T52 attenuates oncogenic STAT3 signaling and suppresses osteosarcoma

Przewaquinone A, as a natural STAT3 inhibitor, suppresses the growth of melanoma cells and induces autophagy

BACKGROUND

Melanoma is a deadly malignant skin cancer with common risk factors including prolonged ultraviolet exposure. Understanding the mechanisms of signal transducer and activator of transcription (STAT3) signaling and discovering inhibitors of STAT3 signaling are considered promising melanoma treatments for melanoma. Przewaquinone A (PrA), a lipophilic diterpene quinone isolated from Salvia przewalskii Maxim. var. mandarinorum (Diels) Stib, has been shown to have neuro-protective properties. Nevertheless, it remains unclear how PrA functions in the anti-melanoma process.

PURPOSE

Herein, the aim was to investigate the suppressive action of PrA on melanoma growth and metastasis as well as the underlying mechanisms.

METHODS

The in vitro proliferation ratio, cell migration, cell invasion, cell cycle and cell apoptosis were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) staining, wound-healing, transwell assays, flow cytometry and western blotting, respectively. The amount of STAT3 signaling-related proteins was determined using western blotting and immunofluorescence. The interaction between PrA and STAT3 was assessed using conducted by molecular docking, molecular dynamics (MD), surface plasmon resonance imaging (SPRi) and cellular thermal shift assay (CETSA). Autophagic fluxautophagic flux in melanoma cells was determined using the RFP-GFP-LC3 double-staining method. The STAT3C plasmid was used to overexpress STAT3 and investigate its role in the anti-melanoma action of PrA . The action of PrA on melanoma growth was validated in vivo.

RESULTS

PrA reduced cell proliferation, caused cell cycle arrest, and increased cell apoptosis, and inhibited cell migration and invasion. Additionally, PrA inhibited Src/STAT3 signaling and decreased the amount of STAT3 in the nucleus. We further confirmed that STAT3 was a direct target of PrA using molecular docking, MD, SPRi assay and CETSA. Additionally, STAT3 overexpression partially blocked the anti-melanoma effects of PrA. PrA induced autophagy in melanoma cells via STAT3 signaling. Moreover, combination with the autophagy inhibitors CQ (chloroquine) or 3MA (3-methyladenine) enhanced its anti-melanoma effects. PrA inhibited tumor growth and suppressed STAT3 signaling in vivo.

CONCLUSION

These findings collectively demonstrated that PrA inhibits the growth and metastasis of melanoma cells and induces protective autophagy of melanoma cells by inhibiting STAT3 signaling. Therefore, PrA may be a viable candidate for the treatment of melanoma and the results of this study may help to guide the development of new therapeutic approaches for patients with melanoma.

Eriodictyol-cisplatin coated nanomedicine synergistically promote osteosarcoma cells ferroptosis and chemosensitivity

The ever-increasing chemoresistance of osteosarcoma (OS) has been observed in the recent decades, impeding OS therapeutic improvement and posing an urgency to exploit to the alternative and/or supplementary therapies for the optimization of OS chemotherapeutic regimen. Ferroptosis, a regulated cell death, has been identified as a natural anticancer mechanism as well as a synergist for chemotherapeutics in various cancers. Herein, we affirmed the tumor-suppressing properties of eriodictyol and illustrated that its antitumor effects might ascribe to the ferroptosis-inducing activity, in which eriodictyol could bind with BACH1 to repress the transcription and translation of GPX4 and eventually result in the GPX4-related ferroptosis. Further investigation found that eriodictyol could exhibit a synergistic effect with cisplatin, facilitating the antitumor effects of cisplatin. Lastly, through utilizing hollow mesoporous prussian blue nanocubes loaded with eriodictyol and cisplatin, we formed the ferroptosis-synergistic nanocomplexes to facilitate OS cells ferroptosis and cisplatin sensitivity. Through direct catalytic oxidation of unsaturated lipids, exogenous iron delivery, GSH exhaustion, and GPX4 transcriptional inhibition, this ferroptosis-synergistic nanocomplex could excellently enhance OS cells ferroptosis in both vitro and vivo, with no obvious organ injury observed. Therefore, our ferroptosis-synergistic nanocomplex may represent a promising alternative therapeutic strategy for OS patients.

Realgar induces apoptosis by inhibiting glycolysis via regulating STAT3 in myelodysplastic syndrome

ETHNOPHARMACOLOGICAL RELEVANCE

Myelodysplastic syndrome (MDS) is a hematologic malignancy that presents a unique opportunity for traditional Chinese medicine (TCM) to demonstrate its distinctive value in treatment. Realgar, a component of TCM, has shown notable potential in alleviating clinical symptoms and improving the prognosis of MDS patients. However, the precise mechanisms underlying the treatment of MDS with realgar, particularly its effects on apoptosis-related pathways, remain poorly understood.

AIM OF THE STUDY

This study aimed to investigate the pro-apoptotic effects of realgar on MDS cells and to elucidate the underlying molecular mechanisms.

MATERIALS AND METHODS

We explored the targets and pathways of realgar's action on MDS using public databases, network pharmacology, and RNA sequencing. Various techniques were employed, including cell transfection, Cell Counting Kit-8 (CCK8) assay, Cellular Thermal Shift Assay (CETSA), Western blot (WB), quantitative real-time polymerase chain reaction (qRT-PCR), apoptosis and glycolysis assays, extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) measurements, dual-luciferase reporter assays, and immunofluorescence, to investigate the regulatory mechanisms involving STAT3, glycolysis, and apoptosis. Hematoxylin and eosin (HE) staining was utilized to assess realgar's toxicity. Apoptosis and hemogram changes were analyzed to evaluate the therapeutic effect of realgar on MDS transgenic mice.

RESULTS

Analysis of public data indicated that apoptosis-related genes are downregulated in MDS patients. Through network pharmacology, CETSA, qRT-PCR, WB, apoptosis assays, and STAT3 overexpression cell transfection, we discovered that realgar inhibits STAT3 expression. Further investigation using RNA sequencing suggested that glycolysis may be involved in this regulatory process. ECAR, OCR, glycolysis assays, WB, apoptosis assays, and glycolysis inhibitor experiments demonstrated that glycolytic function was inhibited. Additionally, GLUT1 expression was significantly decreased, and GLUT1 was found to directly bind to STAT3. In MDS mice, realgar treatment enhanced levels of white blood cells, red blood cells, hemoglobin, and platelets, and increased apoptosis levels.

CONCLUSION

Our findings reveal that realgar exerts a significant pro-apoptotic effect on MDS cells in both in vivo and in vitro models. Further analysis demonstrated that realgar regulates the STAT3 pathway, leading to GLUT1-mediated glycolysis alterations that ultimately induce apoptotic pathways, as represented by BCL2. These discoveries hold significant implications for the basic research and clinical diagnosis and treatment of MDS.

Verapamil attenuates myocardial ischemia/reperfusion injury by inhibiting apoptosis via activating the JAK2/STAT3 signaling pathway

Apoptosis is a crucial pathological process in myocardial ischemia/reperfusion injury (MIRI). Verapamil (Ver), normally used to treat hypertension or heart rhythm disorders, also attenuates MIRI. The potential of Ver to inhibit apoptosis and thereby attenuate MIRI remains unclear, as does the mechanism. We established an in vivo mouse ischemia/reperfusion (I/R) model by occlusion of the left anterior descending coronary. To construct a hypoxia/reoxygenation model in vitro, H9c2 cardiomyocytes were immersed in a hypoxic buffer in a hypoxia/anaerobic workstation. Ver significantly improved cardiac function and reduced myocardial infarction size in I/R mice, while decreasing apoptosis. Both in vivo and in vitro, application of Ver activated the JAK2/STAT3 signaling pathway and elevated Bcl-2 expression, while decreasing Bax and cleaved caspase-3 levels. Treatment with AG490, a JAK2 inhibitor, partially counteracted the anti-apoptotic and the cardioprotective effect of Ver. Thus, we conclude that Ver alleviates MIRI by reducing apoptosis via the JAK2/STAT3 signaling pathway activation. These findings provide a novel mechanism of Ver in the treatment of MIRI.

2'-Hydroxycinnamaldehyde Alleviates Intestinal Inflammation by Attenuating Intestinal Mucosal Barrier Damage Via Directly Inhibiting STAT3

BACKGROUND

The currently available clinical therapeutic drugs for ulcerative colitis (UC) are considered inadequate owing to certain limitations. There have been reports on the anti-inflammatory effects of 2'-hydroxycinnamaldehyde (HCA). However, whether HCA can improve UC is still unclear. Here, we aimed to investigate the pharmacological effects of HCA on UC and its underlying molecular mechanisms.

METHODS

The pharmacological effects of HCA were comprehensively investigated in 2 experimental setups: mice with dextran sulfate sodium (DSS)-induced colitis and lipopolysaccharide (LPS)-treated fetal human colon (FHC) cells. Furthermore, the interaction between HCA and signal transducer and activator of transcription 3 (STAT3) was investigated using molecular docking. The FHC cells with STAT3 knockdown or overexpression and mice with intestinal epithelium-specific STAT3 deletion (STAT3ΔIEC) were used to evaluate whether STAT3 mediated the pharmacological effects of HCA.

RESULTS

2'-Hydroxycinnamaldehyde attenuated dysregulated expression of inflammatory cytokines in a dose-dependent manner while increasing the expression of tight junction proteins, reducing the apoptosis of intestinal epithelial cells, and effectively alleviating inflammation both in vivo and in vitro. 2'-Hydroxycinnamaldehyde bound directly to STAT3 and inhibited its activation. The modulation of STAT3 activation levels due to STAT3 knockdown or overexpression influenced the mitigating effects of HCA on colitis. Further analysis indicated that the remission effect of HCA was not observed in STAT3ΔIEC mice, indicating that STAT3 mediated the anti-inflammatory effects of HCA.

CONCLUSIONS

We present a novel finding that HCA reduces colitis severity by attenuating intestinal mucosal barrier damage via STAT3. This discovery holds promise as a potential new strategy to alleviate UC.