The effect of lentiviral vector-mediated RNA interference targeting hypoxia-inducible factor 1α on the uptake of fluorodeoxyglucose ((18)f) in the human pancreatic cancer cell line, patu8988

Transcriptional Targeting and MicroRNA Regulation of Lentiviral Vectors

Gene expression regulation is the result of complex interactions between transcriptional and post-transcriptional controls, resulting in cell-type-specific gene expression patterns that are determined by the developmental and differentiation stage of pathophysiological conditions. Understanding the complexity of gene expression regulatory networks is fundamental to gene therapy, an approach which has the potential to treat and cure inherited disorders by delivering the correct gene to patient specific cells or tissues by means of both viral and non-viral vectors. Besides the issues of biosafety, in recent years efforts have focused on achieving a robust and sustained transgene expression, which attains a phenotypic correction in several diseases, while avoiding transgene-related adverse effects, such as overexpression-associated cytotoxicity and/or immune responses to the transgene. In this sense, the use of cell-type-specific promoters and microRNA target sequences (miRTs) in gene transfer expression cassettes have allowed for a restricted expression after gene transfer in several studies. This review will focus on the use of transcriptional and post-transcriptional regulation to achieve a highly specific and safe transgene expression, as well as their application in ex vivo and in vivo gene therapeutic approaches.

The Distribution and Imaging of 99mTc-nGO-PEG-FA in Human Patu8988 Tumor-Bearing Nude Mice

Background: To study the distribution and imaging of ^99mTc-nGO-PEG-FA in human pancreatic cancer Patu8988 tumor-bearing nude mice, and to explore its usefulness as an imaging reagent for pancreatic cancer. Materials and Methods: Natural graphite powder was used as raw material to prepare the nanosized graphene oxide (nGO) by using the modified Hummers method, and then was covalently modified by polyethylene glycol (PEG) on the surface of nGO. The nGO was further optimized by in vitro cell experiment, and then conjugated with the targeting molecule folic acid (FA) to form nGO-PEG-FA system. The nGO-PEG-FA was finally labeled by radioactive nuclide ^99mTc by direct labeling method to form the ^99mTc-nGO-PEG-FA molecular imaging probe. Nude mice bearing patu8988 pancreatic cancer xenografts were intravenous injection (I.V.) injected with ^99mTc-nGO-PEG-FA, and the distribution of ^99mTc-nGO-PEG-FA in nude mice at different time course was investigated by determination of tissue uptake of radioactivity (%ID/g), as well as the single photon emission computed tomography (SPECT) imaging at different time course. Results: The labeling rate of nGO-PEG-FA with ^99mTc was (90.08 ± 2.34)%, and the highest binding rate of ^99mTc-nGO-PEG-FA with Patu8988 cells was (3.15 ± 0.31)%. The radioactive uptake in tumor reached (5.11 ± 1.23)%ID/g at 6 h after I.V. injection of ^99mTc-nGO-PEG-FA in nude mice. Meanwhile, the radioactive uptake in liver, spleen, and lung was also high and reached (10.33 ± 1.22)%ID/g, (5.86 ± 0.59)%ID/g, and (3.55 ± 0.93)%ID/g, respectively, whereas less radioactivity uptake was observed in the heart (1.12 ± 0.33)%ID/g and blood (2.76 ± 0.39)%ID/g, respectively. The tumors can be clearly imaged at 4.0-6.0 h after ^99mTc-nGO-PEG-FA injection. Conclusions: ^99mTc-nGO-PEG-FA can efficiently target pancreatic cancer, which may be developed as an imaging agent for pancreatic cancer.

In vivo evaluation of the effects of simultaneous inhibition of GLUT-1 and HIF-1α by antisense oligodeoxynucleotides on the radiosensitivity of laryngeal carcinoma using micro 18F-FDG PET/CT

Purpose

Hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (GLUT-1) are two important hypoxic markers associated with the radioresistance of cancers including laryngeal carcinoma. We evaluated whether the simultaneous inhibition of GLUT-1 and HIF-1α expression improved the radiosensitivity of laryngeal carcinoma. We explored whether the expression of HIF-1α and GLUT-1 was correlated with 2′-deoxy-2’-[18F]fluoro-D-glucose (¹⁸F-FDG) uptake and whether ¹⁸F-FDG positron emission tomography-computed tomography (PET/CT) was appropriate for early evaluation of the response of laryngeal carcinoma to targeted treatment in vivo.

Materials and Methods

To verify the above hypotheses, an in vivo model was applied by subcutaneously injecting Hep-2 (2 × 107/mL × 0.2 mL) and Tu212 cells (2 × 107/mL × 0.2 mL) into nude mice. The effects of HIF-1α antisense oligodeoxynucleotides (AS-ODNs) (100 μg) and GLUT-1 AS-ODNs (100 μg) on the radiosensitivity of laryngeal carcinoma were assessed by tumor volume and weight, microvessel density (MVD), apoptosis index (AI) and necrosis in vivo based on a full factorial (2³) design. ¹⁸F-FDG-PET/CT was taken before and after the treatment of xenografts. The relationships between HIF-1α and GLUT-1 expression and ¹⁸F-FDG uptake in xenografts were estimated and the value of ¹⁸F-FDG-PET/CT was assessed after treating the xenografts.

Results

10 Gy X-ray irradiation decreased the weight of Hep-2 xenografts 8 and 12 days after treatment, and the weights of Tu212 xenografts 8 days after treatment. GLUT-1 AS-ODNs decreased the weight of Tu212 xenografts 12 days after treatment. There was a synergistic interaction among the three treatments (GLUT-1 AS-ODNs, HIF-1α AS-ODNs and 10Gy X-ray irradiation) in increasing apoptosis, decreasing MVD, and increasing necrosis in Hep-2 xenografts 8 days after treatment (p < 0.05) and in Tu212 xenografts 12 days after treatment (p < 0.001). Standardized uptake value (tumor/normal tissue)( SUVmaxT/N) did not show a statistically significant correlation with GLUT1 and HIF-1α expression and therapeutic effect (necrosis, apoptosis).

Conclusions

Simultaneous inhibition of HIF-1α and GLUT-1 expression might increase the radiosensitivity of laryngeal carcinoma, decreasing MVD, and promoting apoptosis and necrosis. ¹⁸F-FDG-PET/CT wasn't useful in evaluating the therapeutic effect on laryngeal cancer in this animal study.