1. Theasaponin E1 Inhibits Platinum-Resistant Ovarian Cancer Cells through Activating Apoptosis and Suppressing Angiogenesis
Bo Li, Tuantuan Tong, Ning Ren, Gary O Rankin, Yon Rojanasakul, Youying Tu, Yi Charlie Chen Molecules. 2021 Mar 17;26(6):1681. doi: 10.3390/molecules26061681.
Novel therapeutic strategies for ovarian cancer treatment are in critical need due to the chemoresistance and adverse side effects of platinum-based chemotherapy. Theasaponin E1 (TSE1) is an oleanane-type saponin from Camellia sinensis seeds. Its apoptosis-inducing, cell cycle arresting and antiangiogenesis activities against platinum-resistant ovarian cancer cells were elucidated in vitro and using the chicken chorioallantoic membrane (CAM) assay. The results showed that TSE1 had more potent cell growth inhibitory effects on ovarian cancer OVCAR-3 and A2780/CP70 cells than cisplatin and was lower in cytotoxicity to normal ovarian IOSE-364 cells. TSE1 significantly induced OVCAR-3 cell apoptosis via the intrinsic and extrinsic apoptotic pathways, slightly arresting cell cycle at the G2/M phase, and obviously inhibited OVCAR-3 cell migration and angiogenesis with reducing the protein secretion and expression of vascular endothelial growth factor (VEGF). Western bolt assay showed that Serine/threonine Kinase (Akt) signaling related proteins including Ataxia telangiectasia mutated kinase (ATM), Phosphatase and tensin homolog (PTEN), Akt, Mammalian target of rapamycin (mTOR), Ribosome S6 protein kinase (p70S6K) and e IF4E-binding protein 1(4E-BP1) were regulated, and Hypoxia inducible factor-1α (HIF-1α) protein expression was decreased by TSE1 in OVCAR-3 cells. Moreover, TSE1 treatment potently downregulated protein expression of the Notch ligands including Delta-like protein 4 (Dll4) and Jagged1, and reduced the protein level of the intracellular domain (NICD) of Notch1. Combination treatment of TSE1 with the Notch1 signaling inhibitor tert-butyl (2S)-2-[[(2S)-2-[[2-(3,5-difluorophenyl)acetyl]amino]propanoyl]amino]-2-phenylacetate (DAPT), or the Akt signaling inhibitor wortmannin, showed a stronger inhibition toward HIF-1α activation compared with single compound treatment. Taken together, TSE1 might be a potential candidate compound for improving platinum-resistant ovarian cancer treatment via Dll4/Jagged1-Notch1-Akt-HIF-1α axis.
2. Solid-phase synthesis of O-mannosylated peptides: two strategies compared
D M Andrews, P W Seale Int J Pept Protein Res. 1993 Aug;42(2):165-70. doi: 10.1111/j.1399-3011.1993.tb00493.x.
A comparison of the O-glycosylation of resin-bound assembled peptides with the incorporation of glycosylated amino acids using established chemistry is presented. Fmoc/tert-butyl-based protecting groups were used for the peptidic moieties in conjunction with acetyl sugar protection. Koenigs-Knorr glycosylations were carried out using protected bromomannose derivatives, the acceptor being threonine or serine, either in solution or within a resin-bound peptide. The characterisation of microgram quantities of glycopeptides by the use of glycosidases in combination with mass spectrometry is also described.
3. Honokiol protects hepatocytes from oxidative injury through mitochondrial deacetylase SIRT3
Jing-Xin Liu, Sheng-Nan Shen, Qiang Tong, Yi-Tao Wang, Li-Gen Lin Eur J Pharmacol. 2018 Sep 5;834:176-187. doi: 10.1016/j.ejphar.2018.07.036. Epub 2018 Jul 20.
Oxidative stress contributes to the initiation and progression of liver damage. SIRT3 is a member of nicotinamide adenine dinucleotide-dependent deacetylases that plays a key role in anti-oxidative defense and mitochondrial function in the liver. Honokiol is a natural lignan from the plants of Magnolia genus that exhibits potent anti-oxidative property. This study aims to evaluate the hepatoprotective potential of honokiol against oxidative injury in tert-butyl hydroperoxide (t-BHP)-injured AML12 hepatocytes in vitro and carbon tetrachloride (CCl4)-stimulated liver damaged mice in vivo and to determine whether or not this effect occurs by activating SIRT3. The results showed honokiol protects t-BHP-injured AML12 hepatocytes and CCl4-stimulated liver damage in mice by activating SIRT3. Honokiol reduces the acetylation level of superoxide dismutase 2 to enhance its anti-oxidative capacity, which decreases reactive oxygen species accumulation in AML12 cells. Honokiol increases the deacetylated peroxisome proliferator-activated receptor γ coactivator 1-α level to promote mitochondrial biogenesis. Moreover, honokiol attenuates t-BHP induced mitochondrial fragmentation through Ku70-dynamin-related protein 1 axis. These results suggest that honokiol can ameliorate oxidative damage in hepatocytes by activating SIRT3, which might be a potential therapeutic agent for liver oxidative injury.
