[68 Ga]Ga-CXCR4 PET/CT imaging in high-grade glioma for assessment of CXCR4 receptor expression.

PURPOSE: Gliomas account for 75 % of primary malignant CNS tumors. High-grade glioma (CNS WHO grades 3 and 4) have an unfavorable treatment response and poor outcome. CXCR4 is a G protein-coupled receptor that plays an important part in the signaling pathway between cancer cells and tumor microenvironment. CXCR4 overexpression has been shown in a variety of cancers. In this study, we evaluate the potential value of [68Ga]Ga-Pentixafor as a PET/CT CXCR4-probe for in vivo assessment of CXCR4 expression in patients with high-grade glioma and its correlation with tumor grade. MATERIALS AND METHODS: [68Ga]Ga-CXCR4 PET/CT was performed in the prospective single-center study in treatment-naïve biopsy-proven patients with high-grade glioma. The acquired images were analyzed qualitatively and semi-quantitatively. RESULT: A total of 26 patients (mean age: 53.3±14.4 years, 11 women, 15 men) were enrolled. CNS WHO grade 3 pathology was seen in 19 % (5/26) of the sample. The patient-based sensitivity of 68Ga-CXCR4 was 96.2 %. Overall, 28 pathologic lesions were detected, leading to a lesion-based sensitivity of 96.4 %. The median (IQR) SUVmax of grade 4 lesions was substantially greater than the grade 3(3.03(2.5-3.7) vs. 1.51(1.2-1.8), p = 0.0145).). The highest tracer activity of organs -beside bladder as the main excretion reservoir-was in lymphoid tissue of Waldeyer's ring (mean SUVmax: 7.41), and spleen (mean SUVmax: 6.62). CONCLUSION: In conclusion, this new application for [68Ga]Ga-Pentixafor PET tracer exhibits excellent visual and semi-quantitative diagnostic properties. Further studies are warranted.

188Rhenium Treatment Induces DACT2 Expression in Hepatocellular Carcinoma Cells.

Objective: Epigenetic alterations, including any change in DNA methylation pattern, could be the missing link of understanding radiation-induced genomic instability. Dapper, Dishevelled-associated antagonist of ß-catenin homolog 2 (DACT2) is a tumor suppressor gene regulating Wnt/ß-catenin. In hepatocellular carcinoma (HCC), DACT2 is hypermethylated, while methylation status of its promoter regulates the corresponding expression. Radionuclides have been used to reduce proliferation and induce apoptosis in cancerous cells. Epigenetic impact of radionuclides as therapeutic agents for treatment of HCC is still unknown. The aim of this study was to evaluate epigenetic impact of 188Rhenium perrhenate (188ReO4) on HCC cells. Materials and Methods: In this in vitro experimental study, HepG2 and Huh7 cells were treated with 188ReO4, receiving 55 and 73 Mega Becquerel (MBq) exposures, respectively. For cell viability measurement, live/dead staining was carried out 18, 24, and 48 hours post-exposure. mRNA expression level of ß-Catenin, Wnt1, DNMT1, DACT2 and WIF- 1 genes were quantified by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Then, possible regulatory impact of DACT2 upregulation was investigated through evaluating methylation-specific PCR (MS-PCR). Results: Results showed that viability of both cells was reduced after treatment with 188ReO4 at three time points postexposure compared to the control groups. The qRT-PCR results showed that DACT2 mRNA level was significantly increased at 24, and 48 hours post-exposure in HepG2 cells compared to the control group, while, no significant change was observed in Huh7 cells. Methylation pattern of DACT2 promoter remained unchanged in HepG2 and Huh7 cells. Conclusion: Treatment with 188ReO4 reduced viability of HepG2 and Huh7 cells. Although DACT2 expression was increased after 188ReO4 exposure in HepG2 cells, methylation pattern of its promoter remained unchanged. This study assessed impacts of the 188ReO4 ß-irradiation on expression and induction of DACT2 epigenetic aberrations as well as the correlation of this agent with viability of cells.

Rhenium Perrhenate (188ReO4) Induced Apoptosis and Reduced Cancerous Phenotype in Liver Cancer Cells.

Recurrence in hepatocellular carcinoma (HCC) after conventional treatments is a crucial challenge. Despite the promising progress in advanced targeted therapies, HCC is the fourth leading cause of cancer death worldwide. Radionuclide therapy can potentially be a practical targeted approach to address this concern. Rhenium-188 (188Re) is a ß-emitting radionuclide used in the clinic to induce apoptosis and inhibit cell proliferation. Although adherent cell cultures are efficient and reliable, appropriate cell-cell and cell-extracellular matrix (ECM) contact is still lacking. Thus, we herein aimed to assess 188Re as a potential therapeutic component for HCC in 2D and 3D models. The death rate in treated Huh7 and HepG2 lines was significantly higher than in untreated control groups using viability assay. After treatment with 188ReO4, Annexin/PI data indicated considerable apoptosis induction in HepG2 cells after 48 h but not Huh7 cells. Quantitative RT-PCR and western blotting data also showed increased apoptosis in response to 188ReO4 treatment. In Huh7 cells, exposure to an effective dose of 188ReO4 led to cell cycle arrest in the G2 phase. Moreover, colony formation assay confirmed post-exposure growth suppression in Huh7 and HepG2 cells. Then, the immunostaining displayed proliferation inhibition in the 188ReO4-treated cells on 3D scaffolds of liver ECM. The PI3-AKT signaling pathway was activated in 3D culture but not in 2D culture. In nude mice, Huh7 cells treated with an effective dose of 188ReO4 lost their tumor formation ability compared to the control group. These findings suggest that 188ReO4 can be a potential new therapeutic agent against HCC through induction of apoptosis and cell cycle arrest and inhibition of tumor formation. This approach can be effectively combined with antibodies and peptides for more selective and personalized therapy.