In Vivo Molecular Imaging of the Efficacy of Aminopeptidase N (APN/CD13) Receptor Inhibitor Treatment on Experimental Tumors Using 68Ga-NODAGA-c(NGR) Peptide.

Adrienn Kis,István Kertész,Judit P Szabó,Kata Nóra Enyedi,György Trencsényi,Gábor Mező,Péter Bai,Gábor Méhes,Lívia Beke,Orsolya Matolay,Viktória Arató,Noémi Dénes,Enzo Terreno

doi:10.1155/2021/6642973

Adrienn Kis, István Kertész + Show 11 more

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https://doi.org/10.1155/2021/6642973

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Abstract

Introduction The aminopeptidase N (APN/CD13) receptor plays an important role in the neoangiogenic process and metastatic tumor cell invasion. Clinical and preclinical studies reported that bestatin and actinonin are cytotoxic to APN/CD13-positive tumors and metastases due to their APN/CD13-specific inhibitor properties. Our previous studies have already shown that 68Ga-labeled NGR peptides bind specifically to APN/CD13 expressing tumor cells. The APN/CD13 specificity of 68Ga-NGR radiopharmaceuticals enables the following of the efficacy of antiangiogenic therapy with APN/CD13-specific inhibitors using positron emission tomography (PET). The aim of this in vivo study was to assess the antitumor effect of bestatin and actinonin treatment in subcutaneous transplanted HT1080 and B16-F10 tumor-bearing animal models using 68Ga-NODAGA-c(NGR). Materials and Methods Three days after the inoculation of HT1080 and B16-F10 cells, mice were treated with intraperitoneal injection of bestatin (15 mg/kg) or actinonin (5 mg/kg) for 7 days. On the 5th and 10th day, in vivo PET scans and ex vivo biodistribution studies were performed 90 min after intravenous injection of 5.5 ± 0.2 MBq68Ga-NODAGA-c(NGR). Results Control-untreated HT1080 and B16-F10 tumors were clearly visualized by the APN/CD13-specific 68Ga-NODAGA-c(NGR) radiopharmaceutical. The western blot analysis also confirmed the strong APN/CD13 positivity in the investigated tumors. We found significantly (p ≤ 0.05) lower radiopharmaceutical uptake after bestatin treatment and higher radiotracer accumulation in the actinonin-treated HT1080 tumors. In contrast, significantly lower (p ≤ 0.01) 68Ga-NODAGA-c(NGR) accumulation was observed in both bestatin- and actinonin-treated B16-F10 melanoma tumors compared to the untreated-control tumors. Bestatin inhibited tumor growth and 68Ga-NODAGA-c(NGR) uptake in both tumor models. Conclusion The bestatin treatment is suitable for suppressing the neoangiogenic process and APN/CD13 expression of experimental HT1080 and B16-F10 tumors; furthermore, 68Ga-NODAGA-c(NGR) is an applicable radiotracer for the in vivo monitoring of the efficacy of the APN/CD13 inhibition-based anticancer therapies.

Highlights

The aminopeptidase N (APN/CD13) receptor plays an important role in the neoangiogenic process and metastatic tumor cell invasion
Several studies reported that APN/CD13 is overexpressed in the endothelial cells of tumor vasculature and in several solid tumors, such as melanoma [18, 19], prostate carcinoma [20], lung cancer [21], pancreas adenocarcinoma [22], ovarian cancer [23], breast cancer [13], colon cancer [24], thyroid cancer [25], and fibrosarcomas [26]
After the quantitative analysis of the reconstructed decay-corrected positron emission tomography (PET) images, we found that the SUVmean values of the bestatin-treated tumors (0:02 ± 0:01) were significantly (p ≤ 0:05 and p ≤ 0:01) lower than that of the control-untreated tumors (0:07 ± 0:03) and the actinonintreated tumors (0:08 ± 0:04) five days after HT1080 tumor cell implantation (Figure 1(b))

Summary

Introduction

The aminopeptidase N (APN/CD13) receptor plays an important role in the neoangiogenic process and metastatic tumor cell invasion. The APN/CD13 specificity of 68Ga-NGR radiopharmaceuticals enables the following of the efficacy of antiangiogenic therapy with APN/CD13-specific inhibitors using positron emission tomography (PET) The aim of this in vivo study was to assess the antitumor effect of bestatin and actinonin treatment in subcutaneous transplanted HT1080 and B16-F10 tumor-bearing animal models using 68Ga-NODAGA-c(NGR). The bestatin treatment is suitable for suppressing the neoangiogenic process and APN/CD13 expression of experimental HT1080 and B16-F10 tumors; 68Ga-NODAGA-c(NGR) is an applicable radiotracer for the in vivo monitoring of the efficacy of the APN/CD13 inhibition-based anticancer therapies. Several receptors and molecules (e.g., VEGF, integrins, and APN/CD13) appear in the cell surface, which provide opportunities to detect and treat malignant tumors [9,10,11,12] Among these angiogenic molecules, aminopeptidase N (APN/CD13) showed a strong correlation with tumor-associated neoangiogenesis [13,14,15]. Actinonin—as a peptide deformylase inhibitor—is an effective APN/CD13 inhibitor which has antiproliferative impact on human promyelocytic leukemia, human myeloid leukemia, and signalized antitumor effect on murine leukemia [42, 43]

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