Coordinate activation of Shh and PI3K signaling in PTEN-deficient glioblastoma: new therapeutic opportunities

Novel strategies to overcome chemoresistance in human glioblastoma

Temozolomide (TMZ) is currently the first-line chemotherapeutic agent for the treatment of glioblastoma multiforme (GBM). However, the inherent heterogeneity of GBM often results in suboptimal outcomes, particularly due to varying degrees of resistance to TMZ. Over the past several decades, O6-methylguanine-DNA methyltransferase (MGMT)-mediated DNA repair pathway has been extensively investigated as a target to overcome TMZ resistance. Nonetheless, the combination of small molecule covalent MGMT inhibitors with TMZ and other chemotherapeutic agents has frequently led to adverse clinical effects. Recently, additional mechanisms contributing to TMZ resistance have been identified, including epidermal growth factor receptor (EGFR) mutations, overactivation of intracellular signalling pathways, energy metabolism reprogramming or survival autophagy, and changes in tumor microenvironment (TME). These findings suggest that novel therapeutic strategies targeting these mechanisms hold promise for overcoming TMZ resistance in GBM patients. In this review, we summarize the latest advancements in understanding the mechanisms underlying intrinsic and acquired TMZ resistance. Additionally, we compile various small-molecule compounds with potential to mitigate chemoresistance in GBM. These mechanism-based compounds may enhance the sensitivity of GBM to TMZ and related chemotherapeutic agents, thereby improving overall survival rates in clinical practice.

Sonic hedgehog signalling pathway in CNS tumours: its role and therapeutic implications

CNS tumours encompass a diverse group of neoplasms with significant morbidity and mortality. The SHH signalling pathway plays a critical role in the pathogenesis of several CNS tumours, including gliomas, medulloblastomas and others. By influencing cellular proliferation, differentiation and migration in CNS tumours, the SHH pathway has emerged as a promising target for therapeutic intervention. Current strategies such as vismodegib and sonidegib have shown efficacy in targeting SHH pathway activation. However, challenges such as resistance mechanisms and paradoxical effects observed in clinical settings underscore the complexity of effectively targeting this pathway. Advances in gene editing technologies, particularly CRISPR/Cas9, have provided valuable tools for studying SHH pathway biology, validating therapeutic targets and exploring novel treatment modalities. These innovations have paved the way for a better understanding of pathway dynamics and the development of more precise therapeutic interventions. In addition, the identification and validation of biomarkers of SHH pathway activation are critical to guide clinical decision making and improve patient outcomes. Molecular profiling and biomarker discovery efforts are critical steps towards personalised medicine approaches in the treatment of SHH pathway-associated CNS tumours. While significant progress has been made in understanding the role of the SHH pathway in CNS tumorigenesis, ongoing research is essential to overcome current therapeutic challenges and refine treatment strategies. The integration of molecular insights with advanced technologies and clinical expertise holds great promise for developing more effective and personalised therapies for patients with SHH pathway-driven CNS tumours.

Prognostic Significance of Psoas Muscle Index in Unresectable Hepatocellular Carcinoma: Comparative Analysis of Lenvatinib and Atezolizumab Plus Bevacizumab

Background and Aims: Skeletal muscle loss has been identified as a prognostic factor in patients with unresectable hepatocellular carcinoma (uHCC) undergoing treatment with lenvatinib (LEN). While atezolizumab plus bevacizumab (ATZ-BEV) is recommended as first-line therapy for uHCC, the impact of skeletal muscle loss in these patients remains unclear. Methods: We enrolled 97 patients treated with either LEN or ATZ-BEV as their first-line therapy and divided them into two groups based on the presence or absence of a low psoas muscle index (low PMI) before treatment. We compared patient characteristics and overall survival (OS) between the groups. Additionally, we investigated the transition of the PMI during drug therapy, specifically before treatment, at the initial evaluation, and after the end of treatment. Results: Seventy percent of patients in the LEN group and seventy-one percent in the ATZ-BEV group had a low PMI. Multivariate analysis across all patients revealed a low PMI (hazard ratio [HR] 3.25, p = 0.0004) as a prognostic factor for OS. The PMI decreased more in the LEN group compared to the ATZ-BEV group. In the Barcelona Clinic Liver Cancer-C group, the OS of ATZ-BEV therapy was significantly better than that of LEN therapy when a low PMI was present (p = 0.046). Conclusions: A low PMI emerges as a significant prognostic factor in uHCC patients undergoing drug therapy, not only in LEN therapy but also in ATZ-BEV therapy. Additionally, ATZ-BEV therapy may be more favorable for sarcopenic patients with advanced HCC stages.

Interactions between hedgehog signaling pathway and the complex tumor microenvironment in breast cancer: current knowledge and therapeutic promises

Breast cancer ranks as one of the most common malignancies among women, with its prognosis and therapeutic efficacy heavily influenced by factors associated with the tumor cell biology, particularly the tumor microenvironment (TME). The diverse elements of the TME are engaged in dynamic bidirectional signaling interactions with various pathways, which together dictate the growth, invasiveness, and metastatic potential of breast cancer. The Hedgehog (Hh) signaling pathway, first identified in Drosophila, has been established as playing a critical role in human development and disease. Notably, the dysregulation of the Hh pathway is recognized as a major driver in the initiation, progression, and metastasis of breast cancer. Consequently, elucidating the mechanisms by which the Hh pathway interacts with the distinct components of the breast cancer TME is essential for comprehensively evaluating the link between Hh pathway activation and breast cancer risk. This understanding is also imperative for devising novel targeted therapeutic strategies and preventive measures against breast cancer. In this review, we delineate the current understanding of the impact of Hh pathway perturbations on the breast cancer TME, including the intricate and complex network of intersecting signaling cascades. Additionally, we focus on the therapeutic promise and clinical challenges of Hh pathway inhibitors that target the TME, providing insights into their potential clinical utility and the obstacles that must be overcome to harness their full therapeutic potential.

High-throughput neural stem cell-based drug screening identifies S6K1 inhibition as a selective vulnerability in sonic hedgehog-medulloblastoma

BACKGROUND

Medulloblastoma (MB) is one of the most common malignant brain tumors in children. Current treatments have increased overall survival but can lead to devastating side effects and late complications in survivors, emphasizing the need for new, improved targeted therapies that specifically eliminate tumor cells while sparing the normally developing brain.

METHODS

Here, we used a sonic hedgehog (SHH)-MB model based on a patient-derived neuroepithelial stem cell system for an unbiased high-throughput screen with a library of 172 compounds with known targets. Compounds were evaluated in both healthy neural stem cells (NSCs) and tumor cells derived from the same patient. Based on the difference of cell viability and drug sensitivity score between normal cells and tumor cells, hit compounds were selected and further validated in vitro and in vivo.

RESULTS

We identified PF4708671 (S6K1 inhibitor) as a potential agent that selectively targets SHH-driven MB tumor cells while sparing NSCs and differentiated neurons. Subsequent validation studies confirmed that PF4708671 inhibited the growth of SHH-MB tumor cells both in vitro and in vivo, and that knockdown of S6K1 resulted in reduced tumor formation.

CONCLUSIONS

Overall, our results suggest that inhibition of S6K1 specifically affects tumor growth, whereas it has less effect on non-tumor cells. Our data also show that the NES cell platform can be used to identify potentially effective new therapies and targets for SHH-MB.

Identification of Novel GANT61 Analogs with Activity in Hedgehog Functional Assays and GLI1-Dependent Cancer Cells

Aberrant activation of hedgehog (Hh) signaling has been implicated in various cancers. Current FDA-approved inhibitors target the seven-transmembrane receptor Smoothened, but resistance to these drugs has been observed. It has been proposed that a more promising strategy to target this pathway is at the GLI1 transcription factor level. GANT61 was the first small molecule identified to directly suppress GLI-mediated activity; however, its development as a potential anti-cancer agent has been hindered by its modest activity and aqueous chemical instability. Our study aimed to identify novel GLI1 inhibitors. JChem searches identified fifty-two compounds similar to GANT61 and its active metabolite, GANT61-D. We combined high-throughput cell-based assays and molecular docking to evaluate these analogs. Five of the fifty-two GANT61 analogs inhibited activity in Hh-responsive C3H10T1/2 and Gli-reporter NIH3T3 cellular assays without cytotoxicity. Two of the GANT61 analogs, BAS 07019774 and Z27610715, reduced Gli1 mRNA expression in C3H10T1/2 cells. Treatment with BAS 07019774 significantly reduced cell viability in Hh-dependent glioblastoma and lung cancer cell lines. Molecular docking indicated that BAS 07019774 is predicted to bind to the ZF4 region of GLI1, potentially interfering with its ability to bind DNA. Our findings show promise in developing more effective and potent GLI inhibitors.

YANK2 activated by Fyn promotes glioma tumorigenesis via the mTOR-independent p70S6K activation pathway

Glioma, particularly glioblastomas (GBM), is incurable brain tumor. The most targeted receptor tyrosine kinase (RTKs) drugs did not bring benefit to GBM patients. The mechanism of glioma growth continues to be explored to find more effective treatment. Here, we reported that Ser/Thr protein kinase YANK2 (yet another kinase 2) is upregulated in glioma tissues and promotes the growth and proliferation of glioma in vitro and in vivo. Further, we confirmed that oncogene Fyn directly activated YANK2 through phosphorylation its Y110, and Fyn-mediated YANK2 phosphorylation at Y110 site promotes glioma growth by increasing its stability. Finally, YANK2 was proved to be a novel upstream kinase of p70S6K and promotes glioma growth by directly phosphorylating p70S6K at T389. Taken together, we found a new mTOR-independent p70S6K activation pathway, Fyn-YANK2-p70S6K, which promotes glioma growth, and YANK2 is a potential oncogene and serves as a novel therapeutic target for glioma.

The important regulatory roles of circRNA‑encoded proteins or peptides in cancer pathogenesis (Review)

Circular RNAs (circRNAs) represent a class of RNA molecules characterized by their covalently closed structures. There are three types of circRNAs, namely exonic circRNAs, exon‑intron circRNAs and circular intronic RNAs. To date, four distinct mechanisms have been unveiled through which circRNAs exert their functional influence, including serving as microRNA (miRNA) sponges, interacting with RNA binding proteins (RBPs), modulating parental gene transcription and acting as templates for translation. Of note, among these mechanisms, the miRNA/RBP sponge function has been the most investigated one. Recent research has uncovered the presence of various proteins or peptides encoded by circRNA. CircRNAs are translated independent of the 5' cap and 3' polyA tail, which are typical elements for linear RNA translation. Some unique elements, such as internal ribosome entry sites and N‑methyladenosine modifications, facilitate the initiation of translation. These circRNA‑encoded proteins or peptides participate in diverse signalling pathways and act as important regulators in carcinogenesis by influencing cell proliferation, migration, apoptosis and other key processes. Consequently, circRNA‑encoded proteins or peptides have great potential as therapeutic targets for anticancer drugs. The present comprehensive review aimed to systematically summarize the current understanding of circRNA‑encoded proteins or peptides and to unveil their roles in carcinogenesis.

Increasing Ciliary ARL13B Expression Drives Active and Inhibitor-Resistant Smoothened and GLI into Glioma Primary Cilia

ADP-ribosylation factor-like protein 13B (ARL13B), a regulatory GTPase and guanine exchange factor (GEF), enriches in primary cilia and promotes tumorigenesis in part by regulating Smoothened (SMO), GLI, and Sonic Hedgehog (SHH) signaling. Gliomas with increased ARL13B, SMO, and GLI2 expression are more aggressive, but the relationship to cilia is unclear. Previous studies have showed that increasing ARL13B in glioblastoma cells promoted ciliary SMO accumulation, independent of exogenous SHH addition. Here, we show that SMO accumulation is due to increased ciliary, but not extraciliary, ARL13B. Increasing ARL13B expression promotes the accumulation of both activated SMO and GLI2 in glioma cilia. ARL13B-driven increases in ciliary SMO and GLI2 are resistant to SMO inhibitors, GDC-0449, and cyclopamine. Surprisingly, ARL13B-induced changes in ciliary SMO/GLI2 did not correlate with canonical changes in downstream SHH pathway genes. However, glioma cell lines whose cilia overexpress WT but not guanine exchange factor-deficient ARL13B, display reduced INPP5e, a ciliary membrane component whose depletion may favor SMO/GLI2 enrichment. Glioma cells overexpressing ARL13B also display reduced ciliary intraflagellar transport 88 (IFT88), suggesting that altered retrograde transport could further promote SMO/GLI accumulation. Collectively, our data suggest that factors increasing ARL13B expression in glioma cells may promote both changes in ciliary membrane characteristics and IFT proteins, leading to the accumulation of drug-resistant SMO and GLI. The downstream targets and consequences of these ciliary changes require further investigation.

Lipid metabolism in malignant tumor brain metastasis: reprogramming and therapeutic potential

INTRODUCTION

Brain metastasis is a highly traumatic event in the progression of malignant tumors, often symbolizing higher mortality. Metabolic alterations are hallmarks of cancer, and the mask of lipid metabolic program rearrangement in cancer progression is gradually being unraveled.

AREAS COVERED

In this work, we reviewed clinical and fundamental studies related to lipid expression and activity changes in brain metastases originating from lung, breast, and cutaneous melanomas, respectively. Novel roles of lipid metabolic reprogramming in the development of brain metastasis from malignant tumors were identified and its potential as a therapeutic target was evaluated. Published literature and clinical studies in databases consisting of PubMed, Embase, Scopus and www.ClinicalTrials.gov from 1990 to 2022 were searched.

EXPERT OPINION

Lipid metabolic reprogramming in brain metastasis is involved in de novo lipid synthesis within low lipid availability environments, regulation of lipid uptake and storage, metabolic interactions between brain tumors and the brain microenvironment, and membrane lipid remodeling, in addition to being a second messenger for signal transduction. Although some lipid metabolism modulators work efficiently in preclinical models, there is still a long way to go from laboratory to clinic. This area of research holds assurance for the organ-targeted treatment of brain metastases through drug-regulated metabolic targets and dietary interventions.

Underlying mechanisms and clinical potential of circRNAs in glioblastoma

Glioblastoma (GBM) is the most malignant form of glioma and is difficult to diagnose, leading to high mortality rates. Circular RNAs (circRNAs) are noncoding RNAs with a covalently closed loop structure. CircRNAs are involved in various pathological processes and have been revealed to be important regulators of GBM pathogenesis. CircRNAs exert their biological effects by 4 different mechanisms: serving as sponges of microRNAs (miRNAs), serving as sponges of RNA binding proteins (RBPs), modulating parental gene transcription, and encoding functional proteins. Among the 4 mechanisms, sponging miRNAs is predominant. Their good stability, broad distribution and high specificity make circRNAs promising biomarkers for GBM diagnosis. In this paper, we summarized the current understanding of the characteristics and action mechanisms of circRNAs, illustrated the underlying regulatory mechanisms of circRNAs in GBM progression and explored the possible diagnostic role of circRNAs in GBM.

Xihuang Pill-destabilized CD133/EGFR/Akt/mTOR cascade reduces stemness enrichment of glioblastoma via the down-regulation of SOX2

BACKGROUND

Our previous study found that XHP could induce GBM cells to undergo apoptosis. A lot of evidence suggests that glioma stem-like cells (GSCs) are key factors that contribute to disease progression and poor prognosis of glioblastoma multiforme (GBM). Traditional Chinese medicine has been applied in clinical practice as a complementary and alternative therapy for glioma.

PURPOSE

To evaluate the effect and the potential molecular mechanism of Xihuang pill (XHP) on GSCs.

METHODS

UPLC-QTOF-MS analysis was used for constituent analysis of XHP. Using network pharmacology and bioinformatics methods, a molecular network targeting GSCs by the active ingredients in XHP was constructed. Cell viability, self-renewal ability, apoptosis, and GSC markers were detected by CCK-8 assay, tumor sphere formation assay and flow cytometry, respectively. The interrelationship between GSC markers (CD133 and SOX2) and key proteins of the EGFR/Akt/mTOR signaling pathway was evaluated using GEPIA and verified by western blot. A GBM cell line stably overexpressing Akt was constructed using lentivirus to evaluate the role of Akt signaling in the regulation of glioma stemness. The effect of XHP on glioma growth was analyzed by a subcutaneously transplanted glioma cell model in nude mice, hematoxylin-eosin staining was used to examine pathological changes, TUNEL staining was used to detect apoptosis in tumor tissues, and the expression of GSC markers in tumor tissues was identified by western blot and immunofluorescence.

RESULTS

Bioinformatics analysis showed that 55 matched targets were related to XHP targets and glioma stem cell targets. In addition to causing apoptosis, XHP could diminish the number of GBM 3D spheroids, the proportion of CD133-positive cells and the expression level of GSC markers (CD133 and SOX2) in vitro. Furthermore, XHP could attenuate the expression of CD133, EGFR, p-Akt, p-mTOR and SOX2 in GBM spheres. Overexpression of Akt significantly increased the expression level of SOX2, which was prohibited in the presence of XHP. XHP reduced GSC markers including CD133 and SOX2, and impeded the development of glioma growth in xenograft mouse models in vivo.

CONCLUSION

We demonstrate for the first time that XHP down-regulates stemness, restrains self-renewal and induces apoptosis in GSCs and impedes glioma growth by down-regulating SOX2 through destabilizing the CD133/EGFR/Akt/mTOR cascade.

Ribonucleotide reductase regulatory subunit M2 drives glioblastoma TMZ resistance through modulation of dNTP production

During therapy, adaptations driven by cellular plasticity are partly responsible for driving the inevitable recurrence of glioblastoma (GBM). To investigate plasticity-induced adaptation during standard-of-care chemotherapy temozolomide (TMZ), we performed in vivo single-cell RNA sequencing in patient-derived xenograft (PDX) tumors of GBM before, during, and after therapy. Comparing single-cell transcriptomic patterns identified distinct cellular populations present during TMZ therapy. Of interest was the increased expression of ribonucleotide reductase regulatory subunit M2 (RRM2), which we found to regulate dGTP and dCTP production vital for DNA damage response during TMZ therapy. Furthermore, multidimensional modeling of spatially resolved transcriptomic and metabolomic analysis in patients' tissues revealed strong correlations between RRM2 and dGTP. This supports our data that RRM2 regulates the demand for specific dNTPs during therapy. In addition, treatment with the RRM2 inhibitor 3-AP (Triapine) enhances the efficacy of TMZ therapy in PDX models. We present a previously unidentified understanding of chemoresistance through critical RRM2-mediated nucleotide production.

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.

Combined treatments with AZD5363, AZD8542, curcumin or resveratrol induce death of human glioblastoma cells by suppressing the PI3K/AKT and SHH signaling pathways

Glioblastoma (GBM) is a very aggressive tumor that presents vascularization, necrosis and is resistant to chemotherapy and radiotherapy. Current treatments are not effective eradicating GBM, thus, there is an urgent need to develop novel therapeutic strategies against GBM. AZD5363, AZD8542, curcumin and resveratrol, are widely studied for the treatment of cancer and in the present study we explored the effects of the administration of combined treatments with AZD5363, AZD8542, curcumin or resveratrol on human GBM cells. We found that the combined treatments with AZD5363+AZD8542+Curcumin and AZD8542+Curcumin+Resveratrol inhibit the PI3K/AKT and SHH survival pathways by decreasing the activity of AKT, the reduction of the expression of SMO, pP70S6k, pS6k, GLI1, p21 and p27, and the activation of caspase-3 as a marker of apoptosis. These results provide evidence that the combined treatments AZD5363+AZD8542+Curcumin and AZD8542+Curcumin+Resveratrol have the potential to be an interesting option against GBM.

Signaling pathways in brain tumors and therapeutic interventions

Brain tumors, although rare, contribute to distinct mortality and morbidity at all ages. Although there are few therapeutic options for brain tumors, enhanced biological understanding and unexampled innovations in targeted therapies and immunotherapies have considerably improved patients' prognoses. Nonetheless, the reduced response rates and unavoidable drug resistance of currently available treatment approaches have become a barrier to further improvement in brain tumor (glioma, meningioma, CNS germ cell tumors, and CNS lymphoma) treatment. Previous literature data revealed that several different signaling pathways are dysregulated in brain tumor. Importantly, a better understanding of targeting signaling pathways that influences malignant behavior of brain tumor cells might open the way for the development of novel targeted therapies. Thus, there is an urgent need for a more comprehensive understanding of the pathogenesis of these brain tumors, which might result in greater progress in therapeutic approaches. This paper began with a brief description of the epidemiology, incidence, risk factors, as well as survival of brain tumors. Next, the major signaling pathways underlying these brain tumors' pathogenesis and current progress in therapies, including clinical trials, targeted therapies, immunotherapies, and system therapies, have been systemically reviewed and discussed. Finally, future perspective and challenges of development of novel therapeutic strategies in brain tumor were emphasized.

GANT61 suppresses cell survival, invasion and epithelial-mesenchymal transition through inactivating AKT/mTOR and JAK/STAT3 pathways in anaplastic thyroid carcinoma

Glioma-associated oncogene (Gli) antagonist-61 (GANT61) not only suppresses the malignant behavior of several cancers but also presents synergistic effects with other anticancer agents on suppressing the progression of cancers, while relevant information is rare in anaplastic thyroid carcinoma (ATC). This study aimed to explore the therapeutic effect of GANT61 in ATC and its molecular mechanism. ATC cells (8505C and CAL-62) were treated with GANT61, followed by detection of cell proliferation, apoptosis, invasion and epithelial-mesenchymal transition (EMT) markers. Subsequently, RNA sequencing was performed to explore the potential downstream pathway. Following that, rescue experiments were conducted by SC79 (AKT activator) or colivelin (STAT3 activator) monotreatment or combined with GANT61 in ATC cells. GANT61 reduced Gli1 expression, suppressed proliferation at several time settings, promoted apoptosis, inhibited invasion and increased E-cadherin while decreased Vimentin and Snail expressions (EMT markers) in ATC cells. The subsequent RNA sequence identified 85 upregulated differentially expressed genes (DEGs) and 71 downregulated DEGs in GANT61-treated ATC cells, which were mainly enriched in PI3K/AKT, JAK/STAT, Hedgehog and mTOR pathways. Next, the inactivation of AKT/mTOR and JAK/STAT3 pathways by GANT61 treatment was verified by western blot. The following rescue experiments showed that SC79 or colivelin treatment promoted the malignant behaviors of ATC cells. More importantly, SC79 or colivelin treatment compensated the effect of GANT61 treatment on cell proliferation at several time settings and apoptosis, invasion, and part of that on EMT in ATC cells. GANT61 suppresses cell survival, invasion and EMT through inactivating AKT/mTOR or JAK/STAT3 pathways in ATC.

Non-coding RNAs and glioma: Focus on cancer stem cells

Glioblastoma and gliomas can have a wide range of histopathologic subtypes. These heterogeneous histologic phenotypes originate from tumor cells with the distinct functions of tumorigenesis and self-renewal, called glioma stem cells (GSCs). GSCs are characterized based on multi-layered epigenetic mechanisms, which control the expression of many genes. This epigenetic regulatory mechanism is often based on functional non-coding RNAs (ncRNAs). ncRNAs have become increasingly important in the pathogenesis of human cancer and work as oncogenes or tumor suppressors to regulate carcinogenesis and progression. These RNAs by being involved in chromatin remodeling and modification, transcriptional regulation, and alternative splicing of pre-mRNA, as well as mRNA stability and protein translation, play a key role in tumor development and progression. Numerous studies have been performed to try to understand the dysregulation pattern of these ncRNAs in tumors and cancer stem cells (CSCs), which show robust differentiation and self-regeneration capacity. This review provides recent findings on the role of ncRNAs in glioma development and progression, particularly their effects on CSCs, thus accelerating the clinical implementation of ncRNAs as promising tumor biomarkers and therapeutic targets.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Hedgehog signaling regulates the development and treatment of glioblastoma

Glioblastoma (GBM) is the most common and fatal malignant tumor type of the central nervous system. GBM affects public health and it is important to identify biomarkers to improve diagnosis, reduce drug resistance and improve prognosis (e.g., personalized targeted therapies). Hedgehog (HH) signaling has an important role in embryonic development, tissue regeneration and stem cell renewal. A large amount of evidence indicates that both normative and non-normative HH signals have an important role in GBM. The present study reviewed the role of the HH signaling pathway in the occurrence and progression of GBM. Furthermore, the effectiveness of drugs that target different components of the HH pathway was also examined. The HH pathway has an important role in reversing drug resistance after GBM conventional treatment. The present review highlighted the relevance of HH signaling in GBM and outlined that this pathway has a key role in the occurrence, development and treatment of GBM.

Canonical Hedgehog Pathway and Noncanonical GLI Transcription Factor Activation in Cancer

The Hedgehog signaling pathway is one of the fundamental pathways required for development and regulation of postnatal regeneration in a variety of tissues. The pathway has also been associated with cancers since the identification of a mutation in one of its components, PTCH, as the cause of Basal Cell Nevus Syndrome, which is associated with several cancers. Our understanding of the pathway in tumorigenesis has expanded greatly since that initial discovery over two decades ago. The pathway has tumor-suppressive and oncogenic functions depending on the context of the cancer. Furthermore, noncanonical activation of GLI transcription factors has been reported in a number of tumor types. Here, we review the roles of canonical Hedgehog signaling pathway and noncanonical GLI activation in cancers, particularly epithelial cancers, and discuss an emerging concept of the distinct outcomes that these modes have on cancer initiation and progression.

The scaffolding protein DLG5 promotes glioblastoma growth by controlling Sonic Hedgehog signaling in tumor stem cells

BACKGROUND

Tumor invasion, a hallmark of malignant gliomas, involves reorganization of cell polarity and changes in the expression and distribution of scaffolding proteins associated with polarity complexes. The scaffolding proteins of the DLG family are usually downregulated in invasive tumors and regarded as tumor suppressors. Despite their important role in regulating neurodevelopmental signaling, the expression and functions of DLG proteins have remained almost entirely unexplored in malignant gliomas.

METHODS

Western blot, immunohistochemistry, and analysis of gene expression were used to quantify DLG members in glioma specimens and cancer datasets. Over-expression and knockdown of DLG5, the highest-expressed DLG member in glioblastoma, were used to investigate its effects on tumor stem cells and tumor growth. qRT-PCR, Western blotting, and co-precipitation assays were used to investigate DLG5 signaling mechanisms.

RESULTS

DLG5 was upregulated in malignant gliomas compared to other solid tumors, being the predominant DLG member in all glioblastoma molecular subtypes. DLG5 promoted glioblastoma stem cell invasion, viability, and self-renewal. Knockdown of this protein in vivo disrupted tumor formation and extended survival. At the molecular level, DLG5 regulated Sonic Hedgehog (Shh) signaling, making DLG5-deficient cells insensitive to Shh ligand. Loss of DLG5 increased the proteasomal degradation of Gli1, underlying the loss of Shh signaling and tumor stem cell sensitization.

CONCLUSIONS

The high expression and pro-tumoral functions of DLG5 in glioblastoma, including its dominant regulation of Shh signaling in tumor stem cells, reveal a novel role for this protein that is strikingly different from its proposed tumor-suppressor role in other solid tumors.

PTCH1 mutant small cell glioblastoma in a patient with Gorlin syndrome: A case report

Gorlin syndrome or nevoid basal cell carcinoma syndrome is a rare genetic disease characterized by predisposition to congenital defects, basal cell carcinomas and medulloblastoma. The syndrome results from a heritable mutation in PATCHED1 (PTCH1), causing constitutive activation of the Hedgehog pathway. The present study described a patient with Gorlin syndrome who presented early in life with characteristic basal cell carcinomas and later developed a small cell glioblastoma (GBM), World Health Organization grade IV, associated with a Patched 1 (PTCH1) N97fs*43 mutation. Comprehensive genomic profiling of GBM tissues also revealed multiple co-occurring alterations including cyclin-dependent kinase 4 (CDK4) amplification, receptor tyrosine-protein kinase 3 (ERBB3) amplification, a fibroblast growth factor receptor 1 and transforming acidic coiled-coil containing protein 1 (FGFR1-TACC1) fusion, zinc finger protein (GLI1) amplification, E3 ubiquitin-protein ligase (MDM2) amplification and spectrin α chain, erythrocytic 1 (SPTA1) T1151fs*24. After the biopsy, imaging revealed extensive leptomeningeal enhancement intracranially and around the cervical spinal cord due to leptomeningeal disease. The patient underwent craniospinal radiation followed by 6 months of adjuvant temozolomide (150 mg/m²) with good response. She was then treated with vismodegib for 11 months, first combined with temozolomide and then with bevacizumab, until disease progression was noted on MRI, with no significant toxicities associated with the combination therapy. She received additional therapies but ultimately succumbed to the disease four months later. The current study presents the first documentation in the literature of a primary (non-radiation induced) glioblastoma secondary to Gorlin syndrome. Based on this clinical experience, vismodegib should be considered in combination with standard-of-care therapies for patients with known Gorlin syndrome-associated glioblastomas and sonic hedgehog pathway mutations.

Targeting AKT and CK2 represents a novel therapeutic strategy for SMO constitutive activation-driven medulloblastoma

AIMS

Sonic hedgehog subtype medulloblastoma is featured with overactivation of hedgehog pathway and can be targeted by SMO-specific inhibitors. However, the resistance is frequently developed leading to treatment failure of SMO inhibitors. W535L mutation of SMO (SMOW535L ) is thought to be an oncogenic driver for Sonic hedgehog subtype MB and confer resistance to SMO inhibitors. The regulation network of SMOW535L remains to be explored in comparison with wild-type SMO (SMOWT ).

METHODS

In this study, we profiled transcriptomes, methylomes, and interactomes of MB cells expression SMOWT or SMOW535L in the treatment of DMSO or SMO inhibitor, respectively.

RESULTS

Analysis of transcriptomic data indicated that SMO inhibitor disrupted processes of endocytosis and cilium organization in MB cells with SMOWT , which are necessary for SMO activation. In MB cells with SMOW535L , however, SMO inhibitor did not affect the two processes-related genes, implying resistance of SMOW535L toward SMO inhibitor. Moreover, we noticed that SMO inhibitor significantly inhibited metabolism-related pathways. Our metabolic analysis indicated that nicotinate and nicotinamide metabolism, glycerolipid metabolism, beta-alanine metabolism, and synthesis and degradation of ketone bodies might be involved in SMOW535L function maintenance. Interactomic analysis revealed casein kinase II (CK2) as an important SMO-associated protein. Finally, we linked CK2 and AKT together and found combination of inhibitors targeting CK2 and AKT showed synergetic effects to inhibit the growth of MB cells with SMO constitutive activation mutation.

CONCLUSIONS

Taken together, our work described SMO-related transcriptomes, metabolomes, and interactomes under different SMO status and treatment conditions, identifying CK2 and AKT as therapeutic targets for SHH-subtype MB cells with SMO inhibitor resistance.

Comparison of the prognostic effect of sarcopenia on atezolizumab plus bevacizumab and lenvatinib therapy in hepatocellular carcinoma patients

Background and Aim

Sarcopenia has received much attention as a poor prognostic factor in various fields, and has also been reported to worsen prognosis in patients with hepatocellular carcinoma (HCC) treated with sorafenib or lenvatinib (LEN). Atezolizumab/bevacizumab (ATZ/BEV) is recommended as first‐line drug therapy for unresectable‐HCC, but the effect of sarcopenia on patients treated with ATZ/BEV is unknown.

Methods

We enrolled 98 patients treated with ATZ/BEV or LEN. Computed tomography performed before the initiation of drug therapy was used to diagnose sarcopenia in accordance with the criteria proposed by the Japanese Society of Hepatology. Patients were divided into two groups based on the presence or absence of sarcopenia in each regimen, and patient characteristics, adverse events, and prognosis were compared.

Results

In ATZ/BEV therapy, 57.1% of patients had sarcopenia. The sarcopenia group had significantly more women (P = 0.0125) and more macroscopic vascular invasion (P = 0.0270). Sarcopenia had no significant effect on progression‐free survival (PFS) and overall survival (OS). In LEN therapy, 63.4% of patients had sarcopenia. The sarcopenia group was significantly older (P = 0.0064) and had a higher number of women (P = 0.0003), a higher neutrophil–lymphocyte ratio (P = 0.0222), worse albumin–bilirubin grade (P = 0.0087), and worse best response (P = 0.0255). PFS (P = 0.0091) and OS (P = 0.0006) were worse in the sarcopenia group. In multivariate analysis, age (P = 0.0362), lymphocyte–monocyte ratio (P = 0.0365), and sarcopenia (P = 0.0268) were independent prognostic factors for OS.

Conclusion

In ATZ/BEV therapy, sarcopenia does not determine prognosis, and therapeutic efficacy can be expected even in cases of sarcopenia.

Tracing the origins of glioblastoma by investigating the role of gliogenic and related neurogenic genes/signaling pathways in GBM development: a systematic review

Background

Glioblastoma is one of the most aggressive tumors. The etiology and the factors determining its onset are not yet entirely known. This study investigates the origins of GBM, and for this purpose, it focuses primarily on developmental gliogenic processes. It also focuses on the impact of the related neurogenic developmental processes in glioblastoma oncogenesis. It also addresses why glial cells are at more risk of tumor development compared to neurons.

Methods

Databases including PubMed, MEDLINE, and Google Scholar were searched for published articles without any date restrictions, involving glioblastoma, gliogenesis, neurogenesis, stemness, neural stem cells, gliogenic signaling and pathways, neurogenic signaling and pathways, and astrocytogenic genes.

Results

The origin of GBM is dependent on dysregulation in multiple genes and pathways that accumulatively converge the cells towards oncogenesis. There are multiple layers of steps in glioblastoma oncogenesis including the failure of cell fate-specific genes to keep the cells differentiated in their specific cell types such as p300, BMP, HOPX, and NRSF/REST. There are genes and signaling pathways that are involved in differentiation and also contribute to GBM such as FGFR3, JAK-STAT, and hey1. The genes that contribute to differentiation processes but also contribute to stemness in GBM include notch, Sox9, Sox4, c-myc gene overrides p300, and then GFAP, leading to upregulation of nestin, SHH, NF-κB, and others. GBM mutations pathologically impact the cell circuitry such as the interaction between Sox2 and JAK-STAT pathway, resulting in GBM development and progression.

Conclusion

Glioblastoma originates when the gene expression of key gliogenic genes and signaling pathways become dysregulated. This study identifies key gliogenic genes having the ability to control oncogenesis in glioblastoma cells, including p300, BMP, PAX6, HOPX, NRSF/REST, LIF, and TGF beta. It also identifies key neurogenic genes having the ability to control oncogenesis including PAX6, neurogenins including Ngn1, NeuroD1, NeuroD4, Numb, NKX6-1 Ebf, Myt1, and ASCL1. This study also postulates how aging contributes to the onset of glioblastoma by dysregulating the gene expression of NF-κB, REST/NRSF, ERK, AKT, EGFR, and others.

The importance of body composition assessment for patients with advanced hepatocellular carcinoma by bioelectrical impedance analysis in lenvatinib treatment

BACKGROUND AND AIMS

The aim of this study was to investigate the relationship between body composition before lenvatinib treatment and prognosis in patients with hepatocellular carcinoma (HCC). We also assessed the relationship between the rate of change in body composition after lenvatinib treatment and prognosis.

METHODS

Eighty-one patients with advanced HCC who were treated with lenvatinib were enrolled. We assessed prognosis, various clinical data, body composition parameters obtained by bioelectrical impedance analysis (BIA), and handgrip strength.

RESULTS

Multivariate analysis showed that an extracellular water to total body water ratio (ECW/TBW) ≤ 0.400 at treatment initiation was associated with longer overall survival (OS), progression-free survival (PFS), and post-progression survival (PPS) (OS: hazard ratio [H0R], 4.72; 95% CI, 12.03-11.00; P < 0.001; PFS: HR, 2.66; 95% CI, 1.33-5.34; P = 0.0057; PPS: HR, 3.08; 95% CI, 1.32-7.18; P = 0.0093). Multivariate analysis also showed that the skeletal muscle mass index (SMI) of the arm at treatment initiation was associated with a longer PFS (HR, 2.12; 95% CI, 1.23-3.64; P = 0.0069). In the group with an ECW/TBW ≤ 0.400 before lenvatinib treatment, univariate analysis showed that the rate of change in only the arm SMI was associated with a longer OS and PFS.

CONCLUSION

Body composition assessment by BIA before and after lenvatinib treatment is useful in predicting prognosis in lenvatinib-treated patients with HCC.

The multifaceted mechanisms of malignant glioblastoma progression and clinical implications

With the application of high throughput sequencing technologies at single-cell resolution, studies of the tumor microenvironment in glioblastoma, one of the most aggressive and invasive of all cancers, have revealed immense cellular and tissue heterogeneity. A unique extracellular scaffold system adapts to and supports progressive infiltration and migration of tumor cells, which is characterized by altered composition, effector delivery, and mechanical properties. The spatiotemporal interactions between malignant and immune cells generate an immunosuppressive microenvironment, contributing to the failure of effective anti-tumor immune attack. Among the heterogeneous tumor cell subpopulations of glioblastoma, glioma stem cells (GSCs), which exhibit tumorigenic properties and strong invasive capacity, are critical for tumor growth and are believed to contribute to therapeutic resistance and tumor recurrence. Here we discuss the role of extracellular matrix and immune cell populations, major components of the tumor ecosystem in glioblastoma, as well as signaling pathways that regulate GSC maintenance and invasion. We also highlight emerging advances in therapeutic targeting of these components.

Expression of activator proteins of SHH/GLI and PI3K/Akt/mTORC1 signaling pathways in human gliomas is associated with high grade tumors

Recent findings have demonstrated a synergic crosstalk between SHH/GLI and PI3K/Akt/mTORC1 signaling in glioblastoma progression cells in vitro and in tumors in mice, but it is not known if this also occurs in human gliomas. We then aimed to investigate the expression of key proteins of these pathways in different human gliomas. The expression of PTEN, phospho-Akt (Ser473), phospho-S6K1 (Thr389), SHH, GLI1, GLI2 and GLI3 was assessed by immunohistochemistry in gliomas and in control brain tissues. The pattern of expression of each protein was established according to glioma type, glioma grade and to cell type; the relative expression of each protein was used to perform statistical analyses. We found that the expression of proteins of both signaling pathways differs between normal brain and glioma tissues. For instance, normal astrocytes had a different protein expression pattern compared with reactive and tumoral astrocytes. Interestingly, we detected a recurrent pattern of expression of GLI3 in oligodendrocytes and of phospho-S6K1 in mitotic neoplastic cells. We also identified differences of cell signaling according to glioma type: oligodendrogliomas and ependymomas are related with the expression of SHH/GLI proteins. Finally, we detected that high grade gliomas statistically correlate with the expression of GLI1 and GLI2, and that GLI1, GLI2, phospho-Akt and phospho-S6K1 are more expressed in patients with less survival, suggesting that activation of these cell signaling influences glioma outcome and patient survival. In summary, our results show that proteins of PI3K/Akt/mTORC1 and SHH/GLI pathways are differentially expressed in human gliomas according to tumor type and grade, and suggest that the activation of these signaling networks is associated with glioma progression.

Glioblastoma Therapy: Rationale for a Mesenchymal Stem Cell-based Vehicle to Carry Recombinant Viruses

Evasion of growth suppression is among the prominent hallmarks of cancer. Phosphatase and tensin homolog (PTEN) and p53 tumor-suppressive pathways are compromised in most human cancers, including glioblastoma (GB). Hence, these signaling pathways are an ideal point of focus for novel cancer therapeutics. Recombinant viruses can selectivity kill cancer cells and carry therapeutic genes to tumors. Specifically, oncolytic viruses (OV) have been successfully employed for gene delivery in GB animal models and showed potential to neutralize immunosuppression at the tumor site. However, the associated systemic immunogenicity, inefficient transduction of GB cells, and inadequate distribution to metastatic tumors have been the major bottlenecks in clinical studies. Mesenchymal stem cells (MSCs), with tumor-tropic properties and immune privilege, can improve OVs targeting. Remarkably, combining the two approaches can address their individual issues. Herein, we summarize findings to advocate the reactivation of tumor suppressors p53 and PTEN in GB treatment and use MSCs as a "Trojan horse" to carry oncolytic viral cargo to disseminated tumor beds. The integration of MSCs and OVs can emerge as the new paradigm in cancer treatment.

A primary cilium in oligodendrocytes: a fine structure signal of repairs in thalamic Osmotic Demyelination Syndrome (ODS)

A murine osmotic demyelination syndrome (ODS) model of the central nervous system included the relay thalamic ventral posterolateral (VPL) and ventral posteromedial (VPM) nuclei. Morphologic comparisons between treatments have revealed oligodendrocyte changes and, already 12 hours following the osmolality restoration, some heavily contrasted oligodendrocytes formed a unique intracellular primary cilium. This unique structure, found in vivo, in mature CNS oligodendrocytes, could account for a local awakening of some of the developmental proteome as it can be expressed in oligodendrocyte precursor cells. This resilience accompanied the emergence of arl13b protein expression along with restoration of nerve cell body axon hillocks shown in a previous issue of this journal. Additionally, the return of several thalamic oligodendrocyte fine features (nucleus, organelles) was shown 36 h later, including some mitosis. Those cell restorations and recognized translational activities comforted that local repairs could again take place, due to oligodendrocyte resilience after ODS instead or added to a postulated immigration of oligodendrocyte precursor cells distant from the sites of myelinolysis.

Small Molecules of Marine Origin as Potential Anti-Glioma Agents

Marine organisms are able to produce a plethora of small molecules with novel chemical structures and potent biological properties, being a fertile source for discovery of pharmacologically active compounds, already with several marine-derived agents approved as drugs. Glioma is classified by the WHO as the most common and aggressive form of tumor on CNS. Currently, Temozolomide is the only chemotherapeutic option approved by the FDA even though having some limitations. This review presents, for the first time, a comprehensive overview of marine compounds described as anti-glioma agents in the last decade. Nearly fifty compounds were compiled in this document and organized accordingly to their marine sources. Highlights on the mechanism of action and ADME properties were included. Some of these marine compounds could be promising leads for the discovery of new therapeutic alternatives for glioma treatment.

The Role of Neurodevelopmental Pathways in Brain Tumors

Disruptions to developmental cell signaling pathways and transcriptional cascades have been implicated in tumor initiation, maintenance and progression. Resurgence of aberrant neurodevelopmental programs in the context of brain tumors highlights the numerous parallels that exist between developmental and oncologic mechanisms. A deeper understanding of how dysregulated developmental factors contribute to brain tumor oncogenesis and disease progression will help to identify potential therapeutic targets for these malignancies. In this review, we summarize the current literature concerning developmental signaling cascades and neurodevelopmentally-regulated transcriptional programs. We also examine their respective contributions towards tumor initiation, maintenance, and progression in both pediatric and adult brain tumors and highlight relevant differentiation therapies and putative candidates for prospective treatments.

A novel protein encoded by circular SMO RNA is essential for Hedgehog signaling activation and glioblastoma tumorigenicity

BACKGROUND

Aberrant activation of the Hedgehog pathway drives tumorigenesis of many cancers, including glioblastoma. However, the sensitization mechanism of the G protein-coupled-like receptor smoothened (SMO), a key component of Hedgehog signaling, remains largely unknown.

RESULTS

In this study, we describe a novel protein SMO-193a.a. that is essential for Hedgehog signaling activation in glioblastoma. Encoded by circular SMO (circ-SMO), SMO-193a.a. is required for sonic hedgehog (Shh) induced SMO activation, via interacting with SMO, enhancing SMO cholesterol modification, and releasing SMO from the inhibition of patched transmembrane receptors. Deprivation of SMO-193a.a. in brain cancer stem cells attenuates Hedgehog signaling intensity and suppresses self-renewal, proliferation in vitro, and tumorigenicity in vivo. Moreover, circ-SMO/SMO-193a.a. is positively regulated by FUS, a direct transcriptional target of Gli1. Shh/Gli1/FUS/SMO-193a.a. form a positive feedback loop to sustain Hedgehog signaling activation in glioblastoma. Clinically, SMO-193a.a. is more specifically expressed in glioblastoma than SMO and is relevant to Gli1 expression. Higher expression of SMO-193a.a. predicts worse overall survival of glioblastoma patients, indicating its prognostic value.

CONCLUSIONS

Our study reveals that SMO-193a.a., a novel protein encoded by circular SMO, is critical for Hedgehog signaling, drives glioblastoma tumorigenesis and is a novel target for glioblastoma treatment.

TSPAN7 Exerts Anti-Tumor Effects in Bladder Cancer Through the PTEN/PI3K/AKT Pathway

The tetraspanin protein superfamily participate in the dynamic regulation of cellular membrane compartments expressed in a variety of tumor types, which may alter the biological properties of cancer cells such as cell development, activation, growth and motility. The role of tetraspanin 7 (TSPAN7) has never been investigated in bladder cancer (BCa). In this study, we aimed to investigate the biological function of TSPAN7 and its therapeutic potential in human BCa. First, via reverse transcription and quantitative real-time PCR (qRT-PCR), we observed downregulation of TSPAN7 in BCa tissues samples and cell lines and found that this downregulation was associated with a relatively high tumor stage and tumor grade. Low expression of TSPAN7 was significantly correlated with a much poorer prognosis for BCa patients than was high expression. Immunohistochemistry (IHC) showed that low TSPAN7 expression was a high-risk predictor of BCa patient overall survival. Furthermore, the inhibitory effects of TSPAN7 on the proliferation and migration of BCa cell lines were detected by CCK-8, wound-healing, colony formation and transwell assays in vitro. Flow cytometry analysis revealed that TSPAN7 induced BCa cell lines apoptosis and cell cycle arrest. In vivo, tumor growth in nude mice bearing tumor xenografts could be obviously affected by overexpression of TSPAN7. Western blotting showed that overexpression of TSPAN7 activated Bax, cleaved caspase-3 and PTEN but inactivated Bcl-2, p-PI3K, and p-AKT to inhibit BCa cell growth via the PTEN/PI3K/AKT pathway. Taken together, our study will help identify a potential marker for BCa diagnosis and supply a target molecule for BCa treatment.

Systematic review and meta-analysis of the prognostic significance of microRNAs related to metastatic and EMT process among prostate cancer patients

The ability of tumor cells to spread from their origin place and form secondary tumor foci is determined by the epithelial-mesenchymal transition process. In epithelial tumors such as prostate cancer (PCa), the loss of intercellular interactions can be observed as a change in expression of polarity proteins. Epithelial cells acquire ability to migrate, what leads to the formation of distal metastases. In recent years, the interest in miRNA molecules as potential future treatment options has increased. In tumor microenvironment, miRNAs have the ability to regulate signal transduction pathways, where they can act as suppressors or oncogenes. MiRNAs are secreted by cancer cells, and the changes in their expression levels are closely related to a cancer progression, including epithelial-mesenchymal transition. These molecules offer new diagnostic and therapeutic possibilities. Therapeutics which make use of synthesized RNA fragments and mimic or block miRNAs affected in PCa, may lead to inhibition of tumor progression and even disease re-emission. Based on appropriate qualification criteria, we conducted a selection process to identify scientific articles describing miRNAs and their relation to epithelial-mesenchymal transition in PCa patients. The studies were published in English on Pubmed, Scopus and the Web of Science before August 08, 2019. Hazard ratios (HRs) and 95% confidence intervals (CI) as well as total Gleason score were used to assess the concordance between miRNAs and presence of metastases. A total of 13 studies were included in our meta-analysis, representing 1608 PCa patients and 15 miRNA molecules. Our study clarifies a relationship between the clinicopathological features of PCa and the aberrant expression of several miRNA as well as the complex mechanism of miRNA molecules involvement in the induction and promotion of the metastatic mechanism in PCa.

Targeting the GLI family of transcription factors for the development of anti-cancer drugs

INTRODUCTION

GLI1 is a transcription factor that has been identified as a downstream effector for multiple tumorigenic signaling pathways. These include the Hedgehog, RAS-RAF-MEK-ERK, and PI3K-AKT-mTOR pathways, which have all been separately validated as individual anti-cancer drug targets. The identification of GLI1 as a key transcriptional regulator for each of these pathways highlights its promise as a therapeutic target. Small molecule GLI1 inhibitors are potentially efficacious against human malignancies arising from multiple oncogenic mechanisms.

AREAS COVERED

This review provides an overview of the key oncogenic cellular pathways that regulate GLI1 transcriptional activity. It also provides a detailed account of small molecule GLI1 inhibitors that are currently under development as potential anti-cancer chemotherapeutics.

EXPERT OPINION

Interest in developing inhibitors of GLI1-mediated transcription has significantly increased as its role in multiple oncogenic signaling pathways has been elucidated. To date, it has proven difficult to directly target GLI1 with small molecules, and the majority of compounds that inhibit GLI1 activity function through indirect mechanisms. To date, no direct-acting GLI1 inhibitor has entered clinical trials. The identification and development of new scaffolds that can bind and directly inhibit GLI1 are essential to further advance this class of chemotherapeutics.

TFII-I-mediated polymerase pausing antagonizes GLI2 induction by TGFβ

The modulation of GLI2, an oncogenic transcription factor commonly upregulated in cancer, is in many cases not due to genetic defects, suggesting dysregulation through alternative mechanisms. The identity of these molecular events remains for the most part unknown. Here, we identified TFII-I as a novel repressor of GLI2 expression. Mapping experiments suggest that the INR region of the GLI2 promoter is necessary for GLI2 repression. ChIP studies showed that TFII-I binds to this INR. TFII-I knockdown decreased the binding of NELF-A, a component of the promoter–proximal pausing complex at this site, and enriched phosphorylated RNAPII serine 2 in the GLI2 gene body. Immunoprecipitation studies demonstrate TFII-I interaction with SPT5, another pausing complex component. TFII-I overexpression antagonized GLI2 induction by TGFβ, a known activator of GLI2 in cancer cells. TGFβ reduced endogenous TFII-I binding to the INR and increased RNAPII SerP2 in the gene body. We demonstrate that this regulatory mechanism is not exclusive of GLI2. TGFβ-induced genes CCR7, TGFβ1 and EGR3 showed similar decreased TFII-I and NELF-A INR binding and increased RNAPII SerP2 in the gene body post-TGFβ treatment. Together these results identify TFII-I as a novel repressor of a subset of TGFβ-responsive genes through the regulation of RNAPII pausing.

Exploiting the Complexities of Glioblastoma Stem Cells: Insights for Cancer Initiation and Therapeutic Targeting

The discovery of glioblastoma stem cells (GSCs) in the 2000s revolutionized the cancer research field, raising new questions regarding the putative cell(s) of origin of this tumor type, and partly explaining the highly heterogeneous nature of glioblastoma (GBM). Increasing evidence has suggested that GSCs play critical roles in tumor initiation, progression, and resistance to conventional therapies. The remarkable oncogenic features of GSCs have generated significant interest in better defining and characterizing these cells and determining novel pathways driving GBM that could constitute attractive key therapeutic targets. While exciting breakthroughs have been achieved in the field, the characterization of GSCs is a challenge and the cell of origin of GBM remains controversial. For example, the use of several cell-surface molecular markers to identify and isolate GSCs has been a challenge. It is now widely accepted that none of these markers is, per se, sufficiently robust to distinguish GSCs from normal stem cells. Finding new strategies that are able to more efficiently and specifically target these niches could also prove invaluable against this devastating and therapy-insensitive tumor. In this review paper, we summarize the most relevant findings and discuss emerging concepts and open questions in the field of GSCs, some of which are, to some extent, pertinent to other cancer stem cells.

Knockdown of DEPDC1B inhibits the development of glioblastoma

Background

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with a poor prognosis. DEPDC1B (DEP domain-containing protein 1B) has been shown to be associated with some types of malignancies. However, the role and underlying regulatory mechanisms of DEPDC1B in GBM remain elusive.

Methods

In this research, the expression level of DEPDC1B in GBM tissues was detected by IHC. The DEPDC1B knockdown cell line was constructed, identified by qRT-PCR and western blot and used to construct the xenotransplantation mice model and intracranial xenograft model. MTT assay, colony formation assay, flow cytometry, and Transwell assay were used to detected cell proliferation, apoptosis and migration.

Results

The results proved that DEPDC1B was significantly upregulated in tumor tissues, and silencing DEPDC1B could inhibit proliferation, migration and promote apoptosis of GBM cell. In addition, human apoptosis antibody array detection showed that after DEPDC1B knockdown, the expression of apoptosis-related proteins was downregulated, such as IGFBP-2, Survivin, N-cadherin, Vimentin and Snail. Finally, we indicated that knockdown of DEPDC1B significantly inhibited tumor growth in vivo.

Conclusions

In summary, DEPDC1B was involved in the development and progression of GBM, which may be a potential therapeutic target and bring a breakthrough in the treatment.

N2M2 (NOA-20) phase I/II trial of molecularly matched targeted therapies plus radiotherapy in patients with newly diagnosed non-MGMT hypermethylated glioblastoma

Background

Patients with glioblastoma without O6-methylguanine-DNA methyltransferase (MGMT) promoter hypermethylation are unlikely to benefit from alkylating chemotherapy with temozolomide (TMZ). Trials aiming at replacing TMZ with targeted agents in unselected patient populations have failed to demonstrate any improvement of survival. Advances in molecular understanding and diagnostic precision enable identification of key genetic alterations in a timely manner and in principle allow treatments with targeted compounds based on molecular markers.

Methods

The NCT Neuro Master Match (N2M2) trial is an open-label, multicenter, phase I/IIa umbrella trial for patients with newly diagnosed isocitrate dehydrogenase (IDH) wildtype glioblastoma without MGMT promoter hypermethylation to show safety, feasibility, and preliminary efficacy of treatment with targeted compounds in addition to standard radiotherapy based on molecular characterization. N2M2 is formally divided into a Discovery and a Treatment part. Discovery includes broad molecular neuropathological diagnostics to detect predefined biomarkers for targeted treatments. Molecular diagnostics and bioinformatic evaluation are performed within 4 weeks, allowing a timely initiation of postoperative treatment. Stratification for Treatment takes place in 5 subtrials, including alectinib, idasanutlin, palbociclib, vismodegib, and temsirolimus as targeted therapies, according to the best matching molecular alteration. Patients without matching alterations are randomized between subtrials without strong biomarkers using atezolizumab and asinercept (APG101) and the standard of care, TMZ. For the phase I parts, a Bayesian criterion is used for continuous monitoring of toxicity. In the phase II trials, progression-free survival at 6 months is used as endpoint for efficacy.

Results

Molecular diagnostics and bioinformatic evaluation are performed within 4 weeks, allowing a timely initiation of postoperative treatment. Stratification for Treatment takes place in 5 subtrials, including alectinib, idasanutlin, palbociclib, vismodegib, and temsirolimus as targeted therapies, according to the best matching molecular alteration. Patients without matching alterations are randomized between subtrials without strong biomarkers using atezolizumab and asinercept (APG101) and the standard of care, TMZ. For the phase I parts, a Bayesian criterion is used for continuous monitoring of toxicity. In the phase II trials, progression-free survival at 6 months is used as endpoint for efficacy.

Discussion

Molecularly informed trials may provide the basis for the development of predictive biomarkers and help to understand and select patient subgroups who will benefit.

Skeletal Muscle Loss during Tyrosine Kinase Inhibitor Treatment for Advanced Hepatocellular Carcinoma Patients

INTRODUCTION

The measurement of body composition such as the skeletal muscle index (SMI) has been reported to be useful for predicting prognosis in hepatocellular carcinoma (HCC). In this study, we analyzed skeletal muscle change during sorafenib and lenvatinib therapy and the association between SMI and prognosis.

METHODS

A total of 67 patients with advanced HCC and Child-Pugh grade A status treated with tyrosine kinase inhibitors (TKIs) at Hiroshima University between September 2009 and December 2018 were enrolled in this retrospective cohort study. Patients underwent computed tomography (CT) imaging before starting sorafenib treatment and 1-3 months after treatment initiation.

RESULTS

In all patients, the median SMI was 45.3 cm²/m² before TKI treatment and 42.1 cm²/m² after treatment; 54 of 67 (80.6%) patients experienced SMI loss. The median ΔSMI was -1.5 cm²/m²/months, and no difference in ΔSMI was observed between patients receiving sorafenib and lenvatinib. No significant differences were observed in median ΔSMI between patients with and without progressive disease (-2.35 and -1.1 cm²/m²/months, respectively), albumin-bilirubin grade 1 and 2 group disease (-1.7 and -1.5 cm²/m²/months, respectively), and relative dose intensity ≤80 and >80 (-1.8 and -1.2 cm²/m²/months, respectively).

CONCLUSION

This report demonstrated that patients receiving TKI treatment experienced a significant loss of skeletal muscle mass regardless of disease progression, hepatic reserve, or which TKI (sorafenib or lenvatinib) they received.

Implementing Patient-Derived Xenografts to Assess the Effectiveness of Cyclin-Dependent Kinase Inhibitors in Glioblastoma

Glioblastoma (GBM) is the most common primary brain tumor with no available cure. As previously described, seliciclib, a first-generation cyclin-dependent kinase (CDK) inhibitor, down-regulates the anti-apoptotic protein, Mcl-1, in GBM, thereby sensitizing GBM cells to the apoptosis-inducing effects of the death receptor ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we have assessed the efficacy of seliciclib when delivered in combination with the antibody against human death receptor 5, drozitumab, in clinically relevant patient-derived xenograft (PDX) models of GBM. A reduction in viability and significant levels of apoptosis were observed in vitro in human GBM neurospheres following treatment with seliciclib plus drozitumab. While the co-treatment strategy induced a similar effect in PDX models, the dosing regimen required to observe seliciclib-targeted responses in the brain, resulted in lethal toxicity in 45% of animals. Additional studies showed that the second-generation CDK inhibitor, CYC065, with improved potency in comparison to seliciclib, induced a significant decrease in the size of human GBM neurospheres in vitro and was well tolerated in vivo, upon administration at clinically relevant doses. This study highlights the continued need for robust pre-clinical assessment of promising treatment approaches using clinically relevant models.

Mutations in the sonic hedgehog pathway cause macrocephaly-associated conditions due to crosstalk to the PI3K/AKT/mTOR pathway

The hedgehog (Hh) pathway is highly conserved and required for embryonic patterning and determination. Mutations in the Hh pathway are observed in sporadic tumors as well as under syndromic conditions. Common to these syndromes are the findings of polydactyly/syndactyly and brain overgrowth. The latter is also a finding most commonly observed in the cases of mutations in the PI3K/AKT/mTOR pathway. We have identified novel Hh pathway mutations and structural copy number variations in individuals with somatic overgrowth, macrocephaly, dysmorphic facial features, and developmental delay, which phenotypically closely resemble patients with phosphatase and tensin homolog (PTEN) mutations. We hypothesized that brain overgrowth and phenotypic overlap with syndromic overgrowth syndromes in these cases may be due to crosstalk between the Hh and PI3K/AKT/mTOR pathways. To test this, we modeled disease-associated variants by generating PTCH1 and Suppressor of Fused (SUFU) heterozygote cell lines using the CRISPR/Cas9 system. These cells demonstrate activation of PI3K signaling and increased phosphorylation of its downstream target p4EBP1 as well as a distinct cellular phenotype. To further investigate the mechanism underlying this crosstalk, we treated human neural stem cells with sonic hedgehog (SHH) ligand and performed transcriptional analysis of components of the mTOR pathway. These studies identified decreased expression of a set of mTOR negative regulators, leading to its activation. We conclude that there is a significant crosstalk between the SHH and PI3K/AKT/mTOR. We propose that this crosstalk is responsible for why mutations in PTCH1 and SUFU lead to macrocephaly phenotypes similar to those observed in PTEN hamartoma and other overgrowth syndromes associated with mutations in PI3K/AKT/mTOR pathway genes.

Low mutational load in pediatric medulloblastoma still translates into neoantigens as targets for specific T-cell immunotherapy

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in childhood and adolescence. Although some patients present with distinct genetic alterations, such as mutated TP53 or MYC amplification, pediatric medulloblastoma is a tumor entity with minimal mutational load and low immunogenicity.

METHODS

We identified tumor-specific mutations using next-generation sequencing of medulloblastoma DNA and RNA derived from primary tumor samples from pediatric patients. Tumor-specific mutations were confirmed using deep sequencing and in silico analyses predicted high binding affinity of the neoantigen-derived peptides to the patients' human leukocyte antigen molecules. Tumor-specific peptides were synthesized and used to induce a de novo T-cell response characterized by interferon gamma and tumor necrosis factor alpha release of CD8⁺ cytotoxic T cells in vitro.

RESULTS

Despite low mutational tumor burden, at least two immunogenic tumor-specific peptides were identified in each patient. T cells showed a balanced CD4/CD8 ratio and mostly effector memory phenotype. Induction of a CD8-specific T-cell response was achieved for the neoepitopes derived from Histidine Ammonia-Lyase (HAL), Neuraminidase 2 (NEU2), Proprotein Convertase Subtilisin (PCSK9), Programmed Cell Death 10 (PDCD10), Supervillin (SVIL) and tRNA Splicing Endonuclease Subunit 54 (TSEN54) variants.

CONCLUSION

Detection of patient-specific, tumor-derived neoantigens confirms that even in tumors with low mutational load a molecular design of targets for specific T-cell immunotherapy is possible. The identified neoantigens may guide future approaches of adoptive T-cell transfer, transgenic T-cell receptor transfer or tumor vaccination.

Non-canonical Hedgehog Signaling Pathway in Cancer: Activation of GLI Transcription Factors Beyond Smoothened

The Hedgehog-GLI (HH-GLI) pathway is a highly conserved signaling that plays a critical role in controlling cell specification, cell–cell interaction and tissue patterning during embryonic development. Canonical activation of HH-GLI signaling occurs through binding of HH ligands to the twelve-pass transmembrane receptor Patched 1 (PTCH1), which derepresses the seven-pass transmembrane G protein-coupled receptor Smoothened (SMO). Thus, active SMO initiates a complex intracellular cascade that leads to the activation of the three GLI transcription factors, the final effectors of the HH-GLI pathway. Aberrant activation of this signaling has been implicated in a wide variety of tumors, such as those of the brain, skin, breast, gastrointestinal, lung, pancreas, prostate and ovary. In several of these cases, activation of HH-GLI signaling is mediated by overproduction of HH ligands (e.g., prostate cancer), loss-of-function mutations in PTCH1 or gain-of-function mutations in SMO, which occur in the majority of basal cell carcinoma (BCC), SHH-subtype medulloblastoma and rhabdomyosarcoma. Besides the classical canonical ligand-PTCH1-SMO route, mounting evidence points toward additional, non-canonical ways of GLI activation in cancer. By non-canonical we refer to all those mechanisms of activation of the GLI transcription factors occurring independently of SMO. Often, in a given cancer type canonical and non-canonical activation of HH-GLI signaling co-exist, and in some cancer types, more than one mechanism of non-canonical activation may occur. Tumors harboring non-canonical HH-GLI signaling are less sensitive to SMO inhibition, posing a threat for therapeutic efficacy of these antagonists. Here we will review the most recent findings on the involvement of alternative signaling pathways in inducing GLI activity in cancer and stem cells. We will also discuss the rationale of targeting these oncogenic pathways in combination with HH-GLI inhibitors as a promising anti-cancer therapies.

Hedgehog pathway and smoothened inhibitors in cancer therapies

The hedgehog (Hh) pathway plays an important role in cancer development and maintenance, as ~25% of all cancers have aberrant Hh pathway activation. Targeted therapy for inhibition of the Hh pathway was thought to be promising for achieving clinical response in the Hh-dependent cancers. However, the results of new clinical trials with smoothened (SMO) antagonists do not show much success in cancers other than basal cell carcinoma. The studies suggest that the Hh pathway involves multiple mechanisms of activation or inhibition in primary cilia and interactions between several related pathways in different types of cells, which makes this pathway extremely complex. The SMO-specific antagonists may not stop all relevant pathways that may lead to escape or development of resistance. Therefore, in the Hh-dependent cancers, the inhibition of two or more oncogenic pathways (including the Hh pathway) with use of a single agent of a suitable multitarget profile or a combination of drugs seems promising for achieving clinical response in patients and decrease in resistance development with prolonged use of the specific SMO antagonists. Furthermore, for studying the effect of new treatments, the inclusion criteria should be more specific for selection of patients with aberrant Hh pathway activity confirmed by tests. These considerations will be very helpful for choosing the right patients and the right drugs for the best therapeutic outcome.

Hedgehog signaling inhibitors in solid and hematological cancers

BACKGROUND

The hedgehog signaling pathway is normally tightly regulated. Mutations in hedgehog pathway components may lead to abnormal activation. Aberrantly activated hedgehog signaling plays a major role in the development of solid and hematological cancer. In recent years, inhibitors have been developed that attenuate hedgehog signaling; 2 have been approved for use in basal cell carcinoma (BCC), while others are under development or in clinical trials. The aim of this review is to provide an overview of known hedgehog inhibitors (HHIs) and their potential for the treatment of hematological cancers and solid tumors beyond BCC.

DESIGN

Published literature was searched to identify articles relating to HHIs in noncutaneous cancer. Both preclinical and clinical research articles were included. In addition, relevant clinical trial results were identified from www.clinicaltrials.gov. Information on the pharmacology of HHIs is also included.

RESULTS

HHIs show activity in a variety of solid and hematological cancers. In preclinical studies, HHIs demonstrated efficacy in pancreatic cancer, rhabdomyosarcoma, breast cancer, and acute myeloid leukemia (AML). In clinical studies, HHIs showed activity in medulloblastoma, as well as prostate, pancreatic, and hematological cancers. Current clinical trials testing the efficacy of HHIs are underway for prostate, pancreatic, and breast cancers, as well as multiple myeloma and AML.

CONCLUSIONS

As clinical trial results become available, it will be possible to discern which additional tumor types are suited to HHI mono- or combination therapy with other anticancer agents. The latter strategy may be useful for delaying or overcoming drug resistance.

Role of Protein Kinases in Hedgehog Pathway Control and Implications for Cancer Therapy

Hedgehog (HH) signaling is an evolutionarily conserved pathway that is crucial for growth and tissue patterning during embryonic development. It is mostly quiescent in the adult, where it regulates tissue homeostasis and stem cell behavior. Aberrant reactivation of HH signaling has been associated to several types of cancer, including those in the skin, brain, prostate, breast and hematological malignancies. Activation of the canonical HH signaling is triggered by binding of HH ligand to the twelve-transmembrane protein PATCHED. The binding releases the inhibition of the seven-transmembrane protein SMOOTHENED (SMO), leading to its phosphorylation and activation. Hence, SMO activates the transcriptional effectors of the HH signaling, that belong to the GLI family of transcription factors, acting through a not completely elucidated intracellular signaling cascade. Work from the last few years has shown that protein kinases phosphorylate several core components of the HH signaling, including SMO and the three GLI proteins, acting as powerful regulatory mechanisms to fine tune HH signaling activities. In this review, we will focus on the mechanistic influence of protein kinases on HH signaling transduction. We will also discuss the functional consequences of this regulation and the possible implications for cancer therapy.

Down-regulation of miR-543 expression increases the sensitivity of colorectal cancer cells to 5-Fluorouracil through the PTEN/PI3K/AKT pathway

Resistance to chemotherapy is one of main obstacles in the treatment of colorectal cancer (CRC). However, the mechanisms are still unclear, and the treatment options are still limited. miR-543 has been indicated to act as an oncogene in some cancers, but its function in regulating chemoresistance has not been considered in CRC cells. This study investigated whether the down-regulation of miR-543 expression enhanced 5-fluorouracil (5-FU)-induced apoptosis in HCT8/FU colon cancer cells. In our study, qRT-PCR revealed that miR-543 expression was up-regulated in the HCT8/FU colon cancer cell line compared with that of HCT8 colon cancer cell line. An miR-543 inhibitor or mimic was transfected, followed by MTT assay to detect 5-FU sensitivity in HCT8 and HCT8/FU cell lines, which showed that IC₅₀ of 5-FU was positively correlated with miR-543 expression. Further studies showed that miR-543 enhanced drug resistance by down-regulating the expression of phosphatase and tensin homolog (PTEN), which negatively regulates protein kinase B (AKT) activation. Additionally, an elevated expression of PTEN reversed the chemoresistance of miR-543-overexpressing HCT8 cells to 5-FU. These results indicate that miR-543 might be a target to increase the sensitivity of CRC cells to 5-FU through the PTEN/PI3K/AKT pathway.