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.

ß-radiating radionuclides in cancer treatment, novel insight into promising approach.

Targeted radionuclide therapy, known as molecular radiotherapy is a novel therapeutic module in cancer medicine. ß-radiating radionuclides have definite impact on target cells via interference in cell cycle and particular signalings that can lead to tumor regression with minimal off-target effects on the surrounding tissues. Radionuclides play a remarkable role not only in apoptosis induction and cell cycle arrest, but also in the amelioration of other characteristics of cancer cells. Recently, application of novel ß-radiating radionuclides in cancer therapy has been emerged as a promising therapeutic modality. Several investigations are ongoing to understand the underlying molecular mechanisms of ß-radiating elements in cancer medicine. Based on the radiation dose, exposure time and type of the ß-radiating element, different results could be achieved in cancer cells. It has been shown that ß-radiating radioisotopes block cancer cell proliferation by inducing apoptosis and cell cycle arrest. However, physical characteristics of the ß-radiating element (half-life, tissue penetration range, and maximum energy) and treatment protocol determine whether tumor cells undergo cell cycle arrest, apoptosis or both and to which extent. In this review, we highlighted novel therapeutic effects of ß-radiating radionuclides on cancer cells, particularly apoptosis induction and cell cycle arrest.

Kinetics of temperature effect on antioxidant activity, phenolic compounds and color of Iranian jujube honey.

In the present study, the Iranian jujube honey was evaluated for its total antioxidant activity by DPPH assay, total phenolic content (TPC) by using the Folin-Ciocalteu reagent, and brown pigment formation (BPF). The kinetics of changes in jujube honey samples heated at various temperatures (45, 55 and 65 °C) over 10 days were studied. Increasing treatment temperature and time caused an increase in all three parameters including, antioxidant activity, BPF and TPC. Increases in BPF and TPC followed zero-order kinetics, and the rise in antioxidant activity varied depending on heating temperatures, following second-order, first-order and zero-order kinetics when samples were heated at 45, 55 and 65 °C, respectively. At 45-65 °C, activation energy values of 68 and 64.7 kJ/mol-1 were obtained for BPF and TPC, respectively. Linear relationships were observed between antioxidant activity and BPF, TPC and antioxidant activity, and BPF and TPC, such that the highest phenol content was related to the darkest honey sample. For all three parameters, heating honey to 65 °C was found to be more effective than heating to 45 or 55 °C.