Glaucocalyxin A induces cell cycle arrest and apoptosis via inhibiting NF-κB/p65 signaling pathway in melanoma cells

Interaction of glaucocalyxin a with glutathione and thioredoxin reductase for triple-negative breast cancer treatment

Glaucocalyxin A (GLA) is a bioactive diterpenoid isolated from Rabdosia japonica var. that has been applied for centuries in traditional Chinese medicine. Although GLA exhibits potent anticancer activity against various human cancer cells, its cellular targets remain largely unidentified. We reported here that GLA covalently modifies glutathione and selectively inhibits TrxR activity by primarily targeting the Sec498 residue of the protein. Pharmacologic inhibition of TrxR with GLA results in accumulation of reactive oxygen species, decreased total glutathione and thiols, collapse of the intracellular redox balance, and eventually induction of oxidative stress mediated apoptosis in triple-negative breast cancer cells. Importantly, knockdown of TrxR1 increases the sensitivity cells to GLA. Targeting TrxR by GLA thus discloses a newly identified molecular mechanism underlying the biological activity of GLA, and provides an in-depth insight in understanding the action of GLA in treatment of cancer.

Zebrafish TDP43 positively regulates p65-mediated apoptotic pathway

TAR DNA-binding protein 43 (TDP43) is a multifunctional RNA/DNA binding protein that serves as a hallmark of neurodegeneration in amyotrophic lateral sclerosis (ALS) and is associated with the inflammatory response related to nuclear factor κB (NF-κB) pathway. However, the relationship between TDP43 and NF-κB is not well known. In this study, zebrafish TDP43 (DrTDP43) can be induced by grass carp reovirus (GCRV) or spring viremia of carp virus (SVCV). DrTDP43 enhances the nuclear factor-kappaB (NF-κB) activity and the expression of p65 and TNFα, as well as promotes the phosphorylation of p65 in response to stimulation of GCRV and SVCV. Further assays indicate that DrTDP43 primarily resides in the nucleus and interacts with p65 via its RRM1. DrTDP43 is required for p65 to induce pro-inflammatory cytokine production (IL-6, IL-10, TNFα, IL-1β). It disrupts mitochondrial membrane potential and exacerbates apoptosis via downregulating Bcl2 and upregulating Bax, caspase3, and eIF2α. Moreover, knockdown of TDP43 decreases the content of reactive oxygen species (ROS) and the number of apoptotic cells in zebrafish larvae, which is attributed to the lower lever of p65 phosphorylation and expression of TNFα, Bax and cleaved-caspase3. In a word, these results establish TDP43 as a critical activator of the NF-κB-mediated apoptotic pathway during antiviral responses, which reveals a previously unrecognized host defense mechanism.

Induction of the p21/CDK6 pathway and alteration of the immune microenvironment by the stem cell marker CBX3 in melanoma

BACKGROUND

As one of the stem cell markers, chromobox protein homolog 3 (CBX3) participates in multiple signaling pathways that affect the progression of various tumors. However, the role of CBX3 in melanoma remains unclear, and the mechanisms by which CBX3 may regulate immunotherapy outcome remain largely unknown.

METHODS

We used the Cancer Genome Atlas, Genotype-Tissue Expression portal, and Gene Expression Omnibus database to estimate CBX3 expression and its prognostic effect in melanoma. The role of CBX3 in proliferation and migration of melanoma cells were examined using the CCK8, cloning, wound healing, and transwell assays. The effect of CBX3 on melanoma tumorigenesis was assessed using an in vivo animal model. The role of CBX3 in cell cycle was examined using flow cytometry, and expression levels of cell cycle-related genes and proteins in cells with altered CBX3 levels were analyzed using qPCR and western blotting. The function of CBX3 in the immune microenvironment of melanoma was studied using single-cell RNA sequencing and public databases.

RESULTS

We found that CBX3 was highly expressed in melanoma with poor prognosis. CBX3 promoted the proliferation and migration of melanoma cells in vivo and in vitro. Functional analysis revealed that CBX3 regulates cell cycle, as it accelerated the G1 to S transition, decreased p21 expression, and increased CDK6 expression. Finally, single-cell sequencing and immune-related assays showed that CBX3 is immunogenic and can change the immune microenvironment of melanoma.

CONCLUSIONS

We conclude that the stem cell marker, CBX3 activates the p21/CDK6 pathway and alters the immune microenvironment in melanoma.

Zebrafish FKBP5 facilitates apoptosis and SVCV propagation by suppressing NF-κB signaling pathway

FK506-binding protein 5 (FKBP5), encoded by FKBP5 gene, has been reported as a scaffolding protein in various mammalian pathways related to immunity, inflammation, apoptosis and autophagy. However, the role of FKBP5 in lower vertebrates remains unknown. In this study, we identified zebrafish FKBP5 (DrFKBP5), an ortholog of mammalian FKBP5, which shows high homology with its counterpart in Anabarilius grahami based on amino acid alignment and phylogenetic analysis. DrFKBP5 was found to express ubiquitously across all tested tissues. Its expression were significantly upregulated in eye, intestine, gill, skin, heart, liver and kidney following SVCV treatment. A similar expression pattern was also observed in EPC and ZFIN cells. DrFKBP5 decreased the promoter activitiy of NF-κB and IL-6 rather than IFN I. It also inhibited the expression of inflammatory factor genes such as IL-6, IL-1β and TNF-α. In molecular mechanism, we found that DrFKBP5 interacted with IKKβ (an activator of NF-κB pathway), but not with IKKα or IKKγ, suggesting that DrFKBP5 regulates NF-κB pathway by targeting IKKβ. Then, DrFKBP5 significantly reduced the phosphorylation of IKKβ. Furthermore, it inhibited SVCV-induced nuclear translocation, phosphorylation of p65 and promoted SVCV replication in ZFIN cells. Finally, DrFKBP5 activated the expression of apoptosis-related genes, including BAX, Bcl2, caspase-3 and induced apoptosis under SVCV treatment.

Thioredoxin reductase inhibition and glutathione depletion mediated by glaucocalyxin A promote intracellular disulfide stress in gastric cancer cells

Thioredoxin reductase 1 (TXNRD1) has been identified as one of the promising chemotherapeutic targets in cancer cells. Therefore, a novel TXNRD1 inhibitor could accelerate chemotherapy in clinical anticancer research. In this study, glaucocalyxin A (GlauA), a natural diterpene extracted from Rabdosia japonica var. glaucocalyx, was identified as a novel inhibitor of TXNRD1. We found that GlauA effectively inhibited recombinant TXNRD1 and reduced its activity in gastric cancer cells without affecting the enzyme's expression level. Mechanistically, the selenocysteine residue (U498) of TXNRD1 was irreversibly modified by GlauA through a Michael addition. Additionally, GlauA formed a covalent adduct with glutathione (GSH) and disrupted cellular redox balance by depleting cellular GSH. The inhibition of TXNRD1 and depletion of GSH by GlauA conferred its cytotoxic effects in spheroid culture and Transwell assays in AGS cells. The disulfide stress induced cytotoxicity of GlauA could be mitigated by adding reducing agents, such as DTT and β-ME. Furthermore, the FDA-approval drug auranofin, a TXNRD1 inhibitor, triggered oligomerization of the cytoskeletal protein Talin-1 in AGS cells, indicating that inhibiting TXNRD1 triggered disulfide stress. In conclusion, this study uncovered GlauA as an efficient inhibitor of TXNRD1 and demonstrated the potential of TXNRD1 inhibition as an effective anticancer strategy by disrupting redox homeostasis and inducing disulfide stress.

Potential mechanisms of traditional Chinese medicine in the treatment of liver cirrhosis: a focus on gut microbiota

Cirrhosis, a pathological stage that develops from various chronic liver diseases, is characterized by liver fibrosis, pseudolobular formation, and chronic inflammation. When it progresses to the decompensated phase, the mortality rate of cirrhosis can reach 80%. The role of gut microbiota in the progression of liver diseases has received significant attention. Numerous studies have shown that regulating gut microbiota has significant therapeutic effects on preventing and reversing liver cirrhosis. This article reviewed the mechanisms by which gut microbiota influence liver cirrhosis, explaining the effective therapeutic effects of traditional Chinese medicine. Through multi-directional regulation involving signaling pathways, gut microbiota diversity, and restoration of intestinal barrier function, traditional Chinese medicine has been promising in ameliorating liver cirrhosis, providing treatment options and pharmacological guidance for the occurrence and development of liver cirrhosis.

Glaucocalyxin A delays the progression of OA by inhibiting NF-κB and MAPK signaling pathways

BACKGROUND

Osteoarthritis (OA) is a common degenerative joint condition marked by inflammation and cartilage breakdown. Currently, there is a dearth of treatment medications that can clearly slow the course of OA. Glaucocalyxin A (GLA) is a diterpene chemical identified and extracted from Rabdosia japonica with antithrombotic, anticoagulant, anti-tumor, anti-inflammatory, anti-oxidant, and other pharmacological properties. Previous research has linked inflammation to abnormalities in the homeostasis of the extracellular matrix (ECM). Although GLA has been shown to have anti-inflammatory qualities, its effects on the progression of OA are unknown. As a result, the goal of this study was to see if GLA could slow the course of OA.

METHODS

ATDC5 cells were stimulated by IL-1β to create an inflammatory chondrocyte damage model. Quantitative polymerase chain reaction, Western Blot, high-density culture, and immunofluorescence were used to detect the expression levels of associated gene phenotypes. We also created a mouse model of OA induced by destabilization of the medial meniscus (DMM) instability, and GLA was administered intraperitoneally once every two days for eight weeks. Mice knee specimens were stained with hematoxylin-eosin, Safranin O/fast green, and immunohistochemical, and the Osteoarthritis Research Society International grade system and Mankin's score were used to assess the protective effect of GLA on cartilage.

RESULTS

In vitro and in vivo, we explored the effects and molecular processes of GLA as a therapy for OA. The findings demonstrated that GLA might reduce the expression of associated inflammatory mediators and protect the ECM by inhibiting the NF-κB and MAPK signaling pathways. Animal research revealed that GLA could protect against the DMM-induced OA model mice by stabilizing ECM.

CONCLUSION

Taken together, our findings show that GLA has a protective impact on cartilage throughout OA progression, implying that GLA could be employed as a possible therapeutic agent for OA, thus giving a new therapeutic method for the treatment of OA.

A new amide alkaloid induces the apoptosis of human melanoma A375 cellsviainhibition of the STAT3 signaling pathway

A new amide alkaloid (ZYL-01) can inhibit the activity of A375 cells by inducing cell apoptosisviainhibiting STAT3 signaling.

Novel isatin-based hybrids as potential anti-rheumatoid arthritis drug candidates: Synthesis and biological evaluation

Rheumatoid arthritis (RA) is an autoimmune disease accompanied with serious symptoms, such as joint destruction and chronic synovitis. Though many anti-RA drugs could improve the outcome of RA patients to a certain extent, about 40% inefficient rate, severe side effects, and high costs have become urgent problems. Therefore, exploring new alternative drugs for RA therapy is still an urgent need so far. Isatin is an important structural motif found in numerous biologically active compounds and therapeutic agents. Herein, we aim to synthesize several novel isatin analogues for RA therapy and further explore the mechanism of the most potential anti-RA drug candidate in suppressing the pathological progress of RA in vitro and in vivo. We found that the most therapeutic potential compound, a novel small molecule isatin-honokiol hybrid named CT5-2 inhibited the viability of RA-fibroblast-like synoviocytes (FLSs), an effector cell of synovial hyperplasia in the RA synovial tissue with IC50 ranging from 8.54 to 10.66 μM. In addition, CT5-2 reduced the DNA replication and triggered cell cycle arrest and apoptosis of RA-FLSs. Moreover, differential analyses of RNA-sequencing and the mechanistic studies demonstrated that CDCA7 is a key gene correlated with RA progression, and CT5-2 could inhibit the c-Myc/CDCA7/p65 pathway to regulate CDK1, Bcl-2, and vimentin in RA-FLSs. Furthermore, CT5-2 relieved collagen-induced arthritis (CIA) and reduced the level of CDCA7, CDK1, Bcl-2, and vimentin of synovial tissue in CIA mice. Taken together, the novel small molecule isatin-honokiol hybrid CT5-2 exhibits a potential anti-RA drug candidate that inhibits proliferation and triggers cell cycle arrest and apoptosis of RA-FLSs by regulating the c-Myc/CDCA7/p65 pathway. Our study lays a good foundation for further clinical research and structuralmodification of CT5-2.

The Impact of Oxidative Stress and AKT Pathway on Cancer Cell Functions and Its Application to Natural Products

Oxidative stress and AKT serine-threonine kinase (AKT) are responsible for regulating several cell functions of cancer cells. Several natural products modulate both oxidative stress and AKT for anticancer effects. However, the impact of natural product-modulating oxidative stress and AKT on cell functions lacks systemic understanding. Notably, the contribution of regulating cell functions by AKT downstream effectors is not yet well integrated. This review explores the role of oxidative stress and AKT pathway (AKT/AKT effectors) on ten cell functions, including apoptosis, autophagy, endoplasmic reticulum stress, mitochondrial morphogenesis, ferroptosis, necroptosis, DNA damage response, senescence, migration, and cell-cycle progression. The impact of oxidative stress and AKT are connected to these cell functions through cell function mediators. Moreover, the AKT effectors related to cell functions are integrated. Based on this rationale, natural products with the modulating abilities for oxidative stress and AKT pathway exhibit the potential to regulate these cell functions, but some were rarely reported, particularly for AKT effectors. This review sheds light on understanding the roles of oxidative stress and AKT pathway in regulating cell functions, providing future directions for natural products in cancer treatment.

Regulated cell death (RCD) in cancer: key pathways and targeted therapies

Regulated cell death (RCD), also well-known as programmed cell death (PCD), refers to the form of cell death that can be regulated by a variety of biomacromolecules, which is distinctive from accidental cell death (ACD). Accumulating evidence has revealed that RCD subroutines are the key features of tumorigenesis, which may ultimately lead to the establishment of different potential therapeutic strategies. Hitherto, targeting the subroutines of RCD with pharmacological small-molecule compounds has been emerging as a promising therapeutic avenue, which has rapidly progressed in many types of human cancers. Thus, in this review, we focus on summarizing not only the key apoptotic and autophagy-dependent cell death signaling pathways, but the crucial pathways of other RCD subroutines, including necroptosis, pyroptosis, ferroptosis, parthanatos, entosis, NETosis and lysosome-dependent cell death (LCD) in cancer. Moreover, we further discuss the current situation of several small-molecule compounds targeting the different RCD subroutines to improve cancer treatment, such as single-target, dual or multiple-target small-molecule compounds, drug combinations, and some new emerging therapeutic strategies that would together shed new light on future directions to attack cancer cell vulnerabilities with small-molecule drugs targeting RCD for therapeutic purposes.

Glaucocalyxin A Inhibits the Malignancies of Gastric Cancer Cells by Downregulating MDM2 and RNF6 via MiR-3658 and the SMG1-UPF mRNA Decay Pathway

Gastric cancer (GC) ranks as the most common gastrointestinal cancer and is among the leading causes of cancer death worldwide. Glaucocalyxin A (GLA), an entkauranoid diterpene isolated from Rab-dosia japonica var., possesses various bioactivities. To date, the data on the effect of GLA on GC are still minimal, and the molecular mechanisms remain largely unknown. Herein, we found that GLA could significantly inhibit the proliferation, cell adhesion, and invasion of HGT-1, SNU-1, SNU-6, and NCI-N87 GC cells in a dose-dependent manner. GLA enhanced the apoptosis of the GC cells as evidenced by the increased caspase-3 activity and the elevated levels of cleaved caspase-3 and cleaved PARP in GC cells in the presence of GLA. We then showed that the downregulation of Murine Double Minute Clone 2 (MDM2) and Ring Finger Protein 6 (RNF6) by GLA was implicated in the GLA-induced inhibition of the GC cells. Furthermore, MDM2 and RNF6 were identified as the targets of miR-3658 that was downregulated in the GC cells and upregulated by GLA. Moreover, it was shown that miR-3658 was hypermethylated in the GC cells, and GLA could rescue the expression of miR-3658 via demethylation by abrogating EZH2-mediated epigenetic silencing. In addition to the miR-3658-MDM2/RNF6 regulatory axis, activation of the SMG1-UPF mRNA decay pathway contributed to the downregulation of MDM2 and RNF6 by GLA in the GC cells. The inhibitory effect of GLA on gastric cancer and the expression of MDM2 and RNF6 was also validated in in vivo study. Our findings suggest that has the therapeutic potential for GC by downregulating oncogenes via posttranscriptional regulation.

Glaucocalyxin A induces apoptosis of NSCLC cells by inhibiting the PI3K/Akt/GSK3β pathway

Lung cancer is one of the fastest growing malignancies in morbidity and mortality, and current therapies are in general not sufficiently effective for this deadly disease. This study characterizes the anti-cancer effects of Glaucocalyxin A (GLA) and explores the underlying mechanisms using human non-small cell lung carcinoma (NSCLC) cells. First, our data showed that GLA suppressed the viability of cancer cells, while no effect was observed in the normal bronchial epithelial cell Bease 2B cells. Second, GLA inhibited colony formation, induced apoptosis of cancer cells. Third, GLA down-regulated the expression of B-cell lymphoma-2 (Bcl-2) protein, up-regulated the expression of Bcl2-associated X protein (Bax) , and strengthened cleavage of Caspase-3 and poly ADP-ribose polymerase (PARP). Fourth, GLA also diminished mitochondrial membrane potential and inhibited phosphatidylinositol 3-kinase (PI3K)/Akt/ glycogen synthase kinase-3β (GSK3β) pathway. In addition, injection of GLA (20 mg/kg) every two days significantly inhibited A549 xenograft tumor growth, accompanied by increased apoptosis and decreased proliferation. Together, our study provides evidence that the anticancer effect of GLA in NSCLC is mediated by inducing apoptosis through inhibiting PI3K/Akt/GSK3β pathway and suggests that GLA may be used as a promising natural medicine for NSCLC therapy. This article is protected by copyright. All rights reserved.

The Challenging Melanoma Landscape: From Early Drug Discovery to Clinical Approval

Melanoma is recognized as the most dangerous type of skin cancer, with high mortality and resistance to currently used treatments. To overcome the limitations of the available therapeutic options, the discovery and development of new, more effective, and safer therapies is required. In this review, the different research steps involved in the process of antimelanoma drug evaluation and selection are explored, including information regarding in silico, in vitro, and in vivo experiments, as well as clinical trial phases. Details are given about the most used cell lines and assays to perform both two- and three-dimensional in vitro screening of drug candidates towards melanoma. For in vivo studies, murine models are, undoubtedly, the most widely used for assessing the therapeutic potential of new compounds and to study the underlying mechanisms of action. Here, the main melanoma murine models are described as well as other animal species. A section is dedicated to ongoing clinical studies, demonstrating the wide interest and successful efforts devoted to melanoma therapy, in particular at advanced stages of the disease, and a final section includes some considerations regarding approval for marketing by regulatory agencies. Overall, considerable commitment is being directed to the continuous development of optimized experimental models, important for the understanding of melanoma biology and for the evaluation and validation of novel therapeutic strategies.

Glaucocalyxin A suppresses osteoclastogenesis induced by RANKL and osteoporosis induced by ovariectomy by inhibiting the NF-κB and Akt pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Glaucocalyxin A (GLA), the most abundant active component of the aboveground sections of Rabdosia japonica (Burm. f.) Hara var. glaucocalyx (Maxim.) Hara, possesses various pharmacological activities, such as antioxidant, antithrombosis, anticoagulation, antibacterial, antitumor, anti-inflammatory activities. According to previous studies, inflammation is closely associated with osteoclast differentiation and activity. Although GLA has demonstrated effective anti-inflammatory properties, its effects on osteoclast differentiation remain unclear.

AIM OF THE STUDY

To examine the possible inhibitory effects of GLA and its molecular mechanisms in osteogenesis induced by RANKL as well as ovariectomy (OVX)-induced osteoporosis (OP) in mice.

MATERIALS AND METHODS

Tartrate-resistant acid phosphatase (TRAP) staining, F-actin staining, and a bone resorption pit assay were applied for identifying the effects of GLA on the differentiation of osteoclasts and the function of bone resorption. The mRNA expression of the genes related to osteoclast differentiation was measured by quantitative PCR. Protein expression of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), c-fos and phosphorylation of inhibitor of nuclear factor kappa B (IκBα), protein kinase B (AKT), c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38 in RANKL-induced osteoclasts was determined using western blotting. The effect of GLA on OP was studied using a mouse model of OVX.

RESULTS

At nontoxic concentrations ≤0.5 μM in vitro, GLA suppressed the formation of osteoclasts induced by RANKL with the decreased number and area size of TRAP-positive multinuclear osteoclasts, and the resorption of bone function by reducing F-actin ring number and bone resorption pit areas. It also reduced the expression of the genes specific for osteoclasts, which included genes encoding NFATc1, cathepsin K, c-fos, TRAP, vacuolar-type ATPase d2, and dendritic cell-specific transmembrane protein. Moreover, GLA repressed NF-κB and Akt pathway activation induced by RANKL. Micro-CT analysis of femur samples indicated decreased bone loss and greater trabecular bone density after GLA treatment, which showed that GLA played a protective role by inhibiting bone loss in OVX-induced OP mice in vivo.

CONCLUSIONS

Our study is the first to show that GLA has significant therapeutic potential in OP, which is the disease of osteoclast increase caused by estrogen deficiency.