Biomarkers of clinical responsiveness in brain tumor patients : progress and potential

Gliomas are the most common primary brain tumors in adults. Anaplastic astrocytoma and glioblastoma multiforme represent malignant astrocytomas, which are the most common type of malignant gliomas. Despite research efforts in cancer therapy, the prognosis of patients with malignant gliomas remains poor. Research efforts in recent years have focused on investigating the cellular, molecular, and genetic pathways involved in the progression of malignant gliomas. As a result, biomarkers have emerged as diagnostic, predictive, and prognostic tools that have the potential to transform the field of brain tumor diagnostics. An increased understanding of the important molecular pathways that have been implicated in the progression of malignant gliomas has led to the identification of potential diagnostic, prognostic, and predictive biomarkers, some bearing clinical implications for targeted therapy. Some of the most promising biomarkers to date include loss of chromosomes 1p/19q in oligodendrogliomas and expression of O-6-methylguanine-DNA methyltransferase (MGMT) or epidermal growth factor receptor (EGFR) status in glioblastomas. Other promising biomarkers in glioma research include glial fibrillary acidic protein, galectins, Kir potassium channel proteins, angiogenesis, and apoptosis pathway markers. Research into the clinical relevance and applicability of such biomarkers has the potential to revolutionize our approach to the diagnosis and treatment of patients with malignant gliomas.     

Insulin‐like growth factor axis targeting in cancer and tumour angiogenesis – the missing link

Numerous molecular players in the process of tumour angiogenesis have been shown to offer potential for therapeutic targeting. Initially denoted to be involved in malignant transformation and tumour progression, the insulin‐like growth factor (IGF) signalling axis has been subject to therapeutic interference, albeit with limited clinical success. More recently, IGFs and their receptors have received attention for their contribution to tumour angiogenesis, which offers novel therapeutic opportunities. Here we review the contribution of this signalling axis to tumour angiogenesis, the mechanisms of resistance to therapy and the interplay with other pro‐angiogenic pathways, to offer insight in the renewed interest in the application of IGF axis targeting agents in anti‐cancer combination therapies.     

Anti‐angiogenic therapy: Adapting strategies to overcome resistant tumors

Healthy cells, as well as benign and malignant tumors, depend upon the body's blood supply to bring in oxygen and nutrients and carry away waste products. Using this property against tumors, anti‐angiogenic therapy targets the tumor vasculature with the aim of starving the tumor, and has demonstrated exceptional clinical efficacy against a number of tumors. This review discusses the current state of knowledge regarding anti‐angiogenic therapies presently available to patients, and garners from both preclinical and clinical literature the benefits and side effects associated with anti‐angiogenic therapies, the unfortunate mechanisms of acquired resistance to these novel therapeutics, and highlights promising next generation anti‐angiogenics that may overcome the limitations encountered with first generation therapies. J. Cell. Biochem. 111: 543–553, 2010. © 2010 Wiley‐Liss, Inc.     

Anti‐inflammatory effects of doxepin hydrochloride against LPS‐induced C6‐glioma cell inflammatory reaction by PI3K‐mediated Akt signaling

Recent studies have shown that tricyclic antidepressants (TCAs) may have anti‐inflammatory and anticonvulsant effects in addition to its antidepressant effects. So far, the nonantidepressant effects of TCAs and their molecular pharmacological mechanisms remain completely unclear. Chronic inflammation in the brain parenchyma may be related to the pathogenesis and progression of various neurodegenerative diseases. As a common antidepressant and anti‐insomnia drug, doxepin also may be a potential anti‐inflammatory and anticonvulsant drug, so the study on the anti‐inflammatory protective effect of doxepin and its molecular mechanism has become a very important issue in pharmacology and clinical medicine. Further elucidating the anti‐inflammatory and neuroprotective effects of doxepin and its molecular mechanism may provide the important theoretical and clinical basis for the prevention and treatment of neurodegenerative disease. This study was designed to understand the glio‐protective mechanism of doxepin against the inflammatory damage induced by lipopolysaccharide (LPS) exposure in C6‐glioma cells. We found the treatment of C6‐glioma cells with LPS results in deleterious effects, including the augmentation of inflammatory cytokine levels (tumor necrosis factor‐α, interleukin‐1β), and suppresses the Akt phosphorylation. Furthermore, our outcomes demonstrated that doxepin was able to suppress these effects induced by LPS, through activation of the phosphatidylinositol‐3‐kinase‐mediated protein kinase B (Akt) pathway. To sum up, these results highlight the potential role of doxepin against neuroinflammatory‐related disease in the brain.     

Low‐dose angiostatic tyrosine kinase inhibitors improve photodynamic therapy for cancer: lack of vascular normalization

Photodynamic therapy (PDT) is an effective clinical treatment for a number of different cancers. PDT can induce hypoxia and inflammation, pro‐angiogenic side effects, which may counteract its angio‐occlusive mechanism. The combination of PDT with anti‐angiogenic drugs offers a possibility for improved anti‐tumour outcome. We used two tumour models to test the effects of the clinically approved angiostatic tyrosine kinase inhibitors sunitinib, sorafenib and axitinib in combination with PDT, and compared these results with the effects of bevacizumab, the anti‐VEGF antibody, for the improvement of PDT. Best results were obtained from the combination of PDT and low‐dose axitinib or sorafenib. Molecular analysis by PCR revealed that PDT in combination with axitinib suppressed VEGFR‐2 expression in tumour vasculature. Treatment with bevacizumab, although effective as monotherapy, did not improve PDT outcome. In order to test for tumour vessel normalization effects, axitinib was also applied prior to PDT. The absence of improved PDT outcome in these experiments, as well as the lack of increased oxygenation in axitinib‐treated tumours, suggests that vascular normalization did not occur. The current data imply that there is a future for certain anti‐angiogenic agents to further improve the efficacy of photodynamic anti‐cancer therapy.     

Metformin's antitumour and anti‐angiogenic activities are mediated by skewing macrophage polarization

Beneficial effects of metformin on cancer risk and mortality have been proved by epidemiological and clinical studies, thus attracting research interest in elucidating the underlying mechanisms. Recently, tumour‐associated macrophages (TAMs) appeared to be implicated in metformin‐induced antitumour activities. However, how metformin inhibits TAMs‐induced tumour progression remains ill‐defined. Here, we report that metformin‐induced antitumour and anti‐angiogenic activities were not or only partially contributed by its direct inhibition of functions of tumour and endothelial cells. By skewing TAM polarization from M2‐ to M1‐like phenotype, metformin inhibited both tumour growth and angiogenesis. Depletion of TAMs by clodronate liposomes eliminated M2‐TAMs‐induced angiogenic promotion, while also abrogating M1‐TAMs‐mediated anti‐angiogenesis, thus promoting angiogenesis in tumours from metformin treatment mice. Further in vitro experiments using TAMs‐conditioned medium and a coculture system were performed, which demonstrated an inhibitory effect of metformin on endothelial sprouting and tumour cell proliferation promoted by M2‐polarized RAW264.7 macrophages. Based on these results, metformin‐induced inhibition of tumour growth and angiogenesis is greatly contributed by skewing of TAMs polarization in microenvironment, thus offering therapeutic opportunities for metformin in cancer treatment.     

Optimized monoclonal antibody treatment against ELTD1 for GBM in a G55 xenograft mouse model

Glioblastoma is an aggressive brain tumour found in adults, and the therapeutic approaches available have not significantly increased patient survival. Recently, we discovered that ELTD1, an angiogenic biomarker, is highly expressed in human gliomas. Polyclonal anti‐ELTD1 treatments were effective in glioma pre‐clinical models, however, pAb binding is potentially promiscuous. Therefore, the aim of this study was to determine the effects of an optimized monoclonal anti‐ELTD1 treatment in G55 xenograft glioma models. MRI was used to assess the effects of the treatments on animal survival, tumour volumes, perfusion rates and binding specificity. Immunohistochemistry and histology were conducted to confirm and characterize microvessel density and Notch1 levels, and to locate the molecular probes. RNA‐sequencing was used to analyse the effects of the mAb treatment. Our monoclonal anti‐ELTD1 treatment significantly increased animal survival, reduced tumour volumes, normalized the vasculature and showed higher binding specificity within the tumour compared with both control‐ and polyclonal‐treated mice. Notch1 positivity staining and RNA‐seq results suggested that ELTD1 has the ability to interact with and interrupt Notch1 signalling. Although little is known about ELTD1, particularly about its ligand and pathways, our data suggest that our monoclonal anti‐ELTD1 antibody is a promising anti‐angiogenic therapeutic in glioblastomas.     

Killing cancer with platycodin D through multiple mechanisms

Cancer is a multi‐faceted disease comprised of a combination of genetic, epigenetic, metabolic and signalling aberrations which severely disrupt the normal homoeostasis of cell growth and death. Rational developments of highly selective drugs which specifically block only one of the signalling pathways have been associated with limited therapeutic success. Multi‐targeted prevention of cancer has emerged as a new paradigm for effective anti‐cancer treatment. Platycodin D, a triterpenoid saponin, is one the major active components of the roots of Platycodon grandiflorum and possesses multiple biological and pharmacological properties including, anti‐nociceptive, anti‐atherosclerosis, antiviral, anti‐inflammatory, anti‐obesity, immunoregulatory, hepatoprotective and anti‐tumour activities. Recently, the anti‐cancer activity of platycodin D has been extensively studied. The purpose of this review was to give our perspectives on the current status of platycodin D and discuss its anti‐cancer activity and molecular mechanisms which may help the further design and conduct of pre‐clinical and clinical trials to develop it successfully into a potential lead drug for oncological therapy. Platycodin D has been shown to fight cancer by inducing apoptosis, cell cycle arrest, and autophagy and inhibiting angiogenesis, invasion and metastasis by targeting multiple signalling pathways which are frequently deregulated in cancers suggesting that this multi‐target activity rather than a single effect may play an important role in developing platycodin D into potential anti‐cancer drug.     

Integrative analysis from multi‐centre studies identifies a function‐derived personalized multi‐gene signature of outcome in colorectal cancer

Colorectal cancer (CRC) is highly heterogeneous leading to variable prognosis and treatment responses. Therefore, it is necessary to explore novel personalized and reproducible prognostic signatures to aid clinical decision‐making. The present study combined large‐scale gene expression profiles and clinical data of 1828 patients with CRC from multi‐centre studies and identified a personalized gene prognostic signature consisting of 46 unique genes (called function‐derived personalized gene signature [FunPGS]) from an integrated statistics and function‐derived perspective. In the meta‐training and multiple independent validation cohorts, the FunPGS effectively discriminated patients with CRC with significantly different prognosis at the individual level and remained as an independent factor upon adjusting for clinical covariates in multivariate analysis. Furthermore, the FunPGS demonstrated superior performance for risk stratification with respect to other recently reported signatures and clinical factors. The complementary value of the molecular signature and clinical factors was further explored, and it was observed that the composite signature called IMCPS greatly improved the predictive performance of survival estimation relative to molecular signatures or clinical factors alone. With further prospective validation in clinical trials, the FunPGS may become a promising and powerful personalized prognostic tool for stratifying patients with CRC in order to achieve an optimal systemic therapy.     

Tumour biomarkers—Tracing the molecular function and clinical implication

In recent years, with the increase in cancer mortality caused by metastasis, and with the development of individualized and precise medical treatment, early diagnosis with precision becomes the key to decrease the death rate. Since detecting tumour biomarkers in body fluids is the most non‐invasive way to identify the status of tumour development, it has been widely investigated for the usage in clinic. These biomarkers include different expression or mutation in microRNAs (miRNAs), circulating tumour DNAs (ctDNAs), proteins, exosomes and circulating tumour cells (CTCs). In the present article, we summarized and discussed some updated research on these biomarkers. We overviewed their biological functions and evaluated their multiple roles in human and small animal clinical treatment, including diagnosis of cancers, classification of cancers, prognostic and predictive values for therapy response, monitors for therapy efficacy, and anti‐cancer therapeutics. Biomarkers including different expression or mutation in miRNAs, ctDNAs, proteins, exosomes and CTCs provide more choice for early diagnosis of tumour detection at early stage before metastasis. Combination detection of these tumour biomarkers may provide higher accuracy at the lowest molecule combination number for tumour early detection. Moreover, tumour biomarkers can provide valuable suggestions for clinical anti‐cancer treatment and execute monitoring of treatment efficiency.     

Pathway mapping and development of disease‐specific biomarkers: protein‐based network biomarkers

It is known that a disease is rarely a consequence of an abnormality of a single gene, but reflects the interactions of various processes in a complex network. Annotated molecular networks offer new opportunities to understand diseases within a systems biology framework and provide an excellent substrate for network‐based identification of biomarkers. The network biomarkers and dynamic network biomarkers (DNBs) represent new types of biomarkers with protein–protein or gene–gene interactions that can be monitored and evaluated at different stages and time‐points during development of disease. Clinical bioinformatics as a new way to combine clinical measurements and signs with human tissue‐generated bioinformatics is crucial to translate biomarkers into clinical application, validate the disease specificity, and understand the role of biomarkers in clinical settings. In this article, the recent advances and developments on network biomarkers and DNBs are comprehensively reviewed. How network biomarkers help a better understanding of molecular mechanism of diseases, the advantages and constraints of network biomarkers for clinical application, clinical bioinformatics as a bridge to the development of diseases‐specific, stage‐specific, severity‐specific and therapy predictive biomarkers, and the potentials of network biomarkers are also discussed.     

The β3‐integrin endothelial adhesome regulates microtubule‐dependent cell migration

Integrin β3 is seen as a key anti‐angiogenic target for cancer treatment due to its expression on neovasculature, but the role it plays in the process is complex; whether it is pro‐ or anti‐angiogenic depends on the context in which it is expressed. To understand precisely β3's role in regulating integrin adhesion complexes in endothelial cells, we characterised, by mass spectrometry, the β3‐dependent adhesome. We show that depletion of β3‐integrin in this cell type leads to changes in microtubule behaviour that control cell migration. β3‐integrin regulates microtubule stability in endothelial cells through Rcc2/Anxa2‐driven control of active Rac1 localisation. Our findings reveal that angiogenic processes, both in vitro and in vivo, are more sensitive to microtubule targeting agents when β3‐integrin levels are reduced.     

The impact of age on oncogenic potential: tumor‐initiating cells and the brain microenvironment

Paradoxically, aging leads to both decreased regenerative capacity in the brain and an increased risk of tumorigenesis, particularly the most common adult‐onset brain tumor, glioma. A shared factor contributing to both phenomena is thought to be age‐related alterations in neural progenitor cells (NPCs), which function normally to produce new neurons and glia, but are also considered likely cells of origin for malignant glioma. Upon oncogenic transformation, cells acquire characteristics known as the hallmarks of cancer, including unlimited replication, altered responses to growth and anti‐growth factors, increased capacity for angiogenesis, potential for invasion, genetic instability, apoptotic evasion, escape from immune surveillance, and an adaptive metabolic phenotype. The precise molecular pathogenesis and temporal acquisition of these malignant characteristics is largely a mystery. Recent studies characterizing NPCs during normal aging, however, have begun to elucidate mechanisms underlying the age‐associated increase in their malignant potential. Aging cells are dependent upon multiple compensatory pathways to maintain cell cycle control, normal niche interactions, genetic stability, programmed cell death, and oxidative metabolism. A few multi‐functional proteins act as ‘critical nodes’ in the coordination of these various cellular activities, although both intracellular signaling and elements within the brain environment are critical to maintaining a balance between senescence and tumorigenesis. Here, we provide an overview of recent progress in our understanding of how mechanisms underlying cellular aging inform on glioma pathogenesis and malignancy.     

Rapid anti‐depressant‐like effects of ketamine and other candidates: Molecular and cellular mechanisms

Major depressive disorder takes at least 3 weeks for clinical anti‐depressants, such as serotonin selective reuptake inhibitors, to take effect, and only one‐third of patients remit. Ketamine, a kind of anaesthetic, can alleviate symptoms of major depressive disorder patients in a short time and is reported to be effective to treatment‐resistant depression patients. The rapid and strong anti‐depressant‐like effects of ketamine cause wide concern. In addition to ketamine, caloric restriction and sleep deprivation also elicit similar rapid anti‐depressant‐like effects. However, mechanisms about the rapid anti‐depressant‐like effects remain unclear. Elucidating the mechanisms of rapid anti‐depressant effects is the key to finding new therapeutic targets and developing therapeutic patterns. Therefore, in this review we summarize potential molecular and cellular mechanisms of rapid anti‐depressant‐like effects based on the pre‐clinical and clinical evidence, trying to provide new insight into future therapy.     

Targeted nitric oxide delivery preferentially induces glioma cell chemosensitivity via altered p53 and O6‐Methylguanine‐DNA Methyltransferase activity

Glioblastoma multiforme is the most common malignant central nervous system tumor, and also among the most difficult to treat due to a lack of response to chemotherapeutics. New methods of countering the mechanisms that confer chemoresistance to malignant gliomas could lead to significant advances in the quest to identify novel drug combinations or targeted drug delivery systems for cancer therapy. In this study, we investigate the use of a targeted nitric oxide (NO) donor as a pretreatment to sensitize glioma cells to chemotherapy. The protein chlorotoxin (CTX) has been shown to preferentially target glioma cells, and we have developed CTX–NO, a glioma‐specific, NO‐donating CTX derivative. Pretreatment of cells with CTX–NO followed by 48‐h exposure to either carmustine (BCNU) or temozolomide (TMZ), both common chemotherapeutics used in glioma treatment, resulted in increased efficacy of both therapeutics. After CTX–NO exposure, both T98G and U‐87MG human malignant glioma cells show increased sensitivity to BCNU and TMZ. Further investigation revealed that the consequences of this combination therapy was a reduction in active levels of the cytoprotective enzyme MGMT and altered p53 activity, both of which are essential in DNA repair and tumor cell resistance to chemotherapy. The combination of CTX–NO and chemotherapeutics also led to decreased cell invasion. These studies indicate that this targeted NO donor could be an invaluable tool in the development of novel approaches to treat cancer. Biotechnol. Bioeng. 2013; 110: 1211–1220. © 2012 Wiley Periodicals, Inc.     

3,4‐dimethoxystilbene,a resveratrol derivative with anti‐angiogenic effect,induces both macroautophagy and apoptosis in endothelial cells

Angiogenesis plays an important role in many pathological processes. Identification of novel anti‐angiogenic agents will provide new insights into the mechanisms for angiogenesis as well as potential lead compounds for developing new drugs. In the present study, a series of resveratrol methylated derivatives have been synthesized and screened. We found trans‐3,4‐dimethoxystilbene (3,4‐DMS) with the fullest potential to develop as an anti‐angiogenic agent. In vitro and in vivo analyses suggested that 3,4‐DMS could effectively inhibit endothelial cell proliferation, migration, tube formation, and endogenous neovascularization. Our results showed that 3,4‐DMS exerted its anti‐angiogenic effect likely through induction of endothelial cell apoptosis via a pathway involving p53, Bax, cytochrome c, and caspase proteases. Moreover, 3,4‐DMS also induced macroautophagy in endothelial cells through activation of AMPK and the downstream inhibition of mTOR signaling pathway. Further studies indicated that intracellular calcium ([Ca²⁺]_i) might bridge the 3,4‐DMS‐induced apoptosis and macroautophagy through modulating reactive oxygen species (ROS) levels in endothelial cells. Combination of 3,4‐DMS with inhibitor of autophagy, such as 3‐methyladenine (3‐MA) and autophagy‐related gene (ATG) 5 small interfering RNA (siRNA), potentiated the pro‐apoptotic and anti‐angiogenic effects of 3,4‐DMS. Our study provides a novel angiogenic inhibitor and a useful tool in exploring the molecular mechanisms for the crosstalk between apoptosis and macroautophagy in endothelial cells. 3,4‐DMS could be served as a potential lead compound for developing a class of new drugs targeting angiogenesis‐related diseases. J. Cell. Biochem. 114: 697–707, 2013. © 2012 Wiley Periodicals, Inc.     

Synergy between anti‐CCL2 and docetaxel as determined by DW‐MRI in a metastatic bone cancer model

Metastatic prostate cancer continues to be the second leading cause of cancer death in American men with an estimated 28,660 deaths in 2008. Recently, monocyte chemoattractant protein‐1 (MCP‐1, CCL2) has been identified as an important factor in the regulation of prostate metastasis. CCL2, shown to attract macrophages to the tumor site, has a direct promotional effect on tumor cell proliferation, migration, and survival. Previous studies have shown that anti‐CCL2 antibodies given in combination with docetaxel were able to induce tumor regression in a pre‐clinical prostate cancer model. A limitation for evaluating new treatments for metastatic prostate cancer to bone is the inability of imaging to objectively assess response to treatment. Diffusion‐weighted MRI (DW‐MRI) assesses response to anticancer therapies by quantifying the random (i.e., Brownian) motion of water molecules within the tumor mass, thus identifying cells undergoing apoptosis. We sought to measure the treatment response of prostate cancer in an osseous site to docetaxel, an anti‐CCL2 agent, and combination treatments using DW‐MRI. Measurements of tumor apparent diffusion coefficient (ADC) values were accomplished over time during a 14‐day treatment period and compared to response as measured by bioluminescence imaging and survival studies. The diffusion data provided early predictive evidence of the most effective therapy, with survival data results correlating with the DW‐MRI findings. DW‐MRI is under active investigation in the pre‐clinical and clinical settings to provide a sensitive and quantifiable means for early assessment of cancer treatment outcome. J. Cell. Biochem. 107: 58–64, 2009. © 2009 Wiley‐Liss, Inc.