Titel Deelnemers "Korte inhoud" "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" "Alessia Parascandolo, Mikko O Laukkanen, Nancy De Rosa, Clara Ugolini, Maria Carmela Cantisani, Anna Maria Cirafici, Fulvio Basolo, Massimo Santoro, Maria Domenica Castellone" "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." "Targeting the Hedgehog pathway in combination with X‑ray or carbon ion radiation decreases migration of MCF‑7 breast cancer cells" "Katrien Konings, Niels BELMANS, Randy Vermeesen, Bjorn Baselet, Greta Lamers, Ann Janssen, Sofie Isebaert, Sarah Baatout, Karin Haustermans, Marjan MOREELS" "The use of carbon ion therapy for cancer treatment is becoming more widespread due to the advantages of carbon ions compared with X-rays. Breast cancer patients may benefit from these advantages, as the surrounding healthy tissues receive a lower dose, and the increased biological effectiveness of carbon ions can better control radioresistant cancer cells. Accumulating evidence indicates that the Hedgehog (Hh) pathway is linked to the development and progression of breast cancer, as well as to resistance to X-irradiation and the migratory capacity of cancer cells. Hence, there is an increasing interest in targeting the Hh pathway in combination with radiotherapy. Several studies have already investigated this treatment strategy with conventional radiotherapy. However, to the best of our knowledge, the combination of Hh inhibitors with particle therapy has not yet been explored. The aim of the present study was to investigate the potential of the Hh inhibitor GANT61 as an effective modulator of radiosensitivity and migration potential in MCF-7 breast cancer cells, and compare potential differences between carbon ion irradiation and X-ray exposure. Although Hh targeting was not able to radiosensitise cells to any radiation type used, the combination of GANT61 with X-rays or carbon ions (energy: 95 MeV/n; linear energy transfer: 73 keV/mu m) was more effective in decreasing MCF-7 cell migration compared with either radiation type alone. Gene expression of the Hh pathway was affected to different degrees in response to X-ray and carbon ion irradiation, as well as in response to the combination of GANT61 with irradiation. In conclusion, combining Hh inhibition with radiation (X-rays or carbon ions) more effectively decreased breast cancer cell migration compared with radiation treatment alone." "Depletion of the Colonic Epithelial Precursor Cell Compartment Upon Conditional Activation of the Hedgehog Pathway" "Guy Boeckxstaens" "Background & Aims: The intestinal epithelium is a homeostatic system in which differentiated cells are in dynamic equilibrium with rapidly cycling precursor cells. Wnt signaling regulates intestinal epithelial precursor cell fate and proliferation. Homeostatic systems exist by virtue of negative feedback loops, and we have previously identified the Hedgehog (Hh) pathway as a potential negative feedback signal in the colonic epithelium. Indian hedgehog (Ihh) is produced by the differentiated enterocytes and negatively regulates Wnt signaling in intestinal precursor cells. We studied the role of members of the Hh signaling family in the intestine using a conditional genetic approach. Methods: We inactivated the Hh receptor Patched1 (Ptch1) in adult mice, resulting in constitutive activation of the Hh signaling pathway. Effects on colonic mucosal homeostasis were examined. Colon tissues were examined by immunohistochemistry, in situ hybridization, transmission electron microscopy, and real-time polymerase chain reaction. Results: Ihh but not Sonic hedgehog (Shh) was expressed in colonic epithelium. Expression of Ptch1 and Gli1 was restricted to the mesenchyme. Constitutive activation of Hh signaling resulted in accumulation of myofibroblasts and colonic crypt hypoplasia. A reduction in the number of epithelial precursor cells was observed with premature development into the enterocyte lineage and inhibition of Writ signaling. Activation of Hh signaling resulted in induction of the expression of bone morphogenetic proteins (Bmp) and increased Bmp signaling in the epithelium. Conclusions: Hh signaling acts in a negative feedback loop from differentiated cells via the mesenchyme to the colonic epithelial precursor cell compartment in the adult mouse." "Targeting the Hedgehog signaling pathway in cancer: beyond Smoothened" "Annelies Gonnissen, Sofie Isebaert, Karin Haustermans" "An essential role for Hedgehog (Hh) signaling in human cancer has been established beyond doubt. At present, targeting Hh signaling has mainly been investigated with SMO inhibitors. Unfortunately, resistance against currently used SMO inhibitors has already been observed in basal cell carcinoma (BCC) patients. Therefore, the use of Hh inhibitors targeting the signaling cascade more downstream of SMO could represent a more promising strategy. Furthermore, besides the classical canonical way of Hh signaling activation, non-canonical activation of the GLI transcription factors by multiple important signaling pathways (e.g. MAPK, PI3K, TGFβ) has also been described, pinpointing the importance of targeting the transcription factors GLI1/2. The most promising agent in this context is probably the GLI1/2 inhibitor GANT61 which has been investigated preclinically in numerous tumor types in the last few years. In this review, the emerging role of Hh signaling in cancer is critically evaluated focusing on the potential of targeting Hh signaling more downstream of SMO, i.e. at the level of the GLI transcription factors. Furthermore, the working mechanism and therapeutic potential of the most extensively studied GLI inhibitor in human cancer, i.e. GANT61, is discussed in detail. In conclusion, GANT61 appears to be highly effective against human cancer cells and in xenograft mouse models, targeting almost all of the classical hallmarks of cancer and could hence represent a promising treatment option for human cancer." "Final analysis of phase II results with cemiplimab in metastatic basal cell carcinoma after hedgehog pathway inhibitors." "Oliver Bechter" "BACKGROUND: Metastatic basal cell carcinoma (mBCC) is a rare condition with no effective second-line treatment options. Cemiplimab is an immune checkpoint inhibitor that blocks the binding of programmed cell death-1 (PD-1) to its ligands, programmed death-ligand 1 (PD-L1) and programmed death-ligand 2 (PD-L2). Here, we present the final analysis of cemiplimab in patients with mBCC after first-line hedgehog pathway inhibitor (HHI) treatment (NCT03132636). PATIENTS AND METHODS: In this open-label, single-arm, phase II study, adults with mBCC and Eastern Cooperative Oncology Group performance status ≤1, post-HHI treatment, received cemiplimab 350 mg intravenously every 3 weeks for ≤93 weeks or until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by independent central review (ICR). Duration of response (DOR) was a key secondary endpoint. Other secondary endpoints were ORR per investigator assessment, progression-free survival (PFS), overall survival (OS), complete response rate, safety, and tolerability. RESULTS: Fifty-four patients were enrolled: 70% were male and the median age of patients was 64 [interquartile range (IQR) 57.0-73.0] years. The median duration of follow-up was 8 months (IQR 4-21 months). The ORR per ICR was 22% [95% confidence interval (CI) 12% to 36%], with 2 complete responses and 10 partial responses. Among responders, the median time to response per ICR was 3 months (IQR 2-7 months). The estimated median DOR per ICR was not reached [95% CI 10 months-not evaluable (NE)]. The disease control rate was 63% (95% CI 49% to 76%) per ICR and 70% (95% CI 56% to 82%) per investigator assessment. The median PFS per ICR was 10 months (95% CI 4-16 months); the median OS was 50 months (95% CI 28 months-NE). The most common treatment-emergent adverse events were fatigue [23 (43%)] and diarrhoea [20 (37%)]. There were no treatment-related deaths. CONCLUSIONS: Cemiplimab demonstrated clinically meaningful antitumour activity, including durable responses, and an acceptable safety profile in patients with mBCC who had disease progression on or intolerance to HHI therapy." "Hedgehog pathway activation in T-cell acute lymphoblastic leukemia predicts response to SMO and GLI1 inhibitors" "Antonis Dagklis, Sofie Demeyer, Jolien De Bie, Enrico Radaelli, Daphnie Pauwels, Sandrine Degryse, Olga Gielen, Carmen Vicente, Roel Vandepoel, Ellen Geerdens, Anne Uyttebroeck, Nancy Boeckx, Charles E de Bock, Jan Cools" "Hedgehog pathway mutations in T-cell acute lymphoblastic leukemia" "Ellen Geerdens, Barbara Cauwelier, Thomas Tousseyn, Anne Uyttebroeck, Johan Maertens, Gregor Verhoef, Peter Vandenberghe, Jan Cools" - "ECTOPIC EXPRESSION OF THE HEDGEHOG PATHWAY LIGANDS SHH AND IHH IN T-CELL ACUTE LYMPHOBLASTIC LEUKEMIA (T-ALL)" "Jan Cools" "Antagonistic cross-regulation between Wnt and Hedgehog signalling pathways controls post-embryonic retinal proliferation" "Caroline Borday, Pauline Cabochette, Karine Parain, Nicolas Mazurier, Sylvie Janssens, Hong Tran Thi, Belaïd Sekkali, Odile Bronchain, Kris Vleminckx, Morgane Locker, Muriel Perron" "The Notch intracellular domain integrates signals from Wnt, Hedgehog, TGFβ/BMP and hypoxia pathways" "An Zwijsen, Danny Huylebroeck" "Notch signaling is a highly conserved signal transduction pathway that regulates stem cell maintenance and differentiation in several organ systems. Upon activation, the Notch receptor is proteolytically processed, its intracellular domain (NICD) translocates into the nucleus and activates expression of target genes. Output, strength and duration of the signal are tightly regulated by post-translational modifications. Here we review the intracellular post-translational regulation of Notch that fine-tunes the outcome of the Notch response. We also describe how crosstalk with other conserved signaling pathways like the Wnt, Hedgehog, hypoxia and TGFβ/BMP pathways can affect Notch signaling output. This regulation can happen by regulation of ligand, receptor or transcription factor expression, regulation of protein stability of intracellular key components, usage of the same cofactors or coregulation of the same key target genes. Since carcinogenesis is often dependent on at least two of these pathways, a better understanding of their molecular crosstalk is pivotal."