Hedgehog pathway mutations drive oncogenic transformation in high-risk T-cell acute lymphoblastic leukemia

Curcumin and Methotrexate: A Promising Combination for Osteosarcoma Treatment via Hedgehog Pathway Inhibition

Osteosarcoma (OS) is the most severe bone tumor in children. A chemotherapy regimen includes a combination of high-dose Methotrexate (MTX), doxorubicin, and cisplatin. These drugs cause acute and chronic side effects, such as infections, thrombocytopenia, neutropenia, DNA damage, and inflammation. Therefore, to identify new therapeutic strategies, effective and with a safety profile, is necessary. The Hedgehog (Hh) signaling pathway involved in tumorigenesis is active in OS. Hh components Patched receptor 1 (PTCH1), Smoothened (SMO), and glioma-associated oncogene homolog transcription factors (GLI1 and GLI2) are overexpressed in OS cell lines and patient samples. Curcumin (CUR)-with antioxidant and anti-cancer properties-downregulates Hh components in cancer, inhibiting progression. This study investigates CUR effects on the MG-63 OS cell line, alone and combined with MTX, to propose a novel therapeutic approach. Our study suggests CUR as a novel therapeutic agent in OS, particularly when combined with MTX. Targeting the Hh signaling pathway, CUR and MTX showed significant pro-apoptotic effects, increasing the BAX/Bcl-2 ratio and total apoptotic cell percentage. They reduced the expression of Hh pathway components (PTCH1, SMO, GLI1, and GLI2), inhibiting OS cell proliferation, survival, and invasion. CUR and MTX combined determined a β-Catenin decrease and a trend toward reducing NF-kB and matrix metalloproteinases (MMP-2 and MMP-9). Our findings suggest CUR as a support to OS treatment, improving outcomes and reducing the adverse effects of current therapies.

A simple and scalable zebrafish model of Sonic hedgehog medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children and is stratified into three major subgroups. The Sonic hedgehog (SHH) subgroup represents ∼30% of all MB cases and has significant survival disparity depending upon TP53 status. Here, we describe a zebrafish model of SHH MB using CRISPR to create mutant ptch1, the primary genetic driver of human SHH MB. In these animals, tumors rapidly arise in the cerebellum and resemble human SHH MB by histology and comparative onco-genomics. Similar to human patients, MB tumors with loss of both ptch1 and tp53 have aggressive tumor histology and significantly worse survival outcomes. The simplicity and scalability of the ptch1-crispant MB model makes it highly amenable to CRISPR-based genome-editing screens to identify genes required for SHH MB tumor formation in vivo, and here we identify the gene encoding Grk3 kinase as one such target.

Galloyl-oligochitosan nano-vehicles for effective and controlled propolis delivery targeting upgrading its antioxidant and antiproliferative potential

A new conjugate, galloyl-oligochitosan nanoparticles (GOCNPs), was fabricated and used as nano-vehicle for effective and controlled delivery of propolis extract (PE) in the form of PE#GOCNPs, targeting improving its pharmaceutical potential. H-bonding interactions between the carboxyl, amino, and hydroxyl groups of the GOCNPs and PE resulted in successful encapsulation, with an entrapment efficacy of 97.3 %. The PE#GOCNPs formulation also exhibited excellent physicochemical stability and time-triggered drug release characteristics under physiological conditions. Furthermore, PE#GOCNPs showed significant activity against MCF-7 and HEPG2 carcinoma cells by scavenging free oxygen radicals and upregulating antioxidant enzymes. Additionally, PE#GOCNPs displayed anti-inflammatory properties by increasing IL10 and reducing pro-inflammatory cytokines more effectively than celecoxib. Furthermore, PE#GOCNPs reduced the expression of epidermal growth factor receptor (EGFR) and survivin genes. Furthermore, the encapsulated PE demonstrated significant activity in suppressing sonic hedgehog protein (SHH). The use of GOCNPs in combination with propolis presents a promising new strategy for chemotherapy with reduced toxicity and enhanced biocompatibility. This novel approach has the potential to revolutionize the field of chemotherapy. Future studies should focus on the application of the encapsulated PE in various cancer cell lines, distinct gene expression factors, and cell cycles.

Zebrafish-A Suitable Model for Rapid Translation of Effective Therapies for Pediatric Cancers

Pediatric cancers are the leading cause of disease-related deaths in children and adolescents. Most of these tumors are difficult to treat and have poor overall survival. Concerns have also been raised about drug toxicity and long-term detrimental side effects of therapies. In this review, we discuss the advantages and unique attributes of zebrafish as pediatric cancer models and their importance in targeted drug discovery and toxicity assays. We have also placed a special focus on zebrafish models of pediatric brain cancers-the most common and difficult solid tumor to treat.

A Simple and Scalable Zebrafish Model of Sonic Hedgehog Medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in children and is stratified into three major subgroups. The Sonic hedgehog (SHH) subgroup represents ~30% of all MB cases and has significant survival disparity depending upon TP53 status. Here, we describe the first zebrafish model of SHH MB using CRISPR to mutate ptch1, the primary genetic driver in human SHH MB. These tumors rapidly arise adjacent to the valvula cerebelli and resemble human SHH MB by histology and comparative genomics. In addition, ptch1-deficient MB tumors with loss of tp53 have aggressive tumor histology and significantly worse survival outcomes, comparable to human patients. The simplicity and scalability of the ptch1 MB model makes it highly amenable to CRISPR-based genome editing screens to identify genes required for SHH MB tumor formation in vivo, and here we identify the grk3 kinase as one such target.

Targeting cancer hallmark vulnerabilities in hematologic malignancies by interfering with Hedgehog/GLI signaling

Understanding the genetic alterations, disrupted signaling pathways, and hijacked mechanisms in oncogene-transformed hematologic cells is critical for the development of effective and durable treatment strategies against liquid tumors. In this review, we focus on the specific involvement of the Hedgehog (HH)/GLI pathway in the manifestation and initiation of various cancer features in hematologic malignancies, including multiple myeloma, T- and B-cell lymphomas, and lymphoid and myeloid leukemias. By reviewing canonical and noncanonical, Smoothened-independent HH/GLI signaling and summarizing preclinical in vitro and in vivo studies in hematologic malignancies, we elucidate common molecular mechanisms by which HH/GLI signaling controls key oncogenic processes and cancer hallmarks such as cell proliferation, cancer stem cell fate, genomic instability, microenvironment remodeling, and cell survival. We also summarize current clinical trials with HH inhibitors and discuss successes and challenges, as well as opportunities for future combined therapeutic approaches. By providing a bird's eye view of the role of HH/GLI signaling in liquid tumors, we suggest that a comprehensive understanding of the general oncogenic effects of HH/GLI signaling on the formation of cancer hallmarks is essential to identify critical vulnerabilities within tumor cells and their supporting remodeled microenvironment, paving the way for the development of novel and efficient personalized combination therapies for hematologic malignancies.

Association of CDKN2A/B mutations, PD-1, and PD-L1 with the risk of acute lymphoblastic leukemia in children

PURPOSE

Currently, the significance of CDKN2A/B mutations in the pathogenesis and prognosis of acute lymphoblastic leukemia (ALL) is inconclusive. In this study, we analyzed the genetic and clinical features of children with CDKN2A/B mutations in ALL. In addition, we evaluated the expression and significance of programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-L1) in serum and explored their role in the susceptibility of childhood ALL.

METHODS

We sequenced CDKN2A/B in the peripheral blood of 120 children with ALL and 100 healthy children with physical examination. The levels of CD4+ T, CD8+ T, and NK cells were measured by flow cytometry (FCM). Furthermore, the expression of PD-1 and PD-L1 was detected by ELISA.

RESULTS

We found 32 cases of CDKN2A rs3088440 and 11 of CDKN2B rs2069426 in 120 ALL children. Children with ALL in the CDKN2A rs3088440 were more likely to have hepatosplenomegaly (P = 0.019) and high risk (P = 0.014) than the wild group. In contrast, CDKN2B rs2069426 was more likely to develop lymph node metastasis (P = 0.017). The level of PD-L1 in the serum of ALL children was significantly higher than that of the control group, and there was no significant difference in PD-1 (P < 0.001). Additionally, children with CDKN2A rs3088440 had reduced CD8+ T cell counts than the wild group (P = 0.039).

CONCLUSION

CDKN2A rs3088440 and CDKN2B rs2069426 may be related to the occurrence and development of ALL in Chinese children. Additionally, PD-1/PD-L1 may be involved in the immune escape process of ALL, which is expected to become a new target for the treatment of the disease.

The Role of Hedgehog Signaling Pathway in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth leading malignancy worldwide, with a poor prognosis and limited treatment options. Molecularly targeted therapies for HNSCC are still lacking. However, recent reports provide novel insights about many molecular alterations in HNSCC that may be useful in future therapies. Therefore, it is necessary to identify new biomarkers that may provide a better prediction of the disease and promising targets for personalized therapy. The poor response of HNSCC to therapy is attributed to a small population of tumor cells called cancer stem cells (CSCs). Growing evidence indicates that the Hedgehog (HH) signaling pathway plays a crucial role in the development and maintenance of head and neck tissues. The HH pathway is normally involved in embryogenesis, stem cell renewal, and tissue regeneration. However, abnormal activation of the HH pathway is also associated with carcinogenesis and CSC regulation. Overactivation of the HH pathway was observed in several tumors, including basal cell carcinoma, that are successfully treated with HH inhibitors. However, clinical studies about HH pathways in HNSCC are still rare. In this review, we summarize the current knowledge and recent advances regarding the HH pathway in HNSCC and discuss its possible implications for prognosis and future therapy.

Beyond Corticoresistance, A Paradoxical Corticosensitivity Induced by Corticosteroid Therapy in Pediatric Acute Lymphoblastic Leukemias

Known as a key effector in relapse of acute lymphoblastic leukemia (ALL), resistance to drug-induced apoptosis, is tightly considered one of the main prognostic factors for the disease. ALL cells are constantly developing cellular strategies to survive and resist therapeutic drugs. Glucocorticoids (GCs) are one of the most important agents used in the treatment of ALL due to their ability to induce cell death. The mechanisms of GC resistance of ALL cells are largely unknown and intense research is currently focused on this topic. Such resistance can involve different cellular and molecular mechanisms, including the modulation of signaling pathways involved in the regulation of proliferation, apoptosis, autophagy, metabolism, epigenetic modifications and tumor suppressors. Recently, several studies point to the paradoxical role of GCs in many survival processes that may lead to therapy-induced resistance in ALL cells, which we called "paradoxical corticosensitivity". In this review, we aim to summarize all findings on cell survival pathways paradoxically activated by GCs with an emphasis on previous and current knowledge on gene expression and signaling pathways.

Understanding the Roles of the Hedgehog Signaling Pathway during T-Cell Lymphopoiesis and in T-Cell Acute Lymphoblastic Leukemia (T-ALL)

The Hedgehog (HH) signaling network is one of the main regulators of invertebrate and vertebrate embryonic development. Along with other networks, such as NOTCH and WNT, HH signaling specifies both the early patterning and the polarity events as well as the subsequent organ formation via the temporal and spatial regulation of cell proliferation and differentiation. However, aberrant activation of HH signaling has been identified in a broad range of malignant disorders, where it positively influences proliferation, survival, and therapeutic resistance of neoplastic cells. Inhibitors targeting the HH pathway have been tested in preclinical cancer models. The HH pathway is also overactive in other blood malignancies, including T-cell acute lymphoblastic leukemia (T-ALL). This review is intended to summarize our knowledge of the biological roles and pathophysiology of the HH pathway during normal T-cell lymphopoiesis and in T-ALL. In addition, we will discuss potential therapeutic strategies that might expand the clinical usefulness of drugs targeting the HH pathway in T-ALL.

Modeling leukemia with zebrafish (Danio rerio): Towards precision medicine

Leukemia is a type of blood cancer characterized by high genetic heterogeneity and fatality. While chemotherapy remains the primary form of treatment for leukemia, its effectiveness was profoundly diminished by the genetic heterogeneity and cytogenetic abnormalities of leukemic cells. Therefore, there is an unmet need to develop precision medicine for leukemia with distinct genetic backgrounds. Zebrafish (Danio rerio), a freshwater fish with exceptional feasibility in genome editing, is a powerful tool for rapid human cancer modeling. In the past decades, zebrafish have been adopted in modeling human leukemia, exploring the molecular mechanisms of underlying genetic abnormalities, and discovering novel therapeutic agents. Although many recurrent mutations of leukemia have been modeled in zebrafish for pathological study and drug discovery, its great potential in leukemia modeling was not yet fully exploited, particularly in precision medicine. In this review, we evaluated the current zebrafish models of leukemia/pre-leukemia and genetic techniques and discussed the potential of zebrafish models with novel techniques, which may contribute to the development of zebrafish as a disease model for precision medicine in treating leukemia.

The role of Hedgehog and Notch signaling pathway in cancer

Notch and Hedgehog signaling are involved in cancer biology and pathology, including the maintenance of tumor cell proliferation, cancer stem-like cells, and the tumor microenvironment. Given the complexity of Notch signaling in tumors, its role as both a tumor promoter and suppressor, and the crosstalk between pathways, the goal of developing clinically safe, effective, tumor-specific Notch-targeted drugs has remained intractable. Drugs developed against the Hedgehog signaling pathway have affirmed definitive therapeutic effects in basal cell carcinoma; however, in some contexts, the challenges of tumor resistance and recurrence leap to the forefront. The efficacy is very limited for other tumor types. In recent years, we have witnessed an exponential increase in the investigation and recognition of the critical roles of the Notch and Hedgehog signaling pathways in cancers, and the crosstalk between these pathways has vast space and value to explore. A series of clinical trials targeting signaling have been launched continually. In this review, we introduce current advances in the understanding of Notch and Hedgehog signaling and the crosstalk between pathways in specific tumor cell populations and microenvironments. Moreover, we also discuss the potential of targeting Notch and Hedgehog for cancer therapy, intending to promote the leap from bench to bedside.

Specific lncRNA signatures discriminate childhood acute leukaemias: a pilot study

BACKGROUND

Long non-coding RNAs are RNAs longer than 200 bps that do not encode any proteins and are able to alter gene expression by acting on different steps of regulation, including DNA methylation and chromatin structure. They represent a class of biomarkers of crescent interest in the hematologic and oncologic fields. Recent studies showed that the expression levels of specific lncRNAs correlate with the prognosis of paediatric patients with Acute Lymphoblastic Leukaemia.

METHODS

We used NGS approaches to analyse the transcriptome of 9 childhood B-ALL patients and 6 childhood T-ALL patients, in comparison with B and T healthy lymphocytes from cord blood. We validate our findings both ex vivo, in a different cohort of 10 B-ALL and 10 T-ALL patients, and in silico using public datasets.

RESULTS

We characterised the lncRNA landscape for B-ALL, T-ALL, healthy B, and T cell progenitors. From the characterised signature, we selected candidate lncRNAs able to discriminate not only B-ALL and T-ALL from healthy subjects but also between the two types of leukaemia, and subsequently validated their potential as a diagnostic tool in an additional cohort of paediatric patients. We confirmed our finding with open access transcriptomic data, comparing ALL lncRNAs with AML lncRNA landscape as well. Finally, expression correlation analyses of T-ALL selected lncRNA biomarkers suggested a possible role in lymphocyte activation and the β-catenin signalling pathway for AC247036.1 and involvement in hedgehog signalling for HHIP-AS1.

CONCLUSIONS

Our work identified a lncRNA signature discriminating paediatric B-ALL and T-ALL from healthy subjects, between them and from AML. This study provides the keystone to future clinical studies determining the theragnostic value of the characterised long non coding transcriptome panorama in a clinical setting for childhood patient management.

Ciliary signaling in stem cells in health and disease: Hedgehog pathway and beyond

The primary cilium is a hair-like sensory compartment that protrudes from the cellular surface. The primary cilium is enriched in a variety of signaling molecules that regulate cellular activities. Stem cells have primary cilia. They reside in a specialized environment, called the stem cell niche. This niche contains a variety of secreted factors, and some of their receptors are localized in the primary cilia of stem cells. Here, we summarize the current understanding of the function of cilia in compartmentalized signaling in stem cells. We describe how ciliary signaling regulates stem cells and progenitor cells during development, tissue homeostasis and tumorigenesis. We summarize our understanding of cilia regulated signaling -primary involving the hedgehog pathway- in stem cells in diverse settings that include neuroepithelial cells, radial glia, cerebellar granule neuron precursors, hematopoietic stem cells, hair follicle stem cells, bone marrow mesenchymal stem cells and mammary gland stem cells. Overall, our review highlights a variety of roles that ciliary signaling plays in regulating stem cells throughout life.

High Circulating Sonic Hedgehog Protein Is Associated With Poor Outcome in EGFR-Mutated Advanced NSCLC Treated With Tyrosine Kinase Inhibitors

Introduction

Growing preclinical evidence has suggested that the Sonic hedgehog (Shh) pathway is involved in resistance to tyrosine kinase inhibitor (TKI) therapy for EGFR-mutated (EGFRm) non-small cell lung cancer (NSCLC). However, little is known concerning the prognostic value of this pathway in this context.

Materials and Methods

We investigated the relationship between plasma levels of Shh and EGFRm NSCLC patients’ outcome with EGFR TKIs. We included 74 consecutive patients from two institutions with EGFRm advanced NSCLC treated by EGFR TKI as first-line therapy. Plasma samples were collected longitudinally for each patient and were analyzed for the expression of Shh using an ELISA assay. The activation of the Shh–Gli1 pathway was assessed through immunohistochemistry (IHC) of Gli1 and RT-qPCR analysis of the transcripts of Gli1 target genes in 14 available tumor biopsies collected at diagnosis (baseline).

Results

Among the 74 patients, only 61 had baseline (diagnosis) plasma samples, while only 49 patients had plasma samples at the first evaluation. Shh protein was detectable in all samples at diagnosis (n = 61, mean = 1,041.2 ± 252.5 pg/ml). Among the 14 available tumor biopsies, nuclear expression of Gli1 was observed in 57.1% (8/14) of patients’ biopsies. Shh was significantly (p < 0.05) enriched in youth (age < 68), male, nonsmokers, patients with a PS > 1, and patients presenting more than 2 metastatic sites and L858R mutation. Higher levels of Shh correlated with poor objective response to TKI, shorter progression-free survival (PFS), and T790M-independent mechanism of resistance. In addition, the rise of plasma Shh levels along the treatment was associated with the emergence of drug resistance in patients presenting an initial good therapy response.

Conclusion

These data support that higher levels of plasma Shh at diagnosis and increased levels of Shh along the course of the disease are related to the emergence of TKI resistance and poor outcome for EGFR-TKI therapy, suggesting that Shh levels could stand both as a prognostic and as a resistance biomarker for the management of EGFR-mutated NSCLC patients treated with EGFR-TKI.

A Synopsis of Signaling Crosstalk of Pericytes and Endothelial Cells in Salivary Gland

The salivary gland (SG) microvasculature constitutes a dynamic cellular organization instrumental to preserving tissue stability and homeostasis. The interplay between pericytes (PCs) and endothelial cells (ECs) culminates as a key ingredient that coordinates the development, maturation, and integrity of vessel building blocks. PCs, as a variety of mesenchymal stem cells, enthrall in the field of regenerative medicine, supporting the notion of regeneration and repair. PC-EC interconnections are pivotal in the kinetic and intricate process of angiogenesis during both embryological and post-natal development. The disruption of this complex interlinkage corresponds to SG pathogenesis, including inflammation, autoimmune disorders (Sjögren’s syndrome), and tumorigenesis. Here, we provided a global portrayal of major signaling pathways between PCs and ECs that cooperate to enhance vascular steadiness through the synergistic interchange. Additionally, we delineated how the crosstalk among molecular networks affiliate to contribute to a malignant context. Additionally, within SG microarchitecture, telocytes and myoepithelial cells assemble a labyrinthine companionship, which together with PCs appear to synchronize the regenerative potential of parenchymal constituents. By underscoring the intricacy of signaling cascades within cellular latticework, this review sketched a perceptive basis for target-selective drugs to safeguard SG function.

Hedgehog/GLI1 signaling pathway regulates the resistance to cisplatin in human osteosarcoma

Purpose: This study aimed to investigate the role and mechanism of Hedgehog/GLI1 signaling pathway in regulating the resistance to cisplatin in osteosarcoma (OS).

Materials and methods: Immunohistochemistry, western blotting and qRT-PCR assay were performed to analyze and compare the expression of GLI1 in OS tumor tissue and normal bone tissue as well as in cisplatin sensitive and resistant cell lines (SOSP-9607 and SOSP-9607/CR). Meanwhile, the biological role of GLI1 in OS was investigated by using down-regulated expression of GLI1 and functional assays, including CCK-8, colony formation assay, flow cytometry, and wound healing assay. Moreover, the relationship between GLI1 and γ-H2AX (DNA damage protein) in cells treated with GLI1 siRNA and cisplatin was examined using western blot analysis. In addition, GANT61, a inhibitor of Hedgehog pathway was used in xenograft tumor model to further verify the effect and mechanism of GLI1 on cisplatin resistance in OS.

Results: We showed that GLI1 expression was up-regulated in OS patients and cisplatin-resistant cells. Silencing GLI1 significantly restored the sensitivity of OS to cisplatin, reduced proliferation, migration and cloning capacity of cisplatin sensitive and resistant cells, and increased the apoptosis rate in vitro. Furthermore, combined administration of GANT61 and cisplatin markedly inhibitted tumor growth in the mouse model. Mechanitic studies found that γ-H2AX is involved in the cisplatin resistance, and blockade of Hedgehog/GLI1 pathway increased the expression of γ-H2AX.

Conclusion: Abnormal activation of Hedgehog-GLI1 pathway can regulate the expression of γ-H2AX, thus affecting DNA damage and repair functions, and promoting acquired cisplatin resistance of OS.

The Role of Smoothened-Dependent and -Independent Hedgehog Signaling Pathway in Tumorigenesis

The Hedgehog (Hh)-glioma-associated oncogene homolog (GLI) signaling pathway is highly conserved among mammals, with crucial roles in regulating embryonic development as well as in cancer initiation and progression. The GLI transcription factors (GLI1, GLI2, and GLI3) are effectors of the Hh pathway and are regulated via Smoothened (SMO)-dependent and SMO-independent mechanisms. The SMO-dependent route involves the common Hh-PTCH-SMO axis, and mutations or transcriptional and epigenetic dysregulation at these levels lead to the constitutive activation of GLI transcription factors. Conversely, the SMO-independent route involves the SMO bypass regulation of GLI transcription factors by external signaling pathways and their interacting proteins or by epigenetic and transcriptional regulation of GLI transcription factors expression. Both routes of GLI activation, when dysregulated, have been heavily implicated in tumorigenesis of many known cancers, making them important targets for cancer treatment. Hence, this review describes the various SMO-dependent and SMO-independent routes of GLI regulation in the tumorigenesis of multiple cancers in order to provide a holistic view of the paradigms of hedgehog signaling networks involving GLI regulation. An in-depth understanding of the complex interplay between GLI and various signaling elements could help inspire new therapeutic breakthroughs for the treatment of Hh-GLI-dependent cancers in the future. Lastly, we have presented an up-to-date summary of the latest findings concerning the use of Hh inhibitors in clinical developmental studies and discussed the challenges, perspectives, and possible directions regarding the use of SMO/GLI inhibitors in clinical settings.

Current and emerging therapeutic approaches for T-cell acute lymphoblastic leukaemia

T-cell ALL (T-ALL) is an aggressive malignancy of T-cell progenitors. Although survival outcomes in T-ALL have greatly improved over the past 50 years, relapsed and refractory cases remain extremely challenging to treat and those who cannot tolerate intensive treatment continue to have poor outcomes. Furthermore, T-ALL has proven a more challenging immunotherapeutic target than B-ALL. In this review we explore our expanding knowledge of the basic biology of T-ALL and how this is paving the way for repurposing established treatments and the development of novel therapeutic approaches.

Responsiveness to Hedgehog Pathway Inhibitors in T-Cell Acute Lymphoblastic Leukemia Cells Is Highly Dependent on 5'AMP-Activated Kinase Inactivation

Numerous studies have shown that hedgehog inhibitors (iHHs) only partially block the growth of tumor cells, especially in vivo. Leukemia often expands in a nutrient-depleted environment (bone marrow and thymus). In order to identify putative signaling pathways implicated in the adaptive response to metabolically adverse conditions, we executed quantitative phospho-proteomics in T-cell acute lymphoblastic leukemia (T-ALL) cells subjected to nutrient-depleted conditions (serum starvation). We found important modulations of peptides phosphorylated by critical signaling pathways including casein kinase, mammalian target of rapamycin, and 5′AMP-activated kinase (AMPK). Surprisingly, in T-ALL cells, AMPK signaling was the most consistently downregulated pathway under serum-depleted conditions, and this coincided with increased GLI1 expression and sensitivity to iHHs, especially the GLI1/2 inhibitor GANT-61. Increased sensitivity to GANT-61 was also found following genetic inactivation of the catalytic subunit of AMPK (AMPKα1) or pharmacological inhibition of AMPK by Compound C. Additionally, patient-derived xenografts showing high GLI1 expression lacked activated AMPK, suggesting an important role for this signaling pathway in regulating GLI1 protein levels. Further, joint targeting of HH and AMPK signaling pathways in T-ALL cells by GANT-61 and Compound C significantly increased the therapeutic response. Our results suggest that metabolic adaptation that occurs under nutrient starvation in T-ALL cells increases responsiveness to HH pathway inhibitors through an AMPK-dependent mechanism and that joint therapeutic targeting of AMPK signaling and HH signaling could represent a valid therapeutic strategy in rapidly expanding tumors where nutrient availability becomes limiting.

Comprehending the crosstalk between Notch, Wnt and Hedgehog signaling pathways in oral squamous cell carcinoma - clinical implications

BACKGROUND

Oral squamous cell carcinoma (OSCC) is a malignant oral cavity neoplasm that affects many people, especially in developing countries. Despite several advances that have been made in diagnosis and treatment, the morbidity and mortality rates due to OSCC remain high. Accumulating evidence indicates that aberrant activation of cellular signaling pathways, such as the Notch, Wnt and Hedgehog pathways, occurs during the development and metastasis of OSCC. In this review, we have articulated the roles of the Notch, Wnt and Hedgehog signaling pathways in OSCC and their crosstalk during tumor development and progression. We have also examined possible interactions and associations between these pathways and treatment regimens that could be employed to effectively tackle OSCC and/or prevent its recurrence.

CONCLUSIONS

Activation of the Notch signaling pathway upregulates the expression of several genes, including c-Myc, β-catenin, NF-κB and Shh. Associations between the Notch signaling pathway and other pathways have been shown to enhance OSCC tumor aggressiveness. Crosstalk between these pathways supports the maintenance of cancer stem cells (CSCs) and regulates OSCC cell motility. Thus, application of compounds that block these pathways may be a valid strategy to treat OSCC. Such compounds have already been employed in other types of cancer and could be repurposed for OSCC.

Medulloblastoma drugs in development: Current leads, trials and drawbacks

Medulloblastoma (MB) is the most common malignant brain tumor in children. Current treatment for MB includes surgical resection, radiotherapy and chemotherapy. Despite significant progress in its management, a portion of children relapse and tumor recurrence carries a poor prognosis. Based on their molecular and clinical characteristics, MB patients are clinically classified into four groups: Wnt, Hh, Group 3, and Group 4. With our increased understanding of relevant molecular pathways disrupted in MB, the development of targeted therapies for MB has also increased. Targeted drugs have shown unique privileges over traditional cytotoxic therapies in balancing efficacy and toxicity, with many of them approved and widely used clinically. The aim of this review is to present the recent progress on targeted chemotherapies for the treatment of all classes of MB.

Prostaglandin E2 stimulates cAMP signaling and resensitizes human leukemia cells to glucocorticoid-induced cell death

Glucocorticoid (GC) resistance remains a clinical challenge in pediatric acute lymphoblastic leukemia where response to GC is a reliable prognostic indicator. To identify GC resistance pathways, we conducted a genome-wide, survival-based, short hairpin RNA screen in murine T-cell acute lymphoblastic leukemia (T-ALL) cells. Genes identified in the screen interfere with cyclic adenosine monophosphate (cAMP) signaling and are underexpressed in GC-resistant or relapsed ALL patients. Silencing of the cAMP-activating Gnas gene interfered with GC-induced gene expression, resulting in dexamethasone resistance in vitro and in vivo. We demonstrate that cAMP signaling synergizes with dexamethasone to enhance cell death in GC-resistant human T-ALL cells. We find the E prostanoid receptor 4 expressed in T-ALL samples and demonstrate that prostaglandin E2 (PGE2) increases intracellular cAMP, potentiates GC-induced gene expression, and sensitizes human T-ALL samples to dexamethasone in vitro and in vivo. These findings identify PGE2 as a target for GC resensitization in relapsed pediatric T-ALL.

Identification of prognostic factors in childhood T-cell acute lymphoblastic leukemia: Results from DFCI ALL Consortium Protocols 05-001 and 11-001

BACKGROUND/OBJECTIVES

While outcomes for pediatric T-cell acute lymphoblastic leukemia (T-ALL) are favorable, there are few widely accepted prognostic factors, limiting the ability to risk stratify therapy.

DESIGN/METHODS

Dana-Farber Cancer Institute (DFCI) Protocols 05-001 and 11-001 enrolled pediatric patients with newly diagnosed B- or T-ALL from 2005 to 2011 and from 2012 to 2015, respectively. Protocol therapy was nearly identical for patients with T-ALL (N = 123), who were all initially assigned to the high-risk arm. End-induction minimal residual disease (MRD) was assessed by reverse transcription polymerase chain reaction (RT-PCR) or next-generation sequencing (NGS), but was not used to modify postinduction therapy. Early T-cell precursor (ETP) status was determined by flow cytometry. Cases with sufficient diagnostic DNA were retrospectively evaluated by targeted NGS of known genetic drivers of T-ALL, including Notch, PI3K, and Ras pathway genes.

RESULTS

The 5-year event-free survival (EFS) and overall survival (OS) for patients with T-ALL was 81% (95% CI, 73-87%) and 90% (95% CI, 83-94%), respectively. ETP phenotype was associated with failure to achieve complete remission, but not with inferior OS. Low end-induction MRD (<10-4 ) was associated with superior disease-free survival (DFS). Pathogenic mutations of the PI3K pathway were mutually exclusive of ETP phenotype and were associated with inferior 5-year DFS and OS.

CONCLUSIONS

Together, our findings demonstrate that ETP phenotype, end-induction MRD, and PI3K pathway mutation status are prognostically relevant in pediatric T-ALL and should be considered for risk classification in future trials. DFCI Protocols 05-001 and 11-001 are registered at www.clinicaltrials.gov as NCT00165087 and NCT01574274, respectively.

Pluripotent Stem Cells: Cancer Study, Therapy, and Vaccination

INTRODUCTION

Pluripotent stem cells (PSCs) are promising tools for modern regenerative medicine applications because of their stemness properties, which include unlimited self-renewal and the ability to differentiate into all cell types in the body. Evidence suggests that a rare population of cells within a tumor, termed cancer stem cells (CSCs), exhibit stemness and phenotypic plasticity properties that are primarily responsible for resistance to chemotherapy, radiotherapy, metastasis, cancer development, and tumor relapse. Different therapeutic approaches that target CSCs have been developed for tumor eradication.

RESULTS AND DISCUSSION

In this review, we first provide an overview of different viewpoints about the origin of CSCs. Particular attention has been paid to views believe that CSCs are probably appeared through dysregulation of very small embryonic-like stem cells (VSELs) which reside in various tissues as the main candidate for tissue-specific stem cells. The expression of pluripotency markers in these two types of cells can strengthen the validity of this theory. In this regard, we discuss the common properties of CSCs and PSCs, and highlight the potential of PSCs in cancer studies, therapeutic applications, as well as educating the immune system against CSCs.

CONCLUSION

In conclusion, the resemblance of CSCs to PSCs can provide an appropriate source of CSC-specific antigens through cultivation of PSCs which brings to light promising ideas for prophylactic and therapeutic cancer vaccine development.

Normal Hematopoiesis Is a Balancing Act of Self-Renewal and Regeneration

The hematopoietic system is highly organized to maintain its functional integrity and to meet lifelong organismal demands. Hematopoietic stem cells (HSCs) must balance self-renewal with differentiation and the regeneration of the blood system. It is a complex balancing act between these competing HSC functions. Although highly quiescent at steady state, HSCs become activated in response to inflammatory cytokines and regenerative challenges. This activation phase leads to many intrinsic stresses such as replicative, metabolic, and oxidative stress, which can cause functional decline, impaired self-renewal, and exhaustion of HSCs. To cope with these insults, HSCs use both built-in and emergency-triggered stress-response mechanisms to maintain homeostasis and to defend against disease development. In this review, we discuss how the hematopoietic system operates in steady state and stress conditions, what strategies are used to maintain functional integrity, and how deregulation in the balance between self-renewal and regeneration can drive malignant transformation.

Crosstalk between Hedgehog pathway and the glucocorticoid receptor pathway as a basis for combination therapy in T-cell acute lymphoblastic leukemia

Notwithstanding intensified therapy, a considerable fraction of T-cell acute lymphoblastic leukemia (T-ALL) patients face a dismal prognosis due to primary resistance to treatment and relapse, raising the need for more efficient and targeted therapies. Hedgehog (HH) signaling is a major developmental pathway frequently deregulated in cancer, for which a role in T-ALL is emerging. Mounting evidence suggests that ligand-independent activation of HH pathway occurs in cancer including T-ALL, emphasizing the necessity of dissecting the complex interplay between HH and other signaling pathways regulating activation. In this work, we present a therapeutically relevant crosstalk between HH signaling and the glucocorticoid receptor (NR3C1) pathway acting at the level of GLI1 transcription factor. GLI inhibitor GANT61 and dexamethasone were shown to exert a synergistic anti-leukemic effect in vitro in T-ALL cell lines and patient-derived xenografts. Mechanistically, dexamethasone-activated NR3C1 impaired GLI1 function by dynamically modulating the recruitment of PCAF acetyltransferase and HDAC1 deacetylase. Increased GLI1 acetylation was associated with compromised transcriptional activity and reduced protein stability. In summary, our study identifies a novel crosstalk between GLI1 and NR3C1 signaling pathway which could be exploited in HH-dependent malignancies to increase therapeutic efficacy.

GANT61 Reduces Hedgehog Molecule (GLI1) Expression and Promotes Apoptosis in Metastatic Oral Squamous Cell Carcinoma Cells

Due to its importance in the pathogenesis of oral squamous cell carcinoma (OSCC), the Hedgehog (HH) pathway is considered a potential therapeutic target. We investigated the effects of GANT61, a GLI inhibitor, on HH gene expression, as well as on metastatic OSCC cell proliferation and death. Following culture in DMEM medium, cytotoxicity of GANT61 against different tumor and non-tumor cell types was assessed by alamarBlue assays. Cytotoxicity analysis revealed that the metastatic HSC3 cell line was the most sensitive (IC₅₀: 36 µM) to the tested compound. The compound’s effects on the expression of HH pathways components were analyzed by qPCR and Western blot; cell viability was analyzed by trypan blue assay and flow cytometry were used to investigate cell cycle phase, morphology, and death patterns in HSC3 cells. A significant reduction in mRNA levels of the GLI1 transcription factor was found after 12 h of treatment withGANT61. Protein expression levels of other HH pathway components (PTCH1, SHH, and Gli1) and HSC3 cell viability also decreased after 24 h of treatment. Cell cycle analysis and death pattern evaluations revealed significantly increased nuclear fragmentation in sub-G1 phase, as well as cell death due to apoptosis. In conclusion, the significantly reduced GLI1 gene expression seen in response to the GLI inhibitor indicates diminished downstream activation in HH pathway components. GANT61 significantly reduced cell viability in the metastatic cell line of OSCC and promoted a significant increase in nuclear fragmentation and cell death by apoptosis.

Genetic Engineering of Zebrafish in Cancer Research

Zebrafish (Danio rerio) is an excellent model to study a wide diversity of human cancers. In this review, we provide an overview of the genetic and reverse genetic toolbox allowing the generation of zebrafish lines that develop tumors. The large spectrum of genetic tools enables the engineering of zebrafish lines harboring precise genetic alterations found in human patients, the generation of zebrafish carrying somatic or germline inheritable mutations or zebrafish showing conditional expression of the oncogenic mutations. Comparative transcriptomics demonstrate that many of the zebrafish tumors share molecular signatures similar to those found in human cancers. Thus, zebrafish cancer models provide a unique in vivo platform to investigate cancer initiation and progression at the molecular and cellular levels, to identify novel genes involved in tumorigenesis as well as to contemplate new therapeutic strategies.

Cross-talk between GLI transcription factors and FOXC1 promotes T-cell acute lymphoblastic leukemia dissemination

T-cell acute lymphoblastic leukemia (T-ALL) is a highly malignant pediatric leukemia, where few therapeutic options are available for patients which relapse. We find that therapeutic targeting of GLI transcription factors by GANT-61 is particularly effective against NOTCH1 unmutated T-ALL cells. Investigation of the functional role of GLI1 disclosed that it contributes to T-ALL cell proliferation, survival, and dissemination through the modulation of AKT and CXCR4 signaling pathways. Decreased CXCR4 signaling following GLI1 inactivation was found to be prevalently due to post-transcriptional mechanisms including altered serine 339 CXCR4 phosphorylation and cortactin levels. We also identify a novel cross-talk between GLI transcription factors and FOXC1. Indeed, GLI factors can activate the expression of FOXC1 which is able to stabilize GLI1/2 protein levels through attenuation of their ubiquitination. Further, we find that prolonged GLI1 deficiency has a double-edged role in T-ALL progression favoring disease dissemination through the activation of a putative AKT/FOXC1/GLI2 axis. These findings have clinical significance as T-ALL patients with extensive central nervous system dissemination show low GLI1 transcript levels. Further, T-ALL patients having a GLI2-based Hedgehog activation signature are associated with poor survival. Together, these findings support a rationale for targeting the FOXC1/AKT axis to prevent GLI-dependent oncogenic Hedgehog signaling.

Exploiting the Therapeutic Interaction of WNT Pathway Activation and Asparaginase for Colorectal Cancer Therapy

Colorectal cancer is driven by mutations that activate canonical WNT/β-catenin signaling, but inhibiting WNT has significant on-target toxicity, and there are no approved therapies targeting dominant oncogenic drivers. We recently found that activating a β-catenin-independent branch of WNT signaling that inhibits GSK3-dependent protein degradation induces asparaginase sensitivity in drug-resistant leukemias. To test predictions from our model, we turned to colorectal cancer because these cancers can have WNT-activating mutations that function either upstream (i.e., R-spondin fusions) or downstream (APC or β-catenin mutations) of GSK3, thus allowing WNT/β-catenin and WNT-induced asparaginase sensitivity to be unlinked genetically. We found that asparaginase had little efficacy in APC or β-catenin-mutant colorectal cancer, but was profoundly toxic in the setting of R-spondin fusions. Pharmacologic GSK3α inhibition was sufficient for asparaginase sensitization in APC or β-catenin-mutant colorectal cancer, but not in normal intestinal progenitors. Our findings demonstrate that WNT-induced therapeutic vulnerabilities can be exploited for colorectal cancer therapy. SIGNIFICANCE: Solid tumors are thought to be asparaginase-resistant via de novo asparagine synthesis. In leukemia, GSK3α-dependent protein degradation, a catabolic amino acid source, mediates asparaginase resistance. We found that asparaginase is profoundly toxic to colorectal cancers with WNT-activating mutations that inhibit GSK3. Aberrant WNT activation can provide a therapeutic vulnerability in colorectal cancer.See related commentary by Davidsen and Sullivan, p. 1632.This article is highlighted in the In This Issue feature, p. 1611.

PRL3 enhances T-cell acute lymphoblastic leukemia growth through suppressing T-cell signaling pathways and apoptosis

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes and is largely driven by the NOTCH/MYC pathway. Yet, additional oncogenic drivers are required for transformation. Here, we identify protein tyrosine phosphatase type 4 A3 (PRL3) as a collaborating oncogenic driver in T-ALL. PRL3 is expressed in a large fraction of primary human T-ALLs and is commonly co-amplified with MYC. PRL3 also synergized with MYC to initiate early-onset ALL in transgenic zebrafish and was required for human T-ALL growth and maintenance. Mass spectrometry phosphoproteomic analysis and mechanistic studies uncovered that PRL3 suppresses downstream T cell phosphorylation signaling pathways, including those modulated by VAV1, and subsequently suppresses apoptosis in leukemia cells. Taken together, our studies have identified new roles for PRL3 as a collaborating oncogenic driver in human T-ALL and suggest that therapeutic targeting of the PRL3 phosphatase will likely be a useful treatment strategy for T-ALL.

Top Notch Targeting Strategies in Cancer: A Detailed Overview of Recent Insights and Current Perspectives

Evolutionarily conserved Notch plays a critical role in embryonic development and cellular self-renewal. It has both tumour suppressor and oncogenic activity, the latter of which is widely described. Notch-activating mutations are associated with haematological malignancies and several solid tumours including breast, lung and adenoid cystic carcinoma. Moreover, upregulation of Notch receptors and ligands and aberrant Notch signalling is frequently observed in cancer. It is involved in cancer hallmarks including proliferation, survival, migration, angiogenesis, cancer stem cell renewal, metastasis and drug resistance. It is a key component of cell-to-cell interactions between cancer cells and cells of the tumour microenvironment, such as endothelial cells, immune cells and fibroblasts. Notch displays diverse crosstalk with many other oncogenic signalling pathways, and may drive acquired resistance to targeted therapies as well as resistance to standard chemo/radiation therapy. The past 10 years have seen the emergence of different classes of drugs therapeutically targeting Notch including receptor/ligand antibodies, gamma secretase inhibitors (GSI) and most recently, the development of Notch transcription complex inhibitors. It is an exciting time for Notch research with over 70 cancer clinical trials registered and the first-ever Phase III trial of a Notch GSI, nirogacestat, currently at the recruitment stage.

Association of TLX1 gene polymorphisms with the risk of acute lymphoblastic leukemia and B lineage acute lymphoblastic leukemia in Han Chinese children

Background

Studies on gene polymorphism association are centered on childhood acute lymphoblastic leukemia (ALL), a common hematological malignancy in children younger than 16 years. Single‐nucleotide polymorphisms (SNPs) in some genes, such as ARID5B and CDKN2B, are associated with the risk of childhood ALL. T‐cell leukemia homeobox 1 (TLX1), a member of the HOX gene family, was identified based on its abnormal expression in T‐lineage leukemia. This study aimed to determine whether TLX1 is associated with B‐ALL and which SNP plays a significant role in ALL.

Methods

A total of 217 cases of ALL and 241 controls were included in this study. Six tag SNPs (rs75329544, rs946328, rs12415670, rs2075879, rs17113735, and rs1051723) were selected, and genotyping was carried out on Sequenom MassARRAY platform.

Results

Rs17113735 was possibly the risk locus associated with increased risk for ALL, whereas rs946328 was possibly associated with decreased risk for ALL. Moreover, rs17113735 was likely to be the risk locus for B‐cell ALL (B‐ALL), and rs2075879 was associated with decreased risk for B‐ALL (P < .05). All SNPs in the two sample types (ALL and B‐ALL samples) demonstrated linkage disequilibrium except between rs75329544 and rs2075879. Haplotype analysis showed no significant difference between the cases and controls in the two sample types.

Conclusion

TLX1 gene polymorphisms are associated with ALL (rs17113735 and rs946328) and possibly play a significant role in B‐ALL (rs17113735 and rs2075879). This work provides a reference for the diagnosis and therapy of this disease.

Zebrafish patient avatars in cancer biology and precision cancer therapy

In precision oncology, two major strategies are being pursued for predicting clinically relevant tumour behaviours, such as treatment response and emergence of drug resistance: inference based on genomic, transcriptomic, epigenomic and/or proteomic analysis of patient samples, and phenotypic assays in personalized cancer avatars. The latter approach has historically relied on in vivo mouse xenografts and in vitro organoids or 2D cell cultures. Recent progress in rapid combinatorial genetic modelling, the development of a genetically immunocompromised strain for xenotransplantation of human patient samples in adult zebrafish and the first clinical trial using xenotransplantation in zebrafish larvae for phenotypic testing of drug response bring this tiny vertebrate to the forefront of the precision medicine arena. In this Review, we discuss advances in transgenic and transplantation-based zebrafish cancer avatars, and how these models compare with and complement mouse xenografts and human organoids. We also outline the unique opportunities that these different models present for prediction studies and current challenges they face for future clinical deployment.

Pediatric Cancer Models in Zebrafish

Pediatric cancer is a leading cause of death in children and adolescents. Improvements in pediatric cancer treatment that include the alleviation of long-term adverse effects require a deeper understanding of the genetic, epigenetic, and developmental factors driving these cancers. Here, we review how the unique attributes of the zebrafish model system in embryology, imaging, and scalability have been used to identify new mechanisms of tumor initiation, progression, and relapse and for drug discovery. We focus on zebrafish models of leukemias, neural tumors and sarcomas - the most common and difficult childhood cancers to treat.

Chidamide Inhibits Glioma Cells by Increasing Oxidative Stress via the miRNA-338-5p Regulation of Hedgehog Signaling

Objective

Chidamide has a broad spectrum of antitumor activity but its function on glioma remains unknown. The increase of reactive oxygen species (ROS) and reactive nitrogen species (RNS) may control glioma risk by promoting its apoptosis and necrosis. Hedgehog pathway is crucial to glioma cell proliferation and controls ROS production. We aimed to explore the effects of chidamide on the levels of miR-338-5p (glioma cell inhibitor), which may regulate Hedgehog signaling, resulting in the changes of RNS. Materials and Methods. Migration and invasion activities of glioma cells were measured by using the Transwell chamber assay. The expression levels of Sonic Hedgehog (Shh), Indian Hedgehog (Ihh), Desert Hedgehog (Dhh), miR-338-5p, and related molecules were detected by using real-time PCR (RT-PCR) and or Western Blot in U87 and HS683 glioma cells. The effects of chidamide on these molecules were measured by using the miR-338-5p inhibitor or mimics in U87 and HS683 glioma cell lines. ROS and RNS were measured by DCF DA and DAF-FM DA fluorescence. Biomarkers of oxidative stress were measured by using a corresponding kit. Apoptosis and necrosis rates were measured by using flow cytometry.

Results

Chidamide inhibited the growth rate, migration, and invasion of human malignant glioma cells and increased the level of miR-338-5p. miR-338-5p inhibitor or mimics increased or inhibited the growth rate of U87 and HS683 glioma cells. Chidamide inhibited the levels of Shh, Ihh, migration protein E-cadherin, and invading protein MMP-2. The increase in the level of Shh and Ihh led to the reduction in the ROS and RNS levels. miR-338-5p inhibitor or mimics also showed a promoting or inhibitory function for the levels of Shh and Ihh. Furthermore, miR-338-5p mimics and inhibitor inhibited or promoted the migration and invasion of the glioma cells (P < 0.05). Evaluated levels of miR-338-5p increased oxidative stress level and apoptosis and necrosis rate by regulating the levels of biomarkers of oxidative stress (P < 0.05). Evaluated levels of miR-338-5p increased oxidative stress level and apoptosis and necrosis rate by regulating the levels of biomarkers of oxidative stress (

Conclusion

Chidamide inhibits glioma cells by increasing oxidative stress via the miRNA-338-5p regulation of Hedgehog signaling. Chidamide may be a potential drug in the prevention of glioma development.

Inhibition of hedgehog signaling by stereochemically defined des-triazole itraconazole analogues

Dysregulation of the hedgehog (Hh) signaling pathway is associated with cancer occurrence and development in various malignancies. Previous structure-activity relationships (SAR) studies have provided potent Itraconazole (ITZ) analogues as Hh pathway antagonists. To further expand on our SAR for the ITZ scaffold, we synthesized and evaluated a series of compounds focused on replacing the triazole. Our results demonstrate that the triazole region is amenable to modification to a variety of different moieties; with a single methyl group representing the most favorable substituent. In addition, nonpolar substituents were more active than polar substituents. These SAR results provide valuable insight into the continued exploration of ITZ analogues as Hh pathway antagonists.

Truncated Itraconazole Analogues Exhibiting Potent Anti-Hedgehog Activity and Improved Drug-like Properties

We conducted a structure-activity relationship study to explore simplified analogues of the itraconazole (ITZ) scaffold for their ability to inhibit the hedgehog (Hh) signaling pathway. These analogues were based on exploring the effects of chemical modifications to the linker and triazolone/side chain region of ITZ. Analogue 11 was identified as the most potent compound in our first generation, with an IC₅₀ value of 81 nM in a murine Hh-dependent basal cell carcinoma. Metabolic identification studies led us to identify truncated piperazine (26) as the major metabolite in human liver microsomes (HLMs) and an improved Hh pathway inhibitor (IC₅₀ = 22 nM). This work verifies that continued truncation of the ITZ scaffold is a practical method to maintain potent anti-Hh activity while also reducing the molecular weight for the ITZ scaffold and achieving improved pharmacokinetic properties.

Suppressing Hedgehog signaling reverses drug resistance of refractory acute myeloid leukemia

Background

Hedgehog (Hh) signaling is involved in the pathogenesis of tumors. By performing gene chip analysis, we predicted that Hh signaling might regulate multiple downstream pathways in acute myeloid leukemia (AML).

Methods

In this study, the potential role of the Hh pathway in refractory AML, and the impact of Hh expression on clinical prognosis were examined. We also investigated the role of the Hh inhibitor NVP-LDE225 in reversing drug resistance of refractory primary AML cells in vitro and the roles of multiple drug-resistant HL60/Adriamycin-resistant cells in vitro and in vivo (in a xenograft mouse model). Finally, we explored the underlying mechanisms.

Results

Hh pathway was highly active in chemotherapy-resistant AML cells; by contrast, activation was less pronounced in chemosensitive cells and non-refractory primary cells. Strong activation of this pathway was associated with higher recurrence rates and poorer relapse-free and overall survival. NVP-LDE225 inhibited MRP1 protein expression, increased intracellular accumulation of Adriamycin, and reversed chemotherapeutic resistance. These effects were likely mediated through inhibition of the IGF-1R/Akt/MRP1 pathway. In the AML xenograft mouse model, NVP-LDE225 plus Adriamycin resulted in marked tumor regression.

Conclusion

These findings suggest that targeting the Hh pathway might be a therapeutic avenue for overcoming MDR resistance and preventing refractory AML.

Wnt, Notch, and TGF-β Pathways Impinge on Hedgehog Signaling Complexity: An Open Window on Cancer

Constitutive activation of the Hedgehog (Hh) signaling pathway is associated with increased risk of developing several malignancies. The biological and pathogenic importance of Hh signaling emphasizes the need to control its action tightly, both physiologically and therapeutically. Evidence of crosstalk between Hh and other signaling pathways is reported in many tumor types. Here, we provide an overview of the current knowledge about the communication between Hh and major signaling pathways, such as Notch, Wnt, and transforming growth factor β (TGF-β), which play critical roles in both embryonic and adult life. When these pathways are unbalanced, impaired crosstalk contributes to disease development. It is reported that more than one of these pathways are active in different type of tumors, at the same time. Therefore, starting from a plethora of stimuli that activate multiple signaling pathways, we describe the signals that preferentially converge on the Hh signaling cascade that influence its activity. Moreover, we highlight several connection points between Hh and Notch, Wnt, or TGF-β pathways, showing a reciprocal synergism that contributes to tumorigenesis, supporting a more malignant behavior by tumor cells, such as in leukemia and brain tumors. Understanding the importance of these molecular interlinking networks will provide a rational basis for combined anticancer drug development.

Genomic testing, tumor microenvironment and targeted therapy of Hedgehog-related human cancers

Hedgehog signals are transduced through Patched receptors to the Smoothened (SMO)-SUFU-GLI and SMO-Gi-RhoA signaling cascades. MTOR-S6K1 and MEK-ERK signals are also transduced to GLI activators through post-translational modifications. The GLI transcription network up-regulates target genes, such as BCL2, FOXA2, FOXE1, FOXF1, FOXL1, FOXM1, GLI1, HHIP, PTCH1 and WNT2B, in a cellular context-dependent manner. Aberrant Hedgehog signaling in tumor cells leads to self-renewal, survival, proliferation and invasion. Paracrine Hedgehog signaling in the tumor microenvironment (TME), which harbors cancer-associated fibroblasts, leads to angiogenesis, fibrosis, immune evasion and neuropathic pain. Hedgehog-related genetic alterations occur frequently in basal cell carcinoma (BCC) (85%) and Sonic Hedgehog (SHH)-subgroup medulloblastoma (87%) and less frequently in breast cancer, colorectal cancer, gastric cancer, pancreatic cancer, non-small-cell lung cancer (NSCLC) and ovarian cancer. Among investigational SMO inhibitors, vismodegib and sonidegib are approved for the treatment of patients with BCC, and glasdegib is approved for the treatment of patients with acute myeloid leukemia (AML). Resistance to SMO inhibitors is caused by acquired SMO mutations, SUFU deletions, GLI2 amplification, other by-passing mechanisms of GLI activation and WNT/β-catenin signaling activation. GLI-DNA-interaction inhibitors (glabrescione B and GANT61), GLI2 destabilizers (arsenic trioxide and pirfenidone) and a GLI-deacetylation inhibitor (4SC-202) were shown to block GLI-dependent transcription and tumorigenesis in preclinical studies. By contrast, SMO inhibitors can remodel the immunosuppressive TME that is dominated by M2-like tumor-associated macrophages (M2-TAMs), myeloid-derived suppressor cells and regulatory T cells, and thus, a Phase I/II clinical trial of the immune checkpoint inhibitor pembrolizumab with or without vismodegib in BCC patients is ongoing.

Synthetic Lethality of Wnt Pathway Activation and Asparaginase in Drug-Resistant Acute Leukemias

Resistance to asparaginase, an antileukemic enzyme that depletes asparagine, is a common clinical problem. Using a genome-wide CRISPR/Cas9 screen, we found a synthetic lethal interaction between Wnt pathway activation and asparaginase in acute leukemias resistant to this enzyme. Wnt pathway activation induced asparaginase sensitivity in distinct treatment-resistant subtypes of acute leukemia, but not in normal hematopoietic progenitors. Sensitization to asparaginase was mediated by Wnt-dependent stabilization of proteins (Wnt/STOP), which inhibits glycogen synthase kinase 3 (GSK3)-dependent protein ubiquitination and proteasomal degradation, a catabolic source of asparagine. Inhibiting the alpha isoform of GSK3 phenocopied this effect, and pharmacologic GSK3α inhibition profoundly sensitized drug-resistant leukemias to asparaginase. Our findings provide a molecular rationale for activation of Wnt/STOP signaling to improve the therapeutic index of asparaginase.

Zebrafish disease models in hematology: Highlights on biological and translational impact

Zebrafish (Danio rerio) has proven to be a versatile and reliable in vivo experimental model to study human hematopoiesis and hematological malignancies. As vertebrates, zebrafish has significant anatomical and biological similarities to humans, including the hematopoietic system. The powerful genome editing and genome-wide forward genetic screening tools have generated models that recapitulate human malignant hematopoietic pathologies in zebrafish and unravel cellular mechanisms involved in these diseases. Moreover, the use of zebrafish models in large-scale chemical screens has allowed the identification of new molecular targets and the design of alternative therapies. In this review we summarize the recent achievements in hematological research that highlight the power of the zebrafish model for discovery of new therapeutic molecules. We believe that the model is ready to give an immediate translational impact into the clinic.

PRC2 loss induces chemoresistance by repressing apoptosis in T cell acute lymphoblastic leukemia

The tendency of mitochondria to undergo or resist BCL2-controlled apoptosis (so-called mitochondrial priming) is a powerful predictor of response to cytotoxic chemotherapy. Fully exploiting this finding will require unraveling the molecular genetics underlying phenotypic variability in mitochondrial priming. Here, we report that mitochondrial apoptosis resistance in T cell acute lymphoblastic leukemia (T-ALL) is mediated by inactivation of polycomb repressive complex 2 (PRC2). In T-ALL clinical specimens, loss-of-function mutations of PRC2 core components (EZH2, EED, or SUZ12) were associated with mitochondrial apoptosis resistance. In T-ALL cells, PRC2 depletion induced resistance to apoptosis induction by multiple chemotherapeutics with distinct mechanisms of action. PRC2 loss induced apoptosis resistance via transcriptional up-regulation of the LIM domain transcription factor CRIP2 and downstream up-regulation of the mitochondrial chaperone TRAP1 These findings demonstrate the importance of mitochondrial apoptotic priming as a prognostic factor in T-ALL and implicate mitochondrial chaperone function as a molecular determinant of chemotherapy response.

Hedgehog Signaling in Cancer: A Prospective Therapeutic Target for Eradicating Cancer Stem Cells

The Hedgehog (Hh) pathway is a signaling cascade that plays a crucial role in many fundamental processes, including embryonic development and tissue homeostasis. Moreover, emerging evidence has suggested that aberrant activation of Hh is associated with neoplastic transformations, malignant tumors, and drug resistance of a multitude of cancers. At the molecular level, it has been shown that Hh signaling drives the progression of cancers by regulating cancer cell proliferation, malignancy, metastasis, and the expansion of cancer stem cells (CSCs). Thus, a comprehensive understanding of Hh signaling during tumorigenesis and development of chemoresistance is necessary in order to identify potential therapeutic strategies to target various human cancers and their relapse. In this review, we discuss the molecular basis of the Hh signaling pathway and its abnormal activation in several types of human cancers. We also highlight the clinical development of Hh signaling inhibitors for cancer therapy as well as CSC-targeted therapy.

Widespread Expression of Hedgehog Pathway Components in a Large Panel of Human Tumor Cells and Inhibition of Tumor Growth by GANT61: Implications for Cancer Therapy

The sonic Hedgehog/GLI signaling pathway (HH) is critical for maintaining tissue polarity in development and contributes to tumor stemness. Transcription factors GLI1–3 are the downstream effectors of HH and activate oncogenic targets. To explore the completeness of the expression of HH components in tumor cells, we performed a screen for all HH proteins in a wide spectrum of 56 tumor cell lines of various origin using Western blot analysis. Generally, all HH proteins were expressed. Important factors GLI1 and GLI2 were always expressed, only exceptionally one of them was lowered, suggesting the functionality of HH in all tumors tested. We determined the effect of a GLI inhibitor GANT61 on proliferation in 16 chosen cell lines. More than half of tumor cells were sensitive to GANT61 to various extents. GANT61 killed the sensitive cells through apoptosis. The inhibition of reporter activity containing 12xGLI consensus sites by GANT61 and cyclopamine roughly correlated with cell proliferation influenced by GANT61. Our results recognize the sensitivity of tumor cell types to GANT61 in cell culture and support a critical role for GLI factors in tumor progression through restraining apoptosis. The use of GANT61 in combined targeted therapy of sensitive tumors, such as melanomas, seems to be immensely helpful.

CRISPR/Cas9 disease models in zebrafish and Xenopus: The genetic renaissance of fish and frogs

The speed by which clinical genomics is currently identifying novel potentially pathogenic variants is outperforming the speed by which these can be functionally (genotype-phenotype) annotated in animal disease models. However, over the past few years the emergence of CRISPR/Cas9 as a straight-forward genome editing technology has revolutionized disease modeling in vertebrate non-mammalian model organisms such as zebrafish, medaka and Xenopus. It is now finally possible, by CRISPR/Cas9, to rapidly establish clinically relevant disease models in these organisms. Interestingly, these can provide both cost-effective genotype-phenotype correlations for gene-(variants) and genomic rearrangements obtained from clinical practice, as well as be exploited to perform translational research to improve prospects of disease afflicted patients. In this review, we show an extensive overview of these new CRISPR/Cas9-mediated disease models and provide future prospects that will allow increasingly accurate modeling of human disease in zebrafish, medaka and Xenopus.

Targeted genome editing in acute lymphoblastic leukemia: a review

Background

Genome editing technologies offers new opportunities for tackling diseases such as acute lymphoblastic leukemia (ALL) that have been beyond the reach of previous therapies.

Results

We show how the recent availability of genome-editing tools such as CRISPR-Cas9 are an important means of advancing functional studies of ALL through the incorporation, elimination and modification of somatic mutations and fusion genes in cell lines and mouse models. These tools not only broaden the understanding of the involvement of various genetic alterations in the pathogenesis of the disease but also identify new therapeutic targets for future clinical trials.

Conclusions

New approaches including CRISPR-Cas9 are crucial for functional studies of genetic aberrations driving cancer progression, and that may be responsible for treatment resistance and relapses. By using this approach, diseases can be more faithfully reproduced and new therapeutic targets and approaches found.