Browsing by Author "Solak, Mustafa"

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Differential Expression of Stem Cell Markers and ABCG2 in Recurrent Prostate Cancer
(Wiley-Blackwell, 2014) Guzel, Esra; Karatas, Omer F.; Duz, Mehmet B.; Solak, Mustafa; Ittmann, Michael; Ozen, Mustafa
BACKGROUND. Prostate cancer (PCa) is the second most common tumor type related to mortality in males in the developed countries. Studies have demonstrated that therapeutic tools mostly ineffective to give positive outcome especially for PCa. Cancer stem cells are composed of a small cell population, which are supposed to have roles in tumorigenesis, metastasis, and tumor recurrence after chemo-radiotherapy. The aim of this research is to investigate expressions of stem cell markers in recurrent PCa and non-recurrent PCa tumors as well as in adjacent normal prostate tissues. METHODS. We compared the expression of important sternness regulators like SOX2, OCT4, KLF4, and ABCG2 in recurrent, non-recurrent PCa and adjacent normal tissue samples using quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS. Our results demonstrated that SOX2 and OCT4 are strongly overexpressed in PCa samples. Recurrent PCa samples are markedly positive for stem cell markers SOX2, OCT4, and KLF4. Furthermore, non-recurrent PCa samples presented low levels of ABCG2, a multidrug resistance protein, compared to both normal and recurrent samples, which might be associated with chemo-sensitivity. CONCLUSIONS. Enhanced expression of ABCG2 and stem cell markers including SOX2, OCT4, and KLF4 in the recurrent PCa tissues postulates the suggestion that enrichment for cells with stem cell characteristics in these tissues might be playing a critical role for chemoresistance and recurrence of cancer. (C) 2014 Wiley Periodicals, Inc.
Role of miR145 in Human Laryngeal Squamous Cell Carcinoma
(Wiley, 2016) Karatas, Omer Faruk; Yuceturk, Betul; Suer, Ilknur; Yilmaz, Mehmet; Cansiz, Harun; Solak, Mustafa; Ozen, Mustafa
BackgroundLaryngeal squamous cell carcinoma (SCC), being an aggressive malignancy, is one of the most commonly diagnosed malignant types of head and neck SCC worldwide. Incidences of laryngeal SCC have been reported to increase recently. In this study, we aimed to explore the biological effects of miR-145 on laryngeal cancer cells. MethodsThe relative miR-145 level in laryngeal SCC tumor tissues and normal samples was investigated. Then, Hep-2 cells were utilized for functional analysis of miR-145. The proliferation abilities of transfected cells were measured using MTS assay. Scratch assay and single colony migration assay were performed to observe the alterations in migration behavior of transfected cells. Caspase assay and cell cycle analysis were used to investigate the underlying reasons of proliferative inhibition in cells in which miR-145 is overexpressed. Moreover, expression of SOX2 was analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot analysis in Hep-2 cells upon miR-145 transfection and its expression was evaluated in tumor and normal tissue sample of the larynx. ResultsThe miR-145 expression in laryngeal SCC tumor samples has been shown to be downregulated. The miR-145 overexpression caused inhibition of proliferation and migration in Hep-2 cells through induction of apoptosis and cell cycle arrest. The SOX2 level was demonstrated to be overexpressed in tumor samples and its expression was significantly decreased in miR-145 overexpressed Hep-2 cells. ConclusionWe have demonstrated the deregulation of miR-145 and SOX2 in laryngeal SCC. Based on these results, we propose that miR-145, as an important regulator of SOX2, carries crucial roles in laryngeal SCC tumorigenesis. (c) 2015 Wiley Periodicals, Inc. Head Neck 38: 260-266, 2016