Radioiodine therapy of colon cancer following tissue-specific sodium iodide symporter gene transfer

Survivin-Sodium Iodide Symporter Reporter as a Non-Invasive Diagnostic Marker to Differentiate Uterine Leiomyosarcoma from Leiomyoma

Leiomyosarcoma (LMS) has been challenging to diagnose because of limitations in clinical and radiographic predictors, as well as the lack of reliable serum or urinary biomarkers. Most uterine masses consist of benign leiomyoma (LM). However, it is currently a significant challenge in gynecology practice to differentiate LMS from LM. This inability poses grave consequences for patients, leading to a high number of unnecessary hysterectomies, infertility, and other major morbidities and possible mortalities. This study aimed to evaluate the use of Survivin-Sodium iodide symporter (Ad-Sur-NIS) as a reporter gene biomarker to differentiate malignant LMS from benign LM by using an F18-NaBF4 PET/CT scan. The PET/CT scan images showed a significantly increased radiotracer uptake and a decreased radiotracer decay attributable to the higher abundance of Ad-Sur-NIS in the LMS tumors compared to LM (p < 0.05). An excellent safety profile was observed, with no pathological or metabolic differences detected in Ad-Sur-NIS-treated animal versus the vehicle control. Ad-Sur-NIS as a PET scan reporter is a promising imaging biomarker that can differentiate uterine LMS from LM using F18-NaBF4 as a radiotracer. As a new diagnostic method, the F18 NaBF4 PET/CT scan can provide a much-needed tool in clinical practices to effectively triage women with suspicious uterine masses and avoid unnecessary invasive interventions.

The Thyroid Na+/I- Symporter: Molecular Characterization and Genomic Regulation

Iodide (I-) is an essential constituent of the thyroid hormones triiodothyronine (T₃) and thyroxine (T₄), and the iodide concentrating mechanism of the thyroid gland is essential for the synthesis of these hormones. In addition, differential uptake of iodine isotopes (radioiodine) is a key modality for the diagnosis and therapy of thyroid cancer. The sodium dependent iodide transport activity of the thyroid gland is mainly attributed to the functional expression of the Na+/I- Symporter (NIS) localized at the basolateral membrane of thyrocytes. In this paper, we review and summarize current data on molecular characterization, on structure and function of NIS protein, as well as on the transcriptional regulation of NIS encoding gene in the thyroid gland. We also propose that a better and more precise understanding of NIS gene regulation at the molecular level in both healthy and malignant thyroid cells may lead to the identification of small molecule candidates. These could then be translated into clinical practice for better induction and more effective modulation of radioiodine uptake in dedifferentiated thyroid cancer cells and in their distant metastatic lesions.

Effect of sodium/iodide symporter (NIS)-mediated radioiodine therapy on estrogen receptor-negative breast cancer

Since the sodium/iodide symporter (NIS) stimulates the iodine uptake in normal lactating breast, our study aimed to study the effect of NIS-mediated radioiodide therapy on ER-negative breast cancers. A recombinant lentivirus plasmid encoding the human NIS (hNIS) gene and firefly luciferase (Fluc) was constructed. MDA-MB-231 cells were transfected with the recombinant lentivirus, and the hNIS gene expression was identified by western blot analysis and real-time PCR. Tissue-specific expression of the NIS gene was confirmed by immunohistochemical (IHC) staining. Functional NIS activity in the MDA-hNIS cells was confirmed by the uptake of 131I and cytotoxicity assays. The relative expression level of hNIS mRNA exhibited a 10-fold higher expression in the MDA-hNIS cells compared with the level in the control cells without the endogenous NIS gene. Abundant expression of hNIS protein was noted in the cell membrane compared to the cytoplasm which confirmed the efficient expression of the functional hNIS gene. Iodine uptake into the MDA-hNIS cells was rapid, reaching a maximum after 15 min, followed by a decline. Exposure of the MDA-hNIS cells with 131I resulted in a time-dependent reduction in colony formation compared with the survival of the control (MDA) cells. Our results confirmed that NIS overexpression enhances the sensitivity of ER-negative breast cancer cells to radioiodide therapy.

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.

Baculovirus vector-mediated transfer of sodium iodide symporter and plasminogen kringle 5 genes for tumor radioiodide therapy

Background

Both tumor cells and their supporting endothelial cells should be considered for targeted cell killing when designing cancer treatments. Here we investigated the feasibility of combining radioiodide and antiangiogenic therapies after baculovirus-mediated transfer of genes encoding the sodium iodide symporter (NIS) and plasminogen kringle 5 (K5).

Methods

A recombinant baculovirus containing the NIS gene under control of the human telomerase reverse transcriptase (hTERT) promoter and the K5 gene driven by the early growth response 1 (Egr1) promoter was developed. Dual-luciferase reporter assay was performed to confirm the activation of hTERT transcription. NIS and K5 gene expression were identified by Western blot and Real-Time PCR. Functional NIS activity in baculovirus-infected Hela cells was confirmed by the uptake of ¹²⁵I and cytotoxicity of ¹³¹I. The apoptotic effect of ¹³¹I-induced K5 on baculovirus-infected human umbilical vein endothelial cells (HUVECs) was analyzed by a flow cytometry-based assay. In vivo, NIS reporter gene imaging and therapeutic experiments with ¹³¹I were performed. Finally, the microvessel density (MVD) in tumors after treatment was determined by CD31 immunostaining.

Results

The activation of hTERT transcription was specifically up-regulated in tumor cells. NIS gene expression markedly increased in baculovirus-infected HeLa cells, but not in MRC5 cells. The Hela cells showed a significant increase of ¹²⁵I uptake, which was inhibited by NaClO₄, and a notably decreased cell survival rate by ¹³¹I treatment. Expression of the K5 gene induced by ¹³¹I was elevated in a dose- and time-dependent manner and resulted in the apoptosis of HUVECs. Furthermore, ¹³¹I SPECT imaging clearly showed cervical tumor xenografts infected with recombinant baculovirus. Following therapy, tumor growth was significantly retarded. CD31 immunostaining confirmed a significant decrease of MVD.

Conclusion

The recombinant baculovirus supports a promising strategy of NIS-based raidoiodide therapy combined with K5-based antiangiogenic therapy by targeting both the tumor and its supporting vessels.

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.

A novel oncolytic viral therapy and imaging technique for gastric cancer using a genetically engineered vaccinia virus carrying the human sodium iodide symporter

Background

Gastric cancers have poor overall survival despite recent advancements in early detection methods, endoscopic resection techniques, and chemotherapy treatments. Vaccinia viral therapy has had promising therapeutic potential for various cancers and has a great safety profile. We investigated the therapeutic efficacy of a novel genetically-engineered vaccinia virus carrying the human sodium iodide symporter (hNIS) gene, GLV-1 h153, on gastric cancers and its potential utility for imaging with ^99mTc pertechnetate scintigraphy and ¹²⁴I positron emission tomography (PET).

Methods

GLV-1 h153 was tested against five human gastric cancer cell lines using cytotoxicity and standard viral plaque assays. In vivo, subcutaneous flank tumors were generated in nude mice with human gastric cancer cells, MKN-74. Tumors were subsequently injected with either GLV-1 h153 or PBS and followed for tumor growth. ^99mTc pertechnetate scintigraphy and ¹²⁴I microPET imaging were performed.

Results

GFP expression, a surrogate for viral infectivity, confirmed viral infection by 24 hours. At a multiplicity of infection (MOI) of 1, GLV-1 h153 achieved > 90% cytotoxicity in MNK-74, OCUM-2MD3, and AGS over 9 days, and >70% cytotoxicity in MNK- 45 and TMK-1. In vivo, GLV-1 h153 was effective in treating xenografts (p < 0.001) after 2 weeks of treatment. GLV-1 h153-infected tumors were readily imaged by ^99mTc pertechnetate scintigraphy and ¹²⁴I microPET imaging 2 days after treatment.

Conclusions

GLV-1 h153 is an effective oncolytic virus expressing the hNIS protein that can efficiently regress gastric tumors and allow deep-tissue imaging. These data encourages its continued investigation in clinical settings.

American Thyroid Association Guide to investigating thyroid hormone economy and action in rodent and cell models

BACKGROUND

An in-depth understanding of the fundamental principles that regulate thyroid hormone homeostasis is critical for the development of new diagnostic and treatment approaches for patients with thyroid disease.

SUMMARY

Important clinical practices in use today for the treatment of patients with hypothyroidism, hyperthyroidism, or thyroid cancer are the result of laboratory discoveries made by scientists investigating the most basic aspects of thyroid structure and molecular biology. In this document, a panel of experts commissioned by the American Thyroid Association makes a series of recommendations related to the study of thyroid hormone economy and action. These recommendations are intended to promote standardization of study design, which should in turn increase the comparability and reproducibility of experimental findings.

CONCLUSIONS

It is expected that adherence to these recommendations by investigators in the field will facilitate progress towards a better understanding of the thyroid gland and thyroid hormone dependent processes.

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.

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 glial fibrillary acidic protein promoter directs sodium/iodide symporter gene expression for radioiodine therapy of malignant glioma

Radioiodine is a routine therapy for differentiated thyroid cancers. Non-thyroid cancers may be treated with radio-iodine following transfection with the human sodium/iodide symporter (hNIS) gene. The glial fibrillary acidic protein (GFAP) promoter is an effective tumor-specific promoter for gene expression and thus may be useful in targeted gene therapy of malignant glioma. The present study used GFAP promoter-modulated expression of the hNIS gene in an experimental model of radioiodine-based treatment for malignant glioma. Cells were transfected using a recombination adeno-virus and evaluated in cells by studying the transfected transgene expression through western blot analysis, (125)I uptake and efflux, clonogenicity following (131)I treatment and radioiodine therapy using a U87 xenograft nude mouse model. Following transfection with the hNIS gene, the cells showed 95-70-fold higher (125)I uptake compared with the control cells transfected with Ad-cytomegalovirus (CMV)-enhanced green fluorescent protein (EGFP). The western blotting revealed bands of ∼70, 49 and 43 kDa, consistent with the hNIS, GFAP and β-actin proteins. The clonogenic assay indicated that, following exposure to 500 μCi of (131)I-iodide for 12 h, >90% of cells transfected with the hNIS gene were killed. Ad-GFAP-hNIS-transfected and 2 mCi (131)I-injected U87 xenograft nude mice survived the longest of the three groups. The hNIS-expressing tumor tissue accumulated (99m)TcO(4) rapidly within 30 min of it being intraperitoneally injected. The experiments demonstrated that effective (131)I therapy was achieved in the malignant glioma cell lines following the induction of tumor-specific iodide uptake activity by GFAP promoter-directed hNIS gene expression in vitro and in vivo. (131)I therapy retarded Ad-GFAP-hNIS transfected-tumor growth following injection with (131)I in U87 xenograft-bearing nude mice.

Progress in gene therapy for prostate cancer

Gene therapy has held promise to correct various disease processes. Prostate cancer represents the second leading cause of cancer death in American men. A number of clinical trials involving gene therapy for the treatment of prostate cancer have been reported. The ability to efficiently transduce tumors with effective levels of therapeutic genes has been identified as a fundamental barrier to effective cancer gene therapy. The approach utilizing gene therapy in prostate cancer patients at our institution attempts to address this deficiency. The sodium-iodide symporter (NIS) is responsible for the ability of the thyroid gland to transport and concentrate iodide. The characteristics of the NIS gene suggest that it could represent an ideal therapeutic gene for cancer therapy. Published results from Mayo Clinic researchers have indicated several important successes with the use of the NIS gene and prostate gene therapy. Studies have demonstrated that transfer of the human NIS gene into prostate cancer using adenovirus vectors in vitro and in vivo results in efficient uptake of radioactive iodine and significant tumor growth delay with prolongation of survival. Preclinical successes have culminated in the opening of a phase I trial for patients with advanced prostate disease which is currently accruing patients. Further study will reveal the clinical promise of NIS gene therapy in the treatment of prostate as well as other malignancies.

A steep radioiodine dose response scalable to humans in sodium-iodide symporter (NIS)-mediated radiovirotherapy for prostate cancer

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. We have extended the use of NIS-mediated radioiodine therapy to prostate cancer. We have developed a prostate tumor specific conditionally replicating adenovirus (CRAd) that expresses hNIS (Ad5PB_RSV-NIS). For radiovirotherapy to be effective in humans, the radioiodine dose administered in the pre-clinical animal model should scale to the range of acceptable doses in humans. We performed ¹³¹I dose-response experiments aiming to determine the dose required in mice to achieve efficient radiovirotherapy. Efficacy was determined by measuring tumor growth and survival times. We observed that individual tumors display disparate growth rates which preclude averaging within a treatment modality indicating heterogeneity of growth rate. We further show that a statistic and stochastic approach must be used when comparing the effect of an anti-cancer therapy on a cohort of tumors. Radiovirotherapy improves therapeutic value over virotherapy alone by slowing the rate of tumor growth in a more substantial manner leading to an increase in survival time. We also show that the radioiodine doses needed to achieve this increase scaled well within the current doses used for treatment of thyroid cancer in humans.

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.

Viral dose, radioiodide uptake, and delayed efflux in adenovirus-mediated NIS radiovirotherapy correlates with treatment efficacy

We have constructed a prostate tumor-specific conditionally replicating adenovirus (CRAd), named Ad5PB_RSV-NIS, which expresses the human sodium iodine symporter (NIS) gene. LNCaP tumors were established in nude mice and infected with this CRAd to study tumor viral spread, NIS expression, and efficacy. Using quantitative PCR, we found a linear correlation between the viral dose and viral genome copy numbers recovered after tumor infection. Confocal microscopy showed a linear correlation between adenovirus density and NIS expression. Radioiodide uptake vs virus dose-response curves revealed that the dose response curve was not linear and displayed a lower threshold of detection at 10(7) vp (virus particles) and an upper plateau of uptake at 10(11) vp. The outcome of radiovirotherapy was highly dependent upon viral dose. At 10(10) vp, no significant differences were observed between virotherapy alone or radiovirotherapy. However, when radioiodide therapy was combined with virotherapy at a dose of 10(11) vp, significant improvement in survival was observed, indicating a relationship between viral dose-response uptake and the efficacy of radiovirotherapy. The reasons behind the differences in radioiodide therapy efficacy can be ascribed to more efficient viral tumor spread and a decrease in the rate of radioisotope efflux. Our results have important implications regarding the desirable and undesirable characteristics of vectors for clinical translation of virus-mediated NIS transfer therapy.

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.

Stimulation of cultured h9 human embryonic stem cells with thyroid stimulating hormone does not lead to formation of thyroid-like cells

The sodium-iodine symporter (NIS) is expressed on the cell membrane of many thyroid cancer cells, and is responsible for the radioactive iodine accumulation. However, treatment of anaplastic thyroid cancer is ineffective due to the low expression of NIS on cell membranes of these tumor cells. Human embryonic stem cells (ESCs) provide a potential vehicle to study the mechanisms of NIS expression regulation during differentiation. Human ESCs were maintained on feeder-independent culture conditions. RT-qPCR and immunocytochemistry were used to study differentiation marker expression, ¹²⁵I uptake to study NIS function. We designed a two-step protocol for human ESC differentiation into thyroid-like cells, as was previously done for mouse embryonic stem cells. First, we obtained definitive endoderm from human ESCs. Second, we directed differentiation of definitive endoderm cells into thyroid-like cells using various factors, with thyroid stimulating hormone (TSH) as the main differentiating factor. Expression of pluripotency, endoderm and thyroid markers and ¹²⁵I uptake were monitored throughout the differentiation steps. These approaches did not result in efficient induction of thyroid-like cells. We conclude that differentiation of human ESCs into thyroid cells cannot be induced by TSH media supplementation alone and most likely involves complicated developmental patterns that are yet to be understood.

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.

Enhanced antiproliferative effects of combination hexokinase II shRNA and NIS gene therapy on vascular smooth muscle cells

INTRODUCTION

This study was designed to determine the antiproliferative effects of combination gene therapy using sodium iodide symporter (NIS)-based radioiodine and lentivirus-mediated short hairpin RNA (shRNA) against hexokinase II (HKII) on vascular smooth muscle cells (VSMCs).

METHODS

A7r5 rat VSMCs were stably transfected with a dual-expression vector of NIS and Fluc (A7r5-NL cells). Functional assessment was performed by radioiodine uptake assay, luciferase assay and confocal microscopy. After exposure to lentivirus-HKII-shRNA, the (18)F-FDG uptake test and HK activity assay were performed. The effects of combination therapy with (131)I and lentivirus-HKII-shRNA on VSMCs were assessed with an in vitro clonogenic assay. In vivo bioluminescence and nuclear imaging were undertaken using a xenografted mouse model.

RESULTS

In vitro functional assessment confirmed expression of NIS and Fluc genes in A7r5-NL, but not in parent A7r5 cells. Transfection of lentivirus-HKII-shRNA resulted in a significant decrease in messenger RNA expression of the HKII gene, (18)F-FDG uptake and HK activity. The cell survival rate of A7r5-NL decreased to 61.9% and 90.5% by single therapy with 7.4 MBq of (131)I or lentivirus-HKII-shRNA, respectively, and further decreased to 42.9% by combined therapy (P<.05). In vivo bioluminescent and gamma camera images clearly demonstrated optical signals and (99m)Tc pertechnetate uptake at the site of A7r5-NL cell inoculation in nude mice.

CONCLUSION

The enhanced antiproliferative effect on VSMCs was achieved by a combination of NIS-based radioiodine and lentivirus-mediated HKII shRNA gene therapy. Successful demonstration of in vivo dual reporter gene imaging assures the potential for further application in an animal model.

Cotransfected sodium iodide symporter and human tyroperoxidase genes following human telomerase reverse transcriptase promoter for targeted radioiodine therapy of malignant glioma cells

INTRODUCTION

Radioiodine is a routine therapy for differentiated thyroid cancers. In principle, undifferentiated thyroid cancers as well as nonthyroid cancers can concentrate and, thus, be treated with radioiodine after transfection with the human sodium iodide symporter (hNIS) gene. The human telomerase reverse transcriptase (hTERT) promoter is an effective tumor-specific promoter of gene expression and, thus, may be useful in targeted gene therapy of cancer.

METHODS

We used hTERT promoter-modulated expression of the hNIS and human thyroperoxidase (hTPO) genes in an experimental model of radioiodine-based treatment of malignant glioma. Cells were cotransfected by adenovirus in which the hNIS gene had been coupled to the hTERT promoter and the hTPO gene had been coupled to the human cytomegalovirus (CMV) promoter (Ad-hTERT-hNIS and Ad-CMV-hTPO, respectively), and they were evaluated in cells thus transfecting transgene expression by western blots, (125)I uptake and influx, and clonogenecity after (131)I treatment.

RESULTS

After cotransfection with two adenovirus, cells showed about 31-34 times higher (125)I uptake than the control cells transfected with Ad-CMV-EGFP (enhanced green fluorescent protein) and almost 1.3-1.4 times higher (125)I uptake than cells only transfected with Ad-hTERT-hNIS. Western blots revealed two bands of ∼70 and 110 kDa, respectively. The in vitro clonogenic assay indicated that, after exposure to 100-1000 μCi of (131)I-iodide for 12 hours, 91%-94% of cells cotransfected with the hNIS and hTPO genes, 88%-93% of cells transfected with the hNIS gene, and only 62%-68% of control (nontransfected) cells were killed.

CONCLUSIONS

The experiments demonstrated that an effective therapy of (131)I was achieved in malignant glioma cell lines after induction of tumor-specific iodide uptake activity by the hTERT promoter-directed NIS expression in vitro. Cotransfection of the hNIS and hTPO genes can lead to longer retention of radioiodide, but did not increase cell killing over that achieved with transfection with the hNIS gene alone.

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.

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.

Evaluation of [18F]-tetrafluoroborate as a potential PET imaging agent for the human sodium/iodide symporter in a new colon carcinoma cell line, HCT116, expressing hNIS

PURPOSE

Accumulation of iodide and other substrates via the human sodium/iodide symporter (hNIS) is fundamental to imaging and therapy of thyroid disease, hNIS reporter gene imaging and hNIS-mediated gene therapy. There is no readily available positron emission tomography (PET) tracer for hNIS. Our aim was to develop a colon carcinoma cell line stably expressing hNIS, and use it to evaluate a novel hNIS PET tracer, [18F]-tetrafluoroborate.

METHODS

Colon carcinoma cell line, HCT116, was stably transfected with hNIS, thus producing a cell line, HCT116-C19, with high hNIS expression. A Fisher rat thyroid cell line, FRTL5, which expresses rat sodium/iodide symporter when stimulated with thyroid-stimulating hormone, was used for comparison. Accumulation of [188Re]-perrhenate, [99mTc]-pertechnetate and [18F]-tetrafluoroborate was evaluated with and without perchlorate inhibition using an automated radioimmune assay system, LigandTracer. The affinity of [18F]-tetrafluoroborate for hNIS, and its half-maximal inhibitory concentration (IC50) for the inhibition of [99mTc]-pertechnetate transport were determined from the plateau accumulation of [18F]-tetrafluoroborate and [99mTc]-pertechnetate, respectively, as a function of tetrafluoroborate concentration.

RESULTS

[18F]-tetrafluoroborate accumulated effectively in both FRTL5 and HCT116-C19 cells. The accumulation in HCT116-C19 cells (plateau accumulation 31%) was comparable to that of [188Re]-perrhenate (41%) and [99mTc]-pertechnetate (46%). Its affinity for hNIS and half-maximal inhibitory concentration (IC50) for the inhibition of pertechnetate uptake was approximately micromolar.

CONCLUSION

We have produced a human colon cell line with a stable constitutive expression of functional hNIS (HCT116-hNIS-C19). [18F]-tetrafluoroborate accumulates in cells expressing hNIS or rat sodium/iodide symporter and is a potential PET imaging agent in thyroid disease and hNIS reporter gene imaging.

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.

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.

[Study on the iodine 125 uptake of H460 lung cancer cell line by co-transfection with the human sodium/iodide symporter and the human thyroperoxidase]

BACKGROUND AND OBJECTIVE

Lung cancer harms people's health or even lives severely. Especially, the therapy of non-small cell lung cancer (NSCLC) has not been obviously improved for many years. The aim of this study is to transfer the human sodium/iodide symporter (hNIS) and the human thyroperoxidase (hTPO) genes into H460 lung cancer cell line, and to study the uptake ability of iodide after co-transfected hTPO and hNIS gene in cell lines.

METHODS

Through cloning, recombination, packaging and amplifying, the recombinant adenosine virus (AdTPO) was constructed. Then the protein expression of AdTPO was tested by Western blot. After transfected hNIS gene into human lung cancer cell line H460 through liposome, stably expressing hNIS gene cell lines (hNIS-H460) selected by G418 antibiotics was determined as hNIS-H460 group. Using AdTPO, hTPO gene was transducted into hNIS-H460, as AdTPO-hNIS-H460 group. H460 cell without hNIS gene was applied as control group (H460). Then, we investigated the 125I uptake assay of the above cells.

RESULTS

We were successful in co-transfecting hNIS and hTPO gene into human lung cell lines H460, and were obtained hNIS and hTPO gene lung cancer cell lines (hNIS-H460 and AdTPO-hNIS-H460). In AdTPO-hNIS-H460, hNIS-H460 and H460, the uptake ability of 125I was (59 637.67 +/- 1 281.13), (48 622.17 +/- 2 242.28) and (1 440.17 +/- 372.86) counts x min(-1). The uptake ability of 125I was 41 fold higher in AdTPO-hNIS-H460 than in blank control H460 (P < 0.01), and 34 fold higher in hNIS-460 than in blank control H460 (P < 0.01), and 1.2 fold higher in AdTPO-hNIS-H460 than in hNIS-H460 (P < 0.01).

CONCLUSION

The uptake ability of 125I could increase by co-transfected hNIS and hTPO genes into human lung cancer cell lines H460.

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.

A probasin promoter, conditionally replicating adenovirus that expresses the sodium iodide symporter (NIS) for radiovirotherapy of prostate cancer

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. We have extended the use of NIS-mediated radioiodine therapy to other types of cancer, we transferred and expressed the sodium-iodide symporter (NIS) gene into prostate, colon, and breast cancer cells using adenoviral vectors. To improve vector efficiency we have developed a conditionally replicating adenovirus (CRAd) in which the E1a gene is driven by the prostate specific promoter, Probasin and the cassette RSV promoter-human NIScDNA-bGH polyA replaces the E3 region (CRAd Ad5PB_RSV-NIS). In vitro infection of the prostate cancer cell line LnCaP resulted in virus replication, cytolysis, and release of infective viral particles. Conversely, the prostate cancer cell line PC-3 (androgen receptor negative) and the pancreatic cancer cell line Panc-1 were refractory to the viral cytopathic effect and did not support viral replication. Radioiodine uptake was readily measurable in LnCaP cells infected with Ad5PB_RSV-NIS 24 hours post-infection, confirming NIS expression. In vivo, LnCaP tumor xenografts in nude mice injected intratumorally with Ad5PB_RSV_NIS CRAd expressed NIS actively as evidenced by ⁹⁹Tc uptake and imaging. Administration of therapeutic ¹³¹I after virus injection significantly increased survival probability in mice carrying xenografted LnCaP tumors compared to virotherapy alone. The data indicate that Ad5PB_RSV_NIS replication is stringently restricted to androgen positive prostate cancer cells and results in effective NIS expression and uptake of radioiodine. This construct may allow multimodal therapy, combining cytolytic virotherapy with radioiodine treatment, to be developed as a novel treatment for prostate cancer.

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.

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.

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.

Construction of an MUC-1 promoter driven, conditionally replicating adenovirus that expresses the sodium iodide symporter for gene therapy of breast cancer

Introduction

The sodium iodide symporter (NIS) directs the uptake and concentration of iodide in thyroid cells. This in turn allows radioiodine imaging and therapy for thyroid cancer. To extend the use of NIS-mediated radioiodine therapy to other types of cancer, we successfully transferred and expressed the sodium-iodide symporter (NIS) gene in prostate, colon, and breast cancer cells both in vivo and in vitro by using non-replicating adenoviral vectors.

Methods

To improve virotherapy efficiency, we developed a conditionally replicating adenovirus (CRAd) in which the transcriptional cassette RSV promoter-human NIScDNA-bGH polyA was also inserted at the E3 region. The E1a gene is driven by the tumor-specific promoter MUC-1 in the CRAd Ad5AMUCH_RSV-NIS.

Results

In vitro infection of the MUC-1-positive breast cell line T47D resulted in virus replication, cytolysis, and release of infective viral particles. Conversely, the MUC-1-negative breast cancer cell line MDA-MB-231 was refractory to the viral cytopathic effect and did not support viral replication. The data indicate that Ad5AMUCH_RSV-NIS activity is stringently restricted to MUC-1-positive cancer cells. Radioiodine uptake was readily measurable in T47 cells infected with Ad5AMUCH_RSV-NIS 24 hours after infection, thus confirming NIS expression before viral-induced cell death.

Conclusions

This construct may allow multimodal therapy, combining virotherapy with radioiodine therapy to be developed as a novel treatment for breast and other MUC1-overexpressing cancers.

Radioiodine gene therapy of hepatocellular carcinoma targeted human alpha fetoprotein

INTRODUCTION

We conducted a molecular imaging and gene therapy method in alpha-fetoprotein (AFP)-producing hepatocellular carcinoma (HCC) by tumor-specific expression of the human sodium/iodide symporter (hNIS) using an AFP promoter.

METHODS

The tumor-specific expression of hNIS gene by the AFP enhancer/promoter was constructed as pcDNA3-AFP/hNIS. The pcDNA3-AFP/hNIS was stably transfected to human HCC (Huh-7/AN) and rat glioma cells (C6/AN). Functional hNIS expression was confirmed by radioiodine uptake. The mRNA and protein-expression level of hNIS were measured. Biodistribution of 131I was evaluated, and scintigraphic images of 99mTc were obtained in xenografted mice. A clonogenic assay was performed by 131I. And, the in vivo therapeutic effect of 131I was evaluated in xenografted mice.

RESULTS

In Huh-7/AN cells, iodine was highly accumulated and completely blocked by perchlorate. The protein and mRNA expression levels were correlated with iodine uptake. Radioiodine uptake in Huh-7/AN tumors was higher than those of control tumors and clearly visualized. The survival rate was significantly decreased in Huh-7/AN cells by 131I. Moreover, a growth of Huh-7/AN tumors was inhibited by 131I in mice.

CONCLUSIONS

AFP-producing hepatoma can be targeted and treated with radionuclides and hNIS, using AFP enhancer/promoter. This targeted hNIS gene therapy and molecular imaging have the potential to be used in the management of AFP-producing HCC.

Internal radiotherapy of liver cancer with rat hepatocarcinoma-intestine-pancreas gene as a liver tumor-specific promoter

The hepatocarcinoma-intestine-pancreas (HIP) gene, also called pancreatitis-associated protein-1 (PAP1) or Reg IIIalpha, is activated in most human hepatocellular carcinomas (HCCs) but not in normal liver, which suggests that HIP regulatory sequence could be used as efficient liver tumor-specific promoters to express a therapeutic polynucleotide in liver cancer. The sodium iodide symporter (NIS), which has recognized therapeutic and reporter gene properties, is appropriate to evaluate the transcriptional strength and specificity of the HIP promoter in HCC. For this purpose, we constructed a recombinant rat HIP-NIS adenoviral vector (AdrHIP-NIS), and evaluated its performance as a mediator of selective radioiodide uptake in tumor hepatocytes. Western blot, immunofluorescence, and iodide uptake assays were performed in AdrHIP-NIS-infected primary hepatocytes and transformed hepatic and nonhepatic cells. Nuclear imaging, tissue counting and immunohistochemistry were performed in normal and HCC-bearing Wistar rats infected with AdrHIP-NIS intratumorally or via the hepatic artery. In AdrHIP-NIS-infected transformed hepatic cells, functional NIS was strongly expressed, as in cells infected with a cytomegalovirus-NIS vector. No NIS expression was found in AdrHIP-NIS-infected normal hepatocytes or transformed nonhepatic cells. In rats bearing multinodular HCC, AdrHIP-NIS triggered functional NIS expression that was preferential in tumor hepatocytes. Administration of 18 mCi of (131)I resulted in the destruction of AdrHIP-NIS-injected nodules. This study has identified the rHIP regulatory sequence as a potent liver tumor-specific promoter for the transfer of therapeutic genes, and AdrHIP-NIS-mediated (131)I therapy as a valuable option for the treatment of multinodular HCC.

Enhanced iodide sequestration by 3-biphenyl-5,6-dihydroimidazo[2,1-b]thiazole in sodium/iodide symporter (NIS)-expressing cells

The ability of the sodium/iodide symporter (NIS) to take up iodide has long provided the basis for cytoreductive gene therapy and cancer treatment with radioiodide. One of the major limitations of this approach is that radioiodide retention in NIS-expressing cells is not sufficient for their destruction. We identified and characterized a small organic molecule capable of increasing iodide retention in HEK293 cells permanently transfected with human NIS cDNA (hNIS-HEK293) and in the rat thyroid-derived cell line FRTL-5. In the presence of 3-biphenyl-4'-yl-5,6-dihydroimidazo[2,1-b]thiazole (ISA1), the transmembrane iodide concentration gradient was increased up to 4.5-fold. Our experiments indicate that the imidazothiazole derivative acts either by inhibiting anion efflux mechanisms, or by promoting the relocation of iodide into subcellular compartments. This new compound is not only an attractive chemical tool to investigate the mechanisms of iodide flux at the cellular level, but also opens promising perspectives in the treatment of cancer after NIS gene transfer.

Synergistic tumoricidal effect of combined hMUC1 vaccination and hNIS radioiodine gene therapy

We examined the merits of combinatorial hMUC1 vaccination and hNIS radioiodine gene therapy and evaluated its tumoricidal effects in an animal tumor model. CMNF (CT26 expressing hMUC1, hNIS, and firefly luciferase) cells were transplanted into 28 mice, and 4 and 11 days after tumor challenge, tumor-bearing mice were immunized i.m. with pcDNA3.1 or pcDNA-hMUC1 vaccine and subsequently administered PBS or (131)I i.p. [four groups (7 mice per group): pcDNA3.1 + PBS, phMUC1 + PBS, pcDNA3.1 + (131)I, and phMUC1 + (131)I groups]. Thirty-two days after tumor challenge, we rechallenged mice in the pcDNA3.1 + (131)I and phMUC1 + (131)I groups with CMNF cells. Tumor progression and tumor-free mice (%) were monitored by bioluminescence. We investigated hMUC1-associated immune response generated by combination therapy. Marked tumor growth inhibition was observed in the phMUC1 + (131)I group by bioluminescence at 32 days after tumor challenge. Mice in phMUC1 + (131)I group showed complete hMUC1-expressing tumor suppression after tumor rechallenge, whereas mice in the pcDNA3.1 + (131)I group did not. The tumor-free mice (%) were much higher in the phMUC1 + (131)I group than in the other three groups. Levels of hMUC1-associated CD8(+)IFN-gamma(+) T cells were higher in the phMUC1 + (131)I group than in the other three groups. hMUC1-loaded CD11(+) cells in the phMUC1 + (131)I group were found to be most effective at generating hMUC1-associated CD8(+)IFN-gamma(+) T cells. The activities of hMUC1-associated cytotoxic T cells in the phMUC1 + (131)I group were higher than in the other three groups. Our data suggest that phMUC1 + (131)I combination therapy synergistically generates marked tumoricidal effects against established hMUC1-expressing cancers.

PET imaging of heat-inducible suicide gene expression in mice bearing head and neck squamous cell carcinoma xenografts

The ability to achieve tumor selective expression of therapeutic genes is an area that needs improvement for cancer gene therapy to be successful. One approach to address this is through the use of promoters that can be controlled by external means, such as hyperthermia. In this regard, we constructed a replication-deficient adenovirus that consists of a mutated herpes simplex virus 1 thymidine kinase (mTK) fused to enhanced green fluorescent protein (EGFP) under the control of the full-length human heat shock (HS) 70b promoter. The virus (AdHSmTK-EGFP) was evaluated both in vitro and in vivo in oral squamous cell carcinoma SCC-9 cells for expression of both mTK and EGFP. The in vitro expression of mTK-EGFP was validated using both (3)H-penciclovir and fluorescence-activated cell sorting assays. These studies show that specific expression could be achieved by heating the cells at 41 degrees C for 1 h, whereas little expression was observed using high doses of virus without hyperthermia. The vector was also evaluated in vivo by direct intratumoral injection into mice bearing SCC-9 xenografts. These studies demonstrated tumor expression of mTK-EGFP after ultrasound heating of the tumors by radioactive biodistribution assays, histology and microPET imaging. These in vivo results, which demonstrate HS-inducible transgene expression using PET imaging, provide a means for noninvasive monitoring of heat-induced gene therapy in local tumors, such as oral squamous cell carcinomas.

Radiation-mediated up-regulation of gene expression from replication-defective adenoviral vectors: implications for sodium iodide symporter gene therapy

PURPOSE

To assess the effects of external beam radiotherapy (EBRT) on adenoviral-mediated transgene expression in vitro and in vivo and to define an optimal strategy for combining sodium iodide symporter (NIS)-mediated (131)I therapy with EBRT.

EXPERIMENTAL DESIGN

Expression of reporter genes [NIS, green fluorescent protein (GFP), beta-galactosidase (lacZ), and luciferase (Luc)] from replication-deficient adenoviruses was assessed in tumor cell lines under basal conditions and following irradiation. The effects of viral multiplicity of infection (MOI) and EBRT dose on the magnitude and duration of gene expression were determined. In vivo studies were done with Ad-CMV-GFP and Ad-RSV-Luc.

RESULTS

EBRT increased NIS, GFP, and beta-galactosidase expression in colorectal, head and neck, and lung cancer cells. Radiation dose and MOI were important determinants of response to EBRT, with greatest effects at higher EBRT doses and lower MOIs. Radiation exerted both transductional (through increased coxsackie-adenoviral receptor and integrin alpha(v)) and nontransductional effects, irrespective of promoter sequence (CMV, RSV, hTR, or hTERT). Analysis of the schedule of EBRT followed by viral infection revealed maximal transduction at 24 hours. Radiation maintained increasing radioiodide uptake from Ad-hTR-NIS over 6 days, in direct contrast to reducing levels in unirradiated cells. The effects of EBRT in increasing and maintaining adenovirus-mediated transgene expression were also seen in vivo using GFP- and luciferase-expressing adenoviral vectors.

CONCLUSIONS

Radiation increased the magnitude and duration of NIS gene expression from replication-deficient adenoviruses. The transductional effect is maximal at 24 hours, but radioiodide uptake is maintained at an elevated level over 6 days after infection.

The potential of 211Astatine for NIS-mediated radionuclide therapy in prostate cancer

PURPOSE

We reported recently the induction of selective iodide uptake in prostate cancer cells (LNCaP) by prostate-specific antigen (PSA) promoter-directed sodium iodide symporter (NIS) expression that allowed a significant therapeutic effect of (131)I. In the current study, we studied the potential of the high-energy alpha-emitter (211)At, also transported by NIS, as an alternative radionuclide after NIS gene transfer in tumors with limited therapeutic efficacy of (131)I due to rapid iodide efflux.

METHODS

We investigated uptake and therapeutic efficacy of (211)At in LNCaP cells stably expressing NIS under the control of the PSA promoter (NP-1) in vitro and in vivo.

RESULTS

NP-1 cells concentrated (211)At in a perchlorate-sensitive manner, which allowed a dramatic therapeutic effect in vitro. After intraperitoneal injection of (211)At (1 MBq), NP-1 tumors accumulated approximately 16% ID/g (211)At (effective half-life 4.6 h), which resulted in a tumor-absorbed dose of 1,580+/-345 mGy/MBq and a significant tumor volume reduction of up to 82+/-19%, while control tumors continued their growth exponentially.

CONCLUSIONS

A significant therapeutic effect of (211)At has been demonstrated in prostate cancer after PSA promoter-directed NIS gene transfer in vitro and in vivo suggesting a potential role for (211)At as an attractive alternative radioisotope for NIS-targeted radionuclide therapy, in particular in smaller tumors with limited radionuclide retention time.

Image-guided radioiodide therapy of medullary thyroid cancer after carcinoembryonic antigen promoter-targeted sodium iodide symporter gene expression

In contrast to follicular cell-derived thyroid cancer, medullary thyroid cancer (MTC) remains difficult to treat because of its unresponsiveness to radioiodine therapy, or to conventional chemo- and radiotherapy. We therefore examined the feasibility of radioiodine therapy of MTC after human sodium iodide symporter (hNIS) gene transfer, using the tumor-specific carcinoembryonic antigen (CEA) promoter for transcriptional targeting. NIS gene transfer was performed in vivo in human MTC cell (TT) xenografts, using adenoviral vectors carrying the NIS gene linked to the cytomegalovirus promoter (Ad5-CMV-NIS) or a CEA promoter fragment (Ad5-CEA-NIS). Functional NIS expression was confirmed by immunostaining as well as in vivo (123)I gamma-camera imaging followed by application of a therapeutic (131)I dose. TT cell xenografts in nude mice injected intratumorally with Ad5-CEA-NIS accumulated 7.5 +/- 1.2% ID/g (percentage injected dose per gram tumor tissue; 5 x 10(8) PFU) and 12 +/- 2.95% ID/g (1 x 10(9) PFU) with an average biological half-life of 6.1 +/- 0.8 and 23.6 +/- 3.7 hr, respectively, as compared with accumulation of 8.4 +/- 0.9% ID/g with a biological half-life of 12 +/- 8 hr after application of Ad5-CMV-NIS (5 x 10(8) PFU). After Ad5-CEA-NIS-mediated NIS gene transfer in TT cell xenografts administration of a therapeutic dose of 111 MBq (3 mCi) of (131)I resulted in a significant reduction of tumor growth associated with significantly lower calcitonin serum levels in treated mice as well as improved survival. We conclude that a therapeutic effect of (131)I was demonstrated in vivo in MTC cell xenografts after adenovirus-mediated induction of tumor-specific iodide accumulation by CEA promoter-directed hNIS expression.