Sunitinib targets PDGF-receptor and Flt3 and reduces survival and migration of human meningioma cells

A Review of FDA-Approved Multi-Target Angiogenesis Drugs for Brain Tumor Therapy

Neovascularization is an important process in brain tumor development, invasion and metastasis. Several research studies have indicated that the VEGF signaling target has potential for reducing angiogenesis in brain tumors. However, targeting VEGF signaling has not met the expected efficacy, despite initial enthusiasm. This is partly because tumors cleverly use alternative growth factor pathways, other than VEGF signaling, to restore angiogenesis. Multi-target inhibitors have been developed to inhibit several receptor kinases that play a role in the development of angiogenesis. By simultaneously affecting various receptor kinases, these treatments can potentially obstruct various angiogenic pathways that are involved in brain cancer advancement, often offering a more holistic strategy than treatments focusing on just one kinase. Since 2009, the FDA has approved a number of multi-kinase inhibitors that target angiogenic growth factor receptors (e.g., VEGFR, PDGFR, FGFR, RET, c-KIT, MET, AXL and others) for treatment of malignant diseases, including brain cancer. Here, we present some recent results from the literature regarding the preclinical and clinical effects of these inhibitors on brain tumors.

Exploring the anti-metastatic potential of sunitinib and novel analogs in colorectal cancer: insights into HIF-1α mediated metastasis

Introduction

Colorectal cancer (CRC) is a prevalent malignancy worldwide with high mortality rate. Metastasis, the primary cause of cancer-related deaths, is attributed to various factors including tumor hypoxia. Due to the urgent demand for potent anti-metastatic agents, we aimed to determine the effects of sunitinib and novel analogs on the metastatic behavior of human CRC cells in hypoxic condition for the first time.

Methods

For in silico analyses, pathogenic targets of metastatic CRC were identified, PPI network was constructed and KEGG pathway enrichment analysis was conducted. The expression of HIF1A was evaluated in seven CRC cell lines, and computational modeling was carried out to define the interaction of sunitinib with HIF-1α. For in vitro studies, analogs of sunitinib were synthesized, and cells were assessed for viability, migration, invasion, MMPs activity and gene expression in hypoxic condition.

Results and Discussion

Computational analyses highlighted the importance of HIF-1α as a crucial mediator of metastasis in CRC. Molecular docking and dynamics simulations demonstrated favorable and stable interaction of sunitinib and three novel analogs with HIF-1α PAS-B domain. Volcano plots indicated upregulation of HIF1A in LoVo cells compared to six other CRC cell lines. Findings of in vitro studies revealed considerable inhibitory effects of sunitinib and analogs on LoVo cell migration and invasion in hypoxic condition. Gelatin zymography and qPCR analysis indicated decreased activity of MMP-2 and MMP-9, along with downregulation of EMT transcription factors in hypoxic condition. Current study reports promising anti-metastatic effects of sunitinib and novel analogs on CRC cells, providing foundation for further investigation to combat cancer metastasis.

New clinical trial design in precision medicine: discovery, development and direction

In the era of precision medicine, it has been increasingly recognized that individuals with a certain disease are complex and different from each other. Due to the underestimation of the significant heterogeneity across participants in traditional "one-size-fits-all" trials, patient-centered trials that could provide optimal therapy customization to individuals with specific biomarkers were developed including the basket, umbrella, and platform trial designs under the master protocol framework. In recent years, the successive FDA approval of indications based on biomarker-guided master protocol designs has demonstrated that these new clinical trials are ushering in tremendous opportunities. Despite the rapid increase in the number of basket, umbrella, and platform trials, the current clinical and research understanding of these new trial designs, as compared with traditional trial designs, remains limited. The majority of the research focuses on methodologies, and there is a lack of in-depth insight concerning the underlying biological logic of these new clinical trial designs. Therefore, we provide this comprehensive review of the discovery and development of basket, umbrella, and platform trials and their underlying logic from the perspective of precision medicine. Meanwhile, we discuss future directions on the potential development of these new clinical design in view of the "Precision Pro", "Dynamic Precision", and "Intelligent Precision". This review would assist trial-related researchers to enhance the innovation and feasibility of clinical trial designs by expounding the underlying logic, which be essential to accelerate the progression of precision medicine.

Integrative Analyses of Tumor and Peripheral Biomarkers in the Treatment of Advanced Renal Cell Carcinoma

The phase III JAVELIN Renal 101 trial demonstrated prolonged progression-free survival (PFS) in patients (N = 886) with advanced renal cell carcinoma treated with first-line avelumab + axitinib (A+Ax) versus sunitinib. We report novel findings from integrated analyses of longitudinal blood samples and baseline tumor tissue. PFS was associated with elevated lymphocyte levels in the sunitinib arm and an abundance of innate immune subsets in the A+Ax arm. Treatment with A+Ax led to greater T-cell repertoire modulation and less change in T-cell numbers versus sunitinib. In the A+Ax arm, patients with tumors harboring mutations in ≥2 of 10 previously identified PFS-associated genes (double mutants) had distinct circulating and tumor-infiltrating immunologic profiles versus those with wild-type or single-mutant tumors, suggesting a role for non-T-cell-mediated and non-natural killer cell-mediated mechanisms in double-mutant tumors. We provide evidence for different immunomodulatory mechanisms based on treatment (A+Ax vs. sunitinib) and tumor molecular subtypes.

SIGNIFICANCE

Our findings provide novel insights into the different immunomodulatory mechanisms governing responses in patients treated with avelumab (PD-L1 inhibitor) + axitinib or sunitinib (both VEGF inhibitors), highlighting the contribution of tumor biology to the complexity of the roles and interactions of infiltrating immune cells in response to these treatment regimens. This article is featured in Selected Articles from This Issue, p. 384.

The expression of platelet-derived growth factor and its receptor in canine and feline meningiomas

Feline meningiomas usually have benign biological behavior, while canine and human meningiomas are often classified as grade 2 or 3. Activation of the platelet-derived growth factor (PDGF) and its receptor signal pathway through PDGFβ/Rβ autocrine and paracrine is considered to play an important role in the tumor proliferation and malignant transformation of human meningiomas. However, there have been few studies about the expression of these molecules in canine meningiomas and no studies about their expression in feline meningiomas. We analyzed the PDGFα/Rα and PDGFβ/Rβ expression in canine and feline meningiomas by immunohistochemistry and western blotting. Immunohistochemically, most canine meningiomas showed the expression of PDGFα (42/44; 95.5%), PDGFRα (44/44; 100%) and PDGFRβ (35/44; 79.5%), and a few showed the expression of PDGFβ (8/44; 18.2%). In contrast, feline meningiomas were immunopositive for PDGFRα and PDGFRβ in all cases (14/14; 100%), while no or a few cases expressed PDGFα (0/14; 0%) and PDGFβ (2/14; 14.3%). Western blotting revealed specific bands for PDGFα, PDGFRα and PDGFRβ, but not for PDGFβ in a canine meningioma. In a feline meningioma, specific bands for PDGFRα and PDGFRβ were detected, but not for PDGFα and PDGFβ. These results suggested that canine meningiomas commonly express PDGFα/Rα, and thus autocrine or paracrine PDGFα/Rα signaling may be involved in their initiation and progression. Moreover, PDGF negativity may be related to benign biological behavior and a low histopathological grade in feline meningioma.

Modeling Meningiomas: Optimizing Treatment Approach

Preclinical meningioma models offer a setting to test molecular mechanisms of tumor development and targeted treatment options but historically have been challenging to generate. Few spontaneous tumor models in rodents have been established, but cell culture and in vivo rodent models have emerged along with artificial intelligence, radiomics, and neural networks to differentiate the clinical heterogeneity of meningiomas. We reviewed 127 studies using PRISMA guideline methodology, including laboratory and animal studies, that addressed preclinical modeling. Our evaluation identified that meningioma preclinical models provide valuable molecular insight into disease progression and effective chemotherapeutic and radiation approaches for specific tumor types.

Brain Invasion and Trends in Molecular Research on Meningioma

Meningiomas are the most common primary brain tumors in adults. The treatment of non-benign meningiomas remains a challenging task, and after the publication of the 2021 World Health Organization classification, the importance of molecular biological classification is emerging. In this article, we introduce the mechanisms of brain invasion in atypical meningioma and review the genetic factors involved along with epigenetic regulation. First, it is important to understand the three major steps for brain invasion of meningeal cells: 1) degradation of extracellular matrix by proteases, 2) promotion of tumor cell migration to resident cells by adhesion molecules, and 3) neovascularization and supporting cells by growth factors. Second, the genomic landscape of meningiomas should be analyzed by major categories, such as germline mutations in NF2 and somatic mutations in non-NF2 genes (TRAF7, KLF4, AKT1, SMO, and POLR2A). Finally, epigenetic alterations in meningiomas are being studied, with a focus on DNA methylation, histone modification, and RNA interference. Increasing knowledge of the molecular landscape of meningiomas has allowed the identification of prognostic and predictive markers that can guide therapeutic decision-making processes and the timing of follow-up.

Molecular neuropathology of brain-invasive meningiomas

Invasion of brain tissue by meningiomas has been identified as one key factor for meningioma recurrence. The identification of meningioma tumor tissue surrounded by brain tissue in neurosurgical samples has been touted as a criterion for atypical meningioma (CNS WHO grade 2), but is only rarely seen in the absence of other high-grade features, with brain-invasive otherwise benign (BIOB) meningiomas remaining controversial. While post-surgery irradiation therapy might be initiated in brain-invasive meningiomas to prevent recurrences, specific treatment approaches targeting key molecules involved in the invasive process are not established. Here we have compiled the current knowledge about mechanisms supporting brain tissue invasion by meningiomas and summarize preclinical models studying targeted therapies with potential inhibitory effects.

Sunitinib malate inhibits hemangioma cell growth and migration by suppressing focal adhesion kinase signaling

Sunitinib malate is a small molecule that targets multiple receptor tyrosine kinases and blocks their activity. Receptors targeted by sunitinib are implicated in tumor vascularization and are overexpressed by vascular tumors encountered in infants, namely, hemangiomas. Of note is that there is still no definitive treatment for these commonly occurring tumors of infancy. The purpose of this study was to investigate the effects of sunitinib malate on hemangioma using endothelial cells isolated from a murine model of the neoplasm (sEnd.2). The effects of the drug on cell growth were evaluated using the crystal violet assay and flow cytometry, while the scratch assay was employed to measure cell migration. Proteins associated with cell migration and angiogenesis were detected using western blotting. Sunitinib was investigated further to determine its effects on the production of reactive oxygen species, a parameter associated with the promotion of neovascularization in tumors. The results showed that sunitinib significantly reduced the growth of sEnd.2 cells by causing the cells to accumulate in the sub-G1 phase of the cell cycle, and also induced a significant decrease in the migration of these hemangioma cells (P < 0.05). The western blot assay showed a decrease in the expression of adhesion proteins, focal adhesion kinase and paxillin at IC50 doses, although the expression of cadherin did not change significantly (P < 0.05). In addition, transforming growth factor-β1 (TGF-β1) expression was decreased in sunitinib-treated cells at the same dose. The adhesion proteins as well as TGF-β1 regulate cell movement and have been implicated in tumor progression. Thus, sunitinib malate may have potential in the treatment of hemangiomas.

Receptor-Tyrosine Kinase Inhibitor Ponatinib Inhibits Meningioma Growth In Vitro and In Vivo

To date, there is no standard-of-care systemic therapy for the treatment of aggressive meningiomas. Receptor tyrosine kinases (RTK) are frequently expressed in aggressive meningiomas and are associated with poor survival. Ponatinib is a FDA- and EMA-approved RTK inhibitor and its efficacy in meningioma has not been studied so far. Therefore, we investigated ponatinib as a potential drug candidate against meningioma. Cell viability and cell proliferation of ponatinib-treated meningioma cells were assessed using crystal violet assay, manual counting and BrdU assay. Treated meningioma cell lines were subjected to flow cytometry to evaluate the effects on cell cycle and apoptosis. Meningioma-bearing mice were treated with ponatinib to examine antitumor effects in vivo. qPCR was performed to assess the mRNA levels of tyrosine kinase receptors after ponatinib treatment. Full-length cDNA sequencing was carried out to assess differential gene expression. IC50 values of ponatinib were between 171.2 and 341.9 nM in three meningioma cell lines. Ponatinib induced G0/G1 cell cycle arrest and subsequently led to an accumulation of cells in the subG1-phase. A significant induction of apoptosis was observed in vitro. In vivo, ponatinib inhibited meningioma growth by 72.6%. Mechanistically, this was associated with downregulation of PDGFRA/B and FLT3 mRNA levels, and mitochondrial dysfunction. Taken together, ponatinib is a promising candidate for targeted therapy in the treatment of aggressive meningioma.

Efficacy of decitabine in malignant meningioma cells: relation to promoter demethylation of distinct tumor suppressor and oncogenes and independence from TERT

OBJECTIVE

Chemotherapeutic options for meningiomas refractory to surgery or irradiation are largely unknown. Human telomerase reverse transcriptase (hTERT) promoter methylation with subsequent TERT expression and telomerase activity, key features in oncogenesis, are found in most high-grade meningiomas. Therefore, the authors investigated the impact of the demethylating agent decitabine (5-aza-2'-deoxycytidine) on survival and DNA methylation in meningioma cells.

METHODS

hTERT promoter methylation, telomerase activity, TERT expression, and cell viability and proliferation were investigated prior to and after incubation with decitabine in two benign (HBL-52 and Ben-Men 1) and one malignant (IOMM-Lee) meningioma cell line. The global effects of decitabine on DNA methylation were additionally explored with DNA methylation profiling.

RESULTS

High levels of TERT expression, telomerase activity, and hTERT promoter methylation were found in IOMM-Lee and Ben-Men 1 but not in HBL-52 cells. Decitabine induced a dose-dependent significant decrease of proliferation and viability after incubation with doses from 1 to 10 μM in IOMM-Lee but not in HBL-52 or Ben-Men 1 cells. However, effects in IOMM-Lee cells were not related to TERT expression, telomerase activity, or hTERT promoter methylation. Genome-wide methylation analyses revealed distinct demethylation of 14 DNA regions after drug administration in the decitabine-sensitive IOMM-Lee but not in the decitabine-resistant HBL-52 cells. Differentially methylated regions covered promoter regions of 11 genes, including several oncogenes and tumor suppressor genes that to the authors' knowledge have not yet been described in meningiomas.

CONCLUSIONS

Decitabine decreases proliferation and viability in high-grade but not in benign meningioma cell lines. The effects of decitabine are TERT independent but related to DNA methylation changes of promoters of distinct tumor suppressor genes and oncogenes.

An expanded analysis framework for multivariate GWAS connects inflammatory biomarkers to functional variants and disease

Multivariate methods are known to increase the statistical power to detect associations in the case of shared genetic basis between phenotypes. They have, however, lacked essential analytic tools to follow-up and understand the biology underlying these associations. We developed a novel computational workflow for multivariate GWAS follow-up analyses, including fine-mapping and identification of the subset of traits driving associations (driver traits). Many follow-up tools require univariate regression coefficients which are lacking from multivariate results. Our method overcomes this problem by using Canonical Correlation Analysis to turn each multivariate association into its optimal univariate Linear Combination Phenotype (LCP). This enables an LCP-GWAS, which in turn generates the statistics required for follow-up analyses. We implemented our method on 12 highly correlated inflammatory biomarkers in a Finnish population-based study. Altogether, we identified 11 associations, four of which (F5, ABO, C1orf140 and PDGFRB) were not detected by biomarker-specific analyses. Fine-mapping identified 19 signals within the 11 loci and driver trait analysis determined the traits contributing to the associations. A phenome-wide association study on the 19 representative variants from the signals in 176,899 individuals from the FinnGen study revealed 53 disease associations (p < 1 × 10-4). Several reported pQTLs in the 11 loci provided orthogonal evidence for the biologically relevant functions of the representative variants. Our novel multivariate analysis workflow provides a powerful addition to standard univariate GWAS analyses by enabling multivariate GWAS follow-up and thus promoting the advancement of powerful multivariate methods in genomics.

A Transient Pseudosenescent Secretome Promotes Tumor Growth after Antiangiogenic Therapy Withdrawal

VEGF receptor tyrosine kinase inhibitors (VEGFR TKIs) approved to treat multiple cancer types can promote metastatic disease in certain limited preclinical settings. Here, we show that stopping VEGFR TKI treatment after resistance can lead to rebound tumor growth that is driven by cellular changes resembling senescence-associated secretory phenotypes (SASPs) known to promote cancer progression. A SASP-mimicking antiangiogenic therapy-induced secretome (ATIS) was found to persist during short withdrawal periods, and blockade of known SASP regulators, including mTOR and IL-6, could blunt rebound effects. Critically, senescence hallmarks ultimately reversed after long drug withdrawal periods, suggesting that the transition to a permanent growth-arrested senescent state was incomplete and the hijacking of SASP machinery ultimately transient. These findings may account for the highly diverse and reversible cytokine changes observed in VEGF inhibitor-treated patients, and suggest senescence-targeted therapies ("senotherapeutics")-particularly those that block SASP regulation-may improve outcomes in patients after VEGFR TKI failure.

Downregulation of GRK5 hampers the migration of breast cancer cells

Sunitinib is a multispecific kinase inhibitor and one of its targets is the kinase GRK5, which is regulating a multitude of G protein-coupled receptors (GPCRs). In this study we demonstrate that a decreased GRK5 expression induced by knock-down experiments or sunitinib treatment hampers the migration of cancer cell lines. A proteomic analysis revealed many pathways related to cell migration which were down regulated upon the GRK5 knock-down. Furthermore, we found in MDA-MB-231 breast cancer cells that the inhibition of migration is mediated by the GPCR gastrin releasing peptide receptor (GRPR) leading to a reduced expression of migration regulating downstream targets like CDC42 and ROCK1. An in silico Kaplan Meier analysis revealed that GRK5 and GRPR overexpression reduces the distant metastasis free survival in triple-negative breast cancer (TNBC) patients. Thus, we suggest a novel anti-migratory effect of impaired GRK5 expression which induces a negative feedback loop on GRPR signalling.

Medical management of meningioma in the era of precision medicine

Surgery is curative for most meningiomas, but a minority of these tumors recur and progress after resection. Initial trials of medical therapies for meningioma utilized nonspecific cytotoxic chemotherapies. The presence of hormone receptors on meningioma ushered in trials of hormone-mimicking agents. While these trials expanded clinical understanding of meningioma, they ultimately had limited efficacy in managing aggressive lesions. Subsequent detection of misregulated proteins and genomic aberrancies motivated the study of therapies targeting specific biological disturbances observed in meningioma. These advances led to trials of targeted kinase inhibitors and immunotherapies, as well as combinations of these agents together with chemotherapies. Prospective trials currently recruiting participants are testing a diverse range of medical therapies for meningioma, and some studies now require the presence of a specific protein alteration or genetic mutation as an inclusion criterion. Increasing understanding of the unique and heterogeneous nature of meningiomas will continue to spur the development of novel medical therapies for the arsenal against aggressive tumors.

Evaluation of VEGF, FGF and PDGF and Serum Levels of Inflammatory Cytokines in Patients with Glioma and Meningioma in Southern Iran

BACKGROUND

Meningioma and glioma are common central nervous system tumors. Hypoxic tumor cells secrete angiogenic cytokines, such as vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) that stimulate neovascular formation and inflammatory cytokine, such as TNF-α and IL-1β. We measured these serum levels in patients with glial cell tumors and meningioma.

MATERIALS AND METHODS

This was a case-control study in 2014-2015 on patients diagnosed with meningioma/glioma. All demographic and clinical data were registered. The tumor volume and intraoperative bleeding were recorded. Serum levels of VEGF, PDGF, FGF, TNF-α and IL-1β were measured by ELISA methods.

RESULTS

Ninety-six patients were enrolled in this study, 32 in each group. Patients VEGF level with cranial tumor, glioma/meningioma had increased. VEGF level was highest among grade IV tumors, larger tumors, and in glioblastoma multiform. There was an upsurge in VEGF serum level as glioma grade increased. The highest VEGF levels were seen in parasagittal meningioma. In contrast to VEGF, PDGF was slightly elevated in glial cell tumors, which was significantly elevated in meningioma. Higher PDGF correlated with increased intraoperative bleeding, especially in meningioma cases. Oligodendroglial tumors expressed higher PDGF levels in contrast to other glial tumors. FGF level was not statistically significant. TNF-α and IL-1β expressions were significantly higher in the meningioma and glioma group in comparison to control group.

CONCLUSION

We found increased VEGF and PDGF serum levels in CNS patient's tumor. A different role for PDGF was found in the pathogenesis of neovascularization of meningioma, as well as oligodendroglioma. No significant result was found for FGF. TNF-α and IL-1β can serve as key prognostic biomarker in high-grade glioma and meningioma patients.

SSTR-2 as a potential tumour-specific marker for fluorescence-guided meningioma surgery

BACKGROUND

Meningiomas are the most frequently occurring primary intracranial tumours in adults. Surgical removal can only be curative by complete resection; however surgical access can be challenging due to anatomical localization and local invasion of bone and soft tissues. Several intraoperative techniques have been tried to improve surgical resection, including intraoperative fluorescence guided imaging; however, no meningioma-specific (fluorescent) targeting has been developed yet. Here, we aimed to identify the most promising biomarkers for targeted intra-operative fluorescence guided meningioma surgery.

METHODS

One hundred forty-eight meningioma specimens representing all meningioma grades were analysed using immunohistochemistry (IHC) on tissue microarrays (TMAs) to determine expression patterns of meningioma biomarkers epithelial membrane antigen (EMA), platelet-derived growth factor β (PDGF-β), vascular endothelial growth factor α (VEGF-α), and somatostatin receptor type 2 (SSTR-2). Subsequently, the most promising biomarker was selected based on TArget Selection Criteria (TASC). Marker expression was examined by IHC in 3D cell culture models generated from freshly resected tumour material.

RESULTS

TMA-IHC showed strongest staining for SSTR-2. All cases were positive, with 51.4% strong/diffuse, 30.4% moderate/diffuse and only 18.2% focal/weak staining patterns. All tested biomarkers showed at least weak positivity in all meningiomas, regardless of WHO grade. TASC analysis showed that SSTR-2 was the most promising target for fluorescence guided imaging, with a total score of 21 (out of 22). SSTR-2 expression was determined on original patient tumours and 3D cultures of three established cultures.

CONCLUSIONS

SSTR-2 expression was highly sensitive and specific in all 148 meningiomas, regardless of WHO grade. According to TASC analysis, SSTR-2 is the most promising receptor for meningioma targeting. After establishing in vitro meningioma models, SSTR-2 cell membrane expression was confirmed in two of three meningioma cultures as well. This indicates that specific fluorescence in an experimental setting can be performed for the further development of targeted fluorescence guided meningioma surgery and near-infrared fluorescent tracers targeting SSTR-2.

Ectopic rhabdoid meningioma of the orbit in a child: case report and review of the literature

In August 2016, an 11-year-old boy presented to the authors' institution with a right orbital tumor that was located superotemporally (superolaterally) and adherent to the sclera. The patient's past medical history revealed that he had undergone 2 previous craniotomies elsewhere in June 2008 and July 2010 for a superomedially located orbital lesion that had been histopathologically diagnosed as a neurothekeoma. After the second craniotomy, the patient underwent adjuvant intensity modulated radiotherapy (IMRT) to the right medial orbit. At the authors' institution, total excision of the orbital tumor was performed via an anterior conjunctival orbitotomy. Histopathological examination revealed a rhabdoid meningioma. Review of the histopathology obtained at the time of previous tumor excisions showed that the lesion was misdiagnosed as neurothekeoma and instead represented a meningioma from the beginning. The patient was started on a regimen of oral sunitinib and remained free of recurrence at 1.5 years of follow-up. Ectopic meningioma of the orbit is a rare entity. Rhabdoid meningioma is a rarely seen subtype of meningioma, accounting for 1%-3% of all intracranial meningiomas. To the best of the authors' knowledge, this is the first case of an ectopic orbital rhabdoid meningioma reported in the literature. They suspect that tumor seeding during the previous surgeries might have played a role in the occurrence of the tumor in an orbital location not targeted by IMRT.

Dramatic radiographic response resulting in cerebrospinal fluid rhinorrhea associated with sunitinib therapy in recurrent atypical meningioma: case report

Sunitinib is a multiple tyrosine kinase inhibitor with antiangiogenic, cytostatic, and antimigratory activity for meningiomas. A recent clinical trial of sunitinib for treatment of recurrent Grade II and III meningiomas suggested potential efficacy in this population, but only 2 patients exhibited significant radiographic response with tumor volume reduction. The authors illustrate another such case and discuss a complication related to this dramatic tumor volume reduction in aggressive skull base meningiomas.

The authors describe the case of a 39-year-old woman who had undergone repeat surgical interventions and courses of radiotherapy over the previous 11 years for recurrent cranial and spinal meningiomas. Despite 4 operations over the course of 4 years on her right petroclival meningioma with cavernous sinus and jugular fossa extensions, she had progressive neurological deficits and tumor recurrences. The specimen histology progressed from WHO Grade I initially to Grade II at the time of the third recurrence. The lesion was then irradiated 3 times using stereotactic radiosurgery for further recurrences. More recently, the tumor size increased rapidly on imaging, in association with progressive neurological symptoms arising from brainstem compression and vasogenic edema. Institution of sunitinib therapy yielded a dramatic radiographic response, with marked reduction in the tumor volume and reduction of brainstem vasogenic edema within a few weeks of initiation of treatment. The significant radiographic response of tumor in the clival region was also associated with CSF rhinorrhea from a dural breach created by resolution of the invasive skull base meningioma, which necessitated withholding the sunitinib medication. To address the leak, the authors undertook surgical exploration and transsphenoidal packing using an autologous fat graft and a vascularized pedicled nasoseptal flap. The patient has done well during follow-up of 3 months after packing, with no evidence of recurrent CSF leak, and the medication was subsequently restarted.

Prior clinical data and the dramatic radiographic response in this patient suggest that sunitinib holds promising therapeutic potential in carefully selected patients with recurrent atypical meningiomas where conventional strategies have been exhausted. There is a potential risk of associated CSF rhinorrhea, especially in more invasive skull base lesions showing dramatic radiographic response.

In vitro evaluation of sunitinib loaded bioresorbable microspheres for potential application in arterial chemoembolization

Drug-loadable bioresorbable microspheres (BRMS) are designed for treating hypervascular tumors through chemoembolization, thereby reducing systemic side effects via controllable local delivery. The present study investigated the degradation and loading capability of bioresorbable microspheres with an anti-angiogenic agent, sunitinib, and then evaluated the release profiles in different media (PBS, 10μg/mL and 4mg/mL lysozyme solutions), and tested catheter deliverability as well as potential antiangiogenic effects of the loaded microspheres. The dry weight of the BRMS showed a consistent decrease over the period of incubation in a 10μg/mL lysozyme solution with 61.3% mass remaining on day 21. Sunitinib was loaded efficiently onto the microspheres, with smaller sizes exhibiting a slightly faster loading and release rate. At 2h, the loading percentages were 99.28%, 97.95%, and 94.39% for 100-300, 300-500, and 500-700μm microspheres, respectively. At 8h, the percentage of drug released were 78.4±5.8%, 71.7±0.3%, and 67.0±2.9% for 100-300, 300-500, and 500-700μm microspheres under static medium conditions, respectively. Under replacing-medium conditions, the presence of 10μg/mL lysozyme slightly delayed the drug release while 4mg/mL lysozyme significantly facilitated the drug release from the microspheres as compared with PBS solution. Confocal imaging revealed an even distribution of sunitinib throughout the microspheres. Drug loaded microspheres were delivered through microcatheters smoothly without any clogging. Sunitinib retained its efficacy at reducing the viability of human endothelial cells after elution from the microspheres. Thus, these bioresorbable microspheres are promising for arterial chemoembolization.

A novel multikinase inhibitor R8 exhibits potent inhibition on cancer cells through both apoptosis and autophagic cell death

Chemotherapy is an important treatment for cancer patients, especially for those with unresectable lesions. Targeted therapy of cancer by specific inhibition of aberrant tyrosine kinase activities in cancer cells with chemically synthesized tyrosine kinase inhibitors (TKIs), shows better responses while less side effects than traditional chemotherapeutic drugs. It is common that cancer cells often exhibit deregulation of several tyrosine kinases simultaneously, multikinase TKIs (MKIs) therefore have greater advantages over single-target TKIs. Currently more MKIs are under developing for better efficacy for different types of cancer. In the present work, we evaluated the in vitro therapeutic potential of a novel MKI, namely R8, with comparison to the clinically available MKI Sunitinib. Results showed that R8 has stronger inhibition on six different types of cancer cell lines with lower IC₅₀ than Sunitinib does. Cell cycle analysis showed that R8 induced significant G0/G1 arrest phase of lung cancer A549 and NCI-H226 cells. The inhibition was also confirmed by colony formation and migration assays in both lung cancer cell lines in a dose-dependent manner. R8 could significantly inhibit the phosphorylation of multiple receptor tyrosine kinases (RTKs) included PDGFRβ, VEGFR2, EGFR and C-Kit, leading to the down-regulation of PI3K-Akt-mTOR signaling. Further analysis revealed that R8 treatment induced more significant apoptosis than Sunitinib did, which might be the consequence of the autophagic cell death. In conclusion, this work suggested R8 to be a promising novel anticancer MKI, and provided the basis for further in vivo investigation on its potential in treatment of lung cancer.

Antitumor activity of gemcitabine against high-grade meningioma in vitro and in vivo

Currently, there is no established therapeutic option for high-grade meningioma recurring after surgery and radiotherapy, and few chemotherapeutic agents are in development for the treatment of high-grade meningioma. Here in this study, we screened a panel of chemotherapeutic agents for their possible antitumor activity in high-grade meningioma and discovered that high-grade meningioma cells show a preferential sensitivity to antimetabolites, in particular, to gemcitabine. In vitro, gemcitabine inhibited the growth of high-grade meningioma cells effectively by inducing S-phase arrest and apoptotic cell death. In vivo, systemic gemcitabine chemotherapy suppressed not only tumor initiation but also inhibited the growth and achieved a long-term control of established tumors in xenograft models of high-grade meningioma. Histological analysis indicated that systemic gemcitabine blocks cell cycle progression and promotes apoptotic cell death in tumor cells in vivo. Together, our data demonstrate that gemcitabine exerts potent antitumor activity against high-grade meningioma through cytostatic and cytotoxic mechanisms. We therefore propose gemcitabine is a promising chemotherapeutic agent that warrants further investigation as a treatment option for high-grade meningioma.

Platelet-Derived Growth Factor BB Influences Muscle Regeneration in Duchenne Muscle Dystrophy

Duchenne muscular dystrophy (DMD) is characterized by a progressive loss of muscle fibers, and their substitution by fibrotic and adipose tissue. Many factors contribute to this process, but the molecular pathways related to regeneration and degeneration of muscle are not completely known. Platelet-derived growth factor (PDGF)-BB belongs to a family of growth factors that regulate proliferation, migration, and differentiation of mesenchymal cells. The role of PDGF-BB in muscle regeneration in humans has not been studied. We analyzed the expression of PDGF-BB in muscle biopsy samples from controls and patients with DMD. We performed in vitro experiments to understand the effects of PDGF-BB on myoblasts involved in the pathophysiology of muscular dystrophies and confirmed our results in vivo by treating the mdx murine model of DMD with repeated i.m. injections of PDGF-BB. We observed that regenerating and necrotic muscle fibers in muscle biopsy samples from DMD patients expressed PDGF-BB. In vitro, PDGF-BB attracted myoblasts and activated their proliferation. Analysis of muscles from the animals treated with PDGF-BB showed an increased population of satellite cells and an increase in the number of regenerative fibers, with a reduction in inflammatory infiltrates, compared with those in vehicle-treated mice. Based on our results, PDGF-BB may play a protective role in muscular dystrophies by enhancing muscle regeneration through activation of satellite cell proliferation and migration.

Receptor tyrosine kinase inhibition by regorafenib/sorafenib inhibits growth and invasion of meningioma cells

Systemic chemotherapeutic treatment for unresectable and/or aggressive meningiomas is still unsatisfying. PDGF receptor (PDGFR)-mediated activation of mitogenic signalling has been shown to be active in meningiomas. Therefore, we evaluate in vitro and in vivo the effects of inhibiting PDGFR using the clinically well-characterised tyrosine kinase inhibitors sorafenib or regorafenib in meningioma models. IOMM-Lee meningioma cells were used to assess cytotoxic effects, inhibition of proliferation, induction of apoptosis, as well as inhibition of migration and motility by sorafenib and regorafenib. Using an orthotopic mouse xenograft model, growth inhibition as monitored by magnetic resonance imaging, and overall survival of sorafenib- or regorafenib-treated mice compared with control animals was determined. Treatment of malignant IOMM-Lee cells resulted in significantly reduced cell survival and induction of apoptosis following regorafenib and sorafenib treatment. Western blots showed that both drugs target phosphorylation of p44/42 ERK via downregulation of the PDGFR. Both drugs additionally showed significant inhibition of cell motility and invasion. In vivo, mice with orthotopic meningioma xenografts showed a reduced volume (n.s.) of signal enhancement in MRI (mainly tumour) following sorafenib and regorafenib treatment. This was translated in a significantly increased overall survival time (p ≤ 0.05) for regorafenib-treated mice. Analyses of in vivo-grown tumours demonstrated again reduced PDGFR expression and expression/phosphorylation of p44/42. Sorafenib and regorafenib show antitumour activity in vitro and in vivo by targeting PDGFR and p44/42 ERK signalling.

Brain tumors - other treatment modalities

Management of tumors of the central nervous system is challenging for clinicians for various reasons, including complex diagnostic procedures, limited penetration of drugs into brain tissue, and the prerequisite to preserve brain function in any case of therapeutic intervention. Therapeutic success is dependent on the efforts, skills, and cooperation of involved specialists and disciplines. Knowledge and ability to apply adequate therapeutic modalities in an interdisciplinary approach in due time are crucial, necessitating coordination of diagnostic procedures and therapeutic interventions by means of multidisciplinary brain tumor boards. In this chapter we present in brief the essential current standards and future perspectives for therapy modalities that complement surgery of brain tumors.

PDGF activation in PGDS-positive arachnoid cells induces meningioma formation in mice promoting tumor progression in combination with Nf2 and Cdkn2ab loss

The role of PDGF-B and its receptor in meningeal tumorigenesis is not clear. We investigated the role of PDGF-B in mouse meningioma development by generating autocrine stimulation of the arachnoid through the platelet-derived growth factor receptor (PDGFR) using the RCAStv-a system. To specifically target arachnoid cells, the cells of origin of meningioma, we generated the PGDStv-a mouse (Prostaglandin D synthase). Forced expression of PDGF-B in arachnoid cells in vivo induced the formation of Grade I meningiomas in 27% of mice by 8 months of age. In vitro, PDGF-B overexpression in PGDS-positive arachnoid cells lead to increased proliferation.We found a correlation of PDGFR-B expression and NF2 inactivation in a cohort of human meningiomas, and we showed that, in mice, Nf2 loss and PDGF over-expression in arachnoid cells induced meningioma malignant transformation, with 40% of Grade II meningiomas. In these mice, additional loss of Cdkn2ab resulted in a higher incidence of malignant meningiomas with 60% of Grade II and 30% of Grade III meningiomas. These data suggest that chronic autocrine PDGF signaling can promote proliferation of arachnoid cells and is potentially sufficient to induce meningiomagenesis. Loss of Nf2 and Cdkn2ab have synergistic effects with PDGF-B overexpression promoting meningioma malignant transformation.

Prostaglandin E2 promotes M2 polarization of macrophages via a cAMP/CREB signaling pathway and deactivates granulocytes in teleost fish

The profile of prostaglandin (PG) production is determined by the differential expression of the enzymes involved in their production and degradation. Although the production of PGE2 by fish leukocytes has been relatively well studied in several fish species, knowledge of how its production is regulated, its biological activities and the signaling pathways activated by this PG is scant or even contradictory. In this work we show that in the teleost fish gilthead seabream (Sparus aurata L.) macrophages regulate PGE2 release mainly by inducing the expression of the genes encoding the enzymes responsible for its synthesis, while acidophilic granulocytes (AGs) not only induce these genes quickly after activation but also inhibit the expression of the genes encoding the enzymes responsible for PGE2 degradation at later time points. In addition, treatment of macrophages with PGE2 promoted their M2 polarization, which is characterized by high expression levels of interleukin-10, mannose-receptor c-type 1 and arginase 2 genes. In sharp contrast, PGE2 promoted the deactivation of AGs, since it decreased the production of reactive oxygen species and the expression of genes encoding pro-inflammatory cytokines. These differences are the result of the alternative signaling pathways used by PGE2 in macrophages and AGs, a cAMP/CREB signaling pathway operating in macrophages, but not in AGs, downstream of PGE2. Our data identify for the first time a role for professional phagocyte-derived-PGE2 in the resolution of inflammation in fish and highlight key differences in the PGE2 signaling pathway in macrophages and granulocytes.

Role of FLT3 in the proliferation and aggressiveness of hepatocellular carcinoma

BACKGROUND/AIM

Previously we showed that Fms-like tyrosine kinase (FLT3) changes its cellular localization upon partial hepatectomy, suggesting a role in liver regeneration. FLT3 was also shown to play an important function in cellular proliferation and activation of PI3K and Ras. Thus, we aimed to investigate the role of FLT3 in hepatocellular tumorigenesis utilizing in vitro and in vivo models.

MATERIALS AND METHODS

We used Snu398 cells that express FLT3. We investigated these cells' in vitro proliferation and invasion abilities by treatment with the FLT3 inhibitor K-252a or by knocking-down with FLT3 shRNA,. Furthermore, the effect of blocking FLT3 activity and expression during in vivo tumorigenesis was assessed with xenograft models.

RESULTS

After K-252a treatment or stable knock-down, these cells' proliferation and migration abilities were highly diminished in vitro. In addition, significant diminution in tumorigenicity of Snu398 cells was also obtained in vivo. When FLT3 knocked-down Snu398 cells were injected into nude mice, we did not detect αSMA expression in these tumors, suggesting a role for FLT3 in in vivo invasiveness.

CONCLUSION

Our data provided evidence that FLT3 has a crucial role both in hepatocarcinogenesis and its invasiveness. Therefore, targeting FLT3 and/or its activity may be a promising tool for combating hepatocellular carcinomas.

Targeting the Sonic Hedgehog Signaling Pathway: Review of Smoothened and GLI Inhibitors

The sonic hedgehog (Shh) signaling pathway is a major regulator of cell differentiation, cell proliferation, and tissue polarity. Aberrant activation of the Shh pathway has been shown in a variety of human cancers, including, basal cell carcinoma, malignant gliomas, medulloblastoma, leukemias, and cancers of the breast, lung, pancreas, and prostate. Tumorigenesis, tumor progression and therapeutic response have all been shown to be impacted by the Shh signaling pathway. Downstream effectors of the Shh pathway include smoothened (SMO) and glioma-associated oncogene homolog (GLI) family of zinc finger transcription factors. Both are regarded as important targets for cancer therapeutics. While most efforts have been devoted towards pharmacologically targeting SMO, developing GLI-targeted approach has its merit because of the fact that GLI proteins can be activated by both Shh ligand-dependent and -independent mechanisms. To date, two SMO inhibitors (LDE225/Sonidegib and GDC-0449/Vismodegib) have received FDA approval for treating basal cell carcinoma while many clinical trials are being conducted to evaluate the efficacy of this exciting class of targeted therapy in a variety of cancers. In this review, we provide an overview of the biology of the Shh pathway and then detail the current landscape of the Shh-SMO-GLI pathway inhibitors including those in preclinical studies and clinical trials.

Enhanced Sensitivity to Sunitinib by Inhibition of Akt1 Expression in Human Castration-resistant Prostate Cancer PC3 Cells Both In Vitro and In Vivo

OBJECTIVE

To investigate whether antitumor activity of sunitinib is enhanced by silencing Akt1 in a human castration-resistant prostate cancer PC3 model.

MATERIALS AND METHODS

We initially established PC3 in which the expression vector containing a short hairpin ribonucleic acid targeting Akt1 was introduced (PC3/sh-Akt1). Changes in various phenotypes of PC3/sh-Akt1 after treatment with sunitinib were compared with those of PC3 transfected with control vector alone (PC3/C) both in vitro and in vivo.

RESULTS

When cultured in the standard medium, in vitro growth of PC3/sh-Akt1 was almost similar to that of PC3/C. However, compared with PC3/C, PC3/sh-Akt1 showed a significantly higher sensitivity to sunitinib, accompanying impaired phosphorylation of p44/42 mitogen-activated protein kinase, downregulation of Bcl-2, and upregulation of Bax. In addition, treatment with sunitinib significantly suppressed the migration ability of PC3/sh-Akt1 compared with that of PC3/C. In vivo, administration of sunitinib induced the significantly marked growth inhibition of PC3/sh-Akt1 compared with that of PC3/C, and apoptotic index in PC3/sh-Akt1 tumor in mice treated with sunitinib was significantly greater than that in PC3/C tumor.

CONCLUSION

Combined treatment with Akt1 inhibitor and sunitinib could be a promising therapeutic approach for men with castration-resistant prostate cancer.

The Role of Mifepristone in Meningiomas Management: A Systematic Review of the Literature

OBJECTIVES

We performed a systematic literature review to analyze the clinical application and the safety of mifepristone, a prominent antiprogesterone agent, in meningioma patients.

MATERIALS AND METHODS

A systematic search was performed through Medline, Cochrane, and clinicaltrials.gov databases from 1960 to 2014. Study Selection. Studies were selected through a PICO approach. Population was meningioma patients, meningioma cells cultures, and animal models. Intervention was mifepristone administration. Control was placebo administration or any other drug tested. Outcomes were clinical and radiological responsiveness, safety profile, and cell growth inhibition.

RESULTS

A total of 7 preclinical and 6 clinical studies and one abstract were included. Encouraging results were found in preclinical studies. Concerning clinical studies, the response rate to mifepristone in terms of radiological regression and symptomatic improvement/stability in patients with inoperable meningioma was low. In meningiomatosis, favorable preliminary results were recorded. The safety profile was good. Limitations were as follows. The tumoral expression of progesterone receptors was not analyzed systematically in every study considered.

CONCLUSIONS

No clear evidence exists to recommend mifepristone in inoperable meningiomas. Preliminary encouraging results were found in diffuse meningiomatosis. Mifepristone is a well-tolerated treatment. Patients' selection and hormonal profile analysis in meningiomas are fundamental for a better understanding of its benefit. Multicenter placebo-controlled trials are required.

Computer aided drug discovery of highly ligand efficient, low molecular weight imidazopyridine analogs as FLT3 inhibitors

The FLT3 kinase represents an attractive target to effectively treat AML. Unfortunately, no FLT3 targeted therapeutic is currently approved. In line with our continued interests in treating kinase related disease for anti-FLT3 mutant activity, we utilized pioneering synthetic methodology in combination with computer aided drug discovery and identified low molecular weight, highly ligand efficient, FLT3 kinase inhibitors. Compounds were analyzed for biochemical inhibition, their ability to selectively inhibit cell proliferation, for FLT3 mutant activity, and preliminary aqueous solubility. Validated hits were discovered that can serve as starting platforms for lead candidates.

Molecular genetics of meningiomas: Building the roadmap towards personalized therapy

New advances have recently been made in the field of molecular genetics and mouse modeling of meningiomas, opening new perspectives for future treatments. Recent genome-wide genotyping and exome sequencing studies have confirmed the pivotal role of NF2 in meningioma tumorigenesis, concerning roughly half of the tumors, and unraveled new mutations in non-NF2 meningiomas concerning AKT1, SMO, KLF4 and TRAF7. The molecular mechanisms underlying tumorigenesis of high histological grades have been progressively deciphered with the recent discovery of TERT promoter mutations in progressing tumors. A better understanding of the genetics and clinical behavior of high-grade meningiomas is mandatory in order to better design future clinical trials. New genetically engineered mouse models of benign and histologically aggressive meningioma represent a substantial resource for the establishment of relevant pre-clinical trials. By studying the mechanisms underlying these new tumorigenesis pathways and the corresponding mouse models, we should be able to offer personalized chemotherapy to patients with surgery- and radiation-refractory meningiomas in the near future.

Re-evaluation of cytostatic therapies for meningiomas in vitro

PURPOSE

The purpose was to re-evaluate in cell culture models the therapeutic usefulness of some discussed chemotherapies or targeted therapies for meningiomas with a special emphasis on the role of the neurofibromatosis type 2 (NF2) tumor suppressor, which had been neglected so far. In addition, the study intended to evaluate a potential benefit from a treatment with drugs which are well established in other fields of medicine and have been linked recently with tumor disease by epidemiological studies.

METHODS

Meningioma cell lines corresponding to various subtypes and pairs of syngenic meningioma cell lines with or without shRNA-induced NF2 knockdown were analyzed for their dose-dependent response to the drugs in microtiter tetrazolium assays, BrdU assays and for selected cases in ELISAs measuring nucleosome liberation to specifically separate cell death from pure inhibition of cell proliferation.

RESULTS

We confirmed a moderate efficacy of hydroxyurea (HU) in clinically relevant concentrations. Under appropriate dosing, we neither detected major responses to the alkylating compound temozolomide nor to various drugs targeting membrane receptors or enzymes (tamoxifen, erlotinib, mifepristone, losartan, metformin and verapamil). Only concentrations far beyond achievable serum levels generated significant effects with the exception of losartan, which showed no effects at all. Chemosensitivity varied markedly among meningioma cell lines. Importantly, cells with NF2 loss exhibited a significantly higher induction of cell death by HU.

CONCLUSIONS

Alternative chemotherapeutic or targeted approaches besides HU have still to be evaluated in further studies, and the role of NF2 must be taken into account.

High-grade meningiomas: new avenues for drug treatment?

PURPOSE OF REVIEW

For standard first-line treatment of high-grade meningiomas, surgical resection and radiotherapy are regarded as standard of care. In the recurrent setting after exhaustion of all local treatment options, no effective therapies are known and several drugs have failed to show efficacy, but novel compounds may offer hope for better disease control.

RECENT FINDINGS

Upregulation of proangiogenic molecules and dysregulation of some signaling pathways such as the platelet-derived growth factor and mammalian target of rapamycin are recurrently found in high-grade meningiomas. Furthermore, in-vitro studies and single patient experience indicate that trabectedin may be an effective therapy in this tumor type. Unfortunately, so far there is a lack of conclusive clinical trials to draw definite conclusions of efficacy of these approaches.

SUMMARY

There remains a significant unmet need for defining the role of medical therapy in recurrent high-grade meningioma, and more basic research and multicentric well designed trials are needed in this rare and devastating tumor type. Potentially promising novel therapeutics include antiangiogenic drugs, molecular inhibitors of signaling cascades, immunotherapeutics or trabectedin. However, more basic research is required to identify more promising drug targets.

VIDEO ABSTRACT AVAILABLE

See the Video Supplementary Digital Content 1 (http://links.lww.com/CONR/A22).

Peptide-based inhibition of the HOXA9/PBX interaction retards the growth of human meningioma

BACKGROUND

Meningiomas are the most common type of intracranial tumor, accounting for between 24 and 30 % of primary intracranial tumors. Thus far, no biomarkers exist to reliably predict the clinical outcome of meningiomas. A previous genome-wide methylation analysis revealed that HOXA9 is one of the most functionally relevant biomarkers. In this study, we have examined whether HOXA9 is a potential therapeutic target in meningiomas, using HXR9, a peptide inhibitor of the interaction between HOXA9 and its cofactor PBX.

METHODS

We determined the expression level of HOXA9 in human meningiomas, meningioma cell lines, and normal brain tissue. Meningioma in culture and in subcutaneous tumors was treated with HXR9. We also examined the disruption of HOXA9/PBX dimers.

RESULTS

We first confirmed that HOXA9 is highly expressed in meningiomas, but not in normal brain tissue. The HXR9 peptide blocks the binding of HOXA9 to PBX, leading to an alteration of DNA binding, and subsequent regulation of their target genes. HXR9 markedly inhibited the growth of meningioma cells and subcutaneous meningeal tumors.

CONCLUSION

There is no effective chemotherapy for meningiomas at present, and targeting the HOXA9/PBX interaction may represent a novel treatment option for this disease.

Enhancement of Lymphangiogenesis In Vitro via the Regulations of HIF-1α Expression and Nuclear Translocation by Deoxyshikonin

The objectives of this study were to determine the effects of deoxyshikonin on lymphangiogenesis. Deoxyshikonin enhanced the ability of human dermal lymphatic microvascular endothelial cells (HMVEC-dLy) to undergo time-dependent in vitro cord formation. Interestingly, an opposite result was observed in cells treated with shikonin. The increased cord formation ability following deoxyshikonin treatment correlated with increased VEGF-C mRNA expression to higher levels than seen for VEGF-A and VEGF-D mRNA expression. We also found that deoxyshikonin regulated cord formation of HMVEC-dLy by increasing the HIF-1α mRNA level, HIF-1α protein level, and the accumulation of HIF-1α in the nucleus. Knockdown of the HIF-1α gene by transfection with siHIF-1α decreased VEGF-C mRNA expression and cord formation ability in HMVEC-dLy. Deoxyshikonin treatment could not recover VEGF-C mRNA expression and cord formation ability in HIF-1α knockdown cells. This indicated that deoxyshikonin induction of VEGF-C mRNA expression and cord formation in HMVEC-dLy on Matrigel occurred mainly via HIF-1α regulation. We also found that deoxyshikonin promoted wound healing in vitro by the induction of HMVEC-dLy migration into the wound gap. This study describes a new effect of deoxyshikonin, namely, the promotion of cord formation by human endothelial cells via the regulation of HIF-1α. The findings suggest that deoxyshikonin may be a new drug candidate for wound healing and treatment of lymphatic diseases.

mTORC1 inhibitors suppress meningioma growth in mouse models

PURPOSE

To evaluate the mTORC1 (mammalian target of rapamycin complex 1) pathway in meningiomas and to explore mTORC1 as a therapeutic target in meningioma cell lines and mouse models.

EXPERIMENTAL DESIGN

Tissue microarrays (53 meningiomas of all WHO grades) were stained for phosphorylated polypeptides of mTOR, Akt, and the mTORC1 targets 4EBP1 and p70S6K, the latter being the consensus marker for mTORC1 activity. Expression of proteins and mRNAs was assessed by Western blotting and real-time PCR in 25 tumors. Cell lines Ben-Men-1 (benign), IOMM-Lee and KT21 (malignant), and pairs of merlin-positive or -negative meningioma cells were used to assess sensitivity toward mTORC1 inhibitors in methyl-tetrazolium and bromodeoxyuridine (BrdUrd) assays. The effect of temsirolimus (20 mg/kg daily) on tumor weight or MRI-estimated tumor volume was tested by treatment of eight nude mice (vs. 7 controls) carrying subcutaneous IOMM-Lee xenografts, or of eight (5) mice xenotransplanted intracranially with IOMM-Lee (KT21) cells in comparison to eight (5) untreated controls.

RESULTS

All components of the mTORC1 pathway were expressed and activated in meningiomas, independent of their WHO grade. A significant dosage-dependent growth inhibition by temsirolimus and everolimus was observed in all cell lines. It was slightly diminished by merlin loss. In the orthotopic and subcutaneous xenograft models, temsirolimus treatment resulted in about 70% growth reduction of tumors (P < 0.01), which was paralleled by reduction of Ki67 mitotic index (P < 0.05) and reduction of mTORC1 activity (p70S6K phosphorylation) within the tumors.

CONCLUSION

mTORC1 inhibitors suppress meningioma growth in mouse models, although the present study did not measure survival.

Emerging roles of PDGF-D in EMT progression during tumorigenesis

Platelet-derived growth factor-D (PDGF-D) signaling pathway has been reported to be involved in regulating various cellular processes, such as cell growth, apoptotic cell death, migration, invasion, angiogenesis and metastasis. Recently, multiple studies have shown that PDGF-D plays a critical role in governing epithelial-to-mesenchymal transition (EMT), although the underlying mechanism of PDGF-D-mediated acquisition of EMT is largely unclear. Therefore, this mini review will discuss recent advances in our understanding of the role of PDGF-D in the acquisition of EMT during tumorigenesis. Furthermore, we will summarize the function of chemical inhibitors and natural compounds that are known to inactivate PDGF-D signaling pathway, which leads to the reversal of EMT. In summary, inactivation of PDGF-D could be a novel strategy for achieving better treatment outcome of patients inflicted with cancers.