Resistant Human Carcinoma Cells Research Articles

Intracellular targeting of the oncogenic MUC1-C protein with a GO-203 nanoparticle formulation overcomes MCL-1- and BFL-1-mediated resistance in human carcinoma cells.

e14053 Background: Aberrant expression of MCL-1 and BFL-1, the pro-survival members of the Bcl-2 family, is a major cause of drug resistance in human cancers. Mucin 1 (MUC1) is a heterodimeric oncoprotein that is aberrantly expressed in most human carcinomas. Notably, there is no known relationship between the oncogenic MUC1 C-terminal subunit (MUC1-C) and these anti-apoptotic proteins. Methods: MUC1-C was targeted in breast, lung and colon cancer cells by a stable shRNA, a tetracycline-inducible shRNA, or a pharmacologic peptide inhibitor GO-203. MCL-1 was inhibited by siRNA or the MS-1 peptide. In vitro and in vivo studies were conducted using our polymeric nanoparticles (NPs) for intracellular delivery of peptide cargos. Cells were selected for resistance to ABT-737 or ABT-263, which target BCL-2, BCL-XL and BCL-w, but not MCL-1 and BFL-1. Results: Targeting MCL-1 with MS-1/NPs inhibited the survival of parental cancer cells in vitro and in vivo, and was associated with upregulation of BFL-1 levels. In addition, MS-1/NPs treatment had limited effects on ABT-resistant cells because of increased BFL-1 expression. Importantly, we found that targeting MUC1-C is associated with suppression of both MCL-1 and BFL-1. Mechanistically, MUC1-C (i) stabilizes MCL-1 by activating the MEK→ERK and PI3K→AKT pathways, and (ii) induces BFL-1 through the NF-κB p65 pathway. Treatment with GO-203/NPs suppressed proliferation of parental and ABT-resistant cells. In addition, we show that combining GO-203 with ABT-737 is synergistic in inhibiting survival of parental and ABT-resistant cells. Conclusions: These findings demonstrate that targeting MUC1-C with GO-203/NPs is a potential strategy for abrogating MCL-1- and BFL-1-mediated resistance.

High levels of expression of the transcription factor Brachyury induce resistance of human carcinoma cells to immune-mediated attack

Meeting abstracts The phenomenon of epithelial-mesenchymal transition (EMT) is a phenotypic switch that allows epithelial tumor cells to acquire features of mesenchymal cells, including the ability to migrate and invade and, therefore, to disseminate from the primary site. In addition to promoting

β-Elemene enhances susceptibility to cisplatin in resistant ovarian carcinoma cells via downregulation of ERCC-1 and XIAP and inactivation of JNK

β-Elemene is a promising new plant-derived drug with broad-spectrum anticancer activity. It also increases cisplatin cytotoxicity and enhances cisplatin sensitivity in resistant human carcinoma cells. However, little is known about the mechanism of its action. To explore the potential therapeutic application of β-elemene as a drug-resistance modulator, this study investigated the underlying mechanism of β-elemene activity in cisplatin-resistant ovarian cancer cells. β-Elemene enhanced cisplatin sensitivity to a much greater extent in chemoresistant A2780/CP70 and MCAS human ovarian carcinoma cells compared to the chemosensitive parental cell line A2780. The dose-modifying factors for cisplatin were between 35 and 60 for A2780/CP70 cells and between 1.6 and 2.5 for A2780 cells. In the cisplatin-resistant ovarian carcinoma cells, β-elemene abrogated cisplatin-induced expression of excision repair cross-complementation group-1 (ERCC-1), a marker gene in the nucleotide excision repair pathway that repairs cisplatin-caused DNA damage. In addition, β-elemene not only reduced the level of X-linked inhibitor of apoptosis protein (XIAP), but also downregulated cisplatin-mediated XIAP expression in chemoresistant cells. Furthermore, β-elemene blocked the cisplatin-stimulated increase in the level of phosphorylated c-Jun NH2-terminal kinase (JNK) in these cells. These novel findings suggest that the β-elemene enhancement of cisplatin sensitivity in human chemoresistant ovarian cancer cells is mediated at least in part through the impairment of DNA repair activity and the activation of apoptotic signaling pathways, thereby making resistant ovarian cancer cells susceptible to cisplatin-induced cell death.

Abstract 278: High levels of expression of the transcription factor Brachyury induce resistance of human carcinoma cells to immune-mediated attack.

Abstract The phenomenon of epithelial-mesenchymal transition (EMT) is recognized as a relevant process during the progression of carcinomas. EMT is a phenotypic switch that allows epithelial tumor cells to acquire features of mesenchymal cells, including the ability to migrate and invade and, therefore, to disseminate from the primary site. In addition to promoting tumor dissemination, various reports have demonstrated that acquisition of features of EMT associates with tumor resistance to the cytotoxic effects of chemotherapy, radiation, and some targeted therapies. Presently, no studies have been conducted to thoroughly investigate whether this phenotypic switch may also contribute to the escape of tumors from host immune-surveillance and immune-mediated rejection. Our laboratory has characterized the T-box transcription factor Brachyury as a tumor-associated antigen and a regulator of EMT in human carcinomas. Currently, a Brachyury-based, recombinant yeast cancer vaccine is ongoing Phase I clinical testing for the treatment of patients with advanced carcinomas. Work in our laboratory has demonstrated that high levels of Brachyury expression in human carcinoma cell lines is associated with increased resistance to both chemo- and radiation therapies. In the present study, human epithelial carcinoma cell lines undergoing EMT via Brachyury over-expression and their epithelial tumor cell counterparts were comparatively utilized to evaluate whether EMT imparts resistance to immune-mediated attack. Our results demonstrate a bell-shaped relationship between the levels of Brachyury expression and the susceptibility of human carcinoma cell lines to lysis by immune cells. While tumor cells with low/intermediate levels of Brachyury expression are vulnerable to cell lysis, those with high levels of Brachyury expression are very resistant to lysis by immune cells. Our results demonstrate that a high level of Brachyury expression in human tumor cells reduces their susceptibility to antigen-specific CD8+ cytotoxic T cells and innate, natural killer (NK) and lymphokine-activated killer (LAK) cells. While the mechanisms involved in this phenomenon are currently under investigation in our laboratory, preliminary studies suggest that antigen processing and/or presentation is not responsible for the defective immune-mediated cytotoxicity of EMT-tumors. Altogether our results indicate that targeting the process of EMT may be a successful strategy not only to interfere with tumor dissemination but also to increase the effectiveness of immunotherapeutic interventions against metastatic tumors. Citation Format: Duane H. Hamilton, Bruce Huang, Romaine I. Fernando, Kwong-Yok Tsang, Claudia M. Palena. High levels of expression of the transcription factor Brachyury induce resistance of human carcinoma cells to immune-mediated attack. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 278. doi:10.1158/1538-7445.AM2013-278

Complement resistance of human carcinoma cells depends on membrane regulatory proteins, protein kinases and sialic acid.

Nucleated cells employ several strategies to evade killing by homologous complement. We studied complement resistance in the human carcinoma cell lines (CA) T47D (mammary), SKOV3 (ovarian), and PC-3 (prostate) with emphasis on the following mechanisms of defense: 1. Expression and shedding of the membrane complement regulatory proteins (mCRP) CD46, CD55 and CD59; 2. Resistance based on protein phosphorylation; 3. Cell surface expression of sialic acid residues; 4. Desensitization to complement upon exposure to sublytic complement doses. Anti-mCRP antibody blocking experiments demonstrated that CD59 is the main mCRP protecting these CA from complement. Soluble CD59 was also found in supernates of PC-3> SKOV3 > T47D cells. Second, inhibitors of PKC, PKA and MEK sensitized the CA to lysis, thus implicating these protein kinases in CA complement resistance. Third, removal of sialic acid residues with neuraminidase also sensitized CA to lysis. Finally, exposure of CA to sublytic doses of complement conferred on them enhanced resistance to lytic complement doses in a PKC-dependent process. Combined treatment of CA with anti-CD59 antibodies, PD98059 (a MEK inhibitor) and neuraminidase produced a large enhancement in CA sensitivity to complement. Our results show that CD59 and sialic acid residues present on the cell surface, and intracellular processes involving protein phosphorylation act additively to secure CA resistance to complement-mediated lysis. Therefore, the effectiveness of antibody- and complement-based cancer immunotherapy will markedly improve by suppression of the various complement resistance mechanisms.

Structure of a novel multidrug resistance modulator, irciniasulfonic acid, isolated from a marine sponge, Ircinia sp.

Irciniasulfonic acid was obtained from a marine sponge of Ircinia sp. Spectroscopic and chemical analyses revealed its structure consists of three different kinds of acids, i.e. common fatty acids, a novel unsaturated branched C-10 fatty acid and an isethionic acid. Irciniasulfonic acid and deacyl irciniasulfonic acid reverse multidrug resistance in human carcinoma cells caused by overexpression of membrane glycoprotein.

Agosterol A, a novel polyhydroxylated sterol acetate reversing multidrug resistance from a marine sponge of Spongia sp.

Agosterol A ( 1) has been isolated from a marine sponge of Spongia sp. and the absolute stereo-structure elucidated. Agosterol A ( 1) is a novel polyhydroxylated sterol acetate, which completely reverses multidrug resistance in human carcinoma cells caused by overexpression of two kinds of membrane glycoprotein.