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.

Li-Fang Shen,Jun Fan,Xin Zhao,Shui-Hong Zhou,Zhong-Jie Lu,Min-Li Zhou,Kui Zhao

doi:10.18632/oncotarget.16671

Abstract

PurposeHypoxia-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 MethodsTo 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.Results10 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).ConclusionsSimultaneous 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.

Highlights

Promising therapeutic strategies have been described, the poor overall survival rate of patients with laryngeal carcinoma remains unchanged [1]
We explored whether the expression of Hypoxia-inducible factor 1α (HIF-1α) and glucose transporter-1 (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
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

Summary

Introduction

Promising therapeutic strategies have been described, the poor overall survival rate of patients with laryngeal carcinoma remains unchanged [1]. The underlying mechanisms of radioresistance is still unclear and involves multiple factors including tumor cell proliferation, hypoxia and intrinsic radioresistance [2, 3]. HIF-1α is important factor induced during the adaptive response to hypoxia [5]. HIF-1α regulates multiple aspects of tumorigenesis, including proliferation, differentiation, angiogenesis, metabolism, metastasis, and responses to radiation therapy, making it a key regulator of malignant tumor phenotypes [6, 7]. HIF-1α has been associated with a poor prognosis in laryngeal carcinoma [8]. It has been reported that high expression of HIF and other endogenous hypoxia-related proteins was associated with radioresistance and a worse overall survival rate [5, 9]. HIF-1α has been suggested as a potential therapeutic target to improve radiosensitivity in vitro and in vivo [10, 11]

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Conclusion