Usenamine A induces apoptosis and autophagic cell death of human hepatoma cells via interference with the Myosin-9/actin-dependent cytoskeleton remodeling

Usenamine A: a potential therapeutic agent for rheumatoid arthritis and ankylosing spondylitis through its anti-inflammatory activity

Background

Usenamine A (UA) is a natural compound isolated from the lichen Usnea diffracta, and its therapeutic effects on rheumatic diseases are not well understood. This study aimed to evaluate the potential anti-inflammatory effects of UA and its therapeutic effects on rheumatoid arthritis (RA) and ankylosing spondylitis (AS).

Materials and methods

Molecular docking was performed between the 3D structure of UA and the TNF-TNFR2 complex. Peripheral blood mononuclear cells (PBMCs) from RA and AS patients were treated with UA, and cell viability was measured using the MTS assay and flow cytometry. The in vitro effects of co-culture with UA were determined by measuring inflammatory cytokines, including IFN-γ, IL-17A, and GM-CSF, using flow cytometry and enzyme-linked immunosorbent assay (ELISA). The in vivo effects of UA were evaluated using an arthritis mouse model.

Results

The docking complex of UA bound to the TNF-TNFR2 complex exhibited docking scores of -5.251 kcal/mol and -6.274 kcal/mol, confirming their active sites. UA did not affect cell viability and suppressed the production of inflammatory cytokines in the PBMCs of RA (IFN-γ, IL-17A, and GM-CSF) and AS (GM-CSF) patients. The ELISA also confirmed reduced cytokine levels in the co-culture of UA and PBMCs from RA or AS patients. In the arthritis mouse model, significantly reduced clinical and histological scores were observed in the UA treatment group.

Conclusion

Our findings suggest that UA has potential as a binding target for TNF, suppresses inflammatory cytokines in PBMCs, and exhibits anti-inflammatory effects on arthritis in a mouse model.

Targeting Hepatocellular Carcinoma: Schisandrin A Triggers Mitochondrial Disruption and Ferroptosis

The main focus of this research was to examine SchA's role in the hepatocellular carcinoma (HCC) development. LO2 and Huh7 cell viability were assessed using the MTT assay. The experiments included flow cytometry, colony formation, transwell, wound healing, and immunofluorescence assays to evaluate apoptosis levels, cells colony-forming ability, ROS levels, invasion and migration ability, and mitochondrial membrane potential. Biochemical kits was utilized for checking the ATP, mitochondrial DNA, MDA, GSH, and Fe2+ levels in the Huh7 cells, and western blot for measuring the ferroptosis and AMPK/mTOR related-protein expression levels. The MTT assay demonstrated that SchA significantly reduced the vitality of Huh7 cells ranging from 10 to 50 μM, whereas it exhibited no discernible impact on LO2 cells. Additionally, SchA significantly inhibited colony-forming ability, invasion ability, and migration ability within the concentration range of 10 to 50 μM, with a reduction of 68% in colony formation at 50 μM. SchA also induced apoptosis in a dose-dependent manner. Moreover, SchA was observed to significantly elevate ROS levels dose-dependently, down-regulate mitochondrial membrane potential (JC-1) at 20 and 50 μM, and reduce the levels of ATP and mtDNA dose-dependently. Various concentrations of SchA resulted in a notable elevation in MDA and Fe2+ levels as well as ACSL4 protein expression, accompanied by a reduction in GSH level and the protein expression of GPX4 and SLC7A11. Furthermore, SchA induced the activation of the AMPK/mTOR pathway in Huh7 cells, as evidenced by the increased phosphorylation level of AMPK and decreased phosphorylation level of mTOR. SchA might inhibit the progress of HCC through mitochondrial ferroptosis and dysfunction mediated by AMPK/mTOR pathway.

Recent advances in identifying protein targets of bioactive natural products

Background

Natural products exhibit structural complexity, diversity, and historical therapeutic significance, boasting attractive functions and biological activities that have significantly influenced drug discovery endeavors. The identification of target proteins of active natural compounds is crucial for advancing novel drug innovation. Currently, methods for identifying targets of natural products can be categorized into labeling and label-free approaches based on whether the natural bioactive constituents are modified into active probes. In addition, there is a new avenue for rapidly exploring the targets of natural products based on their innate functions.

Aim

This review aimed to summarize recent advancements in both labeling and label-free approaches to the identification of targets for natural products, as well as the novel target identification method based on the natural functions of natural products.

Methods

We systematically collected relevant articles published in recent years from PubMed, Web of Science, and ScienceDirect, focusing on methods employed for identifying protein targets of bioactive natural products. Furthermore, we systematically summarized the principles, procedures, and successful cases, as well as the advantages and limitations of each method.

Results

Labeling methods allow for the direct labeling of target proteins and the exclusion of indirectly targeted proteins. However, these methods are not suitable for studying post-modified compounds with abolished activity, chemically challenging synthesis, or trace amounts of natural active compounds. Label-free methods can be employed to identify targets of any natural active compounds, including trace amounts and multicomponent mixtures, but their reliability is not as high as labeling methods. The structural complementarity between natural products and their innate receptors significantly increase the opportunities for finding more promising structural analogues of the natural products, and natural products may interact with several structural analogues of receptors in humans.

Conclusion

Each approach presents benefits and drawbacks. In practice, a combination of methods is employed to identify targets of natural products. And natural products' innate functions-based approach is a rapid and selective strategy for target identification. This review provides valuable references for future research in this field, offering insights into techniques and methodologies.

Usenamine A triggers NLRP3/caspase-1/GSDMD-mediated pyroptosis in lung adenocarcinoma by targeting the DDX3X/SQSTM1 axis

BACKGROUND

Usenamine A (C18H17NO6) is a newly developed, natural anticancer drug that reportedly exerts low toxicity. The therapeutic efficacy and underlying mechanisms of usenamine A in lung adenocarcinoma (LUAD) remain poorly understood. We aimed to explore the therapeutic effects and molecular mechanisms through which usenamine A inhibits LUAD tumorigenesis.

METHODS

We used LUAD cell lines H1299 and A549 in the present study. CCK-8 and colony formation assays were performed to analyze cell proliferation. Cell migration, invasion, and apoptosis were evaluated using wound-healing, transwell, and flow cytometric assays, respectively. Levels of reactive oxygen species were measured using a DCFH-DA probe. Inflammatory factors (lactate dehydrogenase, interleukin [IL]-1β, and IL-18) were detected using enzyme-linked immunosorbent assays. Western blotting was performed to determine the expression of NOD-like receptor pyrin 3 (NLRP3)/caspase-1/gasdermin D (GSDMD) pathway-related proteins. Pyroptosis was detected using transmission electron microscopy. The interaction and co-localization of DDX3X and sequestosome 1 (SQSTM1) were identified using co-immunoprecipitation and immunofluorescence assays, respectively. For in vivo assessment, we established a xenograft model to validate the usenamine A-mediated effects and mechanisms of action in LUAD.

RESULTS

Usenamine A inhibited the proliferation, migration, and invasion of LUAD cells. Furthermore, usenamine A induced NLRP3/caspase-1/GSDMD-mediated pyroptosis in LUAD cells. Usenamine A upregulated DDX3X expression to trigger pyroptosis. DDX3X interacted with SQSTM1, which is responsible for inducing pyroptosis. In vivo, usenamine A suppressed LUAD tumorigenesis by triggering NLRP3/caspase-1/GSDMD-mediated pyroptosis via the upregulation of the DDX3X/SQSTM1 axis.

CONCLUSIONS

Usenamine A was found to induce NLRP3/caspase-1/GSDMD-mediated pyroptosis in LUAD by upregulating the DDX3X/SQSTM1 axis.

Interfering with the AKT/mTOR/STAT3/ID1 signaling axis with usenamine A restrains the proliferative and invasive potential of human hepatocellular carcinoma cells

BACKGROUND

Usenamine A, a novel natural compound initially isolated from the lichen Usnea longissima, has exhibited promising efficacy against hepatoma in prior investigation. Nevertheless, the underlying mechanisms responsible for its antihepatoma effects remain unclear. Furthermore, the role of the AKT/mechanistic target of the rapamycin (mTOR)/signal transducer and activator of transcription 3 (STAT3)/inhibitor of differentiation/DNA binding 1 (ID1) signaling axis in hepatocellular carcinoma (HCC), and the potential anti-HCC effects of drugs targeting this pathway are not well understood.

METHODS

CCK-8 assay was used to investigate the effects of usenamine A on the proliferation of human HCC cells. Moreover, the effects of usenamine A on the invasion ability of human HCC cells were evaluated by transwell assay. In addition, expression profiling analysis, quantitative real-time PCR, immunoblotting, immunohistochemistry (IHC) analysis, RNAi, immunoprecipitation, and chromatin immunoprecipitation (ChIP) assay were used to explore the effects of usenamine A on the newly identified AKT/mTOR/STAT3/ID1 signaling axis in human HCC cells.

RESULTS

Usenamine A inhibited the proliferation and invasion of human HCC cell lines (HepG2 and SK-HEP-1). Through the analysis of gene expression profiling, we identified that usenamine A suppressed the expression of ID1 in human HCC cells. Furthermore, immunoprecipitation experiments revealed that usenamine A facilitated the degradation of the ID1 protein via the ubiquitin-proteasome pathway. Moreover, usenamine A inhibited the activity of STAT3 in human HCC cells. ChIP analysis demonstrated that STAT3 positively regulated ID1 expression at the transcriptional level in human HCC cells. The STAT3/ID1 axis played a role in mediating the anti-proliferative and anti-invasive impacts of usenamine A on human HCC cells. Additionally, usenamine A suppressed the STAT3/ID1 axis through AKT/mTOR signaling in human HCC cells.

CONCLUSION

Usenamine A displayed robust anti-HCC potential, partly attributed to its capacity to downregulate the AKT/mTOR/STAT3/ID1 signaling pathway and promote ubiquitin-proteasome-mediated ID1 degradation. Usenamine A has the potential to be developed as a therapeutic agent for HCC cases characterized by abnormal AKT/mTOR/STAT3/ID1 signaling, and targeting the AKT/mTOR/STAT3 signaling pathway may be a viable option for treating patients with HCC exhibiting elevated ID1 expression.