Browsing by Author "Atabey, Nese"

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Citation - WoS: 14
Citation - Scopus: 14
Effect of Adipocyte-Secreted Factors on Epcam+/Cd133+hepatic Stem Cell Population
(Academic Press Inc Elsevier Science, 2016) Karagonlar, Zeynep Firtina; Koc, Dogukan; Sahin, Eren; Avci, Sanem Tercan; Yilmaz, Mustafa; Atabey, Nese; Erdal, Esra
Recent epidemiological studies have associated obesity with a variety of cancer types including HCC. However, the tumor initiating role of obesity in hepatocarcinogenesis is still unknown. The objective of this paper is to investigate the effect of adipocyte-secreted factors on EpCAM+/CD133+ cancer stern cells and to identify which factors play a role in modulating hepatic cancer stem cell behavior. Our results demonstrated that adipocyte-secreted factors affect motility and drug resistance of EpCAM+/CD133+ cells. When incubated with adipocyte conditioned media, EpCAM-F/CD133+ cells exhibited augmented motility and reduced sorafenib-induced apoptosis. Using array-based system, we identified secretion of several cytokines such as IL6, IL8 and MCP1 by cultured adipocytes and activation of c-Met, STAT3 and ERK1/2 signaling pathways in EpCAM-F/CD133+ cells incubated with adipocyte conditioned media. Treating EpCAM+/CD133+ cancer stem cells with IL6 receptor blocking antibody or c-Met inhibitor SU11274 both reduced the increase in motility; however SU11274 had greater effect on relieving protection from sorafenib-induced apoptosis. These results indicate that adipocyte-secreted factors might regulate cancer stem cell behavior through several signaling molecules including c-Met, STAT3 and ERK1/2 and inhibition of these signaling pathways offer novel strategies in targeting the effect of adipose derived cytokines in cancer. (C) 2016 Elsevier Inc. All rights reserved.
Citation - WoS: 78
Citation - Scopus: 109
Elevated Hepatocyte Growth Factor Expression as an Autocrine C-Met Activation Mechanism in Acquired Resistance To Sorafenib in Hepatocellular Carcinoma Cells
(Wiley, 2016) Karagonlar, Zeynep Firtina; Koc, Dogukan; Iscan, Evin; Erdal, Esra; Atabey, Nese
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the third leading cause of cancer-related deaths worldwide. Limitations in HCC treatment result due to poor prognosis and resistance against traditional radiotherapy and chemotherapies. The multikinase inhibitor sorafenib is the only FDA approved drug available for advanced HCC patients, and development of secondline treatment options for patients who cannot tolerate or develop resistance to sorafenib is an urgent medical need. In this study, we established sorafenib-resistant cells from Huh7 and Mahlavu cell lines by long-term sorafenib exposure. Sorafenib-resistant HCC cells acquired spindle-shape morphology, upregulated mesenchymal markers, and showed significant increase in both migration and invasion abilities compared to their parental counterparts. Moreover, after long-term sorafenib treatment, HCC cells showed induction of hepatocyte growth factor (HGF) synthesis and secretion along with increased levels of c-Met kinase and its active phosphorylated form, indicating autocrine activation of HGF/c-Met signaling. Importantly, the combined treatment of the resistant cells with c-Met kinase inhibitor SU11274 and HGF neutralizing antibody significantly reversed the increased invasion ability of the cells. The combined treatment also significantly augmented sorafenib-induced apoptosis, suggesting restoration of sorafenib sensitivity. These results describe, for the first time, compensatory upregulation of HGF synthesis leading to autocrine activation of HGF/c-Met signaling as a novel cellular strategy in the acquisition of sorafenib resistance. Therefore, we suggest that combinatorial therapeutic strategies with HGF and c-Met inhibitors comprise promising candidates for overcoming sorafenib resistance.
Citation - WoS: 24
Citation - Scopus: 22
Lgr5/R-spo1 Axis Promotes Stemness and Aggressive Phenotype in Hepatoblast-Like Hepatocellular Carcinoma Cell Lines
(Elsevier Science Inc, 2021) Akbari, Soheil; Kunter, Imge; Azbazdar, Yagmur; Ozhan, Gunes; Atabey, Nese; Karagonlar, Zeynep Firtina; Erdal, Esra
Leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5) is a newly defined stem cell marker in endoderm-derived organs such as the small intestine, colon and pancreas. Recently, LGR5 was demonstrated to be an important factor in liver regeneration and stem cell maintenance. Moreover, LGR5 expression is highly upregulated in various cancers including hepatocellular carcinoma. Herein, we demonstrate that LGR5 expression is specifically observed in certain subset of HCC cell lines with ?hepatoblast-like? appearance, characterized by the expression of liver fetal/progenitor markers. Notably, the activation of the canonical Wnt pathway significantly increases the expression of LGR5 in this subset of cell lines, whereas it does not cause any induction of LGR5 expression in mesenchymal like cell lines SNU-475 and SNU-449. Furthermore, we showed that treatment of the hepatoblast-like HCC cell lines HuH-7 and Hep3B with LGR5 ligand R-Spo1 significantly amplifies the induction of LGR5 expression, the phosphorylation of LRP6 and ?-catenin resulting in enhanced TCF/LEF activity either alone or in combination with Wnt3a. Consistently, the silencing of the LGR5 gene attenuates the co-stimulatory effect of R-Spo1/Wnt3a on TCF/LEF activity while overexpression of LGR5 enhances it. On the contrary, overexpression of LGR5 does not change TCF/LEF activity induced by R-Spo1/Wnt3a in mesenchymal-like HCC line, SNU-449. Importantly, LGR5-overexpressing cells have increased expression of several Wnt target genes and stemness-related genes including EpCAM and CK19 upon R-Spo1/Wnt3a treatment. LGR5-overexpressing cells also have increased spheroid forming, migration and invasion abilities and stimulation with R-Spo1/Wnt3a augments these abilities of LGR5-overexpressing cells. In addition, ectopic overexpression of LGR5 significantly increases cell proliferation rate independent of R-Spo1/Wnt3a stimulation. Moreover, in vitro tubulogenesis assay demonstrates that treatment with R-Spo1/Wnt3a enhances the sprouting of capillary tubules in only LGR5overexpressing cells. Finally, R-Spo1/Wnt3a significantly promotes dissemination of LGR5-overexpressing cells in vivo in a zebrafish xenograft model. Our study unravels a tumor-promoting role for LGR5 through activation of canonical Wnt/?-catenin signaling in the hepatoblast-like HCCs. In conclusion, our results suggest that LGR5/RSpo1/Wnt3a generates an axis that mediates the acquisition of aggressive phenotype specifically in hepatoblastlike subset of HCCs and might represent a valuable target for treatment of HCC tumors with aberrant activation of Wnt/?-catenin pathway.
Citation - WoS: 1
Citation - Scopus: 1
Toll-Interacting Protein May Affect Doxorubicin Resistance in Hepatocellular Carcinoma Cell Lines
(Springer, 2023) Demir, Ayşe Banu; Barış, Elif; Kaner, Umay Bengi; Alotaibi, Hani; Atabey, Nese; Koc, Ahmet
BackgroundLiver cancer is the third leading cause of cancer-related deaths worldwide, and hepatocellular carcinoma (HCC) is the most common type of liver cancer. Transarterial interventions are among the chemotherapeutic approaches used in hardly operable regions prior to transplantation, and in electrochemotherapy, where doxorubicin is used. However, the efficacy of treatment is affected by resistance mechanisms. Previously, we showed that overexpression of the CUE5 gene results in doxorubicin resistance in Saccharomyces cerevisiae (S. cerevisiae). In this study, the effect of Toll-interacting protein (TOLLIP), the human ortholog of CUE5, on doxorubicin resistance was evaluated in HCC cells to identify its possible role in increasing the efficacy of transarterial interventions.Methods and resultsThe NIH Gene Expression Omnibus (GEO) and Oncomine datasets were analyzed for HCC cell lines with relatively low and high TOLLIP expression, and SNU449 and Hep3B cell lines were chosen, respectively. TOLLIP expression was increased by plasmid transfection and decreased by TOLLIP-siRNA in both cell lines and evaluated by RT-PCR and ELISA. Cell proliferation and viability were examined using xCELLigence and MTT assays after doxorubicin treatment, and growth inhibitory 50 (GI 50) concentrations were evaluated. Doxorubicin GI 50 concentrations decreased approximately 2-folds in both cell lines upon silencing TOLLIP after 48 h of drug treatment.ConclusionsOur results showed for the first time that silencing TOLLIP in hepatocellular carcinoma cells may help sensitize these cells to doxorubicin and increase the efficacy of chemotherapeutic regimens where doxorubicin is used.