EGFR overexpression and radiation response in glioblastoma multiforme

Probing phosphorylation events in biological membranes: The transducer function

The extracellular environment is sensed by receptors in the plasma membrane. Some of these receptors initiate cytoplasmic signaling cascades involving phosphorylation: the addition of a phosphate group to a specific amino acid, such as tyrosine, in a protein. Receptor Tyrosine Kinases (RTKs) are one large class of membrane receptors that can directly initiate signaling cascades through their intracellular kinase domains, which both catalyze tyrosine phosphorylation and get phosphorylated. In the first step of signaling, the ligands stabilize phosphorylation-competent RTK dimers and oligomers, which leads to the phosphorylation of specific tyrosine residues in the activation loop of the kinases. Here we discuss quantitative measurements of tyrosine phosphorylation efficiencies for RTKs, described by the "transducer function". The transducer function links the phosphorylation (the response) and the binding of the activating ligand to the receptor (the stimulus). We overview a methodology that allows such measurements in direct response to ligand binding. We discuss experiments which demonstrate that EGF is a partial agonist, and that two tyrosines in the intracellular domain of EGFR, Y1068 and Y1173, are differentially phosphorylated in the EGF-bound EGFR dimers.

An Overview of EGFR Mechanisms and Their Implications in Targeted Therapies for Glioblastoma

Despite all of the progress in understanding its molecular biology and pathogenesis, glioblastoma (GBM) is one of the most aggressive types of cancers, and without an efficient treatment modality at the moment, it remains largely incurable. Nowadays, one of the most frequently studied molecules with important implications in the pathogenesis of the classical subtype of GBM is the epidermal growth factor receptor (EGFR). Although many clinical trials aiming to study EGFR targeted therapies have been performed, none of them have reported promising clinical results when used in glioma patients. The resistance of GBM to these therapies was proven to be both acquired and innate, and it seems to be influenced by a cumulus of factors such as ineffective blood-brain barrier penetration, mutations, heterogeneity and compensatory signaling pathways. Recently, it was shown that EGFR possesses kinase-independent (KID) pro-survival functions in cancer cells. It seems imperative to understand how the EGFR signaling pathways function and how they interconnect with other pathways. Furthermore, it is important to identify the mechanisms of drug resistance and to develop better tailored therapeutic agents.

Transferrin receptor 1 targeted nanomedicine for brain tumor therapy

Achieving effective drug delivery to traverse the blood-brain barrier (BBB) and target tumor cells remains the greatest challenge for brain tumor therapy. Importantly, the overexpressed membrane receptors on the brain endothelial cells, especially transferrin receptor 1 (TfR1), which mediate their ligands/antibodies to overcome the BBB by transcytosis, have been emerging as promising targets for brain tumor therapy. By employing ligands (e.g., transferrin, H-ferritin), antibodies or targeting peptides of TfR1 or aptamers, various functional nano-formulations have been developed in the last decade. These agents showed great potential for the treatment of brain diseases due to their ideal size, high loading capacity, controlled drug release and suitable pharmacokinetics. Herein, we summarize the latest advances on TfR1-targeted nanomedicine for brain tumor therapy. Moreover, we also discuss the strategies of improving stability, targeting ability and accumulation of nano-formulations in brain tumors for better outcomes. In this review, we hope to provide inspiration for the rational design of TfR1-targeted nanomedicine against brain tumors.

Forecasting Molecular Features in IDH-Wildtype Gliomas: The State of the Art of Radiomics Applied to Neurosurgery

BACKGROUND

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, marks a step forward the future diagnostic approach to these neoplasms. Alongside this, radiomics has experienced rapid evolution over the last several years, allowing us to correlate tumor imaging heterogeneity with a wide range of tumor molecular and subcellular features. Radiomics is a translational field focused on decoding conventional imaging data to extrapolate the molecular and prognostic features of tumors such as gliomas. We herein analyze the state-of-the-art of radiomics applied to glioblastoma, with the goal to estimate its current clinical impact and potential perspectives in relation to well-rounded patient management, including the end-of-life stage.

METHODS

A literature review was performed on the PubMed, MEDLINE and Scopus databases using the following search items: "radiomics and glioma", "radiomics and glioblastoma", "radiomics and glioma and IDH", "radiomics and glioma and TERT promoter", "radiomics and glioma and EGFR", "radiomics and glioma and chromosome".

RESULTS

A total of 719 articles were screened. Further quantitative and qualitative analysis allowed us to finally include 11 papers. This analysis shows that radiomics is rapidly evolving towards a reliable tool.

CONCLUSIONS

Further studies are necessary to adjust radiomics' potential to the newest molecular requirements pointed out by the 2021 WHO classification of CNS tumors. At a glance, its application in the clinical routine could be beneficial to achieve a timely diagnosis, especially for those patients not eligible for surgery and/or adjuvant therapies but still deserving palliative and supportive care.

Association of dynamic susceptibility contrast- and dynamic contrast-enhanced magnetic resonance imaging parameters with molecular marker status in lower-grade gliomas: A retrospective study

PURPOSE

Molecular marker status is clinically relevant for treatment planning and predicting the prognosis of gliomas. This study aimed to assess whether quantitative imaging parameters from dynamic susceptibility contrast- (DSC-) and dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) can predict the molecular marker status of lower-grade gliomas (LGGs).

MATERIALS AND METHODS

Overall, 132 patients with LGGs who underwent DSC- and DCE-MRI were retrospectively enrolled. Statuses of relevant molecular markers including isocitrate dehydrogenase isoenzyme (IDH), 1p19q codeletion, epidermal growth factor receptor (EGFR), O6-methylguanine-DNA methyltransferase (MGMT), and telomerase reverse transcriptase (TERT) were collected. For each molecular marker, age, tumor diameter and location, and DSC- and DCE-MRI parameters, including the normalized cerebral blood volume (nCBV), volume transfer constant (Ktrans), rate transfer coefficient (Kep), extravascular extracellular volume fraction (Ve), and plasma volume fraction (Vp), were compared. Multivariable logistic regression analyses were performed.

RESULTS

The nCBV was significantly lower in LGGs with IDH mutation (p = .001) and TERT mutation (p = .027) than those without these mutations. Ktrans (p = .034), Ve (p = .023), and Vp (p = .044) values were significantly lower in MGMT methylated LGGs than in MGMT unmethylated LGGs. Perfusion parameters were not significantly associated with EGFR amplification and 1p19q codeletion. Young age (p < .001) and small diameter (p = .001) were significantly associated with IDH mutation. The nCBV was independently associated with IDH status (AUC, 0.817; 95% CI: 0.739-0.894).

CONCLUSIONS

DSC- and DCE-MRI parameters demonstrated correlations with molecular markers of LGGs. Especially, the nCBV can be helpful in predicting the IDH mutation status.

To Investigate Growth Factor Receptor Targets and Generate Cancer Targeting Inhibitors

Receptor tyrosine kinase (RTK) regulates multiple pathways, including Mitogenactivated protein kinases (MAPKs), PI3/AKT, JAK/STAT pathway, etc. which has a significant role in the progression and metastasis of tumor. As RTK activation regulates numerous essential bodily processes, including cell proliferation and division, RTK dysregulation has been identified in many types of cancers. Targeting RTK is a significant challenge in cancer due to the abnormal upregulation and downregulation of RTK receptors subfamily EGFR, FGFR, PDGFR, VEGFR, and HGFR in the progression of cancer, which is governed by multiple RTK receptor signalling pathways and impacts treatment response and disease progression. In this review, an extensive focus has been carried out on the normal and abnormal signalling pathways of EGFR, FGFR, PDGFR, VEGFR, and HGFR and their association with cancer initiation and progression. These are explored as potential therapeutic cancer targets and therefore, the inhibitors were evaluated alone and merged with additional therapies in clinical trials aimed at combating global cancer.

Cerebellar High-Grade Glioma: A Translationally Oriented Review of the Literature

World Health Organization (WHO) grade 4 gliomas of the cerebellum are rare entities whose understanding trails that of their supratentorial counterparts. Like supratentorial high-grade gliomas (sHGG), cerebellar high-grade gliomas (cHGG) preferentially affect males and prognosis is bleak; however, they are more common in a younger population. While current therapy for cerebellar and supratentorial HGG is the same, recent molecular analyses have identified features and subclasses of cerebellar tumors that may merit individualized targeting. One recent series of cHGG included the subclasses of (1) high-grade astrocytoma with piloid features (HGAP, ~31% of tumors); (2) H3K27M diffuse midline glioma (~8%); and (3) isocitrate dehydrogenase (IDH) wildtype glioblastoma (~43%). The latter had an unusually low-frequency of epidermal growth factor receptor (EGFR) and high-frequency of platelet-derived growth factor receptor alpha (PDGFRA) amplification, reflecting a different composition of methylation classes compared to supratentorial IDH-wildtype tumors. These new classifications have begun to reveal insights into the pathogenesis of HGG in the cerebellum and lead toward individualized treatment targeted toward the appropriate subclass of cHGG. Emerging therapeutic strategies include targeting the mitogen-activated protein kinases (MAPK) pathway and PDGFRA, oncolytic virotherapy, and immunotherapy. HGGs of the cerebellum exhibit biological differences compared to sHGG, and improved understanding of their molecular subclasses has the potential to advance treatment.

Small Molecules and Immunotherapy Agents for Enhancing Radiotherapy in Glioblastoma

Glioblastoma (GBM) is an aggressive primary brain tumor that is associated with a poor prognosis and quality of life. The standard of care has changed minimally over the past two decades and currently consists of surgery followed by radiotherapy (RT), concomitant and adjuvant temozolomide, and tumor treating fields (TTF). Factors such as tumor hypoxia and the presence of glioma stem cells contribute to the radioresistant nature of GBM. In this review, we discuss the current treatment modalities, mechanisms of radioresistance, and studies that have evaluated promising radiosensitizers. Specifically, we highlight small molecules and immunotherapy agents that have been studied in conjunction with RT in clinical trials. Recent preclinical studies involving GBM radiosensitizers are also discussed.

Molecular design, synthesis and in vitro biological evaluation of thienopyrimidine-hydroxamic acids as chimeric kinase HDAC inhibitors: a challenging approach to combat cancer

A series of thieno[2,3-d]pyrimidine-based hydroxamic acid hybrids was designed and synthesised as multitarget anti-cancer agents, through incorporating the pharmacophore of EGFR, VEGFR2 into the inhibitory functionality of HDAC6. Three compounds (12c, 15b and 20b) were promising hits, whereas (12c) exhibited potent VEGFR2 inhibition (IC50=185 nM), potent EGFR inhibition (IC50=1.14 µM), and mild HDAC6 inhibition (23% inhibition). Moreover, compound (15c) was the most potent dual inhibitor among all the synthesised compounds, as it exhibited potent EGFR and VEGFR2 inhibition (IC50=19 nM) and (IC50=5.58 µM), respectively. While compounds (20d) and (7c) displayed nanomolar selective kinase inhibition with EGFR IC50= 68 nM and VEGFR2 IC50= 191 nM, respectively. All of the synthesised compounds were screened in vitro for their cytotoxic effect on 60 human NCI tumour cell lines. Additionally, molecular docking studies and ADMET studies were carried out to gain further insight into their binding mode and predict the pharmacokinetic properties of all the synthesised inhibitors.

Afatinib and radiotherapy, with or without temozolomide, in patients with newly diagnosed glioblastoma: results of a phase I trial

Background

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults. Amplification or overexpression of the epidermal growth factor receptor gene, part of the ErbB family, occur in approximately 40% and 60% of patients with GBM, respectively. We present data from a dose-finding study of the ErbB inhibitor afatinib in combination with radiotherapy (RT), with or without temozolomide (TMZ), in patients with GBM.

Methods

This was a phase I, open-label, 3 + 3 dose-escalation trial in patients with newly-diagnosed, histologically-confirmed grade 4 malignant glioma and proven O⁶-methylguanine-DNA methyltransferase gene promoter methylation status. The primary endpoint was the maximum tolerated dose (MTD) of continuous daily afatinib when given in combination with RT, with (regimen M) or without (regimen U) concomitant TMZ treatment.

Results

Fifty-five patients were enrolled; 36 received ≥ 1 dose of trial medication (regimen M, n = 20, regimen U, n = 16). Afatinib was discontinued by all patients during the study. Reasons for afatinib discontinuation (regimen M/U) included disease progression (45%/50%), dose-limiting toxicity (10%/0%), and other adverse events (AEs; 35%/38%). The most frequently reported AEs with either regimen were diarrhea and rash, with no new safety signals identified. The MTD was determined as afatinib 30 mg in combination with daily TMZ and RT, and afatinib 40 mg in combination with RT alone.

Conclusions

This study identified the MTD for afatinib in combination with RT, with and without TMZ, in patients with GBM. Further studies of afatinib in patients with GBM are warranted and should be based on appropriate biomarker-based preselection.

Trial registration

NCT00977431 (first posted September 15, 2009).

Supplementary Information

The online version contains supplementary material available at 10.1007/s11060-021-03877-6.

Clinical and Preclinical Outcomes of Combining Targeted Therapy With Radiotherapy

In the era of precision medicine, radiation medicine is currently focused on the precise delivery of highly conformal radiation treatments. However, the tremendous developments in targeted therapy are yet to fulfill their full promise and arguably have the potential to dramatically enhance the radiation therapeutic ratio. The increased ability to molecularly profile tumors both at diagnosis and at relapse and the co-incident progress in the field of radiogenomics could potentially pave the way for a more personalized approach to radiation treatment in contrast to the current ‘‘one size fits all’’ paradigm. Few clinical trials to date have shown an improved clinical outcome when combining targeted agents with radiation therapy, however, most have failed to show benefit, which is arguably due to limited preclinical data. Several key molecular pathways could theoretically enhance therapeutic effect of radiation when rationally targeted either by directly enhancing tumor cell kill or indirectly through the abscopal effect of radiation when combined with novel immunotherapies. The timing of combining molecular targeted therapy with radiation is also important to determine and could greatly affect the outcome depending on which pathway is being inhibited.

The Hypoxia-Long Noncoding RNA Interaction in Solid Cancers

Hypoxia is one of the representative microenvironment features in cancer and is considered to be associated with the dismal prognosis of patients. Hypoxia-driven cellular pathways are largely regulated by hypoxia-inducible factors (HIFs) and notably exert influence on the hallmarks of cancer, such as stemness, angiogenesis, invasion, metastasis, and the resistance towards apoptotic cell death and therapeutic resistance; therefore, hypoxia has been considered as a potential hurdle for cancer therapy. Growing evidence has demonstrated that long noncoding RNAs (lncRNAs) are dysregulated in cancer and take part in gene regulatory networks owing to their various modes of action through interacting with proteins and microRNAs. In this review, we focus attention on the relationship between hypoxia/HIFs and lncRNAs, in company with the possibility of lncRNAs as candidate molecules for controlling cancer.

Targeting Cullin-RING E3 Ligases for Radiosensitization: From NEDDylation Inhibition to PROTACs

As a dynamic regulator for short-lived protein degradation and turnover, the ubiquitin-proteasome system (UPS) plays important roles in various biological processes, including response to cellular stress, regulation of cell cycle progression, and carcinogenesis. Over the past decade, research on targeting the cullin-RING (really interesting new gene) E3 ligases (CRLs) in the UPS has gained great momentum with the entry of late-phase clinical trials of its novel inhibitors MLN4924 (pevonedistat) and TAS4464. Several preclinical studies have demonstrated the efficacy of MLN4924 as a radiosensitizer, mainly due to its unique cytotoxic properties, including induction of DNA damage response, cell cycle checkpoints dysregulation, and inhibition of NF-κB and mTOR pathways. Recently, the PROteolysis TArgeting Chimeras (PROTACs) technology was developed to recruit the target proteins for CRL-mediated polyubiquitination, overcoming the resistance that develops inevitably with traditional targeted therapies. First-in-class cell-permeable PROTACs against critical radioresistance conferring proteins, including the epidermal growth factor receptor (EGFR), androgen receptor (AR) and estrogen receptor (ER), cyclin-dependent kinases (CDKs), MAP kinase kinase 1 (MEK1), and MEK2, have emerged in the past 5 years. In this review article, we will summarize the most important research findings of targeting CRLs for radiosensitization.

Glioblastoma: Is There Any Blood Biomarker with True Clinical Relevance?

Glioblastoma (GBM) is the most frequent malignant primary brain tumor in adults, characterized by a highly aggressive, inflammatory and angiogenic phenotype. It is a remarkably heterogeneous tumor at several levels, including histopathologically, radiographically and genetically. The 2016 update of the WHO Classification of Tumours of the Central Nervous System highlighted molecular parameters as paramount features for the diagnosis, namely IDH1/2 mutations that distinguish primary and secondary GBM. An ideal biomarker is a molecule that can be detected/quantified through simple non- or minimally invasive methods with the potential to assess cancer risk; promote early diagnosis; increase grading accuracy; and monitor disease evolution and treatment response, as well as fundamentally being restricted to one aspect. Blood-based biomarkers are particularly attractive due to their easy access and have been widely used for various cancer types. A number of serum biomarkers with multiple utilities for glioma have been reported that could classify glioma grades more precisely and provide prognostic value among these patients. At present, screening for gliomas has no clinical relevance. This is because of the low incidence, the lack of sensitive biomarkers in plasma, and the observation that gliomas may develop apparently de novo within few weeks or months. To the best of our knowledge, there is no routine use of a serum biomarker for clinical follow-up. The purpose of this paper is to review the serum biomarkers described in the literature related to glioblastoma and their possible relationship with clinical features.

Quantifying the strength of heterointeractions among receptor tyrosine kinases from different subfamilies: Implications for cell signaling

Receptor tyrosine kinases (RTKs) are single-pass membrane proteins that control vital cell processes such as cell growth, survival, and differentiation. There is a growing body of evidence that RTKs from different subfamilies can interact and that these diverse interactions can have important biological consequences. However, these heterointeractions are often ignored, and their strengths are unknown. In this work, we studied the heterointeractions of nine RTK pairs, epidermal growth factor receptor (EGFR)-EPH receptor A2 (EPHA2), EGFR-vascular endothelial growth factor receptor 2 (VEGFR2), EPHA2-VEGFR2, EPHA2-fibroblast growth factor receptor 1 (FGFR1), EPHA2-FGFR2, EPHA2-FGFR3, VEGFR2-FGFR1, VEGFR2-FGFR2, and VEGFR2-FGFR3, using a FRET-based method. Surprisingly, we found that RTK heterodimerization and homodimerization strengths can be similar, underscoring the significance of RTK heterointeractions in signaling. We discuss how these heterointeractions can contribute to the complexity of RTK signal transduction, and we highlight the utility of quantitative FRET for probing multiple interactions in the plasma membrane.

Receptor Tyrosine Kinases: Principles and Functions in Glioma Invasion

Protein tyrosine kinases are enzymes that are capable of adding a phosphate group to specific tyrosines on target proteins. A receptor tyrosine kinase (RTK) is a tyrosine kinase located at the cellular membrane and is activated by binding of a ligand via its extracellular domain. Protein phosphorylation by kinases is an important mechanism for communicating signals within a cell and regulating cellular activity; furthermore, this mechanism functions as an "on" or "off" switch in many cellular functions. Ninety unique tyrosine kinase genes, including 58 RTKs, were identified in the human genome; the products of these genes regulate cellular proliferation, survival, differentiation, function, and motility. Tyrosine kinases play a critical role in the development and progression of many types of cancer, in addition to their roles as key regulators of normal cellular processes. Recent studies have revealed that RTKs such as epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR), c-Met, Tie, Axl, discoidin domain receptor 1 (DDR1), and erythropoietin-producing human hepatocellular carcinoma (Eph) play a major role in glioma invasion. Herein, we summarize recent advances in understanding the role of RTKs in glioma pathobiology, especially the invasive phenotype, and present the perspective that RTKs are a potential target of glioma therapy.

Inhibition of the Spectraplakin Protein Microtubule Actin Crosslinking Factor 1 Sensitizes Glioblastomas to Radiation

Background

Microtubule actin crosslinking factor 1 (MACF1) is a spectraplakin cytoskeletal crosslinking protein whose function and role in cancer biology has lacked investigation. Recent studies have identified MACF1 as a novel target in glioblastomas expressed in tissue from tumor patient explants but not normal brain tissue and when silenced has an antitumorigenic impact on these tumors. Radiation as a single agent therapy to treat glioblastomas has been used for decades and has done little to improve survival of individuals diagnosed with this disease. However, contemporary clinical radiotherapy protocols have provided evidence that combinatorial radiotherapy approaches confer a therapeutic benefit in glioblastoma patients. In this study MACF1 was investigated as a radiosensitization target in glioblastomas.

Methods

To provide context of MACF1 in glioblastomas, The Cancer Genome Atlas expression analyses were performed in conjunction with genes associated with glioblastoma evolution, while a genetic inhibitory approach, cell migratory assays, and immunofluorescence procedures were used to evaluate responses to MACF1 suppression with radiation. Additionally, expression analyses were conducted to assess co-expression of mTOR signaling pathway regulators and MACF1 in glioblastoma patient samples.

Results

Our amalgamation approach demonstrated that negative regulation of MACF1, which was positively correlated with epidermal growth factor receptor and p70s6k expression, enhanced the sensitivity of glioblastoma cells to radiation as a consequence of reducing glioblastoma cell viability and migration. Mechanistically, the antitumorigenic effects on glioblastoma cell behaviors after radiation and impairing MACF1 function were associated with decreased expression of ribosomal protein S6, a downstream effector of p70s6k.

Conclusion

MACF1 represents a diagnostic marker with target specificity in glioblastomas that can enhance the efficacy of radiation while minimizing normal tissue toxicity. This approach could potentially expand combinatorial radiation strategies for glioblastoma treatments via impairment of translational regulatory processes that contribute to poor patient survival.

Membrane receptor activation mechanisms and transmembrane peptide tools to elucidate them

Single-pass membrane receptors contain extracellular domains that respond to external stimuli and transmit information to intracellular domains through a single transmembrane (TM) α-helix. Because membrane receptors have various roles in homeostasis, signaling malfunctions of these receptors can cause disease. Despite their importance, there is still much to be understood mechanistically about how single-pass receptors are activated. In general, single-pass receptors respond to extracellular stimuli via alterations in their oligomeric state. The details of this process are still the focus of intense study, and several lines of evidence indicate that the TM domain (TMD) of the receptor plays a central role. We discuss three major mechanistic hypotheses for receptor activation: ligand-induced dimerization, ligand-induced rotation, and receptor clustering. Recent observations suggest that receptors can use a combination of these activation mechanisms and that technical limitations can bias interpretation. Short peptides derived from receptor TMDs, which can be identified by screening or rationally developed on the basis of the structure or sequence of their targets, have provided critical insights into receptor function. Here, we explore recent evidence that, depending on the target receptor, TMD peptides cannot only inhibit but also activate target receptors and can accommodate novel, bifunctional designs. Furthermore, we call for more sharing of negative results to inform the TMD peptide field, which is rapidly transforming into a suite of unique tools with the potential for future therapeutics.

Radiosensitizers in the temozolomide era for newly diagnosed glioblastoma

Glioblastoma (GBM) is a challenging diagnosis with almost universally poor prognosis. Though the survival advantage of postoperative radiation (RT) is well established, around 90% of patients will fail in the RT field. The high likelihood of local failure suggests the efficacy of RT needs to be improved to improve clinical outcomes. Radiosensitizers are an established method of enhancing RT cell killing through the addition of a pharmaceutical agent. Though the majority of trials using radiosensitizers have historically been unsuccessful, there continues to be interest with a variety of approaches having been employed. Epidermal growth factor receptor inhibitors, histone deacetylase inhibitors, antiangiogenic agents, and a number of other molecularly targeted agents have all been investigated as potential methods of radiosensitization in the temozolomide era. Outcomes have varied both in terms of toxicity and survival, but some agents such as valproic acid and bortezomib have demonstrated promising results. However, reporting of results in phase 2 trials in newly diagnosed GBM have been inconsistent, with no standard in reporting progression-free survival and toxicity. There is a pressing need for investigation of new agents; however, nearly all phase 3 trials of GBM patients of the past 25 years have demonstrated no improvement in outcomes. One proposed explanation for this is the selection of agents lacking sufficient preclinical data and/or based on poorly designed phase 2 trials. Radiosensitization may represent a viable strategy for improving GBM outcomes in newly diagnosed patients, and further investigation using agents with promising phase 2 data is warranted.

The transition model of RTK activation: A quantitative framework for understanding RTK signaling and RTK modulator activity

Here, we discuss the transition model of receptor tyrosine kinase (RTK) activation, which is derived from biophysical investigations of RTK interactions and signaling. The model postulates that (1) RTKs can interact laterally to form dimers even in the absence of ligand, (2) different unliganded RTK dimers have different stabilities, (3) ligand binding stabilizes the RTK dimers, and (4) ligand binding causes structural changes in the RTK dimer. The model is grounded in the principles of physical chemistry and provides a framework to understand RTK activity and to make predictions in quantitative terms. It can guide basic research aimed at uncovering the mechanism of RTK activation and, in the long run, can empower the search for modulators of RTK function.

Recurrent Glioblastomas Exhibit Higher Expression of Biomarkers with Stem-like Properties

Background

Despite advances in the treatment of glioblastoma (GBM), the prognosis of patients continues to remain dismal. This unfavorable prognosis is mainly attributed to the tumor's propensity for progression and recurrence, which in turn is due to the highly aggressive nature of the persisting GBM cells that actively egress from the main tumor mass into the surrounding normal brain tissue. Such a recurrent tumor described to have a more malignant potential is highly invasive and resistant to current therapies, probably due to increased stemness and preferential selection of therapy-resistant clones of tumor cells. However, there is a paucity of literature on the expression of biomarkers in the recurrent GBM tumors that could have a role in conferring this aggressiveness.

Aim

To identify the differences in the expression pattern of selected biomarkers in paired tissue samples of GBM.

Material and Methods

A retrospective study on 30 paired samples of GBM (newly diagnosed/primary and recurrent) archived in the Department of Neuropathology, NIMHANS (2006-2009), was carried out. After obtaining clinical and demographic details, tumors were characterized histomorphologically and immunohistochemically on formalin-fixed paraffin-embedded tissues with reference to expression of biomarkers such as p53, epidermal growth factor receptor (EGFR), insulin-like growth factor binding protein 3 (IGFBP-3), sex determining region Y-box 2 (SOX2), and topoisomerase 2 A (Top2A). The results were statistically analyzed.

Results

It was observed that while p53 and IGFBP-3 expression remained unaltered in paired samples, a significant increase in the expression of EGFR (P < 0.01) was noted in the recurrent tumors. Among the other biomarkers, SOX2 expression was higher in the recurrent tumors when compared to the primary tumors (P < 0.01). Conversely, the expression of Top2A was reduced in recurrent tumors (P = 0.05). Mild elevation in the expression of IGFBP-3 was observed in recurrent tumors but was not statistically significant.

Conclusion

A significant increase in the expression of SOX2 in recurrent tumors probably indicates the presence of undifferentiated cells with stem-like properties in these tumors. EGFR is known to mediate SOX2 expression thereby resulting in stemness of the glioma cancer cells, which could further explain its overexpression in recurrent GBMs. Furthermore, a decreased expression of TOP2A observed in the recurrent tumors could probably be due to reduction in chemosensitivity to temozolomide, which has been shown in earlier studies. We also noted that p53 expression remained unaltered in the recurrent tumors when compared to the primary, suggesting the absence of preferential clonal expansion of p53 mutant cells following exposure to radiochemotherapy. Our study reiterates the fact that GBM recurrences are associated with molecular alterations that probably contribute to radiochemoresistance, increased invasiveness, therapeutic efficacy, and stemness.

Age differences in photodynamic therapy-mediated opening of the blood-brain barrier through the optical clearing skull window in mice

BACKGROUND

Photodynamic therapy (PDT), a minimally invasive therapeutic tool, has been an important option for post-surgical treatment of malignant gliomas (MGs) in both adult and young patients. Recent studies have shown that PDT can also open the blood-brain barrier (BBB). However, there are no optimized parameters of PDT for patients at different ages. To determine whether there are age differences in PDT effects on the BBB, we studied PDT-related BBB opening through the optical clearing skull window in healthy 4- and 8-week-old mice.

METHODS

In this work, we realized BBB opening by combining PDT with the optical clearing skull window by using different radiant exposures (635 nm, 10-20-30-40 J/cm² ) and 5-aminole-vulinic acid (5-ALA, 20 mg/kg). Then, we evaluated BBB permeability by: (i) spectrofluorimetric measuring of Evans Blue dye (EBd) leakage; (ii) confocal imaging of 70 kDa FITC-dextran extravasation and the BBB integrity; and (iii) histological analysis of brain tissues.

RESULTS

Using the skull optical clearing method, we demonstrated PDT-induced BBB opening to EBd and FITC-dextran in a radiant exposure manner. The histological analysis revealed the different severities of vasogenic edema corresponding to radiant exposures. Besides, the PDT-related increase in the BBB permeability to high weight molecules (EBd and FITC-dextran) and solutes (vasogenic edema) was more pronounced in 4-week-old mice than in 8-week-old mice.

CONCLUSIONS

The more pronounced PDT-induced BBB disruption in juvenile mice compared with adult mice suggests age differences in PDT-related BBB opening. This might be an important informative platform for a new application of PDT as a method for brain drug delivery, especially for post-surgical treatment of MGs. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Expression Density of Receptors as a Potent Regulator of Cell Function and Property in Health and Pathology

The expression of cytokine receptors has a crucial role in many cellular processes. Recent studies reported that changes of receptor expression could control the action of mediators on target cells. The initiation of different signaling pathways and, therefore, specific effects on cells, depends on certain components forming the cytokine-receptor complex. These mechanisms control the immune response and affect both the course of diseases (oncological, autoimmune, inflammatory) and the effectiveness of therapy. This review describes the potential of immune mediator receptors to regulate the efficiency of cytokine activity during pathologic processes and ensure the variability of their biological effects. Our aim was to investigate the spectrum of potential roles of changes in mediator receptor expression for main classes of pathologies. For all major types of immune mediators (cytokines, interleukins, chemokines, growth factors, and tumor necrosis factors), it has been shown that changes in their receptor expression are associated with impaired functioning of the organism in chronic diseases.

The Effect of Canertinib on Sensitivity of Cytotoxic Drugs in Tamoxifen-Resistant Breast Cancer Cells In Vitro

Aims and Objectives

To investigate and examine the reversal effects of canertinib on the activity of EGFR and tamoxifen resistance in drug-resistant human breast carcinoma cells (MCF-7/TamR).

Materials and Methods

The antiproliferative activity of canertinib alone or in combination with a conventional EGFR-targeting chemotherapies cytotoxic drugs differing in the mechanism(s) of action, such as paclitaxel, carboplatin, etoposide, vinorelbine, and daunorubicin as well as resistance mechanisms of EGFR targeting, have been investigated.

Results

With an elevated dosage of canertinib, a significant decrease in proliferation and increase in apoptosis was observed. The treatment with higher doses of canertinib resulted in a 2-3-fold increase in apoptosis. In the combined treatment, it had been noticed a significant developed apoptotic cell death rather induced by single agent treatment. A significant downregulation of the antiapoptotic protein bcl-2 was exposed by immunocytochemistry investigation. Sensitivity to paclitaxel was also measured and was found to inversely correlate to bcl-2 status.

Conclusion

Proliferation inhibition and apoptosis in MCF-7/TAM-R cells increase with increasing dosage of canertinib. This suggests that canertinib can reverse tamoxifen resistance in breast cancer cells. The antitumor effect of this EGFR-irreversible tyrosine kinase inhibitor provides a rationale for its clinical evaluation in combination with other cytotoxic drugs.

Interactions between NRP1 and VEGFR2 molecules in the plasma membrane

Here we use a quantitative FRET approach, specifically developed to probe membrane protein interactions, to study the homo-association of neuropilin 1 (NRP1) in the plasma membrane, as well as its hetero-interactions with vascular endothelial growth factor receptor 2 (VEGFR2). Experiments are performed both in the absence and presence of the soluble ligand vascular endothelial growth factor A (VEGFA), which binds to both VEGFR2 and NRP1. We demonstrate the presence of homo-interactions between NRP1 molecules, as well as hetero-interactions between NRP1 and VEGFR2 molecules, in the plasma membrane. Our results underscore the complex nature of the interactions between self-associating receptors, co-receptors, and their ligands in the plasma membrane. They also highlight the need for new methodologies that capture this complexity, and the need for precise physiological measurements of local receptor surface densities in the membrane of cells. This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo.

Classification of cancer cells using computational analysis of dynamic morphology

BACKGROUND AND OBJECTIVE

Detection of metastatic tumor cells is important for early diagnosis and staging of cancer. However, such cells are exceedingly difficult to detect from blood or biopsy samples at the disease onset. It is reported that cancer cells, and especially metastatic tumor cells, show very distinctive morphological behavior compared to their healthy counterparts on aptamer functionalized substrates. The ability to quickly analyze the data and quantify the cell morphology for an instant real-time feedback can certainly contribute to early cancer diagnosis. A supervised machine learning approach is presented for identification and classification of cancer cell gestures for early diagnosis.

METHODS

We quantified the morphologically distinct behavior of metastatic cells and their healthy counterparts captured on aptamer-functionalized glass substrates from time-lapse optical micrographs. As a proof of concept, the morphologies of human glioblastoma (hGBM) and astrocyte cells were used. The cells were captured and imaged with an optical microscope. Multiple feature vectors were extracted to quantify and differentiate the complex physical gestures of cancerous and non-cancerous cells. Three different classifier models, Support Vector Machine (SVM), Random Forest Tree (RFT), and Naïve Bayes Classifier (NBC) were trained with the known dataset using machine learning algorithms. The performances of the classifiers were compared for accuracy, precision, and recall measurements using five-fold cross-validation technique.

RESULTS

All the classifier models detected the cancer cells with an average accuracy of at least 82%. The NBC performed the best among the three classifiers in terms of Precision (0.91), Recall (0.9), and F₁-score (0.89) for the existing dataset.

CONCLUSIONS

This paper presents a standalone system built on machine learning techniques for cancer screening based on cell gestures. The system offers rapid, efficient, and novel identification of hGBM brain tumor cells and can be extended to define single cell analysis metrics for many other types of tumor cells.

Prognostic Implication of Clinical and Pathologic Features in Patients with Glioblastoma Multiforme Treated with Concomitant Radiation plus Temozolomide

Aims and background

Glioblastoma multiforme is the most common and most malignant primary brain tumor in adults. The current standard of care for glioblastoma is surgical resection to the extent feasible, followed by adjuvant radiotherapy plus temozolomide, given concomitantly with and after radiotherapy. This report is a prospective observational study of 43 cases treated in the Department of Radiotherapy, University of Rome La Sapienza, Italy. We examine the relationship between pathologic features and objective response rate in adult patients treated with concomitant radiation plus temozolomide to identify clinical, neuroradiologic, pathologic, and molecular factors with prognostic significance.

Methods

Forty-three consecutive patients (24 males and 19 females), ages 15-77 years (median, 57) with newly diagnosed glioblastoma multiforme, were included in this trial between 2002 and 2004 at our department. All patients were treated with surgery (complete resection in 81%, incomplete in 19%) followed by concurrent temozolomide (75 mg/m2/day) and radiotherapy (median tumor dose, 60 Gy), followed by temozolomide, 200 mg/m2/day for 5 consecutive days every 28 days. Neurologic evaluations were performed monthly and cranial magnetic resonance bimonthly. We analyzed age, clinical manifestations at diagnosis, seizures, Karnofsky performance score, tumor location, extent of resection, proliferation index (Ki-67 expression), p53, platelet-derived growth factor and epidermal growth factor receptor immunohistochemical expression as prognostic factors in the patients. The Kaplan-Meier statistical method and logrank test were used to assess correlation with survival.

Results

Fourteen patients (32%) manifested clinical and neuroradiographic evidence of tumor progression within 6 months of surgery. In contrast, 5 patients (12%) showed no disease progression for 18 months from the beginning of treatment. Median overall survival was 19 months. Multivariate analysis revealed that an age of 60 years or older (P <0.03), a postoperative performance score ≤70 (P = 0.04), the nontotal tumor resection (P = 0.03), tumor size >4 cm (P = 0.01) and proliferation index overexpression (P = 0.001) were associated with the worst prognosis. p53, PDGF and EGFR overexpression were not significant prognostic factors associated with survival.

Conclusions

The results suggest that analysis of prognostic markers in glioblastoma multiforme is complex. In addition to previously recognized prognostic variables such as age and Karnofsky performance score, tumor size, total resection and proliferation index overexpression were identified as predictors of survival in a series of patients with glioblastoma multiforme.

Epidermal Growth Factor Receptor Serum Levels and Prognostic Value in Malignant Gliomas

Aims and background

The epidermal growth factor receptor (EGFR) is a member of a family of cell membrane receptors that use tyrosine kinase activity as the signal transduction mechanism. It is commonly expressed or overexpressed by many solid tumors and correlates with disease progression and a poor clinical prognosis. Increased EGFR expression might therefore be a strong prognostic feature in multiple tumor types, and inhibition of its cellular actions may have substantial therapeutic benefit. The aim of this study was to estimate the EGFR serum concentration for potential use as a biological marker of brain cancer to predict prognosis and follow-up after treatment.

Methods and study design

Serum samples obtained from 50 healthy individuals and 65 brain cancer patients (35 glioblastoma multiforme and 30 anaplastic astrocytomas) were collected before and after treatment and assayed for EGFR extracellular domain serum concentrations by a sandwich ELISA.

Results

EGFR was elevated in 47 of 65 brain cancer patients, with mean serum values of 84 ± 18 ng/ml, compared with that of healthy controls (43.6 ± 11 ng/ml, P = 0.001). There was a significant difference in the mean serum levels of EGFR between glioblastoma multiforme patients (96.2 ± 12 ng/ml) and anaplastic astrocytoma patients (71.6 ± 18 ng/ml, P = 0.04). Sixty brain cancer patients underwent surgery; EGFR serum levels did not show significant differences from those observed before surgery. For all patients, median overall survival was 13 months (anaplastic astrocytoma, 18 months; glioblastoma multiforme, 12.5 months). In 47 patients with high EGFR serum levels, overall survival was reduced (P = 0. 01), with a median survival time corresponding to 11.5 months (anaplastic astrocytoma, 14.5 months; glioblastoma multiforme, 10.5 months).

Conclusions

Although a prospective study with large sample size is warranted, serum EGFR extracellular domain may be potentially useful as a biological marker of gliomas for prediction of prognosis and follow-up after treatment.

The Influence of EGFR Inactivation on the Radiation Response in High Grade Glioma

Lack of effectiveness of radiation therapy may arise from different factors such as radiation induced receptor tyrosine kinase activation and cell repopulation; cell capability to repair radiation induced DNA damage; high grade glioma (HGG) tumous heterogeneity, etc. In this study, we analyzed the potential of targeting epidermal growth factor receptor (EGFR) in inducing radiosensitivity in two human HGG cell lines (11 and 15) that displayed similar growth patterns and expressed the receptor protein at the cell surface. We found that 15 HGG cells that express more EGFR at the cell surface were more sensitive to AG556 (an EGFR inhibitor), compared to 11 HGG cells. Although in line 15 the effect of the inhibitor was greater than in line 11, it should be noted that the efficacy of this small-molecule EGFR inhibitor as monotherapy in both cell lines has been modest, at best. Our data showed a slight difference in the response to radiation of the HGG cell lines, three days after the treatment, with line 15 responding better than line 11. However, both cell lines responded to ionizing radiation in the same way, seven days after irradiation. EGFR inhibition induced radiosensitivity in 11 HGG cells, while, in 15 HGG cells, the effect of AG556 treatment on radiation response was almost nonexistent.

Report of safety of pulse dosing of lapatinib with temozolomide and radiation therapy for newly-diagnosed glioblastoma in a pilot phase II study

Epidermal growth factor receptor (EGFR) mutations are commonly observed in Glioblastoma (GBM) and have long posed as a target for new therapies. Trials involving erlotinib have shown mixed results, likely owing to a mechanism of the mutation that may instead favor other EGFR inhibitors, such as lapatinib. We aimed to determine whether or not pulse high-dose lapatinib was a safe and tolerable regimen in addition to standard therapy. We recruited adult patients with newly-diagnosed GBM who had Karnofsky Performance Status ≥60, normal baseline hematological, hepatic, and renal function tests, and no prior history of radiation or treatment with EGFR inhibitor. Lapatinib was administered at 2500 mg twice daily for two consecutive days per week on a weekly basis throughout concomitant and adjuvant standard therapy. The primary endpoints were tolerability and safety. 12 patients were enrolled in this study over 2 years. Of the non-hematological adverse events, there were 2 grade 3 events, fatigue and post-radiation cystic brain necrosis. The most common adverse events in general were fatigue, rashes, and diarrhea. Of the hematological adverse events, there were 13 grade 3 events, all of which were due to lymphopenia and affected 6 of 12 patients. Pulse high-dose lapatinib in addition to standard therapy for newly-diagnosed GBM is a tolerable and safe regimen, but higher rates of lymphopenia should be noted. However, further investigations will be required to evaluate the efficacy of this combination for the treatments of GBM. Trial registration ClinicalTrials.gov Identifier: NCT01591577.

Relationship Between Cytogenetic Complexity and Peritumoral Edema in High-Grade Astrocytoma

BACKGROUND

The purpose of the study is to reveal the association of cytogenetic compltyexi and peritumoral edema volume (PTEV) and its prognostic significance in high-grade astrocytoma patients by culturing patient tumor cells.

METHODS

Twenty-seven high-grade astrocytoma patients were divided into three groups according to karyotype complexity: normal, non-complex karyotype (NCK), and complex karyotype (CK). Endothelial growth factor receptor (EGFR) amplification was detected by FISH, and its association with chromosome 7 abnormalities was analyzed. Mean PTEV of each group was compared by ANOVA to evaluate the relationship between PTEV and cytogenetic complexity.

RESULTS

The PTEV of patients in normal (n=6), NCK (n=8), and CK (n=13) groups were 24.52±17.73, 34.26±35.04, and 86.31±48.7 cm³, respectively (P=0.005). Ten out of 11 patients with EGFR amplification showed abnormalities in chromosome 7. The mean PTEV of EGFR-amplified and non-amplified groups were 80.4±53.7 and 41.3±37.9 cm³, respectively (P=0.035). The average survival of patients with PTEV less than 90 cm³ was 30.52±26.11 months, while in patients with PTEVs over or equal to 90 cm³, it was 10.83±5.53 months (P=0.007).

CONCLUSIONS

The results show an association of complex karyotype with the PTEV of high-grade astrocytoma. EGFR amplification plays a significant role in the formation of peritumoral edema, causing PTEV to increase, which is related with survival. This implies that cytogenetic karyotype can be applied as a prognostic factor.

Resistance of Nonmelanoma Skin Cancer to Nonsurgical Treatments. Part II: Photodynamic Therapy, Vismodegib, Cetuximab, Intralesional Methotrexate, and Radiotherapy

A wide range of treatments is now available for nonmelanoma skin cancer, including 5-fluorouracil, ingenol mebutate, imiquimod, diclofenac, photodynamic therapy, methotrexate, cetuximab, vismodegib, and radiotherapy. All are associated with high clinical and histologic response rates. However, some tumors do not respond due to resistance, which may be primary or acquired. Study of the resistance processes is a broad area of research that aims to increase our understanding of the nature of each tumor and the biologic features that make it resistant, as well as to facilitate the design of new therapies directed against these tumors. In this second article, having covered the topical treatments of nonmelanoma skin cancer, we review resistance to other nonsurgical treatments, such as monoclonal antibodies against basal and squamous cell carcinomas, intralesional chemotherapy, photodynamic therapy, and radiotherapy.

A small peptide promotes EphA2 kinase-dependent signaling by stabilizing EphA2 dimers

BACKGROUND

The EphA2 receptor tyrosine kinase is known to promote cancer cell malignancy in the absence of activation by ephrin ligands. This behavior depends on high EphA2 phosphorylation on Ser897 and low tyrosine phosphorylation, resulting in increased cell migration and invasiveness. We have previously shown that EphA2 forms dimers in the absence of ephrin ligand binding, and that dimerization of unliganded EphA2 can decrease EphA2 Ser897 phosphorylation. We have also identified a small peptide called YSA, which binds EphA2 and competes with the naturally occurring ephrin ligands.

METHODS

Here, we investigate the effect of YSA on EphA2 dimer stability and EphA2 function using quantitative FRET techniques, Western blotting, and cell motility assays.

RESULTS

We find that the YSA peptide stabilizes the EphA2 dimer, increases EphA2 Tyr phosphorylation, and decreases both Ser897 phosphorylation and cell migration.

CONCLUSIONS

The experiments demonstrate that the small peptide ligand YSA reduces EphA2 Ser897 pro-tumorigenic signaling by stabilizing the EphA2 dimer.

GENERAL SIGNIFICANCE

This work is a proof-of-principle demonstration that EphA2 homointeractions in the plasma membrane can be pharmacologically modulated to decrease the pro-tumorigenic signaling of the receptor.

Molecularly targeted therapy for the treatment of head and neck cancer: a review of the ErbB family inhibitors

The majority of patients with head and neck squamous cell carcinoma (HNSCC) present with locally advanced disease, which requires site-specific combinations of surgery, radiation, and chemotherapy. Despite aggressive therapy, survival outcomes remain poor, and treatment-related morbidity is not negligible. For patients with recurrent or metastatic disease, therapeutic options are further limited and prognosis is dismal. With this in mind, molecularly targeted therapy provides a promising approach to optimizing treatment efficacy while minimizing associated toxicity. The ErbB family of receptors (ie, epidermal growth factor receptor [EGFR], ErbB2/human epidermal growth factor receptor [HER]-2, ErbB3/HER3, and ErbB4/HER4) is known to contribute to oncogenic processes, such as cellular proliferation and survival. EGFR, specifically, is upregulated in more than 90% of HNSCC, has been implicated in radiation resistance, and correlates with poorer clinical outcomes. The central role of EGFR in the pathogenesis of HNSCC suggests that inhibition of this pathway represents an attractive treatment strategy. As a result, EGFR inhibition has been extensively studied, with the emergence of two classes of drug therapy: monoclonal antibodies and tyrosine kinase inhibitors. While the monoclonal antibody cetuximab is currently the only US Food and Drug Administration-approved EGFR inhibitor for the treatment of HNSCC, numerous investigational drugs are being evaluated in clinical trials. This paper will review the role of the ErbB family in the pathogenesis of HNSCC, as well as the evidence-based data for the use of ErbB family inhibition in clinical practice.

Imaging Genomics of Glioblastoma: Biology, Biomarkers, and Breakthroughs

Glioblastoma is regarded as the most aggressive and most common primary malignant brain tumor in adults. Despite advancements in chemotherapy and radiotherapy, prognosis and overall survival of glioblastoma patients remain dismal. Recently, progresses in genetic profiling have increased our understanding of the underlying heterogenous molecular nature of this aggressive tumor. Several prognostic and predictive molecular biomarkers have been identified that have been linked to patient's survival and response to treatment, respectively. Imaging genomics represents a novel entity in clinical sciences that bidirectionally links imaging features with underlying molecular profile and thus can serve as a surrogate for noninvasive genomic correlation, prediction, and identification.

One-step tumor detection from dynamic morphology tracking on aptamer-grafted surfaces

In this paper, we report a one-step tumor cell detection approach based on the dynamic morphological behavior tracking of cancer cells on a ligand modified surface. Every cell on the surface was tracked in real time for several minutes immediately after seeding until these were finally attached. Cancer cells were found to be very active in the aptamer microenvironment, changing their shapes rapidly from spherical to semi-elliptical, with much flatter spread and extending pseudopods at regular intervals. When incubated on a functionalized surface, the balancing forces between cell surface molecules and the surface-bound aptamers, together with the flexibility of the membranes, caused cells to show these distinct dynamic activities and variations in their morphologies. On the other hand, healthy cells remained distinguishingly inactive on the surface over the same period. The quantitative image analysis of cell morphologies provided feature vectors that were statistically distinct between normal and cancer cells.

Bcl-2 family member Mcl-1 expression is reduced under hypoxia by the E3 ligase FBW7 contributing to BNIP3 induced cell death in glioma cells

Mcl-1 is an anti-apoptotic Bcl-2 family member that is often over-expressed in the malignant brain tumor glioblastoma (GBM). It has been previously shown that epidermal growth factor receptors up-regulate Mcl-1 contributing to a cell survival response. Hypoxia is a poor prognostic marker in glioblastoma despite the fact that hypoxic regions have areas of necrosis. Hypoxic regions of GBM also highly express the pro-cell death Bcl-2 family member BNIP3, yet when BNIP3 is overexpressed in glioma cells, it induces cell death. The reasons for this discrepancy are unclear. Herein we have found that Mcl-1 expression is reduced under hypoxia due to degradation by the E3 ligase FBW7 leading to increased hypoxia induced cell death. This cell death is reduced by EGFR activation leading to increased Mcl-1 expression under hypoxia. Conversely, BNIP3 is over-expressed in hypoxia at times when Mcl-1 expression is decreased. Knocking down BNIP3 expression reduces hypoxia cell death and Mcl-1 expression effectively blocks BNIP3 induced cell death. Of significance, BNIP3 and Mcl-1 are co-localized under hypoxia in glioma cells. These results suggest that Mcl-1 can block the ability of BNIP3 to induce cell death under hypoxia in GBM tumors.

Phosphorylation of Glutathione S-Transferase P1 (GSTP1) by Epidermal Growth Factor Receptor (EGFR) Promotes Formation of the GSTP1-c-Jun N-terminal kinase (JNK) Complex and Suppresses JNK Downstream Signaling and Apoptosis in Brain Tumor Cells

Under normal physiologic conditions, the glutathione S-transferase P1 (GSTP1) protein exists intracellularly as a dimer in reversible equilibrium with its monomeric subunits. In the latter form, GSTP1 binds to the mitogen-activated protein kinase, JNK, and inhibits JNK downstream signaling. In tumor cells, which frequently are characterized by constitutively high GSTP1 expression, GSTP1 undergoes phosphorylation by epidermal growth factor receptor (EGFR) at tyrosine residues 3, 7, and 198. Here we report on the effect of this EGFR-dependent GSTP1 tyrosine phosphorylation on the interaction of GSTP1 with JNK, on the regulation of JNK downstream signaling by GSTP1, and on tumor cell survival. Using in vitro and in vivo growing human brain tumors, we show that tyrosine phosphorylation shifts the GSTP1 dimer-monomer equilibrium to the monomeric state and facilitates the formation of the GSTP1-JNK complex, in which JNK is functionally inhibited. Targeted mutagenesis and functional analysis demonstrated that the increased GSTP1 binding to JNK results from phosphorylation of the GSTP1 C-terminal Tyr-198 by EGFR and is associated with a >2.5-fold decrease in JNK downstream signaling and a significant suppression of both spontaneous and drug-induced apoptosis in the tumor cells. The findings define a novel mechanism of regulatory control of JNK signaling that is mediated by the EGFR/GSTP1 cross-talk and provides a survival advantage for tumors with activated EGFR and high GSTP1 expression. The results lay the foundation for a novel strategy of dual EGFR/GSTP1 for treating EGFR+ve, GSTP1 expressing GBMs.

Glioblastoma multiforme: emerging treatments and stratification markers beyond new drugs

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults. The standard therapy for GBM is maximal surgical resection followed by radiotherapy with concurrent and adjuvant temozolomide (TMZ). In spite of the extensive treatment, the disease is associated with poor clinical outcome. Further intensification of the standard treatment is limited by the infiltrating growth of the GBM in normal brain areas, the expected neurological toxicities with radiation doses >60 Gy and the dose-limiting toxicities induced by systemic therapy. To improve the outcome of patients with GBM, alternative treatment modalities which add low or no additional toxicities to the standard treatment are needed. Many Phase II trials on new chemotherapeutics or targeted drugs have indicated potential efficacy but failed to improve the overall or progression-free survival in Phase III clinical trials. In this review, we will discuss contemporary issues related to recent technical developments and new metabolic strategies for patients with GBM including MR (spectroscopy) imaging, (amino acid) positron emission tomography (PET), amino acid PET, surgery, radiogenomics, particle therapy, radioimmunotherapy and diets.

Combined epidermal growth factor receptor and Beclin1 autophagic protein expression analysis identifies different clinical presentations, responses to chemo- and radiotherapy, and prognosis in glioblastoma

Dysregulated EGFR in glioblastoma may inactivate the key autophagy protein Beclin1. Each of high EGFR and low Beclin1 protein expression, independently, has been associated with tumor progression and poor prognosis. High (H) compared to low (L) expression of EGFR and Beclin1 is here correlated with main clinical data in 117 patients after chemo- and radiotherapy. H-EGFR correlated with low Karnofsky performance and worse neurological performance status, higher incidence of synchronous multifocality, poor radiological evidence of response, shorter progression disease-free (PDFS), and overall survival (OS). H-Beclin1 cases showed better Karnofsky performance status, higher incidence of objective response, longer PDFS, and OS. A mutual strengthening effect emerges in correlative power of stratified L-EGFR and H-Beclin1 expression with incidence of radiological response after treatment, unifocal disease, and better prognosis, thus identifying an even longer OS group (30 months median OS compared to 18 months in L-EGFR, 15 months in H-Beclin1, and 11 months in all GBs) (P = 0.0001). Combined L-EGFR + H-Beclin1 expression may represent a biomarker in identifying relatively favorable clinical presentations and prognosis, thus envisaging possible EGFR/Beclin1-targeted therapies.

Targeted therapy in gliomas

The survival outcome of patients with malignant gliomas is still poor, despite advances in surgical techniques, radiation therapy and the development of novel chemotherapeutic agents. The heterogeneity of molecular alterations in signaling pathways involved in the pathogenesis of these tumors contributes significantly to their resistance to treatment. Several molecular targets for therapy have been discovered over the last several years. Therapeutic agents targeting these signaling pathways may provide more effective treatments and may improve survival. This review summarizes the important molecular therapeutic targets and the outcome of published clinical trials involving targeted therapeutic agents in glioma patients.

Selection of DNA aptamers against epidermal growth factor receptor with high affinity and specificity

Epidermal growth factor receptor (EGFR/HER1/c-ErbB1), is overexpressed in many solid cancers, such as epidermoid carcinomas, malignant gliomas, etc. EGFR plays roles in proliferation, invasion, angiogenesis and metastasis of malignant cancer cells and is the ideal antigen for clinical applications in cancer detection, imaging and therapy. Aptamers, the output of the systematic evolution of ligands by exponential enrichment (SELEX), are DNA/RNA oligonucleotides which can bind protein and other substances with specificity. RNA aptamers are undesirable due to their instability and high cost of production. Conversely, DNA aptamers have aroused researcher's attention because they are easily synthesized, stable, selective, have high binding affinity and are cost-effective to produce. In this study, we have successfully identified DNA aptamers with high binding affinity and selectivity to EGFR. The aptamer named TuTu22 with Kd 56±7.3nM was chosen from the identified DNA aptamers for further study. Flow cytometry analysis results indicated that the TuTu22 aptamer was able to specifically recognize a variety of cancer cells expressing EGFR but did not bind to the EGFR-negative cells. With all of the aforementioned advantages, the DNA aptamers reported here against cancer biomarker EGFR will facilitate the development of novel targeted cancer detection, imaging and therapy.

Nimotuzumab combined with radiotherapy for esophageal cancer: preliminary study of a Phase II clinical trial

OBJECTIVE

To determine the safety and therapeutic effects of nimotuzumab (h-R3) combined with radiotherapy in esophageal cancer.

METHODS

This Phase II clinical trial involved 42 patients with stage II (inoperable or refused surgery) to stage IV (supraclavicular lymph node metastasis only) esophageal cancers treated between November 2008 and July 2010. All patients had squamous cell carcinomas, and all received three-dimensional conformal radiotherapy and 200 mg nimotuzumab per week during radiotherapy.

RESULTS

There were 9, 25, and 8 patients with stage II, III and IV disease, respectively. All except two patients received 50-70 Gy radiation; 37 patients (88.1%) received more than five nimotuzumab doses. Grade III toxicities (21.4% of all adverse events) included esophagitis and gastrointestinal, dermatological and hematological toxicities. Complete response, partial response, stable disease, and progressive disease were observed in 0, 22 (52.4%), 17 (40.5%) and 3 (7.1%) patients at 1 month after the treatment. The epidermal growth factor receptor (EGFR) overexpression rate was 95.2%. After a median follow-up of 37 months, the median survival time (MST) was 14 months. The 2 year and 3 year overall survival (OS) rates were 33.3% and 26.2%, respectively. The median progression-free survival (PFS) time was 10 months. The 2 year and 3 year PFS rates were 24.5% and 22.1%, respectively. The MST in the 13 patients with (+++) EGFR expression (group A) and 7 patients with (++) EGFR expression (group B) was 15 and 11 months, respectively. The 2 year and 3 year OS rates were 46.2% and 38.5% in group A and 28.6% and 28.6% in group B, respectively (P = 0.405).

CONCLUSION

Although concurrent chemoradiotherapy was the standard care for locally advanced esophageal cancer, radiotherapy was the choice for those who were refused or could not tolerate chemoradiotherapy. Our study shows that nimotuzumab combined with radiotherapy was well tolerated in patients with esophageal cancer. EGFR overexpression was more common than previously reported. OS was higher after combined therapy than after historical control radiotherapy alone. Further studies are required to confirm the therapeutic efficacy of nimotuzumab in esophageal cancer.

Combining molecular targeted agents with radiation therapy for malignant gliomas

The expansion in understanding the molecular biology that characterizes cancer cells has led to the rapid development of new agents to target important molecular pathways associated with aberrant activation or suppression of cellular signal transduction pathways involved in gliomagenesis, including epidermal growth factor receptor, vascular endothelial growth factor receptor, mammalian target of rapamycin, and integrins signaling pathways. The use of antiangiogenic agent bevacizumab, epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib, mammalian target of rapamycin inhibitors temsirolimus and everolimus, and integrin inhibitor cilengitide, in combination with radiation therapy, has been supported by encouraging preclinical data, resulting in a rapid translation into clinical trials. Currently, the majority of published clinical studies on the use of these agents in combination with radiation and cytotoxic therapies have shown only modest survival benefits at best. Tumor heterogeneity and genetic instability may, at least in part, explain the poor results observed with a single-target approach. Much remains to be learned regarding the optimal combination of targeted agents with conventional chemoradiation, including the use of multipathways-targeted therapies, the selection of patients who may benefit from combined treatments based on molecular biomarkers, and the verification of effective blockade of signaling pathways.