint for differentiating AC from SCC. Using the pathologist's final diagnosis as the criterion standard, the molecular test showed a sensitivity of 96% and specificity of 93%. Blinded analysis of the validation sets yielded sensitivity and specificity of 96% and 97%, respectively. Our assay classified the cytology specimens with a specificity of 100% and sensitivity of 87.5%.

CONCLUSIONS

Molecular classification of NSCLC using an objective quantitative test can be highly accurate and could be translated into a diagnostic platform for broad clinical application.

Recent clinical developments and rationale for combining targeted agents in non-small cell lung cancer (NSCLC)

While chemotherapy has been the standard of care for patients with advanced non-small cell lung cancer (NSCLC), efforts have shifted toward evaluating novel targeted agents in an attempt to improve outcome. These targeted agents are directed toward key components in several signalling pathways such as vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), epidermal growth factor receptor (EGFR) and insulin-like growth factor 1 receptor (IGF-IR). There is also increasing interest in using combinations of targeted agents to inhibit more than one pathway; for example, inhibition of VEGFR + EGFR and VEGFR + PDGFR + EGFR. Further investigation is needed to identify the most appropriate combinations of these targeted agents in select patient subgroups, and to define optimal treatment doses to thereby achieve the best therapeutic index. This review outlines the rationale for combining targeted agents for the treatment of advanced NSCLC.

Lymphangiogenesis in post-natal tissue remodeling: lymphatic endothelial cell connection with its environment

The main physiological function of the lymphatic vasculature is to maintain tissue fluid homeostasis. Lymphangiogenesis or de novo lymphatic formation is closely associated with tissue inflammation in adults (i.e. wound healing, allograft rejection, tumor metastasis). Until recently, research on lymphangiogenesis focused mainly on growth factor/growth factor-receptor pathways governing this process. One of the lymphatic vessel features is the incomplete or absence of basement membrane. This close association of endothelial cells with the underlying interstitial matrix suggests that cell-matrix interactions play an important role in lymphangiogenesis and lymphatic functions. However, the exploration of interaction between extracellular matrix (ECM) components and lymphatic endothelial cells is in its infancy. Herein, we describe ECM-cell and cell-cell interactions on lymphatic system function and their modification occurring in pathologies including cancer metastasis.

HIF, hypoxia and the role of angiogenesis in non-small cell lung cancer

IMPORTANCE OF THE FIELD

The role of angiogenesis in the initiation and progression of NSCLC and the molecular alterations leading to the growth of tumor vasculature are areas of great interest and recent therapeutic success.

AREAS COVERED IN THIS REVIEW

VEGF and its receptors play critical roles in the development of tumor vasculature and can be targeted by agents such as bevacizumab in the treatment of NSCLC. Furthermore, tumor hypoxia and the expression of the hypoxia-inducible factor (HIF) family of proteins are also linked to poorer survival in these patients. Recent studies using genetically engineered mouse models expressing stabilized HIF validate the importance of HIF in the evolution of NSCLC and demonstrate genetically that HIF is involved in NSCLC.

WHAT THE READER WILL GAIN

An overview of the key pathways and mediators of tumor angiogenesis, their relevance to the pathogenesis of NSCLC, and an update on the current status of angiogenesis inhibitors in NSCLC.

TAKE HOME MESSAGE

Angiogenesis is a key mediator of NSCLC progression. Several antiangiogenic strategies are in clinical use and under development. While candidate predictive biomarkers of response to antiangiogenic therapy exist, they await independent and prospective validation.

Update on anti-angiogenic therapy in non-small cell lung cancer: Are we making progress?

Non-small cell lung cancer (NSCLC) remains a leading cause of death worldwide among patients diagnosed with malignancy. Despite new chemotherapy regimens and new cytotoxic combinations investigated in multiple clinical trials in recent years, no significant improvement in the prognosis of patients with lung cancer was achieved. The five-year survival rate for all patients diagnosed with NSCLC is about 15%, only 5% better than that of more than 40 years ago. New therapeutic approaches that target various different aspects of tumor progression and metastasis are of particular interest in to NSCLC patients. Drugs that block tumor vascularization (angiogenesis) or interfere with the activity of growth factor receptors and molecular pathways that are triggered by activation of these receptors are already used in clinical practice. In this review we will briefly discuss briefly the basic mechanisms of lung cancer angiogenesis, rationale for using drugs that block this process and present the most current recent data on their clinical efficacy.

Sorafenib in combination with erlotinib or with gemcitabine in elderly patients with advanced non-small-cell lung cancer: a randomized phase II study

BACKGROUND

Sorafenib is a small-molecule multitargeted kinase inhibitor that blocks the activation of C-RAF, B-RAF, c-KIT, FLT-3, RET, vascular endothelial growth factor receptor 2 (VEGFR-2), VEGFR-3 and platelet-derived growth factor receptor β. The aim of this multicenter, randomized phase II study was to evaluate clinical activity and safety of sorafenib in combination with erlotinib or gemcitabine in unselected untreated elderly patients with non-small-cell lung cancer (NSCLC).

METHODS

The trial was designed to select the most promising sorafenib-containing combination in previously untreated elderly (≥70 years) stage IIIB or IV NSCLC patients, with performance status of zero to two. Patients were randomly assigned to one of the following combinations: gemcitabine, 1200 mg/m(2) days 1 and 8, every 21 days, for a maximum of six cycles, plus sorafenib, 800 mg/day, until disease progression or unacceptable toxicity (arm 1); or erlotinib, 150 mg/day, plus sorafenib, 800 mg/day, until disease progression or unacceptable toxicity (arm 2). A selection design was applied with 1-year survival rate as the primary end point of the study, requiring 58 patients.

RESULTS

Sixty patients were randomly allocated to the study (31 patients in arm 1 and 29 patients in arm 2). After a median follow-up of 15 months, 10 patients [32%, 95% confidence interval (CI) 16% to 49%] in arm 1 and 13 patients (45%, 95% CI 27% to 63%) in arm 2 were alive at 1 year. Median overall survival was 6.6 and 12.6 months in arm 1 and arm 2, respectively. Observed toxic effects were consistent with the expected drug profiles.

CONCLUSIONS

The combination of erlotinib and sorafenib was feasible in elderly patients with advanced NSCLC and was associated with a higher 1-year survival rate than the other arm. According to the selection design, this combination warrants further investigation in phase III trials.

Tyrosine kinase inhibitors with antiangiogenic properties for the treatment of non-small cell lung cancer

IMPORTANCE OF THE FIELD

The 5-year survival rate in NSCLC remains < 15% in spite of new chemotherapeutic regimens and targeted therapies. Tyrosine kinase inhibitors (TKIs) with antiangiogenic properties show promise as a new therapeutic approach for NSCLC in recent studies.

AREAS COVERED IN THIS REVIEW

This article reviews significant preclinical and clinical studies related to TKI therapy. Many drugs that target tyrosine kinases involved in tumor angiogenesis have recently been developed. Results of preclinical experiments and clinical trials for NSCLC are quite promising. However, response rates are low and the duration of therapeutic response is short. Mechanisms of resistance may reduce the efficacy of TKI therapy, and biomarkers of response are needed to select patients who are more likely to benefit from the therapy. Studies in mice have shown that antiangiogenic TKIs may increase metastasis, although no clear clinical evidence supports these results.

WHAT THE READER WILL GAIN

An understanding of the mechanisms of action, clinical trial results, biomarkers of response, adverse effects and possible mechanisms of resistance associated with novel TKI therapy in NSCLC.

TAKE HOME MESSAGE

More preclinical and clinical research on the efficacy of TKIs in treating NSCLC is needed, but present results offer great hope for patients.

Inhibitory effects of a chimeric anti-VEGFR-2 Fab antibody on tumor growth and angiogenesis in an orthotopic xenograft mouse model of hepatocellular carcinoma

AIM: To investigate the inhibitory effects of a mouse chimeric anti-VEGFR-2 Fab antibody on tumor growth and angiogenesis in an orthotopic xenograft mouse model of hepatocellular carcinoma.

METHODS: The antigen-binding activity of cFab antibody was assessed by ELISA. An orthotopic xenograft mouse model of hepatocellular carcinoma was created by direct injection of H22 cells into the liver parenchyma of ICR mice. Twenty-four ICR mice bearing orthotopic HCC were divided into two groups: control group (treated with normal saline) and cFab group (treated with cFab antibody). After the treatment, tumor weight and mouse survival time were compared between the two groups. Histological changes and microvessel density (MVD) in tumors were also evaluated.

RESULTS: The chimeric anti-VEGFR-2 Fab antibody exhibited a strong binding activity to VEGFR-2. Tumor size in the cFab group was significantly decreased compared with the control group (313.9 mm³ ± 41.9 mm³vs 635.4 mm³ ± 70.1 mm³, P < 0.05); and the mice of the cFab group had a significantly longer survival time (20.0 d vs 13.0 d, Long-rank test χ² = 4.611, P = 0.032). The MVD in the cFab group was also significantly lower than that in the control group (34.48 ± 1.39 vs 9.56 ± 1.26,P < 0.05).

CONCLUSION: The chimeric anti-VEGFR-2 Fab antibody can inhibit tumor growth in an orthotopic xenograft mouse model of hepatocellular carcinoma possibly by inhibiting tumor angiogenesis.

SU11248 (sunitinib) directly inhibits the activity of mammalian 5'-AMP-activated protein kinase (AMPK)

AMPK has been termed the fuel sensor of mammalian cells because it directly responds to the depletion of the fuel molecule ATP. In previous work, we found that AMPK is strongly activated by tumor-like hypoxia and glucose deprivation, independently of the oxygen response system associated with HIF-1. We also observed high levels of AMPK activity in tumor cells in vivo, using different model tumors. These findings suggested the hypothesis that modulation of AMPK activity could have therapeutic value for the treatment of solid tumors. To investigate this hypothesis, we have been conducting a SAR study of potential small-molecule modulators of AMPK activity. Here we report that the chemotherapeutic drug SU11248 (sunitinib) is at least as potent an inhibitor of AMPK as compound C, which is a commonly used experimental direct inhibitor of the enzyme. We also provide a computational model of the binding pose of SU11248 to an AMPKα subunit, which suggests a structural basis for the affinity of the drug for the ATP site of the catalytic domain. The ability of SU11248 to inhibit AMPK has potential clinical significance--there may be populations of SU11248-treated patients in which AMPK activity is inhibited in normal as well as in tumor tissue.

Sorafenib induces growth arrest and apoptosis of human glioblastoma cells through the dephosphorylation of signal transducers and activators of transcription 3

Glioblastoma is the most common type of primary brain tumor and is rapidly progressive with few treatment options. Here, we report that sorafenib (< or =10 micromol/L) inhibited cell proliferation and induced apoptosis in two established cell lines (U87 and U251) and two primary cultures (PBT015 and PBT022) from human glioblastomas. The effects of sorafenib on these tumor cells were associated with inhibiting phosphorylated signal transducers and activators of transcription 3 (STAT3; Tyr705). Expression of a constitutively activated STAT3 mutant partially blocked the effects of sorafenib, consistent with a role for STAT3 inhibition in the response to sorafenib. Phosphorylated Janus-activated kinase (JAK)1 was inhibited in U87 and U251 cells, whereas phosphorylated JAK2 was inhibited in primary cultures. Sodium vanadate, a general inhibitor of protein tyrosine phosphatases, blocked the inhibition of phosphorylation of STAT3 (Tyr705) induced by sorafenib. These data indicate that the inhibition of STAT3 activity by sorafenib involves both the inhibition of upstream kinases (JAK1 and JAK2) of STAT3 and increased phosphatase activity. Phosphorylation of AKT was also reduced by sorafenib. In contrast, mitogen-activated protein kinases were not consistently inhibited by sorafenib in these cells. Two key cyclins (D and E) and the antiapoptotic protein Mcl-1 were downregulated by sorafenib in both cell lines and primary cultures. Our data suggest that inhibition of STAT3 signaling by sorafenib contributes to growth arrest and induction of apoptosis in glioblastoma cells. These findings provide a rationale for potential treatment of malignant gliomas with sorafenib. Mol Cancer Ther; 9(4); 953-62. (c)2010 AACR.

Interleukin-6 in bone metastasis and cancer progression

The bone and bone marrow are among the most frequent sites of cancer metastasis. It is estimated that 350,000 patients die with bone metastases annually in the United States. The ability of tumor cells to colonize the bone marrow and invade the bone is the result of close interactions between tumor cells and the bone marrow microenvironment. In this article, we review the contribution of interleukin-6 (IL-6) produced in the bone marrow microenvironment to bone metastasis. This cytokine has a strong pro-tumorigenic activity due to its multiple effects on bone metabolism, tumor cell proliferation and survival, angiogenesis, and inflammation. These effects are mediated by several signaling pathways, in particular the Janus kinase/signal transducer and transcription activator (JAK/STAT-3), Ras/mitogen activated protein kinase (MAPK), and phosphoinositol-3 kinase (PI3K)-protein kinase B/Akt (PkB/Akt), which are activated by IL-6 and amplified in the presence of soluble IL-6 receptor (sIL-6R). Supporting the role of IL-6 in human cancer is the observation of elevated serum levels of IL-6 and sIL-6R in patients with bone metastasis and their association with a poor clinical outcome. Over the last decade several large (monoclonal antibodies) and small (inhibitors of IL-6 mediated signaling) molecules that inhibit IL-6 activity in preclinical models have been developed. Several of these inhibitors are now undergoing phases I and II clinical trials, which will determine their inclusion in the list of effective targeted agents in the fight against cancer.