Analysis of oil synthesis pathway in Cyperus esculentus tubers and identification of oleosin and caleosin genes.

The tubers of the widely distributed Cyperus esculentus are rich in oil, and therefore, the plant is considered to have a high utilization value in the vegetable oil industry. Oleosins and caleosins are lipid-associated proteins found in oil bodies of seeds; however oleosins and caleosins genes have not been identified in C. esculentus. In this study, we performed transcriptome sequencing and lipid metabolome analysis of C. esculentus tubers at four developmental stages to obtain the information on their genetic profile, expression trends, and metabolites in oil accumulation pathways. Overall, 120,881 non-redundant unigenes and 255 lipids were detected; 18 genes belonged to the acetyl-CoA carboxylase (ACC), malonyl-CoA:ACP transacylase (MCAT), ß-ketoacyl-ACP synthase (KAS), and fatty acyl-ACP thioesterase (FAT) gene families involved in fatty acid biosynthesis, and 16 genes belonged to the glycerol-3-phosphate acyltransferase (GPAT), diacylglycerol acyltransferase 3 (DGAT3), phospholipid:diacylglycerol acyltransferase (PDAT), FAD2, and lysophosphatidic acid acyltransferase (LPAAT) gene families playing important roles in triacylglycerol synthesis. We also identified 9 oleosin- and 21 caleosin-encoding genes in C. esculentus tubers. These results provide detailed information on the C. esculentus transcriptional and metabolic profiles, which can be used as reference for the development of strategies to increase oil content in C. esculentus tubers.

Discovery of First-In-Class Potent and Selective Tropomyosin Receptor Kinase Degraders.

We report compounds 5 (CG416) and 6 (CG428) as two first-in-class tropomyosin receptor kinase (TRK) degraders that target the intracellular kinase domain of TRK. Degraders 5 and 6 reduced levels of the tropomyosin 3 (TPM3)-TRKA fusion protein in KM12 colorectal carcinoma cells and inhibited downstream PLCγ1 signaling at sub-nanomolar concentrations. Both degraders also degraded human wild-type TRKA with similar potency. Interestingly, both degraders, especially 6, showed selectivity for the degradation of endogenous TPM3-TRKA over ectopically expressed ATP/GTP binding protein-like 4 (AGBL4)-TRKB or ETS variant transcription factor 6 (ETV6)-TRKC fusion proteins in KM12 cells. Global proteomic profiling assays demonstrated that 5 is highly selective for the intended target. TPM3-TRKA protein degradation induced by 5 and 6 was further confirmed to be mediated through cereblon and the ubiquitin-proteasome system. Compared with the parental TRK kinase inhibitor, both degraders exhibited higher potency for inhibiting growth of KM12 cells. Moreover, both 5 and 6 showed good plasma exposure levels in mice. Therefore, 5 and 6 are valuable chemical tool compounds for investigating the in vivo function of TRK fusion during tumorigenesis. Our study also paves the way for pharmacological degradation of TRK.

Discovery of Selective Small Molecule Degraders of BRAF-V600E.

BRAF is among the most frequently mutated oncogenes in human cancers. Multiple small molecule BRAF kinase inhibitors have been approved for treating melanoma carrying BRAF-V600 mutations. However, the benefits of BRAF kinase inhibitors are generally short-lived. Small molecule-mediated targeted protein degradation has recently emerged as a novel pharmaceutical strategy to remove disease proteins through hijacking the cellular ubiquitin proteasome system (UPS). In this study, we developed thalidomide-based heterobifunctional compounds that induced selective degradation of BRAF-V600E, but not the wild-type BRAF. Downregulation of BRAF-V600E suppressed the MEK/ERK kinase cascade in melanoma cells and impaired cell growth in culture. Abolishing the interaction between degraders and cereblon or blocking the UPS significantly impaired the activities of these degraders, validating a mechanistic role of UPS in mediating targeted degradation of BRAF-V600E. These findings highlight a new approach to modulate the functions of oncogenic BRAF mutants and provide a framework to treat BRAF-dependent human cancers.

Peroxiredoxin V Inhibits Emodin-induced Gastric Cancer Cell Apoptosis via the ROS/Bcl2 Pathway.

BACKGROUND/AIM: Peroxiredoxin (Prx) protein family is aberrantly expressed in various cancers including gastric cancer. Among the six family members, Prx V has been known as an antioxidant enzyme which scavenges intracellular reactive oxygen species (ROS) and modulates cellular apoptosis. This study aimed at investigating the role of Prx V in apoptosis of gastric cancer cells. MATERIALS AND METHODS: Stably constructed Prx V knockdown, over-expression and mock AGS cells (a human gastric adenocarcinoma cell line) were used to study the effect of Prx V on emodin-induced apoptosis by western blotting, cell viability, apoptosis and ROS detection assays. RESULTS: Overexpression of Prx V significantly decreased emodin-induced cellular apoptosis and ROS levels compared to Mock and Prx V knockdown AGS cells. Also, overexpression of Prx V down-regulated the expression of pro-apoptotic proteins, Bad and cleaved PARP, and increased the expression of anti-apoptotic protein, Bcl2. CONCLUSION: Prx V suppresses AGS cell apoptosis via scavenging intracellular ROS and modulating apoptosis-related markers.