Evaluation of In Vitro Activity of the Class I PI3K Inhibitor Buparlisib (BKM120) in Pediatric Bone and Soft Tissue Sarcomas

Roles of phosphatidylinositol-3-kinases signaling pathway in inflammation-related cancer: Impact of rs10889677 variant and buparlisib in colitis-associated cancer

BACKGROUND

Phosphatidylinositol-3-kinases (PI3K) is a well-known route in inflammation-related cancer. Recent discovery on PI3K-related genes revealed a potential variant that links ulcerative colitis (UC) and colorectal cancer (CRC) with colitis-associated cancer (CAC). PI3K/AKT pathway has been recommended as a potential additional therapeutic option for CRC due to its substantial role in modifying cellular processes. Buparlisib is a pan-class I PI3K inhibitor previously shown to reduce tumor growth.

AIM

To investigate the regulation of rs10889677 and the role of buparlisib in the PI3K signaling pathway in CAC pathogenesis.

METHODS

Genomic DNA from 32 colonic samples, including CAC (n = 7), UC (n = 10) and CRC (n = 15), was sequenced for the rs10889677 mutation. The mutant and wildtype fragments were amplified and cloned in the pmirGLO vector. The luciferase activity of cloned vectors was assessed after transfection into the HT29 cell line. CAC mice were induced by a mixture of a single azoxymethane injection and three cycles of dextran sulphate sodium, then buparlisib was administered after 14 d. The excised colon was subjected to immunohistochemistry for Ki67 and Cleaved-caspase-3 markers and quantitative real-time polymerase chain reaction analysis for Pdk1 and Sgk2.

RESULTS

Luciferase activity decreased by 2.07-fold in the rs10889677 mutant, confirming the hypothesis that the variant disrupted miRNA binding sites, which led to an increase in IL23R expression and the activation of the PI3K signaling pathway. Furthermore, CAC-induced mice had a significantly higher disease activity index (P < 0.05). Buparlisib treatment significantly decreased mean weight loss in CAC-induced mice (P < 0.05), reduced the percentage of proliferating cells by 5%, and increased the number of apoptotic cells. The treatment also caused a downward trend of Pdk1 expression and significantly decreased Sgk2 expression.

CONCLUSION

Our findings suggested that the rs10889677 variant as a critical initiator of the PI3K signaling pathway, and buparlisib had the ability to prevent PI3K-non-AKT activation in the pathophysiology of CAC.

Combination of Genomic Landsscape and 3D Culture Functional Assays Bridges Sarcoma Phenotype to Target and Immunotherapy

Genomic-based precision medicine has not only improved tumour therapy but has also shown its weaknesses. Genomic profiling and mutation analysis have identified alterations that play a major role in sarcoma pathogenesis and evolution. However, they have not been sufficient in predicting tumour vulnerability and advancing treatment. The relative rarity of sarcomas and the genetic heterogeneity between subtypes also stand in the way of gaining statistically significant results from clinical trials. Personalized three-dimensional tumour models that reflect the specific histologic subtype are emerging as functional assays to test anticancer drugs, complementing genomic screening. Here, we provide an overview of current target therapy for sarcomas and discuss functional assays based on 3D models that, by recapitulating the molecular pathways and tumour microenvironment, may predict patient response to treatments. This approach opens new avenues to improve precision medicine when genomic and pathway alterations are not sufficient to guide the choice of the most promising treatment. Furthermore, we discuss the aspects of the 3D culture assays that need to be improved, such as the standardisation of growth conditions and the definition of in vitro responses that can be used as a cut-off for clinical implementation.

Potential drug-drug interactions with mitogen-activated protein kinase (MEK) inhibitors used to treat melanoma

INTRODUCTION

The management of patients with BRAF-mutated advanced melanoma who are undergoing targeted therapy with MEK inhibitors can be complicated by the co-administration of multiple medications, which can give rise to drug-drug interactions of clinical significance.

COVERED AREAS

Our review presents a comprehensive analysis of the pharmacokinetic and pharmacodynamic interactions of the three approved for advanced melanoma MEK inhibitor drugs - binimetinib, cobimetinib, and trametinib. MEDLINE (PubMed) was utilized for the literature search, comprising clinical studies, observational studies, and preclinical research. The review discusses the impact of these interactions on efficacy and safety of the treatments and differentiates between interactions supported by pharmacokinetic or pharmacodynamic mechanisms, those encountered in clinical practice, and those observed in preclinical studies.

EXPERT OPINION

Physicians should be aware about potential benefits, but also increased toxicity caused by drug interactions between MEK inhibitors and other drugs in the management of patients with metastatic melanoma.

Non-squamous Laryngeal Cancer

The pathology of non-squamous carcinoma of the larynx is broad and there is a wide differential diagnosis. The most common presenting symptoms for laryngeal malignancies, both squamous and non-squamous, are hoarseness and dyspnea. Presentation with persistent or worsening symptoms and a submucosal lesion should raise suspicion for a non-squamous malignancy of the larynx. Accurate histology determines the most appropriate treatment and has an impact on prognosis.

The Cytotoxic Effect of Curcumin in Rhabdomyosarcoma Is Associated with the Modulation of AMPK, AKT/mTOR, STAT, and p53 Signaling

Approximately 7% of cancers arising in children and 1% of those arising in adults are soft tissue sarcomas (STS). Of these malignancies, rhabdomyosarcoma (RMS) is the most common. RMS survival rates using current therapeutic protocols have remained largely unchanged in the past decade. Thus, it is imperative that the main molecular drivers in RMS tumorigenesis are defined so that more precise, effective, and less toxic therapies can be designed. Curcumin, a common herbal supplement derived from plants of the Curcuma longa species, has an exceptionally low dietary biotoxicity profile and has demonstrated anti-tumorigenic benefits in vitro. In this study, the anti-tumorigenic activity of curcumin was assessed in rhabdomyosarcoma cell lines and used to identify the major pathways responsible for curcumin's anti-tumorigenic effects. Curcumin treatment resulted in cell cycle arrest, inhibited cell migration and colony forming potential, and induced apoptotic cell death. Proteome profiler array analysis demonstrated that curcumin treatment primarily influenced flux through the AKT-mammalian target of rapamycin (mTOR), signal transducer and activator of transcription (STAT), AMP-dependent kinase (AMPK), and p53 associated pathways in a rhabdomyosarcoma subtype-specific manner. Thus, the strategic, combinational therapeutic targeting of these pathways may present the best option to treat this group of tumors.

Combined Treatment with PI3K Inhibitors BYL-719 and CAL-101 Is a Promising Antiproliferative Strategy in Human Rhabdomyosarcoma Cells

Rhabdomyosarcoma (RMS) is a highly malignant and metastatic pediatric cancer arising from skeletal muscle myogenic progenitors. Recent studies have shown an important role for AKT signaling in RMS progression. Aberrant activation of the PI3K/AKT axis is one of the most frequent events occurring in human cancers and serves to disconnect the control of cell growth, survival, and metabolism from exogenous growth stimuli. In the study reported here, a panel of five compounds targeting the catalytic subunits of the four class I PI3K isoforms (p110α, BYL-719 inhibitor; p110β, TGX-221 inhibitor; p110γ, CZC24832; p110δ, CAL-101 inhibitor) and the dual p110α/p110δ, AZD8835 inhibitor, were tested on the RMS cell lines RD, A204, and SJCRH30. Cytotoxicity, cell cycle, apoptosis, and the activation of downstream targets were analyzed. Of the individual inhibitors, BYL-719 demonstrated the most anti-tumorgenic properties. BYL-719 treatment resulted in G1/G0 phase cell cycle arrest and apoptosis. When combined with CAL-101, BYL-719 decreased cell viability and induced apoptosis in a synergistic manner, equaling or surpassing results achieved with AZD8835. In conclusion, our findings indicate that BYL-719, either alone or in combination with the p110δ inhibitor, CAL-101, could represent an efficient treatment for human rhabdomyosarcoma presenting with aberrant upregulation of the PI3K signaling pathway.

Targeting the IGF/PI3K/mTOR Pathway and AXL/YAP1/TAZ pathways in Primary Bone Cancer

Primary bone cancers (PBC) belong to the family of mesenchymal tumors classified based on their cellular origin, extracellular matrix, genetic regulation, and epigenetic modification. The three major PBC types, Ewing sarcoma, osteosarcoma, and chondrosarcoma, are frequently aggressive tumors, highly metastatic, and typically occur in children and young adults. Despite their distinct origins and pathogenesis, these sarcoma subtypes rely upon common signaling pathways to promote tumor progression, metastasis, and survival. The IGF/PI3K/mTOR and AXL/YAP/TAZ pathways, in particular, have gained significant attention recently given their ties to oncogenesis, cell fate and differentiation, metastasis, and drug resistance. Naturally, these pathways – and their protein constituents – have caught the eye of the pharmaceutical industry, and a wide array of small molecule inhibitors and antibody drug-conjugates have emerged. Here, we review how the IGF/PI3K/mTOR and AXL/YAP/TAZ pathways promote PBC and highlight the drug candidates under clinical trial investigation.

MEK inhibition preferentially suppresses anchorage-independent growth in osteosarcoma cells and decreases tumors in vivo

Osteosarcoma is the most common high-grade malignancy of bone, and novel therapeutic options are urgently required. Previously, we developed mouse osteosarcoma AXT cells that can proliferate both under adherent and nonadherent conditions. Based on metabolite levels, nonadherent conditions were more similar to the in vivo environment than adherent conditions. A drug screen identified MEK inhibitors, including trametinib, that preferentially decreased the viability of nonadherent AXT cells. Trametinib inhibited the cell cycle and induced apoptosis in AXT cells, and both effects were stronger under nonadherent conditions. Trametinib also potently decreased viability in U2OS cells, but its effects were less prominent in MG63 or Saos2 cells. By contrast, MG63 and Saos2 cells were more sensitive to PI3K inhibition than AXT or U2OS cells. Notably, the combination of MAPK/ERK kinase (MEK) and PI3K inhibition synergistically decreased viability in U2OS and AXT cells, but this effect was less pronounced in MG63 or Saos2 cells. Therefore, signal dependence for cell survival and crosstalk between MEK-ERK and PI3K-AKT pathways in osteosarcoma are cell context-dependent. The activation status of other kinases including CREB varied in a cell context-dependent manner, which might determine the response to MEK inhibition. A single dose of trametinib was sufficient to decrease the size of the primary tumor and circulating tumor cells in vivo. Moreover, combined administration of trametinib and rapamycin or conventional anticancer drugs further increased antitumor activity. Thus, given optimal biomarkers for predicting its effects, trametinib holds therapeutic potential for the treatment of osteosarcoma.

Advances in targeted therapy for osteosarcoma based on molecular classification

Osteosarcoma, a highly malignant tumor, is characterized by widespread and recurrent chromosomal and genetic abnormalities. In recent years, a number of elaborated sequencing analyses have made it possible to cluster the osteosarcoma based on the identification of candidate driver genes and develop targeted therapy. Here, we reviewed recent next-generation genome sequencing studies and advances in targeted therapies for osteosarcoma based on molecular classification. First, we stratified osteosarcomas into ten molecular subtypes based on genetic changes. And we analyzed potential targeted therapies for osteosarcoma based on the identified molecular subtypes. Finally, the development of targeted therapies for osteosarcoma investigated in clinical trials were further summarized and discussed. Therefore, we indicated the importance of molecular classification on the targeted therapy for osteosarcoma. And the stratification of patients based on the genetic characteristics of osteosarcoma will help to obtain a better therapeutic response to targeted therapies, bringing us closer to the era of personalized medicine.

Signaling pathways in Rhabdomyosarcoma invasion and metastasis

Rhabdomyosarcoma (RMS) is an aggressive childhood mesenchymal tumor with two major molecular and histopathologic subtypes: fusion-positive (FP)RMS, characterized by the PAX3-FOXO1 fusion protein and largely of alveolar histology, and fusion-negative (FN)RMS, the majority of which exhibit embryonal tumor histology. Metastatic disease continues to be associated with poor overall survival despite intensive treatment strategies. Studies on RMS biology have provided some insight into autocrine as well as paracrine signaling pathways that contribute to invasion and metastatic propensity. Such pathways include those driven by the PAX3-FOXO1 fusion oncoprotein in FPRMS and signaling pathways such as IGF/RAS/MEK/ERK, PI3K/AKT/mTOR, cMET, FGFR4, and PDGFR in both FP and FNRMS. In addition, specific cytoskeletal proteins, G protein coupled receptors, Hedgehog, Notch, Wnt, Hippo, and p53 pathways play a role, as do specific microRNA. Paracrine factors, including secreted proteins and RMS-derived exosomes that carry cargo of protein and miRNA, have also recently emerged as potentially important players in RMS biology. This review summarizes the known factors contributing to RMS invasion and metastasis and their implications on identifying targets for treatment and a better understanding of metastatic RMS.

Buparlisib modulates PD-L1 expression in head and neck squamous cell carcinoma cell lines

High expression of the immune checkpoint receptor PD-L1 is associated with worse patient outcome in a variety of human cancers, including head and neck squamous cell carcinoma (HNSCC). Binding of PD-L1 with its partner PD-1 generates an inhibitory signal that dampens the immune system. Immunotherapy, that is blocking the PD-1/PD-L1 checkpoint, has proven to be an effective tool in cancer therapy. However, not all patients are able to benefit from this immune checkpoint inhibition. Therefore, evidence is growing of intrinsic PD-L1 signaling in cancer cells. For example, intrinsic PD-L1 expression was associated with PI3K/Akt/mTOR signaling, which is part of diverse oncogenic processes including cell proliferation, growth and survival. In this study we demonstrate the effects of PI3K/Akt/mTOR pathway inhibition by buparlisib on PD-L1 expression in HNSCC cell lines. After buparlisib treatment for 72 h, PD-L1 was downregulated in total cell lysates of HNSCC cells. Moreover, flow cytometry revealed a downregulation of PD-L1 membrane expression. Interestingly, the buparlisib mediated effects on PD-L1 expression were reduced by additional irradiation. In PD-L1 overexpressing cells, the buparlisib induced inhibition of proliferation was neutralized. In summary, our findings imply that blocking the PI3K/Akt/mTOR pathway could be a good additional therapy for patients who show poor response to immune checkpoint therapy.

Characterization of mTOR Activity and Metabolic Profile in Pediatric Rhabdomyosarcoma

mTOR activation has been observed in rhabdomyosarcoma (RMS); however, mTOR complex (mTORC) 1 inhibition has had limited success thus far. mTOR activation alters the metabolic pathways, which is linked to survival and metastasis. These pathways have not been thoroughly analyzed in RMSs. We performed immunohistochemistry on 65 samples to analyze the expression of mTOR complexes (pmTOR, pS6, Rictor), and several metabolic enzymes (phosphofructokinase, lactate dehydrogenase-A, β-F1-ATPase, glucose-6-phosphate dehydrogenase, glutaminase). RICTOR amplification, as a potential mechanism of Rictor overexpression, was analyzed by FISH and digital droplet PCR. In total, 64% of the studied primary samples showed mTOR activity with an mTORC2 dominance (82%). Chemotherapy did not cause any relevant change in mTOR activity. Elevated mTOR activity was associated with a worse prognosis in relapsed cases. RICTOR amplification was not confirmed in any of the cases. Our findings suggest the importance of the Warburg effect and the pentose-phosphate pathway beside a glutamine demand in RMS cells. The expression pattern of the studied mTOR markers can explain the inefficacy of mTORC1 inhibitor therapy. Therefore, we suggest performing a detailed investigation of the mTOR profile before administering mTORC1 inhibitor therapy. Furthermore, our findings highlight that targeting the metabolic plasticity could be an alternative therapeutic approach.

MicroRNA-mRNA networks define translatable molecular outcome phenotypes in osteosarcoma

There is a lack of well validated prognostic biomarkers in osteosarcoma, a rare, recalcitrant disease for which treatment standards have not changed in over 20 years. We performed microRNA sequencing in 74 frozen osteosarcoma biopsy samples, constituting the largest single center translationally analyzed osteosarcoma cohort to date, and we separately analyzed a multi-omic dataset from a large NCI supported national cooperative group cohort. We validated the prognostic value of candidate microRNA signatures and contextualized them in relevant transcriptomic and epigenomic networks. Our results reveal the existence of molecularly defined phenotypes associated with outcome independent of clinicopathologic features. Through machine learning based integrative pharmacogenomic analysis, the microRNA biomarkers identify novel therapeutics for stratified application in osteosarcoma. The previously unrecognized osteosarcoma subtypes with distinct clinical courses and response to therapy could be translatable for discerning patients appropriate for more intensified, less intensified, or alternate therapeutic regimens.

Macrophage-derived exosome-mimetic hybrid vesicles for tumor targeted drug delivery

Extracellular vesicles (EVs) are phospholipid and protein constructs which are continuously secreted by cells in the form of smaller (30-200 nm) and larger (micron size) particles. While all of these vesicles are called as EVs, the smaller size are normally called as exosomes. Small EVs (sEVs) have now been explored as a potential candidate in therapeutics delivery owing to their endogenous functionality, intrinsic targeting property, and ability to cooperate with a host defense mechanism. Considering these potentials, we hypothesize that immune cell-derived sEVs can mimic immune cell to target cancer. However, different sEVs isolation technique reported poor yield and loss of functional properties. To solve this problem, herein we hybridized sEVs with synthetic liposome to engineer vesicles with size less than 200 nm to mimic the size of exosome and named as hybrid exosome (HE). To achieve this goal, sEVs from mouse macrophage was hybridized with synthetic liposome to engineer HE. The fluorescence-based experiment confirmed the successful hybridization process yielding HE with the size of 177 ± 21 nm. Major protein analysis from Blot techniques reveal the presence of EV marker proteins CD81, CD63, and CD9. Differential cellular interaction of HE was observed when treated with normal and cancerous cells thereby supporting our hypothesis. Moreover, a water-soluble doxorubicin was loaded in HE. Drug-loaded HE showed enhanced toxicity against cancer cells and pH-sensitive drug release in acidic condition, benefiting drug delivery to acidic cancer environment. These results suggest that the engineered HE would be an exciting platform for tumor-targeted drug delivery. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EVs) are phospholipid and protein constructs which are continuously secreted by cells in the human body. These vesicles can efficiently deliver their parental biomolecules to the recipient cells and assist in intracellular communication without a direct cell-to-cell contact. Moreover, they have the ability to perform some of the molecular task similar to that of its parent cells. For example, exosome derived from immune cells can seek for diseased and/or inflammatory cells by reading the cell surface proteins. However, different EVs isolation techniques reported poor yield and loss of functional properties. Therefore, to overcome this limitation, we herein propose to re-engineer immuno-exosome with a synthetic liposome as a refined biomimetic nanostructure for the delivery of doxorubicin (clinical drug) for breast cancer treatment.

Targeted Therapy-based Combination Treatment in Rhabdomyosarcoma

Targeted therapies have revolutionized cancer treatment; however, progress lags behind in alveolar (ARMS) and embryonal rhabdomyosarcoma (ERMS), a soft-tissue sarcoma mainly occurring at pediatric and young adult age. Insulin-like growth factor 1 receptor (IGF1R)-directed targeted therapy is one of the few single-agent treatments with clinical activity in these diseases. However, clinical effects only occur in a small subset of patients and are often of short duration due to treatment resistance. Rational selection of combination treatments of either multiple targeted therapies or targeted therapies with chemotherapy could hypothetically circumvent treatment resistance mechanisms and enhance clinical efficacy. Simultaneous targeting of distinct mechanisms might be of particular interest in this regard, as this affects multiple hallmarks of cancer at once. To determine the most promising and clinically relevant targeted therapy-based combination treatments for ARMS and ERMS, we provide an extensive overview of preclinical and (early) clinical data concerning a variety of targeted therapy-based combination treatments. We concentrated on the most common classes of targeted therapies investigated in rhabdomyosarcoma to date, including those directed against receptor tyrosine kinases and associated downstream signaling pathways, the Hedgehog signaling pathway, apoptosis pathway, DNA damage response, cell-cycle regulators, oncogenic fusion proteins, and epigenetic modifiers. Mol Cancer Ther; 17(7); 1365-80. ©2018 AACR.

Antitumor effects of β-elemene via targeting the phosphorylation of insulin receptor

Ewing sarcoma family tumors (ESFTs) are a group of aggressive and highly metastatic tumors lacking efficient therapies. Insulin-like growth factor 1 receptor (IGF1R) blockade is one of the most efficient targeting therapy for ESFTs. However, the appliance is obstructed by drug resistance and disease recurrence due to the activation of insulin receptor (IR) signaling induced by IGF1R blockade. Herein β-elemene, a compound derived from natural plants, exhibited a remarkable proliferation repression on ESFT cells, which was weakened by a caspase inhibitor Z-VAD. β-elemene in combination with IGF1R inhibitors enhanced markedly the repression on cellular proliferation and mTOR activation by IGF1R inhibitors and suppressed the PI3K phosphorylation induced by IGF1R inhibitors. To investigate the mechanisms, we focused on the effects of β-elemene on IR signaling pathway. β-elemene significantly suppressed the insulin-driven cell growth and the activation of mTOR and PI3K in tumor cells, while the toxicity to normal hepatocytes was much lower. Further, the phosphorylation of IR was found to be suppressed notably by β-elemene specifically in tumor cells other than normal hepatocytes. In addition, β-elemene inhibited the growth of ESFT xenografts in vivo, and the phosphorylation of IR and S6 ribosomal protein was significantly repressed in the β-elemene-treated xenografts. These data suggest that β-elemene targets IR phosphorylation to inhibit the proliferation of tumor cells specifically and enhance the effects of IGF1R inhibitors. Thus, this study provides evidence for novel approaches by β-elemene alone or in combination with IGF1R blockades in ESFTs and IR signaling hyperactivated tumors.

Inhibitory effect of NVP-BKM120 on cholangiocarcinoma cell growth

Abnormal activation of the phosphatidylinositol 3-kinase (PI3K) pathway has been demonstrated in certain types of cancer, including cholangiocarcinoma (CCA). This pathway may therefore be a promising target for CCA treatment. The present study assessed the inhibitory effect of NVP-BKM120, a pan-class I PI3K inhibitor, on CCA cell growth. This inhibitory effect was determined using CCA cell lines and in CCA-inoculated mice. The result from sulforhodamine B (SRB) assay demonstrated that NVP-BKM120 treatment inhibited CCA cell growth in a dose-dependent manner, even at the lowest tested concentration. The in vivo study revealed that oral administration of NVP-BKM120 (10 or 30 mg/kg) to CCA-inoculated nude mice led to a reduction in tumor growth when compared with controls, which was indicated by an immunohistochemical assay for Ki67 expression. In addition, the result from TUNEL assay demonstrated that NVP-BKM120 induced cancer cell death without any signs of toxicity, which indicated by the body weight of mice (data not shown). Western blot analysis demonstrated that NVP-BKM120 inhibited CCA cell growth by suppressing RAC serine/threonine protein kinase/mechanistic target of rapamycin activation and inhibiting the phosphorylation of phosphatase and tensin homolog, which is the inactivation form of the negative regulator of this pathway. Therefore, the results of the present study indicated that NVP-BKM120 should be considered as a therapeutic agent against CCA that could be used to improve treatment.

Advances in sarcoma gene mutations and therapeutic targets

Sarcomas are rare and complex malignancies that have been associated with a poor prognostic outcome. Over the last few decades, traditional treatment with surgery and/or chemotherapy has not significantly improved outcomes for most types of sarcomas. In recent years, there have been significant advances in the understanding of specific gene mutations that are important in driving the pathogenesis and progression of sarcomas. Identification of these new gene mutations, using next-generation sequencing and advanced molecular techniques, has revealed a range of potential therapeutic targets. This, in turn, may lead to the development of novel agents targeted to different sarcoma subtypes. In this review, we highlight the advances made in identifying sarcoma gene mutations, including those of p53, RB, PI3K and IDH genes, as well as novel therapeutic strategies aimed at utilizing these mutant genes. In addition, we discuss a number of preclinical studies and ongoing early clinical trials in sarcoma targeting therapies, as well as gene editing technology, which may provide a better choice for sarcoma patient management.

BKM120 induces apoptosis and inhibits tumor growth in medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children, accounting for nearly 20 percent of all childhood brain tumors. New treatment strategies are needed to improve patient survival outcomes and to reduce adverse effects of current therapy. The phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) intracellular signaling pathway plays a key role in cellular metabolism, proliferation, survival and angiogenesis, and is often constitutively activated in human cancers, providing unique opportunities for anticancer therapeutic intervention. The aim of this study was to evaluate the pre-clinical activity of BKM120, a selective pan-class I PI3K inhibitor, on MB cell lines and primary samples. IC50 values of BKM120 in the twelve MB cell lines tested ranged from 0.279 to 4.38 μM as determined by cell viability assay. IncuCyte ZOOM Live-Cell Imaging system was used for kinetic monitoring of cytotoxicity of BKM120 and apoptosis in MB cells. BKM120 exhibited cytotoxicity in MB cells in a dose and time-dependent manner by inhibiting activation of downstream signaling molecules AKT and mTOR, and activating caspase-mediated apoptotic pathways. Furthermore, BKM120 decreased cellular glycolytic metabolic activity in MB cell lines in a dose-dependent manner demonstrated by ATP level per cell. In MB xenograft mouse study, DAOY cells were implanted in the flank of nude mice and treated with vehicle, BKM120 at 30 mg/kg and 60 mg/kg via oral gavage daily. BKM120 significantly suppressed tumor growth and prolonged mouse survival. These findings help to establish a basis for clinical trials of BKM120, which could be a novel therapy for the treatment of medulloblastoma patients.

High-Throughput Phenotypic Screening of Kinase Inhibitors to Identify Drug Targets for Polycystic Kidney Disease

Polycystic kidney disease (PKD) is a prevalent disorder characterized by renal cysts that lead to kidney failure. Various signaling pathways have been targeted to stop disease progression, but most interventions still focus on alleviating PKD-associated symptoms. The mechanistic complexity of the disease, as well as the lack of functional in vitro assays for compound testing, has made drug discovery for PKD challenging. To identify modulators of PKD, Pkd1^–/– kidney tubule epithelial cells were applied to a scalable and automated 3D cyst culture model for compound screening, followed by phenotypic profiling to determine compound efficacy. We used this screening platform to screen a library of 273 kinase inhibitors to probe various signaling pathways involved in cyst growth. We show that inhibition of several targets, including aurora kinase, CDK, Chk, IGF-1R, Syk, and mTOR, but, surprisingly, not PI3K, prevented forskolin-induced cyst swelling. Additionally, we show that multiparametric phenotypic classification discriminated potentially undesirable (i.e., cytotoxic) compounds from molecules inducing the desired phenotypic change, greatly facilitating hit selection and validation. Our findings show that a pathophysiologically relevant 3D cyst culture model of PKD coupled to phenotypic profiling can be used to identify potentially therapeutic compounds and predict and validate molecular targets for PKD.

OSBPL10, RXRA and lipid metabolism confer African-ancestry protection against dengue haemorrhagic fever in admixed Cubans

Ethnic groups can display differential genetic susceptibility to infectious diseases. The arthropod-born viral dengue disease is one such disease, with empirical and limited genetic evidence showing that African ancestry may be protective against the haemorrhagic phenotype. Global ancestry analysis based on high-throughput genotyping in admixed populations can be used to test this hypothesis, while admixture mapping can map candidate protective genes. A Cuban dengue fever cohort was genotyped using a 2.5 million SNP chip. Global ancestry was ascertained through ADMIXTURE and used in a fine-matched corrected association study, while local ancestry was inferred by the RFMix algorithm. The expression of candidate genes was evaluated by RT-PCR in a Cuban dengue patient cohort and gene set enrichment analysis was performed in a Thai dengue transcriptome. OSBPL10 and RXRA candidate genes were identified, with most significant SNPs placed in inferred weak enhancers, promoters and lncRNAs. OSBPL10 had significantly lower expression in Africans than Europeans, while for RXRA several SNPs may differentially regulate its transcription between Africans and Europeans. Their expression was confirmed to change through dengue disease progression in Cuban patients and to vary with disease severity in a Thai transcriptome dataset. These genes interact in the LXR/RXR activation pathway that integrates lipid metabolism and immune functions, being a key player in dengue virus entrance into cells, its replication therein and in cytokine production. Knockdown of OSBPL10 expression in THP-1 cells by two shRNAs followed by DENV2 infection tests led to a significant reduction in DENV replication, being a direct functional proof that the lower OSBPL10 expression profile in Africans protects this ancestry against dengue disease.

Dengue is a concern of worldwide health authorities given the increase on virus and vector dispersions. So far only one traditional GWAS survey has been performed in Vietnamese children. This disease is also epidemic in tropical and subtropical regions of the Americas, where most populations descend from a dynamic admixture between African, European and Native American backgrounds. Empirical evidence claimed that African descent was protective against dengue haemorrhagic phenotype in the Cuban population, and this study is the first to apply admixture mapping to identify candidate genes that confer African protection. We also present evidence that two candidate genes, OSBPL10 and RXRA, are differentially expressed along dengue disease progression in Cuban patients and in a Thai dengue transcriptome dataset, and directly show that knockdown of OSBPL10 gene expression leads to a significant reduction in DENV2 replication. A very important overall result of our work is that it provides a unifying framework for many genes that have been said to be protective in dengue. Our evidence places the LXR/RXR activation pathway at the center of natural dengue protection, and supports pursuing therapeutic techniques involving synthetic ligands of nuclear receptor genes or kinases inhibitors that interact with proteins involved in lipid metabolism.

Novel insights and therapeutic interventions for pediatric osteosarcoma

High-grade osteosarcomas are the most common primary malignant tumors of bone. With complete surgical resection and multi-agent chemotherapy up to 70% of patients with high-grade osteosarcomas and localized extremity tumors can become long-term survivors. The prognosis, however, is poor for patients with nonresectable, primary metastatic or relapsed disease. Outcome is essentially unchanged for three decades. Herein, we describe selected novel insights into the genomics, biology and immunology of the disease and discuss selected strategies, which hold promise to overcome the current stagnation in the therapeutic success in childhood osteosarcoma.

Future directions in the treatment of osteosarcoma

PURPOSE OF REVIEW

Overall survival rates for osteosarcoma have remained essentially unchanged over the past 3 decades despite attempts to improve outcome via dose intensification and modification based on response. This review describes recent findings from contemporary clinical trials, advances in the comprehension of osteosarcoma biology and genomic complexity, and potential opportunities using targeted and immune-mediated therapies.

RECENT FINDINGS

Recent results from international collaborative trials have failed to demonstrate an ability to improve outcomes using a design in which the randomized question is dictated based on histologic response to preoperative chemotherapy. Novel prognostic markers assessable at diagnosis are vital to identifying subsets of osteosarcoma. Clinical trials focus has now shifted to serial phase II studies of novel agents to evaluate for activity in recurrent and refractory disease. In-depth analyses have revealed profound genomic instability and heterogeneity across patients, with nearly universal TP53 aberration. Although driver mutational events have not clearly been established, frequent derangements in specific pathways may suggest opportunities for therapeutic exploitation. Genomic complexity may lend support to a role for immune-mediated therapies.

SUMMARY

Rigorous preclinical investigations are potentially generating novel strategies for the treatment of osteosarcoma that will inform the next generation of clinical trials, with the opportunity to identify agents that will improve survival outcomes.