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Öğe Cancer stem cell differentiation: TGF beta 1 and versican may trigger molecules for the organization of tumor spheroids(Spandidos Publ Ltd, 2014) Oktem, G.; Sercan, O.; Guven, U.; Uslu, R.; Uysal, A.; Goksel, G.; Ayla, S.; Bilir, A.Cancer stem cells (CSCs) have the ability to self-renew similar to normal stem cells. This process is linked with metastasis and resistance to chemotherapy and radiotherapy. In the present study, we constructed an in vitro differentiation model for CSCs. CSCs isolated and proliferated for one passage were maintained as monolayers or spheroid-forming cells with serum included media for differentiation process. Differentiation of adhesion molecules and cellular ultrastructural properties were investigated and compared in both monolayer and spheroid cultures. CD133(+)/CD44(+) cancer-initiating cells were isolated from DU-145 human prostate cancer cell line monolayer cultures and propagated as tumor spheroids and compared with the remaining heterogeneous cancer cell bulk population. Microarray-based gene expression analysis was applied to determine genes with differential expression and protein expression levels of candidates were analyzed by immunohistochemistry. Electron microscopy showed detailed analysis of morphology. TGF beta 1 was found to be significantly upregulated in monolayer CSCs. High expression levels of VCAN, COL7A1, 1TG beta 3, MMP16, RPL13A, COL4A2 and TIMP1 and low expression levels of THBS1, MMP1 and MMP14 were detected when CSCs were maintained as serum-grown prostate CSC spheroids. Immunohistochemistry supported increased immunoreactivity of TG beta 1 in monolayer cultures and VCAN in spheroids. CSCs were found to possess multipotential differentiation capabilities through upregulation and/or downregulation of their markers. TGF beta 1 is a triggering molecule, it stimulates versican, Co17A1, ITG beta 3 and, most importantly, the upregulation of versican was only detected in CSCs. Our data support a model where CSCs must be engaged by one or more signaling cascades to differentiate and initiate tumor formation. This mechanism occurs with intracellular and extracellular signals and it is possible that CSCc themselves may be a source for extracellular signaling. These molecules functioning in tumor progression and differentiation may help develop targeted therapy.Öğe Chemotherapy influences inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) activity on 3D breast cancer cell line(Cognizant Communication Corp, 2006) Oktem, G.; Bilir, A.; Selvi, N.; Yurtseven, M. E.; Vatansever, S.; Ates, U.; Uysal, A.; Omay, S. B.Multicellular tumor spheroids (NITS) are three-dimensional structural forms of tumors grown in vitro in the laboratory. In this study, the aim was to determine the regulation of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) expressions on NITS in response to treatment with the commonly used anti-cancer drugs Doxorubicin and Docetaxel. The spheroids were generated using the "liquid overlay" technique. The distribution of both iNOS and eNOS was detected using indirect immunohistochemistry, while the expression of both iNOS and eNOS was measured using Western blots. Additionally, S-phase analysis using 5-bromo-2'-deoxyuridine (BrdU) was done on the MTS after treatment with doxorubicin, docetaxel, and a combination of the two. The Griess method was used to measure nitric oxide (NO) production in the cells. An increase in iNOS immunoreactivity and a decrease in eNOS immunoreactivity were observed after doxorubicin treatment, when compared with the other groups. Furthermore, upregulation of iNOS and downregulation of eNOS were detected in doxorubicin-treated cells using Western blotting. Insignificant iNOS expression was observed in all of the groups, and it was particularly low in the control and drug combination groups. NO production was also found to be significantly high after docetaxel treatment, and cell proliferation decreased after doxorubicin treatment. In conclusion, chemotherapy influences NOS activity differently with the presence of different drugs. The results with iNOS show that doxorubicin is a more effective drug than docetaxel, and a drug combination may play a helpful role in the suppression of tumorigenicity and cancer metastasis. Interestingly, eNOS expression increased after the addition of both docetaxel and the drug combination, and it was found to negatively correlate with the histological grade of the tumor. Therefore, analyzing the expression of both iNOS and eNOS might be very useful for targeting the treatment of breast carcinoma and obtaining better information on prognosis.Öğe Hepatic progenitor cell inhibition during embryonic period with high dose verapamil, liable joint to the cancer therapy(Comenius Univ, 2013) Uslu, S.; Uysal, A.; Bilir, A.; Soner, B. C.; Oktem, G.Cancer stem cells (CSCs) have been observed to share certain characteristics with normal stem cells. It was an important argument for cancer therapy and a successful progenitor inhibition could show us targeted cell type for a novel strategy. In this study, we aimed to constitute an inhibition in different stages of hepatic stem/progenitor cells (HPCs) with verapamil. Expression patterns of alpha-fetoprotein (AFP), c-kit (CD117) and p-glycoprotein were investigated in developing mouse on the embryonic day (E) 15, E18 and E21 to characterize early and late stages of HPCs. Proliferation inhibition with 5-Bromo-2-Deoxyuridin (BrdU) incorporation and maturation inhibition with PAS staining results were supported by morphometrical analysis during these periods. AFP, c-kit and p-glycoprotein immunoreactivity increased especially in E15 but decreased in E18 and E21 of the control groups during embryonic development. Verapamil treatment effected particularly E15 cells and immunoexpression of HPCs significantly decreased. Proliferation inhibition was observed in all embryonic days of mouse with verapamil and this drug inhibited not only maturation of HPCs in E18 and E21 embryos, but also decreased HPC number in the same embryonic period. According to our results, we estimated that similar to the early and late progenitor stages of HPCs, CSCc can also be in different stages in a heterogenic tumour bulk and the difficulty of CSC inhibition could be the main mechanism of tumour relapses. In this study, HPCs inhibition by verapamil in E15 was not observed in E18 and E21. As similar, CSCs treatments targeting different stages may be impotent to cells in tumour initiating cell stage. We can speculate that ineffectiveness of CSC-specific therapies may be attributed to the highly selective specificity of the treatment (Fig. 6, Ref. 28). Full Text in PDF www.elis.sk.Öğe Lithium for treatment and chemo-sensitization: Testing the hypothesis on SH-SY5Y cells in monolaver and 3D-spheroids(Academic Press Inc Elsevier Science, 2007) Oktem, G.; Bilir, A.; Erguven, M.; Altinoz, M.; Yazihan, N.; Kose, T.Öğe Role of intercellular communications in breast cancer multicellular tumor spheroids after chemotherapy(Cognizant Communication Corp, 2006) Oktem, G.; Bilir, A.; Ayla, S.; Yavasoglu, A.; Goksel, G.; Saydam, G.; Uysal, A.Tumor heterogeneity is an important feature that is especially involved in tumor aggressiveness. Multicellular tumor spheroids (MTS) may provide some benefits in different steps for investigation of the aggregation, organization, differentiation, and network formation of tumor cells in 3D space. This model offers a unique opportunity for improvements in the capability of a current strategy to detect the effect of an appropriate anticancer agent. The aim of this study was to investigate the cellular interactions and morphological changes following chemotherapy in a 3D breast cancer spheroid model. Distribution of the gap junction protein "connexin-43" and the tight junction protein "occludin" was investigated by immunohistochemistry. Cellular interactions were examined by using transmission and scanning electron microscopies as well as light microscopy with Giemsa staining after treating cells with doxorubicin, docetaxel, and doxorubicin/docetaxel combination. Statistical analyses showed significant changes and various alterations that were observed in all groups; however, the most prominent effect was detected in the doxorubicin/docetaxel combination group. Distinct composition as a vessel-like structure and a pseudoglandular pattern of control spheroids were detected in drug-administered groups. Immunohistochemical results were consistent with the ultrastructural changes. In conclusion, doxorubicin/docetaxel combination may be more effective than the single drug usage as shown in a 3D model. The MTS model has been found to be an appropriate and reliable method for the detection of the changes in the expression of cellular junction proteins as well as other cellular proteins occurring after chemotherapy. The MTS model can be used to validate the effects of various combinations or new chemotherapeutic agents as well as documentation of possible mechanisms of new drugs.
