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

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Author: search.filters.author.Obek, CanHas files: Yes

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    Non-muscle invasive bladder cancer tissues have increased base excision repair capacity
    (NATURE PORTFOLIO, 2020-01-01) Somuncu, Berna; Keskin, Selcuk; Antmen, Fatma Merve; Saglican, Yesim; Ekmekcioglu, Aysegul; Ertuzun, Tugce; Tuna, Mustafa Bilal; Obek, Can; Wilson, David M.; Ince, Umit; Kural, Ali Riza; Muftuoglu, Meltem
    The molecular mechanisms underlying the development and progression of bladder cancer (BC) are complex and have not been fully elucidated. Alterations in base excision repair (BER) capacity, one of several DNA repair mechanisms assigned to preserving genome integrity, have been reported to influence cancer susceptibility, recurrence, and progression, as well as responses to chemotherapy and radiotherapy. We report herein that non-muscle invasive BC (NMIBC) tissues exhibit increased uracil incision, abasic endonuclease and gap-filling activities, as well as total BER capacity in comparison to normal bladder tissue from the same patient (p<0.05). No significant difference was detected in 8-oxoG incision activity between cancer and normal tissues. NMIBC tissues have elevated protein levels of uracil DNA glycosylase, 8-oxoguanine DNA glycosylase, AP endonuclease 1 and DNA polymerase beta protein. Moreover, the fold increase in total BER and the individual BER enzyme activities were greater in high-grade tissues than in low-grade NMIBC tissues. These findings suggest that enhanced BER activity may play a role in the etiology of NMIBC and that BER proteins could serve as biomarkers in disease prognosis, progression or response to genotoxic therapeutics, such as Bacillus Calmette-Guerin.
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    Water Vapor Thermal Therapy (RezumTM) for Benign Prostate Hyperplasia: Initial Experience from Turkiye
    (GALENOS PUBL HOUSE, 2022-01-01) Tuna, Mustafa Bilal; Doganca, Tunkut; Argun, Omer Burak; Pirdal, Betul Zehra; Tufek, Ilter; Obek, Can; Kural, Ali Riza
    Objective: Rezumn{''} system is a safe minimal invasive treatment modality for benign prostate hyperplasia (BPH) treatment. The aim of this study was to evaluate the short-term results of Rezumn{''} therapy in our center.Materials and Methods: We retrospectively collected the data of 28 patients with symptomatic BPH who underwent RezumTM therapy in our center. All patients' pre-operative and post-operative
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    Magnetic Resonance - Transrectal Ultrasound Fusion Guided Prostate Biopsy
    (GALENOS YAYINCILIK, 2016-01-01) Argun, Omer Burak; Obek, Can; Kural, Ali Riza
    Prostate has remained as the single solid organ for which biopsy cannot be performed from a lesion for decades. Lately, the groundbreaking magnetic resonance imaging (MRI) techniques have emerged to scan prostate cancer and have become an important diagnostic tool in the diagnosis of prostate cancer. Efforts to improve the accuracy of the standard biopsy methods have led to the emergence of target-oriented biopsy methods. Today, MRI-transrectal ultrasound (TRUS) fusion guided biopsy methods are being used increasingly, especially for patients with an increasing prostate specific antigen level after a previous negative biopsy result and for patients under follow-up with active surveillance protocols. Even though it is not yet suggested in guidelines, our view and practice are in line with the fact that MRI-TRUS fusion guided biopsy is the most ideal biopsy method in any patient scheduled for a prostate biopsy with a significant lesion on MRI.
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    5-Hydroxyuracil Incision Activity Varies According to the Histological Grade of Non-muscle-invasive Bladder Cancer
    (GALENOS YAYINCILIK, 2021-01-01) Keskin, Selcuk; Antmen, Fatma Merve; Somuncu, Berna; Saglican, Yesim; Doganca, Tunkut; Obek, Can; Ince, Umit; Kural, Ali Riza; Muftuoglu, Meltem
    Objective: High levels of endonuclease III-like 1 (NTHL1) DNA glycosylase, which plays a role in the first step of the base excision repair pathway, has been related to cancer initiation and progression. 5-hydroxyuracil (5-OHU) oxidative base damage is a substrate for NTHL1 and endonuclease VIII-like 1 enzyme 1 (NEIL1) DNA glycosylases. This study investigates the association of 5-OHU incision activity with the risk of disease progression in patients with non-muscle-invasive bladder cancer (NMIBC) regarding grade and stage. Materials and Methods: During transurethral resection of 17 NMIBC patients, the papillary tumour before monopolar resection and healthy bladder mucosal tissue from the same person were obtained using cold cup biopsy. Both the normal mucosa and NMIBC tumour were pathologically confirmed. The histological grade and stage were also determined. The 5-OHU incision activity of all tissues was measured using a radiolabelled 5-OHU modified base containing DNA substrate. Results: 5-OHU incision activity was significantly higher in all high-grade NMIBC tissue extracts compared with the corresponding normal tissues (p=0.001). However, we found no significant difference in 5-OHU incision activity in low-grade NMIBC tissues (p=0.89). There was also a significant increase in 5-OHU incision activity at the Ta/T1 stage compared with the corresponding normal tissue (p=0.001). Conclusion: The increase in 5-OHU incision activity according to the histological grade of NMIBC tissue indicates that this activity (mainly performed by NTHL1 and NEIL1 DNA glycosylases) might play a role in NMIBC prognosis. Thus, it could be used as a potential prognostic biomarker for NMIBC.
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    Management of prostate cancer patients during COVID-19 pandemic
    (SPRINGERNATURE, 2020-01-01) Obek, Can; Doganca, Tunkut; Argun, Omer Burak; Kural, Ali Riza
    Prostate cancer patients' management demands prioritization, adjustments, and a tailored approach during the unprecedented SARS-CoV-2 pandemic. Benefit of care from treatment must be carefully weighed against the potential of infection and morbidity from COVID-19. Furthermore, urologists need to be cognizant of their obligation for wise consumption of restricted healthcare resources and protection of the safety of their coworkers. Nonurgent in-person clinic visits should be postponed or conducted remotely via phone or teleconference. Prostate cancer screening, imaging, and biopsies may be suspended in general. Treatment may be safely deferred in low and intermediate risk patients. Surgery may be delayed in most high-risk patients and neoadjuvant ADT is generally not advocated prior to surgery. Initiation of long-term ADT coupled with EBRT subsequent to the pandemic may be favored as a feasible alternative in high-risk and very high-risk disease. In patients with cN1 disease, treatment within 6 weeks is advocated. Presurgery assessment should include testing for COVID-19 and preferably a chest imaging. In the presence of SARS-CoV-2 infection, surgery should be postponed whenever possible. All protective measurements suggested by national/international authorities must to be diligently followed during perioperative period. Strict precautions specific to laparoscopic/robotic surgery are required, considering the unproven but potential risk of aerosolization of SARS-CoV-2 virus and spillage with pneumoperitoneum. Regarding radiotherapy, shortest safe EBRT regimen should be favored and prophylactic whole pelvic RT and brachytherapy avoided. Chemotherapy should be avoided whenever possible.