Curcumol Attenuates Endometriosis by Inhibiting the JAK2/STAT3 Signaling Pathway.

BACKGROUND Curcumol is a hydrogenated austenitic compound with hemiketal. In this study we evaluated the effects of curcumol on local inflammatory response, cell proliferation, and metastasis in endometriosis, and elucidated the underlying mechanisms. MATERIAL AND METHODS Ectopic endometrial stromal cells were treated with increasing doses of curcumol. The MTT assay was used to assess cell viability. FITC-labeled annexin-V/PI double-staining method and flow cytometry were used to determine cell apoptosis. Cell migration was evaluated using a wound healing assay. ELISA kits were used to detect the levels of TNF-alpha, IL-6, and IL-1ß. Western blot assay was used to examine the phosphorylation degree of JAK2 and STAT3 and the expression of Bax, Bcl2, and caspase-3 proteins. Autologous endometrial transplantation was used to establish a rat model to assess the anti-EMS effect of curcumol in vivo. RESULTS Curcumol can inhibit the proliferation of ectopic endometrial stromal cells, promote cell apoptosis, and weaken cell migration ability. Curcumol can reduce the expression of Bax and caspase-3 protein and increase the expression of Bcl2 protein. Curcumol also can inhibit the secretion of inflammatory cytokines, including tumor necrosis cytokines (TNF)-alpha, interleukin (IL)-6, and IL-1ß, by ectopic endometrial stromal cells. In addition, curcumol can also inhibit the phosphorylation of JAK2 and STAT3. In vivo experiments also proved that curcumol could inhibit the growth of ectopic lesions in EMS model rats. CONCLUSIONS Curcumol can inhibit the JAK2/STAT3 pathway, reduce the inflammatory cytokines secreted by ectopic endometrial stromal cells, inhibit cell proliferation and migration, and reduce the volume of ectopic lesions.

Arginine reverses growth hormone resistance through the inhibition of toll-like receptor 4-mediated inflammatory pathway.

OBJECTIVE: Growth hormone stimulates growth by increasing insulin-like growth factor 1 expression and secretion. In the presence of insufficient nutrients, GH increases, whereas IGF-1 expression becomes severely suppressed, leading to GH resistance. This study aimed to explore the effect of arginine (Arg) on GH resistance during malnutrition and to describe its underlying mechanism. METHODS: C57BL/6J mice were injected intraperitoneally with Arg for 1h or subjected to caloric restriction with Arg supplement in drinking water for 18days. HepG2 cells were exposed to different Arg concentrations for 24h. Signaling pathway agonists/inhibitors, siRNA, and overexpression plasmids were used to investigate the underlying molecular mechanism. Liver-specific toll-like receptor (TLR4) knockout mice were utilized to clarify the role of TLR4 in Arg-induced IGF-I expression and secretion. RESULTS: Arg inhibited the TLR4 downstream pathway by binding to TLR4 and consequently activated Janus kinase 2/signal transducer and activator of transcription 5 signaling pathway. As a result, IGF-1 transcription and secretion increased. Arg activity was absent in liver-specific TLR4 knockout mice and was greatly suppressed in liver with overexpressed TLR4, suggesting that hepatic TLR4 was required and sufficient to induce GH resistance. By contrast, the mammalian target of rapamycin pathway was unnecessary for Arg activity. Arg not only significantly increased IGF-1 expression and secretion under acute fasting and chronic CR conditions but also attenuated body weight loss. CONCLUSIONS: Our results demonstrate a previously unappreciated pathway involving Arg that reverses GH resistance and alleviates malnutrition-induced growth restriction through the inhibition of TLR4-mediated inflammatory pathway.

Antitumor effects of herbal mixture extract in the pancreatic adenocarcinoma cell line PANC1.

A recent study showned that complementary medicine is gradually gaining wide acceptance. In the present study, the herbal mixture extract (H3) composed of 3 oriental herbal plants was investigated for anticancer activity in vitro and in vivo. H3 inhibited PANC1 cell growth by promoting G0/G1 arrest (11% increase) and apoptotic cell death (9% increase). H3 also suppressed stem cell-like side population cells (4% decrease) and migration activity (24% decrease). In contrast, gemcitabine decreased side population cells and migration activity by 3 and 11%, respectively. These effects of H3 and gemcitabine were further studied by examining the expression of apoptosis-associated genes (CXCR4, JAK2 and XIAP) and stem cell-associated genes (ABCG2, POU5F1 and SOX2). We also found that H3 suppressed tumor growth by 46% in a PANC1­xenograft model, while gemcitabine caused a 36% decrease. The antitumor effects of H3 were confirmed by western blot analysis for COX-2 and cytochrome c expression. Furthermore, necrotic cell death and erythrocyte-containing cavities were detected in tumor tissue by hematoxylin and eosin (H&E) staining. Notably, the combinatorial therapy (H3 and gemcitabine) increased tumor growth compared to that in the control. In conclusion, the present study shows that H3 has promise as a therapeutic agent against pancreatic cancer and its cancer stem cells.

Inhibition of the JAK2/STAT3 signaling pathway exerts a therapeutic effect on osteosarcoma.

Osteosarcoma (OS) is the most common type of malignant bone tumor. Despite aggressive multimodal treatments, including surgical resection, chemotherapy and adjunctive immunotherapies, patients with OS with high-grade malignancy have a poor five-year survival rate that has remained unchanged over the past two decades, highlighting the urgent requirement for novel therapeutic approaches. Signal transducers and activators of transcription 3 (STAT3) has been implicated as an oncogene and therapeutic target in a variety of neoplastic diseases. The aim of the present study was to determine whether inhibition of the janus kinase 2 (JAK2)/STAT3 pathway by FLLL32, a specific JAK2/STAT3 inhibitor, is able to provide a potential therapy for OS. FLLL32 inhibited OS cell growth in vitro and delayed OS growth in an OS xenograft nude mouse model. STAT3 knockdown by short hairpin RNA delayed OS formation in vivo. Thus, the JAK2/STAT3 pathway is important in OS formation. Efficacy of the FLLL32 pharmacological inhibitor in delaying OS growth suggests that targeting JAK2/STAT3 may be a potential therapeutic strategy for patients with OS.

2-Methoxystypandrone inhibits signal transducer and activator of transcription 3 and nuclear factor-κB signaling by inhibiting Janus kinase 2 and IκB kinase.

Constitutive activation of the signal transducer and activator of transcription 3 (STAT3) or the nuclear factor-κB (NF-κB) pathway occurs frequently in cancer cells and contributes to oncogenesis. The activation of Janus kinase 2 (JAK2) and IκB kinase (IKK) are key events in STAT3 and NF-κB signaling, respectively. We have identified 2-methoxystypandrone (2-MS) from a traditional Chinese medicinal herb Polygonum cuspidatum as a novel dual inhibitor of JAK2 and IKK. 2-MS inhibits both interleukin-6-induced and constitutively-activated STAT3, as well as tumor necrosis factor-α-induced NF-κB activation. 2-MS specifically inhibits JAK and IKKß kinase activities but has little effect on activities of other kinases tested. The inhibitory effects of 2-MS on STAT3 and NF-κB signaling can be eliminated by DTT or glutathione and can last for 4 h after a pulse treatment. Furthermore, 2-MS inhibits growth and induces death of tumor cells, particularly those with constitutively-activated STAT3 or NF-κB signaling. We propose that the natural compound 2-MS, as a potent dual inhibitor of STAT3 and NF-κB pathways, is a promising anticancer drug candidate.

Negative regulation of JAK2 by H3K9 methyltransferase G9a in leukemia.

Histone methylation at specific lysine residues is a crucial regulatory process in transcriptional regulation. Using chromatin immunoprecipitation with microarray technology (ChIP-chip) analysis, we found that the H3K9-me2 target gene JAK2 was an important factor during differentiation of the HL-60 promyelocytic leukemia cell line by all-trans-retinoic acid (ATRA) treatment. Here, we report that the H3K9 methyltransferase G9a negatively regulated JAK2 transcription in histone methyltransferase activity and in a YY1-dependent manner during ATRA-mediated leukemia cell differentiation. We found that G9a knockdown repressed ATRA-mediated HL-60 cell differentiation. We demonstrated that G9a interacts with YY1 and is recruited to the JAK2 promoter along with corepressors, including histone deacetylase, that induced H3K9-me2. Repression of JAK2 transcription by G9a decreased H3Y41 phosphorylation and promoted inhibition of the recently identified JAK2-H3Y41P-HP1α pathway-mediated leukemogenesis.

Hypothalamic SOCS-3 expression and the effect of intracerebroventricular angiotensin II injection on water intake and renal sodium handling in SHR.

In rats, the acute central dipsogenic and natriuretic action of angiotensin II (AngII) seems to be independent of the hemodynamic effects of the peptide; however, in genetically hypertensive models, this relationship has not yet been investigated. It has been demonstrated that AngII induces the suppressor of cytokine signaling (SOCS-3) expression in the brain that, in turn, modulates further activation of the pathway, leading to desensitization to AngII stimuli with regard to its dipsogenic effect. This study investigates age-related Janus kinase (JAK-2) and SOCS-3 hypothalamic expression, by immunoblotting, and the involvement of SOCS-3 expression in urinary sodium handling and dipsogenic response in spontaneously hypertensive rats (SHR), compared with age-matched Wistar-Kyoto (WKy) rats. The intracerebroventricular (i.c.v.) application of AngII significantly enhanced the dipsogenic response, reduced C(Cr), and reciprocally promoted increased absolute and fractional rates of excretion of sodium in WKy rats. The central AngII-induced dipsogenic effect in WKy and SHR was significantly attenuated by prior i.c.v. administration of DUP753. In addition, the magnitude of the dipsogenic and renal response to AngII was significantly attenuated in age-matched SHR. Blocking of hypothalamic SOCS-3 expression by an antisense oligonucleotide resulted in partial reversal of the refractory nature of AngII in thirst responses in SHR. The altered centrally applied AngII response in SHR associated with increased hypothalamic JAK-2/SOCS-3 expression may suggest that abnormal regulation of the central angiotensin pathways may contribute to dysfunction of water-electrolyte homeostasis in SHR.