Combination Therapy and Noninvasive Imaging with a Dual Therapeutic Vector Expressing MDR1 Short Hairpin RNA and a Sodium Iodide Symporter

Thermodynamic and cellular studies of doxorubicin/daunorubicin loaded by a DNA tetrahedron for diagnostic imaging, chemotherapy, and gene therapy

The combined diagnostic imaging, chemotherapy, and gene therapy based on DNA nanocarriers can reduce the toxic side effects and overcome multidrug resistance (MDR). In this study, we designed an antisense oligonucleotides (ASOs)-linked DNA tetrahedron (ASOs-TD). The detection limit of ASOs-TD for MDR1 mRNA was 0.05 μM. By using fluorescence spectroscopy and isothermal titration calorimetry (ITC), the interactions between doxorubicin (DOX) /daunorubicin (DAU) and ASOs-TD were investigated. The number of binding sites (n), binding constant (Ka), entropy change (ΔSo), enthalpy change (ΔHo) and Gibbs free energy change (ΔGo) were obtained. The intercalation of DOX/DAU with ASOs-TD was demonstrated by differential scanning calorimetry (DSC) and quenching researches of potassium ferricyanide K4[Fe(CN)6]. The in vitro release rate of DOX/DAU loaded in ASOs-TD was accelerated by deoxyribonuclease I (DNase I). In vitro cytotoxicity proved the good gene therapy effect of ASOs-TD and the increased cytotoxicity of DOX/DAU to MCF-7/ADR cells. The results of confocal laser scanning microscope (CLSM) suggested that ASOs-TD could effectively identify drug-resistant cells due to its good imaging ability for MDR1 mRNA. This work offers theoretical significance for overcoming MDR using DNA nanostructures which combine diagnostic imaging, chemotherapy, and gene therapy.

Iodine-124 PET quantification of organ-specific delivery and expression of NIS-encoding RNA

Background

RNA-based vaccination strategies tailoring immune response to specific reactions have become an important pillar for a broad range of applications. Recently, the use of lipid-based nanoparticles opened the possibility to deliver RNA to specific sites within the body, overcoming the limitation of rapid degradation in the bloodstream. Here, we have investigated whether small animal PET/MRI can be employed to image the biodistribution of RNA-encoded protein. For this purpose, a reporter RNA coding for the sodium-iodide-symporter (NIS) was in vitro transcribed in cell lines and evaluated for expression. RNA-lipoplex nanoparticles were then assembled by complexing RNA with liposomes at different charge ratios, and functional NIS protein translation was imaged and quantified in vivo and ex vivo by Iodine-124 PET upon intravenous administration in mice.

Results

NIS expression was detected on the membrane of two cell lines as early as 6 h after transfection and gradually decreased over 48 h. In vivo and ex vivo PET/MRI of anionic spleen-targeting or cationic lung-targeting NIS-RNA lipoplexes revealed a visually detectable rapid increase of Iodine-124 uptake in the spleen or lung compared to control-RNA-lipoplexes, respectively, with minimal background in other organs except from thyroid, stomach and salivary gland.

Conclusions

The strong organ selectivity and high target-to-background acquisition of NIS-RNA lipoplexes indicate the feasibility of small animal PET/MRI to quantify organ-specific delivery of RNA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13550-021-00753-2.

Imaging CXCR4 Expression with (99m)Tc-Radiolabeled Small-Interference RNA in Experimental Human Breast Cancer Xenografts

PURPOSE

Noninvasive quantification of chemokine receptor 4 (CXCR4) expression could serve as a prognostic indicator and may be of value for the design of personalized therapies and posttreatment monitoring. The objective of the present study was to assess the use of (99m)Tc-radiolabeled small-interference RNA (siRNA) targeting CXCR4 to detect CXCR4 expression in vivo.

PROCEDURES

CXCR4 siRNAs were radiolabeled with (99m)Tc using the bifunctional chelator hydrazinonicotinamide (HYNIC), and the labeling efficiency, specific activity and radiochemical purity were determined. The stability of the probe in serum was assessed by measuring its radiochemical purity and inhibitory activity by RT-PCR and western blotting. Biodistribution studies and static imaging were performed in MDA-MB-231 tumor-bearing mice.

RESULTS

Radiochemical purity remained highly stable in PBS and fresh human serum at room temperature and at 37 °C. Radiolabeled siRNA1 showed strong inhibitory effects similar to those of unlabeled siRNA1 on both CXCR4 messenger RNA (mRNA) and protein in vitro. The excretion of the probe occurred mainly through the liver and kidneys. Tumors were clearly visualized at 1-10 h after injection of the probe, but not after injection of the control probe.

CONCLUSIONS

(99m)Tc-labeled CXCR4 siRNA1 shows tumor-specific accumulation and could be a promising strategy for the visualization of CXCR4 expression in human breast cancer.

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.

Complementary treatment of siTERT for improving the antitumor effect of TERT-specific I-131 therapy

Sodium iodide symporter (NIS)-based radionuclide therapy provides an effective means of treating malignant tumors. However, it is sometimes inadequate because of limited effects on radio-resistant tumors, and thus, combination therapies with other therapeutic options have been requested to enhance its efficacy. Human telomerase reverse transcriptase (hTERT) has been reported to be involved in the progression of most cancers and also been viewed as a good candidate for targeting tumor. Application of TERT-specific radionuclide therapies using NIS gene transfer have been reported to treat TERT-positive tumors, but this approach only demonstrated tumor regression rather than eradication. As inhibiting TERT expression by introducing the hTERT-specific shRNA (siTERT) has been suggested as a therapeutic option, we investigated the complementary role of siTERT treatment after the TERT-specific I-131 therapy and its possibility as a novel anticancer therapeutic strategy. Retroviruses containing TERT promoter/NIS for TERT specific Radionuclide therapy and siTERT for TERT targeting antisense therapy were produced. Hep3B cells expressing TERT specific NIS (Hep3B-TERT/NIS) were xenografted into nude mouse and visualized with micro-SPECT/CT for monitoring NIS activity. The levels of hTERT mRNA, protein and its activity were confirmed by RT-PCR, Western blotting and Telomerase repeat amplification protocol assay. Cell proliferation was monitored by MTT assay and induced apoptosis was confirmed by Annexin-V-PI staining. Therapeutic effects of I-131 and/or siTERT were evaluated by clonogenic assay and mouse tumor model. Reduction of hTERT mRNA, protein and TERT activity by siTERT were observed in Hep3B-TERT/NIS cells. The viabilities of the infected cells were significantly decreased to 50% versus siScramble treated controls. The early apoptotic cell population was increased by siTERT. The survival rates of cells treated with siTERT or I-131 alone were 72.4±7.6% and 56.2±5.2%, respectively. However, the survival rate of cells treated with I-131 and siTERT were decreased to 22.1±2.8%. From mouse xenograft model, we also found that the siTERT gene therapy showed synergism to the radioiodine therapy for reducing tumor growth in vivo. Our Results suggested that complementary siTERT gene therapy offers a novel strategy of cancer therapy to improve the therapeutic efficacy of TERT-specific I-131.

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.

Evaluation of the therapeutic efficacy of a VEGFR2-blocking antibody using sodium-iodide symporter molecular imaging in a tumor xenograft model

PURPOSE

Vascular endothelial growth factor receptor 2-blocking antibody (DC101) has inhibitory effects on tumor growth and angiogenesis in vivo. The human sodium/iodide symporter (hNIS) gene has been shown to be a useful molecular imaging reporter gene. Here, we investigated the evaluation of therapeutic efficacy by molecular imaging in reporter gene transfected tumor xenografts using a gamma imaging system.

METHODS

The hNIS gene was transfected into MDA-MB-231 cells using Lipofectamine. The correlation between the number of MDA-MB-231-hNIS cells and the uptake of (99m)Tc-pertechnetate or (125)I was investigated in vitro by gamma imaging and counting. MDA-MB-231-hNIS cells were injected subcutaneously into mice. When the tumor volume reached 180-200 mm(3), we randomly assigned five animals to each of three groups representing different tumor therapies; no DC101 (control), 100 μg, or 150 μg DC101/mouse. One week and 2 weeks after the first injection of DC101, gamma imaging was performed. Mice were sacrificed 2 weeks after the first injection of DC101. The tumor tissues were used for reverse transcriptase-polymerase chain reaction (RT-PCR) and CD31 staining.

RESULTS

Uptake of (125)I and (99m)Tc-pertechnetate into MDA-MB-231-hNIS cells in vitro showed correlation with the number of cells. In DC101 treatment groups, the mean tumor volume was smaller than that of the control mice. Furthermore, tumor uptake of (125)I was lower than in the controls. The CD31 staining and RT-PCR assay results showed that vessel formation and expression of the hNIS gene were significantly reduced in the tumor tissues of treatment groups.

CONCLUSION

This study demonstrated the power of molecular imaging using a gamma imaging system for evaluating the therapeutic efficacy of an antitumor treatment. Molecular imaging systems may be useful in evaluation and development of effective diagnostic and/or therapeutic antibodies for specific target molecules.

Noninvasive visualization of RNA delivery with 99mTc-radiolabeled small-interference RNA in tumor xenografts

Small-interference RNAs (siRNAs) are short, double-strand RNA molecules that target specific messenger RNAs for degradation via the process termed RNA interference. The efficacy of RNA interference depends greatly on effective delivery of siRNA, which calls for noninvasive methods for tracing siRNA in vivo. The purpose of this work was to develop a novel (99m)Tc-radiolabeled method to visualize siRNA targeting of a tumor biomarker of human telomerase reverse transcriptase (hTERT) in HepG2 tumor xenografts.

METHODS

After conjugation with S-acetyl N-hydroxysuccinimide-mercaptoacetyltriglycine (NHS-MAG3), antisense RNA with 2'-O-methyl modification was annealed with sense strand to form a duplex and then radiolabeled with (99m)Tc. (99m)Tc-siRNAs were tested for stability in serum by measurement of radiochemical purity and for inhibitory activity by reverse-transcriptase polymerase chain reaction and Western blotting. In vitro cellular uptake was evaluated in HepG2 cells. Biodistribution studies and static imaging were performed in HepG2 tumor-bearing mice.

RESULTS

Radiochemical purity remained highly stable in saline and fresh human serum at room temperature and 37 degrees C. Radiolabeled siRNA demonstrated strong inhibitory effects similar to those of unlabeled siRNA on both hTERT messenger RNA and protein in vitro. (99m)Tc-hTERT siRNA showed more uptake than did control siRNA in HepG2 cells after 1 h of incubation. After administration in HepG2 tumor-bearing mice, (99m)Tc-hTERT siRNA had significantly higher accumulation in tumors and a higher tumor-to-blood ratio than did control siRNA (P < 0.05). Scintigraphy of (99m)Tc-hTERT siRNA showed clear tumor images at 0.5, 1, 3, and 6 h after injection. In contrast, (99m)Tc-control siRNA failed to visualize the tumor. Ratios of uptake in tumor to uptake in contralateral region of hTERT-targeted siRNA were significantly higher than those of control siRNA (P < 0.05) at each time point.

CONCLUSION

The (99m)Tc radiolabeling method with NHS-MAG3 chelator can be used successfully in siRNA radiolabeling, allowing for the noninvasive visualization of siRNA delivery in vivo.

Synthetic radiation-inducible promoters mediated HSV-TK/GCV gene therapy in the treatment of oral squamous cell carcinoma

OBJECTIVE

To investigate the therapeutic effect of herpes simplex virus thymidine kinase (HSV-TK) gene mediated by synthetic radiation-inducible promoters in the treatment of oral squamous cell carcinoma (OSCC) in vitro and in vivo.

METHODS

The plasmids pcDNA3.1(+)E6-HSV-TK were constructed, in which the HSV-TK genes were mediated by synthetic radiation-inducible promoters. The recombined plasmids were transfected into the Tca8113 cells and golden hamster buccal carcinoma, respectively. Low-dose radiotherapy was used to upregulate the HSV-TK genes expression. HSV-TK mRNA was assayed by RT-PCR. Apoptosis and proliferating cell nuclear antigen were detected respectively by in situ end-labeling and immunohistochemical method.

RESULTS

Compared with control group, the comparative survival rate of Tca8113 cells in HSV-TK/GCV/IR group was markedly decreased and the golden hamster buccal carcinoma in HSV-TK/GCV/IR group was obviously suppressed. Up-regulation of HSV-TK gene expression was found in the Tca8113 cells and in the golden hamster buccal carcinoma resulting from exposure to low-dose irradiation. The apoptosis indexes in Tca8113 cells or golden hamster buccal carcinoma with irradiation were markedly higher than those without irradiation. At the same time, the proliferation indexes in Tca8113 cells or golden hamster buccal carcinoma with irradiation were markedly lower than those without irradiation.

CONCLUSION

The results indicate that the synthetic radiation-inducible promoters can serve as a molecular switch to adjust the expression of HSV-TK gene in the treatment of OSCC, and low-dose induction radiation can significantly improve therapeutic efficiency.

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 radiotherapy for prostate cancer with an oncolytic adenovirus coding for human sodium iodide symporter

PURPOSE

Oncolytic adenoviruses are promising tools for cancer therapy. Although several clinical reports have indicated both safety and promising antitumor capabilities for these viruses, there are only a few examples of complete tumor eradication. Thus, the antitumor efficacy of oncolytic adenoviruses needs to be improved. One potentially useful approach is combination with radiotherapy.

EXPERIMENTAL DESIGN

To target systemically administered radioiodide to tumors, we created Ad5/3-Delta24-human sodium iodide symporter (hNIS), a Rb-p16 pathway selective infectivity enhanced oncolytic adenovirus encoding hNIS.

RESULTS

Ad5/3-Delta24-hNIS replication effectively killed prostate cancer cells in vitro and in vivo. Also, the virus-mediated radioiodide uptake into prostate cancer cells in vitro and into tumors in vivo. Furthermore, Ad5/3-Delta24-hNIS with radioiodide was significantly more effective than virus alone in mice with prostate cancer xenografts.

CONCLUSIONS

These results suggest that oncolytic adenovirus-mediated targeted radiotherapy might be a potentially useful option for enhancing the efficacy or adenoviral virotherapy.

Methods to monitor gene therapy with molecular imaging

Recent progress in scientific and clinical research has made gene therapy a promising option for efficient and targeted treatment of several inherited and acquired disorders. One of the most critical issues for ensuring success of gene-based therapies is the development of technologies for non-invasive monitoring of the distribution and kinetics of vector-mediated gene expression. In recent years many molecular imaging techniques for safe, repeated and high-resolution in vivo imaging of gene expression have been developed and successfully used in animals and humans. In this review molecular imaging techniques for monitoring of gene therapy are described and specific use of these methods in the different steps of a gene therapy protocol from gene delivery to assessment of therapy response is illustrated. Linking molecular imaging (MI) to gene therapy will eventually help to improve the efficacy and safety of current gene therapy protocols for human application and support future individualized patient treatment.