Transcriptional regulation of inducible nitric oxide synthase gene therapy: targeting early stage and advanced prostate cancer

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

A health disparities study of MicroRNA-146a expression in prostate cancer samples derived from African American and European American patients

Considering the prevalence of prostate cancer all over the world, it is desired to have tools, technologies, and biomarkers which help in early detection of the disease and discriminate different races and ethnic groups. Genetic information from the single gene analysis and genome-wide association studies have identified few biomarkers, however, the drivers of prostate cancer remain unknown in the majority of prostate cancer patients. In those cases where genetic association has been identified, the genes confer only a modest risk of this cancer, hence, making them less relevant for risk counseling and disease management. There is a need for additional biomarkers for diagnosis and prognosis of prostate cancer. MicroRNAs are a class of non-protein coding RNA molecules that are frequently dysregulated in different cancers including prostate cancer and show promise as diagnostic biomarkers and targets for therapy. Here we describe the role of micro RNA 146a (miR-146a) which may serve as a diagnostic and prognostic marker for prostate cancer, as indicated from the data presented in this report. Also, a pilot study indicated differential expression of miR-146a in prostate cancer cell lines and tissues from different racial groups. Reduced expression of miR-146a was observed in African American tumor tissues compared to those from European Whites This report provides a novel insight into understanding the prostate carcinogenesis.

Heterogeneous nuclear ribonucleoprotein (hnRNPL) in cancer

Heterogeneous nuclear ribonucleoprotein L (hnRNPL) is a type of RNA binding protein that is mainly located in the nucleus. hnRNPL protein, encoded by the gene located at 19q13.2, is an important member of the hnRNP family. In recent years, studies have shown that hnRNPL is highly expressed in a variety of tumors and plays a vital role in tumor progression. hnRNPL promotes various biological processes of tumor cells, including proliferation, migration and invasion. In this review, we discuss the clinical significance of hnRNPL by reviewing the mechanism of hnRNPL in the tumorigenesis of various cancers.

Gene therapy with RALA/iNOS composite nanoparticles significantly enhances survival in a model of metastatic prostate cancer

BACKGROUND

Recent approvals of gene therapies by the FDA and the EMA for treatment of inherited disorders have further opened the door for assessment of nucleic acid pharmaceuticals for clinical usage. Arising from the presence of damaged or inappropriate DNA, cancer is a condition particularly suitable for genetic intervention. The RALA peptide has been shown to be a potent non-viral delivery platform for nucleic acids. This study examines the use of RALA to deliver a plasmid encoding inducible nitric oxide synthase (iNOS) as an anti-cancer treatment.

METHODS

The physiochemical properties of the RALA/DNA nanoparticles were characterized via dynamic light scattering and transmission electron microscopy. The nanoparticles were labelled with fluorophores and tracked over time using confocal microscopy with orthogonal sections to determine cellular location. In vitro studies were employed to determine functionality of the nanoparticles both for pEGFP-N1 and CMV-iNOS. Nanoparticles were injected intravenously into C57/BL6 mice with blood and serum samples analysed for immune response. PC3-luc2M cells were injected into the left ventricle of SCID mice followed by treatment with RALA/CMV-iNOS nanoparticles to evaluate the tumour response in a metastatic model of prostate cancer.

RESULTS

Functional cationic nanoparticles were produced with gene expression in PC-3 prostate cancer cells. Furthermore, repeated administrations of RALA/DNA nanoparticles into immunocompetent mice did not produce any immunological response: neutralization of the vector or release of inflammatory mediators. RALA/CMV-iNOS reduced the clonogenicity of PC-3 cells in vitro, and in an in vivo model of prostate cancer metastasis, systemically delivered RALA/CMV-iNOS significantly improved the survival of mice.

CONCLUSION

These studies further validate RALA as a genetic cargo delivery vehicle and iNOS as a potent therapy for the treatment of cancer.

Seek and destroy: targeted adeno-associated viruses for gene delivery to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer with high incidence globally. Increasing mortality and morbidity rates combined with limited treatment options available for advanced HCC press for novel and effective treatment modalities. Gene therapy represents one of the most promising therapeutic options. With the recent approval of herpes simplex virus for advanced melanoma, the field of gene therapy has received a major boost. Adeno-associated virus (AAV) is among the most widely used and effective viral vectors today with safety and efficacy demonstrated in a number of human clinical trials. This review identifies the obstacles for effective AAV based gene delivery to HCC which primarily include host immune responses and off-target effects. These drawbacks could be more pronounced for HCC because of the underlying liver dysfunction in most of the patients. We discuss approaches that could be adopted to tackle these shortcomings and manufacture HCC-targeted vectors. The combination of transductional targeting by modifying the vector capsid and transcriptional targeting using HCC-specific promoters has the potential to produce vectors which can specifically seek HCC and deliver therapeutic gene without significant side effects. Finally, the identification of novel HCC-specific ligands and promoters should facilitate and expedite this process.

Systemic RALA/iNOS Nanoparticles: A Potent Gene Therapy for Metastatic Breast Cancer Coupled as a Biomarker of Treatment

This study aimed to determine the therapeutic benefit of a nanoparticular formulation for the delivery of inducible nitric oxide synthase (iNOS) gene therapy in a model of breast cancer metastasis. Nanoparticles comprising a cationic peptide vector, RALA, and plasmid DNA were formulated and characterized using a range of physiochemical analyses. Nanoparticles complexed using iNOS plasmids and RALA approximated 60 nm in diameter with a charge of 25 mV. A vector neutralization assay, performed to determine the immunogenicity of nanoparticles in immunocompetent C57BL/6 mice, revealed that no vector neutralization was evident. Nanoparticles harboring iNOS plasmids (constitutively active cytomegalovirus [CMV]-driven or transcriptionally regulated human osteocalcin [hOC]-driven) evoked iNOS protein expression and nitrite accumulation and impaired clonogenicity in the highly aggressive MDA-MB-231 human breast cancer model. Micrometastases of MDA-MB-231-luc-D3H1 cells were established in female BALB/c SCID mice by intracardiac delivery. Nanoparticulate RALA/CMV-iNOS or RALA/hOC-iNOS increased median survival in mice bearing micrometastases by 27% compared with controls and also provoked elevated blood nitrite levels. Additionally, iNOS gene therapy sensitized MDA-MB-231-luc-D3H1 tumors to docetaxel treatment. Studies demonstrated that systemically delivered RALA-iNOS nanoparticles have therapeutic potential for the treatment of metastatic breast cancer. Furthermore, detection of nitrite levels in the blood serves as a reliable biomarker of treatment.

Non-viral nucleic acid delivery methods

INTRODUCTION

Delivery of nucleic acid-based molecules in human cells is a highly studied approach for the treatment of several disorders including monogenic diseases and cancers. Non-viral vectors for DNA and RNA transfer, although in general less efficient than virus-based systems, are particularly well adapted mostly due to the absence of biosafety concerns. Non-viral methods could be classified in two main groups: physical and vector-assisted delivery systems. Both groups comprise several different methods, none of them universally applicable. The choice of the optimal method depends on the predefined objectives and the features of targeted micro-environment. Areas covered: In this review, the authors discuss non-viral techniques and present recent therapeutic achievements in ex vivo and in vivo nucleic acid delivery by most commonly used techniques while emphasizing the role of 'biological particles', namely peptide transduction domains, virus like particles, gesicles and exosomes. Expert opinion: The number of available non-viral transfection techniques used for human therapy increased rapidly, followed by still moderate success in efficacy. The prospects are to be found in design of multifunctional hybrid systems that reflect the viral efficiency. In this respect, biological particles are very promising.

Investigating the role of tumour cell derived iNOS on tumour growth and vasculature in vivo using a tetracycline regulated expression system

Nitric oxide (NO) is a free radical signalling molecule involved in various physiological and pathological processes, including cancer. Both tumouricidal and tumour promoting effects have been attributed to NO, making its role in cancer biology controversial and unclear. To investigate the specific role of tumour-derived NO in vascular development, C6 glioma cells were genetically modified to include a doxycycline regulated gene expression system that controls the expression of an antisense RNA to inducible nitric oxide synthase (iNOS) to manipulate endogenous iNOS expression. Xenografts of these cells were propagated in the presence or absence of doxycycline. Susceptibility magnetic resonance imaging (MRI), initially with a carbogen (95% O2/5% CO2) breathing challenge and subsequently an intravascular blood pool contrast agent, was used to assess haemodynamic vasculature (ΔR2*) and fractional blood volume (fBV), and correlated with histopathological assessment of tumour vascular density, maturation and function. Inhibition of NO production in C6 gliomas led to significant growth delay and inhibition of vessel maturation. Parametric fBV maps were used to identify vascularised regions from which the carbogen-induced ΔR2* was measured and found to be positively correlated with vessel maturation, quantified ex vivo using fluorescence microscopy for endothelial and perivascular cell staining. These data suggest that tumour-derived iNOS is an important mediator of tumour growth and vessel maturation, hence a promising target for anti-vascular cancer therapies. The combination of ΔR2* response to carbogen and fBV MRI can provide a marker of tumour vessel maturation that could be applied to non-invasively monitor treatment response to iNOS inhibitors.

Vectors and strategies for nonviral cancer gene therapy

INTRODUCTION

This review presents recent developments in the use of nonviral vectors and transfer technologies in cancer gene therapy. Tremendous progress has been made in developing cancer gene therapy in ways that could be applicable to treatments. Numerous efforts are focused on methods of attacking known and novel targets more efficiently and specifically. In parallel to progress in nonviral vector design and delivery technologies, important achievements have been accomplished for suicide, gene replacement, gene suppression and immunostimulatory therapies. New nonviral cancer gene therapies have been developed based on emerging RNAi (si/shRNA-, miRNA) or ODN.

AREAS COVERED

This review provides an overview of recent gene therapeutic strategies in which nonviral vectors have been used experimentally and in clinical trials. Furthermore, we present current developments in nonviral vector systems in association with important chemical and physical gene delivery technologies and their potential for the future.

EXPERT OPINION

Nonviral gene therapy has maintained its position as an approach for treating cancer. This is reflected by the fact that more than 17% of all gene therapy trials employ nonviral approaches. Thus, nonviral vectors have emerged as a clinical alternative to viral vectors for the appropriate expression and delivery of therapeutic genes.

Current status of gene therapy for breast cancer: progress and challenges

Breast cancer is characterized by a series of genetic mutations and is therefore ideally placed for gene therapy intervention. The aim of gene therapy is to deliver a nucleic acid-based drug to either correct or destroy the cells harboring the genetic aberration. More recently, cancer gene therapy has evolved to also encompass delivery of RNA interference technologies, as well as cancer DNA vaccines. However, the bottleneck in creating such nucleic acid pharmaceuticals lies in the delivery. Deliverability of DNA is limited as it is prone to circulating nucleases; therefore, numerous strategies have been employed to aid with biological transport. This review will discuss some of the viral and nonviral approaches to breast cancer gene therapy, and present the findings of clinical trials of these therapies in breast cancer patients. Also detailed are some of the most recent developments in nonviral approaches to targeting in breast cancer gene therapy, including transcriptional control, and the development of recombinant, multifunctional bio-inspired systems. Lastly, DNA vaccines for breast cancer are documented, with comment on requirements for successful pharmaceutical product development.

Association between endothelial nitric oxide synthase 894G>T polymorphism and prostate cancer risk: a meta-analysis of literature studies

To date, several studies have been conducted to assess the association between endothelial nitric oxide synthase (eNOS) gene 894G > T polymorphism and prostate cancer (PCa) risk, but the results are conflicting. To derive a more precise estimation of the relationship between 894G > T polymorphism and PCa risk, the present meta-analysis was performed. A total of eight case-control studies were included in this meta-analysis. The pooled odds ratio (OR) with 95 % confidence interval (CI) was calculated to evaluate the associations. Our results suggested that 894G > T polymorphism is associated with PCa risk under codominant (GT vs. GG) (OR = 1.11, 95 % CI = 1.01-1.22, P = 0.04) and overdominant (GT vs. GG + TT) (OR = 1.12, 95 % CI = 1.02-1.23, P = 0.02) models in the overall population, while there are no associations observed under dominant (GT + TT vs. GG), recessive (TT vs. GG + GT), and allelic (T vs. G) models. Moreover, when the eligible studies were stratified according to sources of control, significant association between 894G > T polymorphism and susceptibility of PCa was also identified under codominant (OR = 1.12, 95 % CI = 1.01-1.24, P = 0.03) and overdominant (OR = 1.13, 95 % CI = 1.02-1.25, P = 0.02) models when using healthy individuals as control. However, there are no significant associations found under any genetic models when using BPH patients as control group. In conclusion, the present meta-analysis suggested that the eNOS gene 894G > T polymorphism might be a risk factor in the onset of PCa.

Delivery of nitric oxide to the interior of mammalian cell by carbon nanotube: MD simulation

Computer simulations have been performed to study the nanoindentation of phospholipid bilayer by the single-walled armchair carbon nanotube, filled with the nitric oxide molecules. The process has been simulated by means of molecular dynamics (MD) technique at physiological temperature T = 310 K with a constant pulling velocity of the nanotube. The force acting on the nanotube during membrane penetration has been calculated. We show that the indentation by carbon nanotube does not permanently destroy the membrane structure (self-sealing of the membrane occurs). The mobility of nitric oxide molecules during the membrane nanoindentation is discussed.

Prolactin/Stat5 and androgen R1881 coactivate carboxypeptidase-D gene in breast cancer cells

Plasma membrane-bound carboxypeptidase-D (CPD) cleaves C-terminal arginine from extracellular substrates. In the cell, arginine is converted to nitric oxide (NO). We have reported that up-regulation of CPD mRNA/protein levels by 17β-estradiol and prolactin (PRL) in breast cancer cells, and by testosterone in prostate cancer cells, increased NO production and cell survival. The CPD promoter contains a consensus γ-interferon-activated sequence (GAS) and 3 putative androgen response elements (ARE.1, ARE.2, ARE.3) that could potentially bind PRL-activated transcription factor Stat5 (signal transducer and activator of transcription 5) and the liganded androgen receptor (AR), respectively. This study showed that synthetic androgen R1881 and PRL elevated CPD mRNA/protein levels in human MCF-7 and T47D breast cancer cells in a time-/dose-dependent manner. PRL/R1881-elevated CPD expression was blocked by actinomycin-D, and a CPD promoter construct containing these GAS and AREs was stimulated by PRL or R1881, indicating transcriptional regulation by both hormones. Luciferase reporter assays showed that GAS and the adjacent ARE.1 only were active. Mutation of GAS in the ΔGAS-CPD construct (ARE.1 intact) abolished CPD promoter activity in response to PRL and, surprisingly, to R1881 as well. ΔGAS-CPD promoter activity was restored by PRL+R1881 in combination, and enhanced by ectopic Stat5, but abolished by Stat5 gene knockdown. Chromatin immunoprecipitation analysis confirmed binding of activated Stat5 and liganded AR to GAS and ARE.1, respectively. Activated Stat5 also induced binding of unliganded AR to ARE.1, and liganded AR induced binding of unactivated Stat5 to GAS. In summary, PRL and R1881, acting through Stat5 and AR, act cooperatively to stimulate CPD gene transcription in breast cancer cells.

Nitrosylhemoglobin in photodynamically stressed human tumors growing in nude mice

The role of nitric oxide in human tumor biology and therapy has been the subject of extensive studies. However, there is only limited knowledge about the mechanisms of NO production and its metabolism, and about the role NO can play in modern therapeutic procedures, such as photodynamic therapy. Here, for the first time, we report the presence of nitrosylhemoglobin, a stable complex of NO, in human lung adenocarcinoma A549 tumors growing in situ in nude mice. Using electron paramagnetic resonance spectroscopy we show that the level of nitrosylhemoglobin increases in the course of photodynamic therapy and that the phenomenon is local. Even the destruction of strongly vascularized normal liver tissue did not induce the paramagnetic signal, despite bringing about tissue necrosis. We conclude that photodynamic stress substantiates NO production and blood extravasation in situ, both processes on-going even in non-treated tumors, although at a lower intensity.

Positive correlation between PEDF expression levels and macrophage density in the human prostate

BACKGROUND

In this study, we investigated the capacity of pigment epithelium-derived factor (PEDF) to modulate the recruitment and the differentiation of monocytes/macrophages both in vitro and in human prostate.

METHODS

Using Boyden chambers, we assessed PEDF effect on the migration of monocytes and chemically activated RAW 264.7 macrophages. Normal, prostatitis, and prostate cancer specimens were retrospectively selected and examined by immunohistochemistry for PEDF expression and infiltration of immune CD68 + macrophagic cells. PEDF expression and macrophage density were then correlated with each other and clinicopathological parameters. M1 and M2 differentiation markers were quantified by qRT-PCR, Western blotting, and ELISA.

RESULTS

In chemotaxis, PEDF induced the migration of monocytes/macrophages. In immunohistochemistry, macrophages were markedly increased in prostatitis and malignant compared to normal tissues. PEDF was expressed at variable levels in the stroma and epithelium. PEDF mRNA was down-regulated in both prostate cancer and prostatitis compared to normal tissues. In correlation studies, macrophage density and PEDF expression were respectively positively and negatively associated with prostate size. Most importantly, PEDF expression positively correlated with macrophage density. Finally, PEDF stimulated the expression of iNOS, IL12, and TNFα; and inhibited IL10 and arginase 1 in mouse and human macrophages confirming a M1-type differentiation.

CONCLUSIONS

Our data demonstrate that PEDF acts directly on monocytes/macrophages by inducing their migration and differentiation into M1-type cells. These findings suggest a possible role of macrophages in PEDF anti-tumor properties and may support further development of PEDF-based anti-cancer therapy.

The yin and yang of nitric oxide in cancer progression

Nitric oxide (NO) is a short-lived, pleiotropic molecule that affects numerous critical functions in the body. Presently, there are markedly conflicting findings in the literature regarding NO and its role in carcinogenesis and tumor progression. NO has been shown to have dichotomous effects on cellular proliferation, apoptosis, migration, invasion, angiogenesis and many other important processes in cancer biology. It has been shown to be both pro- and antitumorigenic, depending on the concentration and the tumor microenvironment in question. NO is generated by three isoforms of NO synthase (NOS) that are widely expressed and sometimes upregulated in human tumors. Due to its vast array of physiological functions, it presents a huge challenge to researchers to discover its true potential in cancer biology and consequently, its use in anticancer therapies. In this study, we review the current knowledge in this area, with an emphasis placed on NO modulation as an anticancer therapy, focusing on NO-donating drugs and NOS inhibitors.

Plumbagin, a medicinal plant (Plumbago zeylanica)-derived 1,4-naphthoquinone, inhibits growth and metastasis of human prostate cancer PC-3M-luciferase cells in an orthotopic xenograft mouse model

We present here first time that Plumbagin (PL), a medicinal plant-derived 1,4-naphthoquinone, inhibits the growth and metastasis of human prostate cancer (PCa) cells in an orthotopic xenograft mouse model. In this study, human PCa PC-3M-luciferase cells (2 × 10(6)) were injected into the prostate of athymic nude mice. Three days post cell implantation, mice were treated with PL (2 mg/kg body wt. i.p. five days in a week) for 8 weeks. Growth and metastasis of PC-3M-luciferase cells was examined weekly by bioluminescence imaging of live mice. PL-treatment significantly (p = 0.0008) inhibited the growth of orthotopic xenograft tumors. Results demonstrated a significant inhibition of metastasis into liver (p = 0.037), but inhibition of metastasis into the lungs (p = 0.60) and lymph nodes (p = 0.27) was not observed to be significant. These results were further confirmed by histopathology of these organs. Results of histopathology demonstrated a significant inhibition of metastasis into lymph nodes (p = 0.034) and lungs (p = 0.028), and a trend to significance in liver (p = 0.075). None of the mice in the PL-treatment group showed PCa metastasis into the liver, but these mice had small metastasis foci into the lymph nodes and lungs. However, control mice had large metastatic foci into the lymph nodes, lungs, and liver. PL-caused inhibition of the growth and metastasis of PC-3M cells accompanies inhibition of the expression of: 1) PKCε, pStat3Tyr705, and pStat3Ser727, 2) Stat3 downstream target genes (survivin and Bcl(xL)), 3) proliferative markers Ki-67 and PCNA, 4) metastatic marker MMP9, MMP2, and uPA, and 5) angiogenesis markers CD31 and VEGF. Taken together, these results suggest that PL inhibits tumor growth and metastasis of human PCa PC3-M-luciferase cells, which could be used as a therapeutic agent for the prevention and treatment of human PCa.

Implications of pleiotrophin in human PC3 prostate cancer cell growth in vivo

Pleiotrophin (PTN) is a heparin-binding growth factor with diverse functions related to tumor growth, angiogenesis, and metastasis. Pleiotrophin seems to have a significant role in prostate cancer cell growth and to mediate the stimulatory actions of other factors that affect prostate cancer cell functions. However, all studies carried out up to date are in vitro, using different types of human prostate cancer cell lines. The aim of the present work was to study the role of endogenous PTN in human prostate cancer growth in vivo. For this purpose, human prostate cancer PC3 cells were stably transfected with a plasmid vector, bearing the antisense PTN sequence, in order to inhibit PTN expression (AS-PC3). Migration, apoptosis, and adhesion on osteoblastic cells were measured in vitro. In vivo, PC3 cells were s.c. injected into male NOD/SCID mice, and tumor growth, survival rates, angiogenesis, apoptosis, and the number of metastasis were estimated. Pleiotrophin depletion resulted in a decreased migration capability of AS-PC3 cells compared with the corresponding mock-transfected or the non-transfected PC3 cells, as well as increased apoptosis and decreased adhesiveness to osteoblastic cells in vitro. In prostate cancer NOD/SCID mouse xenografts, PTN depletion significantly suppressed tumor growth and angiogenesis and induced apoptosis of cancer cells. In addition, PTN depletion decreased the number of metastases, providing a survival benefit for the animals bearing AS-PC3 xenografts. Our data suggest that PTN is implicated in human prostate cancer growth in vivo and could be considered a potential target for the development of new therapeutic approaches for prostate cancer.

Methods of nitric oxide detection in plants: a commentary

Over the last decade nitric oxide (NO) has been shown to influence a range of processes in plants. However, when, where and even if NO production occurs is controversial in several physiological scenarios in plants. This arises from a series of causes: (a) doubts have arisen over the specificity of widely used 4,5-diaminofluorescein diacetate (DAF-2DA)/4-amino-5-methylamino-2,7-difluorofluorescein (DAF-FM) dyes for NO, (b) no plant nitric oxide synthase (NOS) has been cloned, so that the validity of using mammalian NOS inhibitors to demonstrate that NO is being measured is debatable, (c) the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide (cPTIO) needs to be used with caution, and (d) some discrepancies between assays for in planta measurements and another based on sampling NO from the gas phase have been reported. This review will outline some commonly used methods to determine NO, attempt to reconcile differing results obtained by different laboratories and suggest appropriate approaches to unequivocally demonstrate the production of NO.