Withanolides from dietary tomatillo suppress HT1080 cancer cell growth by targeting mutant IDH1.

Isocitrate dehydrogenase (IDH) is one key rate-limiting enzyme in the tricarboxylic acid cycle, which is related to various cancers. Tomatillo (Physalis ixocarpa), a special tomato, is widely consumed as nutritious vegetable in Mexico, USA, etc. As a rich source for withanolides, the fruits of P. ixocarpa were investigated, leading to the isolation of 11 type-A withanolides including 4 new ones (1 is an artificial withanolide). All these withanolides were evaluated for their inhibition on mutant IDH1 enzyme activity. Among them, physalin F (11) exhibited potent enzyme inhibitory activity and binding affinity with mutant IDH1. It inhibits the proliferation of HT1080 cells by selectively inhibiting the activity of mutant IDH1. Since Ixocarpalactone A, another major type-B withanolide in this plant, could act on another energy metabolism target PHGDH, the presence of different types of withanolides in tomatillo and their synergistic effect could make it a potential antitumor functional food or drug.

Metal-Protein Nanoparticles Facilitate Anti-VSV and H1N1 Viruses Through the Coordinative Actions on Innate Immune Responses and METTL14.

Host defense systems can invade viral infection through immune responses and cellular metabolism. Recently, many studies have shown that cellular metabolism can be reprogrammed through N6 -methyladenosine (m6 A) modifications during viral infection. Among of them, methyltransferase like-14 enzyme (METTL14) plays an important role in m6 A RNA modification, yet its antiviral function still remains unclear. In this work, it is uncovered that metal-protein nanoparticles designated GSTP1-MT3(Fe2+ ) (MPNP) can polarize macrophages toward the M1 phenotype and activate immune responses to induce Interferon-beta (IFN-ß) production in vesicular stomatitis virus (VSV)-infected macrophages. Further investigation elucidates that a high dose of IFN-ß can promote the expression of METTL14, which has a well anti-VSV capacity. Moreover, it is found that other negative-sense single-stranded RNA viruses, such as influenza viruses (H1N1(WSN)), can also be inhibited through either immune responses or METTL14. Collectively, these findings provide insights into the antiviral function of METTL14 and suggest that the manipulation of METTL14 may be a potential strategy to intervene with other negative-sense single-stranded RNA viruses infections.

Ixocarpalactone A from dietary tomatillo inhibits pancreatic cancer growth by targeting PHGDH.

3-Phosphoglycerate dehydrogenase (PHGDH) catalyzes the first rate-limiting step for the synthesis of glucose-derived serine by converting 3-phosphoglycerate (3-PG) to phosphohydroxypyruvate (p-Pyr), which has been reported to associate with tumorigenesis in many cancers. Iox A, a natural withanolide obtained from dietary tomatillo (Physalis ixocarpa), showed significant PHGDH inhibitory activity with an IC50 value of 1.66 ± 0.28 µM, and it was further confirmed to bind directly to PHGDH by the MST assay. Molecular docking demonstrated that Iox A coordinated at the allosteric site of PHGDH, which was consistent with the non-competitive kinetics. Meanwhile, Iox A selectively inhibited the proliferation of high PHGDH-expressing cancer cell lines (SW1990, MCF-7 and HeLa) and showed no obvious cytotoxicities on normal human cells (LO2, L929 and HPDE6-C7). In particular, Iox A showed a dose-dependent proapoptotic activity against SW1990 cells in a micromolar concentration as detected by flow cytometry and western blot analysis. DARTS and siRNA assays further demonstrated that Iox A directly targets at PHGDH to inhibit the proliferation of SW1990 cells. Furthermore, Iox A significantly inhibited the tumor growth in a SW1990 xenograft mouse model with low toxicities, suggesting its potential therapeutic application in pancreatic cancer treatment. Therefore, Iox A was identified as a novel natural PHGDH inhibitor with high targeting and low toxicities for the treatment of pancreatic cancers.