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Author: search.filters.author.Kan, BekiHas files: No

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    Prognostic role of sensitive-to-apoptosis gene expression in rectal cancer
    (BAISHIDENG PUBL GRP CO LTD, 2011-01-01) Ozden, Sevgi A.; Ozyurt, Hazan; Ozgen, Zerrin; Kilinc, Olca; Oncel, Mustafa; Gul, Aylin E.; Karadayi, Nimet; Serakinci, Nedime; Kan, Beki; Orun, Oya
    AIM: To investigate the association between prognosis of rectal cancer treated with chemoradiotherapy (CRT) and expression of sensitive-to-apoptosis (SAG), B-cell lymphoma-extra large (Bcl-XL) and Bcl-2 homologous antagonist/killer (Bak). METHODS: Real-time quantitative polymerase chain reaction was used to determine the expression of proteins of interest, namely SAG, Bcl-XL, Bak and beta-actin, in rectal carcinoma patients who had a follow-up period of 3 years after CRT. Biopsy specimens were excised from the rectal tumor preceding CRT. RESULTS: SAG, Bcl-XL and Bak proteins showed significant correlations with each other. In multivariate analysis, patients with high vs low SAG expression showed a statistically significant difference in 2-year survival rates: 56\% vs 73\%, respectively (P = 0.056). On the other hand, there were no significant correlations between the expression levels of all three genes and metastatic rates or tumor responses to CRT. Mean overall survival in the patients with elevated SAG expression was 27.1 mo +/- 3.9 mo {[}95\% confidence interval (CI): 19.3-34.9], and in patients with reduced expression, it was 32.1 mo +/- 2.5 mo (95\% CI: 27.3-36.9). The corresponding values for Bcl-XL were 28.0 mo +/- 4.1 mo (95\% CI: 19.9-36.1) and 31.7 mo +/- 2.9 mo (95\% CI: 26.0-37.5), and those for Bak were 29.8 mo +/- 3.7 mo (95\% CI: 22.5-37.2) and 30.6 mo +/- 2.4 mo (95\% CI: 25.5-35.0), respectively. CONCLUSION: Two-year survival rates significantly correlated with low SAG expression, and SAG may be a candidate gene for good prognosis, independent of therapeutic response of different individuals. (C) 2011 Baishideng. All rights reserved.
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    Structural characterization of recombinant bovine Go alpha by spectroscopy and homology modeling
    (IOS PRESS, 2011-01-01) Tiber, Pinar Mega; Orun, Oya; Nacar, Cevdet; Sezerman, Ugur Osman; Severcan, Feride; Severcan, Mete; Matagne, Andre; Kan, Beki
    Go, a member of heterotrimeric guanine nucleotide-binding proteins, is the most abundant form of G protein in the central and peripheral nervous systems. Go alpha has a significant role in neuronal development and function but its signal transduction mechanism remains to be clarified. In this study, the bovine Go alpha subunit was overexpressed and purified into homogeneity. Its activity was studied using {[}S-35] GTP gamma S binding, intrinsic fluorescence and BODIPY assays. The secondary structure was determined by both FTIR and CD spectroscopy as 42.3\% alpha-helix, 13.4\% beta-sheet and 24.3\% beta-turn. A theoretical structure model was constructed. The structure from homology modeling is in very good agreement with the crystal structure of mouse Go alpha subunit except for the loop between alpha B-alpha C helices. This model was docked to the mouse RGS16 molecule. T117 on the alpha B-alpha C loop of Go alpha interacted with K172 on RGS16 as opposed to the T117 and K164 interaction in mouse.