Cyclin D1 extensively reprograms metabolism to support biosynthetic pathways in hepatocytes

Cell proliferation requires metabolic reprogramming to accommodate biosynthesis of new cell components, and similar alterations occur in cancer cells. However, the mechanisms linking the cell cycle machinery to metabolism are not well defined. Cyclin D1, along with its main partner cyclin-dependent kinase 4 (Cdk4), is a pivotal cell cycle regulator and driver oncogene that is overexpressed in many cancers. Here, we examine hepatocyte proliferation to define novel effects of cyclin D1 on biosynthetic metabolism. Metabolomic studies reveal that cyclin D1 broadly promotes biosynthetic pathways including glycolysis, the pentose phosphate pathway, and the purine and pyrimidine nucleotide synthesis in hepatocytes. Proteomic analyses demonstrate that overexpressed cyclin D1 binds to numerous metabolic enzymes including those involved in glycolysis and pyrimidine synthesis. In the glycolysis pathway, cyclin D1 activates aldolase and GAPDH, and these proteins are phosphorylated by cyclin D1/Cdk4 in vitro. De novo pyrimidine synthesis is particularly dependent on cyclin D1. Cyclin D1/Cdk4 phosphorylates the initial enzyme of this pathway, carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase (CAD), and metabolomic analysis indicates that cyclin D1 depletion markedly reduces the activity of this enzyme. Pharmacologic inhibition of Cdk4 along with the downstream pyrimidine synthesis enzyme dihydroorotate dehydrogenase synergistically inhibits proliferation and survival of hepatocellular carcinoma cells. These studies demonstrate that cyclin D1 promotes a broad network of biosynthetic pathways in hepatocytes, and this model may provide insights into potential metabolic vulnerabilities in cancer cells.

Protein kinase CK2 – diverse roles in cancer cell biology and therapeutic promise

The association of protein kinase CK2 (formerly casein kinase II or 2) with cell growth and proliferation in cells was apparent at early stages of its investigation. A cancer-specific role for CK2 remained unclear until it was determined that CK2 was also a potent suppressor of cell death (apoptosis); the latter characteristic differentiated its function in normal versus malignant cells because dysregulation of both cell growth and cell death is a universal feature of cancer cells. Over time, it became evident that CK2 exerts its influence on a diverse range of cell functions in normal as well as in transformed cells. As such, CK2 and its substrates are localized in various compartments of the cell. The dysregulation of CK2 is documented in a wide range of malignancies; notably, by increased CK2 protein and activity levels with relatively moderate change in its RNA abundance. High levels of CK2 are associated with poor prognosis in multiple cancer types, and CK2 is a target for active research and testing for cancer therapy. Aspects of CK2 cellular roles and targeting in cancer are discussed in the present review, with focus on nuclear and mitochondrial functions and prostate, breast and head and neck malignancies.

Identification of high protein kinase CK2α in HPV(+) oropharyngeal squamous cell carcinoma and correlation with clinical outcomes

Background

Oropharyngeal squamous cell carcinoma (OPSCC) incidence is rising worldwide, especially human papillomavirus (HPV)-associated disease. Historically, high levels of protein kinase CK2 were linked with poor outcomes in head and neck squamous cell carcinoma (HNSCC), without consideration of HPV status. This retrospective study examined tumor CK2α protein expression levels and related clinical outcomes in a cohort of Veteran OPSCC patient tumors which were determined to be predominantly HPV(+).

Methods

Patients at the Minneapolis VA Health Care System with newly diagnosed primary OPSCC from January 2005 to December 2015 were identified. A total of 119 OPSCC patient tumors were stained for CK2α, p16 and Ki-67 proteins and E6/E7 RNA. CK2α protein levels in tumors and correlations with HPV status and Ki-67 index were assessed. Overall survival (OS) analysis was performed stratified by CK2α protein score and separately by HPV status, followed by Cox regression controlling for smoking status. To strengthen the limited HPV(−) data, survival analysis for HPV(−) HNSCC patients in the publicly available The Cancer Genome Atlas (TCGA) PanCancer RNA-seq dataset was determined for CSNK2A1.

Results

The patients in the study population were all male and had a predominant history of tobacco and alcohol use. This cohort comprised 84 HPV(+) and 35 HPV(−) tumors. CK2α levels were higher in HPV(+) tumors compared to HPV(−) tumors. Higher CK2α scores positively correlated with higher Ki-67 index. OS improved with increasing CK2α score and separately OS was significantly better for those with HPV(+) as opposed to HPV(−) OPSCC. Both remained significant after controlling for smoking status. High CSNK2A1 mRNA levels from TCGA data associated with worse patient survival in HPV(−) HNSCC.

Conclusions

High CK2α protein levels are detected in HPV(+) OPSCC tumors and demonstrate an unexpected association with improved survival in a strongly HPV(+) OPSCC cohort. Worse survival outcomes for high CSNK2A1 mRNA levels in HPV(−) HNSCC are consistent with historical data. Given these surprising findings and the rising incidence of HPV(+) OPSCC, further study is needed to understand the biological roles of CK2 in HPV(+) and HPV(−) HNSCC and the potential utility for therapeutic targeting of CK2 in these two disease states.

Abstract P199: Tenfibgen nanoencapsulated RNAi feCK2 inhibits protein kinase CK2 and induces apoptosis in feline oral squamous cell carcinomas in vivo

In an initial safety evaluation in domestic cats suffering from oral squamous cell carcinomas (FOSCC), nine cat subjects were treated IV with 5-6 doses given twice weekly of s50 RNAi feCK2 at either 2 or 20 ug/kg (Cannon et. al., Hu Gene Ther Clin Devel 28(2):80-6, 2017). Treatment was generally well tolerated. In one case, a clear drug-related Grade 3 side effect was rapid tumor death (tumor lysis) resulting in an open wound. This issue has been addressed successfully in separate mice studies with longer, lower-dose SQ regimens. Protein kinase CK2, as a promising target in oncology, plays vital roles in cell growth, proliferation, and suppression of apoptosis (Ahmed et al., Trends Cell Biol 12: 226-30, 2002). Anti-feCK2aa’ is a tumor-targeted 20 nm crystalline capsule bearing single-stranded RNAi oligos against both CK2 catalytic kinase subunits with a ligand-coated shell derived from Tenascin-C (tenfibgen). Tenascin-C is upregulated in multiple solid tumors and is present in tumors throughout their lifecycle. The capsule’s ultrasmall size enables efficient raft-mediated delivery of oligos to the perinuclear space of the target cell, and the ability to reach metastases without reliance on EPR (Unger et. al, Mol Cancer Ther 13:2018-29, 2014). Initial mechanistic work focused on changes in clinically scored IHC of the CK2a subunit in study tumors. In an effort to develop a future working hypothesis, remaining paraffin-embedded tissues were retrospectively examined for both kinase subunits of CK2 as a mixture (CK2aa’), cleaved PARP (CP, apoptosis marker) and Ago2 (critical enzyme required for RNAi drug activity). Previous work in murine models showed variation of Ago2 levels in primary human and xenograft tumors. Further, model xenograft and syngeneic tumors responded with increased Ago2 levels and drug activity upon 10 mg/ml IV priming followed by low-dose SQ treatment (Cancer Res 2016;76(14 Suppl):3746). Using confocal fluorescence microscopy, we observed that decreased post-treatment CK2aa’ and increased CP corresponded positively with clinical tumor responses while non-responders showed an inverse relationship. Examination of arrayed human HNC samples also showed a variation in Ago2 levels but premalignant oral lesions from a human chemoprevention trial did not. These observations suggest a possible future path for feline patient therapy of advanced lesions using Ago2 stratification, potential IV priming and more convenient, longer-term SQ dosing administered by feline caregivers. A path for human therapy may lie through chemoprevention with much to be learned from feline studies. Funding: University of Minnesota Clinical and Translational Sciences Award (1UL1 RR033183-01), NIH SBIR Contract HHSN26120 1300030C, N01-CN-15000, Mod#5, V.A. Merit Review research funds (BX00173 and BX003282) and NCI Award CA150182.

Citation Format: Frank G. Ondrey, Gretchen M. Unger, Claire M. Cannon, Janeen H. Trembley, BT Kren, Jaime F. Modiano, Khalil Ahmed. Tenfibgen nanoencapsulated RNAi feCK2 inhibits protein kinase CK2 and induces apoptosis in feline oral squamous cell carcinomas in vivo [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P199.

Protein kinase CK2 impact on intracellular calcium homeostasis in prostate cancer

Protein kinase CK2 plays multiple roles in cell function in normal and disease states. CK2 is elevated in numerous types of cancer cells, and CK2 suppression of apoptosis represents a key link to the cancer cell phenotype. CK2 regulation of cell survival and death involves diverse processes, and our previous work suggested that mitochondrial machinery is a key locus of this function. One of the earliest responses of prostate cells to inhibition of CK2 is a change in mitochondrial membrane potential, possibly associated with Ca²⁺ signaling. Thus, in the present work, we investigated early impact of CK2 on intracellular Ca²⁺ dynamics. Three prostate cancer (PCa) cell lines, PC3-LN4, C4-2B, and 22Rv1, were studied. PCa cells were treated with the CK2 small molecule inhibitors 4,5,6,7-tetrabrombenzotriazole and CX-4945 followed by analysis of Ca²⁺ levels in various cellular compartments over time. The results showed dose-dependent loss in cytosolic Ca²⁺ levels starting within 2 min and reaching maximal loss within 5-10 min. There was a concomitant increase in Ca²⁺ in the endoplasmic reticulum (ER) and mitochondrial compartments. The results suggest that inhibition of CK2 activity results in a rapid movement of Ca²⁺ out of the cytosol and into the ER and mitochondria, which may be among the earliest contributory factors for induction of apoptosis in cells subjected to inhibition of CK2. In cells with death-inducing levels of CK2 inhibition, total cellular Ca²⁺ levels dropped at 2 h post-treatment. These novel observations represent a potential mechanism underlying regulation of cell survival and death by CK2 activity.

Immune characteristics correlating with HSV-1 immune control and effect of squaric acid dibutyl ester on immune characteristics of subjects with frequent herpes labialis episodes

Introduction

Differences in immune characteristics, including immune gene expression by peripheral blood mononuclear cells (PBMCs), correlating with herpes labialis and good or poor immune control of herpes simplex virus type 1 (HSV‐1), and how these characteristics change after dosing with squaric acid dibutyl ester (SADBE), were investigated.

Methods

PBMCs were collected from persons positive for IgG against HSV‐1 and having frequent, infrequent, or no herpes labialis outbreaks. The PBMCs were tested for proliferation against HSV‐1 and a fungal antigen (Candida) and immune gene expression in the presence of HSV‐1 and Candida. On day 1 after blood collection the subjects with frequent outbreaks were dosed topically on the arm once with SADBE, and their PBMCs were collected and tested 8 weeks later.

Results

Those with good immune control of their HSV‐1 infection (fewer outbreaks) differ from those with poorer immune control in these ways: (1) Greater PBMC proliferation in vitro to HSV‐1, HSV‐1‐infected cell extracts, and Candida considered together (P < 0.01). (2) Higher expression of IFNG and five other immune‐related genes (P < 0.05 for each) and lower expression of IL5 and two other immune‐related genes (P < 0.05 for each) in PBMCs in vitro stimulated with HSV‐1 virus. The subjects with frequent outbreaks were treated once with SADBE, and 56 days later the PBMCs of these subjects differed from PBMCs from the same subjects taken on day 1 before treatment in exactly the same ways listed above as differences between those with good and poor immune control of HSV‐1, and at the same levels of significance.

Conclusions

Higher IFNG and lower IL5 expression by PBMCs in the presence of HSV‐1 correlate with fewer herpes labialis outbreaks, and a single topical dose of SADBE to the arm of subjects with frequent herpes labialis episodes improves immune response to HSV‐1.

CK2 targeted RNAi therapeutic delivered via malignant cell-directed tenfibgen nanocapsule: dose and molecular mechanisms of response in xenograft prostate tumors

CK2, a protein serine/threonine kinase, promotes cell proliferation and suppresses cell death. This essential-for-survival signal demonstrates elevated expression and activity in all cancers examined, and is considered an attractive target for cancer therapy. Here, we present data on the efficacy of a tenfibgen (TBG) coated nanocapsule which delivers its cargo of siRNA (siCK2) or single stranded RNA/DNA oligomers (RNAi-CK2) simultaneously targeting CK2α and α' catalytic subunits. Intravenous administration of TBG-siCK2 or TBG-RNAi-CK2 resulted in significant xenograft tumor reduction at low doses in PC3-LN4 and 22Rv1 models of prostate cancer. Malignant cell uptake and specificity in vivo was verified by FACS analysis and immunofluorescent detection of nanocapsules and PCR detection of released oligomers. Dose response was concordant with CK2αα' RNA transcript levels and the tumors demonstrated changes in CK2 protein and in markers of proliferation and cell death. Therapeutic response corresponded to expression levels for argonaute and GW proteins, which function in oligomer processing and translational repression. No toxicity was detected in non-tumor tissues or by serum chemistry. Tumor specific delivery of anti-CK2 RNAi via the TBG nanoencapsulation technology warrants further consideration of translational potential.

Evaluation of protein kinase CK2 as a therapeutic target for squamous cell carcinoma of cats

OBJECTIVE To investigate protein kinase CK2 (CK2) expression in squamous cell carcinoma (SCC) of cats and to examine effects of CK2 downregulation on in vitro apoptosis and viability in SCC. SAMPLE Biopsy specimens of oral mucosa and testis and blood samples from clinically normal cats, biopsy specimens of oral SCC from cats, and feline SCC (SCCF1) and mammary gland carcinoma (K12) cell lines. PROCEDURES Immunohistochemical labeling for CK2α was performed on biopsy specimens. Sequences of the CK2α subunit gene and CK2α' subunit gene in feline blood and feline cancer cell lines were determined by use of PCR and reverse-transcription PCR assays followed by direct Sanger sequencing. Specific small interfering RNAs (siRNAs) were developed for feline CK2α and CK2α'. The SCCF1 cells were treated with siRNA and assessed 72 hours later for CK2α and CK2α' expression and markers of apoptosis (via western blot analysis) and for viability (via 3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium assays). RESULTS CK2α was expressed in all feline oral mucosa samples and 7 of 8 oral SCC samples. Expression of CK2α and CK2α' was successfully downregulated in SCCF1 cells by use of siRNAs, which resulted in decreased viability and induction of apoptosis. CONCLUSIONS AND CLINICAL RELEVANCE In this study, CK2 appeared to be a promising therapeutic target for SCCs of cats. A possible treatment strategy for SCCs of cats would be RNA interference that targets CK2.

Therapeutic Targeting of Protein Kinase CK2 Gene Expression in Feline Oral Squamous Cell Carcinoma: A Naturally Occurring Large-Animal Model of Head and Neck Cancer

Protein kinase CK2 (CK2) is a highly promising target for cancer therapy, and anti-CK2 gene expression therapy has shown effectiveness in rodent models of human head and neck cancer (HNC). To date, there has been no large-animal model of cancer in which to further explore anti-CK2 therapies. Feline oral squamous cell carcinoma (FOSCC) has been proposed as a large-animal model for human HNC, and we have previously shown that CK2 is a rational target in FOSCC. Here we have tested the hypothesis that a novel tenfibgen-coated tumor-specific nanocapsule carrying RNA interference (RNAi) oligonucleotides targeting feline CK2α and CK2α' (TBG-RNAi-fCK2αα') would be safe in cats with FOSCC; assessment of target inhibition and tumor response were secondary aims. Nine cats were enrolled and treated at two dose levels in a 3+3 escalation. Cats received a total of six treatments with TBG-RNAi-fCK2αα'. Pre- and posttreatment, tumor and normal oral mucosa biopsies were collected to assess CK2 expression, using immunohistochemistry (IHC) preparations evaluated by light microscopy. Toxicity and tumor response were assessed on the basis of standard criteria. The most common adverse events were grade 1 or 2 weight loss and anorexia. Grade 3 tissue necrosis was seen in association with tumor response in one cat, asymptomatic grade 4 elevations in aspartate transaminase and creatine phosphokinase in one cat, and asymptomatic grade 3 hypokalemia in one cat. Of six cats with evaluable biopsies, two had a reduction in CK2 IHC score in tumors after treatment. Four cats had progressive disease during the study period, three had stable disease, one had partial response, and response could not be evaluated in one cat. We conclude that the drug appeared safe and that there is some evidence of efficacy in FOSCC. Further investigation regarding dosing, schedule, target modulation, toxicity, and efficacy in a larger group of cats is warranted and may inform future clinical studies in human head and neck cancer.

CK2 Molecular Targeting-Tumor Cell-Specific Delivery of RNAi in Various Models of Cancer

Protein kinase CK2 demonstrates increased protein expression relative to non-transformed cells in the majority of cancers that have been examined. The elevated levels of CK2 are involved in promoting not only continued proliferation of cancer cells but also their resistance to cell death; thus, CK2 has emerged as a plausible target for cancer therapy. Our focus has been to target CK2 catalytic subunits at the molecular level using RNA interference (RNAi) strategies to achieve their downregulation. The delivery of oligonucleotide therapeutic agents warrants that they are protected and are delivered specifically to cancer cells. The latter is particularly important since CK2 is a ubiquitous signal that is essential for survival. To achieve these goals, we have developed a nanocapsule that has the properties of delivering an anti-CK2 RNAi therapeutic cargo, in a protected manner, specifically to cancer cells. Tenfibgen (TBG) is used as the ligand to target tenascin-C receptors, which are elevated in cancer cells. This strategy is effective for inhibiting growth and inducing death in several types of xenograft tumors, and the nanocapsule elicits no safety concerns in animals. Further investigation of this therapeutic approach for its translation is warranted.

Protein kinase CK2 inhibition induces cell death via early impact on mitochondrial function

CK2 (official acronym for casein kinase 2 or II) is a potent suppressor of apoptosis in response to diverse apoptotic stimuli-thus its molecular downregulation or activity inhibition results in potent induction of cell death. CK2 downregulation is known to impact mitochondrial apoptotic circuitry but the underlying mechanism(s) remain unclear. Utilizing prostate cancer cell lines subjected to CK2-specific inhibitors which cause loss of cell viability, we have found that CK2 inhibition in cells causes rapid early decrease in mitochondrial membrane potential (Δψm). Cells treated with the CK2 inhibitors TBB (4,5,6,7-tetrabromobenzotriazole) or TBCA (tetrabromocinnamic acid) demonstrate changes in Δψm which become apparent within 2 h, that is, significantly prior to evidence of activation of other mitochondrial apoptotic signals whose temporal expression ensues subsequent to loss of Δψm. Further, we have demonstrated the presence of CK2 in purified mitochondria and it appears that the effect on Δψm evoked by inhibition of CK2 may involve mitochondrial localized CK2. Results also suggest that alterations in Ca(2+) signaling may be involved in the CK2 mediated regulation of Δψm and mitochondrial permeability. Thus, we propose that a key mechanism of CK2 impact on mitochondrial apoptotic circuitry and cell death involves early loss of Δψm which may be a primary trigger for apoptotic signaling and cell death resulting from CK2 inhibition.

Preclinical evaluation of cyclin dependent kinase 11 and casein kinase 2 survival kinases as RNA interference targets for triple negative breast cancer therapy

Introduction

Targeted therapies for aggressive breast cancers like triple negative breast cancer (TNBC) are needed. The use of small interfering RNAs (siRNAs) to disable expression of survival genes provides a tool for killing these cancer cells. Cyclin dependent kinase 11 (CDK11) is a survival protein kinase that regulates RNA transcription, splicing and mitosis. Casein kinase 2 (CK2) is a survival protein kinase that suppresses cancer cell death. Eliminating the expression of these genes has potential therapeutic utility for breast cancer.

Methods

Expression levels of CDK11 and CK2 mRNAs and associated proteins were examined in breast cancer cell lines and tissue arrays. RNA expression levels of CDC2L1, CDC2L2, CCNL1, CCNL2, CSNK2A1, CSNK2A2, and CSNK2B genes in breast cancer subtypes were analyzed. Effects following transfection of siRNAs against CDK11 and CK2 in cultured cells were examined by viability and clonal survival assays and by RNA and protein measures. Uptake of tenfibgen (TBG) nanocapsules by TNBC cells was analyzed by fluorescence-activated cell sorting. TBG nanocapsules delivered siRNAs targeting CDK11 or CK2 in mice carrying TNBC xenograft tumors. Transcript cleavage and response parameters were evaluated.

Results

We found strong CDK11 and CK2 mRNA and protein expression in most human breast cancer cells. Immunohistochemical analysis of TNBC patient tissues showed 100% of tumors stained positive for CDK11 with high nuclear intensity compared to normal tissue. The Cancer Genome Atlas analysis comparing basal to other breast cancer subtypes and to normal breast revealed statistically significant differences. Down-regulation of CDK11 and/or CK2 in breast cancer cells caused significant loss of cell viability and clonal survival, reduced relevant mRNA and protein expression, and induced cell death changes. TBG nanocapsules were taken up by TNBC cells both in culture and in xenograft tumors. Treatment with TBG- siRNA to CDK11 or TBG- siRNA to CK2αα’ nanocapsules induced appropriate cleavage of CDK11 and CK2α transcripts in TNBC tumors, and caused MDA-MB-231 tumor reduction, loss of proliferation, and decreased expression of targeted genes.

Conclusions

CDK11 and CK2 expression are individually essential for breast cancer cell survival, including TNBC. These genes serve as promising new targets for therapeutic development in breast cancer.

Tenfibgen ligand nanoencapsulation delivers bi-functional anti-CK2 RNAi oligomer to key sites for prostate cancer targeting using human xenograft tumors in mice

Protected and specific delivery of nucleic acids to malignant cells remains a highly desirable approach for cancer therapy. Here we present data on the physical and chemical characteristics, mechanism of action, and pilot therapeutic efficacy of a tenfibgen (TBG)-shell nanocapsule technology for tumor-directed delivery of single stranded DNA/RNA chimeric oligomers targeting CK2αα' to xenograft tumors in mice. The sub-50 nm size TBG nanocapsule (s50-TBG) is a slightly negatively charged, uniform particle of 15 - 20 nm size which confers protection to the nucleic acid cargo. The DNA/RNA chimeric oligomer (RNAi-CK2) functions to decrease CK2αα' expression levels via both siRNA and antisense mechanisms. Systemic delivery of s50-TBG-RNAi-CK2 specifically targets malignant cells, including tumor cells in bone, and at low doses reduces size and CK2-related signals in orthotopic primary and metastatic xenograft prostate cancer tumors. In conclusion, the s50-TBG nanoencapsulation technology together with the chimeric oligomer targeting CK2αα' offer significant promise for systemic treatment of prostate malignancy.

Mechanism and efficacy of sub-50-nm tenfibgen nanocapsules for cancer cell-directed delivery of anti-CK2 RNAi to primary and metastatic squamous cell carcinoma

Improved survival for patients with head and neck cancers (HNC) with recurrent and metastatic disease warrants that cancer therapy is specific, with protected delivery of the therapeutic agent to primary and metastatic cancer cells. A further objective should be that downregulation of the intracellular therapy target leads to cell death without compensation by an alternate pathway. To address these goals, we report the utilization of a sub-50-nm tenfibgen (s50-TBG) nanocapsule that delivers RNAi oligonucleotides directed against the essential survival signal protein kinase CK2 (RNAi-CK2) in a cancer cell-specific manner. We have evaluated mechanism and efficacy of using s50-TBG-RNAi-CK2 nanocapsules for therapy of primary and metastatic head and neck squamous cell carcinoma (HNSCC). s50-TBG nanocapsules enter cancer cells via the lipid raft/caveolar pathway and deliver their cargo (RNAi-CK2) preferentially to malignant but not normal tissues in mice. Our data suggest that RNAi-CK2, a unique single-stranded oligonucleotide, co-opts the argonaute 2/RNA-induced silencing complex pathway to target the CK2αα' mRNAs. s50-TBG-RNAi-CK2 inhibited cell growth corresponding with reduced CK2 expression in targeted tumor cells. Treatment of three xenograft HNSCC models showed that primary tumors and metastases responded to s50-TBG-RNAi-CK2 therapy, with tumor shrinkage and 6-month host survival that was achieved at relatively low doses of the therapeutic agent without any adverse toxic effect in normal tissues in the mice. We suggest that our nanocapsule technology and anti-CK2 targeting combine into a therapeutic modality with a potential of significant translational promise.

Tenfibgen-DMAT Nanocapsule Delivers CK2 Inhibitor DMAT to Prostate Cancer Xenograft Tumors Causing Inhibition of Cell Proliferation

CK2 is a master regulator protein kinase which demonstrates heightened expression in diverse cancer types and is considered a promising target for therapy. Given its ubiquitous expression and potent influence on cell survival, cancer cell-directed targeting of the CK2 signal is an important factor for development of an anti-CK2 therapeutic. We previously reported on the malignant cell specificity and effect on CK2 signaling of a tenfibgen (TBG) based nanocapsule for delivery of the CK2 small molecule inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) in cultured prostate cancer cells. Here we tested the ability of TBG-DMAT to affect the growth of prostate xenograft tumors in mice. Our results show that treatment of PC3-LN4 xenograft tumors with TBG-DMAT caused loss of proliferative Ki-67 signal as well as Nuclear Factor-kappa B (NF-κB) expression in the tumors. Further, the TBG-DMAT nanocapsule was detected in tumors and not in liver or testis. In conclusion, TBG-based nanocapsule delivery of anti-CK2 small molecule drugs holds significant promise for treatment of prostate cancer.

β-globin matrix attachment region improves stable genomic expression of the Sleeping Beauty transposon

The liver is an attractive target for gene therapy due to its extensive capability for protein production and the numerous diseases resulting from a loss of gene function it normally provides. The Sleeping Beauty Transposon (SB-Tn)(1) system is a non-viral vector capable of delivering and mediating therapeutic transgene(s) insertion into the host genome for long-term expression. A current challenge for this system is the low efficiency of integration of the transgene. In this study we use a human hepatoma cell line (HuH-7) and primary human blood outgrowth endothelial cells (BOECs) to test vectors containing DNA elements to enhance transposition without integrating themselves. We employed the human β-globin matrix attachment region (MAR) and the Simian virus 40 (SV40) nuclear translocation signal to increase the percent of HuH-7 cells persistently expressing a GFP::Zeo reporter construct by ∼50% for each element; while combining both did not show an additive effect. Interestingly, both elements together displayed an additive effect on the number of insertion sites, and in BOECs the SV40 alone appeared to have an inhibitory effect on transposition. In long-term cultures the loss of plasmid DNA, transposase expression and mapping of insertion sites demonstrated bona fide transposition without episomal expression. These results show that addition of the β-globin MAR and potentially other elements to the backbone of SB-Tn system can enhance transposition and expression of therapeutic transgenes. These findings may have a significant influence on the use of SB transgene delivery to liver for the treatment of a wide variety of disorders.

Nanoencapsulated anti-CK2 small molecule drug or siRNA specifically targets malignant cancer but not benign cells

CK2, a pleiotropic Ser/Thr kinase, is an important target for cancer therapy. We tested our novel tenfibgen-based nanocapsule for delivery of the inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) and an siRNA directed against both CK2α and α' catalytic subunits to prostate cancer cells. We present data on the TBG nanocapsule itself and on CK2 inhibition or downregulation in treated cells, including effects on Nuclear Factor-kappa B (NF-κB) p65. By direct comparison of two CK2-directed cargos, our data provide proof that the TBG encapsulation design for delivery of drugs specifically to cancer cells has strong potential for small molecule- and nucleic acid-based cancer therapy.

Genomewide microRNA down-regulation as a negative feedback mechanism in the early phases of liver regeneration

The liver is one of the few organs that have the capacity to regenerate in response to injury. We carried out genomewide microRNA (miRNA) microarray studies during liver regeneration in rats after 70% partial hepatectomy (PH) at early and mid time points to more thoroughly understand their role. At 3, 12, and 18 hours post-PH ∼40% of the miRNAs tested were up-regulated. Conversely, at 24 hours post-PH, ∼70% of miRNAs were down-regulated. Furthermore, we established that the genomewide down-regulation of miRNA expression at 24 hours was also correlated with decreased expression of genes, such as Rnasen, Dgcr8, Dicer, Tarbp2, and Prkra, associated with miRNA biogenesis. To determine whether a potential negative feedback loop between miRNAs and their regulatory genes exists, 11 candidate miRNAs predicted to target the above-mentioned genes were examined and found to be up-regulated at 3 hours post-PH. Using reporter and functional assays, we determined that expression of these miRNA-processing genes could be regulated by a subset of miRNAs and that some miRNAs could target multiple miRNA biogenesis genes simultaneously. We also demonstrated that overexpression of these miRNAs inhibited cell proliferation and modulated cell cycle in both Huh-7 human hepatoma cells and primary rat hepatocytes. From these observations, we postulated that selective up-regulation of miRNAs in the early phase after PH was involved in the priming and commitment to liver regeneration, whereas the subsequent genomewide down-regulation of miRNAs was required for efficient recovery of liver cell mass.

CONCLUSION

Our data suggest that miRNA changes are regulated by negative feedback loops between miRNAs and their regulatory genes that may play an important role in the steady-state regulation of liver regeneration.

Systemic administration of antisense oligonucleotides simultaneously targeting CK2α and α' subunits reduces orthotopic xenograft prostate tumors in mice

CK2 is a highly conserved, ubiquitous, signal responsive protein serine/threonine kinase. CK2 promotes cell proliferation and suppresses apoptosis, and increased CK2 expression is observed in all cancers examined. We previously reported that direct injection of antisense (AS) CK2α phosphorothioate oligonucleotides (PTO) into xenograft prostate tumors in mice significantly reduced tumor size. Downregulation of CK2α in tumor cells in vivo appeared to result in overexpression of CK2α' protein. This suggested that in cancer cells downregulation of CK2α might be compensated by CK2α' in vivo, prompting us to design a bispecific (bs) AS PTO (bs-AS-CK2) targeting both catalytic subunits. bs-AS-CK2 reduced CK2α and α' protein expression, decreased cell proliferation, and induced apoptosis in cultured cells. Biodistribution studies of administered bs-AS-CK2 oligonucleotide demonstrated its presence in orthotopic prostate xenograft tumors. High dose injections of bs-AS-CK2 resulted in no damage to normal liver or prostate, but induced extensive cell death in tumor tissue. Intraperitoneal treatment with bs-AS-CK2 PTO decreased orthotopic tumor size and downregulated both CK2 mRNA and protein expression. Tumor reduction was accomplished using remarkably low doses and was improved by dividing the dose using a multi-day schedule. Decreased expression of the key signaling pathway proteins NF-κB p65 and AKT was also observed. We propose that the molecular downregulation of CK2 through bispecific targeting of the two catalytic subunits may be uniquely useful for therapeutic elimination of tumors.

Identification of microRNAs during rat liver regeneration after partial hepatectomy and modulation by ursodeoxycholic acid

New gene regulation study tools such as microRNA (miRNA or miR) analysis may provide unique insights into the remarkable ability of the liver to regenerate. In addition, we have previously shown that ursodeoxycholic acid (UDCA) modulates mRNA levels during liver regeneration. Bile acids are also homeotrophic sensors of functional hepatic capacity. The present study was designed to determine whether miRNAs are modulated in rats following 70% partial hepatectomy (PH) and elucidate the role of UDCA in regulating miRNA expression during liver regeneration (LR). Total RNA was isolated from livers harvested at 3-72 h following 70% PH or sham operations, from both 0.4% (wt/wt) UDCA and control diet-fed animals. By using a custom microarray platform we found that several miRNAs are significantly altered after PH by >1.5-fold, including some previously described as modulators of cell proliferation, differentiation, and death. In particular, expression of miR-21 was increased after PH. Functional modulation of miR-21 in primary rat hepatocytes increased cell proliferation and viability. Importantly, UDCA was a strong inducer of miR-21 both during LR and in cultured HepG2 cells. In fact, UDCA feeding appeared to induce a sustained increase of proliferative miRNAs observed at early time points after PH. In conclusion, miRNAs, in particular miR-21, may play a significant role in modulating proliferation and cell cycle progression genes after PH. miR-21 is additionally induced by UDCA in both regenerating rat liver and in vitro, which may represent a new mechanism behind UDCA biological functions.

Emergence of protein kinase CK2 as a key target in cancer therapy

Protein kinase CK2, a protein serine/threonine kinase, plays a global role in activities related to cell growth, cell death, and cell survival. CK2 has a large number of potential substrates localized in diverse locations in the cell including, for example, NF-kappaB as an important downstream target of the kinase. In addition to its involvement in cell growth and proliferation it is also a potent suppressor of apoptosis, raising its key importance in cancer cell phenotype. CK2 interacts with diverse pathways which illustrates the breadth of its impact on the cellular machinery of both cell growth and cell death giving it the status of a "master regulator" in the cell. With respect to cancer, CK2 has been found to be dysregulated in all cancers examined demonstrating increased protein expression levels and nuclear localization in cancer cells compared with their normal counterparts. We originally proposed CK2 as a potentially important target for cancer therapy. Given the ubiquitous and essential for cell survival nature of the kinase, an important consideration would be to target it specifically in cancer cells while sparing normal cells. Towards that end, our design of a tenascin based sub-50 nm (i.e., less than 50 nm size) nanocapsule in which an anti-CK2 therapeutic agent can be packaged is highly promising because this formulation can specifically deliver the cargo intracellularly to the cancer cells in vivo. Thus, appropriate strategies to target CK2 especially by molecular approaches may lead to a highly feasible and effective approach to eradication of a given cancer.

High-level genomic integration, epigenetic changes, and expression of sleeping beauty transgene

Sleeping Beauty transposon (SB-Tn) has emerged as an important nonviral vector for integrating transgenes into mammalian genomes. We report here a novel dual fluorescent reporter cis SB-Tn system that permitted nonselective fluorescent-activated cell sorting for SB-Tn-transduced K562 erythroid cells. Using an internal ribosome entry site element, the green fluorescent protein (eGFP) was linked to the SB10 transposase gene as an indirect marker for the robust expression of SB10 transposase. Flourescence-activated cell sorting (FACS) by eGFP resulted in significant enrichment (>60%) of cells exhibiting SB-Tn-mediated genomic insertions and long-term expression of a DsRed transgene. The hybrid erythroid-specific promoter of DsRed transgene was verified in erythroid or megakaryocyte differentiation of K562 cells. Bisulfite-mediated genomic analyses identified different DNA methylation patterns between DsRed(+) and DsRed(-) cell clones, suggesting a critical role in transgene expression. Moreover, although the host genomic copy of the promoter element showed no CpG methylation, the same sequence carried by the transgene was markedly hypermethylated. Additional evidence also suggested a role for histone deacetylation in the regulation of DsRed transgene. The presence of SB transgene affected the expression of neighboring host genes at distances >45 kb. Our data suggested that a fluorescent reporter cis SB-Tn system can be used to enrich mammalian cells harboring SB-mediated transgene insertions. The observed epigenetic changes also demonstrated that transgenes inserted by SB could be selectively modified by endogenous factors. In addition, long-range activation of host genes must now be recognized as a potential consequence of an inserted transgene cassette containing enhancer elements.

Polysome trafficking of transcripts and microRNAs in regenerating liver after partial hepatectomy

Liver regeneration after 70% partial hepatectomy (PH) in rats induces >95% of hepatocytes to undergo two rounds of semisynchronous cell replication. Gene expression is controlled primarily by posttranscriptional processing, including changes in mRNA stability. However, the translational activity of a specific mRNA can also be modulated after PH, resulting in significant uncoupling of protein and transcript levels relative to quiescent liver for many genes including c-myc and p53. Although the precise mechanism by which this uncoupling occurs is unknown, the polysomal association of mRNA and microRNA (miRNA) can significantly modulate rate of decay as well as translational activity. Thus we characterized the association of c-myc and p53 mRNAs and miRNAs in free and cytoskeleton- and membrane-bound polysome populations 3, 6, and 24 h after PH. The transcripts for c-myc and p53 were differentially distributed in the three discrete polysome populations, and this was dramatically modulated during liver regeneration. Nascent polysome-associated p53 and c-myc proteins were also differentially expressed in the free and cytoskeleton- and membrane-bound polysomes and significantly uncoupled from transcript levels relative to nonresected liver. At least 85 miRNAs were associated with the three polysome populations, and their abundance and distribution changed significantly during liver regeneration. These data suggest that posttranscriptional control of c-myc and p53 protein expression is associated with the translocation of transcripts between the different polyribosomes. The alteration of expression for the same transcript in different polysome populations may, in part, be due to the action of miRNAs.

MicroRNA-143 reduces viability and increases sensitivity to 5-fluorouracil in HCT116 human colorectal cancer cells

MicroRNAs are aberrantly expressed in cancer; microRNA-143 (miR-143) is down-regulated in colon cancer. HCT116 human colorectal cancer cells were used to investigate the biological role of miR-143. Transient miR-143 overexpression resulted in an approximate 60% reduction in cell viability. In addition, stable miR-143 overexpressing cells were selected with G418 and exposed to 5-fluorouracil. Increased stable expression of miR-143 was associated with decreased viability and increased cell death after exposure to 5-fluorouracil. These changes were associated with increased nuclear fragmentation and caspase -3, -8 and -9 activities. In addition, extracellular-regulated protein kinase 5, nuclear factor-kappaB and Bcl-2 protein expression was down-regulated by miR-143, and further reduced by exposure to 5-fluorouracil. In conclusion, miR-143 modulates the expression of key proteins involved in the regulation of cell proliferation, death and chemotherapy response. In addition, miR-143 increases the sensitivity of colon cancer cells to 5-fluorouracil, probably acting through extracellular-regulated protein kinase 5/nuclear factor-kappaB regulated pathways. Collectively, the data obtained in the present study suggest anti-proliferative, chemosensitizer and putative pro-apoptotic roles for miR-143 in colon cancer.

Long-term reduction of jaundice in Gunn rats by nonviral liver-targeted delivery of Sleeping Beauty transposon

Asialoglycoprotein receptor (ASGPR)-mediated endocytosis has been used to target genes to hepatocytes in vivo. However, the level and duration of transgene expression have been low because of lysosomal translocation and degradation of the DNA and lack of its integration into the host genome. In this study we packaged the DNA of interest in proteoliposomes containing the fusogenic galactose-terminated F-glycoprotein of the Sendai virus (FPL) for targeted delivery to hepatocytes. After the FPL binds to ASGPR on the hepatocyte surface, fusogenic activity of the F-protein delivers the DNA into the cytosol, bypassing the endosomal pathway. For transgene integration we designed plasmids containing one transcription unit expressing the Sleeping Beauty transposase (SB) and another expressing human uridinediphosphoglucuronate glucuronosyltransferase-1A1 (pSB-hUGT1A1). The latter was flanked by inverted/direct repeats that are substrates of SB. In cell culture, FPL-mediated delivery of the E. coli beta-galactosidase gene (LacZ) resulted in transduction of ASGPR-positive cells (rat hepatocytes or Hepa1 cell line), but not of ASGPR-negative 293 cells. Intravenous injection of the FPL-entrapped pSB-hUGT1A1 (4-8 microg/day, 1-4 doses) into UGT1A1-deficient hyperbilirubinemic Gunn rats (model of Crigler-Najjar syndrome type 1) resulted in hUGT1A1 expression in 5%-10% of hepatocytes, but not in other cell types. Serum bilirubin levels declined by 30% +/- 4% in 2 weeks and remained at that level throughout the 7-month study duration. With histidine containing FPL, serum bilirubin was reduced by 40% +/- 5%, and bilirubin glucuronides were excreted into bile. No antibodies were detectable in the recipient rats against the F-protein or human UGT1A1.

CONCLUSION

FPL is an efficient hepatocyte-targeted gene delivery platform in vivo that warrants further exploration toward clinical application.

Evaluation of a new high-dimensional miRNA profiling platform

Background

MicroRNAs (miRNAs) are a class of approximately 22 nucleotide long, widely expressed RNA molecules that play important regulatory roles in eukaryotes. To investigate miRNA function, it is essential that methods to quantify their expression levels be available.

Methods

We evaluated a new miRNA profiling platform that utilizes Illumina's existing robust DASL chemistry as the basis for the assay. Using total RNA from five colon cancer patients and four cell lines, we evaluated the reproducibility of miRNA expression levels across replicates and with varying amounts of input RNA. The beta test version was comprised of 735 miRNA targets of Illumina's miRNA profiling application.

Results

Reproducibility between sample replicates within a plate was good (Spearman's correlation 0.91 to 0.98) as was the plate-to-plate reproducibility replicates run on different days (Spearman's correlation 0.84 to 0.98). To determine whether quality data could be obtained from a broad range of input RNA, data obtained from amounts ranging from 25 ng to 800 ng were compared to those obtained at 200 ng. No effect across the range of RNA input was observed.

Conclusion

These results indicate that very small amounts of starting material are sufficient to allow sensitive miRNA profiling using the Illumina miRNA high-dimensional platform. Nonlinear biases were observed between replicates, indicating the need for abundance-dependent normalization. Overall, the performance characteristics of the Illumina miRNA profiling system were excellent.

Blood Outgrowth Endothelial Cells as a Vehicle for Transgene Expression of Hepatocyte-Secreted Proteins viaSleeping Beauty

The therapeutic use of autologous cells with the capacity for extensive in vitro expansion and manipulation prior to host administration has been an area of significant investigation over the last decade. Blood outgrowth endothelial cells (BOECs) are derived from the circulation and exhibit proliferative growth, in vivo engraftment, and survival characteristics for long-term expression of endogenously secreted proteins, such as factor VIII (FVIII). The authors describe a modified method for the isolation, culture, and expansion of these cells that is readily accomplished using standard laboratory methods. Using a commercially available transfection reagent, approximately 30% of these primary cells can be routinely transfected with the nonviral Sleeping Beauty transposon for long-term, stable transgene expression. Moreover, the results indicate that these cells have the ability to secrete functionally active proteins that are synthesized endogenously by hepatocytes and require post-translational modification including alpha1-antitrypsin and clotting factors VII and IX. This, coupled with their notably long half-life of years, suggests that these cells may provide an appropriate vehicle for secretion of a variety of proteins produced by different cell types in vivo. Thus, BOECs have the potential to provide clinically relevant secreted proteins for diseases other than those of endothelial origin.

Nanocapsule-delivered Sleeping Beauty mediates therapeutic Factor VIII expression in liver sinusoidal endothelial cells of hemophilia A mice

Liver sinusoidal endothelial cells are a major endogenous source of Factor VIII (FVIII), lack of which causes the human congenital bleeding disorder hemophilia A. Despite extensive efforts, gene therapy using viral vectors has shown little success in clinical hemophilia trials. Here we achieved cell type-specific gene targeting using hyaluronan- and asialoorosomucoid-coated nanocapsules, generated using dispersion atomization, to direct genes to liver sinusoidal endothelial cells and hepatocytes, respectively. To highlight the therapeutic potential of this approach, we encapsulated Sleeping Beauty transposon expressing the B domain-deleted canine FVIII in cis with Sleeping Beauty transposase in hyaluronan nanocapsules and injected them intravenously into hemophilia A mice. The treated mice exhibited activated partial thromboplastin times that were comparable to those of wild-type mice at 5 and 50 weeks and substantially shorter than those of untreated controls at the same time points. Further, plasma FVIII activity in the treated hemophilia A mice was nearly identical to that in wild-type mice through 50 weeks, while untreated hemophilia A mice exhibited no detectable FVIII activity. Thus, Sleeping Beauty transposon targeted to liver sinusoidal endothelial cells provided long-term expression of FVIII, without apparent antibody formation, and improved the phenotype of hemophilia A mice.

MicroRNAs identified in highly purified liver-derived mitochondria may play a role in apoptosis

MicroRNAs (miRNAs) are a class of small approximately 22 nt noncoding (nc) RNAs that regulate gene expression post-transcriptionally by direct binding to target sites on mRNAs. They comprise more than 1,000 novel species in mammalian cells and exert their function by modulating gene expression through several different mechanisms, including translational inhibition, and/or degradation of target mRNAs. Mitochondria maintain and express their own genome, which is distinct from the nuclear transcriptional and translational apparatus. Thus, they provide a potential site for miRNA mediated post-transcriptional regulation. To determine whether they maintain a unique miRNA population, we examined the miRNA profile from highly purified and RNase treated mitochondria from adult rat liver. Fifteen miRNAs were identified by microarray analysis of which, five were confirmed by TaqMan 5'nuclease assays using rat specific probes. Functional analysis of the miRNAs indicated that they were not targeted to the mitochondrial genome nor were they complementary to nuclear RNAs encoding mitochondrial proteins. Rather, the mitochondria-associated miRNAs appear to be involved in the expression of genes associated with apoptosis, cell proliferation, and differentiation. Given the central role that mitochondria play in apoptosis, the results suggest that they might serve as reservoirs of select miRNAs that may modulate these processes in a coordinate fashion.

Administration of tauroursodeoxycholic acid (TUDCA) reduces apoptosis following myocardial infarction in rat

Black bear bile has been used in traditional Chinese medicine to treat liver and eye related illnesses for centuries. A major constituent of bile is ursodeoxycholic acid (UDCA). Recent analysis of the cellular effects of UDCA and its taurine conjugate tauroursodeoxycholic acid (TUDCA) have demonstrated their antiapoptotic properties through regulation of Bcl-2 family and survival signaling proteins (Bax, Bad, phosphatidylinositol-3-kinase). In this study, we tested the hypothesis that TUDCA administered to rats prior to a myocardial infarction (MI) would exhibit anti-apoptotic effects and improve cardiac function. Prior to ligation of the left anterior descending (LAD) coronary artery, TUDCA (50 mg/ml, 400 mg/kg, IV) or PBS was administered to rats. Animals were sacrificed 24 hours after ligation for terminal transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) and caspase-3 activity to assess apoptosis. Additional TUDCA or PBS treated rats underwent pre-operative,1 and 4 week transthoracic ultrasounds to assess heart function by quantification of shortening fraction (SF) and infarct area. TUNEL labeling of the cardiac tissue revealed a significant reduction in apoptotic cells in rats given TUDCA prior to ischemic injury (p = 0.05). In support of reducing apoptosis, caspase-3 activity in the TUDCA treated animals also decreased (p = 0.02). By 4 weeks, a significantly smaller infarct area was present in the TUDCA group compared to the PBS group (0.05 vs. 0.13 cm(2), p = NS) and there was also an improvement in SF. The results provide evidence for TUDCA as a viable treatment for reducing apoptosis in a model of myocardial infarction. Additional studies will distinguish the functional result of improved cell survival following infarction, suggesting the potential for clinical application of this anti-apoptotic drug in treatment of acute MI.

Differential regulation of cyclin D1 and cell death by bile acids in primary rat hepatocytes

Ursodeoxycholic (UDCA) and tauroursodeoxycholic (TUDCA) acids modulate apoptosis and regulate cell-cycle effectors, including cyclin D1. In contrast, deoxycholic acid (DCA) induces cell death and cyclin D1. In this study, we explored the role of cyclin D1 in DCA-induced toxicity and further elucidated the antiapoptotic function of UDCA and TUDCA in primary rat hepatocytes. Cells were incubated with DCA and with or without UDCA or TUDCA for 8-30 h. In addition, hepatocytes were transfected with either an adenovirus expressing cyclin D1 or with a cyclin D1 reporter plasmid with or without bile acids. Finally, cells were cotransfected with short interfering RNA targeting p53. Unlike DCA, both UDCA and TUDCA reduced cyclin D1 expression and transcriptional activation, confirming our previous DNA microarray data. Furthermore, UDCA and TUDCA prevented DCA-induced cyclin D1 and cell death. Cyclin D1 overexpression increased DCA-induced Bax translocation, cytochrome c release, and apoptosis. However, UDCA and TUDCA were less efficient at decreasing cyclin D1 levels as well as DCA-induced changes with overexpression. Finally, after p53 silencing, the effects of cyclin D1 overexpression were almost completely abrogated, whereas UDCA and TUDCA cytoprotective potential was reestablished. In conclusion, cyclin D1 is a relevant player in modulating apoptosis by bile acids, in part through a p53-dependent mechanism.

Erythroid-specific expression of beta-globin by the sleeping beauty transposon for Sickle cell disease

Sickle cell disease (SCD) results predominately from a single monogenic mutation that affects thousands of individuals worldwide. Gene therapy approaches have focused on using viral vectors to transfer wild-type beta- or gamma-globin transgenes into hematopoietic stem cells for long-term expression of the recombinant globins. In this study, we investigated the use of a novel nonviral vector system, the Sleeping Beauty (SB) transposon (Tn) to insert a wild-type beta-globin expression cassette into the human genome for sustained expression of beta-globin. We initially constructed a beta-globin expression vector composed of the hybrid cytomegalovirus (CMV) enhancer chicken beta-actin promoter (CAGGS) and full-length beta-globin cDNA, as well as truncated forms lacking either the 3' or 3' and 5' untranslated regions (UTRs), to optimize expression of beta-globin. Beta-globin with its 5' UTR was efficiently expressed from its cDNA in K-562 cells induced with hemin. However, expression was constitutive and not erythroid-specific. We then constructed cis SB-Tn-beta-globin plasmids using a minimal beta-globin gene driven by hybrid promoter IHK (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human alphaLCR, ankyrin-1 promoter), IHbetap (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human alphaLCR, beta-globin promoter), or HS3betap (HS3 core element from human betaLCR, beta-globin promoter) to establish erythroid-specific expression of beta-globin. Stable genomic insertion of the minimal gene and expression of the beta-globin transgene for >5 months at a level comparable to that of the endogenous gamma-globin gene were achieved using a SB-Tn beta-globin cis construct. Interestingly, erythroid-specific expression of beta-globin driven by IHK was regulated primarily at the translational level, in contrast to post-transcriptional regulation in non-erythroid cells. The SB-Tn system is a promising nonviral vector for efficient genomic insertion conferring stable, persistent erythroid-specific expression of beta-globin.

Sleeping Beauty transposition in the mouse genome is associated with changes in DNA methylation at the site of insertion

The Sleeping Beauty (SB) transposon (Tn) system is a nonviral gene delivery tool that has widespread application for transfer of therapeutic genes into the mammalian genome. To determine its utility as a gene delivery system, it was important to assess the epigenetic modifications associated with SB insertion into the genome and potential inactivation of the transgene. This study investigated the DNA methylation pattern of an SB Tn as well as the flanking genomic region at insertion sites in the mouse genome. The ubiquitous ROSA26 promoter and an initial part of the eGFP coding sequence in the SB Tn exhibited high levels of CpG methylation in transgenic mouse lines, irrespective of the chromosomal loci of the insertion sites. In contrast, no detectable CpG methylation in the endogenous mouse ROSA26 counterpart was observed in the same animals. Furthermore, significant hypomethylation was detected in neighboring chromosomal sequences of two unique SB Tn insertions compared to wild-type patterns. Taken together, these results suggest that SB Tn insertions into the mouse genome can be discriminated by DNA methylation machinery from an identical endogenous DNA sequence and can profoundly alter the DNA methylation status of the transgene cargo as well as flanking host genomic regions.

DNA methylation of Sleeping Beauty with transposition into the mouse genome

The Sleeping Beauty transposon is a recently developed non-viral vector that can mediate insertion of transgenes into the mammalian genome. Foreign DNA elements that are introduced tend to invoke a host-defense mechanism resulting in epigenetic changes, such as DNA methylation, which may induce transcriptional inactivation of mammalian genes. To assess potential epigenetic modifications associated with Sleeping Beauty transposition, we investigated the DNA methylation pattern of transgenes inserted into the mouse genome as well as genomic regions flanking the insertion sites with bisulfite-mediated genomic sequencing. Transgenic mouse lines were created with two different Sleeping Beauty transposons carrying either the Agouti or eGFP transgene. Our results showed that DNA methylation in the keratin-14 promoter and Agouti transgene were negligible. In addition, two different genomic loci flanking the Agouti insertion site exhibited patterns of DNA methylation similar to wild-type mice. In contrast, high levels of DNA methylation were observed in the eGFP transgene and its ROSA26 promoter. These results indicate that transposition via Sleeping Beauty into the mouse genome may result in a significant level of de novo DNA methylation. This may depend on a number of different factors including the cargo DNA sequence, chromosomal context of the insertion site, and/or host genetic background.

Nuclear translocation of UDCA by the glucocorticoid receptor is required to reduce TGF-beta1-induced apoptosis in rat hepatocytes

Ursodeoxycholic acid (UDCA) inhibits classical mitochondrial pathways of apoptosis by either directly stabilizing mitochondrial membranes or modulating specific upstream targets. Furthermore, UDCA regulates apoptosis-related genes from transforming growth factor beta1 (TGF-beta1)-induced hepatocyte apoptosis by a nuclear steroid receptor (NSR)-dependent mechanism. In this study, we further investigated the potential role of the glucocorticoid receptor (GR) in the anti-apoptotic function of UDCA. Our results with short interference RNA (siRNA) technology confirmed that UDCA significantly reduces TGF-beta1-induced apoptosis of primary rat hepatocytes through a GR-dependent effect. Immunoprecipitation assays and confocal microscopy showed that UDCA enhanced free GR levels with subsequent GR nuclear translocation. Interestingly, when a carboxy-terminus deleted form of GR was used, UDCA no longer increased free GR and/or GR translocation, nor did it protect against TGF-beta1-induced apoptosis. In co-transfection experiments with GR response element reporter and overexpression constructs, UDCA did not enhance the transactivation of GR with TGF-beta1. Finally, using a fluorescently labeled UDCA molecule, the bile acid appeared diffuse in the cytosol but was aggregated in the nucleus of hepatocytes. Both siRNA assays and transfection experiments with either wild-type or mutant forms of GR showed that nuclear trafficking occurs through a GR-dependent mechanism. In conclusion, these results further clarify the anti-apoptotic mechanism(s) of UDCA and suggest that GR is crucial for the nuclear translocation of this bile acid for reducing apoptosis.

Tumor-induced mechanical hyperalgesia involves CGRP receptors and altered innervation and vascularization of DsRed2 fluorescent hindpaw tumors

Functional and anatomical relationships among primary afferent fibers, blood vessels, and cancers are poorly understood. However, recent evidence suggests that physical and biochemical interactions between these peripheral components are important to both tumor biology and cancer-associated pain. To determine the role of these peripheral components in a mouse model of cancer pain, we quantified the change in nerve and blood vessel density within a fibrosarcoma tumor mass using stereological analysis of serial confocal optical sections of immunostained hind paw. To this end we introduced the Discoma coral-derived red fluorescent protein (DsRed2) into the NCTC 2472 fibrosarcoma line using the Sleeping Beauty transposon methodology, thus providing a unique opportunity to visualize tumor-nerve-vessel associations in context with behavioral assessment of tumor-associated hyperalgesia. Tumors from hyperalgesic mice are more densely innervated with calcitonin gene related peptide (CGRP)-immunoreactive nerve fibers and less densely vascularized than tumors from non-hyperalgesic mice. As hyperalgesia increased from Day 5 to 12 post-implantation, the density of protein gene product 9.5 (PGP9.5)-immunoreactive nerves and CD31-immunoreactive blood vessels in tumors decreased, whereas CGRP-immunoreactive nerve density remained unchanged. Importantly, intra-tumor injection of a CGRP1 receptor antagonist (CGRP 8-37) partially blocked the tumor-associated mechanical hyperalgesia, indicating that local production of CGRP may contribute to tumor-induced nociception through a receptor-mediated process. The results describe for the first time the interaction among sensory nerves, blood vessels and tumor cells in otherwise healthy tissue, and our assessment supports the hypothesis that direct tumor cell-axon communication may underlie, at least in part, the occurrence of cancer pain.

A distinct microarray gene expression profile in primary rat hepatocytes incubated with ursodeoxycholic acid

BACKGROUND/AIMS

Ursodeoxycholic acid (UDCA) and its taurine-conjugated derivative, TUDCA, modulate cell death and cell cycle regulators, such as E2F-1 and p53. However, precise pathways underlying UDCA's effects are not fully understood. The aim of this study was to identify specific cellular targets of UDCA.

METHODS

The expression profile of primary rat hepatocytes incubated with UDCA was determined using Affymetrix GeneChip Rat 230A arrays. Hybridization data were processed to identify genes with significant expression changes. RT-PCR and immunoblot analyses of a selected target confirmed microarray data.

RESULTS

The results showed that >440 genes were modulated with UDCA by >1.5-fold; approximately 25% were significantly different from controls. Genes affected by UDCA included new regulatory molecules, such as Apaf-1. RT-PCR and immunoblotting confirmed a decrease in Apaf-1. Other altered genes were directly involved in cell cycle (cyclin D1, cadherin 1, HMG-box containing protein 1) and apoptosis (prothymosin-alpha) events. The E2F-1/p53/Apaf-1 pathway appears to be targeted by UDCA. Finally, transcripts for proteins with kinase activity and transcription factors were specifically modulated by TUDCA.

CONCLUSIONS

This study expands our knowledge of the biological effects of UDCA in hepatocytes. Most of the identified genes represent novel potential targets of UDCA, which may ultimately explain its therapeutic properties.

Sleeping Beauty-mediated down-regulation of huntingtin expression by RNA interference

Huntington disease (HD) is a devastating neurologic disorder that is characterized by abnormal expansion of a CAG nt repeat in the first exon of the huntingtin (htt) gene, producing a mutant protein with an elongated polyglutamine stretch. The presence of this mutant protein is correlated with the characteristic loss of striatal neurons and the clinical manifestation of HD. Currently there is no effective treatment for the associated cell death. The aim of this study was to evaluate an innovative strategy combining RNA interference (RNAi) and gene transfer via the nonviral Sleeping Beauty (SB) transposon system to down-regulate Htt expression. siRNA expression vectors were designed to target exons 1, 4, 6, and 62 of the human htt gene. Real-time RT-PCR and Western blot analysis were used to quantify Htt mRNA and protein levels, respectively, in human cell lines. The results indicated that selected siRNA constructs significantly decreased Htt mRNA and protein levels relative to controls. In addition, SB transposition of the siRNA constructs into the genome reduced long-term protein expression of Htt by approximately 90%. The combination of siRNA, the SB transposon, and an accurate transgenic mouse model may permit evaluation of this approach in preventing the pathogenesis associated with expression of mutant Htt.

Double-stranded siRNA targeted to the huntingtin gene does not induce DNA methylation

RNA interference is an evolutionarily conserved mechanism of post-transcriptional gene silencing. Small interfering RNAs (siRNA) of 21-23 nucleotides generated from processing double-stranded RNA (dsRNA) by ribonuclease III, Dicer, are widely used for selective sequence-specific gene silencing in a broad range of organisms. In plants, siRNA is associated with de novo RNA-directed DNA methylation (RdDM) at the homologous target genomic region. To examine RdDM in somatic cells, human glioblastoma cell lines were treated with siRNAs homologous to the human huntingtin gene responsible for Huntington's disease. Methylation of CpG dinucleotides in the plasmid vectors expressing the dsRNAs and homologous genomic region was investigated by bisulfite-mediated genomic sequencing. Target regions of the siRNA in the huntingtin gene showed no significant change in the pattern of DNA methylation, and no CpG methylation was observed on the plasmid vectors. These results indicate that siRNA is not directly linked to DNA methylation at the target huntingtin genomic locus in human cells.

Modulation of nuclear steroid receptors by ursodeoxycholic acid inhibits TGF-beta1-induced E2F-1/p53-mediated apoptosis of rat hepatocytes

We have recently shown that both ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (TUDCA) prevent transforming growth factor beta1 (TGF-beta1)-induced hepatocyte apoptosis by modulating the E2F-1/p53/Bax pathway. In addition, activation of glucocorticoid (GR) and mineralocorticoid receptors (MR) inhibits apoptosis in various systems. UDCA induces a ligand-independent activation of the GR, thus potentially regulating a number of targets. In this study, we investigated the role of GR and MR during TGF-beta1-induced hepatocyte apoptosis, and identified additional antiapoptotic targets for UDCA. Our results showed that in primary hepatocytes, TGF-beta1 induced 40-50% decreases in gr and mr mRNA expression (p < 0.01), together with up to 10-fold reductions in their protein levels (p < 0.01). Notably, pretreatment with UDCA resulted in a significant upregulation of nuclear steroid receptors (p < 0.05), which coincided with 2- and 3-fold increases in the level of GR and MR nuclear translocation, respectively, when compared with that of TGF-beta1 alone (p < 0.05). Similarly, TUDCA induced GR and MR nuclear translocations (p < 0.05) and markedly prevented MR protein changes associated with TGF-beta1 (p < 0.05) without affecting GR protein levels. Moreover, when interference RNA was used to inhibit GR and MR, UDCA no longer protected hepatocytes against TGF-beta1-induced apoptosis. In fact, the protective effect of UDCA in TGF-beta1-associated caspase activation decreased from 65 to <10% when GR or MR function was blocked. Finally, the TGF-beta1-induced E2F-1/Mdm-2/p53 apoptotic pathway, normally inhibited by UDCA, was not regulated by the bile acid after GR or MR silencing. These results demonstrate that UDCA protects against apoptosis through an additional pathway that involves nuclear receptors GR and MR as key factors. Further, the E2F-1/Mdm-2/p53 apoptotic pathway appears to be a prime target for UDCA-induced steroid receptor activation.

A novel system for simultaneous in vivo tracking and biological assessment of leukemia cells and ex vivo generated leukemia-reactive cytotoxic T cells

To determine the mechanisms by which adoptive immunotherapy could reduce lethality to acute myelogenous leukemia (AML), a novel technique was developed to track both leukemic blasts and adoptively transferred cytotoxic T cells (CTLs) independently and simultaneously in mice. To follow the fate of ex vivo generated anti-AML-reactive CTLs, splenocytes obtained from enhanced green fluorescent protein transgenic mice were cocultured with AML lysate-pulsed dendritic cells, which subsequently were expanded by exposure to anti-CD3/CD28 monoclonal antibody-coated magnetic microspheres. To track AML cells, stable transfectants of C1498 expressing DsRed2, a red fluorescent protein, were generated. Three factors related to CTLs correlated with disease-free survival: (a). CTL L-selectin expression. L-Selectin high fractions resulted in 70% disease-free survival, whereas L-selectin low-expressing CTLs resulted in only 30% disease-free survival. (b). Duration of ex vivo expansion (9 versus 16 days). Short-term expanded CTLs could be found at high frequency in lymphoid organs for longer than 4 weeks after transfer, whereas long-term expanded CTLs were cleared from the system after 2 weeks. Duration of expansion correlated inversely with L-selectin expression. (c). CTL dose. A higher dose (40 versus 5 x 10(6)) resulted in superior disease-free survival. This survival advantage was achieved with short-term expanded CTLs only. The site of treatment failure was mainly the central nervous system where no CTLs could be identified at AML sites.

Gene therapy and CVD: how near are we?

Critical for success of any gene therapy approach is the efficient packaging, effective cell specific delivery and nuclear translocation of the nucleic acid with minimal toxicity. Delivery systems utilizing a wide variety of viral vectors have traditionally been used to modify genomic DNA. However, drawbacks to the viral vectors include difficulties in large-scale production, potential contamination by wild-type viral particles and immunogenicity. Thus, efficient non-viral delivery of both plasmids for transgene expression and short oligonucleotides for modulating cellular functions has been developed. Gene therapy is now a consideration in the treatment of certain inherited and acquired genetic disorders associated with cardiovascular disease (CVD). Furthermore, many other cardiovascular conditions are potential targets for gene therapy, and advances in knowledge will increase the ability to link specific genes to a disease, resulting in the identification of further targets. With improvements in delivery and targeting, gene therapy is likely to substantially augment established and emerging therapies in reducing the global burden of cardiovascular disease.

Ursodeoxycholic acid modulates E2F-1 and p53 expression through a caspase-independent mechanism in transforming growth factor beta1-induced apoptosis of rat hepatocytes

Transforming growth factor beta1 (TGF-beta1)-induced hepatocyte apoptosis is associated with activation of E2F transcription factors and p53 stabilization through Mdm-2, thus potentially modulating a number of target genes. In previous studies, we have shown that ursodeoxycholic acid (UDCA) prevents TGF-beta1-induced hepatocyte apoptosis by inhibiting the mitochondrial pathway of cell death. In this study we examined the role of p53 in the induction of apoptosis by TGF-beta1, and identified additional antiapoptosis targets for UDCA. Our data show a significant transcriptional activation of E2F-1 in primary rat hepatocytes incubated with TGF-beta1, as well as a 5-fold increase in p53 and a 2-fold decrease in its inhibitor, Mdm-2 (p < 0.05). In addition, bax mRNA expression was significantly induced at 36 h (p < 0.01), resulting in increased levels of Bax protein. In contrast, Bcl-2 transcript and protein levels were decreased at all time points (p < 0.01). Notably, UDCA inhibited E2F-1 transcriptional activation, p53 stabilization and Bcl-2 family expression (p < 0.05), in part, through a caspase-independent mechanism. Moreover, in the absence of TGF-beta1, UDCA prevented induction of p53 and Bax by overexpression of E2F-1 and p53, respectively (p < 0.05). In addition, UDCA inhibited TGF-beta1-induced degradation of nuclear factor kappaB (NF-kappaB) and its inhibitor IkappaB (p < 0.05). In conclusion, these results demonstrate that UDCA inhibits E2F-1 transcriptional activation of hepatocyte apoptosis, thus modulating p53 stabilization, NF-kappaB degradation, and expression of Bcl-2 family members.

Short, single-stranded oligonucleotides mediate targeted nucleotide conversion using extracts from isolated liver mitochondria

Site-specific single-nucleotide changes in chromosomal DNA of eukaryotic cells have been achieved using chimeric RNA/DNA oligonucleotides (ONs) and short single-stranded (SS) ONs. However, a variety of human diseases originate from single-point mutations in the genome of mitochondrial DNA. We previously demonstrated that extracts from highly purified rat liver mitochondria possess the essential enzymatic activity to mediate targeted single-nucleotide changes using chimeric ONs in vitro. However, different factor(s) and/or mechanism(s) appear to be involved in SS and RNA/DNA ON mediated DNA repair. Because mitochondria are deficient in certain factors involved in nuclear DNA repair pathways, we investigated whether mitochondria possess the enzymatic machinery for SS ON mediated DNA alterations. Using in vitro DNA repair assays based on mutagenized plasmids and a bacterial read-out system, SS ONs were designed to correct the point mutations in the genes encoded by the different plasmids. In this system, protein extracts from purified rat liver mitochondria and nuclei catalyzed similar levels of site-specific nucleotide modifications using SS ONs. Interestingly, extracts isolated from quiescent liver mediated significantly higher conversion rates than those isolated from regenerating liver. The results suggest that mitochondria contain the factors necessary for correction of single-point mutations by SS ONs. In addition, at least some are different than those required for DNA repair by RNA/DNA ONs. Moreover, correction with SS ONs appears to occur one strand at a time suggesting that repair of the DNA substrate involves strand transfer. The ability of unmodified SS ONs to mediate targeted alteration of the mitochondrial genome may provide a new tactic for treatment of certain mitochondrial-based diseases.

Gene therapy as an alternative to liver transplantation

Liver transplantation has become a well-recognized therapy for hepatic failure resulting from acute or chronic liver disease. It also plays a role in the treatment of certain inborn errors of metabolism that do not directly injure the liver. In fact, the liver maintains a central role in many inherited and acquired genetic disorders. There has been a considerable effort to develop new and more effective gene therapy approaches, in part, to overcome the need for transplantation as well as the shortage of donor livers. Traditional gene therapy involves the delivery of a piece of DNA to replace the faulty gene. More recently, there has been a growing interest in the use of gene repair to correct certain genetic defects. In fact, targeted gene repair has many advantages over conventional replacement strategies. In this review, we will describe a variety of viral and nonviral strategies that are now available to the liver. The ever-growing list includes viral vectors, antisense and ribozyme technology, and the Sleeping Beauty transposon system. In addition, targeted gene repair with RNA/DNA oligonucleotides, small-fragment homologous replacement, and triplex-forming and single-stranded oligonucleotides is a long-awaited and potentially exciting approach. Although each method uses different mechanisms for gene repair and therapy, they all share a basic requirement for the efficient delivery of DNA.

The application of DNA repair vectors to gene therapy

The nature of DNA, the sequence of the human genome and our increased understanding of the genetic basis of many inherited and acquired disorders have made the possibility of curing diseases a reality. The modulation of a host's genome is now the ultimate goal in the treatment of genetic diseases. Historically, gene therapy recognized two very different approaches: gene replacement or augmentation and gene repair. Gene repair precisely targets and corrects the chromosomal mutation responsible for a genetic and/or acquired disorder. Many recent advances have been made in this area of research.

Unbound E2F modulates TGF-β1-induced apoptosis in HuH-7 cells

E2F is an important target of the retinoblastoma protein (pRb) and plays a critical role in G1/S progression through the cell cycle. TGF-β1 arrests HuH-7 cells in G1 by suppressing phosphorylation of pRb and induces apoptosis by inhibiting its expression. In this study, we examined the downstream effects of TGF-β1-induced apoptosis and the potential roles for pRb and E2F. The results indicated that greater than 90% of the TGF-β1-induced preapoptotic cells were arrested in G1 phase of the cell cycle. This was associated with a significant increase in both E2F-DNA-binding activity and transcription of E2F-responsive reporter constructs. In contrast, no significant changes were observed in E2F mRNA and protein levels, and the overexpression of pRb partially inhibited E2F activation. Gel-shift assays identified more than four E2F complexes from preapoptotic and synchronized G1 HuH-7 cells,each exhibiting different patterns of E2F-associated proteins. The increased E2F activity did not affect the association patterns with pRb, p107 and p130,but altered the formation of an E2F—DP-1 complex. In contrast,E2F—DP-2 exhibited little change in the preapoptotic cells. Moreover,TGF-β1 induced apoptosis at G1 and inhibited entry into S phase irrespective of the increased E2F activity. The release of preapoptotic cells from TGF-β1 resulted in rapid S phase entry and subsequent apoptosis in 33% of cells over a 72 hour period. In conclusion, the results demonstrate that TGF-β1-induced apoptosis in HuH-7 cells is associated with a marked increase in activity of transcription factor E2F that is partially inhibited by overexpression of pRb. Preapoptotic changes are, in part, reversible upon removal of TGF-β1 and the majority of cells re-enter the normal cell cycle. Finally, TGF-β1-induced apoptosis with the associated increase in E2F activity can occur in both the G1and S phases of the cell cycle.

Gene repair and transposon-mediated gene therapy

The main strategy of gene therapy has traditionally been focused on gene augmentation. This approach typically involves the introduction of an expression system designed to express a specific protein in the transfected cell. Both the basic and clinical sciences have generated enough information to suggest that gene therapy would eventually alter the fundamental practice of modern medicine. However, despite progress in the field, widespread clinical applications and success have not been achieved. The myriad deficiencies associated with gene augmentation have resulted in the development of alternative approaches to treat inherited and acquired genetic disorders. One, derived primarily from the pioneering work of homologous recombination, is gene repair. Simply stated, the process involves targeting the mutation in situ for gene correction and a return to normal gene function. Site-specific genetic repair has many advantages over augmentation although it too is associated with significant limitations. This review outlines the advantages and disadvantages of gene correction. In particular, we discuss technologies based on chimeric RNA/DNA oligonucleotides, single-stranded and triplex-forming oligonucleotides, and small fragment homologous replacement. While each of these approaches is different, they all share a number of common characteristics, including the need for efficient delivery of nucleic acids to the nucleus. In addition, we review the potential application of a novel and exciting nonviral gene augmentation strategy--the Sleeping Beauty transposon system.