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Permanent URI for this collectionhttps://hdl.handle.net/11443/932

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Author: search.filters.author.Ceyhan, Guralp Onur

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    Indirect cholinergic activation slows down pancreatic cancer growth and tumor-associated inflammation
    (BMC, 2020-01-01) Pfitzinger, Paulo L.; Fangmann, Laura; Wang, Kun; Demir, Elke; Guerlevik, Engin; Fleischmann-Mundt, Bettina; Brooks, Jennifer; D'Haese, Jan G.; Teller, Steffen; Hecker, Andreas; Jesinghaus, Moritz; Jaeger, Carsten; Ren, Lei; Istvanffy, Rouzanna; Kuehnel, Florian; Friess, Helmut; Ceyhan, Guralp Onur; Demir, Ihsan Ekin
    Background Nerve-cancer interactions are increasingly recognized to be of paramount importance for the emergence and progression of pancreatic cancer (PCa). Here, we investigated the role of indirect cholinergic activation on PCa progression through inhibition of acetylcholinesterase (AChE) via clinically available AChE-inhibitors, i.e. physostigmine and pyridostigmine. Methods We applied immunohistochemistry, immunoblotting, MTT-viability, invasion, flow-cytometric-cell-cycle-assays, phospho-kinase arrays, multiplex ELISA and xenografted mice to assess the impact of AChE inhibition on PCa cell growth and invasiveness, and tumor-associated inflammation. Survival analyses were performed in a novel genetically-induced, surgically-resectable mouse model of PCa under adjuvant treatment with gemcitabine+/-physostigmine/pyridostigmine (n = 30 mice). Human PCa specimens (n = 39) were analyzed for the impact of cancer AChE expression on tumor stage and survival. Results We discovered a strong expression of AChE in cancer cells of human PCa specimens. Inhibition of this cancer-cell-intrinsic AChE via pyridostigmine and physostigmine, or administration of acetylcholine (ACh), diminished PCa cell viability and invasion in vitro and in vivo via suppression of pERK signaling, and reduced tumor-associated macrophage (TAM) infiltration and serum pro-inflammatory cytokine levels. In the novel genetically-induced, surgically-resectable PCa mouse model, adjuvant co-therapy with AChE blockers had no impact on survival. Accordingly, survival of resected PCa patients did not differ based on tumor AChE expression levels. Patients with higher-stage PCa also exhibited loss of the ACh-synthesizing enzyme, choline-acetyltransferase (ChAT), in their nerves. Conclusion For future clinical trials of PCa, direct cholinergic stimulation of the muscarinic signaling, rather than indirect activation via AChE blockade, may be a more effective strategy.
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    Targeting the undruggable oncogenic KRAS: the dawn of hope
    (AMER SOC CLINICAL INVESTIGATION INC, 2022-01-01) Asimgil, Hande; Ertetik, Utku; Cevik, Nedim Can; Ekizce, Menar; Dogruoez, Alper; Goekalp, Muazzez; Arik-Sever, Elif; Istvanffy, Rouzanna; Friess, Helmut; Ceyhan, Guralp Onur; Demir, Ihsan Ekin
    KRAS mutations are the drivers of various cancers, including non-small cell lung cancer, colon cancer, and pancreatic cancer. Over the last 30 years, immense efforts have been made to inhibit KRAS mutants and oncogenic KRAS signaling using inhibitors. Recently, specific targeting of KRAS mutants with small molecules revived the hopes for successful therapies for lung, pancreatic, and colorectal cancer patients. Moreover, advances in gene editing, protein engineering, and drug delivery formulations have revolutionized cancer therapy regimens. New therapies aim to improve immune surveillance and enhance antitumor immunity by precisely targeting cancer cells harboring oncogenic KRAS. Here, we review recent KRAS-targeting strategies, their therapeutic potential, and remaining challenges to overcome. We also highlight the potential synergistic effects of various combinatorial therapies in preclinical and clinical trials.
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    Genetic landscape of pancreatic cancer: a narrative review
    (AME PUBL CO, 2022-01-01) Yakar, Didem Oncel; Bozkirli, Bahadir Osman; Ceyhan, Guralp Onur
    Background and Objective: Pancreatic cancer is an aggressive disease with an impaired survival despite improvements in clinical management. Thus, understanding disease biology is of vital importance in order to overcome therapeutic challenges and achieve better prognosis. The purpose of this review is to outline the genetic landscape of pancreatic cancer along with its clinical implications. Methods: We reviewed existing literature using electronic databases to outline the genetic landscape in pancreatic cancer. Key Content and Findings: This review mainly contains information on the genetic background of pancreatic cancer, mainly KRAS, CDKN2A, TP53 and SMAD4, with emphasis on the importance of understanding disease biology. Conclusions: The genetic aspects of pancreatic cancer have been well described especially with the introduction of next generation sequencing techniques. Future studies focusing on translation of these alterations in clinical application might pave the way for personalized surveillance and therapy.
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    Optimizing the Personalized Care for the Management of Rectal Cancer: A Consensus Statement
    (AVES, 2022-01-01) Aytac, Erman; Ozer, Leyla; Baca, Bilgi; Balik, Emre; Kapran, Yersu; Taskin, Orhun Cig; Uluc, Basak Oyan; Abacioglu, Mehmet Ufuk; Gonenc, Murat; Bolukbasi, Yasemin; Cil, Barbaros E.; Baran, Bulent; Aygun, Cem; Yildiz, Mehmet Erdem; Unal, Kemal; Erkol, Burcak; Yalti, Tunc; Ozbek, Ugur; Attila, Tan; Tozun, Nurdan; Gurses, Bengi; Erdamar, Sibel; Er, Ozlem; Bese, Nuran; Bilge, Orhan; Ceyhan, Guralp Onur; Mandel, Nil Molinas; Selek, Ugur; Yakicier, Cengiz; Karabey, Hulya Kayserili; Saruc, Murat; Ozben, Volkan; Esen, Eren; Ozoran, Emre; Vardareli, Erkan; Guner, Levent; Hamzaoglu, Ismail; Bugra, Dursun; Karahasanoglu, Tayfun; Grp, Istanbul
    Colorectal cancer is the third most common cancer in Turkey. The current guidelines do not provide sufficient information to cover all aspects of the management of rectal cancer. Although treatment has been standardized in terms of the basic principles of neoadjuvant, surgical, and adjuvant therapy, uncertainties in the management of rectal cancer may lead to significant differences in clinical practice. In order to clarify these uncertainties, a consensus program was constructed with the participation of the physicians from the Acibadem Mehmet Ali Aydinlar and Koc Universities. This program included the physicians from the departments of general surgery, gastroenterology, pathology, radiology, nuclear medicine, medical oncology, radiation oncology, and medical genetics. The gray zones in the management of rectal cancer were determined by reviewing the evidence-based data and current guidelines before the meeting. Topics to be discussed consisted of diagnosis, staging, surgical treatment for the primary disease, use of neoadjuvant and adjuvant treatment, management of recurrent disease, screening, follow-up, and genetic counseling. All those topics were discussed under supervision of a presenter and a chair with active participation of related physicians. The consensus text was structured by centralizing the decisions based on the existing data.