Important Role In Therapy Resistance Research Articles

11P - The role of downregulated SIRT3 expression in patients with hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is the fifth leading cause of cancer-related deaths worldwide. The only drug currently approved for clinical use in the treatment of advanced HCC is sorafenib, a tyrosine kinase inhibitor. However, many patients with HCC are resistant to sorafenib and sensitivity to sorafenib differs according to the progression of liver cancer. SIRT3, a member of the mammalian sirtuin family, is localized to the mitochondria and regulates metabolic activity. To date, a few studies have investigated the effects of SIRT3 on prognosis and drug resistance in patients with HCC. Methods: A correlation study between SIRT3 and other genes was conducted through the TCGA online data portal site (http://cancergenome.nih.gov). To determine the protein expression of SIRT3, immunohistochemistry (IHC) was performed with liver cancer tissue using various antibodies. To investigate whether the expression of SIRT3 in HCC is related to the resistance to sorafenib, we treated sorafenib after the modulation of SIRT3 levels in HCC cell lines (overexpression in Huh7, knockdown in HepG2 and Hep3B cells) and conducted functional assays. Results: We identified that SIRT3 expression is downregulated in patients with HCC and high GLUT1 (glucose metabolism index) and Ki67 (proliferation index) expression. In addition, analysis of Cancer Imaging Archive data (TCGA) revealed a negative correlation between GLUT1 and SIRT3 mRNA expression and also HIF1a and SIRT3 mRNA expression. There was also a negative correlation between Ki67 and SIRT3 mRNA expression. After sorafenib treatment, SIRT3 protein expression was highly downregulated in various HCC cell lines (HepG2/Hep3B/SK-Hep1/Huh7). These cells altered their therapeutic resistance to sorafenib via SIRT3 modulation through a 2 dimensional (D)/3D cell culture system. Conclusions: Taken together, our results show that SIRT3 acts as a tumor suppressor and plays an important role in therapy resistance for HCC. Legal entity responsible for the study: Misu Lee. Funding: The National Research Foundation of Korea (Seoul, Korea; Grant Nos. NRF-2015R1D1A1A01057737, NRF-2018R1C1B6003894). Disclosure: All authors have declared no conflicts of interest.

MTOR activity and its prognostic significance in human colorectal carcinoma depending on C1 and C2 complex-related protein expression

AimsTumour heterogeneity and altered activation of signalling pathways play important roles in therapy resistance. The PI3K/Akt/mTOR signalling network is a well-known regulator of several functions that contribute to tumour growth....

Cancer stem-like sphere cells induced from de-differentiated hepatocellular carcinoma-derived cell lines possess the resistance to anti-cancer drugs.

BackgroundCancer stem cells (CSCs) are thought to play important roles in therapy-resistance. In this study, we induced cancer stem-like cells from hepatocellular carcinoma (HCC) cell lines using a unique medium, and examined their potential for resistance to anti-cancer drugs.MethodsThe human HCC cell lines SK-HEP-1 (SK), HLE, Hep 3B, and HuH-7 were used to induce cancer stem-like cells with our sphere induction medium supplemented with neural survival factor-1. NANOG and LIN28A were examined as stemness markers. Several surface markers for CSC such as CD24, CD44, CD44 variant, and CD90 were analyzed by flow-cytometry. To assess the resistance to anti-cancer drugs, the MTS assay, cell cycle analysis, and reactive oxygen species (ROS) activity assay were performed.ResultsPoorly differentiated HCC derived SK and undifferentiated HCC derived HLE cell lines efficiently formed spheres of cells (SK-sphere and HLE-sphere), but well-differentiated HCC-derived HuH-7 and Hep 3B cells did not. SK-spheres showed increased NANOG, LIN28A, and ALDH1A1 mRNA levels compared to parental cells. We observed more CD44 variant-positive cells in SK-spheres than in parental cells. The cell viability of SK-spheres was significantly higher than that of SK cells in the presence of several anti-cancer drugs except sorafenib (1.7- to 7.3-fold, each P < 0.05). The cell cycle of SK-spheres was arrested at the G0/G1 phase compared to SK cells. SK-spheres showed higher ABCG2 and HIF1A mRNA expression and lower ROS production compared to parental cells.ConclusionOur novel method successfully induced cancer stem-like cells, which possessed chemoresistance that was related to the cell cycle, drug efflux, and ROS.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-722) contains supplementary material, which is available to authorized users.

Clinical significance and prognostic impact of CD133 expression in rectal cancer treated with preoperative radiochemotherapy.

e14161 Background: CD133 has been described as a potential stem cell marker in colorectal cancer and to be associated with higher tumorigenic potential and resistance to radiochemotherapy (RCT). In this study the expression of CD133 was evaluated in pre-RCT tumor biopsies and the corresponding post-RCT surgical specimens of locally advanced rectal cancer patients and correlated to histopathological features and clinical follow-up. Methods: 127 patients with UICC (Union contre le Cancer) II/III rectal cancer treated with preoperative 5-FU based RCT within the German Rectal Cancer Trials were investigated. Pre- and post-RCT CD133 expression levels were determined using immunhistochemistry and correlated with histopathologic parameters, tumor regression grade, cancer recurrence and survival. Results: As compared to pre-RCT biopsies we observed a significantly higher CD133 expression in tumor specimens (p=0.01). There was, however, no correlation for both biopsies and tumor specimens between CD133 expression levels, histopathological features and survival. In matched analyses of corresponding biopsy/tumor pairs, patients with a decreased fraction of CD133+ cells after preoperative RCT showed significantly lower residual tumor stages (p=0.03) and higher histopathological tumor regression (p&lt;0.01). Moreover, these patients had a significantly improved disease-free (DFS) and cancer-specific overall survival (CSS) in uni- (p&lt;0.001) and multivariate analyses (p=0.001), respective. Conclusions: Enrichment of CD133+ cancer cells during preoperative RCT is correlated with minor local tumor response, distant cancer recurrence and survival. Up-regulation of intratumoral CD133 expression – more than pre- and post-RCT CD133 levels – plays an important role in therapy resistance, tumor progression and metastasis in rectal cancers undergoing neoadjuvant RCT.

Abstract 693: Evaluating the role of CXCR2 receptor and its ligand in breast cancer therapy resistance

Abstract Breast cancer is the second leading cause of cancer deaths among women after lung cancer, accounting for more than 40,000 deaths each year. Although there has been advancement in the treatment and diagnosis of breast cancer, therapy resistance and relapse are still big hurdles in the way. Recent reports and our preliminary studies suggest that malignant cells that survive the initial chemo- and radiation therapy express higher levels of CXCR2 ligands which might provide a survival benefit to malignant tumors leading to therapy resistance. The specific objective for this study involves targeting CXCR2 receptor and its ligands mediated signaling for therapy resistance in mammary tumor cells. Our hypothesis is that CXCR2 along with its ligands plays an important role in therapy resistance and that targeting this signaling pathway will provide an effective strategy to overcome the problem. We used mammary tumor cells expressing different levels of CXCR2 (Cl66-wt and Cl66-shCXCR2) and examined their response to Paclitaxel and Doxorubicin. We observed significant enhancement of paclitaxel and doxorubicin-mediated toxicity at lower concentrations in Cl66-shCXCR2 cells as compared to Cl66-wt cells. Moreover, we observed an increase in the expression of CXCL1, a CXCR2 ligand, with increasing doses of drugs. However, paclitaxel and doxorubicin induced CXCL-1 levels was significantly lower in Cl66-shCXCR2 cells as compared to Cl66-wt cells. To further validate our findings we selected Cl66 against paclitaxel and doxorubicin resistant cells by treating with increasing doses of these drugs. Cells were maintained in 500nM doxorubicin and 400nM paclitaxel. We analyzed the sensitivity of these cells to doxorubicin and paclitaxel in comparison to wild type parent cells. We observed that resistant cells survive even at higher concentrations (higher than at which they are maintained) of drugs. Although, paclitaxel resistant cells appears to be sensitive at higher doses of paclitaxel when compared to doxorubicin resistant cells in the same set of experiments. Further studies showed an increase in the expression of CXCL1 in the supernatant of these cells after drug treatment. The expression of CXCL1 was higher even at the basal level in the resistant cells in comparison to the parent cells. As it has been shown that expression of CXCR2 ligands increase after chemotherapy, we examined the expression profile of various CXCR2 ligands in these cells at the mRNA level. We observed that these cells express higher levels of CXCL5, CXCL3 and CXCL7, in comparison to parent Cl66 cells. Together, these results demonstrate that i) CXCR2 and its ligand-mediated signaling plays an important role in the drug resistance of mammary tumors cells; ii) that paclitaxel seems to be more effective against mammary tumor cells in comparison to doxorubicin; and iii) targeting CXCR2 expression enhanced chemotherapeutic responses. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 693. doi:10.1158/1538-7445.AM2011-693