Transfected Tumor Cells Research Articles

Targeting and Regulating of an Oncogene via Nanovector Delivery of MicroRNA using Patient-Derived Xenografts.

In precision cancer nanomedicine, the key is to identify the oncogenes that are responsible for tumorigenesis, based on which these genetic drivers can be each specifically regulated by a nanovector-directed, oncogene-targeted microRNA (miRNA) for tumor suppression. Fibroblast Growth Factor Receptor 3 (FGFR3) is such an oncogene. The molecular tumor-subtype harboring FGFR3 genomic alteration has been identified via genomic sequencing and referred to as the FGFR3-driven tumors. This genomics-based tumor classification provides further rationale for the development of the FGFR3-targeted miRNA replacement therapy in treating patients with FGFR3 gene abnormity. However, successful miRNA therapy has been hampered by lacking of an efficient delivery vehicle. In this study, a nanovector is developed for microRNA-100 (miR-100) -mediated FGFR3 regulation. The nanovector is composed of the mesoporous magnetic clusters that are conjugated with ternary polymers for efficient miRNA in-vivo delivery. The miRNA-loading capacity of the nanovector is found to be high due to the polycation polymer functionalized mesoporous structure, showing excellent tumor cell transfection and pH-sensitive miRNA release. Delivery of miR-100 to cancer cells effectively down-regulates the expression of FGFR3, inhibits cell proliferation, and induces cell apoptosis in vitro. Patient-derived xenografts (PDXs) are used to evaluate the efficacy of miRNA delivery in the FGFR3-driven tumors. Notably, sharp contrasts are observed between the FGFR3-driven tumors and those without FGFR3 genomic alteration. Only the FGFR3-driven PDXs are significantly inhibited via miR-100 delivery while the non-FGFR3-driven PDXs are not affected, showing promise of precision cancer nanomedicine.

Identification of Novel Immune-Checkpoint Molecules on Multiple Myeloma Cells Using a High-Throughput Discovery Platform

Introduction:Multiple myeloma (MM) is a B-cell malignancy, characterized by accumulation of plasma cell clones in the bone marrow. While novel therapeutic agents like immunomodulatory drugs and proteasome inhibitors have improved overall survival of MM patients, the disease remains incurable in most patients. Several studies showed that immune-checkpoint molecules are expressed by myeloma cells and induce tumor-related immune suppression. Despite the promising results achieved by blocking CTLA4 and the PD-1/PD-L1 axis in the treatment of various solid tumors and Hodgkin's lymphoma, targeting these checkpoints did not induce objective responses in Phase I/II trials in MM patients. Therefore, identification of novel immune-checkpoints and defining the subsequent molecular mechanisms of inhibition are essential for further improvement.Methods:Our main goal is to identify novel MM-related immune-checkpoint molecules by taking advantage of a high-throughput (HT) RNAi screen and sequentially validate the role of candidate molecules, whose blockade could potentially induce anti-tumor immunity in MM patients.Methods:High-throughput RNAi screens offer a possibility to systemically search for immune-checkpoint molecules. Therefore, we established a high-throughput screening system to discern candidate molecules and evaluate their use as potential targets for multiple myeloma immunotherapy. We established a luciferase based read-out system by generating a stable luciferase expressing MM cell line (KMM-1-luc). To test the effect of immune-checkpoint molecules, KMM-1-luc cells were transfected with a siRNAs library targeting 2514 genes encoding for cell surface proteins, kinases and GPCRs. Transfected tumor cells were subsequently co-cultured with patient-derived HLA-matched Myeloma Infiltrating T Lymphocytes (MILs) and the effect of gene knock-down on T-cell mediated tumor lysis was measured.Results:Based on our primary HT-screening, we have identified 132 candidate molecules (hits) whose knockdown increased T-cell mediated killing more efficiently than the established checkpoint genes CCR9. To confirm the hits and the robustness of the screening, we re-tested the identified candidates in a secondary screening. Among these potential immune-checkpoints we selected 10 hits for further validation. So far, we were able to confirm expression of the hits at mRNA level and to validate siRNAs on-target effect by qPCR and luciferase-based cytotoxicity assay. Detailed results will be presented at the meeting.Conclusion:Altogether we optimized a high-throughput RNAi screen to discover novel immune-checkpoints that are potential immunotherapeutic targets for the treatment of multiple myeloma. We are currently investigating the mode of action of the candidate hits in vitro. Further in vivo validation of these immune-checkpoint molecules is still required for clinical studies. DisclosuresGoldschmidt:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Chugai: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Witzens-Harig:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Modification of tumor cell exosome content by transfection with wt-p53 and microRNA-125b expressing plasmid DNA and its effect on macrophage polarization.

Exosomes are responsible for intercellular communication between tumor cells and others in the tumor microenvironment. These microvesicles promote oncogensis and can support towards metastasis by promoting a pro-tumorogenic environment. Modifying the exosomal content and exosome delivery are emerging novel cancer therapies. However, the clinical translation is limited due to feasibility of isolating and delivery of treated exosomes as well as an associated immune response in patients. In this study, we provide proof-of-concept for a novel treatment approach for manipulating exosomal content by genetic transfection of tumor cells using dual-targeted hyaluronic acid-based nanoparticles. Following transfection with plasmid DNA encoding for wild-type p53 (wt-p53) and microRNA-125b (miR-125b), we evaluate the transgene expression in the SK-LU-1 cells and in the secreted exosomes. Furthermore, along with modulation of wt-p53 and miR-125b expression, we also show that the exosomes (i.e., wt-p53/exo, miR-125b/exo and combination/exo) have a reprogramed global miRNA profile. The miRNAs in the exosomes were mainly related to the activation of genes associated with apoptosis as well as p53 signaling. More importantly, these altered miRNA levels in the exosomes could mediate macrophage repolarization towards a more pro-inflammatory/antitumor M1 phenotype. However, further studies, especially in vivo studies, are warranted to assess the direct influence of such macrophage reprogramming on cancer cells and oncogenesis post-treatment. The current study provides a novel platform enabling the development of therapeutic strategies affecting not only the cancer cells but also the tumor microenvironment by utilizing the ‘bystander effect' through genetic transfer with secreted exosomes. Such modification could also support antitumor environment leading to decreased oncogenesis.

Abstract 2339: RNAi discovery platform to identify novel genes that prevent immune surveillance in pancreatic ductal adenocarcinoma (PDAC)

Abstract BACKGROUND: Being one of the most treatment-resistant cancer types, pancreatic ductal adenocarcinoma (PDAC) is characterized by its ability to escape immune surveillance by developing many immunological obstacles. These include a plethora of mechanisms that either dampen immune cell functionality, or foster tumor cell resistance towards immune attack. Immunotherapeutic strategies, such as immune checkpoint blockade, have proven clinical success in many cancer entities, but showed little clinical benefit in PDAC patients, emphasizing the need to identify more key players that could radically improve immunotherapy. AIM: We aim to systematically identify the whole arsenal of tumor-associated immune modulators by performing a high-throughput RNAi screen and subsequently validate novel therapeutic targets, whose blockade could potentially enhance anti-tumor immune response in PDAC patients. METHODS: We generated a luciferase-expressing PANC-1 cell line and knocked down 2514 genes using a siRNA library. Our library includes G-protein coupled receptors, protein kinases and 1117 surface proteins. We co-cultured HLA-A201+ matched tumor infiltrating lymphocytes (TILs) derived from a PDAC patient with the transfected tumor cells. We then measured the remaining luciferase intensity of the tumor cells as an estimation of TIL-mediated cytotoxicity. In order to exclude genes whose knock-down affected cell viability per se, we cultivated tumor cells with the siRNA library in the absence of TILs. RESULTS: We identified 155 candidate genes whose knock-down enhances TIL-mediated killing more efficiently than PD-L1 down-regulation. 35% of these genes are surface molecules and are most likely to directly mediate tumor immune evasion. Beside novel undescribed genes, our list contains well characterized immune modulators, supporting the reliability of our approach. Of note 13 of our hits were also found in a related melanoma screen and might play a role in the regulation of immune surveillance of different tumor entities. Among our candidates, 4 hits were chosen for further validation. We confirmed the expression of our selected candidates in several tumor cell lines and assessed the siRNA on-target effect using several non-overlapping siRNA sequences targeting the same hit. Transfection of PANC-1 with different siRNA sequences showed knock-down of the target gene as assessed via qPCR. Additionally we observed increased T-cell mediated killing as measured via luciferase-based killing assay and Chromium release assay. CONCLUSION: We set up a robust and systematic method to unravel novel key players of pancreatic cancer immune surveillance. Further functional validation of our candidate genes will prove their potential to be used as relevant therapeutic targets in the clinic. Citation Format: Antonio Sorrentino, Ayse Nur Menevse, Tillmann Michels, Nisit Khandelwal, Marco Breinig, Isabel Poschke, Valentina Volpin, Sabrina Wagner, Rienk Offringa, Michael Boutros, Philipp Beckhove. RNAi discovery platform to identify novel genes that prevent immune surveillance in pancreatic ductal adenocarcinoma (PDAC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2339.

Construction and characterization of gelonin and saporin plasmids for toxic gene-based cancer therapy.

Toxic gene therapy (or suicidal gene therapy) is gaining enormous interest, specifically for the treatment of cancer. The success of this therapy lies in several crucial factors, including the potency of gene products to kill the transfected tumor cells and the transfection ability of the transfection vehicles. To address the potency problem, in the present study, we engineered two separate mammalian transfection plasmids (pSAP and pGEL) containing genes encoding ribosome inactivating proteins (RIPs), gelonin and saporin. After the successful preparation and amplification of the plasmids, they were tested on various cancer cell lines (HeLa, U87, 9L, and MDA-MB-435) and a noncancerous cell line (293 HEK) using polyethyleneimine (PEI) as the transfection agent. Transfection studies performed under varying gene concentration, incubation time, and gene-to-PEI ratios revealed that, compared to the treatment of pGFP (GFP expression plasmid)/PEI, both pGEL/PEI and pSAP/PEI complexes could induce significantly augmented cytotoxic effects at only 2μg/mL gene concentration. Importantly, these cytotoxic effects were observed universally in all tested cancer cell lines. Overall, this study demonstrated the potential of pGEL and pSAP as effective gene candidates for the toxic gene-based cancer therapy.

Transcription factor Oct-1 stimulates the release of Mts1/S100A4 protein by the cancer cells.

The effect of the transcription factor Oct-1 (POU2F1) on the expression of the tumor cell marker metastasin (Mts1/S100A4) was studied. Comparative analysis of various tumor lines showed no clear correlation between the expression level of Mts1/S100A4 and the content of Oct-1. However, at stable transfection of tumor cells with Oct-1A, Oct-1L, and Oct-1X isoforms we detected an elevated level of Oct-1, which stimulated Mts1/S100A4 secretion. These findings extend our understanding of the molecular mechanisms of the tumorigenic effect of Oct-1.

Bacterial Toxins for Oncoleaking Suicidal Cancer Gene Therapy.

For suicide gene therapy, initially prodrug-converting enzymes (gene-directed enzyme-producing therapy, GDEPT) were employed to intracellularly metabolize non-toxic prodrugs into toxic compounds, leading to the effective suicidal killing of the transfected tumor cells. In this regard, the suicide gene therapy has demonstrated its potential for efficient tumor eradication. Numerous suicide genes of viral or bacterial origin were isolated, characterized, and extensively tested in vitro and in vivo, demonstrating their therapeutic potential even in clinical trials to treat cancers of different entities. Apart from this, growing efforts are made to generate more targeted and more effective suicide gene systems for cancer gene therapy. In this regard, bacterial toxins are an alternative to the classical GDEPT strategy, which add to the broad spectrum of different suicide approaches. In this context, lytic bacterial toxins, such as streptolysin O (SLO) or the claudin-targeted Clostridium perfringens enterotoxin (CPE) represent attractive new types of suicide oncoleaking genes. They permit as pore-forming proteins rapid and also selective toxicity toward a broad range of cancers. In this chapter, we describe the generation and use of SLO as well as of CPE-based gene therapies for the effective tumor cell eradication as promising, novel suicide gene approach particularly for treatment of therapy refractory tumors.

Abstract 245: Identification of novel immune checkpoints as potential therapeutic targets in pancreatic ductal adenocarcinoma (PDAC) using RNAi screening

Abstract BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) accounts for 95% of pancreatic cancers and constitutes the fourth leading cause of cancer related death worldwide. In contrast to other malignancies, PDAC is highly resistant to chemotherapy and radiotherapy. Additionally, few immunotherapies are currently available because this malignancy was thought to be poorly immunogenic. Recent studies have shown that infiltration of immune cells in biopsies of PDAC patients correlates with improved clinical outcome. Nevertheless, tumor cells can elude the immune system through several inhibitory mechanisms including the expression of immune checkpoints. These are a plethora of molecules that can either boost or dampen the T-cell receptor (TCR) signaling. Some of these molecules, such as PD-L1, have been successfully used as therapeutic targets of novel anticancer drugs. AIM: We hypothesize that many immune checkpoint molecules on tumor cells remain undiscovered and we performed a high-throughput RNAi screen to unravel the whole arsenal of immune modulators. METHODS: We generated a luciferase-expressing PANC-1 cell line and knocked down 2514 genes using a siRNA library. Our library included G-protein coupled receptors, protein kinases and 1117 surface proteins. We co-cultured HLA-A201+ matched tumor infiltrating lymphocytes (TILs) derived from a PDAC patient with the transfected tumor cells. We then measured the remaining luciferase intensity of the tumor cells as an estimation of TIL-mediated cytotoxicity. In order to exclude genes whose knock-down affected cell viability per se, we cultivated tumor cells with the siRNA library in the absence of TILs. Data were analyzed with the cellHTS2 R package. RESULTS: Our screen revealed 155 candidate genes whose knock-down enhances TIL-mediated killing more efficiently than PD-L1 down-regulation. 35% of these genes are surface molecules and are most likely to directly mediate tumor immune evasion. Beside novel undescribed immune checkpoints, our list contains well characterized immune modulators, supporting the reliability of our approach. Of note 13 of our hits were also found in a related melanoma screen and might play a role in the regulation of immune surveillance of many solid tumors. Among our candidates, TONI1 was one of the most prominent hits. So far, we confirmed the role of TONI1 in inhibiting TIL-mediated killing both in chromium release and luciferase based kill assays. Additionally we detected increased T-cell activity upon TONI1 down-regulation, as measured with interferon-γ ELISPOT and TNF-α ELISA. Since the presented work is considered for patent protection, some gene targets are masked. CONCLUSION: We set up a robust and systematic method to identify novel immune checkpoints for pancreatic cancer. Further functional validation of our candidate genes will prove their use as therapeutic targets. Citation Format: Antonio Sorrentino, Tillmann Michels, Ayse Nur Menevse, Nisit Khandelwal, Marco Breinig, Isabel Poschke, Rienk Offringa, Michael Boutros, Philipp Beckhove. Identification of novel immune checkpoints as potential therapeutic targets in pancreatic ductal adenocarcinoma (PDAC) using RNAi screening. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 245. doi:10.1158/1538-7445.AM2015-245

Novel Antitumor Strategy Utilizing a Plasmid Expressing a Mycobacterium tuberculosis Antigen as a "Danger Signal" to Block Immune Escape of Tumor Cells.

Immune escape of tumor cells is one of the main obstacles hindering the effectiveness of cancer immunotherapy. We developed a novel strategy to block immune escape by transfecting tumor cells in vivo with genes of pathogenic antigens from Mycobacterium tuberculosis (TB). This induces presentation of the TB antigen on tumor cell surfaces, which can be recognized by antigen presenting cells (APCs) as a “danger signal” to stimulate antitumor immune response. This strategy is also expected to amplify the immune response against tumor-associated antigens, and block immune escape of the tumor. DNA/PEI/chondroitin sulfate ternary complex is a highly effective non-viral gene vector system for in vivo transfection. A therapeutic complex was prepared using a plasmid encoding the TB antigen, early secretory antigenic target-6 (ESAT-6). This was injected intratumorally into syngeneic tumor-bearing mice, and induced significant tumor growth suppression comparable to or higher than similar complexes expressing cytokines such as interleukin-2 (IL-2) and interleukin-12 (IL-12). Co-transfection of the cytokine-genes and the ESAT-6-gene enhanced the antitumor efficacy of either treatment alone. In addition, complete tumor regression was achieved with the combination of ESAT-6 and IL-2 genes.

Abstract 3532: Hypoxia is a master regulator of Drosha- and Dicer-dependent miRNA biogenesis in cancer

Abstract Background: Drosha and Dicer are 2 key enzymes involved in miRNA biogenesis. Individual regulators of Dicer (e.g let7) have been implicated, but the underlying mechanisms are currently poorly understood. Here, we identified new mechanisms of deregulation of miRNA biogenesis in tumor cells, whereby hypoxia causes reduction in Drosha and Dicer. Methods and Results: Differential levels of Drosha and Dicer was found between tumor samples and their expression correlated negatively with CA9, a hypoxia marker (Drosha vs. CA9 r=-0.65, Dicer vs. CA9 r=-0.69; p<0.05). We further found that Drosha and Dicer are down-regulated by >70% in hypoxic compared to normoxic conditions across a panel of ovarian and breast cancer cell lines and microdisected tumor tissues. Analysis of TCGA data showed that the expressions of Drosha and Dicer or hypoxia are independent predictors of poor patient survival. Furthermore, RNA-sequencing and mature miRNA array analyses both revealed a significant disruption in miRNA maturation when cells were exposed to hypoxia. Through ChIP assays and promoter reporter studies, we found that ETS1 and ELK1 are responsible for transcriptionally repressing Drosha expression under hypoxia by binding to its promoter region. We further show that ETS1/ELK1 recruit ARID5B and HDAC1 to methylate Drosha promoter. In contrast to Drosha, Dicer level is altered post-transcriptionally under hypoxia. Several miRNAs that are up-regulated under hypoxia are predicted to target Dicer. By transfecting tumor cells with miRNA mimics or anti-miR constructs along with 3′ UTR luciferase assays, we showed that miR-630 is a strong regulator of Dicer in hypoxic conditions. Bioinformatics analysis of downregulated miRNAs and their gene targets from RNA-seq data identified novel miRNA (let7a, miR-30c, miR-135a, miR-146a)-mRNA (RHOB, TAGLN, JUN, CTGF, SERTAD, TXNIP, JAG1) interactions aiding metastasis under hypoxia. Given the potential for anti-VEGF therapies in inducing significant hypoxia in tumors, we examined the biological effects of anti-miR-630 or siETS1/ELK1 in orthotopic ovarian and breast cancer mouse models. We first demonstrated that in vivo tumor samples treated with anti-VEGF therapy results in significant Drosha and Dicer down-regulation. ETS1+ELK1siRNA or anti-miR630 DOPC nanoparticles in vivo rescued Drosha and Dicer expression under anti-VEGF therapy, resulting in a significant reduction in cancer metastasis (p<0.05). Conclusion: In summary, these findings provide new insights into the mechanisms underlying Drosha and Dicer downregulation following hypoxia and resultant effects on cancer metastasis. Citation Format: Rajesha Rupaimoole, Cristina Ivan, Chad Pecot, Sherry Wu, Sunila Pradeep, Behrouz Zand, Archana Nagaraja, Kshipra Gharpure, Heather Dalton, Nouara Sadaoui, Wei Zhang, Gabriel Lopez-Berestein, Anil Sood. Hypoxia is a master regulator of Drosha- and Dicer-dependent miRNA biogenesis in cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3532. doi:10.1158/1538-7445.AM2014-3532

Abstract 5026: B7-H1 confers tumor chemoresistance by regulating MAPK/ERK activation

Abstract Development of resistance to chemotherapy and immunotherapy is a major obstacle in extending the survival of cancer patients. Although several molecular mechanisms have been identified that can contribute to chemoresistance, the role of immune checkpoint molecules in tumor chemoresistance has received little consideration. Elevated expression of B7-H1 (also named PD-L1) is predictive of an aggressive disease course, including increases in disease progression and cancer-related mortality in a variety of cancers (ovary, breast, liver, pancreas, esophagus, colon and lung). Although the aggressiveness of B7-H1 positive tumors has been attributed to B7-H1's immune-suppressive function, B7-H1 itself may be directly altering tumor cell intracellular signaling pathways promoting acquisition of drug resistance. It has been reported that overexpression of B7-H1 confers chemoresistance in human cancers. However, the mechanisms by which B7-H1 contributes to tumor chemoresistance have yet to be defined. We show that B7-H1 transfected tumor cells are resistant to chemotherapy. This resistance is due to increased activation of MAPK/ERK pathway in tumor cells with B7-H1 overexpression. Inhibition of ERK activation restored drug sensitivity of B7-H1 positive tumor cells. We further analyzed the downstream elements of B7-H1 signaling pathway and identified a new B7-H1 associated protein that is involved in DNA damage repair and MAPK/ERK activation mechanisms. We conclude that B7-H1 mediates tumor chemoresistance by enhancing the activation of MAPK/ERK pathway via its intracellular signaling pathway. Our studies may identify a novel pharmaceutical target for treatment of B7-H1 positive refractory tumor cells. Citation Format: Amanda Orzechowski, Haidong Dong. B7-H1 confers tumor chemoresistance by regulating MAPK/ERK activation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5026. doi:10.1158/1538-7445.AM2014-5026

Altered expression of apoptotic genes in response to OCT4B1 suppression in human tumor cell lines.

OCT4B1 is a newly discovered spliced variant of OCT4 which is primarily expressed in pluripotent and tumor cells. Based on our previous studies, OCT4B1 is significantly overexpressed in tumors, where it endows an anti-apoptotic property to tumor cells. However, the mechanism by which OCT4B1 regulates the apoptotic pathway is not yet elucidated. Here, we investigated the effects of OCT4B1 suppression on the expression alteration of 84 genes involved in apoptotic pathway. The AGS (gastric adenocarcinoma), 5637 (bladder tumor), and U-87MG (brain tumor) cell lines were transfected with OCT4B1 or irrelevant siRNAs. The expression level of apoptotic genes was then quantified using a human apoptosis panel-PCR kit. Our data revealed an almost similar pattern of alteration in the expression profile of apoptotic genes in all three studied cell lines, following OCT4B1 suppression. In general, the expression of more than 54 apoptotic genes (64 % of arrayed genes) showed significant changes. Among these, some up-regulated (CIDEA, CIDEB, TNFRSF1A, TNFRSF21, TNFRSF11B, TNFRSF10B, and CASP7) and down-regulated (BCL2, BCL2L11, TP73, TP53, BAD, TRAF3, TRAF2, BRAF, BNIP3L, BFAR, and BAX) genes had on average more than tenfold gene expression alteration in all three examined cell lines. With some minor exceptions, suppression of OCT4B1 caused upregulation of pro-apoptotic and down-regulation of anti-apoptotic genes in transfected tumor cells. Uncovering OCT4B1 down-stream targets could further elucidate its part in tumorigenesis, and could lead to finding a new approach to combat cancer, based on targeting OCT4B1.

Phyllodes tumor of the breast: role of Axl and ST6GalNAcII in the development of mammary phyllodes tumors.

Phyllodes tumor exhibits an aggressive growth. The expression of many biological markers has been explored to discriminate between different grades of phyllodes tumor and to predict their behavior. The purpose of this study was to evaluate the implications of Axl and ST6GalNAcII in phyllodes tumors. Real-time PCR, Western blot, and immunohistochemical were used to analyze differential expression of ST6GalNAcII and Axl in phyllodes tumor (PT) cell lines and tissue specimens. RNAi assay, ECM invasion assay, and tumorigenicity assay were used to analyze the altered expression of ST6GalNAcII gene effects on the expression of Axl and invasive ability of phyllodes tumor cells in vitro and in vivo. Compared to benign tumors, borderline and malignant ones showed a remarkable increase in mRNA levels of Axl and ST6GalNAcII gene, and it was higher in malignant tumor cells than in borderline tumor cells. When ST6GalNAcII was silenced, compared to the control, the expression level of Axl was significantly reduced in malignant tumor cell transfectants and knockdown of ST6GalNAcII gene significantly inhibited invasive activity in malignant tumor cells. The high expression of ST6GalNAcII and Axl was significantly correlated with tumor grade and distance metastasis by immunohistochemical analysis. Axl and ST6GalNAcII expression increases with increasing tumor grade in mammary phyllodes tumors. ST6GalNAc II might be participated in the glycosylation of Axl, and this Axl glycosylation may mediate the tumorigenicity, invasion, and distant metastasis of PT cells.

Expression Pattern of Carbonic Anhydrase IX in Medullary Thyroid Carcinoma Supports a Role for RET-Mediated Activation of the HIF Pathway

Medullary thyroid carcinoma is a relatively rare tumor with poor prognosis and therapy response. Its phenotype is determined by both genetic alterations (activating RET oncoprotein) and physiological stresses, namely hypoxia [activating hypoxia-inducible factor (HIF)]. Here, we investigated the cooperation between these two mechanisms. The idea emerged from the immunohistochemical analysis of carbonic anhydrases (CA) IX and XII expression in thyroid cancer. Although CAXII was present in all types of thyroid carcinomas, CAIX, a direct HIF target implicated in tumor progression, was associated with aggressive medullary and anaplastic carcinomas, and its expression pattern in medullary thyroid carcinomas suggested contribution of both hypoxic and oncogenic signaling. Therefore, we analyzed the CA9 promoter activity in transfected tumor cells expressing RET and/or the HIF-α subunit. We showed that overexpression of both wild-type and mutant RET can increase the CA9 promoter activity induced by HIF-1 (but not HIF-2) in hypoxia. Similar results were obtained with another HIF-1-regulated promoter derived from the lactate dehydrogenase A gene. Moreover, inhibition of the major kinase pathways, which transmit signals from RET and regulate HIF-1, abrogated their cooperative effect on the CA9 promoter. Thus, we brought the first experimental evidence for the crosstalk between RET and HIF-1 that can explain the increased expression of CAIX in medullary thyroid carcinoma and provide a rationale for therapy simultaneously targeting both pathways.

PEGylated poly(amine-co-ester) micelles as biodegradable non-viral gene vectors with enhanced stability, reduced toxicity and higher in vivo transfection efficacy.

Nanosized micelles based on cationic, amphiphilic poly(ethylene glycol)-poly(ω-pentadecalactone-co-N-methyldiethyleneamine-co-sebacate) (PEG-PPMS) block copolymers have been successfully developed to serve as a new type of biodegradable non-viral vectors for DNA delivery. PEG-PPMS copolymers with various compositions were synthesized in one step via lipase-catalyzed copolymerization of ω-pentadecalactone (PDL), N-methyldiethanolamine (MDEA) and diethyl sebacate (DES) with poly(ethylene glycol) methyl ether (MeO-PEG-OH). The effects of PEG molecular weight, PEG and PDL contents on the biological properties (including the gene transfection efficiency) of the copolymer micelles were investigated. The LucDNA-loaded micelles formed from the copolymers with 30-50 wt% PEG showed high stability in serum-containing aqueous medium, which is in sharp contrast to rapid aggregation of LucDNA/PPMS polyplex particles. The conjugation of PEG to PPMS chains significantly reduces the cytotoxicity and hemolysis activity of the PEG-PPMS micelles. Compared to PEG-free PPMS, the micelles of PEG-PPMS copolymers with optimal compositions (e.g., 42%PEG5K-PPMS-10%PDL and 42%PEG5K-PPMS-20%PDL) exhibited enhanced capability to condense and protect DNA. Although the optimized micelles showed comparable or slightly lower gene transfection efficacy than the reference PPMS in vitro, the efficiency of LucDNA/42%PEG5K-PPMS-20%PDL micelles in transfecting tumor cells in mice was twice as high as that of LucDNA/PPMS polyplex particles due to their strong DNA condensation ability and excellent stability under physiological conditions. The PEG-PPMS micelle system with improved properties is a family of potentially promising non-viral vectors for in vivo delivery of therapeutic genes to treat tumors.

Investigating a pathogenic role for TXNDC5 in tumors

The expression of TXNDC5, which is induced by hypoxia, stimulates cell proliferation and angiogenesis. The increased cell proliferation, angiogenesis and hypoxia are main features of tumor tissues. The present study aimed to characterize the expression of TXNDC5 in various tumor types and to investigate the role of TXNDC5 in the growth, proliferation and migration of tumor cells. The study also determined susceptibility of TXNDC5 gene on tumor risk. The expression of TXNDC5 in tumor tissues was determined by immunohistochemistry using a tissue array that contained various types of tumor tissues. The expression levels of TXNDC5 in tumor tissues and healthy tissues were quantitatively analyzed using western blotting. Furthermore, HeLa cells and U2OS cells were treated with anti-TXNDC5 siRNA to knockdown the expression levels of TXNDC5 to study its role in cell proliferation and migration. The cell proliferation and migration of the transfected tumor cells were determined by MTT and Transwell migration assays, respectively. Ninety-six tag SNPs across the TXNDC5 locus were genotyped using custom‑designed Illumina 384-SNP VeraCode microarrays. Our immunohistochemical staining revealed significant expression of TXNDC5 in breast invasive ductal carcinomas, cervical squamous cell carcinomas, esophageal squamous cell carcinomas, gastric carcinomas, hepatocellular carcinomas, ovarian papillary serous carcinomas, prostate cancers and undifferentiated cell carcinomas of the lung. Western blot analysis also detected significantly higher TXNDC5 expression in tumor tissues of breast cancers, gastric adenocarcinomas and rectal cancers compared to the adjacent healthy tissues. Decreased growth and invasive potential were observed in cultured HeLa cells and U2OS cells when TXNDC5 gene expression was knocked down. The case-control analysis showed a significant difference in allele frequency and genotype frequency for rs9505298, rs7771314, rs2815128, rs13210097 and rs9392182 between cervical carcinoma, esophageal carcinoma and liver cancer patients and controls. These results suggest that TXNDC5 has increased expression in many tumors that is involved in the proliferation and migration of tumor cells, acting as a tumor-enhancing gene. The study also suggests that TXNDC5 gene is susceptible to cervical carcinoma, esophageal carcinoma and liver cancer risk.

Intracellular Poly(I:C) Initiated Gastric Adenocarcinoma Cell Apoptosis and Subsequently Ameliorated NK Cell Functions

Natural killer (NK) cells are granular lymphocytic cells that exert essential functions in viral infection defense and tumor immune surveillance. However, the functions of NK cells were impaired in cancer patients. Polycytidylic acid [poly(I:C)] has been used as an immune adjuvant to improve innate and adaptive immune responses. In this study, intracellular poly(I:C) could trigger gastric adenocarcinoma cells apoptosis quickly. Meanwhile, the sensitivity of poly(I:C)-treated gastric adenocarcinoma cells to NK cell cytolysis was increased, concomitant with the elevated expression of MICA/B and Fas. Furthermore, the cytolytic activity of NK cells against tumor cells was augmented significantly by the supernatant from poly(I:C)-transfected tumor cells compared with NK cells treated by the supernatant from untreated tumor cells, as well as the proliferation and migration abilities of NK cells. In this process, the activating receptors and cytolysis-associated molecules of NK cells were up-regulated. Further investigation showed that type I interferon (IFN) produced by poly(I:C)-transfected gastric adenocarcinoma cells played an important role in this process. Our findings demonstrated that intracellular poly(I:C) not only triggered gastric adenocarcinoma cell apoptosis, but also enhanced NK responses via inducing type I IFN production by gastric adenocarcinoma cells. These functions make poly(I:C) a promising therapeutic medicine for gastric adenocarcinoma.

Tumstatin transfected into human glioma cell line U251 represses tumor growth by inhibiting angiogenesis

Background Angiogenesis is a prerequisite for tumor growth and plays an important role in rapidly growing tumors, such as malignant gliomas. A variety of factors controlling the angiogenic balance have been described, and among these, the endogenous inhibitor of angiogenesis, tumstatin, has drawn considerable attention. The current study investigated whether expression of tumstatin by glioma cells could alter this balance and prevent tumor formation. Methods We engineered stable transfectants from human glioma cell line U251 to constitutively secrete a human tumstatin protein with c-myc and polyhistidine tags. Production and secretion of the tumstatin-c-myc-His fusion protein by tumstatin-transfected cells were confirmed by Western blotting analysis. In the present study, we identify the anti-angiogenic capacity of tumstatin using several in vitro and in vivo assays. Student's t-test and one-way analysis of variance (ANOVA) test were used to determine the statistical significance in this study. Results The tumstatin transfectants and control transfectants (stably transfected with a control plasmid) had similar in vitro growth rates compared to their parental cell lines. However, the conditioned medium from the tumstatin transfected tumor cells significantly inhibits proliferation and causes apoptosis of endothelial cells. It also inhibits tube formation of endothelial cells on Matrigel. Examination of armpit tumors arising from cells overexpressing tumstatin repress the growth of tumor, accompanying the decreased density of CD31 positive vessels in tumors ((5.62±1.32)/HP), compared to the control-transfectants group ((23.84+1.71)/HP) and wild type U251 glioma cells group ((29.33+4.45)/HP). Conclusion Anti-angiogenic gene therapy using human tumstatin gene may be an effective strategy for the treatment of glioma.

Interleukin-15 in Gene Therapy of Cancer

Interleukin-15 (IL-15) exerts powerful stimulatory effects on lymphocyte subsets that result in antiviral and antitumoral activities. The functions of this cytokine are mainly mediated in a cell-to-cell contact fashion termed IL-15 trans-presentation. This function is mediated by a cell which tethers IL-15 to its plasmatic membrane complexed to IL-15 receptor alpha (IL-15Rα). Such surface complexes interact with interleukin-2 receptor beta and gamma on the adjacent cell to elicit signaling. Unlike interleukin-2, IL-15 protects from activation-induced cell death and does not promote regulatory cells. These features underlie its activity against transplanted tumors and its adjuvanticity in tumor and viral vaccines. The GMP-manufactured recombinant protein is undergoing clinical trials but its rapid renal clearance calls for biotechnological strategies to increase molecular weight and ensure IL-15Rα. trans-presentation. Since early efforts with stable transfected tumor cells, IL-15 has been tested in a variety gene therapy approaches. Those mainly include transfer of expression cassettes to tumor cells, T cells, dendritic cells, vaccination sites and the liver as a biofactory organ. Detailed mechanistic knowledge of IL-15 biology is envisaged to make the most of a powerful immunotherapeutic tool ranked as one of the most promising for cancer immunotherapy.

19F-MRS/1H-MRI dual-function probe for detection of β-galactosidase activity

Because of the importance of lacZ gene in various applications ranging from molecular biology to clinical trials, the development of non-invasive bimodal techniques for improving precision and accuracy to assay gene expression has attracted much attention. In this paper, we propose a dual-function probe for synergistic combination of 19F-MRS/1H-MRI to simultaneously detect β-gal activity. Based on this strategy, we have designed, synthesized and characterized a series of 19F-MRS/1H-MRI reporters, and demonstrated the feasibility of 1-O-(β-D-galactopyranosyl)-3-fluorocatechol MGD-3-FCAT for assessing β-gal activity in solution and in vitro with lacZ transfected tumor cells as well, by the characterization of β-gal responsive 19F-chemical shift changes ΔδF, hydrolytic kinetics, and T1, T2 relaxation mapping.