Stable transgene expression in tumors and metastases after transduction with lentiviral vectors based on human immunodeficiency virus type 1

Elevated NIBP/TRAPPC9 mediates tumorigenesis of cancer cells through NFκB signaling

Regulatory mechanisms underlying constitutive and inducible NFκB activation in cancer remain largely unknown. Here we investigated whether a novel NIK- and IKK2-binding protein (NIBP) is required for maintaining malignancy of cancer cells in an NFκB-dependent manner. Real-time polymerase chain reaction analysis of a human cancer survey tissue-scan cDNA array, immunostaining of a human frozen tumor tissue array and immunoblotting of a high-density reverse-phase cancer protein lysate array showed that NIBP is extensively expressed in most tumor tissues, particularly in breast and colon cancer. Lentivirus-mediated NIBP shRNA knockdown significantly inhibited the growth/proliferation, invasion/migration, colony formation and xenograft tumorigenesis of breast (MDA-MB-231) or colon (HCT116) cancer cells. NIBP overexpression in HCT116 cells promoted cell proliferation, migration and colony formation. Mechanistically, NIBP knockdown in cancer cells inhibited cytokine-induced activation of NFκB luciferase reporter, thus sensitizing the cells to TNFα-induced apoptosis. Endogenous NIBP bound specifically to the phosphorylated IKK2 in a TNFα-dependent manner. NIBP knockdown transiently attenuated TNFα-stimulated phosphorylation of IKK2/p65 and degradation of IκBα. In contrast, NIBP overexpression enhanced TNFα-induced NFκB activation, thus inhibiting constitutive and TNFα-induced apoptosis. Collectively, our data identified important roles of NIBP in promoting tumorigenesis via NFκΒ signaling, spotlighting NIBP as a promising target in cancer therapeutic intervention.

Src-mediated morphology transition of lung cancer cells in three-dimensional organotypic culture

A fribotic tumor microenvironment promotes progression of cancer. In this study, we utilize a reconstituted basement membrane mimics Matrigel based three-dimensional organotypic culture (rBM 3-D) to investigate the mechanisms that mediate the tumor promoting effects of the fibrogenic mediators TGF-β1 and type I collagen (Col-1) on lung adenocarcinoma cells. Similar to normal alveolar epithelial cells, the well-differentiated lung adenocarcinoma cells in rBM 3-D culture undergo acinar morphogeneis that features polarized epithelial cell spheres with a single central lumen. Either TGF-β1 or Col-1 modestly distorts acinar morphogenesis. On the other hand, TGF-β1 and Col-1 synergistically induce a transition from acinar morphology into stellate morphology that is characteristic of invasive and metastatic cancer cells. Inhibition of the Src kinase activity abrogates induction of stellate morphology, activation of Akt and mTOR, and the expression of tumor promoting genes by TGF-β1 and Col-1. To a similar extent, pharmacological inhibition of mTOR abrogates the cellular responses to TGF-β1 and Col-1. In summary, we demonstrate that TGF-β1 and Col-1 promote stellate morphogenesis of lung cancer cells. Our findings further suggest that the Src-Akt-mTOR axis mediates stellate morphogenesis. These findings also indicate that rBM 3-D culture can serve as an ideal platform for swift and cost-effective screening of therapeutic candidates at the interface of the tumor and its microenvironment.

Comparative profiling of miRNA expression of lung adenocarcinoma cells in two-dimensional and three-dimensional cultures

Three-dimensional organotypic culture using reconstituted basement membrane matrix (rBM 3-D) is an invaluable tool to characterize morphogenesis of epithelial cells and to elucidate the tumor-modulating actions of extracellular matrix. microRNAs (miRNA) are a novel class of tumor modulating genes. A substantial amount of investigation of miRNAs in cancer is carried out using monolayer 2-D culture on plastic substratum, which lacks a consideration of the matrix-mediated regulation of miRNAs. In the current study we compared the expression of miRNAs in rBM 3-D and 2-D cultures of two lung adenocarcinoma cell lines. Our findings revealed a profound difference in miRNA profiles between 2-D and rBM 3-D cultures of lung adenocarcinoma cells. The rBM 3-D culture-specific miRNA profile was highlighted with higher expression of the tumor suppressive miRNAs (i.e., miR-200 family) and lower expression of the oncogenic miRNAs (i.e., miR-17-92 cluster and miR-21) than that of 2-D culture. Moreover, the expression pattern of miR-17, miR-21, and miR-200a in rBM 3-D culture correlated with the expression of their targets and acinar morphogenesis, a differentiation behavior of lung epithelial cells in rBM 3-D culture. Over-expression of miR-21 suppressed its target PTEN and disrupted acinar morphogenesis. In summary, we provide the first miRNA profile of lung adenocarcinoma cells in rBM 3-D culture with respect to acinar morphogenesis. These results indicate that rBM 3-D culture is essential to a comprehensive understanding of the miRNA biology in lung epithelial cells pertinent to lung adenocarcinoma.

Increased expression of P-glycoprotein is associated with doxorubicin chemoresistance in the metastatic 4T1 breast cancer model

Development of drug resistance is one of the major causes of breast cancer treatment failure. The goal of this study was to understand the chemoresistance mechanism using the highly metastatic 4T1 breast cancer model, which emulates stage IV breast cancer in humans. The metastatic 4T1 breast cancer cell line treated with either doxorubicin or 5-FU showed a concentration-dependent reduced cell proliferation, with induced G2-phase growth arrest (doxorubicin) or G1-phase growth arrest (5-FU). Doxorubicin treatment partially suppressed the multiorgan metastasis of 4T1 breast cancer cells in the lung, heart, liver, and bone, compared with either 5-FU or cyclophosphamide. We isolated and characterized 4T1 breast cancer cells from doxorubicin-resistant metastatic tumors (cell line 4T1-R). Multiorgan metastasis of drug-resistant 4T1 breast tumors was totally resistant to doxorubicin treatment. Our results indicate that doxorubicin is localized exclusively in the cytoplasm of resistant 4T1 breast cancer cells and that it cannot reach the nucleus because of increased nuclear expression of P-glycoprotein. Pretreatment of doxorubicin-resistant 4T1-R breast cancer cells with verapamil, a general inhibitor of P-glycoprotein, increased nuclear translocation of doxorubicin and cellular cytotoxicity. Thus, impaired nuclear translocation of doxorubicin due to increased expression of P-glycoprotein is associated with doxorubicin resistance of highly metastatic 4T1 breast cancer.

Generation of domestic transgenic cloned kittens using lentivirus vectors

The efficient use of somatic cell nuclear transfer (SCNT), in conjunction with genetic modification of donor cells provides a general means to add or inactivate genes in mammals. This strategy has substantially improved the efficacy of producing genetically identical animals carrying mutant genes corresponding to specific human disorders. Lentiviral (LV) vectors have been shown to be well suited for introducing transgenes into cells to be used as donor nuclei for SCNT. In the present study, we established an LV vector-based transgene delivery approach for producing live transgenic domestic cats by SCNT. We have demonstrated that cat fetal fibroblasts can be transduced with EGFP-encoding LV vectors bearing various promoters including the human cytomegalovirus immediate early (hCMV-IE) promoter, the human translation elongation factor 1alpha (hEF-1alpha) promoter and the human ubiquitin C (hUbC) promoter. Among the promoters tested, embryos reconstructed with donor cells transduced with a LV-vector bearing the hUbC promoter displayed sustained transgene expression at the blastocyst stage while embryos reconstructed with LV vector-transduced cells containing hCMV-IE-EGFP or hEF-1alpha-EGFP cassettes did not. After transfer of 291 transgenic cloned embryos into the oviducts of eight recipient domestic cats (mean =36.5 +/- 10.1), three (37.5%) were diagnosed to be pregnant, and a total of six embryos (2.1%) implanted. One live male offspring was delivered by Cesarean section on day 64 of gestation, and two kittens were born dead after premature delivery on day 55. In summary, we report the birth of transgenic cloned kittens produced by LV vector-mediated transduction of donor cells and confirm that cloned kittens express the EGFP reporter transgene in all body tissues.

Lentiviral gene transfer to reduce atherosclerosis progression by long-term CC-chemokine inhibition

CC-chemokines are important mediators in the pathogenesis of atherosclerosis. Atherosclerosis progression is reduced by high-level, short-term inhibition of CC-chemokine activity, for example by adenoviral gene transfer. However, atherosclerosis is a chronic condition where short-term effects, while demonstrating proof-of-principle, are unlikely to provide maximum therapeutic benefit. Accordingly, we generated a recombinant lentivirus, lenti35K, encoding the broad-spectrum CC chemokine inhibitor, 35K, derived from the vaccinia virus. To investigate the effects of prolonged broad-spectrum chemokine inhibition on atherosclerosis, lenti35K, or lentiGFP or PBS were delivered to 6-week-old ApoE knockout (ApoE-KO) mice by hydrodynamic injection. Sustained lentiviral transduction and transgene expression were demonstrated by 35K mRNA and viral DNA in liver tissue, and recombinant 35K protein circulating in the plasma, 3 months after gene transfer. Plasma from lenti35K animals had reduced chemokine activity compared with plasma from lentiGFP or PBS-treated animals. Histologic analysis of aortic sinus sections revealed that atherosclerotic plaque area in lenti35K mice was significantly reduced compared with both lentiGFP and PBS controls. Furthermore, plaque macrophage content was substantially reduced in lenti35K mice. Lentiviral 35K gene transfer is a promising experimental strategy to reduce atherosclerosis progression, and demonstrates the potential of long-term CC-chemokine inhibition as a potential therapeutic target in atherosclerosis.

A rapid and efficient branched DNA hybridization assay to titer lentiviral vectors

A robust assay to titer lentiviral vectors is imperative to qualifying their use in drug discovery, target validation and clinical applications. In this study, a novel branched DNA based hybridization assay was developed to titer lentiviral vectors by quantifying viral RNA genome copy numbers from viral lysates without having to purify viral RNA, and this approach was compared with other non-functional (p24 protein ELISA and viral RT-qPCR) and a functional method (reporter gene expression) used commonly. The RT-qPCR method requires purification of viral RNA and the accuracy of titration therefore depends on the efficiency of purification; this requirement is ameliorated in the hybridization assay as RNA is measured directly in viral lysates. The present study indicates that the hybridization based titration assay performed on viral lysates was more accurate and has additional advantages of being rapid, robust and not dependent on transduction efficiency in different cell types.

Cellular uptake and lysosomal delivery of galactocerebrosidase tagged with the HIV Tat protein transduction domain

A number of studies have shown that a short peptide, the protein transduction domain (PTD) derived from the HIV-1 Tat protein (Tat-PTD) improved cellular uptake in vitro and distribution in vivo of recombinant proteins bearing such PTDs when administered systemically. To investigate the effects of Tat-PTD addition on the subcellular localization of the lysosomal enzyme galactocerebrosidase (GALC, EC 3.2.2.46) and with a view towards designing improved therapeutic strategies for Krabbe disease (globoid cell leukodystrophy), mouse GALC was tagged C-terminally with the Tat-PTD. Compared with unmodified GALC, GALC bearing a Tat-PTD, a myc epitope and 6 consecutive His residues [GALC-TMH (Tat-PTD, a myc epitope and 6 consecutive His residues)] was found to be secreted more efficiently. Also, GALC-TMH was found to be taken up by cells both via mannose-6-phosphate receptor (M6PR)-mediated endocytosis as well as by M6PR-independent mechanisms. GALC-TMH displayed increased M6PR-independent uptake in fibroblasts derived from twitcher mice (a murine model of globoid cell leukodystrophy) and in neurons derived from the mouse brain cortex compared with GALC lacking a Tat-PTD. Immunocytochemical analyses revealed that Tat-modified GALC protein co-localized in part with the lysosome-associated membrane protein-1. Complete correction of galactosylceramide accumulation was achieved in twitcher mouse fibroblasts lacking GALC activity following addition of GALC-TMH. Therefore, GALC-TMH not only maintained the features of the native GALC protein including enzymatic function, intracellular transport and location, but also displayed more efficient cellular uptake.

Lentiviral vectors encoding tetracycline-dependent repressors and transactivators for reversible knockdown of gene expression: a comparative study

Background

RNA interference (RNAi)-mediated by the expression of short hairpin RNAs (shRNAs) has emerged as a powerful experimental tool for reverse genetic studies in mammalian cells. A number of recent reports have described approaches allowing regulated production of shRNAs based on modified RNA polymerase II (Pol II) or RNA polymerase III (Pol III) promoters, controlled by drug-responsive transactivators or repressors such as tetracycline (Tet)-dependent transactivators and repressors. However, the usefulness of these approaches is often times limited, caused by inefficient delivery and/or expression of shRNA-encoding sequences in target cells and/or poor design of shRNAs sequences. With a view toward optimizing Tet-regulated shRNA expression in mammalian cells, we compared the capacity of a variety of hybrid Pol III promoters to express short shRNAs in target cells following lentivirus-mediated delivery of shRNA-encoding cassettes.

Results

RNAi-mediated knockdown of gene expression in target cells, controlled by a modified Tet-repressor (TetR) in the presence of doxycycline (Dox) was robust. Expression of shRNAs from engineered human U6 (hU6) promoters containing a single tetracycline operator (TO) sequence between the proximal sequence element (PSE) and the TATA box, or an improved second-generation Tet-responsive promoter element (TRE) placed upstream of the promoter was tight and reversible as judged using quantitative protein measurements. We also established and tested a novel hU6 promoter system in which the distal sequence element (DSE) of the hU6 promoter was replaced with a second-generation TRE. In this system, positive regulation of shRNA production is mediated by novel Tet-dependent transactivators bearing transactivation domains derived from the human Sp1 transcription factor.

Conclusion

Our modified lentiviral vector system resulted in tight and reversible knockdown of target gene expression in unsorted cell populations. Tightly regulated target gene knockdown was observed with vectors containing either a single TO sequence or a second-generation TRE using carefully controlled transduction conditions. We expect these vectors to ultimately find applications for tight and reversible RNAi in mammalian cells in vivo.

Both HIV- and EIAV-based lentiviral vectors mediate gene delivery to pancreatic cancer cells and human pancreatic primary patient xenografts

Few effective treatments for pancreatic cancer exist, especially for patients with advanced disease. Gene therapy alone, or combined with current treatments, offers an alternative approach. Here we examined the potential of primate and nonprimate lentivectors to mediate gene delivery to this cancer type. VSV-G pseudotyped lentivectors based on human immunodeficiency type-1 virus (HIV-1) and equine infectious anemia virus (EIAV), containing the enhanced green fluorescent protein (EGFP) reporter gene were prepared and characterized for titer and RNA content. Vector-mediated gene delivery was examined in five pancreatic cancer cell lines in vitro, and in MiaPaCa-2 cells as well as in five human primary patient biopsies xenografted subcutaneously in nude mice. While individual cell lines showed differential sensitivities to transduction with lentivectors, all cell lines were successfully transduced with both vector types. Similarly, both vectors transduced MiaPaCa-2 and all of the human primary patient xenografts. We observed 6-29% transduction with HIV-based vectors (n=3 xenografts) and 1.8-30% with EIAV-based vectors (n=4 xenografts). Long-term EIAV-mediated gene expression was recorded in cell lines for up to 6 months. We conclude that these vectors have potential as mediators of clinical gene therapy for pancreatic cancer treatment. Moreover, they are useful laboratory research tools for pancreatic cancer research.

From genetic abnormality to metastases: murine models of breast cancer and their use in the development of anticancer therapies

Numerous mouse models of mammary cancer have been developed that mimic selective aspects of human disease. The use of these models has enabled preclinical chemotherapeutic, chemoprevention, and genetic therapy studies in vivo, the testing of gene delivery systems, and the identification of tumour and metastasis suppressor and inducer genes. This review has discussed the most abundantly used murine models of mammary cancer including: spontaneous tumours, chemically induced tumours, orthotopic and syngeneic tumour transplantation, injected tumours, and genetically engineered mice with a predisposition to neoplasia. Each model has been discussed with regards to its merits and limitations for investigating the genetic and phenotypic alterations involved in the human disease as well as its potential usefulness for the development of new treatment strategies. To date no single mouse model is available with the ability to replicate the entire disease process, however, existing models continue to provide invaluable insights into breast cancer induction and progression that would be impossible to obtain using in vitro models alone.

Gene therapy for lung cancer

Over the past three decades, the molecular biology of lung cancer has been progressively delineated. Concurrently, gene therapy techniques have been developed that allow targeting or replacement of dysfunctional genes in cancer cells, such as activated tumor-promoting oncogenes, inactivated tumor-suppressing, or apoptosis-promoting genes. This article will review the therapeutic implications of molecular changes associated with non-small cell lung cancer and the status of gene therapy.

In vivo transduction of HIV-1-derived lentiviral particles engineered for macrolide-adjustable transgene expression

BACKGROUND

The molecular merger of latest-generation transduction technologies with advanced transgene control modalities may foster decisive advances in therapeutic reprogramming of somatic cell phenotypes.

METHODS

We have engineered self-inactivating HIV-1-based lentiviral expression vectors for reversible macrolide-adjustable transgene expression.

RESULTS

Lentiviral particles engineered for macrolide-responsive human vascular endothelial growth factor 121 (VEGF121) expression compared favourably with isogenic streptogramin- and tetracycline-responsive configurations and showed excellent growth-factor fine-tuning following transduction into a variety of mammalian cell lines and different human primary cells. Chicken embryos transduced for macrolide-controlled VEGF121 production exhibited dose-dependent neovascularization and exemplified lentivector-delivered transgene transcription fine-tuning in vivo.

CONCLUSIONS

Macrolide-adjustable lentivectors enable robust and precise in vitro and in vivo transgene fine-tuning which may give future gene therapy trials a new impetus.

Interferon-alpha gene therapy by lentiviral vectors contrasts ovarian cancer growth through angiogenesis inhibition

Ovarian cancer represents a suitable disease for gene therapy because of the containment of neoplastic cells in the peritoneal cavity even at advanced tumor stages. The aim of this study was to investigate whether intraperitoneal administration of a lentiviral vector encoding murine interferon-alpha (LV-IFN) could have therapeutic activity in a transplantable ovarian cancer model. Multiple injections of low amounts of LV-IFN into severe combined immunodeficiency (SCID) mice bearing IGROV-1 or OC316 ovarian cancer cells elicited remarkable antitumor activity, leading to prolongation of survival in the majority of animals. A definitive cure was obtained in animals bearing PD-OVA#1 tumors, generated by injecting tumor cells isolated from the ascitic fluid of a patient into SCID mice. Interferon-alpha levels were detected in the peritoneal fluids but not in the serum of treated mice, indicating that production of the cytokine is mainly local, by both tumor and normal cells of the host. Antitumor effects were associated with a remarkable decrease in the formation of hemorrhagic ascites, an increase in ischemic tumor necrosis, and a reduction in microvessel density. In conclusion, our findings show that intracavitary IFN-alpha gene therapy, using a lentiviral vector, provides strong antitumor effects in murine models of ovarian cancer and reinforces the evidence that angiogenesis inhibition is a promising strategy for the treatment of localized tumors.

Systemic administration of naked DNA with targeting specificity to mammalian kidneys

A major challenge for gene therapy is to be able to deliver efficiently the gene of interest to specific cell types. Here we describe a safe and simple effective naked DNA gene delivery method, via inferior vena cava (IVC) injection, to the recipient's kidneys. It was further demonstrated that gene expression was concentrated in the proximal tubular epithelial cells of the cortico-medullary region of the kidney. Confocal microscopy analyses demonstrated the presence of the exogenous DNA in the renal cell membrane 10 min postgene delivery. However, it was only by 30 min that the presence of the exogenous DNA could be detected in the cell cytoplasm and in the nuclei of the renal cells. Stable expression of the beta-galactosidase gene could be detected for up to 35 days and no toxicity or any adverse pathological effect associated with the delivery method could be observed. Importantly, this IVC gene delivery method could promote the targeting of genes to carcinoma established in the kidney of SCID mice. These results provide the first evidence to support that stable gene expression could be achieved in the renal cells of kidney and the established carcinoma in the kidneys following in vivo gene delivery with naked DNA and could therefore provide the potential to design protocols for the gene therapy of the kidney diseases.