The mechanism of chemoresistance against tyrosine kinase inhibitors in malignant glioma

Targeting glycolysis: exploring a new frontier in glioblastoma therapy

Glioblastoma(GBM) is a highly malignant primary central nervous system tumor that poses a significant threat to patient survival due to its treatment resistance and rapid recurrence.Current treatment options, including maximal safe surgical resection, radiotherapy, and temozolomide (TMZ) chemotherapy, have limited efficacy.In recent years, the role of glycolytic metabolic reprogramming in GBM has garnered increasing attention. This review delves into the pivotal role of glycolytic metabolic reprogramming in GBM, with a particular focus on the multifaceted roles of lactate, a key metabolic product, within the tumor microenvironment (TME). Lactate has been implicated in promoting tumor cell proliferation, invasion, and immune evasion. Additionally, this review systematically analyzes potential therapeutic strategies targeting key molecules within the glycolytic pathway, such as Glucose Transporters (GLUTs), Monocarboxylate Transporters(MCTs), Hexokinase 2 (HK2), 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 3 (PFKFB3), Pyruvate Kinase Isozyme Type M2 (PKM2), and the Lactate Dehydrogenase A (LDHA). These studies provide a novel perspective for GBM treatment. Despite progress made in existing research, challenges remain, including drug penetration across the blood-brain barrier, side effects, and resistance. Future research will aim to address these challenges by improving drug delivery, minimizing side effects, and exploring combination therapies with radiotherapy, chemotherapy, and immunotherapy to develop more precise and effective personalized treatment strategies for GBM.

Resistance to hormone therapy in breast cancer cells promotes autophagy and EGFR signaling pathway

Breast cancer is the leading cause of cancer deaths for women worldwide. Endocrine therapies represent the cornerstone for hormone-dependent breast cancer treatment. However, in many cases, endocrine resistance is induced with poor prognosis for patients. In the current study, we have developed MCF-7 cell lines resistant to fulvestrant (MCF-7Fulv) and tamoxifen (MCF-7Tam) aiming at investigating mechanisms underlying resistance. Both resistant cell lines exerted lower proliferation capacity in two-dimensional (2-D) cultures but retain estrogen receptor α (ERα) expression and proliferate independent of the presence of estrogens. The established cell lines tend to be more aggressive exhibiting advanced capacity to form colonies, increased expression of epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), and heterodimerization of ERBB family receptors and activation of EGFR downstream pathways like MEK/ERK1/2 and PI3K/AKT. Tyrosine kinase inhibitors tested against resistant MCF-7Fulv and MCF-7Tam cells showed moderate efficacy to inhibit cell proliferation, except for lapatinib, which concomitantly inhibits both EGFR and HER2 receptors and strongly reduced cell proliferation. Furthermore, increased autophagy was observed in resistant MCF-7Fulv and MCF-7Tam cells as shown by the presence of autophagosomes and increased Beclin-1 levels. The increased autophagy in resistant cells is not associated with increased apoptosis, suggesting a cytoprotective role for autophagy that may favor cells' survival and aggressiveness. Thus, by exploiting those underlying mechanisms, new targets could be established to overcome endocrine resistance.NEW & NOTEWORTHY The development of resistance to hormone therapy caused by both fulvestrant and tamoxifen promotes autophagy with concomitant apoptosis evasion, rendering cells capable of surviving and growing. The fact that resistance also triggers ERBB family signaling pathways, which are poorly inhibited by tyrosine kinase inhibitors might attribute to cells' aggressiveness. It is obvious that the development of endocrine therapy resistance involves a complex interplay between deregulated ERBB signaling and autophagy that may be considered in clinical practice.

Gastrointestinally absorbable lactoferrin-heparin conjugate with anti-angiogenic activity for treatment of brain tumor

Glioblastoma multiforme (GBM) is a central nervous system disease with poor prognosis. Curative treatments for GBM involve chemotherapy, radiotherapy, and surgical pathways. Recently, antiangiogenic therapy through medications has been tried to slow tumor growth, but the drugs can induce side effects. To overcome these limitations, we developed a new orally absorbable form of heparin that can attenuate angiogenic activity by binding to growth factors around the tumor tissue. We conjugated lactoferrin (Lf) to heparin because Lf can be orally absorbed, and it interacts with the lactoferrin receptor (Lf-R) expressed on the intestine, blood-brain barrier (BBB), and glioma tumor masses. We successfully conjugated Lf and heparin by amide bond formation, as evidenced by advanced physicochemical properties such as pharmacokinetics and stability in acidic condition. This new material inhibited angiogenesis in vitro without toxicity. In addition, Lf-heparin administered orally to GBM orthotopic mice was absorbed in the small intestine and delivered specifically to the brain tumor by receptor transcytosis (Lf-R). Lf-heparin further attenuated angiogenesis progression in GBM orthotopic mice. Based on these results, Lf-heparin shows potential as a new oral medication for treatment of glioblastoma.

Tyrosine Kinase Inhibitors for Glioblastoma Multiforme: Challenges and Opportunities for Drug Delivery

Glioblastoma multiforme (GBM) is an aggressive brain tumor with high mortality rates. Due to its invasiveness, heterogeneity, and incomplete resection, the treatment is very challenging. Targeted therapies such as tyrosine kinase inhibitors (TKIs) have great potential for GBM treatment, however, their efficacy is primarily limited by poor brain distribution due to the presence of the blood-brain barrier (BBB). This review focuses on the potential of TKIs in GBM therapy and provides an insight into the reasons behind unsuccessful clinical trials of TKIs in GBM despite the success in treating other cancer types. The main section is dedicated to the use of promising drug delivery strategies for targeted delivery to brain tumors. Use of brain targeted delivery strategies can help enhance the efficacy of TKIs in GBM. Among various drug delivery approaches used to bypass or cross BBB, utilizing nanocarriers is a promising strategy to augment the pharmacokinetic properties of TKIs and overcome their limitations. This is because of their advantages such as the ability to cross BBB, chemical stabilization of drug in circulation, passive or active targeting of tumor, modulation of drug release from the carrier, and the possibility to be delivered via non-invasive intranasal route.

Next-Generation Anti-Angiogenic Therapies as a Future Prospect for Glioma Immunotherapy; From Bench to Bedside

Glioblastoma (grade IV glioma) is the most aggressive histopathological subtype of glial tumors with inordinate microvascular proliferation as one of its key pathological features. Extensive angiogenesis in the tumor microenvironment supplies oxygen and nutrients to tumoral cells; retains their survival under hypoxic conditions; and induces an immunosuppressive microenvironment. Anti-angiogenesis therapy for high-grade gliomas has long been studied as an adjuvant immunotherapy strategy to overcome tumor growth. In the current review, we discussed the underlying molecular mechanisms contributing to glioblastoma aberrant angiogenesis. Further, we discussed clinical applications of monoclonal antibodies, tyrosine kinase inhibitors, and aptamers as three major subgroups of anti-angiogenic immunotherapeutics and their limitations. Moreover, we reviewed clinical and preclinical applications of small interfering RNAs (siRNAs) as the next-generation anti-angiogenic therapeutics and summarized their potential advantages and limitations. siRNAs may serve as next-generation anti-angiogenic therapeutics for glioma. Additionally, application of nanoparticles as a delivery vehicle could increase their selectivity and lower their off-target effects.

Tumor Drug Concentration and Phosphoproteomic Profiles After Two Weeks of Treatment With Sunitinib in Patients with Newly Diagnosed Glioblastoma

PURPOSE

Tyrosine kinase inhibitors (TKI) have poor efficacy in patients with glioblastoma (GBM). Here, we studied whether this is predominantly due to restricted blood-brain barrier penetration or more to biological characteristics of GBM.

PATIENTS AND METHODS

Tumor drug concentrations of the TKI sunitinib after 2 weeks of preoperative treatment was determined in 5 patients with GBM and compared with its in vitro inhibitory concentration (IC50) in GBM cell lines. In addition, phosphotyrosine (pTyr)-directed mass spectrometry (MS)-based proteomics was performed to evaluate sunitinib-treated versus control GBM tumors.

RESULTS

The median tumor sunitinib concentration of 1.9 μmol/L (range 1.0-3.4) was 10-fold higher than in concurrent plasma, but three times lower than sunitinib IC50s in GBM cell lines (median 5.4 μmol/L, 3.0-8.5; P = 0.01). pTyr-phosphoproteomic profiles of tumor samples from 4 sunitinib-treated versus 7 control patients revealed 108 significantly up- and 23 downregulated (P < 0.05) phosphopeptides for sunitinib treatment, resulting in an EGFR-centered signaling network. Outlier analysis of kinase activities as a potential strategy to identify drug targets in individual tumors identified nine kinases, including MAPK10 and INSR/IGF1R.

CONCLUSIONS

Achieved tumor sunitinib concentrations in patients with GBM are higher than in plasma, but lower than reported for other tumor types and insufficient to significantly inhibit tumor cell growth in vitro. Therefore, alternative TKI dosing to increase intratumoral sunitinib concentrations might improve clinical benefit for patients with GBM. In parallel, a complex profile of kinase activity in GBM was found, supporting the potential of (phospho)proteomic analysis for the identification of targets for (combination) treatment.

Canonical and Non-Canonical Roles of PFKFB3 in Brain Tumors

PFKFB3 is a bifunctional enzyme that modulates and maintains the intracellular concentrations of fructose-2,6-bisphosphate (F2,6-P2), essentially controlling the rate of glycolysis. PFKFB3 is a known activator of glycolytic rewiring in neoplastic cells, including central nervous system (CNS) neoplastic cells. The pathologic regulation of PFKFB3 is invoked via various microenvironmental stimuli and oncogenic signals. Hypoxia is a primary inducer of PFKFB3 transcription via HIF-1alpha. In addition, translational modifications of PFKFB3 are driven by various intracellular signaling pathways that allow PFKFB3 to respond to varying stimuli. PFKFB3 synthesizes F2,6P2 through the phosphorylation of F6P with a donated PO4 group from ATP and has the highest kinase activity of all PFKFB isoenzymes. The intracellular concentration of F2,6P2 in cancers is maintained primarily by PFKFB3 allowing cancer cells to evade glycolytic suppression. PFKFB3 is a primary enzyme responsible for glycolytic tumor metabolic reprogramming. PFKFB3 protein levels are significantly higher in high-grade glioma than in non-pathologic brain tissue or lower grade gliomas, but without relative upregulation of transcript levels. High PFKFB3 expression is linked to poor survival in brain tumors. Solitary or concomitant PFKFB3 inhibition has additionally shown great potential in restoring chemosensitivity and radiosensitivity in treatment-resistant brain tumors. An improved understanding of canonical and non-canonical functions of PFKFB3 could allow for the development of effective combinatorial targeted therapies for brain tumors.

MiR-450a-5p strengthens the drug sensitivity of gefitinib in glioma chemotherapy via regulating autophagy by targeting EGFR

Glioma reported to be refractory to EGFR tyrosine kinase inhibitor is the most common malignant tumor in central nervous system. Our research showed the low expression of miR-450a-5p and high expression of EGFR in glioma tissues. MiR-450a-5p was also observed to synergize with gefitinib to inhibit the proliferation, migration and invasion and induce the apoptosis and autophagy of glioma cells. Furthermore, miR-450a-5p was demonstrated to target 3'UTR of EGFR, and regulated EGFR-induced PI3K/AKT/mTOR signaling pathway. Moreover, the above effects induced by miR-450a-5p in glioma cells were reversed by WIPI1 silencing. The inhibition role of miR-450a-5p on glioma growth was also confirmed in vivo by subcutaneous and intracranial tumor xenografts. Therefore, we conclude that miR-450a-5p synergizes with gefitinib to inhibit the glioma tumorigenesis through inducing autophagy by regulating the EGFR-induced PI3K/AKT/mTOR signaling pathway, thereby enhancing the drug sensitivity of gefitinib.

Driving Neuronal Differentiation through Reversal of an ERK1/2-miR-124-SOX9 Axis Abrogates Glioblastoma Aggressiveness

Identifying cellular programs that drive cancers to be stem-like and treatment resistant is critical to improving outcomes in patients. Here, we demonstrate that constitutive extracellular signal-regulated kinase 1/2 (ERK1/2) activation sustains a stem-like state in glioblastoma (GBM), the most common primary malignant brain tumor. Pharmacological inhibition of ERK1/2 activation restores neurogenesis during murine astrocytoma formation, inducing neuronal differentiation in tumorspheres. Constitutive ERK1/2 activation globally regulates miRNA expression in murine and human GBMs, while neuronal differentiation of GBM tumorspheres following the inhibition of ERK1/2 activation requires the functional expression of miR-124 and the depletion of its target gene SOX9. Overexpression of miR124 depletes SOX9 in vivo and promotes a stem-like-to-neuronal transition, with reduced tumorigenicity and increased radiation sensitivity. Providing a rationale for reports demonstrating miR-124-induced abrogation of GBM aggressiveness, we conclude that reversal of an ERK1/2-miR-124-SOX9 axis induces a neuronal phenotype and that enforcing neuronal differentiation represents a therapeutic strategy to improve outcomes in GBM.

A Chemical Approach to Overcome Tyrosine Kinase Inhibitors Resistance: Learning from Chronic Myeloid Leukemia

BACKGROUND

The possibilities of treatment for oncological diseases are growing enormously in the last decades. Unfortunately, these developments have led to the onset of resistances with regards to the new treatments. This is particularly true if we face with the therapeutic field of Tyrosine Kinase Inhibitors (TKIs). This review gives an overview of possible TKI resistances that can occur during the treatment of an oncologic diesease and available strategies that can be adopted, taking cues from a successful example such as CML.

METHODS

We performed a literature search for peer-reviewed articles using different databases, such as PubMed and Scopus, and exploiting different keywords and different logical operators.

RESULTS

68 papers were included in the review. Twenty-four papers give an overview of the causes of TKIs resistances in the wide oncologic field. The remaining papers deal CML, deeply analysing the TKIs Resistances present in this pathology and the strategies adopted to overcome them.

CONCLUSION

The aim of this review is to furnish an overview and a methodological guideline for the approach and the overcoming of TKIs Resistances.

Identification of GSK3β inhibitor kenpaullone as a temozolomide enhancer against glioblastoma

Cancer stem cells are associated with chemoresistance and rapid recurrence of malignant tumors, including glioblastoma (GBM). Although temozolomide (TMZ) is the most effective drug treatment for GBM, GBM cells acquire resistance and become refractory to TMZ during treatment. Therefore, glioma stem cell (GSC)-targeted therapy and TMZ-enhancing therapy may be effective approaches to improve GBM prognosis. Many drugs that suppress the signaling pathways that maintain GSC or enhance the effects of TMZ have been reported. However, there are no established therapies beyond TMZ treatment currently in use. In this study, we screened drug libraries composed of 1,301 existing drugs using cell viability assays to evaluate effects on GSCs, which led to selection of kenpaullone, a kinase inhibitor, as a TMZ enhancer targeting GSCs. Kenpaullone efficiently suppressed activity of glycogen synthase kinase (GSK) 3β. Combination therapy with kenpaullone and TMZ suppressed stem cell phenotype and viability of both GSCs and glioma cell lines. Combination therapy in mouse models significantly prolonged survival time compared with TMZ monotherapy. Taken together, kenpaullone is a promising drug for treatment of GBM by targeting GSCs and overcoming chemoresistance to TMZ.

WZY-321, a novel evodiamine analog, inhibits glioma cell growth in an autophagy-associated manner

Glioblastoma is one of the most aggressive types of brain tumor. The median survival rate of patients with glioblastoma (World Health Organization grade IV) is <15 months. Therefore, there is an urgent requirement for the development of novel and efficient therapeutic agents against glioma. In previous studies, WZY-321 (10-hydroxy-1-methyl-8,13b-dihydro-5H,7H-benzo[e]benzofuro[2',3':3,4]pyrido[2,1-b][1,3]oxazin-5-one), a novel evodiamine (Evo) analog, was reported to exhibit enhanced pharmacological properties and improved cytotoxicity against a number of human cancer cell lines compared with Evo. In the current study, the anti-proliferative effect of WZY-321 on SHG-44 and SWO-38 glioma cells was further studied, and its mechanism of action investigated. The results indicated that WZY-321 inhibited the proliferation of SHG-44 cells in a dose- and time-dependent manner by enhancing cellular apoptosis and inducing cell cycle arrest at the G2-M phase. Treatment of glioma cells with WZY-321 concomitantly increased the expression levels of microtubule associated protein 1 light chain 3α and Beclin1, indicating enhanced autophagy. Overall, the results of the present study revealed the anti-proliferative potential of WZY-321 in glioma cells, thus providing a possible autophagy-based therapeutic strategy for the treatment of glioblastoma.

Biological basis and clinical study of glycogen synthase kinase- 3β-targeted therapy by drug repositioning for glioblastoma

Background

Glycogen synthase kinase (GSK)-3β has emerged as an appealing therapeutic target for glioblastoma (GBM). Here, we investigated the therapeutic effect of the current approved drugs against GBM via inhibition of GSK3β activity both, in experimental setting and in a clinical study for recurrent GBM patients by repositioning existent drugs in combination with temozolomide (TMZ).

Materials and Methods

Progression-free and overall survival rates were compared between patients with low or high expression of active GSK3β in the primary tumor. GBM cells and a mouse model were examined for the effects of GSK3β-inhibitory drugs, cimetidine, lithium, olanzapine, and valproate. The safety and efficacy of the cocktail of these drugs (CLOVA cocktail) in combination with TMZ were tested in the mouse model and in a clinical study for recurrent GBM patients.

Results

Activation of GSK3β in the tumor inversely correlated with patient survival as an independent prognostic factor. CLOVA cocktail significantly inhibited cell invasion and proliferation. The patients treated with CLOVA cocktail in combination with TMZ showed increased survival compared to the control group treated with TMZ alone.

Conclusions

Repositioning of the GSK3β-inhibitory drugs improved the prognosis of refractory GBM patients with active GSK3β in tumors. Combination of CLOVA cocktail and TMZ is a promising approach for recurrent GBM.

Dactolisib (NVP-BEZ235) toxicity in murine brain tumour models

Background

Glioblastomas (GBMs) are highly malignant brain tumours with a poor prognosis, and current cytotoxic regimens provide only a limited survival benefit. The PI3K/Akt/mTOR pathway has been an attractive target for therapy due to its high activation in GBMs as well as other cancers. The dual pan-PI3K/mTOR kinase inhibitor dactolisib (NVP-BEZ235) is an anti-neoplastic compound currently under investigation. However, little is known about its efficacy in human GBMs. We aimed at evaluating the efficacy of dactolisib in human glioblastoma cells, as well as in murine models carrying human GBM xenografts.

Methods

To assess the effect of dactolisib in vitro, MTS assay, manual cell count, BrdU incorporation and Annexin V staining experiments were used to observe growth and apoptosis. Furthermore, Akt phosphorylation (S473), a downstream target of PI3K, was explored by western blotting. Animal studies utilizing orthotopic xenograft models of glioblastoma were performed in nude rats and NOD/SCID mice to monitor survival benefit or inhibition of tumor growth.

Results

We found that dactolisib in vitro shows excellent dose dependent anti-growth properties and increase in apoptosis. Moreover, dose dependent inhibition of Akt phosphorylation (S473), a downstream effect of PI3K, was observed by western blotting. However, in two independent animal studies utilizing nude rats and NOD/SCID mice in orthotopic xenograft models of glioblastoma, we observed no survival benefit or inhibition of tumour growth. Severe side effects were observed, such as elevated levels of blood glucose and the liver enzyme alanine transaminase (ALT), in addition to diarrhoea, hair loss (alopecia), skin rash and accumulation of saliva in the oral cavity.

Conclusion

Taken together, our results suggest that despite the anti-neoplastic efficacy of dactolisib in glioma treatment in vitro, its utility in vivo is questionable due to toxicity.

Therapeutic control and resistance of the EGFR-driven signaling network in glioblastoma

The alteration of the epidermal growth factor receptor (EGFR)-driven signaling network is a characteristic feature of glioblastomas (GBM), and its inhibition represents a treatment strategy. However, EGFR-targeted interventions have been largely ineffective. Complex perturbations in this system are likely to be central to tumor cells with high adaptive capacity and resistance to therapies. We review key concepts and mechanisms relevant to EGFR-targeted treatment resistance at a systems level. Our understanding of treatment resistance as a systems-level phenomenon is necessary to develop effective therapeutic options for GBM patients. This is allowing us to go beyond the notion of therapeutic targets as single molecular components, into strategies that can weaken cancer signaling robustness and boost inherent network-level vulnerabilities.