Circadian control of cisplatin-DNA adduct repair and apoptosis in culture cells.

Cisplatin, a widely prescribed chemotherapeutic agent for treating solid tumors, induces DNA adducts and activates cellular defense mechanisms, including DNA repair, cell cycle checkpoint control, and apoptosis. Considering the circadian rhythmicity displayed by most chemotherapeutic agents and their varying therapeutic efficacy based on treatment timing, our study aimed to investigate whether the circadian clock system influences the DNA damage responses triggered by cisplatin in synchronized cells. We examined the DNA damage responses in circadian-synchronized wild-type mouse embryonic fibroblasts (WT-MEF; clock-proficient cells), cryptochrome1 and 2 double knock-out MEF (CRYDKO; clock-deficient cells), and mouse hepatocarcinoma Hepa1c1c7 cells. Varying the treatment time resulted in a significant difference in the rate of platinum-DNA adduct removal specifically in circadian-synchronized WT-MEF, while CRYDKO did not exhibit such variation. Moreover, diurnal variation in other DNA damage responses, such as cell cycle checkpoint activity indicated by p53 phosphorylation status and apoptosis measured by DNA break frequency, was observed only in circadian-synchronized WT-MEF, not in CRYDKO or mouse hepatocarcinoma Hepa1c1c7 cells. These findings highlight that the DNA damage responses triggered by cisplatin are indeed governed by circadian control exclusively in clock-proficient cells. This outcome bears potential implications for enhancing or devising chronotherapy approaches for cancer patients.

GSK-3ß inhibition by curcumin mitigates amyloidogenesis via TFEB activation and anti-oxidative activity in human neuroblastoma cells.

The translocation of transcription factor EB (TFEB) to the nucleus plays a pivotal role in the regulation of basic cellular processes, such as lysosome biogenesis and autophagy. Autophagy is an intracellular degradation system that delivers cytoplasmic constituents to the lysosome, which is important in maintaining cellular homeostasis during environmental stress. Furthermore, oxidative stress is a critical cause for the progression of neurodegenerative diseases. Curcumin has anti-oxidative and anti-inflammatory activities, and is expected to have potential therapeutic effects in various diseases. In this study, we demonstrated that curcumin regulated TFEB export signalling via inhibition of glycogen synthase kinase-3ß (GSK-3ß); GSK-3ß was inactivated by curcumin, leading to reduced phosphorylation of TFEB. We further showed that H2O2-induced oxidative stress was reduced by curcumin via the Nrf2/HO-1 pathway in human neuroblastoma cells. In addition, we showed that curcumin induced the degradation of amyloidogenic proteins, including amyloid-ß precursor protein and α-synuclein, through the TFEB-autophagy/lysosomal pathway. In conclusion, curcumin regulates autophagy by controlling TFEB through the inhibition of GSK-3ß, and increases antioxidant gene expression in human neuroblastoma cells. These results contribute to the development of novel cellular therapies for neurodegenerative diseases.

Chung Hun Wha Dam Tang attenuates atherosclerosis in apolipoprotein E-deficient mice via the NF-κB pathway.

Chung Hun Wha Dam Tang (CHWDT), a traditional Korean herbal formula, has been used for hundreds of years for alleviating dizziness, phlegm, and inflammation. The inhibitory effects of CHWDT on obesity have been reported. However, the effects of CHWDT in atherosclerosis have not yet been explored. Therefore, the aim of the study was to investigate whether CHWDT could confer protection from oxidative stress and inflammation in a high fat diet (HFD)-induced atherosclerosis model. Atherosclerosis was induced by feeding ApoeE-/- mice with HFD for 6 weeks. To examine the in vivo effects of CHWDT on HFD-induced atherosclerosis, mice on HFD for 6 weeks were orally administrated with CHWDT (400 or 800 mg/kg) every other day for an additional 6 weeks and histological features of aorta were determined by Sudan IV and H&E staining. The mRNA levels of TNF-α, SOD1, SOD2, iNOS or eNOS were determined with RT-PCR analysis or western blot analysis for protein levels. ROS generation was measured by CM-2DCFDA or MitoSox staining using FACS analysis or confocal microscopy. CHWDT decreased the mRNA levels of TNF-α and increased the mRNA levels of SOD1, SOD2 and catalase in both aorta and liver tissues of atherosclerotic mice. CHWDT attenuated TNF-α and iNOS expression in RAW 264.7 cells, U937 cells and HUVECs, and restored eNOS expression in HUVECs. CHWDT decreased H2O2-induced cellular ROS generation in RAW 264.7 cells and U937 cells, and also decreased H2O2-induced mitochondrial ROS generation in RAW 264.7 cells. Furthermore, SOD1, SOD2 and catalase mRNA levels were increased by pre-treatment with CHWDT in H2O2 and LPS-stimulated RAW 264.7 cells, as well as in LPS-treated U937 and HUVECs. CHWDT not only decreased LPS-induced NF-κB p65 phosphorylation but also inhibited the translocation of p65 from the cytosol to the nucleus in RAW 264.7 macrophages. These results suggest that CHWDT exerts inhibitory effects on atherosclerosis-induced oxidative stress and inflammation via the NF-κB pathway.