Hedgehog signaling: modulation of cancer properies and tumor mircroenvironment

Dysregulated transcriptional networks in KMT2A- and MLLT10-rearranged T-ALL

For children and young adults with T-lineage acute lymphoblastic leukemia (T-ALL), event free survival following relapse is < 10%. We recently showed that rearrangements of the mixed lineage leukemia gene (KMT2A-R) are associated with induction failure and an inferior survival in T-ALL. Because there are currently no molecular features that inform treatment strategies in T-ALL, we hypothesized that transcriptional alterations related to KMT2A-R and MLLT10-R T-ALL could identify biologically relevant genes and signaling pathways for the development of targeted therapies for these groups of patients. We analyzed microarray data from a retrospective cohort of 100 T-ALL patients to identify novel targets for KMT2A (n = 12) or MLLT10 (n = 9) chimeras. We identified 330 probe sets that could discriminate between these groups, including novel targets, like RUNX2, TCF4 or MYO6. The results were further validated in two independent data sets and the functional networks were analyzed to identify pathways that may be of pathogenic or therapeutic relevance.

The targeted regulation of Gli1 by miR-361 to inhibit epithelia-mesenchymal transition and invasion of esophageal carcinoma cells

Epithelia-mesenchymal transition (EMT) is critical for invasion and metastasis of esophageal carcinoma. Gli1, a transcriptional factor in Hedgehog pathway, is correlated with EMT, invasion and metastasis of tumors. However, its role in esophageal cancer is still unknown. Bioinformatics analysis revealed relationship between microRNA (miR)-361 and 3'-UTR of Gli1 gene. This study thus investigated the role of miR-361 and Gli1 in invasion and metastasis of esophageal cancer. Both tumor and adjacent tissues were collected from 58 esophageal cancer patients to test the expressions of miR-361 and Gli1, the relationship of which was confirmed by dual-luciferase reporter gene assay. Cultured esophageal cancer cells EC9706 were transfected with mimic NC, miR-361 mimic, si-NC, si-Gli1, miR-361 mimics+si-Glil, pQC or pQC-FU-Gli1. Transwell and colony formation assays were performed for cell invasion and attachment-independent growth. Expressions of Gli1, Snail, E-cadherin and N-cadherin proteins were revealed by Western blotting. The expression of Gli1 was significantly elevated in esophageal cancer tissues, along with lower miR-361 expression which was correlated with TNM stage. MiR-361 inhibited the expression of Gli1 via targeting on 3'-UTR of Gli1 gene. The transfection of miR-361 mimics and/or si-Gli1 significantly suppressed the growth of malignant cells. The over-expression of miR-361 and/or silencing of Gli1 decreased intracellular expression of Gli1, Snail and N-cadherin, and increased E-cadherin expression to suppress EMT and invasion of tumor cells while the opposite effects were obtained by over-expression of Gli1. Abnormal elevation of Gli1 and decrease of miR-361 were found in esophageal cancer tissues. MiR-361 weakened invasion of cancer cells and impeded EMT process via the inhibition of Gli1.

Targeting the Multidrug Transporter Ptch1 Potentiates Chemotherapy Efficiency

One of the crucial challenges in the clinical management of cancer is resistance to chemotherapeutics. Multidrug resistance (MDR) has been intensively studied, and one of the most prominent mechanisms underlying MDR is overexpression of adenosine triphosphate (ATP)-binding cassette (ABC) transporters. Despite research efforts to develop compounds that inhibit the efflux activity of ABC transporters and thereby increase classical chemotherapy efficacy, to date, the Food and Drug Administration (FDA) has not approved the use of any ABC transporter inhibitors due to toxicity issues. Hedgehog signaling is aberrantly activated in many cancers, and has been shown to be involved in chemotherapy resistance. Recent studies showed that the Hedgehog receptor Ptch1, which is over-expressed in many recurrent and metastatic cancers, is a multidrug transporter and it contributes to the efflux of chemotherapeutic agents such as doxorubicin, and to chemotherapy resistance. Remarkably, Ptch1 uses the proton motive force to efflux drugs, in contrast to ABC transporters, which use ATP hydrolysis. Indeed, the “reversed pH gradient” that characterizes cancer cells, allows Ptch1 to function as an efflux pump specifically in cancer cells. This makes Ptch1 a particularly attractive therapeutic target for cancers expressing Ptch1, such as lung, breast, prostate, ovary, colon, brain, adrenocortical carcinoma, and melanoma. Screening of chemical libraries have identified several molecules that are able to enhance the cytotoxic effect of different chemotherapeutic agents by inhibiting Ptch1 drug efflux activity in different cancer cell lines that endogenously over-express Ptch1. In vivo proof of concept has been performed in mice where combining one of these compounds with doxorubicin prevented the development of xenografted adrenocortical carcinoma tumors more efficiently than doxorubicin alone, and without obvious undesirable side effects. Therefore, the use of a Ptch1 drug efflux inhibitor in combination with classical or targeted therapy could be a promising therapeutic option for Ptch1-expressing cancers.

Stroma - A Double-Edged Sword in Pancreatic Cancer: A Lesson From Targeting Stroma in Pancreatic Cancer With Hedgehog Signaling Inhibitors

Pancreatic cancer is a uniformly lethal malignancy with an abundant dense desmoplastic stroma. Because of its dense stroma, conventional drugs were considered to not penetrate this physical barrier, and this caused a systemic drug resistance. Thus, abolishing this barrier with targeted agents is considered to improve the efficiency of chemotherapeutic treatment. The Hedgehog (Hh) signaling pathway is a critical regulator of pancreas development and plays diversified roles in pancreatic cancer stroma and neoplastic cells. Increasing Hh expression in neoplastic cells added desmoplastic stroma accumulation in orthotopic tumors, and Hh inhibitors that target the stroma have an ability to prolong the overall survival of Pdx-1-Cre/KrasG12D/p53R172H mice models via deleting the stromal components and increasing vascularity in pancreatic tumor. However, the failure of translation from bench to bedside indicate the complexity of the relationship between Hh signaling and desmoplastic stroma, and more insights into the complex relationships between Hh signaling pathway and stroma, even tumor cells, might help redesign Hh-targeted therapy. In this review, we discuss the possible mechanism of translation of Hh inhibitor in the clinic from pathology to molecular mechanism.

Role and inhibition of GLI1 protein in cancer

GLI1 is a transcriptional regulator involved in the development of different types of cancer. GLI1 transcriptional activity is regulated within the Hedgehog pathway (canonical activity), but can also be controlled independently (non-canonical activity) in the context of other signaling pathways. Experimental evidences show GLI1 involvement in both small- and non–small-cell lung cancers. Direct inhibition of the protein, in combination with other chemotherapeutic agents, represents a promising strategy for the treatment of different malignancies.

The hedgehog pathway in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of obesity-associated liver diseases and it has become the major cause of cirrhosis in the Western world. The high prevalence of NAFLD-associated advanced liver disease reflects both the high prevalence of obesity-related fatty liver (hepatic steatosis) and the lack of specific treatments to prevent hepatic steatosis from progressing to more serious forms of liver damage, including nonalcoholic steatohepatitis (NASH), cirrhosis, and primary liver cancer. The pathogenesis of NAFLD is complex, and not fully understood. However, compelling evidence demonstrates that dysregulation of the hedgehog (Hh) pathway is involved in both the pathogenesis of hepatic steatosis and the progression from hepatic steatosis to more serious forms of liver damage. Inhibiting hedgehog signaling enhances hepatic steatosis, a condition which seldom results in liver-related morbidity or mortality. In contrast, excessive Hh pathway activation promotes development of NASH, cirrhosis, and primary liver cancer, the major causes of liver-related deaths. Thus, suppressing excessive Hh pathway activity is a potential approach to prevent progressive liver damage in NAFLD. Various pharmacologic agents that inhibit Hh signaling are available and approved for cancer therapeutics; more are being developed to optimize the benefits and minimize the risks of inhibiting this pathway. In this review we will describe the Hh pathway, summarize the evidence for its role in NAFLD evolution, and discuss the potential role for Hh pathway inhibitors as therapies to prevent NASH, cirrhosis and liver cancer.

Beyond cell-cell adhesion: Plakoglobin and the regulation of tumorigenesis and metastasis

Plakoglobin (also known as? -catenin) is a member of the Armadillo family of proteins and a paralog of β -catenin. Plakoglobin is a component of both the adherens junctions and desmosomes, and therefore plays a vital role in the regulation of cell-cell adhesion. Similar to β -catenin, plakoglobin is capable of participating in cell signaling in addition to its role in cell-cell adhesion. In this context, β -catenin has a well-documented oncogenic potential as a component of the Wnt signaling pathway. In contrast, while some studies have suggested a tumor promoting activity of plakoglobin in a cell/malignancy specific context, it generally acts as a tumor/metastasis suppressor. How plakoglobin acts as a growth/metastasis inhibitory protein has remained, until recently, unclear. Recent evidence suggests that plakoglobin may suppress tumorigenesis and metastasis by multiple mechanisms, including the suppression of oncogenic signaling, interactions with various proteins involved in tumorigenesis and metastasis, and the regulation of the expression of genes involved in these processes. This review is primarily focused on various mechanisms by which plakoglobin may inhibit tumorigenesis and metastasis.

Hedgehog signalling in liver pathophysiology

Liver disease remains a leading cause of mortality worldwide despite recent successes in the field of viral hepatitis, because increases in alcohol consumption and obesity are fuelling an epidemic of chronic fatty liver disease for which there are currently no effective medical therapies. About 20% of individuals with chronic liver injury ultimately develop end-stage liver disease due to cirrhosis. Hence, treatments to prevent and reverse cirrhosis in individuals with ongoing liver injury are desperately needed. The development of successful treatments requires an improved understanding of the mechanisms controlling liver disease progression. The liver responds to diverse insults with a conserved wound healing response, suggesting that it might be generally beneficial to optimise pathways that are crucial for effective liver repair. The Hedgehog pathway has emerged as a potential target based on compelling preclinical and clinical data, which demonstrate that it critically regulates the liver's response to injury. Herein, we will summarise evidence of the Hedgehog pathway's role in liver disease and discuss how modulating pathway activity might be applied to improve liver disease outcomes.

Clinical Significance of Gli-1 And Caveolin-1 Expression in the Human Small Cell Lung Cancer

Background: Lung cancer is the leading causes of cancer-related deaths around the world. Abnormal activation of the hedgehog (Hh) signaling pathway has been found to be involved in the occurrence, invasion, and metastasis of cancers. Autophagy also plays a significant role in the growth and metastasis of cancers. However, the correlation between the Hh signaling pathway and autophagy in small cell lung cancer (SCLC) is still poorly understood. This study aimed to investigate the significance of Hh signaling pathway and autophagy in SCLC. Materials and Methods: The expression of the Hh-induced transcriptional factor, glioma associated oncogene-1 (Gli-1) and the autophagy-related molecule caveolin-1 (Cav-1) and their clinical significance was performed to detect and assay by immunohistochemistry in tissue microarray including 70 patients with SCLC. Results: In our study, 47 (67.1%) patients had positive Gli-1 expression, 49 (70.0%) patients had positive Cav-1 expression, and 44 (62.9%) patients had negative fibroblastic Cav-1 expression. In SCLC, Gli-1 expression increased markedly, and was closely associated with decreased fibroblastic Cav-1 expression. Furthermore, we also found that Gli-1 expression was closely associated with increased Cav-1 expression. Conclusions: Our findings suggested that abnormal activation of the Hh signaling pathway is closely related to autophagy in SCLC. We envision that novel targets may come with the further investigation of Gli-1 and Cav-1 in carcinogenesis of SCLC.

Loss of long noncoding RNA FOXF1-AS1 regulates epithelial-mesenchymal transition, stemness and metastasis of non-small cell lung cancer cells

Although recent evidence shows that long noncoding RNAs (lncRNAs) are involved in the regulation of gene expression and cancer progression, the understanding of the role of lncRNAs in lung cancer metastasis is still limited. To identify novel lncRNAs in non-small cell lung cancer (NSCLC), we profile NSCLC tumor and matched normal samples using GeneChip® Human Gene 2.0 ST Array, which provides the most accurate, sensitive, and comprehensive measurement of protein coding and lncRNA transcripts. We identified a panel of key factors dysregulated in lung cancer. Among them, the expression of FOXF1-AS1 was significantly downregulated in lung cancer. Stable overexpression of FOXF1-AS1 inhibits lung cancer cell migration and invasion by regulating EMT. Meanwhile, loss of FOXF1-AS1 mediates stem-like properties of lung cancer cells. Interestingly, we found that FOXF1-AS1 physically associates with PRC2 components EZH2 and loss of FOXF1-AS1 mediates cell migration and stem-like properties require EZH2. Loss of FOXF1-AS1 is also correlated with downregulation of FOXF1 in lung cancer. These results suggested that FOXF1-AS1 might regulate EMT, stemness and metastasis of NSCLC cells via EZH2, indicating it as a therapeutic target for future treatment of NSCLC.

Phase Ib Study of Glasdegib, a Hedgehog Pathway Inhibitor, in Combination with Standard Chemotherapy in Patients with AML or High-Risk MDS

Purpose: This open-label, multicenter, dose-finding, phase Ib study (NCT01546038) evaluated the safety, pharmacokinetics, pharmacodynamics, and clinical activity of the novel Hedgehog pathway Smoothened inhibitor glasdegib (PF-04449913) in patients (N = 52) with acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS).Experimental Design: Glasdegib 100 or 200 mg was administered orally, once daily in 28-day cycles, in combination with low-dose cytarabine (arm A) or decitabine (arm B) to newly diagnosed patients considered not suitable for standard induction chemotherapy, and in combination with cytarabine/daunorubicin (arm C) to fit patients. The study followed a standard 3+3 dose-escalation design. The primary endpoint was dose-limiting toxicity (DLT). Ten additional patients were enrolled in expansion cohorts of arms A (n = 23) and C (n = 22) to confirm the recommended phase II dose (RP2D).Results: No DLTs were observed in arms A and B; 1 DLT (grade 4 neuropathy) occurred in arm C. The most common treatment-related nonhematologic adverse events were mostly grades 1 and 2 in all arms. Muscle spasms, dysgeusia, and alopecia were generally mild. Overall, 16 patients (31%) achieved a complete remission (CR)/CR with incomplete blood count recovery. Note that 100 mg daily was selected as the RP2D for glasdegib in combination with standard chemotherapies in the absence of an estimated MTD in this setting.Conclusions: Treatment with glasdegib in combination with standard chemotherapy was generally well-tolerated and consistent with prior findings, warranting further evaluation of glasdegib-based combinations in patients with AML or high-risk MDS. Clin Cancer Res; 24(10); 2294-303. ©2018 AACR.

Genetic interactions between the hedgehog co-receptors Gas1 and Boc regulate cell proliferation during murine palatogenesis

Abnormal regulation of Sonic hedgehog (Shh) signaling has been described in a variety of human cancers and developmental anomalies, which highlights the essential role of this signaling molecule in cell cycle regulation and embryonic development. Gas1 and Boc are membrane co-receptors for Shh, which demonstrate overlapping domains of expression in the early face. This study aims to investigate potential interactions between these co-receptors during formation of the secondary palate. Mice with targeted mutation in Gas1 and Boc were used to generate Gas1; Boc compound mutants. The expression of key Hedgehog signaling family members was examined in detail during palatogenesis via radioactive in situ hybridization. Morphometric analysis involved computational quantification of BrdU-labeling and cell packing; whilst TUNEL staining was used to assay cell death. Ablation of Boc in a Gas1 mutant background leads to reduced Shh activity in the palatal shelves and an increase in the penetrance and severity of cleft palate, associated with failed elevation, increased proliferation and reduced cell death. Our findings suggest a dual requirement for Boc and Gas1 during early development of the palate, mediating cell cycle regulation during growth and subsequent fusion of the palatal shelves.

SMO Inhibition Modulates Cellular Plasticity and Invasiveness in Colorectal Cancer

HIGHLIGHTS Preliminary results of this work were presented at the 2016 Academic Surgical Congress, Jacksonville (FL), February 2-4 2016 (Original title: Selective Smo-Inhibition Interferes With Cellular Energetic Metabolism In Colorectal Cancer)This study was funded by "Sapienza-University of Rome" (Funds for young researchers) and "AIRC" (Italian Association for Cancer Research)Hedgehog inhibitor was kindly provided by Genentech, Inc.®. Colon Cancer (CC) is the fourth most frequently diagnosed tumor and the second leading cause of death in the USA. Abnormalities of Hedgehog pathway have been demonstrated in several types of human cancers, however the role of Hedgehog (Hh) in CC remain controversial. In this study, we analyzed the association between increased mRNA expression of GLI1 and GLI2, two Hh target genes, and CC survival and recurrence by gene expression microarray from a cohort of 382 CC patients. We found that patients with increased expression of GLI1 showed a statistically significant reduction in survival. In order to demonstrate a causal role of Hh pathway activation in the pathogenesis of CC, we treated HCT 116, SW480 and SW620 CC cells lines with GDC-0449, a pharmacological inhibitor of Smoothened (SMO). Treatment with GDC-0449 markedly reduced expression of Hh target genes GLI1, PTCH1, HIP1, MUC5AC, thus indicating that this pathway is constitutively active in CC cell lines. Moreover, GDC-0449 partially reduced cell proliferation, which was associated with upregulation of p21 and downregulation of CycD1. Finally, treatment with the same drug reduced migration and three-dimensional invasion, which were associated with downregulation of Snail1, the EMT master gene, and with induction of the epithelial markers Cytokeratin-18 and E-cadherin. These results were confirmed by SMO genetic silencing. Notably, treatment with 5E1, a Sonic Hedgehog-specific mAb, markedly reduced the expression of Hedgehog target genes, as well as inhibited cell proliferation and mediated reversion toward an epithelial phenotype. This suggests the existence of a Hedgehog autocrine signaling loop affecting cell plasticity and fostering cell proliferation and migration/invasion in CC cell lines. These discoveries encourage future investigations to better characterize the role of Hedgehog in cellular plasticity and invasion during the different steps of CC pathogenesis.

The protective autophagy activated by GANT-61 in MYCN amplified neuroblastoma cells is mediated by PERK

The proto-oncogene MYC can trigger the unfolded protein response (UPR). The double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase (PERK), one of three primary branches of the UPR, is a key regulator of autophagy, promoting tumorigenesis. Upon activation of PERK, there is an increase in phosphorylation of the eukaryotic initiation factor-2 alpha (eIF2α), which in turn, activates the transcription factor-4 (ATF4), responsible for an increased expression of LC3, a common autophagy marker. PERK is repressed upon GLI1 and GLI2 induction. GANT-61 is an inhibitor of GLI1 and GLI2, known to reduce autophagy in MYCN non-amplified, but not in MYCN amplified neuroblastoma (NB) cells. In our study, we tested the effect of the joint administration of a PERK inhibitor (GSK2606414) and the GLI inhibitor GANT-61 to MYCN amplified and MYCN non-amplified NB cells. Our results suggest that inhibition of PERK impairs GANT-61 induced autophagy in NB cells with MYCN amplification, but had no effect on the MYCN non-amplified NB cells. In summary, PERK seems to be a good therapeutic target for NB. Inhibition of PERK reduces autophagy in MYCN amplified NB cells, thus amplifying the efficacy of the GLI inhibitor GANT-61 in reducing proliferation of this type of cancer cells.

Neoplastic Multifocal Skin Lesions: Biology, Etiology, and Targeted Therapies for Nonmelanoma Skin Cancers

Neoplastic skin lesions are multifocal, diffuse skin infiltrations of particular relevance in the differential diagnosis of ulcerative, nodular, or crusting skin lesions. Nonmelanoma skin cancers (NMSCs), namely, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and also actinic keratosis (AK), are the most common malignant tumors in humans. BCCs do not proliferate rapidly and most of the times do not metastasize, while SCCs are more infiltrative, metastatic, and destructive. AKs are precursor lesions of cutaneous SCCs. The classical therapy of NMSCs makes use of photodynamic therapy associated with chemotherapeutics. With improved understanding of the pathological mechanisms of tumor initiation, progression, and differentiation, a case is made towards the use of targeted chemotherapy with the intent to reduce the cytotoxicity of classical treatments. The present review aims to describe the current state of the art on the knowledge of NMSC, including its risks factors, oncogenes, and skin carcinogenesis, discussing the classical therapy against new therapeutic options.

A dual mechanism of activation of the Sonic Hedgehog pathway in anaplastic thyroid cancer: crosstalk with RAS-BRAF-MEK pathway and ligand secretion by tumor stroma

Sonic Hedgehog (Shh) pathway regulates embryonic development of different organs including the thyroid gland. The aberrant activation of Shh signaling has been found in several types of cancer and according to recent evidences it represents an important regulator of tumor-stroma interaction. In this study, we have analyzed expression, activation and molecular mechanisms regulating the Shh pathway and its involvement in the modulation of tumor stroma interaction in anaplastic thyroid cancer (ATC) cells. Our results suggest that Shh signaling undergoes a dual mechanism of induction in ATC cells: 1) a basal non-canonical Smo-dependent activation of Gli transcription factor that is partly caused by interaction with the RAS/BRAF/MEK oncogenic pathway and is characterized by the absence of Shh ligand expression in thyroid cancer cells and 2) a paracrine response of cancer cells to Shh ligand secreted by tumor stroma (fibroblasts and mesenchymal stromal cells, MSCs) inducing cancer cell migration and in vitro tumorigenesis. Our data therefore suggest Shh as a potential novel therapeutic target in aggressive thyroid cancers.

I131 reinforces antitumor activity of metuximab by reversing epithelial-mesenchymal transition via VEGFR-2 signaling in hepatocellular carcinoma

CD147 is highly expressed in hepatocellular carcinoma (HCC) and associated with the invasion and metastasis of HCC. The efficacy of I¹³¹ -metuximab (I¹³¹ -mab), a newly developed agent that targets CD147, as a radio-immunotherapy for local HCC, has been validated in clinical practice. However, the synergistic anticancer activity and molecular mechanism of different conjugated components within I¹³¹ -mab remain unclear. In this study, the cytological experiments proved that I¹³¹ -mab inhibited the proliferation and invasion of HCC cells. Mechanically, this inhibition effect was mainly mediated by the antibody component part of I¹³¹ -mab, which could reverse the epithelial-mesenchymal transition of HCC cells partially by suppressing the phosphorylation of VEGFR-2. The inhibitory effect of I¹³¹ on HCC cell proliferation and invasion is limited, whereas, when combined with metuximab, I¹³¹ significantly enhanced the sensitivity of HCC cells to CD147-mab and consequently reinforced the anticancer effects of CD147-mab, suggesting that the two components of I¹³¹ -mab exerted synergistic anti-HCC capability. Furthermore, the experiments using SMMC-7721 human HCC xenografts in athymic nude mice showed that I¹³¹ -mab and CD147-mab significantly inhibited the growth of xenograft tumors and that I¹³¹ -mab was more effective than CD147-mab. In conclusion, our results elucidated the mechanism underlying the anti-HCC effects of I¹³¹ -mab and provided a theoretical foundation for the clinical application of I¹³¹ -mab.

MicroRNAs in gynecological cancers: Small molecules with big implications

Gynecological cancers (GCs) are often diagnosed at advanced stages, limiting the efficacy of available therapeutic options. Thus, there remains an urgent and unmet need for innovative research for the efficient clinical management of GC patients. Research over past several years has revealed the enormous promise of miRNAs. These small non-coding RNAs can aid in the diagnosis, prognosis and therapy of all major GCs, viz., ovarian cancers, cervical cancers and endometrial cancers. Mechanistic details of the miRNAs-mediated regulation of multiple biological functions are under constant investigation, and a number of miRNAs are now believed to influence growth, proliferation, invasion, metastasis, chemoresistance and the relapse of different GCs. Modulation of tumor microenvironment by miRNAs can possibly explain some of their reported biological effects. miRNA signatures have been proposed as biomarkers for the early detection of GCs, even the various subtypes of individual GCs. miRNA signatures are also being pursued as predictors of response to therapies. This review catalogs the knowledge gained from collective studies, so as to assess the progress made so far. It is time to ponder over the knowledge gained, so that more meaningful pre-clinical and translational studies can be designed to better realize the potential that miRNAs have to offer.

Patched1 patterns Fibroblast growth factor 10 and Forkhead box F1 expression during pulmonary branch formation

Hedgehog (Hh) signalling, Fibroblast growth factor 10 (Fgf10) and Forkhead box F1 (Foxf1) are each individually important for directing pulmonary branch formation but their interactions are not well understood. Here we demonstrate that Hh signalling is vital in regulating Foxf1 and Fgf10 expression during branching. The Hedgehog receptor Patched1 (Ptch1) was conditionally inactivated in the lung mesenchyme by Dermo1-Cre in vivo or using a recombinant Cre recombinase protein (HNCre) in lung cultures resulting in cell autonomous activation of Hh signalling. Homozygous mesenchymal Ptch1 deleted embryos (Dermo1Cre+/-;Ptch1^lox/lox) showed secondary branching and lobe formation defects. Fgf10 expression is spatially reduced in the distal tip of Dermo1Cre+/-;Ptch1^lox/lox lungs and addition of Fgf10 recombinant protein to these lungs in culture has shown partial restoration of branching, indicating Ptch1 function patterns Fgf10 to direct lung branching. Foxf1 expression is upregulated in Dermo1Cre+/-;Ptch1^lox/lox lungs, suggesting Foxf1 may mediate Hh signalling effects in the lung mesenchyme. In vitro HNCre-mediated Ptch1 deleted lung explants support the in vivo observations, with evidence of mesenchyme hyperproliferation and this is consistent with the previously reported role of Hh signalling in maintaining mesenchymal cell survival. Consequently it is concluded that during early pseudoglandular stage of lung development Ptch1 patterns Fgf10 and regulates Foxf1 expression in the lung mesenchyme to direct branch formation and this is essential for proper lobe formation and lung function.

Neurovascular patterning cues and implications for central and peripheral neurological disease

The highly branched nervous and vascular systems run along parallel trajectories throughout the human body. This stereotyped pattern of branching shared by the nervous and vascular systems stems from a common reliance on specific cues critical to both neurogenesis and angiogenesis. Continually emerging evidence supports the notion of later-evolving vascular networks co-opting neural molecular mechanisms to ensure close proximity and adequate delivery of oxygen and nutrients to nervous tissue. As our understanding of these biologic pathways and their phenotypic manifestations continues to advance, identification of where pathways go awry will provide critical insight into central and peripheral nervous system pathology.

Dual Inhibition of Hedgehog and c-Met Pathways for Pancreatic Cancer Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the most chemotherapy- and radiotherapy-resistant tumors. The c-Met and Hedgehog (Hh) pathways have been shown previously by our group to be key regulatory pathways in the primary tumor growth and metastases formation. Targeting both the HGF/c-Met and Hh pathways has shown promising results in preclinical studies; however, the benefits were not readily translated into clinical trials with PDAC patients. In this study, utilizing mouse models of PDAC, we showed that inhibition of either HGF/c-Met or Hh pathways sensitize the PDAC tumors to gemcitabine, resulting in decreased primary tumor volume as well as significant reduction of metastatic tumor burden. However, prolonged treatment of single HGF/c-Met or Hh inhibitor leads to resistance to these single inhibitors, likely because the single c-Met treatment leads to enhanced expression of Shh, and vice versa. Targeting both the HGF/c-Met and Hh pathways simultaneously overcame the resistance to the single-inhibitor treatment and led to a more potent antitumor effect in combination with the chemotherapy treatment. Mol Cancer Ther; 16(11); 2399-409. ©2017 AACR.

The Hedgehog-GLI pathway in embryonic development and cancer: implications for pulmonary oncology therapy

Transcriptional regulation and epigenetic mechanisms closely control gene expression through diverse physiological and pathophysiological processes. These include the development of germ layers and post-natal epithelial cell-tissue differentiation, as well as, involved with the induction, promotion and/or progression of human malignancies. Diverse studies have shed light on the molecular similarities and differences involved in the stages of embryological epithelial development and dedifferentiation processes in malignant tumors of epithelial origin, of which many focus on lung carcinomas. In lung cancer, several transcriptional, epigenetic and genetic aberrations have been described to partly arise from environmental risk factors, but ethnic genetic predisposition factors may also play a role. The classification of the molecular hallmarks of cancer has been essential to study and achieve a comprehensive view of the interaction networks between cell signaling pathways and functional roles of the transcriptional and epigenetic regulatory mechanisms. This has in turn increased understanding on how these molecular networks are involved in embryo-layers and malignant diseases development. Ultimately, a major biomedicine goal is to achieve a thorough understanding of their roles as diagnostic, prognostic and treatment response indicators in lung oncological patients. Recently, several notable cell-signaling pathways have been studied based on their contribution to promoting and/or regulating the engagement of different cancer hallmarks, among them genome instability, exacerbated proliferative signaling, replicative immortality, tumor invasion-metastasis, inflammation, and immune-surveillance evasion mechanisms. Of these, the Hedgehog-GLI (Hh) cell-signaling pathway has been identified as a main molecular contribution into several of the abovementioned functional embryo-malignancy processes. Nonetheless, the systematic study of the regulatory epigenetic and transcriptional mechanisms has remained mostly unexplored, which could identify the interaction networks between specific biomarkers and/or new therapeutic targets in malignant tumor progression and resistance to lung oncologic therapy. In the present work, we aimed to revise the most important up-to-date experimental and clinical findings in biology, embryology and cancer research regarding the Hh pathway. We explore the potential control of the transcriptional-epigenetic programming versus reprogramming mechanisms associated with its Hh-GLI cell signaling pathway members. Last, we present a summary of this information to systematically integrate the Hh signaling pathway to identify and propose novel compound strategies or better oncological therapeutic schemes for lung cancer patients.

Human CAFs promote lymphangiogenesis in ovarian cancer via the Hh-VEGF-C signaling axis

Cancer-associated fibroblasts (CAFs) play a pivotal role in the development and progression of many human cancers. Recent studies have shown that Hedgehog (Hh) signalling modulates the stromal microenvironment and prepares a suitable niche for tumour metastasis. However, the detailed molecular mechanisms underlying CAF-mediated lymphangiogenesis have not been fully elucidated. Therefore, our goal is to illustrate whether Hh ligands can activate Hh signalling in CAFs in a paracrine fashion and elucidate the effect of CAFs on lymphangiogenesis. We determined here that Sonic Hedgehog (SHH) secreted by ovarian cancer (OC) cells activated Hh signalling in CAFs and promoted the proliferation of CAFs. Moreover, we co-injected SHH-overexpressing OC cells and CAFs in a xenograft model and found that the CAFs accelerated tumourigenesis and lymphangiogenesis in OC. Mechanistically, we found that SHH secreted by the OC cells induced VEGF-C expression in CAFs. Inhibition of Hh signalling in CAFs decreased VEGF-C expression and diminished the positive role of CAFs in supporting tumourigenesis and lymphangiogenesis in a murine xenograft model. Our results demonstrate that CAFs constitute a supportive niche for cancer lymphangiogenesis via the Hh/VEGF-C signalling axis and provide evidence for the clinical application of Hh inhibitors in the treatment of OC.

Transplacental exposure to environmental carcinogens: Association with childhood cancer risks and the role of modulating factors

Biological responses to carcinogens from environmental exposure during adulthood are modulated over years or decades. Conversely, during transplacental exposure, the effects on the human foetus change within weeks, intertwining with developmental mechanisms: even short periods of transplacental exposure may be imprinted in the organism for a lifetime. The pathways leading to childhood and juvenile cancers, such as leukaemias, neuroblastoma/brain tumours, hepatoblastoma, and Willm's tumour involve prenatally-induced genomic, epigenomic and/or non-genomic effects caused by xenobiotics. Pregnant women most often live in complex environmental settings that cause transplacental exposure of the foetus to xenobiotic mixtures. Mother-child biomonitoring should integrate the analysis of chemicals/radiation present in the living and workplace environment with relevant risk modulators related to life style. The interdisciplinary approach for transplacental cancer risk assessment in high-pressure areas should be based on an integrated model for mother-child exposure estimation via profiling the exposure level by water quality analysis, usage of emission grids, and land use maps.

27-hydroxycholesterol: A novel player in molecular carcinogenesis of breast and prostate cancer

Several studies have suggested an etiological role for hypercholesterolemia in the pathogenesis of breast cancer and prostate cancer (PCa). However, the molecular mechanisms that underlie and mediate the hypercholesterolemia-fostered increased risk for breast cancer and PCa are yet to be determined. The discovery that the most abundant cholesterol oxidized metabolite in the plasma, 27 hydroxycholesterol (27-OHC), is a selective estrogen receptor modulator (SERM) and an agonist of Liver X receptors (LXR) partially fills the void in our understanding and knowledge of the mechanisms that may link hypercholesterolemia to development and progression of breast cancer and PCa. The wide spectrum and repertoire of SERM and LXR-dependent effects of 27-OHC in the context of all facets and aspects of breast cancer and prostate cancer biology are reviewed in this manuscript in a very comprehensive manner. This review highlights recent findings pertaining to the role of 27-OHC in breast cancer and PCa and delineates the signaling mechanisms involved in the governing of different facets of tumor biology, that include tumor cell proliferation, epithelial-mesenchymal transition (EMT), as well as tumor cell invasion, migration, and metastasis. We also discuss the limitations of contemporary studies and lack of our comprehension of the entire gamut of effects exerted by 27-OHC that may be relevant to the pathogenesis of breast cancer and PCa. We unveil and propose potential future directions of research that may further our understanding of the role of 27-OHC in breast cancer and PCa and help design therapeutic interventions against endocrine therapy-resistant breast cancer and PCa.

Negative prognostic effect of low nuclear GLI1 expression in glioblastomas

The hedgehog signaling plays supportive roles in various aspects of tumorigenesis. Increased expression of the key component, GLI1, has been shown to correlate with poor prognosis in many types of cancers. We aimed to investigate the effect of GLI1 expression in glioblastoma focusing on the nuclear localization. Immunohistochemistry for GLI1, GLI2, PTCH1, SMO, and SHH were done in 140 glioblastoma tissues, and the staining was graded. For GLI1, nuclear and cytoplasmic expression was separately assessed. No significant correlation was found between clinicopathologic parameters and expression grades of the five proteins. Low nuclear GLI1 expression was associated with a worse progression-free survival while overall survival was not significantly affected. In contrast, cytoplasmic GLI1 expression did not have a prognostic effect. PTCH1 expression correlated with nuclear GLI1 expression without exerting a significant prognostic effect. Analysis of the TCGA-glioblastoma dataset revealed that low GLI1 mRNA level also correlated with a poor prognosis for both overall and progression-free survival. The adverse effect of low nuclear GLI1 expression in glioblastomas is in contrast with the negative prognostic effect of high GLI1 expression reported in non-cranial malignancies. The relative impact of hedgehog signaling among other oncogenic pathways in the brain may be responsible for the difference. The different implication of GLI1 expression in glioblastomas needs to be considered in studies of hedgehog signaling-targeted therapy.

Silibinin Treatment Inhibits the Growth of Hedgehog Inhibitor-Resistant Basal Cell Carcinoma Cells via Targeting EGFR-MAPK-Akt and Hedgehog Signaling

Basal cell carcinoma (BCC) is the most common skin malignancy. Deregulated hedgehog signaling plays a central role in BCC development; therefore, hedgehog inhibitors have been approved to treat locally advanced or metastatic BCC. However, the development of resistance to hedgehog inhibitors is the major challenge in effective treatment of this disease. Herein, we evaluated the efficacy of a natural agent silibinin to overcome resistance with hedgehog inhibitors (Sant-1 and GDC-0449) in BCC cells. Silibinin (25-100 μm) treatment for 48 h strongly inhibited growth and induced death in ASZ001, Sant-1-resistant (ASZ001-Sant-1) and GDC-0449-resistant (ASZ001-GDC-0449) BCC cells. Furthermore, colony-forming ability of ASZ001, ASZ001-Sant-1 and ASZ001-GDC-0449 cells was completely inhibited by silibinin treatment. Molecular analysis showed that silibinin treatment decreased the level of phosphorylated EGFR (Tyrosine 1173) and total EGFR in ASZ001-Sant-1 cells, key signaling molecules responsible for BCC resistance toward hedgehog inhibitors. Further, silibinin treatment decreased the phosphorylated Akt (Serine 473), phosphorylated ERK1/2 (Threonine 202/Tyrosine 204), cyclin D1 and Gli-1 level but increased the SUFU expression in ASZ001-Sant-1-resistant cells. Silibinin treatment of ASZ001-Sant-1-resistant cells also decreased bcl-2 but increased cleaved caspase 3 and PARP cleavage, suggesting induction of apoptosis. Together, these results support silibinin use to target hedgehog inhibitor-resistant BCC cells.

Hedgehog inhibition enhances efficacy of radiation and cisplatin in orthotopic cervical cancer xenografts

BACKGROUND

The Hedgehog (Hh) pathway is upregulated in cervical cancer and associated with poor outcome. We explored the effects of Hh pathway inhibition in combination with RTCT in a patient derived orthotopic cervical cancer xenograft model (OCICx).

METHODS

5E1, a monoclonal antibody for SHH, or Sonidegib (LDE225), a clinical SMO inhibitor (Novartis) were added to RTCT. We investigated tumour growth delay, metastasis and GI toxicity using orthotopic cervical cancer xenografts models. The xenografts were treated with radiotherapy (15 × 2 Gy daily fractions over 3 weeks) and weekly cisplatin 4 mg kg^-1 concurrently, with or without 5E1 or Sonidegib (LDE225). The Hh inhibitors were administered by subcutaneous injection (5E1; 20 mg kg^-1 weekly for 3 weeks), or by oral gavage (Sonidegib; 60 mg kg^-1 daily for 3 weeks).

RESULTS

We observed that both Hh inhibitors administered with RTCT were well tolerated and showed increased tumour growth delay, and reduced metastasis, with no increase in acute GI-toxicity relative to RTCT alone.

CONCLUSIONS

Our data suggest Hh can be a valid therapeutic target in cervical cancer and supports data suggesting a potential therapeutic role for targeting Hh in patients undergoing RTCT. This warrants further investigation in clinical trials.

Galectin-1 from cancer-associated fibroblasts induces epithelial-mesenchymal transition through β1 integrin-mediated upregulation of Gli1 in gastric cancer

BACKGROUND

Gastric cancer (GC) is characterized by the excessive deposition of extracellular matrix, which is thought to contribute to this tumor's malignant behavior. Epithelial-mesenchymal transition (EMT) is regarded as a crucial contributing factor to cancer progression. Galectin-1 (Gal-1), a β-galactoside-binding protein abundantly expressed in activated cancer-associated fibroblasts (CAFs), has been reported to be involved in GC progression and metastasis by binding to β1 integrin, which, in turn, can bind to matrix proteins and activate intracellular cascades that mediate EMT. Increasing evidence suggests that abnormal activation of the hedgehog (Hh) signaling pathway enhances GC cell migration and invasion. The purpose of our study is to explore the role of Gal-1 in the GC progression and metastasis as well as the regulatory mechanism.

METHODS

We hypothesized that Gal-1 binding to β1 integrin would lead to paracrine signaling between CAFs and GC cells, mediating EMT by upregulating Gli1. Invasion and metastasis effects of the Gal-1 and Gli1 were evaluated using wound healing and invasion assay following transfection with mimics. Additionally, to facilitate the delineation of the role of the Hh signaling in GC, we monitored the expression level of associated proteins. We also evaluated the effects of β1 integrin on these processes. Furthermore, Gal-1 and Gli1 expression in GC patient samples were examined by immunohistochemistry and western blot to determine the correlation between their expression and clinicopathologic characteristics. The Kaplan-Meier method and Cox proportional hazards model were used to analyze the relationship of expression with clinical outcomes.

RESULTS

Gal-1 was found to induce EMT, GC cell migration and invasion. Further data showed that Gal-1 up-regulated Gli1 expression. β1 integrin was responsible for Gal-1-induced Gli1 expression and EMT. In clinical GC tissue, it confirmed a positive relationship between Gal-1 and Gli1 expression. Importantly, their high expression is correlated to poor prognosis.

CONCLUSION

Gal-1 from CAFs binds to a carbohydrate structure in β1 integrin and plays an important role in the development of GC by inducing GC metastasis and EMT through targeting Gli1. This study highlights the potential therapeutic value of Gal-1 for suppression of GC metastasis.

New strategies for targeting drug combinations to overcome mutation-driven drug resistance

Targeted therapies are suggested as an effective alternative for patients with cancer that harbor mutations, but treatment outcomes are frequently limited by primary or acquired drug resistance. The present review describes potential mechanisms of primary or acquired drug resistances to provide a resource for considering how to be overcome. We focus on strategies of targeted drug combinations to minimize the development of drug resistance within the context how resistance develops. Strategies benefit from the combined use of "omics" technologies, i.e., high-throughput functional genomics data, pharmacogenomics, or genome-wide CRISPR-Cas9 screening, to analyze and design targeted drug combinations for mutation-driven drug resistance. We also introduce new insights towards pathway-centric combined therapies as an alternative to overcome the heterogeneity and benefit patient prognoses.

Current ideas on the biology of IGFBP-6: More than an IGF-II inhibitor?

IGFBP-6 binds IGF-II with higher affinity than IGF-I and it is a relatively specific inhibitor of IGF-II actions. More recently, IGFBP-6 has also been reported to have IGF-independent effects on cell proliferation, survival, differentiation and migration. IGFBP-6 binds to several ligands in the extracellular space, cytoplasm and nucleus. These interactions, together with activation of distinct intracellular signaling pathways, may contribute to its IGF-independent actions; for example, IGF-independent migration induced by IGFBP-6 involves interaction with prohibitin-2 and activation of MAP kinase pathways. A major challenge for the future is delineating the relative roles of the IGF-dependent and -independent actions of IGFBP-6, which may lead to the development of therapeutic approaches for diseases including cancer.

Inhibition of Pancreatic Cancer Cell-Induced Paracrine Hedgehog Signaling by Liver X Receptor Agonists and Oxy16, a Naturally Occurring Oxysterol

The widespread involvement of the Hedgehog (Hh) signaling pathway in human malignancies has driven efforts to develop Hh pathway inhibitors as anti-cancer agents. The majority of these agents antagonize Smoothened (Smo), a plasma membrane-associated signal transducer molecule. However, several such Smo antagonists have failed in clinical trials to benefit patients with cancers that arise from aberrant Hh signaling (which often bypasses Smo). In this study, we report that a naturally occurring oxysterol, 20α, 22(R)-dihydroxycholesterol (Oxy16), a known metabolite in the biosynthesis of steroid hormones, strongly inhibits Hh signaling induced in C3H10T1/2 embryonic fibroblasts and NIH3T3-E1 fibroblasts through a mechanism that is independent of liver X receptor (LXR) activation. We demonstrate that Oxy16 inhibits Hh signaling in Suppressor of Fused (Sufu) null mouse embryonic fibroblast (MEF) cells, indicating that its inhibitory effect on Hh signaling is epistatic to Sufu. We further demonstrate that Oxy16 inhibits Gli1 transcriptional activity in NIH3T3-E1 cells overexpressing Gli1 and a Gli-dependent reporter construct. Altogether, data presented here suggest that Oxy16 may be a suitable starting point for the development of new drugs that inhibit Hh signaling downstream of Smo. By targeting aberrant Hh signaling, such novel Hh pathway inhibitors could significantly broaden the range of clinical applications compared to existing Smo antagonists. Furthermore, the present study adds a new facet to the spectrum of Hh pathway modulation that naturally occurring oxysterol derivatives are capable of, ranging from allosteric activation of the pathway via Smo binding to inhibition of the pathway downstream of Smo. J. Cell. Biochem. 118: 499-509, 2017. © 2016 Wiley Periodicals, Inc.

Requirement of Smad4 from Ocular Surface Ectoderm for Retinal Development

Microphthalmia is characterized by abnormally small eyes and usually retinal dysplasia, accounting for up to 11% of the blindness in children. Right now there is no effective treatment for the disease, and the underlying mechanisms, especially how retinal dysplasia develops from microphthalmia and whether it depends on the signals from lens ectoderm are still unclear. Mutations in genes of the TGF-β superfamily have been noted in patients with microphthalmia. Using conditional knockout mice, here we address the question that whether ocular surface ectoderm-derived Smad4 modulates retinal development. We found that loss of Smad4 specifically on surface lens ectoderm leads to microphthalmia and dysplasia of retina. Retinal dysplasia in the knockout mice is caused by the delayed or failed differentiation and apoptosis of retinal cells. Microarray analyses revealed that members of Hedgehog and Wnt signaling pathways are affected in the knockout retinas, suggesting that ocular surface ectoderm-derived Smad4 can regulate Hedgehog and Wnt signaling in the retina. Our studies suggest that defective of ocular surface ectoderm may affect retinal development.

Hedgehog Proteins Consume Steroidal CYP17A1 Antagonists: Potential Therapeutic Significance in Advanced Prostate Cancer

Abiraterone, a potent inhibitor of the human enzyme CYP17A1 (cytochrome P450c17), provides a last line of defense against ectopic androgenesis in advanced prostate cancer. Herein we report an unprecedented off-target interaction between abiraterone and oncogenic hedgehog proteins. Our experiments indicate that abiraterone and its structural congener, galeterone, can replace cholesterol as a substrate in a specialized biosynthetic event of hedgehog proteins, known as cholesterolysis. The off-target reaction generates covalent hedgehog-drug conjugates. Cell-based reporter assays indicate that these conjugates activate hedgehog signaling when present in the low nanomolar range. Because hedgehog signaling is implicated in prostate cancer progression, and abiraterone is administered to treat advanced stages of the disease, this off-target interaction may have therapeutic significance.

Histone deacetylase inhibitors for the treatment of cancer stem cells

HDAC inhibitors are a promising group of epigenetic drugs that show the ability to induce apoptosis in cancer stem cells.