gant-61 and Neoplasms

Important steps in embryonic development are governed by the Hedgehog (Hh) signaling pathway, an evolutionary conserved signal transduction cascade. However, Hh activity not only is crucial during embryo formation but also is involved in adult tissue repair and in several malignancies. Particularly due to its link to cancer, small molecule Hh pathway inhibitors have been developed and the first compounds have been approved for use in Hh-driven basal cell carcinoma. Almost all advanced Hh inhibitors target the critical signaling component Smoothened (SMO), but preclinical research has identified additional compounds that can block the Hh pathway along its entire signaling cascade, which, in light of emerging drug resistance occurring with SMO inhibitors, is of high importance. Herein we give an overview on currently known Hh pathway inhibitors, delineating their respective strengths and weaknesses and describing potential drug targeting strategies to interfere with Hh signaling in different cancer settings.

Topics: Animals; Antineoplastic Agents; Carcinoma, Basal Cell; Drug Approval; Drug Design; Hedgehog Proteins; Humans; Ligands; Molecular Targeted Therapy; Neoplasms; Receptors, G-Protein-Coupled; Signal Transduction; Smoothened Receptor; Veratrum Alkaloids

Since its discovery by C. Nüsslein-Volhard and E. F. Wieschaus, hedgehog (hh) signaling has come a long way. Today it is regarded as a key regulator in embryogenesis where it governs processes like cell proliferation, differentiation, and tissue patterning. Furthermore, in adults it is involved in the maintenance of stem cells, and in tissue repair and regeneration. But hh signaling has a second-much darker-face: it plays an important role in several types of human cancers where it promotes growth and enables proliferation of tumor stem cells. The etiology of medulloblastoma and basal cell carcinoma is tightly linked to aberrant hh activity, but also cancers of the prostate, the pancreas, the colon, the breasts, rhabdomyosarcoma, and leukemia, are dependent on irregular hh activity. Recent clinical studies have shown that hh signaling can be the basis of an important new class of therapeutic agents with far-reaching implications in oncology. Thus, modulation of hh signaling by means of small molecules has emerged as a valuable tool in combating these hh-dependent cancers. Cyclopamine, a unique natural product with a fascinating history, was the first identified inhibitor of hh signaling and its story is closely linked to the progress in the whole field. In this review we will trace the story of cyclopamine, give an overview on the biological modes of hh signaling both in untransformed and malignant cells, and finally present potent modulators of the hh pathway-many of them already in clinical studies. For more than 30 years now the knowledge on hh signaling has grown steadily-an end to this development is far from being conceivable.

Topics: Antineoplastic Agents; Hedgehog Proteins; Humans; Neoplasms; Signal Transduction; Veratrum Alkaloids

Topics: Antineoplastic Agents; Drug Discovery; Hedgehog Proteins; Humans; Neoplasms; Signal Transduction; Transcription Factors; Zinc Finger Protein GLI1

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Synergism; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; Humans; Indoles; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasms; Pyridines; Pyrimidines; Signal Transduction; Sulfonamides; Zinc Finger Protein GLI1

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

Topics: Cell Line, Tumor; Cell Proliferation; Cell Survival; Disease Progression; Gene Expression Regulation, Neoplastic; Hedgehog Proteins; HeLa Cells; Humans; Jurkat Cells; Neoplasms; Nuclear Proteins; Pyridines; Pyrimidines; Signal Transduction; Zinc Finger Protein GLI1; Zinc Finger Protein Gli2

The successful use of SMO inhibitors in tumors with activating mutations in hedgehog signaling raised interests in their exploitation against other malignancies. The role of hedgehog signaling in pediatric malignancies remains unclear.. We investigated the hedgehog signaling and its inhibition in a panel of 18 tumor cell lines derived from six of the most common and highly aggressive pediatric tumor types. None of the cell lines was known to stem from tumors with activating hedgehog mutations. Tetrazolium-based assays (MTT and MTS) and BrdU assays were used to analyze cell viability and proliferation after exposure to SANT1 and GANT61. Expression analysis of hedgehog signaling members and cyclins was performed by quantitative real-time PCR and Western blot.. Key members of hedgehog signaling (SHH, PTCH1, SMO, GLI1, GLI2 and SUFU) were expressed in all cell lines. In 50% of the cell lines viability was significantly increased by SHH exposure. Stimulation was not restricted to distinct tumor types, but related to cell lines with higher mRNA levels of PTCH1, SMO, GLI1 and GLI2. SMO inhibition by SANT1 moderately decreased cell viability with GI50s between 28 and 93 µmol/l. Sensitivity to SANT1 was not related to distinct tumor types. The GLI inhibitor GANT61 inhibited cell viability and proliferation more effectively than SANT1.. Our preclinical data provide evidence that hedgehog signaling is active and can be stimulated by PTCH1 ligands in various pediatric tumors. We suggest further evaluation of GLI inhibitors as inhibitors of hedgehog signaling for the treatment of the investigated tumor types.

Topics: Antineoplastic Agents; Blotting, Western; Cell Line, Tumor; Child; Hedgehog Proteins; Humans; Neoplasms; Piperazines; Pyrazoles; Pyridines; Pyrimidines; Real-Time Polymerase Chain Reaction; Receptors, G-Protein-Coupled; RNA, Messenger; Signal Transduction; Smoothened Receptor; Transcription Factors; Zinc Finger Protein GLI1

Multiple lines of evidence implicate that aberrant activation of Hedgehog (Hh) signaling is involved in a variety of human cancers. However, the molecular mechanisms underlying how cancer cells respond to Hh inhibition remain to be elucidated. In this study, we found that blockade of Hh signaling suppresses cell proliferation in human cancer cells. Microarray analysis revealed that differentially expressed genes (DEGs) in human cancer cells are enriched in autophagy pathway in response to the inhibition of Hh signaling. Interestingly, inhibition of Hh signaling induced autophagy, whereas activation of Hh signaling by ligand treatments prevented the induction of autophagy. In addition, inhibition of autophagy by 3-methyladenine (3-MA) partially suppressed cytotoxicity induced by inhibition of Hh signaling. Finally, in autophagy deficient cells, cytotoxic effect triggered by inhibition of Hh signaling was partially reversed, indicating the modulation of autophagy by Hh signaling is autophagy-specific. These results suggest that inhibition of Hh signaling impedes cancer cell proliferation in part through induction of autophagy.

Topics: Adenine; Autophagy; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Hedgehog Proteins; Humans; Kruppel-Like Transcription Factors; Neoplasms; Nuclear Proteins; Pyridines; Pyrimidines; Signal Transduction; Transcriptome; Zinc Finger Protein Gli2

Cancer-related death is one of the most common causes of mortality in society. Small molecules have the capability to disrupt aberrant signaling pathways in tumors, leading to anticancer activities. Therefore the search for new molecules for cancer treatment continues to draw attention to the scientific research community. Synthesis and biological evaluation of hedgehog (Hh) pathway inhibitors SANT-1 and GANT-61 are disclosed. These molecules have been synthesized from common precursors using simple conversions, our synthesis features Vils-Meier-Haack reaction, imine formation reaction and N-arylation reaction. These drugs were evaluated using a Hh reporter assay to confirm pathway inhibitory activity, and tested for cell viability against pancreatic and prostate cancer cells. These methodologies can be applied to make potent analogs of both inhibitors.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Drug Discovery; Enzyme Inhibitors; Hedgehog Proteins; Humans; Male; Molecular Structure; Neoplasms; Piperazines; Pyrazoles; Pyridines; Pyrimidines; Signal Transduction