Alpha-fetoprotein promoter-targeted sodium iodide symporter gene therapy of hepatocellular carcinoma

Applications of tissue-specific and cancer-selective gene promoters for cancer diagnosis and therapy

Current treatment of solid tumors with standard of care chemotherapies, radiation therapy and/or immunotherapies are often limited by severe adverse toxic effects, resulting in a narrow therapeutic index. Cancer gene therapy represents a targeted approach that in principle could significantly reduce undesirable side effects in normal tissues while significantly inhibiting tumor growth and progression. To be effective, this strategy requires a clear understanding of the molecular biology of cancer development and evolution and developing biological vectors that can serve as vehicles to target cancer cells. The advent and fine tuning of omics technologies that permit the collective and spatial recognition of genes (genomics), mRNAs (transcriptomics), proteins (proteomics), metabolites (metabolomics), epiomics (epigenomics, epitranscriptomics, and epiproteomics), and their interactomics in defined complex biological samples provide a roadmap for identifying crucial targets of relevance to the cancer paradigm. Combining these strategies with identified genetic elements that control target gene expression uncovers significant opportunities for developing guided gene-based therapeutics for cancer. The purpose of this review is to overview the current state and potential limitations in developing gene promoter-directed targeted expression of key genes and highlights their potential applications in cancer gene therapy.

Strategies for Targeting Gene Therapy in Cancer Cells With Tumor-Specific Promoters

Cancer is the second cause of death worldwide, surpassed only by cardiovascular diseases, due to the lack of early diagnosis, and high relapse rate after conventional therapies. Chemotherapy inhibits the rapid growth of cancer cells, but it also affects normal cells with fast proliferation rate. Therefore, it is imperative to develop other safe and more effective treatment strategies, such as gene therapy, in order to significantly improve the survival rate and life expectancy of patients with cancer. The aim of gene therapy is to transfect a therapeutic gene into the host cells to express itself and cause a beneficial biological effect. However, the efficacy of the proposed strategies has been insufficient for delivering the full potential of gene therapy in the clinic. The type of delivery vehicle (viral or non viral) chosen depends on the desired specificity of the gene therapy. The first gene therapy trials were performed with therapeutic genes driven by viral promoters such as the CMV promoter, which induces non-specific toxicity in normal cells and tissues, in addition to cancer cells. The use of tumor-specific promoters over-expressed in the tumor, induces specific expression of therapeutic genes in a given tumor, increasing their localized activity. Several cancer- and/or tumor-specific promoters systems have been developed to target cancer cells. This review aims to provide up-to-date information concerning targeting gene therapy with cancer- and/or tumor-specific promoters including cancer suppressor genes, suicide genes, anti-tumor angiogenesis, gene silencing, and gene-editing technology, as well as the type of delivery vehicle employed. Gene therapy can be used to complement traditional therapies to provide more effective treatments.

Molecular Imaging with Reporter Genes: Has Its Promise Been Delivered?

The first reporter systems were developed in the early 1980s and were based on measuring the activity of an enzyme-as a surrogate measure of promoter-driven transcriptional activity-which is now known as a reporter gene system. The initial objective and application of reporter techniques was to analyze the activity of a specific promoter (namely, the expression of a gene that is under the regulation of the specific promoter that is linked to the reporter gene). This system allows visualization of specific promoter activity with great sensitivity. In general, there are 2 classes of reporter systems: constitutively expressed (always-on) reporter constructs used for cell tracking, and inducible reporter systems sensitive to endogenous signaling molecules and transcription factors that characterize specific tissues, tumors, or signaling pathways.This review traces the development of different reporter systems, using fluorescent and bioluminescent proteins as well as radionuclide-based reporter systems. The development and application of radionuclide-based reporter systems is the focus of this review. The question at the end of the review is whether the "promise" of reporter gene imaging has been realized. What is required for moving forward with radionuclide-based reporter systems, and what is required for successful translation to clinical applications?

Dual-targeted NIS polyplexes-a theranostic strategy toward tumors with heterogeneous receptor expression

Tumor heterogeneity, within and between tumors, may have severe implications for tumor therapy, especially for targeted gene therapy, where single-targeted approaches often result in limited efficacy and therapy resistance. Polymer-formulated nonviral vectors provide a potent delivery platform for cancer therapy. To improve applicability for future clinical use in a broad range of patients and cancer types, a dual-targeting approach was performed. Synthetic LPEI-PEG2kDa-based polymer backbones were coupled to two tumor-specific peptide ligands GE11 (EGFR-targeting) and cMBP (cMET-targeting). The dual-targeting approach was used to deliver the theranostic sodium iodide symporter (NIS) gene to hepatocellular cancer. NIS as auspicious theranostic gene allows noninvasive imaging of functional NIS gene expression and effective anticancer radioiodide therapy. Enhanced tumor-specific transduction efficiency of dual-targeted polyplexes compared to single-targeted polyplexes was demonstrated in vitro using tumor cell lines with different EGFR and cMET expression and in vivo by 124I-PET-imaging. Therapeutic efficacy of the bispecific concept was mirrored by significantly reduced tumor growth and perfusion, which was associated with prolonged animal survival. In conclusion, the dual-targeting approach highlights the benefits of a bifunctional strategy for a future clinical translation of the bioimaging-based NIS-mediated radiotherapy allowing efficient targeting of heterogeneic tumors with variable receptor expression levels.

Systemic tumor-targeted sodium iodide symporter (NIS) gene therapy of hepatocellular carcinoma mediated by B6 peptide polyplexes

BACKGROUND

Nonviral polymer-based gene transfer represents an adaptable system for tumor-targeted gene therapy because various design strategies of shuttle systems, together with the mechanistic concept of active tumor targeting, lead to improved gene delivery vectors resulting in higher tumor specificity, efficacy and safety.

METHODS

Using the sodium iodide symporter (NIS) as a theranostic gene, nonviral gene delivery vehicles based on linear polyethylenimine (LPEI), polyethylene glycol (PEG) and coupled to the synthetic peptide B6 (LPEI-PEG-B6), which specifically binds to tumor cells, were investigated in a hepatocellular carcinoma xenograft model for tumor selectivity and transduction efficiency.

RESULTS

In vitro incubation of three different tumor cell lines with LPEI-PEG-B6/NIS resulted in significant increase in iodide uptake activity compared to untargeted and empty vectors. After establishment of subcutaneous HuH7 tumors, NIS-conjugated nanoparticles were injected intravenously followed by analysis of radioiodide biodistribution using ¹²³ I-scintigraphy showing significant perchlorate-sensitive iodide accumulation in tumors of LPEI-PEG-B6/NIS-treated mice (8.0 ± 1.5% ID/g ¹²³ I; biological half-life of 4 h). After four cycles of repetitive polyplex/¹³¹ I applications, a significant delay of tumor growth was observed, which was associated with markedly improved survival in the therapy group.

CONCLUSIONS

These results clearly demonstrate that systemic in vivo NIS gene transfer using nanoparticle vectors coupled to B6 tumor targeting ligand is capable of inducing tumor-specific radioiodide uptake. This promising gene therapy approach opens the exciting prospect of NIS-mediated radionuclide therapy in metastatic cancer, together with the possibility of combining several targeting ligands to enhance selective therapeutic efficacy in a broad field of cancer types with various receptor expression profiles.

EGFR-targeted nonviral NIS gene transfer for bioimaging and therapy of disseminated colon cancer metastases

Liver metastases present a serious problem in the therapy of advanced colorectal cancer (CRC), as more than 20% of patients have distant metastases at the time of diagnosis with less than 5% being cured. Consequently, new therapeutic approaches are of major need together with high-resolution imaging methods that allow highly specific detection of small metastases.

The unique combination of reporter and therapy gene function of the sodium iodide symporter (NIS) may represent a promising theranostic strategy for CRC liver metastases allowing non-invasive imaging of functional NIS expression and therapeutic application of ¹³¹I.

For targeted NIS gene transfer polymers containing linear polyethylenimine (LPEI), polyethylene glycol (PEG) and the epidermal growth factor receptor (EGFR)-specific ligand GE11 were complexed with human NIS DNA (LPEI-PEG-GE11/NIS). Tumor specificity and transduction efficiency were examined in high EGFR-expressing LS174T metastases by non-invasive imaging using ¹⁸F-tetrafluoroborate (¹⁸F-TFB) as novel NIS PET tracer. Mice that were injected with LPEI-PEG-GE11/NIS 48 h before ¹⁸F-TFB application showed high tumoral levels (4.8±0.6% of injected dose) of NIS-mediated radionuclide uptake in comparison to low levels detected in mice that received untargeted control polyplexes. Three cycles of intravenous injection of EGFR-targeted NIS polyplexes followed by therapeutic application of 55.5 MBq ¹³¹I resulted in marked delay in metastases spread, which was associated with improved animal survival.

In conclusion, these preclinical data confirm the enormous potential of EGFR-targeted synthetic polymers for systemic NIS gene delivery in an advanced multifocal CRC liver metastases model and open the exciting prospect of NIS-mediated radionuclide therapy in metastatic disease.

Alpha-fetoprotein-targeted reporter gene expression imaging in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers in Eastern Asia, and its incidence is increasing globally. Numerous experimental models have been developed to better our understanding of the pathogenic mechanism of HCC and to evaluate novel therapeutic approaches. Molecular imaging is a convenient and up-to-date biomedical tool that enables the visualization, characterization and quantification of biologic processes in a living subject. Molecular imaging based on reporter gene expression, in particular, can elucidate tumor-specific events or processes by acquiring images of a reporter gene’s expression driven by tumor-specific enhancers/promoters. In this review, we discuss the advantages and disadvantages of various experimental HCC mouse models and we present in vivo images of tumor-specific reporter gene expression driven by an alpha-fetoprotein (AFP) enhancer/promoter system in a mouse model of HCC. The current mouse models of HCC development are established by xenograft, carcinogen induction and genetic engineering, representing the spectrum of tumor-inducing factors and tumor locations. The imaging analysis approach of reporter genes driven by AFP enhancer/promoter is presented for these different HCC mouse models. Such molecular imaging can provide longitudinal information about carcinogenesis and tumor progression. We expect that clinical application of AFP-targeted reporter gene expression imaging systems will be useful for the detection of AFP-expressing HCC tumors and screening of increased/decreased AFP levels due to disease or drug treatment.

Sequence-defined cMET/HGFR-targeted Polymers as Gene Delivery Vehicles for the Theranostic Sodium Iodide Symporter (NIS) Gene

The sodium iodide symporter (NIS) as well-characterized theranostic gene represents an outstanding tool to target different cancer types allowing noninvasive imaging of functional NIS expression and therapeutic radioiodide application. Based on its overexpression on the surface of most cancer types, the cMET/hepatocyte growth factor receptor serves as ideal target for tumor-selective gene delivery. Sequence-defined polymers as nonviral gene delivery vehicles comprising polyethylene glycol (PEG) and cationic (oligoethanoamino) amide cores coupled with a cMET-binding peptide (cMBP2) were complexed with NIS-DNA and tested for receptor-specificity, transduction efficiency, and therapeutic efficacy in hepatocellular cancer cells HuH7. In vitro iodide uptake studies demonstrated high transduction efficiency and cMET-specificity of NIS-encoding polyplexes (cMBP2-PEG-Stp/NIS) compared to polyplexes without targeting ligand (Ala-PEG-Stp/NIS) and without coding DNA (cMBP2-PEG-Stp/Antisense-NIS). Tumor recruitment and vector biodistribution were investigated in vivo in a subcutaneous xenograft mouse model showing high tumor-selective iodide accumulation in cMBP2-PEG-Stp/NIS-treated mice (6.6 ± 1.6% ID/g (123)I, biological half-life 3 hours) by (123)I-scintigraphy. Therapy studies with three cycles of polyplexes and (131)I application resulted in significant delay in tumor growth and prolonged survival. These data demonstrate the enormous potential of cMET-targeted sequence-defined polymers combined with the unique theranostic function of NIS allowing for optimized transfection efficiency while eliminating toxicity.

Infection by Cx43 adenovirus increased chemotherapy sensitivity in human gastric cancer BGC-823 cells: not involving in induction of cell apoptosis

BACKGROUND AND OBJECTIVE

There is a lower basal expression of Connexin43 (Cx43) in human gastric cancer BGC-823 cells. In the present study, BGC-823 cells were transfected with recombinant Cx43 adenovirus plasmid vector, and we explored the influences of Cx43 expression on cell proliferation, chemo-sensitivity, colony forming ability, invasion ability and apoptosis. Moreover, we also determined the expression of Pgp, Cx43, as well as apoptosis-related proteins (bcl-2, bax, caspase3 and caspase 9).

METHODS

MTT assay was performed to determine the proliferation of BGC-823 cells before and after Cx43 transfection. The influences of Cx43 infection on sensitivity of chemotherapy (including Doxorubicin, fluorouracil, oxaliplatin) were detected by MTT assay. Expression levels of Pgp, Cx43, as well as apoptosis-related proteins (bcl-2, bax, caspase-3 and caspase-9) in BGC-823 cells were determined by Western blotting analysis before and after the infection with Cx43 adenovirus. MDR expression was determined by RT-PCR before and after Cx43 infection. Invasive ability was detected by invasion chamber. Influence of Cx43 adenovirus infection on apoptosis of BGC-823 cells was determined by flow cytometry.

RESULTS

After infection by Cx43 adenovirus, colony forming rate and invasive ability of BGC-823 cells were decreased. Flow cytometry results revealed that cell apoptosis were insignificantly increased. The data of MTT assay revealed that infection with Cx43 adenovirus, cell proliferation ability decreased and sensitivity to chemotherapy drugs (including doxorubicin, fluorouracil, oxaliplatin) increased. Results of Western blotting analysis revealed that increasing expression levels of Cx43, decreasing expression levels of Pgp, and insignificant changes of bcl-2, bax, caspase3 and caspase 9 were detected. RT-PCR revealed the expression of MDR1 gene, the gene encoding Pgp, decreased significantly (p<0.05).

CONCLUSION

The human gastric cancer BGC-823 cells were infected with Cx43-IRES2-EGFP recombinant adenovirus vector. Colony formation, invasive ability and cell proliferation all decreased, whereas chemo-sensitivity increased in Cx43 infected BGC-823 cells. The increasing Cx43 expression was accompanied by decreasing Pgp expression and MDR1 m RNA levels. However, apoptosis-related proteins (bcl-2, bax, caspase3 and caspase 9) and cell apoptosis increased insignificantly. All results demonstrated that Cx43 may be negatively regulated the development, invasion and metastasis of gastric cancers, however, it had no obvious relationship with tumor cell apoptosis.

Mesenchymal stem cell-mediated, tumor stroma-targeted radioiodine therapy of metastatic colon cancer using the sodium iodide symporter as theranostic gene

The tumor-homing property of mesenchymal stem cells (MSCs) allows targeted delivery of therapeutic genes into the tumor microenvironment. The application of sodium iodide symporter (NIS) as a theranostic gene allows noninvasive imaging of MSC biodistribution and transgene expression before therapeutic radioiodine application. We have previously shown that linking therapeutic transgene expression to induction of the chemokine CCL5/RANTES allows a more focused expression within primary tumors, as the adoptively transferred MSC develop carcinoma-associated fibroblast-like characteristics. Although RANTES/CCL5-NIS targeting has shown efficacy in the treatment of primary tumors, it was not clear if it would also be effective in controlling the growth of metastatic disease.

METHODS

To expand the potential range of tumor targets, we investigated the biodistribution and tumor recruitment of MSCs transfected with NIS under control of the RANTES/CCL5 promoter (RANTES-NIS-MSC) in a colon cancer liver metastasis mouse model established by intrasplenic injection of the human colon cancer cell line LS174t. RANTES-NIS-MSCs were injected intravenously, followed by (123)I scintigraphy, (124)I PET imaging, and (131)I therapy.

RESULTS

Results show robust MSC recruitment with RANTES/CCL5-promoter activation within the stroma of liver metastases as evidenced by tumor-selective iodide accumulation, immunohistochemistry, and real-time polymerase chain reaction. Therapeutic application of (131)I in RANTES-NIS-MSC-treated mice resulted in a significant delay in tumor growth and improved overall survival.

CONCLUSION

This novel gene therapy approach opens the prospect of NIS-mediated radionuclide therapy of metastatic cancer after MSC-mediated gene delivery.

Assessment of α-fetoprotein targeted HSV1-tk expression in hepatocellular carcinoma with in vivo imaging

Tumor-specific enhancer/promoter is applicable for targeting gene expression in tumors and helpful for tumor-targeting imaging and therapy. We aimed to acquire α-fetoprotein (AFP)-producing hepatocellular carcinoma (HCC) specific images using adenovirus containing HSV1-tk gene controlled by AFP enhancer/promoter and evaluate in vivo ganciclovir (GCV)-medicated therapeutic effects on AFP-targeted HSV1-tk expression with (18)F-FDG positron emission tomography (PET). Recombinant adenovirus expressing HSV1-tk under AFP enhancer/promoter was produced (AdAFP-TK) and the expression levels were evaluated by RT-PCR and (125)I-IVDU uptake. GCV-mediated HSV1-tk cytotoxicity was determined by MTT assay. After the mixture of AdAFP-fLuc and AdAFP-TK was administrated, bioluminescent images (BLIs) and (18)F-FHBG PET images were obtained in tumor-bearing mice. In vivo therapeutic effects of AdAFP-TK and GCV in the HuH-7 xenograft model were monitored by (18)F-FDG PET. When infected with AdAFP-TK, cell viability in HuH-7 was reduced, but those in HT-29 and SK-Hep-1 were not significantly decreased at any GCV concentration less than 100 μM. AFP-targeted fLuc and HSV1-tk expression were clearly visualized by BLI and (18)F-FHBG PET images in AFP-producing HCC, respectively. In vivo GCV-mediated tumor growth inhibition by AFP-targeted HSV1-tk expression was monitored by (18)F-FDG PET. Recombinant AdAFP-TK could be applied for AFP-targeted HCC gene therapy and imaging in AFP-producing HCC.

SIRT1-metabolite binding histone macroH2A1.1 protects hepatocytes against lipid accumulation

Non-alcoholic-fatty-liver-disease (NAFLD) encompasses conditions associated to fat deposition in the liver, which are generally deteriorated during the aging process. MacroH2A1, a variant of histone H2A, is a key transcriptional regulator involved in tumorigenic processes and cell senescence, and featuring two alternatively splicing isoforms, macroH2A1.1 and macroH2A1.2. MacroH2A1.1 binds with high affinity O-acetyl ADP ribose, a small metabolite produced by the reaction catalysed by NAD+-dependent deacetylase SIRT1, whereas macroH2A1.2 is unable to do so. The functional significance of this binding is unknown. We previously reported that the hepatic levels of macroH2A1.1 and macroH2A1.2 are differentially expressed in mice models of NAFLD. Here we show that over-expression of macroH2A1.1, but not of macroH2A1.2, is able to protect hepatocytes against lipid accumulation. MacroH2A1.1 over-expressing cells display ameliorated glucose metabolism, reduced expression of lipidogenic genes and fatty acids content. SIRT1/macroH2A1.1-dependent epigenetic regulation of lipid metabolism may be relevant to NAFLD development.

Combination of hepatocyte specific delivery and transformation dependent expression of shRNA inducing transcriptional gene silencing of c-Myc promoter in hepatocellular carcinoma cells

Background

A specific targeting modality for hepatocellular carcinoma (HCC) could ideally encompass a liver cell specific delivery system of a transcriptional unit that is active only in neoplastic cells. Sendai virosomes, derived from Sendai viral envelopes, home to hepatocytes based on the liver specific expression of asialoglycoprotein receptors (ASGPRs) which are recognized by the Sendai virosomal fusion (F) proteins. As reported earlier by us and other groups, transcriptional gene silencing (TGS) does not require continuous presence of the effector siRNA/shRNA molecule and is heritable, involving epigenetic modifications, leading to long term transcriptional repression. This could be advantageous over conventional gene therapy approaches, since continuous c-Myc inactivation is required to suppress hepatocarcinoma cells.

Methods

Exploiting such virosomal delivery, the alpha-fetoprotein (AFP) promoter, in combination with various tumour specific enhancers, was used to drive the expression of shRNA directed against ME1a1 binding site of the proto-oncogene c-Myc P2 promoter, in order to induce TGS in neoplastic liver cells.

Results

The dual specificity achieved by the Sendai virosomal delivery system and the promoter/enhancer guided expression ensured that the shRNA inducing TGS was active only in liver cells that had undergone malignant transformation. Our results indicate that such a bimodal therapeutic system induced specific activation of apoptosis in hepatocarcinoma cells due to heterochromatization and increased DNA methylation of the CpG islands around the target loci.

Conclusions

The Sendai virosomal delivery system, combined with AFP promoter/enhancer expression machinery, could serve as a generalized mechanism for the expression of genes deleterious to transformed hepatocarcinoma cells. In this system, the epigenetic suppression of c-Myc could have an added advantage for inducing cell death in the targeted cells.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-582) contains supplementary material, which is available to authorized users.

Sodium iodide symporter (NIS) in extrathyroidal malignancies: focus on breast and urological cancer

Background

Expression and function of sodium iodide symporter (NIS) is requisite for efficient iodide transport in thyrocytes, and its presence in cancer cells allows the use of radioiodine as a diagnostic and therapeutic tool in thyroid neoplasia. Discovery of NIS expression in extrathyroidal tissues, including transformed cells, has opened a novel field of research regarding NIS-expressing extrathyroidal neoplasia. Indeed, expression of NIS may be used as a biomarker for diagnostic, prognostic, and therapeutic purposes. Moreover, stimulation of endogenous NIS expression may permit the radioiodine treatment of extrathyroidal lesions by concentrating this radioisotope.

Results

This review describes recent findings in NIS research in extrathyroidal malignancies, focusing on breast and urological cancer, emphasizing the most relevant developments that may have clinical impact.

Conclusions

Given the recent progress in the study of NIS regulation as molecular basis for new therapeutic approaches in extrathyroidal cancers, particular attention is given to studies regarding the relationship between NIS and clinical-pathological aspects of the tumors and the regulation of NIS expression in the experimental models.

Characteristic variation of α-fetoprotein DNA nanometer-range irradiated by iodine-125

To obtain the characteristic variation of structure and functional groups of α-fetoprotein (AFP) DNA irradiated by iodine-125((125)I), the AFP antisense oligonucleotide labeled with various radioactivity dose (125)I was mixed with the AFP DNA in a simulated polymerase chain reaction temperature condition. After the mixtures were irradiated by the (125)I from 2 to 72 hours, the mutation of the biogenic conformation and functional groups of the irradiated DNA were investigated using laser Raman spectroscopy. The shifted peak and the decreased intensity of the characteristic Raman spectra were found, which demonstrated that the structure of the phosphodiester linkage was broke, the pyridine and purine bases in DNA emerged and damaged. The model of gene conformation changed from form B to form C spectrum after the nanometer-range irradiation with (125)I from 2 to 24 hours. The damage of local pyridine and purine bases gradually increased along with the accumulation of irradiation, and the bases and ribosome were finally dissociated and stacked.

The Na+/I- symporter (NIS): mechanism and medical impact

The Na(+)/I(-) symporter (NIS) is the plasma membrane glycoprotein that mediates active I(-) transport in the thyroid and other tissues, such as salivary glands, stomach, lactating breast, and small intestine. In the thyroid, NIS-mediated I(-) uptake plays a key role as the first step in the biosynthesis of the thyroid hormones, of which iodine is an essential constituent. These hormones are crucial for the development of the central nervous system and the lungs in the fetus and the newborn and for intermediary metabolism at all ages. Since the cloning of NIS in 1996, NIS research has become a major field of inquiry, with considerable impact on many basic and translational areas. In this article, we review the most recent findings on NIS, I(-) homeostasis, and related topics and place them in historical context. Among many other issues, we discuss the current outlook on iodide deficiency disorders, the present stage of understanding of the structure/function properties of NIS, information gleaned from the characterization of I(-) transport deficiency-causing NIS mutations, insights derived from the newly reported crystal structures of prokaryotic transporters and 3-dimensional homology modeling, and the novel discovery that NIS transports different substrates with different stoichiometries. A review of NIS regulatory mechanisms is provided, including a newly discovered one involving a K(+) channel that is required for NIS function in the thyroid. We also cover current and potential clinical applications of NIS, such as its central role in the treatment of thyroid cancer, its promising use as a reporter gene in imaging and diagnostic procedures, and the latest studies on NIS gene transfer aimed at extending radioiodide treatment to extrathyroidal cancers, including those involving specially engineered NIS molecules.

Suppression of orthotopically implanted hepatocarcinoma in mice by umbilical cord-derived mesenchymal stem cells with sTRAIL gene expression driven by AFP promoter

Mesenchymal stem cells (MSCs) are promising vehicles for delivering therapeutic agents in tumor therapy. Human umbilical cord-derived mesenchymal stem cells (HUMSCs) resemble bone marrow-derived MSCs with respect to hepatic differentiation potential in injured livers in animals, while their hepatic differentiation under the hepatocarcinoma microenvironment is unclear. In this study, HUMSCs were isolated and transduced by lentiviral vectors coding the soluble human tumor necrosis factor-related apoptosis-inducing ligand (sTRAIL) gene driven by alpha-fetoprotein (AFP) promoter to investigate the therapeutic effects of these HUMSC against orthotopically implanted hepatocarcinoma in mice. We showed that HUMSCs can be transduced by lentivirus efficiently. HUMSCs developed cuboidal morphology, and expressed AFP and albumin in a two-step protocol. HUMSCs were capable of migrating to hepatocarcinoma in vitro as well as in vivo. In the orthotopical hepatocarcinoma microenvironment, the AFP promoter was activated during the early hepatic differentiation of HUMSCs. After intravenous injected, MSC.AFPILZ-sTRAIL expressed sTRAIL exclusively at the tumor site, and exhibited significant antitumor activity. This effect was stronger when in combination with 5-FU. The treatment was tolerated well in mice. Collectively, our results provide a potential strategy for targeted tumor therapy relying on the use of the tumor tropism and specific differentiation of HUMSCs as vehicles.

Stromal targeting of sodium iodide symporter using mesenchymal stem cells allows enhanced imaging and therapy of hepatocellular carcinoma

The tumor-homing property of mesenchymal stem cells (MSC) has lead to their use as delivery vehicles for therapeutic genes. The application of the sodium iodide symporter (NIS) as therapy gene allows noninvasive imaging of functional transgene expression by (123)I-scintigraphy or PET-imaging, as well as therapeutic application of (131)I or (188)Re. Based on the critical role of the chemokine RANTES (regulated on activation, normal T-cell expressed and presumably secreted)/CCL5 secreted by MSCs in the course of tumor stroma recruitment, use of the RANTES/CCL5 promoter should allow tumor stroma-targeted expression of NIS after MSC-mediated delivery. Using a human hepatocellular cancer (HCC) xenograft mouse model (Huh7), we investigated distribution and tumor recruitment of RANTES-NIS-engineered MSCs after systemic injection by gamma camera imaging. (123)I-scintigraphy revealed active MSC recruitment and CCL5 promoter activation in the tumor stroma of Huh7 xenografts (6.5% ID/g (123)I, biological half-life: 3.7 hr, tumor-absorbed dose: 44.3 mGy/MBq). In comparison, 7% ID/g (188)Re was accumulated in tumors with a biological half-life of 4.1 hr (tumor-absorbed dose: 128.7 mGy/MBq). Administration of a therapeutic dose of (131)I or (188)Re (55.5 MBq) in RANTES-NIS-MSC-treated mice resulted in a significant delay in tumor growth and improved survival without significant differences between (131)I and (188)Re. These data demonstrate successful stromal targeting of NIS in HCC tumors by selective recruitment of NIS-expressing MSCs and by use of the RANTES/CCL5 promoter. The resulting tumor-selective radionuclide accumulation was high enough for a therapeutic effect of (131)I and (188)Re opening the exciting prospect of NIS-mediated radionuclide therapy of metastatic cancer using genetically engineered MSCs as gene delivery vehicles.

Generation of a tumor- and tissue-specific episomal non-viral vector system

Background

A key issue for safe and reproducible gene therapy approaches is the autologous and tissue-specific expression of transgenes. Tissue-specific expression in vivo is either achieved by transfer vectors that deliver the gene of interest into a distinct cell type or by use of tissue-specific expression cassettes. Here we present the generation of non-viral, episomally replicating vectors that are able to replicate in a tissue specific manner thus allowing tissue specific transgene expression in combination with episomal replication. The episomal replication of the prototype vector pEPI-1 and its derivatives depends exclusively on a transcription unit starting from a constitutively active promoter extending into the scaffold/matrix attachment region (S/MAR).

Results

Here, we exchanged the constitutive promoter in the pEPI derivative pEPito by the tumor specific alpha fetoprotein (AFP) or the muscle specific smooth muscle 22 (SM22) promoter leading to specific transgene expression in AFP positive human hepatocellular carcinoma (HUH7) and in a SM22 positive cell line, respectively. The incorporation of the hCMV enhancer element into the expression cassette further boosted the expression levels with both promoters. Tissue specific-replication could be exemplary proven for the smooth muscle protein 22 (SM22) promoter in vitro. With the AFP promoter-driven pEPito vector hepatocellular carcinoma-specific expression could be achieved in vivo after systemic vector application together with polyethylenimine as transfection enhancer.

Conclusions

In this study we present an episomal plasmid system designed for tissue specific transgene expression and replication. The human AFP-promoter in combination with the hCMV enhancer element was demonstrated to be a valuable tissue-specific promoter for targeting hepatocellular carcinomas with non-viral gene delivery system, and tissue specific replication could be shown in vitro with the muscle specific SM22 promoter. In combination with appropriate delivery systems, the tissue specific pEPito vector system will allow higher tissue-specificity with less undesired side effects and is suitable for long term transgene expression in vivo within gene therapeutical approaches.

Adrenal gland infection by serotype 5 adenovirus requires coagulation factors

Recombinant, replication-deficient serotype 5 adenovirus infects the liver upon in vivo, systemic injection in rodents. This infection requires the binding of factor X to the capsid of this adenovirus. Another organ, the adrenal gland is also infected upon systemic administration of Ad, however, whether this infection is dependent on the cocksackie adenovirus receptor (CAR) or depends on the binding of factor X to the viral capsid remained to be determined. In the present work, we have used a pharmacological agent (warfarin) as well as recombinant adenoviruses lacking the binding site of Factor X to elucidate this mechanism in mice. We demonstrate that, as observed in the liver, adenovirus infection of the adrenal glands in vivo requires Factor X. Considering that the level of transduction of the adrenal glands is well-below that of the liver and that capsid-modified adenoviruses are unlikely to selectively infect the adrenal glands, we have used single-photon emission computed tomography (SPECT) imaging of gene expression to determine whether local virus administration (direct injection in the kidney) could increase gene transfer to the adrenal glands. We demonstrate that direct injection of the virus in the kidney increases gene transfer in the adrenal gland but liver transduction remains important. These observations strongly suggest that serotype 5 adenovirus uses a similar mechanism to infect liver and adrenal gland and that selective transgene expression in the latter is more likely to be achieved through transcriptional targeting.

In vivo bioluminescent imaging of α-fetoprotein-producing hepatocellular carcinoma in the diethylnitrosamine-treated mouse using recombinant adenoviral vector

BACKGROUND

The in vivo molecular imaging method is a useful tool for monitoring carcinogenesis in various hepatocellular carcinoma (HCC) models, such as xenografted-, chemical induced- and transgenic mice. The tumor-specific gene expression strategy, such as transcriptional targeting, is essential for achieving a lower toxicity for normal liver tissue in therapy and the monitoring of tumor progression in diagnosis, respectively. The present study aimed to visualize spontaneously developing α-fetoprotein (AFP)-producing HCC through targeted gene expression in tumors using recombinant adenoviral vector.

METHODS

The recombinant adenovirus vector, AdAFPfLuc (containing firefly luciferase gene driven by human AFP enhancer/promoter) was prepared. After in vitro infection by adenovirus, gene expression was confirmed using the luciferase assay, semi-quantitative reverse transcriptase-polymerase chain reaction and western blotting in AFP-producing and nonproducing cells. Tumor-bearing mice were intravenously injected with adenovirus, and bioluminescent images were obtained.

RESULTS

The expression of fLuc was efficiently demonstrated by the luciferase assay in AFP-producing cells but not in AFP-nonproducing cells. AFP-producing HCC targeted gene expression was confirmed at the mRNA and protein levels. After being injected intravenously in HuH-7 xenografts and HCC-bearing diethylnitrosamine-treated mice using adenovirus, functional reporter gene expression was confirmed in tumors by in vivo bioluminescent imaging (BLI).

CONCLUSIONS

The recombinant adenovirus vector system can be used to monitor spontaneously developing AFP-producing HCC and to evaluate targeted gene expression in tumors by in vivo BLI in a small animal model.

The EIIAPA chimeric promoter for tumor specific gene therapy of hepatoma

PURPOSE

For targeted imaging and therapy of hepatocellular carcinoma (HCC), we established a chimeric promoter (EIIAPA) containing alpha-fetoprotein (AFP) promoter and hepatitis B virus enhancer II (EIIA) to control downstream expression of reporter and therapeutic genes.

PROCEDURES

We combined AFP promoter and EIIA to establish a chimeric EIIAPA promoter, then developed a bi-cistronic plasmid vector containing HSV1-tk and luciferase genes controlled by EIIAPA to stably transfect HCC cells. The selective transcriptional activity of EIIAPA was assayed by bioluminescence imaging (BLI) and the function of EIIAPA was determined by in vivo microPET and BLI.

RESULTS

The luciferase expression driven by EIIAPA was higher than that driven by AFP promoter in HCC cell lines. EIIAPA-tk induced cytotoxicity was observed only in HepG2 cells. Accumulation of ¹³¹I-FIAU and bioluminescent signal were detected on HepG2 tumors but not in parental tumors. The HepG2 tumors derived from lentiviral-transduced EIIAPA-tk expressing cells accumulated ¹²⁴I-FIAU whereas the ARO tumors did not. The transfected HepG2 tumors expressed adequate EIIAPA-controlled HSV1-TK and the tumor regressed after ganciclovir treatment.

CONCLUSION

The chimeric EIIAPA is a potential candidate promoter for targeted imaging and gene therapy of HCC.

Gene therapy of pancreatic cancer targeting the K-Ras oncogene

Ras mutations are present in ∼95% of pancreatic cancer (PC) cases leading to increased proliferation and apoptosis resistance. The aim of this study is to selectively kill Ras-transformed cells by overexpressing the pro-apoptotic protein, p53 upregulated modulator of apoptosis (PUMA) under a Ras-responsive promoter. Colo357, Panc1 and MiaPaca, PC cell lines harboring K-Ras mutations, normal rat IEC18 enterocytes, and their K-Ras transformed R1 counterparts, were tested. We constructed adenoviral vectors containing the PUMA gene downstream to: (1) Four or five repetitive Ras-responsive elements (Ad-PY4/PY5-PUMA) and (2) a negative control (Ad-SV40-PUMA). Cell viability was estimated by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and apoptosis was evaluated by FACS. In vivo potency of the adenoviruses was evaluated in athymic nude mice. Infection with Ad-PY4/PY5-PUMA markedly inhibited cell growth (∼40-50%), and apoptosis was detected in all cells with high Ras activity, whereas IEC18 cells remained unaffected. The control vector, Ad-SV40-PUMA, did not induce any cell death. Selective and high expression of PUMA was detected in Ad-PY4-PUMA-infected cells. In vivo, Ad-PY4-PUMA inhibited by ∼35% the growth of established tumors compared with the Ad-SV40-PUMA. Selective overexpression of PUMA efficiently inhibits the growth of Ras-transformed cells while sparing the normal ones. This treatment modality may become a useful, effective and safe approach to selectively target Ras-mutated tumor cells.

Sodium iodide symporter (NIS)-mediated radiovirotherapy of hepatocellular cancer using a conditionally replicating adenovirus

In this study, we determined the in vitro and in vivo efficacy of sodium iodide symporter (NIS) gene transfer and the therapeutic potential of oncolytic virotherapy combined with radioiodine therapy using a conditionally replicating oncolytic adenovirus. For this purpose, we used a replication-selective adenovirus in which the E1a gene is driven by the mouse alpha-fetoprotein (AFP) promoter and the human NIS gene is inserted in the E3 region (Ad5-E1/AFP-E3/NIS). Human hepatocellular carcinoma cells (HuH7) infected with Ad5-E1/AFP-E3/NIS concentrated radioiodine at a level that was sufficiently high for a therapeutic effect in vitro. In vivo experiments demonstrated that 3 days after intratumoral (i.t.) injection of Ad5-E1/AFP-E3/NIS HuH7 xenograft tumors accumulated approximately 25% ID g(-1) (percentage of the injected dose per gram tumor tissue) (123)I as shown by (123)I gamma camera imaging. A single i.t. injection of Ad5-E1/AFP-E3/NIS (virotherapy) resulted in a significant reduction of tumor growth and prolonged survival, as compared with injection of saline. Combination of oncolytic virotherapy with radioiodine treatment (radiovirotherapy) led to an additional reduction of tumor growth that resulted in markedly improved survival as compared with virotherapy alone. In conclusion, local in vivo NIS gene transfer using a replication-selective oncolytic adenovirus is able to induce a significant therapeutic effect, which can be enhanced by additional (131)I application.

In vitro radionuclide therapy and in vivo scintigraphic imaging of alpha-fetoprotein-producing hepatocellular carcinoma by targeted sodium iodide symporter gene expression

PURPOSE

This study aimed to develop a gene expression targeting method for specific imaging and therapy of alpha-fetoprotein (AFP)-producing hepatocellular carcinoma (HCC) cells, using an adenovirus vector containing the human sodium/iodide symporter (hNIS) gene driven by an AFP enhancer/promoter.

METHODS

The recombinant adenovirus vector, AdAFPhNIS (containing the hNIS gene driven by human AFP enhancer/promoter) was prepared. After in vitro infection by the adenovirus, hNIS gene expression in AFP-producing cells and in AFP-nonproducing cells was investigated using (125)I uptake assay and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The killing effect of (131)I on AdAFPhNIS-infected HCC cells was studied using an in vitro clonogenic assay. In addition, tumor-bearing mice were intravenously injected with the adenovirus, and scintigraphic images were obtained.

RESULTS

The expression of hNIS was efficiently demonstrated by (125)I uptake assay in AFP-producing cells, but not in AFP-nonproducing cells. AFP-producing HCC-targeted gene expression was confirmed at the mRNA level. Furthermore, in vitro clonogenic assay showed that hNIS gene expression induced by AdAFPhNIS infection in AFP-producing cells caused more sensitivity to (131)I than that in AFP-nonproducing cells. Injected intravenously in HuH-7 tumor xenografts mice by adenovirus, the functional hNIS gene expression was confirmed in tumor by in vivo scintigraphic imaging.

CONCLUSIONS

An AFP-producing HCC was targeted with an adenovirus vector containing the hNIS gene using the AFP enhancer/promoter in vitro and in vivo. These findings demonstrate that AFP-producing HCC-specific molecular imaging and radionuclide gene therapy are feasible using this recombinant adenovirus vector system.

The sodium iodide symporter (NIS) as an imaging reporter for gene, viral, and cell-based therapies

Preclinical and clinical tomographic imaging systems increasingly are being utilized for non-invasive imaging of reporter gene products to reveal the distribution of molecular therapeutics within living subjects. Reporter gene and probe combinations can be employed to monitor vectors for gene, viral, and cell-based therapies. There are several reporter systems available; however, those employing radionuclides for positron emission tomography (PET) or singlephoton emission computed tomography (SPECT) offer the highest sensitivity and the greatest promise for deep tissue imaging in humans. Within the category of radionuclide reporters, the thyroidal sodium iodide symporter (NIS) has emerged as one of the most promising for preclinical and translational research. NIS has been incorporated into a remarkable variety of viral and non-viral vectors in which its functionality is conveniently determined by in vitro iodide uptake assays prior to live animal imaging. This review on the NIS reporter will focus on 1) differences between endogenous NIS and heterologously-expressed NIS, 2) qualitative or comparative use of NIS as an imaging reporter in preclinical and translational gene therapy, oncolytic viral therapy, and cell trafficking research, and 3) use of NIS as an absolute quantitative reporter.

Activity and tumor specificity of human heparanase gene core promoter

Heparanase (HPSE) plays a critical role in tumor metastasis and vascularization. In addition, the human HPSE promoter has been cloned and characterized. However, the activity and specificity of the HPSE promoter in tumor cells remains unclear. The core fragment of the HPSE promoter was amplified and cloned into the multiple cloning site of the pEGFP-1 vector. The recombinant plasmid pEGFP-Hp was transfected into human umbilical vein endothelial cells (ECV304) and human hepatoma carcinoma (HepG2), laryngocarcinoma (Hep2) and chronic myelogenous leukemia (K562) cell lines. The vectors pEGFP-1 and pEGFP‑N1 were used as negative and positive controls, respectively. The activity and expression of green fluorescent protein (GFP) were analyzed. Results showed that the sequence of the amplified HPSE promoter was in agreement with the GenBank data. The recombinant plasmid pEGFP-Hp was consistent with the expected result. No GFP expression was observed in the transfected cells in the pEGFP-1 group, but a high expression was observed in the pEGFP-N1 group. As regards the pEGFP-Hp group, less fluorescence was revealed in ECV cells with a relatively high fluorescence in tumor cells. The average transfection efficiencies of pEGFP-Hp in the ECV304, HepG2, Hep2 and K562 cell lines were 3.9, 21.3, 10.8 and 6.5%, respectively, while those of pEGFP-Nl were 17.1, 24.0, 14.0 and 11.0%, respectively. The HPSE gene promoter drives the expression of downstream genes in a eukaryotic vector, specifically in tumor cell lines, but its activity is relatively weak.

The sodium iodide symporter (NIS): regulation and approaches to targeting for cancer therapeutics

Expression of the sodium iodide symporter (NIS) is required for efficient iodide uptake in thyroid and lactating breast. Since most differentiated thyroid cancer expresses NIS, β-emitting radioactive iodide is routinely utilized to target remnant thyroid cancer and metastasis after total thyroidectomy. Stimulation of NIS expression by high levels of thyroid-stimulating hormone is necessary to achieve radioiodide uptake into thyroid cancer that is sufficient for therapy. The majority of breast cancer also expresses NIS, but at a low level insufficient for radioiodine therapy. Retinoic acid is a potent NIS inducer in some breast cancer cells. NIS is also modestly expressed in some non-thyroidal tissues, including salivary glands, lacrimal glands and stomach. Selective induction of iodide uptake is required to target tumors with radioiodide. Iodide uptake in mammalian cells is dependent on the level of NIS gene expression, but also successful translocation of NIS to the cell membrane and correct insertion. The regulatory mechanisms of NIS expression and membrane insertion are regulated by signal transduction pathways that differ by tissue. Differential regulation of NIS confers selective induction of functional NIS in thyroid cancer cells, as well as some breast cancer cells, leading to more efficient radioiodide therapy for thyroid cancer and a new strategy for breast cancer therapy. The potential for systemic radioiodide treatment of a range of other cancers, that do not express endogenous NIS, has been demonstrated in models with tumor-selective introduction of exogenous NIS.

Cancer imaging: Gene transcription-based imaging and therapeutic systems

Molecular-genetic imaging of cancer is in its infancy. Over the past decade gene reporter systems have been optimized in preclinical models and some have found their way into the clinic. The search is on to find the best combination of gene delivery vehicle and reporter imaging system that can be translated safely and quickly. The goal is to have a combination that can detect a wide variety of cancers with high sensitivity and specificity in a way that rivals the current clinical standard, positron emission tomography with [(18)F]fluorodeoxyglucose. To do so will require systemic delivery of reporter genes for the detection of micrometastases, and a nontoxic vector, whether viral or based on nanotechnology, to gain widespread acceptance by the oncology community. Merger of molecular-genetic imaging with gene therapy, a strategy that has been employed in the past, will likely be necessary for such imaging to reach widespread clinical use.

Antitumor potential of SLPI promoter controlled recombinant caspase-3 expression in laryngeal carcinoma

The purpose of this study is to develop a specific and efficient targeted gene therapy candidate approach for laryngeal carcinomas. Several promoters of human squamous cell carcinoma antigen 2(SCCA2), secretory leukocyte protease inhibitor (SLPI) and Survivin genes were cloned from human genomic DNA and evaluated for tumor-specific transcription potential in human laryngeal carcinoma Hep-2 cells by dual luciferase assays. One SLPI promoter fragment (677 bp) showed the highest efficiency and specificity, and was used to control the expression of a recombinant active caspases-3 (revCasp3), which could trigger apoptosis without activation of its upstream cascade elements once expressed in a cell, in an adenoviral vector (Ad-SLPI-revCasp3), and its antitumor efficacy was assessed. In vitro infection with Ad-SLPI-revCasp3 showed revCasp3 could be specifically expressed in Hep-2 cells, resulting in efficient activation of endogenous Caspase-3 and subsequent apoptosis of Hep-2 cells. In Hep-2 nude mice xenograft model, intratumoral administration of Ad-SLPI-revCasp3 significantly inhibited tumor growth without obvious loss of body weight and obvious hepatic toxicity. In summary, our study showed the specific and efficient apoptosis-inducing potential of Ad-SLPI-revCasp3, and this makes it a new candidate approach of targeted gene therapy for laryngeal squamous cell carcinoma, which needs further systematic investigation.

Image-guided tumor-selective radioiodine therapy of liver cancer after systemic nonviral delivery of the sodium iodide symporter gene

We reported the induction of tumor-selective iodide uptake and therapeutic efficacy of (131)I in a hepatocellular carcinoma (HCC) xenograft mouse model, using novel polyplexes based on linear polyethylenimine (LPEI), shielded by polyethylene glycol (PEG), and coupled with the epidermal growth factor receptor-specific peptide GE11 (LPEI-PEG-GE11). The aim of the current study in the same HCC model was to evaluate the potential of biodegradable nanoparticle vectors based on pseudodendritic oligoamines (G2-HD-OEI) for systemic sodium iodide symporter (NIS) gene delivery and to compare efficiency and tumor specificity with LPEI-PEG-GE11. Transfection of HCC cells with NIS cDNA, using G2-HD-OEI, resulted in a 44-fold increase in iodide uptake in vitro as compared with a 22-fold increase using LPEI-PEG-GE11. After intravenous application of G2-HD-OEI/NIS HCC tumors accumulated 6-11% ID/g (123)I (percentage of the injected dose per gram tumor tissue) with an effective half-life of 10 hr (tumor-absorbed dose, 281 mGy/MBq) as measured by (123)I scintigraphic gamma camera or single-photon emission computed tomography computed tomography (SPECT CT) imaging, as compared with 6.5-9% ID/g with an effective half-life of only 6 hr (tumor-absorbed dose, 47 mGy/MBq) for LPEI-PEG-GE11. After only two cycles of G2-HD-OEI/NIS/(131)I application, a significant delay in tumor growth was observed with markedly improved survival. A similar degree of therapeutic efficacy had been observed after four cycles of LPEI-PEG-GE11/(131)I. These results clearly demonstrate that biodegradable nanoparticles based on OEI-grafted oligoamines show increased efficiency for systemic NIS gene transfer in an HCC model with similar tumor selectivity as compared with LPEI-PEG-GE11, and therefore represent a promising strategy for NIS-mediated radioiodine therapy of HCC.

Telomerase-driven expression of the sodium iodide symporter (NIS) for in vivo radioiodide treatment of cancer: a new broad-spectrum NIS-mediated antitumor approach

CONTEXT

Telomerase promoters (hTERT and hTR) are useful for transcriptional targeting in gene therapy models of cancer. Telomerase-driven expression of the sodium iodide symporter (NIS) in tumor cells has been successfully used as a reporter gene in vivo using positron emission tomography (PET) imaging.

OBJECTIVE

The aim of this study was to investigate the NIS-mediated therapeutic effect of telomerase promoters in a wide variety of human cancer cell lines.

DESIGN AND METHODS

Promoter fragments from either hTERT or hTR were used to drive the expression of NIS in cell lines derived from melanoma (M14), breast (MDA-MB-231), colon (HT-29), lung (H460), ovarian (OVCAR-3), and thyroid (TPC-1) carcinomas. Iodide uptake assays, protein immunodetection, and clonigenic assays were used to confirm NIS functional expression and the (131)I-mediated cytopathic effect. Tumor xenografts in mice were infected with hTERT and hTR and then treated using radioiodide.

RESULTS

Both promoters were selectively active in cancer cells that were effectively killed by exposure to (131)I. One single dose of 1 mCi (131)I markedly suppressed tumor growth of melanoma-derived tumor xenografts compared with controls. This effect was more modest in colon cancer-derived xenografts in part due to the reduced infectivity and the tumor cystic nature. The therapeutic effect of hTR promoter was found to be stronger than that of hTERT promoter.

CONCLUSIONS

These results demonstrate that telomerase-driven expression of NIS could potentially have applications for (131)I therapy of a wide variety of cancers. Additionally, this is the first study to report NIS-mediated (131)I therapy of melanoma tumors in vivo.

Sodium iodide symporter (NIS)-mediated radionuclide ((131)I, (188)Re) therapy of liver cancer after transcriptionally targeted intratumoral in vivo NIS gene delivery

We reported the therapeutic efficacy of (131)I in hepatocellular carcinoma (HCC) cells stably expressing the sodium iodide symporter (NIS) under the control of the tumor-specific α-fetoprotein (AFP) promoter. In the current study we investigated the efficacy of adenovirus-mediated in vivo NIS gene transfer followed by (131)I and (188)Re administration for the treatment of HCC xenografts. We used a replication-deficient adenovirus carrying the human NIS gene linked to the mouse AFP promoter (Ad5-AFP-NIS) for in vitro and in vivo NIS gene transfer. Functional NIS expression was confirmed by in vivo γ-camera imaging, followed by analysis of NIS protein and mRNA expression. Human HCC (HepG2) cells infected with Ad5-AFP-NIS concentrated 50% of the applied activity of (125)I, which was sufficiently high for a therapeutic effect in an in vitro clonogenic assay. Four days after intratumoral injection of Ad5-AFP-NIS (3×10(9) plaque-forming units) HepG2 xenografts accumulated 14.5% injected dose (ID)/g (123)I with an effective half-life of 13 hr (tumor-absorbed dose, 318 mGy/MBq (131)I). In comparison, 9.2% ID/g (188)Re was accumulated in tumors with an effective half-life of 12.8 hr (tumor-absorbed dose, 545 mGy/MBq). After adenovirus-mediated NIS gene transfer in HepG2 xenografts administration of a therapeutic dose of (131)I or (188)Re (55.5 MBq) resulted in a significant delay in tumor growth and improved survival without a significant difference between (188)Re and (131)I. In conclusion, a therapeutic effect of (131)I and (188)Re was demonstrated in HepG2 xenografts after tumor-specific adenovirus-mediated in vivo NIS gene transfer.

Human sodium iodide symporter added to multidrug resistance 1 small hairpin RNA in a single gene construct enhances the therapeutic effects of radioiodine in a nude mouse model of multidrug resistant colon cancer

The objective of this study was to investigate the therapeutic potential of ¹³¹I added to doxorubicin therapy in multidrug resistance (MDR) mouse colon cancer coexpressing the MDR1 small hairpin RNA (shRNA) and human sodium iodide symporter (hNIS) gene in a single gene construct and to visualize the antitumor effects using molecular nuclear imaging. HCT-15 coexpressing shRNA for MDR1 gene (MDR1 shRNA) and hNIS gene with a single construct was established (referred to as MN61 cell). Inhibition of P-gp function by MDR1 shRNA and functional activity of hNIS gene was assessed using a ⁹⁹(m)Tc sestamibi uptake and ¹²⁵I uptake, respectively. Cytotoxic effects by a combination of doxorubicin and ¹³¹I were determined in parental (HCT-15) or MN61 cells using an in vitro clonogenic assay. Therapeutic effect of either combination therapy (doxorubicin and ¹³¹I) or single therapy (doxorubicin or ¹³¹I alone) was evaluated by tumor volume measurement. ⁹⁹(m)Tc-sestamibi, ¹²³I, and ⁹⁹(m)Tc-pertechnetate images of mice were acquired to evaluate functional assessment in vivo. Cellular uptake of ⁹⁹(m)Tc-sestamibi and ¹²⁵I was approximately 2-fold and 100-fold higher in MN61 cells than in parental cells, respectively. Combination of ¹³¹I and doxorubicin resulted in higher cytotoxcity in MN61 cells as compared with parental cells. Scintigraphic imaging showed higher uptake of ⁹⁹(m)Tc-sestamibi and ¹²³I in MN61 tumor as compared with parental tumor. In mice treated with doxorubicin, there was a slight delay in tumor growth in the MN61 tumor but not in the parental tumor. Cancer treatment with ¹³¹I or doxorubicin induced a rapid reduction of tumor volume in the MN61 tumor but not in the parental tumor. Combination therapy further generated a rapid reduction of tumor volume as compared with ¹³¹I therapy alone (p < 0.05). A combination hNIS mediated radioiodine gene therapy added to MDR1 shRNA treatment improved the effects of cancer treatment in a MDR cancer model and could enable visualization of the antitumor effects with nuclear imaging.

Image-guided, tumor stroma-targeted 131I therapy of hepatocellular cancer after systemic mesenchymal stem cell-mediated NIS gene delivery

Due to its dual role as reporter and therapy gene, the sodium iodide symporter (NIS) allows noninvasive imaging of functional NIS expression by (123)I-scintigraphy or (124)I-PET imaging before the application of a therapeutic dose of (131)I. NIS expression provides a novel mechanism for the evaluation of mesenchymal stem cells (MSCs) as gene delivery vehicles for tumor therapy. In the current study, we stably transfected bone marrow-derived CD34(-) MSCs with NIS cDNA (NIS-MSC), which revealed high levels of functional NIS protein expression. In mixed populations of NIS-MSCs and hepatocellular cancer (HCC) cells, clonogenic assays showed a 55% reduction of HCC cell survival after (131)I application. We then investigated body distribution of NIS-MSCs by (123)I-scintigraphy and (124)I-PET imaging following intravenous (i.v.) injection of NIS-MSCs in a HCC xenograft mouse model demonstrating active MSC recruitment into the tumor stroma which was confirmed by immunohistochemistry and ex vivo γ-counter analysis. Three cycles of systemic MSC-mediated NIS gene delivery followed by (131)I application resulted in a significant delay in tumor growth. Our results demonstrate tumor-specific accumulation and therapeutic efficacy of radioiodine after MSC-mediated NIS gene delivery in HCC tumors, opening the prospect of NIS-mediated radionuclide therapy of metastatic cancer using MSCs as gene delivery vehicles.

Epidermal growth factor receptor-targeted (131)I-therapy of liver cancer following systemic delivery of the sodium iodide symporter gene

We recently demonstrated tumor-selective iodide uptake and therapeutic efficacy of radioiodine in neuroblastoma tumors after systemic nonviral polyplex-mediated sodium iodide symporter (NIS) gene delivery. In the present study, we used novel polyplexes based on linear polyethylenimine (LPEI), polyethylene glycol (PEG), and the synthetic peptide GE11 as an epidermal growth factor receptor (EGFR)-specific ligand to target a NIS-expressing plasmid to hepatocellular carcinoma (HCC) (HuH7). Incubation of HuH7 cells with LPEI-PEG-GE11/NIS polyplexes resulted in a 22-fold increase in iodide uptake, which was confirmed in other cancer cell lines correlating well with EGFR expression levels. Using (123)I-scintigraphy and ex vivo γ-counting, HuH7 xenografts accumulated 6.5-9% injected dose per gram (ID/g) (123)I, resulting in a tumor-absorbed dose of 47 mGray/Megabecquerel (mGy/MBq) (131)Iodide ((131)I) after intravenous (i.v.) application of LPEI-PEG-GE11/NIS. No iodide uptake was observed in other tissues. After pretreatment with the EGFR-specific antibody cetuximab, tumoral iodide uptake was markedly reduced confirming the specificity of EGFR-targeted polyplexes. After three or four cycles of polyplex/(131)I application, a significant delay in tumor growth was observed associated with prolonged survival. These results demonstrate that systemic NIS gene transfer using polyplexes coupled with an EGFR-targeting ligand is capable of inducing tumor-specific iodide uptake, which represents a promising innovative strategy for systemic NIS gene therapy in metastatic cancers.

Sodium butyrate enhances the expression of baculovirus-mediated sodium/iodide symporter gene in A549 lung adenocarcinoma cells

OBJECTIVE

Increased expression of sodium/iodide symporter (NIS) is required for reporter gene imaging and effective radioiodine treatment of tumor. We investigated whether increased accumulation of iodine can be induced by sodium butyrate through a newly developed baculoviral transfer of the human NIS (hNIS) gene in A549 human lung adenocarcinoma.

METHODS

A recombinant baculovirus [Bac-cytomegalovirus (CMV)-hNIS] encoding hNIS gene under the control of the CMV promoter was constructed. After A549 cells were transfected with Bac-CMV-hNIS in the presence of sodium butyrate, the expression of hNIS protein was detected by immunofluorescence and western blot analysis. The uptake and efflux of iodine were determined after the incubation of the transfected cells with I-iodide in the presence or absence of sodium butyrate.

RESULTS

Immunocytochemical staining and western blot analysis showed increased hNIS protein expression in A549 cells transfected with Bac-CMV-hNIS after sodium butyrate treatment. Bac-CMV-hNIS transfected A549 cells accumulated up to about nine times more I than nontransfected cells; the amount of I uptake increased in a sodium butyrate in dose-dependent manner (P<0.001). However, rapid efflux of radioactivity was observed, with 50% lost during the first 2 min after I-containing medium had been replaced by a nonradioactive medium.

CONCLUSION

Our results indicated that an improved efficiency of baculovirus-mediated hNIS reporter gene imaging in lung adenocarcinoma is possible with treatment with sodium butyrate. However, additional conditions need to be defined to reduce the rapid efflux of radioiodine for the purpose of radionuclide therapy.

Targeting of tumor radioiodine therapy by expression of the sodium iodide symporter under control of the survivin promoter

To test the feasibility of using the survivin promoter to induce specific expression of sodium/iodide symporter (NIS) in cancer cell lines and tumors for targeted use of radionuclide therapy, a recombinant adenovirus, Ad-SUR-NIS, that expressed the NIS gene under control of the survivin promoter was constructed. Ad-SUR-NIS mediating iodide uptake and cytotoxicity was performed in vitro. Scintigraphic, biodistribution and radioiodine therapy studies were performed in vivo. PC-3 (prostate); HepG2 (hepatoma) and A375 (melanoma) cancer cells all exhibited perchlorate-sensitive iodide uptake after infection with Ad-SUR-NIS, ∼50 times higher than that of negative control Ad-CMV-GFP-infected cells. No significant iodide uptake was observed in normal human dental pulp fibroblast (DPF) cells after infection with Ad-SUR-NIS. Clonogenic assays demonstrated that Ad-SUR-NIS-infected cancer cells were selectively killed by exposure to ¹³¹I. Ad-SUR-NIS-infected tumors show significant radioiodine accumulation (13.3±2.85% ID per g at 2 h post-injection), and the effective half-life was 3.1 h. Moreover, infection with Ad-SUR-NIS in combination with ¹³¹I suppressed tumor growth. These results indicate that expression of NIS under control of the survivin promoter can likely be used to achieve cancer-specific expression of NIS in many types of cancers. In combination with radioiodine therapy, this strategy is a possible method of cancer gene therapy.

The biology of the sodium iodide symporter and its potential for targeted gene delivery

The sodium iodide symporter (NIS) is responsible for thyroidal, salivary, gastric, intestinal and mammary iodide uptake. It was first cloned from the rat in 1996 and shortly thereafter from human and mouse tissue. In the intervening years, we have learned a great deal about the biology of NIS. Detailed knowledge of its genomic structure, transcriptional and post-transcriptional regulation and pharmacological modulation has underpinned the selection of NIS as an exciting approach for targeted gene delivery. A number of in vitro and in vivo studies have demonstrated the potential of using NIS gene therapy as a means of delivering highly conformal radiation doses selectively to tumours. This strategy is particularly attractive because it can be used with both diagnostic (99mTc, 125I, 124I)) and therapeutic (131I, 186Re, 188Re, 211At) radioisotopes and it lends itself to incorporation with standard treatment modalities, such as radiotherapy or chemoradiotherapy. In this article, we review the biology of NIS and discuss its development for gene therapy.

Genetics and phenomics of hypothyroidism and goiter due to NIS mutations

Molecular cloning of the NIS gene in 1996 allowed examination of the molecular basis of congenital hypothyroidism due to iodide transport defect (ITD) many years after the first case was described by Federman et al. in 1958. Since 1997, when the first NIS mutation causing ITD was identified and characterized, 12 different NIS molecular defects have been described in 31 ITD patients. Interestingly, marked clinical heterogeneity between patients with the same NIS mutation and in patients with different mutations in the NIS gene without a clear genotype-phenotype correlation has been observed. The study of NIS mutations as the molecular basis of ITD has not only yielded extremely valuable structure/function information on NIS, but has also provided an important tool for preclinical diagnosis and genetic counseling of ITD patients.

Therapeutic effect of sodium iodide symporter gene therapy combined with external beam radiotherapy and targeted drugs that inhibit DNA repair

Adenoviral (AdV) transfer of sodium iodide symporter (NIS) gene has translational potential, but relatively low levels of transduction and subsequent radioisotope uptake limit the efficacy of the approach. In previous studies, we showed that combining NIS gene delivery with external beam radiotherapy (EBRT) and DNA damage repair inhibitors increased viral gene expression and radioiodide uptake. Here, we report the therapeutic efficacy of this strategy. An adenovirus expressing NIS from a telomerase promoter (Ad-hTR-NIS) was cytotoxic combined with relatively high-dose (50 microCi) (131)I therapy and enhanced the efficacy of EBRT combined with low-dose (10 and 25 microCi) (131)I therapy in colorectal and head and neck cancer cells. Combining this approach with ataxia-telangiectasia mutated (ATM) or DNA-dependent protein kinase (DNA-PK) inhibition caused maintenance of double-stranded DNA breaks (DSBs) at 24 hours and increased cytotoxicity on clonogenic assay. When the triplet of NIS-mediated (131)I therapy, EBRT, and DNA-PKi was used in vivo, 90% of mice were tumor-free at 5 weeks. Acute radiation toxicity in the EBRT field was not exacerbated. In contrast, DNA-PKi did not enhance the therapeutic efficacy of EBRT plus adenovirus-mediated HSVtk/ganciclovir (GCV). Therefore, combining NIS gene therapy and EBRT represents an ideal strategy to exploit the therapeutic benefits of novel radiosensitizers.

Sodium iodide symporter and the radioiodine treatment of thyroid carcinoma

Since the specific accumulation of iodide in thyroid was found in 1915, radioiodine has been widely applied to diagnose and treat thyroid cancer. Iodide uptake occurs across the membrane of the thyroid follicular cells and cancer cells through an active transporter process mediated by the sodium iodide symporter (NIS). The NIS coding genes were cloned and identified from rat and human in 1996. Evaluation of the NIS gene and protein expression is critical in the management of thyroid cancer, and several approaches have been tried to increase NIS levels. Identification of the NIS gene has provided a means of expanding its role in the radionuclide gene therapy of nonthyroidal cancers as well as thyroid cancer. In this article, we explain the relationship between NIS expression and the treatment of thyroid carcinoma with I-131, and we include a review of the results of our experimental and clinical trials.

Enhanced anti-tumor effects of combined MDR1 RNA interference and human sodium/iodide symporter (NIS) radioiodine gene therapy using an adenoviral system in a colon cancer model

Using an adenoviral system as a delivery mediator of therapeutic gene, we investigated the therapeutic effects of the use of combined MDR1 shRNA and human NIS (hNIS) radioiodine gene therapy in a mouse colon xenograft model. In vitro uptake of Tc-99m sestamibi was increased approximately two-fold in cells infected with an adenovirus vector that expressed MDR1 shRNA (Ad-shMDR1) and I-125 uptake was 25-fold higher in cells infected with an adenovirus vector that expressed human NIS (Ad-hNIS) as compared with control cells. As compared with doxorubicin or I-131 treatment alone, the combination of doxorubicin and I-131 resulted in enhanced cytotoxicity for both Ad-shMDR1- and Ad-hNIS-infected cells, but not for control cells. In vivo uptake of Tc-99m sestamibi and Tc-99m pertechnetate was twofold and 10-fold higher for Ad-shMDR1 and Ad-hNIS-infected tumors as compared with tumors infected with a control adenovirus construct that expressed β-galactrosidase (Ad-LacZ), respectively. In mice treated with either doxorubicin or I-131 alone, there was a slight delay in tumor growth as compared to mice treated with Ad-LacZ. However, combination therapy with doxorubicin and I-131 induced further significant inhibition of tumor growth as compared with mice treated with Ad-LacZ. We have shown successful therapeutic efficacy of combined MDR shRNA and hNIS radioiodine gene therapy using an adenoviral vector system in a mouse colon cancer model. Adenovirus-mediated cancer gene therapy using MDR1 shRNA and hNIS would be a useful tool for the treatment of cancer cells expressing multi-drug resistant genes.

Targeted RNA interference for hepatic fibrosis

Hepatic fibrosis is a common consequence in patients with chronic liver damage. To date, no agent has been approved for the treatment of hepatic fibrosis. RNA interference (RNAi) is known to be a powerful tool for post-transcriptional gene silencing and has opened new avenues in gene therapy. The problems of lack of cell specificity in vivo and subsequently the occurrence of side effects has hampered the development of hepatic fibrosis treatment. To overcome these shortcomings, several targeted strategies have been developed, such as hydrodynamics-based approaches, local administration, cell-type-selective ligands and cell-type-specific promoters or enhancers, etc. Here, we provide an overview of targeted strategies for the treatment of hepatic fibrosis, and particularly, targeted RNAi for hepatic fibrosis.

Targeted radioiodine therapy of neuroblastoma tumors following systemic nonviral delivery of the sodium iodide symporter gene

PURPOSE

We recently reported the significant therapeutic efficacy of radioiodine therapy in various tumor mouse models following transcriptionally targeted sodium iodide symporter (NIS) gene transfer. These studies showed the high potential of NIS as a novel diagnostic and therapeutic gene for the treatment of extrathyroidal tumors. As a next crucial step towards clinical application of NIS-mediated radionuclide therapy we aim at systemic delivery of the NIS gene to target extrathyroidal tumors even in the metastatic stage.

EXPERIMENTAL DESIGN

In the current study, we used synthetic polymeric vectors based on pseudodendritic oligoamines with high intrinsic tumor affinity (G2-HD-OEI) to target a NIS-expressing plasmid (CMV-NIS-pcDNA3) to neuroblastoma (Neuro2A) cells.

RESULTS

Incubation with NIS-containing polyplexes (G2-HD-OEI/NIS) resulted in a 51-fold increase in perchlorate-sensitive iodide uptake activity in Neuro2A cells in vitro. Through (123)I-scintigraphy and ex vivo gamma counting Neuro2A tumors in syngeneic A/J mice were shown to accumulate 8% to 13% ID/g (123)I with a biological half-life of 13 hours, resulting in a tumor-absorbed dose of 247 mGy/MBq (131)I after i.v. application of G2-HD-OEI/NIS. Nontarget organs, including liver, lung, kidneys, and spleen revealed no significant iodide uptake. Moreover, two cycles of systemic NIS gene transfer followed by (131)I application (55.5 MBq) resulted in a significant delay in tumor growth associated with markedly improved survival.

CONCLUSIONS

In conclusion, our data clearly show the high potential of novel pseudodendritic polymers for tumor-specific NIS gene delivery after systemic application, opening the prospect of targeted NIS-mediated radionuclide therapy of nonthyroidal tumors even in metastatic disease.

Biotinylated disulfide containing PEI/avidin bioconjugate shows specific enhanced transfection efficiency in HepG2 cells

Targeting of non-viral gene vectors to liver cells could offer the opportunity to cure liver diseases. In this paper, disulfide-containing polyethylenimine (PEI-SS) was synthesized from low molecular weight branched PEI and cystamine bisacrylamide (CBA), and then grafted with biotin. The obtained biotinylated PEI-SS was bioconjugated with avidin via the biotin-avidin interaction to form a novel gene vector, biotinylated PEI-SS/avidin bioconjugate (ABP-SS). Characteristics of ABP-SS and its pDNA complexes were evaluated in terms of acid-base titration, agarose gel electrophoresis, SEM morphology observation, particle size and zeta-potential measurements, and PEI-SS was used as the control. The acid-base titration results showed that ABP-SS exhibited comparable buffer capability to 25 kDa PEI. The results of gel electrophoresis indicated that ABP-SS was able to condense pDNA efficiently at an N/P ratio of 6 and could be degraded by reducing agent DTT. The ABP-SS/pDNA complexes had a mean particle size of 226 +/- 40 nm and surface charges of 25 mV. The SEM images showed that the complexes had compact structures with spherical or quadrate shapes. In vitro cell viability and transfection of ABP-SS and PEI-SS were compared in HepG2, 293T and H446 cells. Among the three different cell lines, compared with PEI-SS, ABP-SS exhibited much lower cytotoxicity and higher transfection efficacy in HepG2 cells due to the biocompatibility of avidin and the specific interactions between avidin and HepG2 cells. Molecular probes were used to reveal the cellular uptake of complexes, and the results demonstrated that ABP-SS contributes to more cellular uptake of complexes in HepG2 cells, which was consistent with the transfection results.

Effects of theophylline on radioiodide uptake in MCF-7 breast cancer and NIS gene-transduced SNU-C5 colon cancer cells

BACKGROUND

We investigated whether theophylline has the potential to increase radioiodide uptake in nonthyroidal cancer cells.

MATERIALS AND METHODS

MCF-7 cells that express endogenous sodium/iodide symporter (NIS) and SNU-C5 cells adenovirally transduced with the human NIS gene (SNU-C5/NIS) were treated with 10(-7)-2x10(-4) mol/L theophylline for 24 hours before incubation with (125)I, and then, radioiodide uptake and retention were measured. NIS expression was assessed by immunohistochemistry and Western blot analysis, using an antihuman NIS monoclonal antibody.

RESULTS

Theophylline at 10(-6)-2x10(-4) mol/L significantly and dose dependently augmented radioiodide uptake in MCF-7 cells and at 10(-6)-10(-5) mol/L in SNU-C5/NIS cells, without affecting radioiodide efflux. Abrogation by KClO(4)(-) demonstrated that the effect of theophylline occurred through specific iodide transport. Immunohistochemistry revealed dose-dependent increases of NIS staining in MCF-7 and SNU-C5/NIS cells by 10(-6)-10(-4) and 10(-6)-10(-5) mol/L theophylline, respectively. Western blot analysis demonstrated similar findings, showing increased expression of NIS on the membrane of SNU-C5/NIS and MCF-7 cells by theophylline treatment.

CONCLUSIONS

Theophylline can augment radioiodide uptake in breast cancer cells and NIS gene-transduced cancer cells through the upregulation of NIS expression. Therefore, further investigations are warranted to explore the potential utility of this phenomenon for enhancing radioiodide-based imaging and therapies of NIS gene-transduced cancer cells.