Browsing by Subject "CD133"

Now showing 1 - 2 of 2

Open Access
Characterization of cancer stem cells in hepatocellular carcinoma
(2014) Abdüsselamoğlu, Merve Deniz
Hepatocellular carcinoma (HCC) is the third most common cause of death from cancer worldwide due to the challenges in both its diagnosis and treatment. According to recent studies, HCC tumors, like many other solid tumors are initiated and maintained by a subpopulation of cells called “cancer stem cells (CSCs)” or "tumor-initiating cells (TICs)". HCC stem cells can be identified by the expression of cardinal CD markers such as CD133 (Prominin-1) and epithelial cell adhesion molecule (EpCAM). This study primarily focuses on the investigation of mechanisms involved in the generation of HCC stem cell sub-population using a panel of 15 HCC cell lines. Preliminary data indicates that four cell lines (27%) display CD133+ stem cell populations at frequencies ranging from 8 to 90% when tested by flow cytometry. Among these CD133 positive cell lines, two isogenic cell line with different positivity levels prompted us to focus on two specific cell lines;, i) parental HepG2 cell line and its clone, which was transfected with four copies of hepatitis B virus (HBV), namely ii) HepG2-2215. With tumorigenicity assay induced in atymic nude mice, data revealed that HepG2-2215 that had higher CD133+ ratio, showed higher and rapid tumor formation than parental HepG2 that had much lower CD133+ sub-cellular proportion. Microarray analyses were performed to underpin the mechanisms of in CD133+ cell number variations of these two cell lines. Our initial findings suggested that FGFR signaling pathway might have played a role. To investigate these findings, FGFR signaling pathway was inhibited via potent inhibitor as well as knock down with siRNA. However, preliminary data did not indicate these presumptions and further studies are needed to clarify the relationship between FGFR signaling and CSC formation in HCC. Also, role of suppressive oligodeoxynucleotide (ODN) was studied to see the effects of suppression of DNAdriven immunostimulation. Findings showed that suppressive ODN decreased CD133 levels, which indicates the difference between these two cell lines may arise from the HBV transfection of HepG2-2215 cell line which can produce HBV particles. However, further investigation is needed to understand the relationship between HBV infection and CSC population in HCC.
Open Access
Contribution of notch signaling on HCC stem cell status and utilizing TLR agonists and notch inhibition to improve HCC theraphy
(2014) Ertuna, Yusuf İsmail
Hepatocellular carcinoma (HCC) is the seventh most common cancer type worldwide, and ranked third place among cancer-related deaths within both sexes. As in many solid tumors, HCC shelters a cancer stem cell subpopulation, and is held responsible for the resistance developed during chemo-and-radio-therapy of HCC. The only option to cure HCC is liver transplantation, which is the bottleneck to provide a remedy to patients due to limited availability. Understanding the stem cell behavior of HCC would critically contribute to develop effective eradication strategies. In this study, a panel of 17 HCC cell lines was evaluated for their CSC status. Of these cell lines, six of them were determined to be positive for CD133 expression, a cardinal CSC marker. Next, HepG2, Huh7 and Hep3B-TR, (a desensitized TGF-beta-1 receptor clone) were selected and Notch activity vs. CSC fraction was investigated by analyzing CD133+/EpCAM+ levels. Our results revealed that DAPT (a notch inhibitor) led to a drop in CD133+/EpCAM+ levels in HepG2 and Huh7 by half, but not in Hep3B-TR cells, implicating a possible TGFβ1R involvement on CSC generation/maintenance. Treatment of cells with a notch ligand, Jagged-1, however, had little or no positive effect on CD133+/EpCAM+ expressions in all tested cells. Additionally, HCC cells' response to different TLR ligands and the resulting transcript expressions of TLRs were investigated by PCR. Of note, TLRs are widely used in immunotherapy of cancers. Here we aimed to combine Notch inhibitor along with selected TLR ligand, thereby improving tumor clearance in athymic mice xenografted with HCC. We found that in three selected cell lines upon TLR2 ligand stimulation, TLR5 and TLR7 were highly upregulated. Afterwards, treating these HCC cell lines with these ligands we observed that TLR3, TLR7/8 and TLR9 levels were activated. In the final part of this study, tumor-bearing mice with Huh7, were subjected to a combination therapy with TLR ligands +/- DAPT. We demonstrated that combination therapy comprising TLR3, 7/8 and 9 ligands and DAPT (only two injections, a week apart) induced significant tumor regression.