Sophoraflavanone G induces apoptosis of human cancer cells by targeting upstream signals of STATs

Sophoraflavanone G: A review of the phytochemistry and pharmacology

Bioactive compounds derived from natural sources have long been investigated for the prevention and treatment of human diseases. Sophoraflavanone G (SFG), a lavandulyl flavanone naturally occurring in several Sophora plant species, belongs to the group of prenylated flavonoids that have garnered significant interest in contemporary research. The natural molecule exhibits a wide range of pharmacological properties and shows remarkable efficacy. Its ability to effectively suppress a range of malignant tumor cells, such as leukemia, breast cancer, and lung cancer, is attributed to its multi-target, multi-pathway, and multi-faceted mechanisms of action. Simultaneously, it can also alleviate various inflammatory diseases by mediating inflammatory mediators and molecular pathways. Furthermore, it has the capability to combat antibiotic resistance, exhibit synergistic antibacterial properties with diverse antibiotics, and prevent and treat various agricultural pests. Theoretically, it can bring benefits to human health and has potential value as a drug. Nevertheless, the drawbacks of poor water solubility and inadequate targeting cannot be overlooked. To comprehensively assess the current research on SFG, leverage its structural advantages and pharmacological activity, overcome its low bioavailability limitations, expedite its progression into a novel therapeutic drug, and better serve the clinic, this article presents a overall retrospect of the current research status of SFG. The discussion includes an analysis of the structural characteristics, physicochemical properties, bioavailability, pharmacological activities, and structure-activity relationships of SFG, with the goal of offering valuable insights and guidance for future research endeavors in this field.

Sophoraflavanone G Inhibits RANKL-Induced Osteoclastogenesis via MAPK/NF-κB Signaling Pathway

Osteoporosis is a common chronic bone metabolism disorder characterized by decreased bone mass and reduced bone density in the bone tissue. Osteoporosis can lead to increased fragility of the skeleton, making it prone to brittle fractures. Osteoclasts are macrophage-like cells derived from hematopoietic stem cells, and their excessive activity in bone resorption leads to lower bone formation than absorption during bone remodeling, which is one of the important factors inducing osteoporosis. Therefore, how to inhibit osteoclast formation and reducing bone loss is an important direction for treating osteoporosis. Sophoraflavanone G, derived from Sophora flavescens Alt and Rhizoma Drynariae, is a flavonoid compound with various biological activities. However, there have been few studies on osteoporosis and osteoclasts so far. Therefore, we hypothesize that genistein G can inhibit osteoclast differentiation, alleviate bone loss phenomenon, and conduct in vitro and in vivo experiments for research and verification purposes.

Sophoraflavanone G Resensitizes ABCG2-Overexpressing Multidrug-Resistant Non-Small-Cell Lung Cancer Cells to Chemotherapeutic Drugs

Elevated expression of the ATP-binding cassette (ABC) drug transporter ABCG2 in cancer cells contributes to the development of the multidrug resistance phenotype in patients with advanced non-small-cell lung cancer (NSCLC). Due to the lack of U.S. Food and Drug Administration (FDA)-approved synthetic inhibitors of ABCG2, significant efforts have been invested in discovering bioactive compounds of plant origin that are capable of reversing ABCG2-mediated multidrug resistance in cancer cells. Sophoraflavanone G (SFG), a phytoncide isolated from the plant species Sophora flavescens, is known to possess a wide spectrum of pharmacological activities, including antibacterial, anti-inflammatory, antimalarial, and antiproliferative effects. In the present study, the chemosensitizing effect of SFG in ABCG2-overexpressing NSCLC cells was investigated. Experimental results demonstrate that at subtoxic concentrations SFG significantly reversed ABCG2-mediated multidrug resistance in a concentration-dependent manner. Additional biochemical data and in silico docking analysis of SFG to the inward-open conformation of human ABCG2 indicate that SFG inhibited the drug transport function of ABCG2 by interacting with residues within the transmembrane substrate-binding pocket of ABCG2. Collectively, these findings provide evidence that SFG has the potential to be further tested as an effective inhibitor of ABCG2 to improve the efficacy of therapeutic drugs in patients with advanced NSCLC.

Biological effects and mechanisms of matrine and other constituents of Sophora flavescens in colorectal cancer

The plant Sophora flavescens Ait. has been used in the clinical management of colorectal cancer (CRC). Its constituent compounds, notably the alkaloids matrine, oxymatrine, and sophoridine, have received considerable research attention in experimental models of CRC in vivo and in vitro. This review found that extracts of S. flavescens and/or its constituent compounds have been reported to inhibit CRC cell proliferation by inducing cell-cycle arrest at the G1 phase, inducing apoptosis via the intrinsic pathway, interfering in cancer metabolism, inhibiting metastasis and angiogenesis, regulating senescence and telomeres, regulating the tumour microenvironment and down-regulating cancer-related inflammation. In addition, matrine and oxymatrine reversed multi-drug resistance and enhanced the effects of chemotherapies. These anti-cancer effects were associated with regulation of several cellular signalling pathways including: MAPK/ERK, PI3K/AKT/mTOR, p38MAPK, NF-κB, Hippo/LATS2, TGF-β/Smad, JAK/STAT3, RhoA/ROC, and Wnt/ β-catenin pathways. These multiple actions in CRC suggest the alkaloids of S. flavescens may be therapeutic candidates for CRC management. Nevertheless, there remains considerable scope for future research into its flavonoid constituents, the effects of combinations of compounds, and the interaction between these compounds and anti-cancer drugs. In addition, more research is needed to investigate likely drug ligand-receptor interactions for each of the bioactive compounds.

Involvement of mTOR-related signaling in antidepressant effects of Sophoraflavanone G on chronically stressed mice

SophoraflavanoneG (SG), an important prenylated flavonoid isolated from Sophoraalopecuroides.L, is effective for many illnesses. The present study was designed to investigate whether the compound could reverse depressive-like symptoms and investigate its possible mechanisms. Chronic Unpredictable Mild Stress (CUMS) mice were treated with fluoxetine and SG. The immobility time in forced swimming test (FST) and tail suspension test (TST) were recorded. The levels of pro-inflammatory cytokines and neurotransmitters in the hippocampus were evaluated. Furthermore, the protein expressions of PI3K, AKT, mTOR, p70S6K, BDNF, and Trkb in hippocampus were detected. Rapamycin, the selective mTOR inhibitor, was used to estimate the potential mechanism. As a result, after 7 days of SG treatment, the immobility time in FST and TST was declined obviously. The levels of IL-6, IL-1β, and TNF-α in the hippocampus were significantly reduced, and the quantity of 5-HT and NE was raised considerably in SG-treated group compared with the CUMS-exposed group. Additionally, SG could up-regulate the expressions of PI3K, AKT, mTOR, 70S6K, BDNF, and Trkb. The blockade of mammalian target of rapamycin signaling blunted the antidepressant effect and reversed the up-regulation of BDNF expression caused by SG. These findings suggested that SG treatment alleviated depressive-like symptoms via mTOR-mediated BDNF/Trkb signaling.

Highlighted STAT3 as a potential drug target for cancer therapy

Signal transducer and activator of transcription 3 (STAT3) is a cytoplasmic transcription factor that regulates cell proliferation, differentiation, apoptosis, angiogenesis, inflammation and immune responses. Aberrant STAT3 activation triggers tumor progression through oncogenic gene expression in numerous human cancers, leading to promote tumor malignancy. On the contrary, STAT3 activation in immune cells cause elevation of immunosuppressive factors. Accumulating evidence suggests that the tumor microenvironment closely interacts with the STAT3 signaling pathway. So, targeting STAT3 may improve tumor progression, and anti-cancer immune response. In this review, we summarized the role of STAT3 in cancer and the tumor microenvironment, and present inhibitors of STAT3 signaling cascades.

Sophoraflavanone G from Sophora flavescens induces apoptosis in triple-negative breast cancer cells

BACKGROUND

A compound isolated from Sophora flavescens-sophoraflavanone G (SG)-showed anti-tumor and anti-inflammatory properties. We previously demonstrated that SG promoted apoptosis in human leukemia HL-60 cells. In the present study, we investigated the effects of SG on apoptosis in human breast cancer MDA-MB-231 cells, and explored the underlying molecular mechanisms.

METHODS

MDA-MB-231 cells were treated with various SG concentrations, and cell viability was evaluated by MTT assay. Apoptotic signal proteins were detected by western blotting, and cell apoptosis was assessed using flow cytometry.

RESULTS

Our results demonstrated that SG induced nuclear condensation, DNA fragmentation, reactive oxygen species production, and increased cell apoptosis in MDA-MB-231 cells. SG also suppressed migration and invasion, likely via blockage of the MAPK pathway. In the apoptotic signaling pathway, SG increased cleaved caspase-8, caspase-3, and caspase-9. SG treatment also decreased Bcl-2 and Bcl-xL expression, increased Bax expression, and prompted release of more cytochrome c from mitochondria to the cytoplasm in MDA-MB-231 cells.

CONCLUSION

Overall, our findings suggest that SG might increase apoptosis, and decrease migration and invasion, in MDA-MB-231 cells through suppression of a MAPK-related pathway.

Biologically active prenylated flavonoids from the genus Sophora and their structure-activity relationship-A review

The genus Sophora (Fabaceae) has been used in traditional medicine for years. Prenylated flavonoids are one of the constituents of Sophora species that play important roles in their biological properties. Different classes of prenylated flavonoids are produced by Sophora spp. including prenylated flavonol (e.g., sophoflavescenol), prenylated flavanone (e.g., sophoraflavanone G), prenylated flavonostilbene (e.g., alopecurones A and B), and prenylated chalcone (kuraridin). Prenylated flavonoids have a more lipophilic structure, which leads to its high affinity to the cell membranes and enhancement of the biological activity, which includes cytotoxicity, antibacterial, anti-inflammatory, and estrogenic activities. However, it is reported that prenylation decreases the plasma absorption but increases the tissue accumulation. The presence of the prenyl or lavandulyl groups on C8 position of flavonoids plays an important role in the biological activity. It seems that prenylated flavonoids have the potential to be developed as new drugs or supplements for human health.

Ginkgolic Acid C 17:1, Derived from Ginkgo biloba Leaves, Suppresses Constitutive and Inducible STAT3 Activation through Induction of PTEN and SHP-1 Tyrosine Phosphatase

Ginkgolic acid C 17:1 (GAC 17:1) extracted from Ginkgo biloba leaves, has been previously reported to exhibit diverse antitumor effect(s) through modulation of several molecular targets in tumor cells, however the detailed mechanism(s) of its actions still remains to be elucidated. Signal transducer and activator of transcription 3 (STAT3) is an oncogenic transcription factor that regulates various critical functions involved in progression of diverse hematological malignancies, including multiple myeloma, therefore attenuating STAT3 activation may have a potential in cancer therapy. We determined the anti-tumor mechanism of GAC 17:1 with respect to its effect on STAT3 signaling pathway in multiple myeloma cell lines. We found that GAC 17:1 can inhibit constitutive activation of STAT3 through the abrogation of upstream JAK2, Src but not of JAK1 kinases in U266 cells and also found that GAC can suppress IL-6-induced STAT3 phosphorylation in MM.1S cells. Treatment of protein tyrosine phosphatase (PTP) inhibitor blocked suppression of STAT3 phosphorylation by GAC 17:1, thereby indicating a critical role for a PTP. We also demonstrate that GAC 17:1 can induce the substantial expression of PTEN and SHP-1 at both protein and mRNA level. Further, deletion of PTEN and SHP-1 genes by siRNA can repress the induction of PTEN and SHP-1, as well as abolished the inhibitory effect of drug on STAT3 phosphorylation. GAC 17:1 down-regulated the expression of STAT3 regulated gene products and induced apoptosis of tumor cells. Overall, GAC 17:1 was found to abrogate STAT3 signaling pathway and thus exert its anticancer effects against multiple myeloma cells.

Inhibition of interleukin-3- and interferon- α-induced JAK/STAT signaling by the synthetic α-X-2′,3,4,4′-tetramethoxychalcones α-Br-TMC and α-CF3-TMC

The JAK/STAT pathway is an essential mediator of cytokine signaling, often upregulated in human diseases and therefore recognized as a relevant therapeutic target. We previously identified the synthetic chalcone α-bromo-2′,3,4,4′-tetramethoxychalcone (α-Br-TMC) as a novel JAK2/STAT5 inhibitor. We also found that treatment with α-Br-TMC resulted in a downward shift of STAT5 proteins in SDS-PAGE, suggesting a post-translational modification that might affect STAT5 function. In the present study, we show that a single cysteine within STAT5 is responsible for the α-Br-TMC-induced protein shift, and that this modification does not alter STAT5 transcriptional activity. We also compared the inhibitory activity of α-Br-TMC to that of another synthetic chalcone, α-trifluoromethyl-2′,3,4,4′-tetramethoxychalcone (α-CF3-TMC). We found that, like α-Br-TMC, α-CF3-TMC inhibits JAK2 and STAT5 phosphorylation in response to interleukin-3, however without altering STAT5 mobility in SDS-PAGE. Moreover, we demonstrate that both α-Br-TMC and α-CF3-TMC inhibit interferon-α-induced activation of STAT1 and STAT2, by inhibiting their phosphorylation and the expression of downstream interferon-stimulated genes. Together with the previous finding that α-Br-TMC and α-CF3-TMC inhibit the response to inflammation by inducing Nrf2 and blocking NF-κB activities, our data suggest that synthetic chalcones might be useful as anti-inflammatory, anti-cancer and immunomodulatory agents in the treatment of human diseases.

Antiproliferative and proapoptotic effects of a pyrrole containing arylthioindole in human Jurkat leukemia cell line and multidrug-resistant Jurkat/A4 cells

Recently, a series of novel arylthioindole compounds, potent inhibitors of tubulin polymerization and cancer cell growth, were synthesized. In the present study the effects of 2-(1H-pyrrol-3-yl)-3-((3,4,5-trimethoxyphenyl)thio)-1H-indole (ATI5 compound) on cell proliferation, cell cycle progression, and induction of apoptosis in human T-cell acute leukemia Jurkat cells and their multidrug resistant Jurkat/A4 subline were investigated. Treatment of the Jurkat cells with the ATI5 compound for 48 hrs resulted in a strong G2/M cell cycle arrest and p53-independent apoptotic cell death accompanied by the induction of the active form of caspase-3 and poly(ADP-ribose) polymerase-1 (PARP-1) cleavage. ATI5 treatment also caused non-cell death related mitotic arrest in multidrug resistant Jurkat/A4 cells after 48 hrs of treatment suggesting promising opportunities for the further design of pyrrole-containing ATI compounds as anticancer agents. Cell death resistance of Jurkat/A4 cells to ATI5 compound was associated with alterations in the expression of pro-survival and anti-apoptotic protein-coding and microRNA genes. More importantly, findings showing that ATI5 treatment induced p53-independent apoptosis are of great importance from a therapeutic point of view since p53 mutations are common genetic alterations in human neoplasms.

The Chemopreventive Phytochemical Moringin Isolated from Moringa oleifera Seeds Inhibits JAK/STAT Signaling

Sulforaphane (SFN) and moringin (GMG-ITC) are edible isothiocyanates present as glucosinolate precursors in cruciferous vegetables and in the plant Moringa oleifera respectively, and recognized for their chemopreventive and medicinal properties. In contrast to the well-studied SFN, little is known about the molecular pathways targeted by GMG-ITC. We investigated the ability of GMG-ITC to inhibit essential signaling pathways that are frequently upregulated in cancer and immune disorders, such as JAK/STAT and NF-κB. We report for the first time that, similarly to SFN, GMG-ITC in the nanomolar range suppresses IL-3-induced expression of STAT5 target genes. GMG-ITC, like SFN, does not inhibit STAT5 phosphorylation, suggesting a downstream inhibitory event. Interestingly, treatment with GMG-ITC or SFN had a limited inhibitory effect on IFNα-induced STAT1 and STAT2 activity, indicating that both isothiocyanates differentially target JAK/STAT signaling pathways. Furthermore, we showed that GMG-ITC in the micromolar range is a more potent inhibitor of TNF-induced NF-κB activity than SFN. Finally, using a cellular system mimicking constitutive active STAT5-induced cell transformation, we demonstrated that SFN can reverse the survival and growth advantage mediated by oncogenic STAT5 and triggers cell death, therefore providing experimental evidence of a cancer chemopreventive activity of SFN. This work thus identified STAT5, and to a lesser extent STAT1/STAT2, as novel targets of moringin. It also contributes to a better understanding of the biological activities of the dietary isothiocyanates GMG-ITC and SFN and further supports their apparent beneficial role in the prevention of chronic illnesses such as cancer, inflammatory diseases and immune disorders.

Sophoraflavanone G prevents Streptococcus mutans surface antigen I/II-induced production of NO and PGE2 by inhibiting MAPK-mediated pathways in RAW 264.7 macrophages

BACKGROUND

Sophora flavescens AITON (Leguminosae) is a typical traditional Korean medical herb considered to exhibit antibacterial, anti-inflammatory, and antipyretic effects, and is also used for the treatment of skin and mucosal ulcers, sores, diarrhea, gastrointestinal hemorrhage, arrhythmia, and eczema.

OBJECTIVE AND DESIGN

This study examined the inhibitory effects of sophoraflavanone G (SF) of S. flavescens on the bacterial fibrillar protein, Antigen I/II (AgI/II)-N recombinant protein isolated from Streptococcus mutans(rAg I/II)-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2). The investigation was focused on whether SF could inhibit the production of proinflammatory mediators such as nitric oxide (NO) and prostaglandin (PG) E2 as well as the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-a, interleukin (IL)-6, nuclear factor (NF)-κB and mitogen-activated protein kinases (MAPKs) in rAgI/II-stimulated RAW 264.7 cells using Griess reagent, Enzyme linked immunosorbent assay (ELISA), and Western blotting analysis.

RESULTS

SG significantly inhibited the production of NO and PGE2 and pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor α in Ag I/II-N-stimulated RAW264.7 cells, which were mediated by the down-regulation of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. The SF inhibited the phosphorylation of IκB-α, nuclear translocation of p65, and subsequent activation of NF- κB in the rAgI/II-stimulated cells. In addition, the SF suppressed the rAgI/II-stimulated activation of ERK MAPK as well as the MAPK inhibitor significantly reduced the rAgI/II-induced production of NO and PGE2.

CONCLUSION

Collectively, we suggest that the SF inhibits the expression and production of inflammatory mediators by blocking the ERK MAPK mediated pathway and inhibiting the activation of NF-κB.

Sophoraflavanone G Induces Apoptosis in Human Leukemia Cells and Blocks MAPK Activation

Sophoraflavanone G (SG) was isolated from Sophora flavescens. Previously, we have found that SG is able to suppress the inflammatory response in lipopolysaccharide-stimulated RAW 264.7 macrophages. This study aimed to evaluate the effects of SG on apoptosis, and explore its molecular mechanism in human leukemia HL-60 cells. HL-60 cells were treated with various concentrations of SG (3–30 [Formula: see text]M). The viability of the HL-60 cells was assessed using the MTT method, and the nuclear condensation indicative of apoptosis was observed by DAPI fluorescence staining. In addition, apoptotic signal proteins were examined using Western blotting. The results showed that apoptosis, including DNA fragmentation and nuclear condensation, increased significantly in SG-treated HL-60 cells. SG activated caspase-3 and caspase-9, and downregulated Bcl-2 and Bcl-xL. SG also upregulated Bax and released cytochrome c from the mitochondria into the cytoplasm, enabling apoptosis via the mitochondrially-mediated “intrinsic” pathway. Additionally, SG was able to cleave poly (ADP-ribose) polymerase 1 and activate mitogen-activated protein kinase (MAPK) pathways. These results suggest that SG might increase the effect of apoptosis on HL-60 cells through caspase-3 activation, mitochondrial-mediated pathways, and the MAPK pathway.

Ginkgetin Blocks Constitutive STAT3 Activation and Induces Apoptosis through Induction of SHP-1 and PTEN Tyrosine Phosphatases

Ginkgetin, a biflavone from Ginkgo biloba leaves, is known to exhibit antiinflammatory, antifungal, neuroprotective, and antitumor activities, but its precise mechanism of action has not been fully elucidated. Because the aberrant activation of STAT3 has been linked with regulation of inflammation, proliferation, invasion, and metastasis of tumors, we hypothesized that ginkgetin modulates the activation of STAT3 in tumor cells. We found that ginkgetin clearly suppressed constitutive phosphorylation of STAT3 through inhibition of the activation of upstream JAK1 and c-Src kinases and nuclear translocation of STAT3 on both A549 and FaDu cells. Treatment with sodium pervanadate reversed the ginkgetin-induced down-modulation of STAT3, thereby indicating a critical role for a PTP. We also found that ginkgetin strongly induced the expression of the SHP-1 and PTEN proteins and its mRNAs. Further, deletion of SHP-1 and PTEN genes by siRNA suppressed the induction of SHP-1 and PTEN, and reversed the inhibition of STAT3 activation. Ginkgetin induced apoptosis as characterized by an increased accumulation of cells in subG1 phase, positive Annexin V binding, loss of mitochondrial membrane potential, down-regulation of STAT3-regulated gene products, and cleavage of PARP. Overall, ginkgetin abrogates STAT3 signaling pathway through induction of SHP-1 and PTEN proteins, thus attenuating STAT3 phosphorylation and tumorigenesis.

Photoprotective Potential of Penta-O-Galloyl-β-DGlucose by Targeting NF-κB and MAPK Signaling in UVB Radiation-Induced Human Dermal Fibroblasts and Mouse Skin

Exposure of the skin to ultraviolet radiation can cause skin damage with various pathological changes including inflammation. In the present study, we identified the skin-protective activity of 1,2,3,4,6-penta-O-galloyl-β-D-glucose (pentagalloyl glucose, PGG) in ultraviolet B (UVB) radiation-induced human dermal fibroblasts and mouse skin. PGG exhibited antioxidant activity with regard to intracellular reactive oxygen species (ROS) generation as well as ROS and reactive nitrogen species (RNS) scavenging. Furthermore, PGG exhibited anti-inflammatory activity, inhibiting the activation of nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling, resulting in inhibition of the expression of pro-inflammatory mediators. Topical application of PGG followed by chronic exposure to UVB radiation in the dorsal skin of hairless mice resulted in a significant decrease in the progression of inflammatory skin damages, leading to inhibited activation of NF-κB signaling and expression of pro-inflammatory mediators. The present study demonstrated that PGG protected from skin damage induced by UVB radiation, and thus, may be a potential candidate for the prevention of environmental stimuli-induced inflammatory skin damage.

Enriched inhibition of cancer and stem-like cancer cells via STAT-3 modulating niclocelles

We describe for the first time a therapeutic strategy to target stem-like cancer cells via STAT-3 modulation using a nanomedicine approach. Niclocelle, a niclosamide loaded rigid core mixed micelle, was synthesized from a self-assembled well-defined amphiphilic diblock copolymer and an FDA-approved signal transducer and activator of transcription factor 3. Followed by a rigorous physico-chemical characterization, niclocelles were evaluated biologically for cytotoxicity and apoptosis in human melanoma (C32) and breast cancer (MDA-MB231 and MCF-7) cells. Niclocelles were found to selectively reduce the CD44+ stem cell population in C32 cells via STAT-3 modulation.

Alantolactone selectively suppresses STAT3 activation and exhibits potent anticancer activity in MDA-MB-231 cells

The important goal of cancer drug discovery is to develop therapeutic agents that are effective, safe, and affordable. In the present study, we demonstrated that alantolactone, which is a sesquiterpene lactone, has potential activity against triple-negative breast cancer MDA-MB-231 cells by suppressing the signal transducer and activator of transcription 3 (STAT3) signaling pathway. Alantolactone effectively suppressed both constitutive and inducible STAT3 activation at tyrosine 705. Alantolactone decreased STAT3 translocation to the nucleus, its DNA-binding, and STAT3 target gene expression. Alantolactone significantly inhibits STAT3 activation with a marginal effect on MAPKs and on NF-κB transcription; however, this effect is not mediated by inhibiting STAT3 upstream kinases. Although SHP-1, SHP-2, and PTEN, which are protein tyrosine phosphatases (PTPs), were not affected by alantolactone, the treatment with a PTP inhibitor reversed the alantolactone-induced suppression of STAT3 activation, indicating that PTP plays an important role in the action of alantolactone. Finally, alantolactone treatment resulted in the inhibition of migration, invasion, adhesion, and colony formation. The in vivo administration of alantolactone inhibited the growth of human breast xenograft tumors. These results provide preclinical evidence to continue the development of alantolactone as a STAT3 inhibitor and as a potential therapeutic agent against breast cancer.

Metformin enhances the anti-adipogenic effects of atorvastatin via modulation of STAT3 and TGF-β/Smad3 signaling

Adipocyte accumulation is associated with the development of obesity and obesity-related diseases. Interactions of master transcription factors and signaling cascades are required for adipogenesis. Regulation of excessive adipogenic processes may be an attractive therapeutic for treatment of obesity and obesity-related diseases. In this study, we found that atorvastatin exerts an anti-adipogenic activity in 3T3-L1 pre-adipocytes, and that this activity is elevated in combination with metformin. Expression of the adipogenic master regulators PPARγ and C/EBPα, and their target gene aP2, was suppressed by atorvastatin. Furthermore, atorvastatin treatment resulted in increased activation of the key master regulator of cellular energy homeostasis, AMPK. These biological activities of atorvastatin were elevated in combination with metformin. These anti-adipogenic activities were associated with regulation of the STAT3 and TGF-β signaling cascades, resulting in the regulation of the expression of STAT3 target genes, such as KLF5, p53, and cyclin D1, and TGF-β signaling inhibitory genes, such as SMAD7. Our results suggest that combination therapy with atorvastatin and metformin may have therapeutic potential for the treatment of obesity and obesity-related diseases caused by excessive adipogenesis.

Fufang Kushen injection inhibits sarcoma growth and tumor-induced hyperalgesia via TRPV1 signaling pathways

Cancer pain is a deleterious consequence of tumor growth and related inflammation. Opioids and anti-inflammatory drugs provide first line treatment for cancer pain, but both are limited by side effects. Fufang Kushen injection (FKI) is GMP produced, traditional Chinese medicine used alone or with chemotherapy to reduce cancer-associated pain. FKI limited mouse sarcoma growth both in vivo and in vitro, in part, by reducing the phosphorylation of ERK and AKT kinases and BAD. FKI inhibited TRPV1 mediated capsaicin-induced ERK phosphorylation and reduced tumor-induced proinflammatory cytokine production. Thus, FKI limited cancer pain both directly by blocking TRPV1 signaling and indirectly by reducing tumor growth.

The natural chemopreventive agent sulforaphane inhibits STAT5 activity

Signal transducer and activator of transcription STAT5 is an essential mediator of cytokine, growth factor and hormone signaling. While its activity is tightly regulated in normal cells, its constitutive activation directly contributes to oncogenesis and is associated to a number of hematological and solid tumor cancers. We previously showed that deacetylase inhibitors can inhibit STAT5 transcriptional activity. We now investigated whether the dietary chemopreventive agent sulforaphane, known for its activity as deacetylase inhibitor, might also inhibit STAT5 activity and thus could act as a chemopreventive agent in STAT5-associated cancers. We describe here sulforaphane (SFN) as a novel STAT5 inhibitor. We showed that SFN, like the deacetylase inhibitor trichostatin A (TSA), can inhibit expression of STAT5 target genes in the B cell line Ba/F3, as well as in its transformed counterpart Ba/F3-1*6 and in the human leukemic cell line K562 both of which express a constitutively active form of STAT5. Similarly to TSA, SFN does not alter STAT5 initial activation by phosphorylation or binding to the promoter of specific target genes, in favor of a downstream transcriptional inhibitory effect. Chromatin immunoprecipitation assays revealed that, in contrast to TSA however, SFN only partially impaired the recruitment of RNA polymerase II at STAT5 target genes and did not alter histone H3 and H4 acetylation, suggesting an inhibitory mechanism distinct from that of TSA. Altogether, our data revealed that the natural compound sulforaphane can inhibit STAT5 downstream activity, and as such represents an attractive cancer chemoprotective agent targeting the STAT5 signaling pathway.

Transcription Factor STAT3 as a Novel Molecular Target for Cancer Prevention

Signal Transducers and Activators of Transcription (STATs) are a family of transcription factors that regulate cell proliferation, differentiation, apoptosis, immune and inflammatory responses, and angiogenesis. Cumulative evidence has established that STAT3 has a critical role in the development of multiple cancer types. Because it is constitutively activated during disease progression and metastasis in a variety of cancers, STAT3 has promise as a drug target for cancer therapeutics. Recently, STAT3 was found to have an important role in maintaining cancer stem cells in vitro and in mouse tumor models, suggesting STAT3 is integrally involved in tumor initiation, progression and maintenance. STAT3 has been traditionally considered as nontargetable or undruggable, and the lag in developing effective STAT3 inhibitors contributes to the current lack of FDA-approved STAT3 inhibitors. Recent advances in cancer biology and drug discovery efforts have shed light on targeting STAT3 globally and/or specifically for cancer therapy. In this review, we summarize current literature and discuss the potential importance of STAT3 as a novel target for cancer prevention and of STAT3 inhibitors as effective chemopreventive agents.

The synthetic α-bromo-2',3,4,4'-tetramethoxychalcone (α-Br-TMC) inhibits the JAK/STAT signaling pathway

Signal transducer and activator of transcription STAT5 and its upstream activating kinase JAK2 are essential mediators of cytokine signaling. Their activity is normally tightly regulated and transient. However, constitutive activation of STAT5 is found in numerous cancers and a driving force for malignant transformation. We describe here the identification of the synthetic chalcone α-Br-2′,3,4,4′-tetramethoxychalcone (α-Br-TMC) as a novel JAK/STAT inhibitor. Using the non-transformed IL-3-dependent B cell line Ba/F3 and its oncogenic derivative Ba/F3-1*6 expressing constitutively activated STAT5, we show that α-Br-TMC targets the JAK/STAT pathway at multiple levels, inhibiting both JAK2 and STAT5 phosphorylation. Moreover, α-Br-TMC alters the mobility of STAT5A/B proteins in SDS-PAGE, indicating a change in their post-translational modification state. These alterations correlate with a decreased association of STAT5 and RNA polymerase II with STAT5 target genes in chromatin immunoprecipitation assays. Interestingly, expression of STAT5 target genes such as Cis and c-Myc was differentially regulated by α-Br-TMC in normal and cancer cells. While both genes were inhibited in IL-3-stimulated Ba/F3 cells, expression of the oncogene c-Myc was down-regulated and that of the tumor suppressor gene Cis was up-regulated in transformed Ba/F3-1*6 cells. The synthetic chalcone α-Br-TMC might therefore represent a promising novel anticancer agent for therapeutic intervention in STAT5-associated malignancies.