Celastrol elicits antitumor effects by inhibiting the STAT3 pathway through ROS accumulation in non-small cell lung cancer

The anti-cancer mechanism of Celastrol by targeting JAK2/STAT3 signaling pathway in gastric and ovarian cancer

BACKGROUND

Celastrol is a natural triterpene exhibiting significant and extensive antitumor activity in a wide range of cancer. Due to unfavorable toxicity profile and undefined mechanism, Celastrol's application in clinical cancer therapy remains limited. Herein, we elucidate the pharmacological mechanism of Celastrol's anticancer effects, with a focus on STAT3 signaling pathway in cancers with high incidence of metastasis.

METHODS

The safety profile of Celastrol were assessed in mice. In vitro analysis was performed in gastric cancer and ovarian cancer to assess the cytotoxicity, induction of reactive oxygen species (ROS) of Celastrol using STAT3 knockout cancer cells. Effects of Celastrol on STAT3 activation and transcription activity, JAK2/STAT3 signaling protein expression were assessed. Additionally, proteomic contrastive analysis was performed to explore the molecular association of Celastrol with STAT3 deletion in cancer cells.

RESULTS

Celastrol has no obvious toxic effect at 1.5 mg/kg/day in a 15 days' administration. Celastrol inhibits tumor growth and increases ROS in a STAT3 dependent manner in gastric and ovarian cancer celllines. On molecular level, it downregulates IL-6 level and inhibits the JAK2/STAT3 signaling pathway by suppressing STAT3' activation and transcription activity. Proteomic contrastive analysis suggests a similar cellular mechanism of action between Celastrol and STAT3 deletion on regulating cancer progression pathways related to migration and invasion.

CONCLUSION

Our research elucidates the anti-cancer mechanism of Celastrol through targeting the JAK2/STAT3 signaling pathway in cancer with high incidence of metastasis. This study provides a solid theoretical basis for the application of Celastrol in cancer therapy.

NFS1 inhibits ferroptosis in gastric cancer by regulating the STAT3 pathway

Cysteine desulfurase (NFS1) is highly expressed in a variety of tumors, which is closely related to ferroptosis of tumor cells and affects prognosis. The relationship between NFS1 and the development of gastric cancer (GC) remains unknown. Here we showed that NFS1 expression was significantly higher in GC tissues compared to adjacent normal tissues. Patients with high expression of NFS1 in GC tissues had a lower overall survival rate than those with low expression. NFS1 was highly expressed in cultured GC cells compared to normal gastric cells. Knockdown of NFS1 expression reduced the viability, migration and invasion of GC cells. In cultured GC cells, NFS1 deficiency promoted ferroptosis. Mechanistically, NFS1 inhibited ferroptosis by upregulating the signal transduction and activator of transcription 3 (STAT3) signaling pathway in cultured GC cells. NFS1 knockdown using siRNA inhibited the STAT3 pathway, reduced the expression of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), and elevated intracellular levels of reactive oxygen species (ROS), ferrous ion (Fe2+), and malondialdehyde (MDA) in cultured GC cells. A specific STAT3 activator significantly reversed the inhibitory effect of NFS1 deficiency on ferroptosis in cultured GC cells. These in vitro results were further confirmed by experiments in vivo using a mouse xenograft tumor model. Collectively, THESE RESULTS INDICATE THAT NFS1 is overexpressed in human GC tissues and correlated with prognosis. NFS1 inhibits ferroptosis by activating the STAT3 pathway in GC cells. These results suggest that NFS1 may be a potential prognostic biomarker and therapeutic target to treat GC.

Discovery of cinnamylaldehyde-derived mono-carbonyl curcumin analogs as anti-gastric cancer agents via suppression of STAT3 and AKT pathway

The structural modification of curcumin has always been a hotspot in drug development. In this paper, a class of cinnamylaldehyde-derived mono-carbonyl curcumin analogs (MCAs) with 7-carbon-links were designed and synthesized and their anticancer properties were evaluated. Through screening anti-gastric cancer activity of these compounds, H1 exhibited the strongest cytotoxic activity by inhibiting cell viability and colony formation, inducing cell cycle G2/M phase arrest in vitro (SGC-7901 and AGS gastric cancer cells). Moreover, the SGC-7901 subcutaneous tumor-bearing mice studies revealed that H1 significantly inhibited the tumor growth of gastric cancer. We explored the possible potential targets of H1 through network pharmacology. Mechanistically, our results demonstrated that H1 showed potential anti-gastric cancer activity through suppression of the STAT3 and AKT signaling pathway in vitro and in vivo, which was validated by molecular docking. Overall, our results indicate the potential of H1 as a potent chemotherapeutic drug against gastric cancer.

Identification of ATAD3A as a key regulator in non-small cell lung cancer by promoting STAT3-induced cell proliferation and tumor angiogenesis

Malignant proliferation and abundant angiogenesis are major causes of lung adenocarcinoma (LUAD) with high morbidity and mortality. Therefore, the exploration of the key regulatory mechanisms of malignant proliferation and angiogenesis in LUAD provides an opportunity for the development of targeted precision therapy. In this study, we found that the high expression of ATPase family AAA domain-containing protein 3A (ATAD3A) in LUAD was positively associated with the poor survival of patients, while its high expression was positively associated with the angiogenesis of LUAD. Further knockdown of ATAD3A in LUAD significantly inhibited cell proliferation and suppressed expression of vascular endothelial growth factor A, FGF-2, ANG-1, and TGF-β. The opposite effect was observed with ATAD3A overexpression. Furthermore, ATAD3A knockdown significantly inhibited tumor growth and angiogenesis in an in vivo subcutaneous xenograft tumor model. Mechanistic studies suggest that ATAD3A may promote signal transducer and activator of transcription 3 activation, a key signal regulating lung cancer cell proliferation and transcriptional secretion of proangiogenic factors. Therefore, targeted inhibition of ATAD3A may be an effective strategy for LUAD therapy, and ATAD3A may be a potential biomarker for predicting malignant progression.

Mebendazole induces apoptosis and inhibits migration via the reactive oxygen species-mediated STAT3 signaling downregulation in non-small cell lung cancer

Background

The incidence and mortality of non-small cell lung cancer (NSCLC) are extremely high. Previous research has confirmed that the signal transducer and activator of the transcription 3 (STAT3) protein critically participate in the tumorigenesis of NSCLC. Mebendazole (MBZ) has exerts a larger number of pharmacological activities and has anticancer effects in lung cancer, but its mechanism of action remains unclear. This study thus aimed to clarify the impacts of MBZ on NSCLC cell.

Methods

Cell proliferation, migration, and apoptosis were investigated via cell counting kit 8 (CCK-8) assay, Transwell assay, colony formation assay, wound-healing assay, and flow cytometry. Reactive oxygen species (ROS) were detected with a multifunctional microplate reader. Markers of cell migration and apoptosis were detected with Western blotting. The transcriptional activity of STAT3 was detected via luciferase assay. ROS scavenger N-acetylcysteine (NAC) was used to determine the effect of MBZ on NSCLC via ROS-regulated STAT3 inactivation and apoptosis. A xenograft model was constructed in vivo to investigate the role of MBZ in NSCLC tumor growth.

Results

The findings demonstrated that MBZ inhibited NSCLC cell proliferation and migration while promoting apoptosis through triggering ROS generation. In addition, the Janus kinase 2 (JAK2)-STAT3 signaling pathway was abrogated with the treatment of MBZ. NAC could distinctly weaken MBZ-induced apoptosis and STAT3 inactivation. Moreover, MBZ inhibited the tumor growth of NSCLC in vivo.

Conclusions

In summary, MBZ inhibited NSCLC cell viability and migration by inducing cell apoptosis via the ROS-JAK2-STAT3 signaling pathway. These data provide a theoretical basis for the use of MBZ in treating NSCLC.

Terpenoid-Mediated Targeting of STAT3 Signaling in Cancer: An Overview of Preclinical Studies

Cancer has become one of the most multifaceted and widespread illnesses affecting human health, causing substantial mortality at an alarming rate. After cardiovascular problems, the condition has a high occurrence rate and ranks second in terms of mortality. The development of new drugs has been facilitated by increased research and a deeper understanding of the mechanisms behind the emergence and advancement of the disease. Numerous preclinical and clinical studies have repeatedly demonstrated the protective effects of natural terpenoids against a range of malignancies. Numerous potential bioactive terpenoids have been investigated in natural sources for their chemopreventive and chemoprotective properties. In practically all body cells, the signaling molecule referred to as signal transducer and activator of transcription 3 (STAT3) is widely expressed. Numerous studies have demonstrated that STAT3 regulates its downstream target genes, including Bcl-2, Bcl-xL, cyclin D1, c-Myc, and survivin, to promote the growth of cells, differentiation, cell cycle progression, angiogenesis, and immune suppression in addition to chemotherapy resistance. Researchers viewed STAT3 as a primary target for cancer therapy because of its crucial involvement in cancer formation. This therapy primarily focuses on directly and indirectly preventing the expression of STAT3 in tumor cells. By explicitly targeting STAT3 in both in vitro and in vivo settings, it has been possible to explain the protective effect of terpenoids against malignant cells. In this study, we provide a complete overview of STAT3 signal transduction processes, the involvement of STAT3 in carcinogenesis, and mechanisms related to STAT3 persistent activation. The article also thoroughly summarizes the inhibition of STAT3 signaling by certain terpenoid phytochemicals, which have demonstrated strong efficacy in several preclinical cancer models.

Serratia marcescens induces apoptosis in Diaphorina citri gut cells via reactive oxygen species-mediated oxidative stress

BACKGROUND

Asian citrus psyllid, Diaphorina citri, is a notorious pest in the citrus industry because it transmits Candidatus Liberibacter asiaticus, which causes an uncurable, devastating disease in citrus worldwide. Serratia marcescens is widely distributed in various environments that exhibits toxic effects to many insects. To develop strategies for enhancing the efficiency of pathogen-induced host mortality, a better understanding of the toxicity mechanism of Serratia marcescens on Diaphorina citri is critical.

RESULTS

Serratia marcescens KH-001 successfully colonized Diaphorina citri gut by feeding artificial diets, resulting in the damage of cells including nucleus, mitochondria, vesicles, and microvilli. Oral ingestion of Serratia marcescens KH-001 strongly induced apoptosis in gut cells by enhancing levels of Cyt c, p53 and caspase-1 and decreasing levels of inhibitors of apoptosis (IAP) and Bax inhibitor-1 (BI-1). The expression of dual oxidase (Duox) and nitric oxide synthase (Nos) was up-regulated by Serratia marcescens KH-001, which increased hydrogen peroxide (H2 O2 ) levels in the gut. Injection of abdomen of Diaphorina citri with H2 O2 accelerated the death of the adults and induced apoptosis in the gut cells by activating Cyt c, p53 and caspase-1 and suppressing IAP and BI-1. Pretreatment of infected Diaphorina citri with vitamin c (Vc) increased the adult survival and diminished the apoptosis-inducing effect.

CONCLUSIONS

The colonization of Serratia marcescens KH-001 in the guts of Diaphorina citri increased H2 O2 accumulation, leading to severe changes and apoptosis in intestinal cells, which enhanced a higher mortality level of D. citr. This study identifies the underlying virulence mechanism of Serratia marcescens KH-001 on Diaphorina citri that contributes to a widespread application in the integrated management of citrus psyllid. © 2023 Society of Chemical Industry.

Celastrol, which targets IL-2/CD25 binding inhibition, induces T cell-mediated antitumor activity in melanoma

Interleukin-2 (IL-2) induces contrasting immune responses depending on its binding receptor subunit; thus, selective receptor binding is considered a key challenge in cancer therapeutic strategies. In this study, we aimed to investigate the inhibition of IL-2 action and antitumor activity of celastrol (CEL), a compound identified in a screen for IL-2/CD25 binding inhibitors, and to elucidate the underlying role of CEL in immune cells. We found that CEL selectively impairs the binding of IL-2 and CD25 and directly binds to IL-2 but not to CD25. CEL significantly suppressed the proliferation and signaling of IL-2-dependent murine T cells and interfered with IL-2-responsive STAT5 phosphorylation in IL-2 reporter cells and human PBMCs. After confirming the impact of CEL on IL-2, we evaluated its antitumor activity in C57BL/6 mice bearing B16F10 tumors and found that CEL significantly inhibited tumor growth by increasing CD8+ T cells. We also found that CEL did not inhibit tumor growth in T cell-deficient BALB/c nude mice, suggesting that its activity was mediated by the T-cell response. Moreover, combination therapy with low-dose CEL and a TNFR2 antagonist synergistically improved the therapeutic efficacy of the individual monotherapies by increasing the ratio of intratumoral CD8/Treg cells and suppressing Foxp3 expression. These findings suggest that CEL, which inhibits CD25 binding by targeting IL-2, exerts antitumor activity by mediating the T-cell response and could be a promising candidate for combination therapy in cancer immunotherapy against melanoma.

Celastrol induces premature ovarian insufficiency by inducing apoptosis in granulosa cells

Celastrol, a natural compound purified from the Chinese herb Tripterygium wilfordii Hook. f., has excellent pharmacological activity for the treatment of various diseases. Assessing the safety of its use is essential for its development into a clinical medicine. However, research assessing its toxicity on the female reproductive system has never been reported. In this study, the ovarian toxicity of celastrol and its underlying mechanism were investigated. We found that celastrol induced premature ovarian insufficiency and apoptosis in granulosa cells. Activity-based protein profiling results showed that high mobility group box 1 was a candidate target protein of celastrol. Celastrol directly bound to Cys106 of high mobility group box 1. Knocking down high mobility group box 1 induced apoptosis of granulosa cells, while overexpression of this gene reversed celastrol-induced apoptosis. Celastrol treatment upregulated p21 transcription, but overexpression of high mobility group box 1 reversed this upregulation. Thus, Celastrol induces premature ovarian insufficiency and apoptosis in granulosa cells by directly binding to high mobility group box 1 and interfering with its biological function to regulate p21 transcription. This study provides valuable information for assessing the safety of the clinical application of celastrol on female patients.

MIOX inhibits autophagy to regulate the ROS -driven inhibition of STAT3/c-Myc-mediated epithelial-mesenchymal transition in clear cell renal cell carcinoma

The specific mechanism of clear cell renal cell carcinoma (ccRCC) progression, a pathological type that accounts for the highest proportion of RCC, remains unclear. In this study, bioinformatics analysis of scRNA-seq dataset in ccRCC revealed that MIOX was a gene specifically down-regulated in tumor epithelial cells of ccRCC. Analysis of the TCGA database further validated the association between decreased MIOX mRNA levels and ccRCC malignant phenotype and poor prognosis. Immunohistochemistry indicated the down-regulation of MIOX in ccRCC tissues compared to paired adjacent renal tissues, with further down-regulation of MIOX in the primary tumors of patients with primary metastasis compared to those without metastasis. Also, patients with low expression of MIOX showed shorter metastasis-free survival (MFS) compared to those with high MIOX expression. In vitro results showed that overexpression of MIOX in ccRCC cells inhibited the proliferation, migration and invasion and promoted apoptosis. Mechanistically, up-regulation of MIOX inhibited autophagy to elevate the levels of ROS, and thus suppressed STAT3/c-Myc-mediated epithelial-mesenchymal transition in ccRCC cells. In vivo data further confirmed that increased MIOX expression suppressed the growth and proliferation of RCC cells and reduced the ability of RCC cells to form metastases in the lung. This study demonstrates that MIOX is an important regulatory molecule of ccRCC, which is conducive to understanding the potential molecular mechanism of ccRCC progression.

Piperlongumine is a ligand for the orphan nuclear receptor 4A1 (NR4A1)

Piperlongumine and derivatives are being developed as anticancer agents which act primarily as inducers of reactive oxygen species (ROS) in cancer cell lines. Many of the anticancer activities of piperlongumine resemble those observed for bis-indole derived compounds that bind the orphan nuclear receptor 4A1 (NR4A1) and act as inverse receptor agonists to inhibit NR4A1-regulated pro-oncogenic pathways and genes. In this study we show that like other NR4A1 inverse agonists piperlongumine inhibited RKO, SW480 and HCT116 colon cancer cell growth migration and invasion and induced apoptosis. Piperlongumine also downregulated the pro-reductant isocitrate dehydrogenase 1 (IDH1) and thioredoxin domain-containing 5 (TXNDC5) gene products resulting in the induction of ROS as previously observed for other inverse NR4A1 agonists. ROS also induced sestrin2 and this resulted in activation of AMPK phosphorylation and inhibition of mTOR pathway signaling. It has previously been reported that these pathways/genes are also regulated by inverse NR4A1 agonists or by knockdown of NR4A1. We also observed that piperlongumine directly bound NR4A1, inhibited NR4A1-dependent transactivation and interactions of the NR4A1/Sp1 complex bound to the GC-rich promoter of the NR4A1-regulated G9a gene.