Circular RNA-encoded oncogenic PIAS1 variant blocks immunogenic ferroptosis by modulating the balance between SUMOylation and phosphorylation of STAT1.

BACKGROUND: The clinical response rate to immune checkpoint blockade (ICB) therapy in melanoma remains low, despite its widespread use. Circular non-coding RNAs (circRNAs) are known to play a crucial role in cancer progression and may be a key factor limiting the effectiveness of ICB treatment. METHODS: The circRNAs that were downregulated after coadministration compared with single administration of PD-1 inhibitor administration were identified through RNA-seq and Ribo-seq, and thus the circPIAS1 (mmu_circ_0015773 in mouse, has_circ_0008378 in human) with high protein coding potential was revealed. Fluorescence in situ hybridization (FISH) assays were conducted to determine the localization of circPIAS1 in human and mouse melanoma cells, as well as its presence in tumor and adjacent tissues of patients. Validation through dual-luciferase reporter assay and LC-MS/MS confirmed the ability of circPIAS1 to encode a novel 108 amino acid polypeptide (circPIAS1-108aa). Specific antisense oligonucleotides (ASOs) targeting the junction site of circPIAS1 were developed to reduce its intracellular levels. Proliferation changes in melanoma cells were assessed using CCK8, EdU, and colony formation assays. The impact of circPIAS1-108aa on the ferroptosis process of melanoma cells was studied through GSH, MDA, and C11-BODIPY staining assays. Western Blot, Immunoprecipitation (IP), and Immunoprecipitation-Mass Spectrometry (IP-MS) techniques were employed to investigate the impact of circPIAS1-108aa on the P-STAT1/SLC7A11/GPX4 signaling pathway, as well as its influence on the balance between STAT1 SUMOylation and phosphorylation. Additionally, a melanoma subcutaneous transplanted tumor mouse model was utilized to examine the combined effect of reducing circPIAS1 levels alongside PD-1 inhibitor. RESULTS: Compared with the group treated with PD-1 inhibitor alone, circPIAS1 was significantly down-regulated in the coadministration group and demonstrated higher protein coding potential. CircPIAS1, primarily localized in the nucleus, was notably upregulated in tumor tissues compared to adjacent tissues, where it plays a crucial role in promoting cancer cell proliferation. This circRNA can encode a unique polypeptide consisting of 108 amino acids, through which it exerts its cancer-promoting function and impedes the effectiveness of ICB therapy. Mechanistically, circPIAS1-108aa hinders STAT1 phosphorylation by recruiting SUMO E3 ligase Ranbp2 to enhance STAT1 SUMOylation, thereby reactivating the transduction of the SLC7A11/GPX4 signaling pathway and restricting the immunogenic ferroptosis induced by IFNγ. Furthermore, the combination of ASO-circPIAS1 with PD-1 inhibitor effectively inhibits melanoma growth and significantly enhances the efficacy of immune drugs in vivo. CONCLUSIONS: Our study uncovers a novel mechanism regarding immune evasion in melanoma driven by a unique 108aa peptide encoded by circPIAS1 in melanoma that dramatically hinders immunogenic ferroptosis triggered by ICB therapy via modulating the balance between SUMOylation and phosphorylation of STAT1. This work reveals circPIAS1-108aa as a critical factor limiting the immunotherapeutic effects in melanoma and propose a promising strategy for improving ICB treatment outcomes.

Pt─O Bond Accelerated Cu0/Cu+ Activity for Boosting Low-Energy Bipolar Hydrogen Production.

To address the imperative challenge of producing hydrogen in a low-energy consumption electrocatalytic system, this study emphasizes the utilization of thermodynamically favorable biomass oxidation for achieving energy-efficient hydrogen generation. This research integrates ultralow PtO2-loaded flower-like nanosheets (denoted as PtO2@Cu2O/Cu FNs) with Cu0/Cu+ pairs and Pt─O bonds, thereby yielding substantial enhancement in both hydrogen evolution reaction (HER, -0.042 VRHE at 10 mA cm-2) and furfural oxidation reaction (FFOR, 0.09 VRHE at 10 mA cm-2). As validated by DFT calculations, the dual built-in electric field (BIEF) is elucidated as the driving force behind the enhanced activities, in which Pt─O bonds expedite the HER, while Cu+/Cu0 promotes low-potential FFOR. By coupling the FFOR and HER together, the resulting bipolar-hydrogen production system requires a low power input (0.5072 kWh per m3) for producing H2. The system can generate bipolar hydrogen and high value-added furoic acid, significantly enhancing hydrogen production efficiency and concurrently mitigating energy consumption.

Withanolides from Physalis angulata var. villosa and the Relative Configurational Revision of Some Known Analogs.

Physalis angulata var. villosa is a plant possessing abundant withanolides, but in-depth research is lacking. In our ongoing study of P. angulata var. villosa, 15 previously undescribed withanolides (1-15), along with 21 known analogs (16-36), were isolated from the whole plant. The structures of the withanolides (1-15) were elucidated based on analysis of their 1D and 2D NMR, HRESIMS, and ECD data. Additionally, the application of γ-gauche effects with the help of ROESY correlations led to the formulation of empirical rules for withanolides with 14-OH/15-OAc to rapidly determine the 14-OH orientations, making it possible to propose configurational revisions of 19 previously reported analogs (1'-19'). Withanolides 1, 4-6, and 10 showed potent cytotoxic activities against three human cancer cell lines (HCT-116, MDA-MB-231, and A549).

Discovery of piperine derivatives as inhibitors of human dihydroorotate dehydrogenase to induce ferroptosis in cancer cells.

Inhibition of human dihydroorotate dehydrogenase (hDHODH) represents a promising strategy for suppressing the proliferation of cancer cells. To identify novel and potent hDHODH inhibitors, a total of 28 piperine derivatives were designed and synthesized. Their cytotoxicities against three human cancer cell lines (NCI-H226, HCT-116, and MDA-MB-231) and hDHODH inhibitory activities were also evaluated. Among them, compound H19, exhibited the strongest inhibitory activities (NCI-H226 IC50 = 0.95 µM, hDHODH IC50 = 0.21 µM). Further pharmacological investigations revealed that H19 exerted anticancer effects by inducing ferroptosis in NCI-H226 cells, with its cytotoxicity being reversed by ferroptosis inhibitors. This was supported by the intracellular growth or decline of ferroptosis markers, including lipid peroxidation, Fe2+, GSH, and 4-HNE. Overall, H19 emerges as a promising hDHODH inhibitor with potential anticancer properties warranting development.

Structurally diverse triterpenoid alkaloids from Buxus rugulosa.

Four new nortriterpenoid alkaloids, namely buxrugulines E-H (1-4), along with five known ones (5-9), were isolated from the twigs and leaves of Buxus rugulosa. Their structures were identified based on extensive NMR data and MS spectroscopic analyses. Our bioassays revealed that compounds 5, 6 and 8 exhibited potent cytotoxicity in vitro against MCF-7 cell lines, with IC50 values ranging from 6.70 to 11.00 µM, respectively.

Structure of the Major G-Quadruplex in the Human EGFR Oncogene Promoter Adopts a Unique Folding Topology with a Distinctive Snap-Back Loop.

EGFR tyrosine kinase inhibitors have made remarkable success in targeted cancer therapy. However, therapeutic resistance inevitably occurred and EGFR-targeting therapy has been demonstrated to have limited efficacy or utility in glioblastoma, colorectal cancer, and hepatocellular carcinoma. Therefore, there is a high demand for the development of new targets to inhibit EGFR signaling. Herein, we found that the EGFR oncogene proximal promoter sequence forms a unique type of snap-back loop containing G-quadruplex (G4), which can be targeted by small molecules. For the first time, we determined the NMR solution structure of this snap-back EGFR-G4, a three-tetrad-core, parallel-stranded G4 with naturally occurring flanking residues at both the 5'-end and 3'-end. The snap-back loop located at the 3'-end region forms a stable capping structure through two stacked G-triads connected by multiple potential hydrogen bonds. Notably, the flanking residues are consistently absent in reported snap-back G4s, raising the question of whether such structures truly exist under in vivo conditions. The resolved EGFR-G4 structure has eliminated the doubt and showed distinct structural features that distinguish it from the previously reported snap-back G4s, which lack the flanking residues. Furthermore, we found that the snap-back EGFR-G4 structure is highly stable and can form on an elongated DNA template to inhibit DNA polymerase. The unprecedented high-resolution EGFR-G4 structure has thus contributed a promising molecular target for developing alternative EGFR signaling inhibitors in cancer therapeutics. Meanwhile, the two stacked triads may provide an attractive site for specific small-molecule targeting.

Meso-Hannokinol inhibits breast cancer bone metastasis via the ROS/JNK/ZEB1 axis.

Distal metastases from breast cancer, especially bone metastases, are extremely common in the late stages of the disease and are associated with a poor prognosis. EMT is a biomarker of the early process of bone metastasis, and MMP-9 and MMP-13 are important osteoclastic activators. Previously, we found that meso-Hannokinol (HA) could significantly inhibit EMT and MMP-9 and MMP-13 expressions in breast cancer cells. On this basis, we further explored the role of HA in breast cancer bone metastasis. In vivo, we established a breast cancer bone metastasis model by intracardially injecting breast cancer cells. Intraperitoneal injections of HA significantly reduced breast cancer cell metastasis to the leg bone in mice and osteolytic lesions caused by breast cancer. In vitro, HA inhibited the migration and invasion of breast cancer cells and suppressed the expressions of EMT, MMP-9, MMP-13, and other osteoclastic activators. HA inhibited EMT and MMP-9 by activating the ROS/JNK pathway as demonstrated by siJNK and SP600125 inhibition of JNK phosphorylation and NAC scavenging of ROS accumulation. Moreover, HA promoted bone formation and inhibited bone resorption in vitro. In conclusion, our findings suggest that HA may be an excellent candidate for treating breast cancer bone metastasis.

Withanolides from Physalin angulata and Their Inhibitory Effects on Nitric Oxide Production.

Six new withanolides, angulasteroidins A-F (1-6), along with twelve known analogs (7-18) were isolated from the whole plants of Physalis angulata. Their structures were elucidated by analysis of 1D and 2D NMR, ECD and IR spectra, HR-ESI-MS data, and ECD calculation. Compounds 1 and 6 were rare 1-10 seco withanolides. Compounds 2-4, 7-9, and 15 exhibited significant inhibitory activity on the production of nitric oxide in the LPS-activated RAW 264.7 mouse macrophage cell lines with IC50 values ranging from 0.23 to 9.06 µM.

Bioactive Dimeric Diterpenoids from Taiwania cryptomerioides (Hayata) and Their Biological Activities.

Taiwania cryptomerioides Hayata is an endangered relict plant belonging to Taxodiaceae, and it is also an endemic plant to China. The decay-resistant of Taiwania timber can provide highly quality wood for building and furniture. Plenty of regenerative of leaves of T. cryptomerioides also has been used as a resource for the discovery of new dimeric diterpenoids. In a search for structurally diverse dimeric diterpenoids and potent bioactive isolates, ten new heterodimeric diterpenoids, taiwaniadducts K-T (1-4, 6, 8-11, and 14), along with five known ones (5, 7, 12, 13, and 15), were isolated from the leaves of T. cryptomerioides. These new compounds were defined by comprehensive spectroscopic analyses, putative biosynthetic pathways, and the values of optical. Biologically, anti-multidrug resistance (MDR) activities of compounds were evaluated. Compounds 4 and 10 exerted a 9.18-fold potentiation effect on bortezmib (BTZ) susceptibility at a tested concentration (20 µM) better than the positive control verapamil. The research of the leaves of T. cryptomerioides not only added the new data to the structural diversity and activities of dimeric diterpenoids but also could provide support for the medical and industrial application of the leaves of this endangered relict plant.

Oxidative Damage Induces a Vacancy G-Quadruplex That Binds Guanine Metabolites: Solution Structure of a cGMP Fill-in Vacancy G-Quadruplex in the Oxidized BLM Gene Promoter.

Guanine (G)-oxidation to 8-oxo-7,8-dihydroguanine (OG) by reactive oxygen species in genomic DNA has been implicated with various human diseases. G-quadruplex (G4)-forming sequences in gene promoters are highly susceptible to G-oxidation, which can subsequently cause gene activation. However, the underlying G4 structural changes that result from OG modifications remain poorly understood. Herein, we investigate the effect of G-oxidation on the BLM gene promoter G4. For the first time, we show that OG can induce a G-vacancy-containing G4 (vG4), which can be filled in and stabilized by guanine metabolites and derivatives. We determined the NMR solution structure of the cGMP-fill-in oxidized BLM promoter vG4. This is the first complex structure of an OG-induced vG4 from a human gene promoter sequence with a filled-in guanine metabolite. The high-resolution structure elucidates the structural features of the specific 5'-end cGMP-fill-in for the OG-induced vG4. Interestingly, the OG is removed from the G-core and becomes part of the 3'-end capping structure. A series of guanine metabolites and derivatives are evaluated for fill-in activity to the oxidation-induced vG4. Significantly, cellular guanine metabolites, such as cGMP and GTP, can bind and stabilize the OG-induced vG4, suggesting their potential regulatory role in response to oxidative damage in physiological and pathological processes. Our work thus provides exciting insights into how oxidative damage and cellular metabolites may work together through a G4-based epigenetic feature for gene regulation. Furthermore, the NMR structure can guide the rational design of small-molecule inhibitors that specifically target the oxidation-induced vG4s.

Diverse polycyclic polyprenylated acylphloroglucinols with anti-neuroinflammatory activity from Hypericum beanii.

A phytochemical investigation on the roots of Hypericum beanii resulted in the isolation of six new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperberlones A-F, along with fourteen known analogues. The structural characterization of these compounds was carried out by analyzing the HRESIMS data, 1D and 2D NMR spectroscopic data, electronic circular dichroism (ECD) calculations, and gauge-independent atomic orbital (GIAO) NMR calculations. Hyperberlone A (1) was a caged PPAP with a rare tricyclo[4.3.1.03,8]decane carbon skeleton. It was deduced to be biosynthetically generated from hyperbeanol C (8) through key Paternò-Büchi reaction, radical cascade cyclizations, and retro-aldol reaction. Compounds 4, 6, 7, 9, 14, and 16 exhibited significant nitric oxide (NO) production inhibitory effects in lipopolysaccharide (LPS)-induced BV-2 microglial cells with IC50 values of 6.11-25.28 µM. Moreover, compound 4 significantly decreased the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in LPS-induced BV-2 microglia, as well as the phosphorylation of JNK.

EGFR mutation mediates resistance to EGFR tyrosine kinase inhibitors in NSCLC: From molecular mechanisms to clinical research.

With the development of precision medicine, molecular targeted therapy has been widely used in the field of cancer, especially in non-small-cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) is a well-recognized and effective target for NSCLC therapies, targeted EGFR therapy with EGFR-tyrosine kinase inhibitors (EGFR-TKIs) has achieved ideal clinical efficacy in recent years. Unfortunately, resistance to EGFR-TKIs inevitably occurs due to various mechanisms after a period of therapy. EGFR mutations, such as T790M and C797S, are the most common mechanism of EGFR-TKI resistance. Here, we discuss the mechanisms of EGFR-TKIs resistance induced by secondary EGFR mutations, highlight the development of targeted drugs to overcome EGFR mutation-mediated resistance, and predict the promising directions for development of novel candidates.

Diverse Polycyclic Polyprenylated Acylphloroglucinol Congeners with Anti-Nonalcoholic Steatohepatitis Activity from Hypericum forrestii.

The new polycyclic polyprenylated acylphloroglucinols, hyperforcinols A-J (1-10), were isolated from the fruits of Hypericum forrestii, together with 30 biogenetic congeners of known structures. The structures of hyperforcinols A-J were determined by HRESIMS and 1D/2D NMR spectroscopic analysis, and their absolute configurations were determined by a combination of the electronic circular dichroism (ECD) exciton chirality method, ECD calculations, and X-ray diffraction analysis. A selection of 25 isolates, possessing seven types of carbon skeletons, were assessed for their in vitro effects against nonalcoholic steatohepatitis (NASH) using a free fatty acid-induced L02 cell model. Compounds 20 and 40 significantly decreased intracellular lipid accumulation. QRT-PCR analyses revealed that compounds 20 and 40 regulate the expression of lipid metabolism-related genes, including CD36, FASN, PPARα, and ACOX1.

Synthesis and biological evaluation of novel withangulatin A derivatives as potential anticancer agents.

Novel withangulatin A (WA) derivatives were synthesized and evaluated for antiproliferative activity against four human cancer cell lines (U2OS, MDA-MB-231, HepG2, and A549). Among these derivatives, 10 exhibited the most potent antiproliferative activity, with an IC50 value of 74.0 nM against the human breast cancer cell line MDA-MB-231 and potency that was 70-fold that of WA (IC50 = 5.22 µM). Moreover, 10 caused G2-phase cell cycle arrest in a concentration-dependent manner and induced the apoptosis of MDA-MB-231 cells by increasing intracellular reactive oxygen species (ROS). Compound 10 showed a high selectivity index (SI = 267.03) for breast cancer MDA-MB-231 cells. These results suggest that 10 is a promising anticancer agent.

Dimeric guaianes from leaves of Xylopia vielana as snail inhibitors identified by high content screening.

The transcriptional repressor Snail trriggers epithelial-mesenchymal transition (EMT), the process allowing cancer cells with invasive and metastasis properties. In this study, we screened medicinal plants for the Snail inhibitory active components by high content screen (HCS) and found that the crude extract of Xylopia vielana leaves showed potential activity. Subsequently, bioassay-guided isolation of the extract of Xylopia vielana was performed to obtain twenty-four dimeric guaianes (1-24), including 16 new analogues (1-5, 8-11, 13-15, 17, 18, 21, and 22). Their structures were elucidated by the comprehensive application of multiple spectroscopic methods. Compounds 1, 11, 12, and 16 were initially identified as the active compounds. Wound healing assay, transwell migration assay and western blot experiments verified that compounds 1 and 12 inhibited the expression of Snail in a concentration-dependent manner, and compound 12 was verified as a potent tumor migration inhibitory agent. This work showed a practical strategy for the discovery of new Snail inhibitors from natural products and provided potential insights for dimeric guaianes as anticancer lead compounds specifically targeting Snail protein.

MS diagnostic model and rapid distinguishing of bioactive limonoids in fruits of Melia toosendan using solid-phase extraction coupled with LC-MS/MS.

INTRODUCTION: Melia toosendan Sieb. et Zucc. has been used as a Chinese folk medicine for roundworm treatment since ancient times. Many diverse limonoids have been isolated from Meliaceae plants, but it remains difficult to isolate and identify other limonoids because of their small natural concentrations. OBJECTIVE: This study was performed to overcome the difficulties associated with fast and accurate identification of limonoids and establish a reliable and sensitive method for the analysis of minor limonoids in M. toosendan fruits. METHODS: An efficient strategy for enrichment, detection, and identification of minor limonoids from M. toosendan fruits using solid-phase extraction with high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (SPE-HPLC-Q-TOF-MS/MS) was developed herein. RESULTS: Characteristic fragmentations and fragmentation ions containing trichilin-, nimbin-, and vilasinin-class limonoid skeletons were initially studied, and characteristic diagnostic ions involved retro Diels-Alder (RDA) reactions or homolytic cleavages, which were used to identify minor limonoids. In total, 13 limonoids, including four new ones, were identified. CONCLUSION: This is the first report on the analysis of M. toosendan fruits to identify limonoids. This novel analysis method may stimulate further research regarding the identification of limonoids in other plant species.

Furan fragment isomerized andirobin-type limonoids from the stem barks of Khaya senegalensis.

A new andirobin-type limonoid with modified furan ring, khaysenelide K (1), together with a known analogue (2), was isolated from the stem barks of Khaya senegalensis. The structure and absolute configuration of 1 were elucidated by a combination of 1D and 2D NMR, HRESIMS, and single-crystal X-ray diffraction using mirror Cu-Kα radiation. Compound 1 showed moderate NO inhibitory activity in LPS-activated RAW 264.7 macrophages with IC50 value of 27.74 ± 0.68 µM.[Formula: see text].

Patulignans A-C, three structurally unique lignans from the leaves of Melicope patulinervia.

(±)-Patulignans A-C (1-3), three unique pairs of lignan enantiomers were isolated from the leaves of Melicope patulinervia. Patulignan A (1) possesses an unprecedented dimethyloxonane moiety in nature, meanwhile patulignans B (2) and C (3) are epimers carrying a novel dimethyl-1,6-dioxaspiro[4.5]decane skeleton. Their structures were established by spectroscopy methods and electronic circular dichroism (ECD) calculations. Compounds 1-3 showed significant inhibitory activity against α-glucosidase.

Cytotoxic Germacranolides from the Whole Plant of Carpesium minus.

Eight new germacranolides, minusolides A-H (1-8), along with two known analogues, 9 and 10, were isolated from the whole plant of Carpesium minus. Their structures were elucidated by spectroscopic analysis. Compounds 1 and 2, and 6 and 9 are two pairs of rare epimers with opposite configurations at C-2 of the 2-methylbutyryloxy group. The absolute configurations were determined by X-ray diffraction studies. Compound 7 exhibited cytotoxic activities against MDA-MB-231, A549, and HCT-116 cells with IC50 values of 6.1 ± 0.2, 8.4 ± 0.6, and 3.7 ± 0.6 µM, respectively. Compound 7 induced the apoptosis of HCT-116 cells via suppression of PARP and promoting cleavage of PARP.

Taxumarienes A-G, seven new α-glucosidase inhibitory taxane-diterpenoids from the leaves of Taxus mairei.

Seven new taxane diterpenoids taxumarienes A-G (1-7) were isolated from the leaves of Taxus mairei, along with seven known analogous (8-14). The structures of the new compounds were elucidated based on the analysis of NMR and MS spectroscopy. All isolates were evaluated for their α-glucosidase inhibitory activities. Among them, taxumarienes A (1) and F (6) showed potent effect with IC50 values of 5.9 ±â€¯1.30 µM and 3.7 ±â€¯0.75 µM, respectively.