Inhibition of the hedgehog pathway in advanced basal-cell carcinoma

Pulmonary metastases: a rare manifestation of the most common cancer

Basal cell carcinoma (BCC) is the most common human malignancy but rarely metastasises. We report on two patients with symptomatic lung metastases and a past history of recurrent BCC excisions. In our first patient, a heavy smoker with multiple lung lesions, histology of a resected nodule was first reported as non-small cell lung cancer but a repeat nodule biopsy a year later was recognised as a pulmonary metastasis from primary cutaneous BCC. Our second patient, a young never-smoker with two previous BCC, was confirmed as having a pulmonary metastasis from BCC on the lung resection specimen. Pulmonary metastasis from an unidentified primary site is a common clinical situation. These patients emphasise the importance of considering the most common cancer as a potential primary.

Vismodegib

Vismodegib (GDC-0449), an orally bioavailable small-molecule inhibitor of Hedgehog signaling, was recently approved by the U.S. Food and Drug Administration for the treatment of basal cell carcinoma that is either metastatic or locally advanced in patients who are not candidates for surgical resection or radiation. Given the absence of previously defined effective drug therapy for this disease, approval was granted primarily on the basis of outcome of a nonrandomized parallel cohort phase II study of 99 patients with advanced basal cell carcinoma, with a primary endpoint of objective response rate. Response rates of 30.3% and 42.9% were observed in metastatic and locally advanced cohorts in this study, respectively, associated with median progression-free survival in both cohorts of 9.5 months. Ongoing clinical investigations include evaluation of the potential efficacy of vismodegib in a variety of diseases and in combination with other agents. The mechanism of action, preclinical and clinical data, and potential utility in other disease contexts are reviewed here.

Efficacy and safety of vismodegib in advanced basal-cell carcinoma

BACKGROUND

Alterations in hedgehog signaling are implicated in the pathogenesis of basal-cell carcinoma. Although most basal-cell carcinomas are treated surgically, no effective therapy exists for locally advanced or metastatic basal-cell carcinoma. A phase 1 study of vismodegib (GDC-0449), a first-in-class, small-molecule inhibitor of the hedgehog pathway, showed a 58% response rate among patients with advanced basal-cell carcinoma.

METHODS

In this multicenter, international, two-cohort, nonrandomized study, we enrolled patients with metastatic basal-cell carcinoma and those with locally advanced basal-cell carcinoma who had inoperable disease or for whom surgery was inappropriate (because of multiple recurrences and a low likelihood of surgical cure, or substantial anticipated disfigurement). All patients received 150 mg of oral vismodegib daily. The primary end point was the independently assessed objective response rate; the primary hypotheses were that the response rate would be greater than 20% for patients with locally advanced basal-cell carcinoma and greater than 10% for those with metastatic basal-cell carcinoma.

RESULTS

In 33 patients with metastatic basal-cell carcinoma, the independently assessed response rate was 30% (95% confidence interval [CI], 16 to 48; P=0.001). In 63 patients with locally advanced basal-cell carcinoma, the independently assessed response rate was 43% (95% CI, 31 to 56; P<0.001), with complete responses in 13 patients (21%). The median duration of response was 7.6 months in both cohorts. Adverse events occurring in more than 30% of patients were muscle spasms, alopecia, dysgeusia (taste disturbance), weight loss, and fatigue. Serious adverse events were reported in 25% of patients; seven deaths due to adverse events were noted.

CONCLUSIONS

Vismodegib is associated with tumor responses in patients with locally advanced or metastatic basal-cell carcinoma. (Funded by Genentech; Erivance BCC ClinicalTrials.gov number, NCT00833417.).

Inhibiting the hedgehog pathway in patients with the basal-cell nevus syndrome

BACKGROUND

Dysregulated hedgehog signaling is the pivotal molecular abnormality underlying basal-cell carcinomas. Vismodegib is a new orally administered hedgehog-pathway inhibitor that produces objective responses in locally advanced and metastatic basal-cell carcinomas.

METHODS

We tested the anti-basal-cell carcinoma efficacy of vismodegib in a randomized, double-blind, placebo-controlled trial in patients with the basal-cell nevus syndrome at three clinical centers from September 2009 through January 2011. The primary end point was reduction in the incidence of new basal-cell carcinomas that were eligible for surgical resection (surgically eligible) with vismodegib versus placebo after 3 months; secondary end points included reduction in the size of existing basal-cell carcinomas.

RESULTS

In 41 patients followed for a mean of 8 months (range, 1 to 15) after enrollment, the per-patient rate of new surgically eligible basal-cell carcinomas was lower with vismodegib than with placebo (2 vs. 29 cases per group per year, P<0.001), as was the size (percent change from baseline in the sum of the longest diameter) of existing clinically significant basal-cell carcinomas (-65% vs. -11%, P=0.003). In some patients, all basal-cell carcinomas clinically regressed. No tumors progressed during treatment with vismodegib. Patients receiving vismodegib routinely had grade 1 or 2 adverse events of loss of taste, muscle cramps, hair loss, and weight loss. Overall, 54% of patients (14 of 26) receiving vismodegib discontinued drug treatment owing to adverse events. At 1 month, vismodegib use had reduced the hedgehog target-gene expression by basal-cell carcinoma by 90% (P<0.001) and diminished tumor-cell proliferation, but apoptosis was not affected. No residual basal-cell carcinoma was detectable in 83% of biopsy samples taken from sites of clinically regressed basal-cell carcinomas.

CONCLUSIONS

Vismodegib reduces the basal-cell carcinoma tumor burden and blocks growth of new basal-cell carcinomas in patients with the basal-cell nevus syndrome. The adverse events associated with treatment led to discontinuation in over half of treated patients. (Funded by Genentech and others; ClinicalTrials.gov number, NCT00957229.).

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

Sant-75 is a newly identified potent inhibitor of the hedgehog pathway. We designed a diversity-oriented synthesis program, and synthesized a series of Sant-75 analogues, which lays the foundation for further investigation of the structure–activity relationship of this important class of hedgehog-pathway inhibitors.

Cutting edge in medical management of cutaneous oncology

Traditional chemotherapy has resulted in only a modest response, if any, for the 3 most common cutaneous malignancies of basal cell carcinoma, squamous cell carcinoma, and melanoma. Recent advances in understanding of the defects in the pathways driving tumorigenesis have changed the way that we think of these cancers and paved the way to targeted therapy for specific tumors. In this review, we will introduce the novel systemic treatments currently available for these cancers in the context of what is understood about the tumor pathogenesis. We will also introduce ongoing studies that will hopefully broaden our options for highly effective and tolerable treatment.

How I treat CML blast crisis

Blast crisis (BC) remains the major challenge in the management of chronic myeloid leukemia (CML). It is now generally accepted that BC is the consequence of continued BCR-ABL activity leading to genetic instability, DNA damage, and impaired DNA repair. Most patients with BC carry multiple mutations, and up to 80% show additional chromosomal aberrations in a nonrandom pattern. Treatment with tyrosine kinase inhibitors has improved survival in BC modestly, but most long-term survivors are those who have been transplanted. Patients in BC should be treated with a tyrosine kinase inhibitor according to mutation profile, with or without chemotherapy, with the goal of achieving a second chronic phase and proceeding to allogeneic stem cell transplantation as quickly as possible. Although long-term remissions are rare, allogeneic stem cell transplantation provides the best chance of a cure in BC. Investigational agents are not likely to provide an alternative in the near future. In view of these limited options, prevention of BC by a rigorous and early elimination of BCR-ABL is recommended. Early response indicators should be used to select patients for alternative therapies and early transplantation. Every attempt should be made to reduce or eliminate BCR-ABL consistent with good patient care as far as possible.

Novel therapy for therapy-resistant mantle cell lymphoma: multipronged approach with targeting of hedgehog signaling

Mantle cell lymphoma (MCL) is one of the most aggressive B-cell lymphomas with a median patient survival of only 5-7 years. The failure of existing therapies is mainly due to disease relapse when therapy-resistant tumor cells remain after chemotherapy. Therefore, development and testing of novel therapeutic strategies to target these therapy-resistant MCL are needed. Here, we developed an in vivo model of therapy-resistant MCL by transplanting a patient-derived MCL cell line (Granta 519) into NOD/SCID mice followed by treatment with combination chemotherapy. Cytomorphologic, immunophenotypic, in vitro and in vivo growth analyses of these therapy-resistant MCL cells confirm their MCL origin and resistance to chemotherapy. Moreover, quantitative real-time PCR revealed the upregulation of GLI transcription factors, which are mediators of the hedgehog signaling pathway, in these therapy-resistant MCL cells. Therefore, we developed an effective therapeutic strategy for resistant MCL by treating the NOD/SCID mice bearing Granta 519 MCL with CHOP chemotherapy to reduce tumor burden combined with GLI-antisense oligonucleotides or bortezomib, a proteosome inhibitor, to target therapy-resistant MCL cells that remained after chemotherapy. This regimen was followed by treatment with MCL-specific cytotoxic T lymphocytes to eliminate all detectable leftover minimal residual disease. Mice treated with this strategy showed a significantly increased survival and decreased tumor burden compared to the mice in all other groups. Such therapeutic strategies that combine chemotherapy with targeted therapy followed by tumor-specific immunotherapy are effective and have excellent potential for clinical application to provide long-term, disease-free survival in MCL patients.

Targeting the Hedgehog signaling pathway for cancer therapy

INTRODUCTION

Hedgehog (Hh) signaling pathway plays key roles in embryonic development, formation and maintenance of cancer stem cells (CSCs) and acquisition of epithelial-to-mesenchymal transition (EMT). Since CSCs and EMT are important biological factors responsible for cancer cell invasion, metastasis, drug resistance and tumor recurrence, the Hh signaling pathway is believed to be an important target for cancer therapy.

AREAS COVERED

In recent years, small-molecule inhibitors of Hh signaling have been synthesized for cancer treatment. Clinical trials using these inhibitors are being conducted to determine their toxicity profiles and efficacies. In addition, nutraceuticals (such as isoflavones, curcumin, vitamin D, etc) have been shown to inhibit cancer growth through downregulation of Hh signaling.

EXPERT OPINION

Inhibition of Hh signaling is important for suppression of cancer growth, invasion, metastasis and recurrence in cancer therapy. However, targeting only one molecule in Hh signaling may not be sufficient to kill cancer cells because cancers show deregulation of multiple signals. Therefore, utilizing new technologies to determine alterations in Hh and other signals for individuals and designing combination strategies with small-molecule Hh inhibitors, nutraceuticals and other chemotherapeutics in targeted personalized therapy could have a significant effect on improving the overall survival of patients with cancers.

Exploiting the cancer genome: strategies for the discovery and clinical development of targeted molecular therapeutics

Our biological understanding of the molecular basis of cancer has benefited from advances in basic research, accelerated recently by cancer genome sequencing and other high-throughput, genome-wide profiling technologies. Given the diverse heterogeneity among tumors, the traditional cytotoxic chemotherapy and one-size-fits-all approaches to cancer discovery and development are not appropriate for molecularly targeted agents. Selection of new drug targets is based on achieving cancer selectivity through exploiting specific dependencies and vulnerabilities predicted from tumor genetics. Discovery of highly target-selective agents is enhanced by integrating multiple modern technologies, particularly structure-based design. Efficient clinical evaluation requires smart, hypothesis-testing studies using validated pharmacodynamic and predictive biomarkers. We discuss and exemplify biomarker-driven clinical development and the concept of the Pharmacologic Audit Trail. We detail the exciting approaches offered by drugging the cancer genome, focusing on blocking oncogene addiction, drugging the oncogenic lipid kinome, addressing nononcogene addiction, exploiting synthetic lethality, and overcoming apoptotic resistance, leading to personalized molecular medicine.

The mesenchymal tumor microenvironment: a drug-resistant niche

Drug and radiation resistance represent a challenge for most anticancer therapies. Diverse experimental approaches have provided evidence that the tumor-associated microenvironment constitutes both a protective shell that impedes drug or radiation access and a permissive or promotive microenvironment that encourages a nurturing cancer (i.e., cancer stem cell) niche where tumor cells overcome treatment- and cancer-induced stresses. Better understanding of the effects of the tumor microenvironment on cancer cells before, during and immediately after chemo- or radiotherapy is imperative to design new therapies aimed at targeting this tumor-protective niche. This review summarizes some of the known mesenchymal stromal effects that account for drug resistance, the main signal transduction pathways associated with this resistance and the therapeutic efforts directed to increase the success of current therapies. Special emphasis is given to environment-mediated drug resistance in general and to cell adhesion-mediated drug resistance in particular.

Inhibition of hedgehog signalling prevents experimental fibrosis and induces regression of established fibrosis

OBJECTIVES

Tissue fibrosis is a leading cause of death in patients with systemic sclerosis (SSc). Effective antifibrotic treatments are not available. Here, the authors investigated inhibition of hedgehog signalling by targeting Smoothened (Smo) as a novel antifibrotic approach.

METHODS

The activation status of the hedgehog pathway was assessed by immunohistochemistry for Gli transcription factors and by quantification of hedgehog target genes. Hedgehog signalling was inhibited by the selective inhibitor LDE223 and by small interfering RNA against Smo in the models of bleomycin-induced dermal fibrosis and in tight-skin-1 mice.

RESULTS

Hedgehog signalling is activated in SSc and in murine models of SSc. Inhibition of Smo either by LDE223 or by small interfering RNA prevented dermal thickening, myofibroblast differentiation and accumulation of collagen upon challenge with bleomycin. Targeting Smo also exerted potent antifibrotic effects in tight-skin-1 mice and did prevent progression of fibrosis and induced regression of pre-established fibrosis.

CONCLUSIONS

Inhibition of hedgehog signalling exerted potent antifibrotic effects in preclinical models of SSc in both preventive and therapeutic settings. These findings might have direct translational implications because inhibitors of Smo are already available and yielded promising results in initial clinical trials.

Embryonic signaling pathways and rhabdomyosarcoma: contributions to cancer development and opportunities for therapeutic targeting

Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence, accounting for approximately 7% of childhood cancers. Current therapies include nonspecific cytotoxic chemotherapy regimens, radiation therapy, and surgery; however, these multimodality strategies are unsuccessful in the majority of patients with high-risk disease. It is generally believed that these tumors represent arrested or aberrant skeletal muscle development, and, accordingly, developmental signaling pathways critical to myogenesis such as Notch, WNT, and Hedgehog may represent new therapeutic targets. In this paper, we summarize the current preclinical studies linking these embryonic pathways to rhabdomyosarcoma tumorigenesis and provide support for the investigation of targeted therapies in this embryonic cancer.

STAT3 activation and aberrant ligand-dependent sonic hedgehog signaling in human pulmonary adenocarcinoma

The Sonic hedgehog (SHH) signaling and STAT3 pathways play important roles during carcinogenesis with possible interaction. To determine the association of the activation of SHH signaling pathway and STAT3 pathway in carcinogenesis of human non-small cell lung carcinomas (NSCLC), firstly we examined the expression of SHH signaling molecules including SHH, Gli1(glioma-associated oncogene homolog 1) and HHIP (Hh interacting protein), as well as p-STAT3 (phosphorylation at Tyr705) by immunohistochemistry in 87 cases of NSCLC, 12 atypical adenomatous hyperplasia (AAH) and 20 adjacent normal lung tissues. The expression of SHH, Gli1, HHIP and p-STAT3 was detected respectively in 87/87(100%), 74/87(85.1%), 75/87(86.2%) and 54/87(62.1%) of the NSCLC cases, but not in the adjacent normal lung parenchyma. Ligand-dependent SHH pathway activation and STAT3 signaling activation were observed in most cases of NSCLC, and the high SHH pathway activation rate and STAT3 activation rate were significantly higher in adenocarcinoma compared with squamous cell carcinomas and large cell carcinomas (P<0.05). Both SHH and STAT3 pathway activation level correlated with histological grade in adenocarcinoma, being higher in well-differentiated types (P<0.05). Furthermore, high SHH pathway activation and p-STAT3 expression were also detected in 10/12(83.3%) of AAH cases as well as in most cases of early-stage adenocarcinoma - adenocarcinoma in situ (AIS) and minimally invasive adenocarcinomas (MIA). Correlation analysis showed that p-STAT3 protein expression level was correlated positively with ligand-dependent activation level of SHH signaling in adenocarcinoma (r(s)=0.585, P=0.000) and AAH (r(s)=0.996, P=0.000). We speculated that activation of STAT3 could up-regulate SHH gene expression directly or indirectly, and thereby activated SHH signaling resulting in lung tumor cell ontogeny. To explore the interactional mechanism, we then performed serial transient co-transfection assay in human pulmonary adenocarcinoma cell line H441 cells, and the results confirmed STAT3 activation can up-regulate SHH gene expression indirectly. In conclusion, aberrant ligand-dependent SHH signaling activation occurs frequently in NSCLC. The signaling plays a more active role in adenocarcinoma, and is an early event in carcinogenesis of lung adenocarcinoma. The involvement of STAT3 pathway activation might function in inducing the process.

Metastatic basal cell carcinoma in the era of hedgehog signaling pathway inhibitors

BACKGROUND

Inhibition of the hedgehog signaling pathway (HHSP) for the treatment of locally advanced basal cell carcinoma (BCC) and metastatic BCC (mBCC) has produced promising results. Typically, mBCC is not taken into consideration during the workup of a patient with multifocal metastatic disease who has a history of BCC. The objective of the current review, in which the authors evaluated the time from the first BCC diagnosis to metastasis, location of disease, and radiographic features, was to contribute to the general knowledge and awareness among providers, patients, and support groups about mBCC and to provide an outlook for the future of treatments for mBCC. A literature review on mBCC and a review of records from patients with mBCC who presented to Virginia G. Piper Cancer Center Clinical Trials (an oncology clinical trials center) were conducted. The clinical and radiographic findings of 22 patients with mBCC who were evaluated at that center from the initiation of smoothened (SMO) antagonist trials were analyzed along with a review of BCC epidemiology and pathogenesis, the HHSP, and current and future treatments for this rare presentation of the most common malignancy. The results indicated that, in the last 5 years, there has been a plethora of new agents targeting SMO, a key component of the HHSP that, for the majority of patients with mBCC, may be a good match for targeting tumor genetic vulnerability. Like with other targeted therapy for uncommon malignancies, such as chronic myelogenous leukemia and gastrointestinal stromal tumors, the authors anticipate that there will be clinical development of next-generation HHSP inhibitors to combat mBCCs that are nonresponsive to or progress on current SMO antagonists.

Transformation of a chronic myeloproliferative neoplasm to acute myelogenous leukemia: does anything work?

The BCR/ABL-negative myeloproliferative neoplasms (MPNs) of essential thrombocythemia, polycythemia vera, and primary myelofibrosis, over the natural course of their disease, have an increasing predisposition to transform to overt acute myeloid leukemia (AML)-most appropriately referred to as MPN-blast phase (MPN-BP). Although this transformation is a rare event, once AML has occurred, it is associated with a poor response to therapy and short survival. The molecular events leading to transformation are poorly defined. Currently, no therapy other than allogeneic stem cell transplantation (ASCT) has been demonstrated to alter the natural history of this disease. Multiple therapeutic investigations are currently ongoing, including early ASCT, hypomethylating agents, and JAK2 inhibition, to try to alter the course of the disease and improve outcomes. This review focuses on the latest advances in our understanding of the biology of leukemic transformation and current clinical therapies that are available for this patient population.

Neurotoxicity of biologically targeted agents in pediatric cancer trials

Biologically targeted agents offer the promise of delivering specific anticancer effects while limiting damage to healthy tissue, including the central and peripheral nervous systems. During the past 5-10 years, these agents were examined in preclinical and adult clinical trials, and are used with increasing frequency in children with cancer. This review evaluates current knowledge about neurotoxicity from biologically targeted anticancer agents, particularly those in pediatric clinical trials. For each drug, neurotoxicity data are reviewed in adult (particularly studies of brain tumors) and pediatric studies when available. Overall, these agents are well tolerated, with few serious neurotoxic effects. Data from younger patients are limited, and more neurotoxicity may occur in the pediatric population because these agents target pathways that control not only tumorigenesis but also neural maturation. Further investigation is needed into long-term neurologic effects, particularly in children.

Activation of the Sonic Hedgehog pathway in thyroid neoplasms and its potential role in tumor cell proliferation

The sonic hedgehog (SHH) pathway is activated in several types of malignancy and plays an important role in tumor cell proliferation and tumorigenesis. SHH binding to a 12-pass transmembrane receptor, Patched (PTCH), leads to freeing of Smoothened (SMO) and subsequent activation of GLI transcription factors. In the present study, we analyzed the expression of SHH, PTCH, SMO, and GLI1 in 31 follicular thyroid adenomas (FTA), 8 anaplastic thyroid carcinomas (ATC), and 51 papillary thyroid carcinomas (PTC) by immunohistochemical staining. More than 65% of FTA, PTC, and ATC specimens stained positive for SHH, PTCH, SMO, and GLI. However, the expression of the genes encoding these four molecules did not correlate with any clinicopathologic parameters, including the age, gender, the status of BRAF gene mutation, tumor stage, local invasion, and metastasis. Three thyroid tumor cell lines (KAT-18, WRO82, and SW1736) all expressed the genes encoding these four molecules. 5-Bromo-2-deoxyuridine labeling and MTT cell proliferation assays revealed that cyclopamine (CP), an inhibitor of the SHH pathway, was able to inhibit the proliferation of KAT-18 and WRO82 cells more effectively than SW1736 cells. CP led to the arrest of cell cycle or apoptosis. Knockdown of SHH and GLI expression by miRNA constructs that target SHH or GLI mRNA in KAT-18 and SW1736 cells led to the inhibition of cell proliferation. Our results suggest that the SHH pathway is widely activated in thyroid neoplasms and may have potential as an early marker of thyroid cancer or as a potential therapeutic target for thyroid cancer treatment.

Moving molecular targeted drug therapy towards personalized medicine: issues related to clinical trial design

With the event of new Molecular targets, clinical trial design requirements to perform these trials are changing. This paper discusses some of the considerations that need to be taken into account when designing a trial, including those trials that assess combinations of targets.

BMPs and their clinical potentials

Bone morphogenetic protein (BMP) signaling in diseases is the subject of an overwhelming array of studies. BMPs are excellent targets for treatment of various clinical disorders. Several BMPs have already been shown to be clinically beneficial in the treatment of a variety of conditions, including BMP-2 and BMP-7 that have been approved for clinical application in nonunion bone fractures and spinal fusions. With the use of BMPs increasingly accepted in spinal fusion surgeries, other therapeutic approaches targeting BMP signaling are emerging beyond applications to skeletal disorders. These approaches can further utilize next-generation therapeutic tools such as engineered BMPs and ex vivo- conditioned cell therapies. In this review, we focused to provide insights into such clinical potentials of BMPs in metabolic and vascular diseases, and in cancer. [BMB reports 2011; 44(10): 619-634].

Ectopic overexpression of Sonic Hedgehog (Shh) induces stromal expansion and metaplasia in the adult murine pancreas

Ligand-dependent activation of the Hedgehog (Hh) signaling pathway has been implicated in both tumor initiation and metastasis of pancreatic ductal adenocarcinoma (PDAC). Prior studies in genetically engineered mouse models (GEMMs) have assessed the role of Hh signaling by cell autonomous expression of a constitutively active Gli2 within epithelial cells. On the contrary, aberrant pathway reactivation in the human exocrine pancreas occurs principally as a consequence of Sonic Hh ligand (Shh) overexpression from epithelial cells. To recapitulate the cognate pathophysiology of Hh signaling observed in the human pancreas, we examined GEMM where Hh ligand is conditionally overexpressed within the mature exocrine pancreas using a tamoxifen-inducible Elastase-Cre promoter (Ela-CreERT2;LSL-mShh). We also facilitated potential cell autonomous epithelial responsiveness to secreted Hh ligand by generating compound transgenic mice with concomitant expression of the Hh receptor Smoothened (Ela-CreERT2;LSL-mShh;LSL-mSmo). Of interest, none of these mice developed intraductal precursor lesions or PDAC during the follow-up period of up to 12 months after tamoxifen induction. Instead, all animals demonstrated marked expansion of stromal cells, consistent with the previously described epithelial-to-stromal paracrine Hh signaling. Hh responsiveness was mirrored by the expression of primary cilia within the expanded mesenchymal compartment and the absence within mature acinar cells. In the absence of cooperating mutations, Hh ligand overexpression in the mature exocrine pancreas is insufficient to induce neoplasia, even when epithelial cells coexpress the Smo receptor. This autochthonous model serves as a platform for studying epithelial stromal interactions in pancreatic carcinogenesis.

Pathways involved in Drosophila and human cancer development: the Notch, Hedgehog, Wingless, Runt, and Trithorax pathway

Animal models are established tools to study basic questions of biology in a systematic way. They have greatly facilitated our understanding of the mechanisms by which nature forms and maintains organisms. Much of the knowledge on molecular changes underlying the development of organisms originates from research in the fruit fly model Drosophila melanogaster. Vertebrate models including the mouse and zebrafish model, but also other animal models coming from different corners of the animal kingdom have shown that much of the basic machinery of development is essentially identical, not just in all vertebrates but in all major phyla of invertebrates too. Moreover, key elements of this machinery have been demonstrated to be involved in recurrent molecular abnormalities detected in tumor-tissue from patients, indicating their implication in the genesis of human cancer. Thus, research in this field has become a common topic for both biologists and hemato-oncologists. In this review, we summarize current knowledge on some of these key elements and molecular pathways such as Notch, Hedgehog, Wingless, Runt, and Trithorax that have been originally described and studied in animal models and which seem to play a major role in the pathophysiology and targeted management of human cancer.

Molecular pathways: the role of primary cilia in cancer progression and therapeutics with a focus on Hedgehog signaling

Abnormal Hedgehog (Hh) pathway activity has been reported in many cancers, including basal cell carcinomas, medulloblastomas, rhabdomyosarcomas, glioblastomas, and breast and prostate cancers. For this reason, the Hh pathway is a flourishing area for development of anticancer drugs such as Hh ligand antagonists (e.g., 5E1 and robotnikinin), Smo inhibitors (e.g., GDC-0449 and IPI-926), and Gli transcriptional activity inhibitors (e.g., GANT58 and GANT61). It is now clear that primary cilia are required for activation of the Hh pathway in normal vertebrate cells. It is in the primary cilium that both positive and negative effectors of the Hh pathway are processed by posttranslational modifications. In many cancers, preliminary results suggest that primary cilia are lost. As drugs that inhibit different steps of the Hh pathway are developed, it will be important to consider how these drugs will function in the context of primary cilia in the tumor environment. Here, we discuss why some of the Hh inhibitors may be ineffective if primary cilia are lost on cancer cells. Understanding the relationships between clinical inhibitors of the Hh pathway and the presence or absence of primary cilia may turn out to be critical for targeting these therapeutics to the correct population of patients and improving their efficacy. Further work is needed in this area to maximize the potential of these exciting therapeutic targets.

Hedgehog pathway activation in human transitional cell carcinoma of the bladder

BACKGROUND

The Hedgehog (Hh) signalling pathway functions as an organiser in embryonic development. Recent studies have shown constitutive activation of this pathway in various malignancies, but its role in bladder cancer remains poorly studied.

METHODS

Expression levels of 31 genes and 9 microRNAs (miRNAs) involved in the Hh pathway were determined by quantitative real-time RT-PCR in 71 bladder tumour samples (21 muscle-invasive (MIBC) and 50 non-muscle-invasive (NMIBC) bladder cancers), as well as in 6 bladder cancer cell lines.

RESULTS

The SHH ligand gene and Gli-inducible target genes (FOXM1, IGF2, OSF2, H19, and SPP1) were overexpressed in tumour samples as compared with normal bladder tissue. SHH overexpression was found in 96% of NMIBC and 52% of MIBC samples, as well as in two bladder cancer cell lines. Altered expression of miRNAs supported their oncogene or tumour-suppressor gene status. In univariate analysis, high expression levels of PTCH2, miRNA-92A, miRNA-19A, and miRNA-20A were associated with poorer overall survival in MIBC (P=0.02, P=0.012, P=0.047, and P=0.036, respectively).

CONCLUSION

We observed constitutive activation of the Hh pathway in most NMIBC and about 50% of MIBC. We also found that some protein-coding genes and miRNAs involved in the Hh pathway may have prognostic value at the individual level.

Notch, wnt, and hedgehog pathways in rhabdomyosarcoma: from single pathways to an integrated network

Rhabdomyosarcoma (RMS) is the most common type of soft tissue sarcoma in children. Regarding histopathological criteria, RMS can be divided into 2 main subtypes: embryonal and alveolar. These subtypes differ considerably in their clinical phenotype and molecular features. Abnormal regulation or mutation of signalling pathways that regulate normal embryonic development such as Notch, Hedgehog, and Wnt is a recurrent feature in tumorigenesis. Herein, the general features of each of the three pathways, their implication in cancer and particularly in RMS are reviewed. Finally, the cross-talking among these three pathways and the possibility of better understanding of the horizontal communication among them, leading to the development of more potent therapeutic approaches, are discussed.

Hedgehog pathway as a drug target: Smoothened inhibitors in development

Emerging laboratory and clinical investigations demonstrate that Hedgehog signaling (Hh) represents a novel therapeutic target in various human cancers. This conserved signaling pathway precisely regulates self-renewal and terminal differentiation in embryonic development, but is typically silenced in adult tissues, with reactivation usually only during tissue repair. Aberrant Hh pathway signaling has been implicated in the pathogenesis, self-renewal, and chemotherapy resistance of a growing number of solid and hematologic malignancies. Major components of the Hh pathway include the Hh ligands (Sonic, Desert, and Indian), the transmembrane receptor Patched, the signal transducer Smoothened (Smo), and transcription factors Gli1–3 which regulate the transcription of Hh target genes. Mutations in Hh pathway genes, increased Hh signaling in tumor stroma, and Hh overexpression in self-renewing cells (cancer stem cells) have been described, and these different modes of Hh signaling have implications for the design of Hh pathway inhibitors and their integration into conventional treatment regimens. Discovery of a naturally-occurring Smo inhibitor, cyclopamine, and the identification of Hh pathway mutations and over expression in cancer cells prompted the development of several cyclopamine derivatives. Encouraging laboratory and in vivo data has resulted in Phase I and II clinical trials of Smo inhibitors. In this review, we will discuss the current understanding of Hh pathway signaling in malignancy and Smo antagonists in development. Recent data with these agents shows that they are well-tolerated and may be effective for subsets of patients. Challenges remain for appropriate patient selection and the optimal combination and sequence of these targeted therapies into current treatment paradigms.

Periocular cutaneous malignancies: a review of the literature

BACKGROUND

The periocular skin is susceptible to numerous benign and malignant neoplasms. Periocular malignancies may present differently, behave more aggressively, and pose greater challenges for treatment and repair than malignancies at other cutaneous sites. Between 5% and 10% of cutaneous malignancies occur periorbitally, with basal cell carcinoma reported as the most common malignant periocular tumor, followed by squamous cell carcinoma, sebaceous gland carcinoma, cutaneous melanoma, Merkel cell carcinoma, and other rare tumors.

OBJECTIVE

To review the current literature on cutaneous malignancies of the periocular region pertaining to etiology, incidence, clinical presentation, differential diagnosis, complications, and treatment options.

MATERIALS AND METHODS

An extensive literature review was conducted using PubMed, searching for articles on periocular and periorbital cutaneous malignancies.

CONCLUSIONS

Timely diagnosis and management of periocular malignancies is essential because of their proximity to and potential to invade vital structures such as the orbit, sinuses, and brain. Surgical excision remains the standard of care for the majority of periorbital malignancies, but given the sensitive anatomic location, tissue-sparing techniques with margin control such as Mohs micrographic surgery are the preferred method for most nonmelanoma skin cancers. Depending on tumor type, other treatment modalities may include radiation, chemotherapy, cryosurgery, topical medications, and photodynamic therapy.

Gli inhibitor GANT61 causes apoptosis in myeloid leukemia cells and acts in synergy with rapamycin

Aberrant reactivation of Gli signaling has been described in a wide variety of human cancers and rapamycin can down-regulate Gli pathway in some solid tumors. In this study, we attempt to define the cytotoxic effect of Gli inhibitor on AML cells. And the regulation action of rapamycin on Gli in AML cells also has been assessed. Gli inhibitor GANT61 caused growth arrest and apoptosis in AML cells. Rapamycin decreased not only the Gli protein and mRNA expressions but also expression of the Gli-luciferase reporter in AML cells. Synergism effect between GANT61 and rapamycin was found in Kasumi-1, HL-60 and U937 cell lines. The results suggest that aberrant Gli activation is a feature of some myeloid leukemic cells and Gli activiation can be down-regulated by rapamycin.

Biological and clinical relevance of stem cells in pancreatic adenocarcinoma

Cancer stem cells (CSC) have been identified in a growing number of human malignancies. CSC are functionally defined by their ability to self-renew and recapitulate tumors in the ectopic setting, and a growing number of studies have shown that they display other functional characteristics, such as invasion and drug resistance. These unique functional properties implicate a role for CSC in clinical consequences, such as initial tumor formation, relapse following treatment, metastasis, and resistance, suggesting they are a major factor in directing clinical outcomes. Pancreatic adenocarcinoma is a highly-aggressive disease with a propensity for early metastasis and drug resistance. Tumorigenic pancreatic cancer cells have been identified using the cell surface antigens CD44, CD24, and CD133, as well as the high expression of aldehyde dehydrogenase (ALDH). In vitro and in vivo studies have shown that ALDH- and CD133-expressing pancreatic CSC have a greater propensity for metastasis, and ALDH-expressing CSC have been shown to be resistant to conventional chemotherapy. In clinical samples from patients with resected pancreatic adenocarcinoma, the presence of ALDH-expressing CSC was associated with worse overall survival. The development of CSC-targeting therapies might be important in changing the clinical outcomes of patients with this disease, and others and we have begun to identify novel compounds that block CSC function. This review will discuss the biological and clinical relevance of CSC in pancreatic cancer, and will discuss novel therapeutic strategies to target them.

Latest advances and current challenges in the treatment of multiple myeloma

Effectively treating patients with multiple myeloma is challenging. The development of therapeutic regimens over the past decade that incorporate the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide has been the cornerstone of improving the outcome of patients with myeloma. Although these treatment regimens have improved patient survival, nearly all patients eventually relapse. Our improved understanding of the biology of the disease and the importance of the microenvironment has translated into ongoing work to help overcome the challenge of relapse. Several classes of agents including next-generation proteasome inhibitors, immunomodulatory agents, selective histone-deacetylase inhibitors, antibody and antitumor immunotherapy approaches are currently undergoing preclinical and clinical evaluation. This Review provides an update on the latest advances in the treatment of multiple myeloma. In particular, we focus on novel therapies including modulating protein homeostasis, kinases inhibitors, targeting accessory cells and cytokines, and immunomodulatory agents. A discussion of the challenges associated with these therapeutic approaches is also presented.

Iatrogenic immunosuppression and cutaneous malignancy

Patients with autoimmune and inflammatory conditions often receive long-term immunosuppressive therapy. Some of the largest patient populations with iatrogenic immunosuppression include patients who have received solid-organ transplants or who have rheumatoid arthritis or psoriasis. Although treatments improve patient outcomes, individuals with immunosuppression subsequently may have an increased risk of skin cancer, including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma.

FISH and chips: the recipe for improved prognostication and outcomes for children with medulloblastoma

Rapidly evolving genomic technologies have permitted progressively detailed studies of medulloblastoma biology in recent years. These data have increased our understanding of the molecular pathogenesis of medulloblastoma, identified prognostic markers, and suggested future avenues for targeted therapy. Although current randomized trials are still stratified based largely on clinical variables, the use of molecular markers is approaching routine use in the clinic. In particular, integrated genomics has uncovered that medulloblastoma comprises four distinct molecular and clinical variants: WNT, sonic hedgehog (SHH), group 3, and group 4. Children with WNT medulloblastoma have improved survival, whereas those with group 3 medulloblastoma have a dismal prognosis. Additionally, integrated genomics has shown that adult medulloblastoma is molecularly and clinically distinct from the childhood variants. Prognostic and predictive markers identified by genomics should drive changes in stratification of treatment protocols for medulloblastoma patients on clinical trials once they can be demonstrated to be reliable, reproducible, and practical. Cases with excellent prognoses (WNT cases) should be considered for therapy de-escalation, whereas those with bleak prognoses (group 3 cases) should be prioritized for experimental therapy. In this review, we will summarize the genomic data published over the past decade and attempt to interpret its prognostic significance, relevance to the clinic, and use in upcoming clinical trials.

Recent advances in pathway-targeted cancer drug therapies emerging from cancer genome analysis

Substantial recent progress has been reported in the context of implementing 'personalized' cancer medicine, informed by tumor genotyping. The recent FDA approvals of crizotinib, an ALK kinase inhibitor that has yielded significant clinical benefit in ALK-translocated lung cancers, and vemurafenib, a BRAF-selective kinase inhibitor that has demonstrated dramatic clinical efficacy in BRAF mutant melanoma patients, define the new landscape for tailored cancer drug therapy. However, acquired drug resistance remains a significant obstacle to the long-term benefit of such treatments. Here, we review these and other recent developments that are paving the way for future efforts to optimize the clinical utility of pathway-targeted cancer drug therapies.

Basal cell carcinoma - molecular biology and potential new therapies

Basal cell carcinoma (BCC) of the skin, the most common malignancy in individuals of mixed European descent, is increasing in incidence due to an aging population and sun exposure habits. The realization that aberrant activation of Hedgehog signaling is a pathognomonic feature of BCC development has opened the way for exciting progress toward understanding BCC biology and translation of this knowledge to the clinic. Genetic mouse models closely mimicking human BCCs have provided answers about the tumor cell of origin, and inhibition of Hedgehog signaling is emerging as a potentially useful targeted therapy for patients with advanced or multiple BCCs that have hitherto lacked effective treatment.

Hedgehog-EGFR cooperation response genes determine the oncogenic phenotype of basal cell carcinoma and tumour-initiating pancreatic cancer cells

Inhibition of Hedgehog (HH)/GLI signalling in cancer is a promising therapeutic approach. Interactions between HH/GLI and other oncogenic pathways affect the strength and tumourigenicity of HH/GLI. Cooperation of HH/GLI with epidermal growth factor receptor (EGFR) signalling promotes transformation and cancer cell proliferation in vitro. However, the in vivo relevance of HH-EGFR signal integration and the critical downstream mediators are largely undefined. In this report we show that genetic and pharmacologic inhibition of EGFR signalling reduces tumour growth in mouse models of HH/GLI driven basal cell carcinoma (BCC). We describe HH-EGFR cooperation response genes including SOX2, SOX9, JUN, CXCR4 and FGF19 that are synergistically activated by HH-EGFR signal integration and required for in vivo growth of BCC cells and tumour-initiating pancreatic cancer cells. The data validate EGFR signalling as drug target in HH/GLI driven cancers and shed light on the molecular processes controlled by HH-EGFR signal cooperation, providing new therapeutic strategies based on combined targeting of HH-EGFR signalling and selected downstream target genes.

Epidemiology of basal cell carcinoma

Basal cell carcinoma is the most common malignant neoplasm in humans and its incidence has increased over the last decades. Its high frequency significantly burdens the health system, making the disease a public health issue. Despite the low mortality rates and the rare occurrence of metastases, the tumor may be locally invasive and relapse after treatment, causing significant morbidity. Exposure to ultraviolet radiation is the main environmental risk factor associated with its cause. However, other elements of risk are described, such as light skin phototypes, advanced age, family history of skin carcinoma, light eyes and blond hair, freckles in childhood and immunosuppression. Behavioral aspects such as occupational sun exposure, rural labor and sunburns at a young age also play a role. Between 30% and 75% of the sporadic cases are associated with patched hedgehog gene mutation, but other genetic changes are also described. The tumor is commonly found in concomitance with skin lesions related to chronic sun exposure, such as actinic keratoses, solar lentigines and facial telangiectasia. The prevention of basal cell carcinoma is based on the knowledge of risk factors, early diagnosis and treatment, as well as on the adoption of specific measures, particularly in susceptible populations. The authors present a review of the epidemiology of basal cell carcinoma.

Molecular Characterization of a Patient's Small Cell Carcinoma of the Ovary of the Hypercalcemic Type

Small cell carcinoma of the ovary of the hypercalcemic type (SCCOHT) is a very rare tumor type that mainly affects young women. We report a 21-year old woman with SCCOHT. The patient initially presented with stage T3AN1MX disease and treated with surgery. The patient then received 8 cycles of multi-agent chemotherapy including cisplatin, bleomycin, cyclophosphamide, doxorubicin, and etoposide. Upon relapse, the patient underwent total abdominal hysterectomy, followed by chemotherapy with gemcitabine. The patient subsequently received radiation therapy and chemotherapy with bevacizumab, irinotecan and docetaxel. She passed away approximately 5 months after the second surgery and with her prior permission an immediate autopsy was performed. We examined the gene expression and copy number profiles of the tumor tissue samples obtained from the autopsy and compared them to normal ovary tissues. Our results indicated that although this tumor did not harbor chromosomal abnormalities nor gene copy number changes, there were significant gene expression changes in a number of genes/pathways. More than 5,000 genes showed significant differential expression in the tumor when compared to normal ovary tissue. Pathway enrichment analysis further identified several pathways/processes including the Vitamin D receptor signaling and the hedgehog signaling pathways to be significantly dysregulated. The gene expression profiling also suggests a number of agents such as pazopanib, bortezomib, 5-azacytidine, and PARP inhibitors as treatment options to possibly explore in future trials against this disease.

The GLI genes as the molecular switch in disrupting Hedgehog signaling in colon cancer

The Hedgehog (HH) signaling pathway leads to activation of GLI, which transcriptionally regulate target genes. Regulated HH signaling activity is critical during embryogenesis while aberrantly activated HH signaling is evident in a variety of human cancers. Canonical HH signaling engages the transmembrane receptor Patched (PTCH) and the signaling intermediate Smoothened (SMO) to activate GLI1 and GLI2. In addition GLI1 and GLI2 are activated by non-canonical oncogenic signaling pathways to further drive HH-dependent survival. We have demonstrated in human colon carcinoma cells that inhibition of the RAS/RAF pathway by U0126 decreases p-ERK protein expression and also inhibits GLI-luciferase activity and GLI1 mRNA and protein levels. Of importance is the demonstration that targeting of SMO (using cyclopamine) has minimal effect on cell survival in comparison to the inhibition of GLI (using GANT61), which induced extensive cell death in 7/7 human colon carcinoma cell lines. Genetic inhibition of the function of GLI1 and GLI2 by transient transfection of the C-terminus deleted repressor GLI3R, reduced proliferation and induced cleavage of caspase-3 and cell death in HT29 cells, similar to the effects of GANT61. Mechanistically, downstream of GLI1 and GLI2 inhibition, γH2AX (a marker of DNA double strand breaks) expression was upregulated, and γH2AX nuclear foci were demonstrated in cells that expressed GLI3R. Activation of the ATM/Chk2 axis with co-localization of γH2AX and p-Chk2 nuclear foci were demonstrated following GLI1/GLI2 inhibition. GANT61 induced cellular accumulation at G1/S and early S with no further progression before cells became subG1, while cDNA microarray gene profiling demonstrated downregulation of genes involved in DNA replication, the DNA damage response, and DNA repair, mechanisms that are currently being pursued. These studies highlight the importance of targeting the GLI genes downstream of SMO for terminating HH-dependent survival, suggesting that GLI may constitute a molecular switch that determines the balance between cell survival and cell death in human colon carcinoma.

Hedgehog inhibition with the orally bioavailable Smo antagonist LDE225 represses tumor growth and prolongs survival in a transgenic mouse model of islet cell neoplasms

BACKGROUND

This study was designed to evaluate the role of the hedgehog pathway in tumor progression of murine islet cell tumors. Blockade of aberrant hedgehog activation has recently been proposed as a therapeutic target, but effects in models of islet cell tumors with a new orally bioavailable Smoothened (Smo) antagonist LDE225 have not been examined.

MATERIAL AND METHODS

To assess in vivo effects, transgenic Rip1Tag2 mice, which develop islet cell neoplasms, were treated with vehicle or LDE225 (80 mg/kg/d) from week 5 until death. The resected pancreata were evaluated macroscopically and microscopically by iummohistochemsistry. Quantitative real-time polymerase chain reaction was performed for hedgehog target genes with RNA from islet, isolated from treated and untreated Rip1Tag2 mice.

RESULTS

LDE225 significantly reduced tumor volume by 95% compared with untreated control mice. Hedgehog inhibition with LDE225 significantly prolonged median survival in the used transgenic mouse model (105 vs 116 days; P = 0.02). Quantitative real-time polymerase chain reaction for downstream hedgehog target genes demonstrated significant downregulation in the islet cell tumors of Rip1Tag2 mice treated with LDE225, confirming the ability to achieve effective pharmacologic levels of LDE225 within the desired tissue site, in vivo.

CONCLUSION

This is the first study to show that the orally bioavailable Smo antagonist LDE225 may provide a new option for therapy of islet cell neoplasms.