• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7439-7444
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• 2013

Aim: ATF3, a member of the ATF/CREB family of transcription factors, has been found to be selectively induced by calcineurin/NFAT inhibition and to enhance keratinocyte tumor formation, although the precise role of ATF3 in human skin cancer and possible mechanisms remain unknown. Methods: In this study, clinical analysis of 30 skin cancer patients and 30 normal donors revealed that ATF3 was accumulated in skin cancer tissues. Functional assays demonstrated that ATF3 significantly promoted skin cancer cell proliferation. Results: Mechanically, ATF3 activated Stat3 phosphorylation in skin cancer cell through regulation of p53 expression. Moreover, the promotion effect of ATF3 on skin cancer cell proliferation was dependent on the p53-Stat3 signaling cascade. Conclusion: Together, the results indicate that ATF3 might promote skin cancer cell proliferation and enhance skin keratinocyte tumor development through inhibiting p53 expression and then activating Stat3 phosphorylation.

• Biomolecules & Therapeutics
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• v.25 no.5
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• pp.535-544
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• 2017

Carnosol is a phenolic antioxidant present in rosemary (Rosmarinus officinalis). It is known for anti-inflammatory effects, analgesic activity and anti-cancer effects. However, no study has been dedicated yet to its effect on atopic dermatitis (AD). Here, we show that carnosol effectively inhibited LPS-induced nitric oxide (NO) generation and expression of inflammatory marker proteins (iNOS and COX-2) in RAW 264.7 cells. In addition, carnosol effectively inhibits the phosphorylation of STAT3 and DNA binding activity in RAW 264.7 cells. Pull down assay and docking model analysis showed that carnosol directly binds to the DNA binding domain (DBD) of STAT3. We next examined the anti-atopic activity of carnosol ($0.05{\mu}g/cm^2$) using 5% Phthalic anhydride (PA)-induced AD model in HR1 mice. Carnosol treatment significantly reduced 5% PA-induced AD like skin inflammation in skin tissues compared with control mice. Moreover, carnosol treatment inhibits the expression of iNOS and COX-2 in skin tissue. In addition, the levels of $TNF-{\alpha}$, $IL-1{\beta}$, and Immunoglobulin-E in blood serum was significantly decreased in carnosol treated mice compared with those of 5% PA treated group. Furthermore, the activation of STAT3 in skin tissue was decreased in carnosol treated mice compared with control mice. In conclusion, these findings suggest that carnosol exhibited a potential anti-AD activity by inhibiting pro-inflammatory mediators through suppression of STAT3 activation via direct binding to DBD of STAT3.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.15
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• pp.6161-6164
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• 2014

Background: We have reported the radiation could activate STAT3, which subsequently promotes the invasion of A549 cells. We here explored the dose- and time-response of STAT3 to radiation and the effect of radiation on upstream signaling molecules. Materials and Methods: A549 cells were irradiated with different doses of ${\gamma}$-rays. The expression of and nucleus translocation of p-STAT3 in A549 cells were detected by immunoblotting and immunofluorescence, respectively. The level of phosphorylated EGFR was also assessed by immunoblotting, and IL-6 expression was detected by real time PCR and ELISA. Results: Radiation promoted the phosphorylation of STAT3 at Y705 in a dose- and time-dependent manner and nuclear translocation. The level of phosphorylated EGFR in A549 cells increased after radiation. In additional, the mRNA and protein levels of IL-6 in A549 cells were also up regulated by radiation. Conclusions: STAT3 is activated by radiation in a dose-and time-dependent manner, probably due to radiation-induced activation of EGFR or secretion of IL-6 in A549 cells.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5455-5461
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• 2014

Background: Saponins are a major active component for the traditional Chinese medicine, Rubus parvifolius L., which has shown clear antitumor activities. However, the specific effects and mechanisms of saponins of Rubus parvifolius L. (SRP) remain unclear with regard to human chronic myeloid leukemia cells. The aim of this study was to investigate inhibition of proliferation and apoptosis induction effects of SRP in K562 cells and further elucidate its regulatory mechanisms. Materials and Methods: K562 cells were treated with different concentrations of SRP and MTT assays were performed to determine cell viability. Apoptosis induction by SRP was determined with FACS and DAPI staining analysis. Western blotting was used to detect expression of apoptosis and survival related genes. Specific inhibitors were added to confirm roles of STAT3 and AMPK pathways in SRP induction of apoptosis. Results: Our results indicated that SRP exhibited obvious inhibitory effects on the growth of K562 cells, and significantly induced apoptosis. Cleavage of pro-apoptotic proteins was dramatically increased after SRP exposure. SRP treatment also increased the activities of AMPK and JNK pathways, and inhibited the phosphorylation expression level of STAT3 in K562 cells. Inhibition of the AMPK pathway blocked the activation of JNK by SRP, indicating that SRP regulated the expression of JNK dependent oon the AMPK pathway. Furthermore, inhibition of the latter significantly conferred resistance to SRP pro-apoptotic activity, suggesting involvement of the AMPK pathway in induction of apoptosis. Pretreatment with a STAT3 inhibitor also augmented SRP induced growth inhibition and cell apoptosis, further confirming roles of the STAT3 pathway after SRP treatment. Conclusions: Our results demonstrated that SRP induce cell apoptosis through AMPK activation and STAT3 inhibition in K562 cells. This suggests the possibility of further developing SRP as an alternative treatment option, or perhaps using it as adjuvant chemotherapeutic agent for chronic myeloid leukemia therapy.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.279-284
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• 1998

Deep hypothermic circulatory arrest(DHCA), in which systemic temperatures of 2$0^{\circ}C$ or less are used to allow temporary cessation of the circulation, is an useful adjunct in cardiac surgery. Because man in natural circumstances is never exposed to the extreme hypothermic condition, however, one of the controversial aspects is appropriate blood gas management($\alpha$STAT versus PH-STAT) during DHCA. This study aims to compare $\alpha$STAT with PH-STAT management for control of blood gases in experimental cardiopulmonary bypass(CPB) circuits with a membrane oxygenator. Fourteen young pigs were assigned to one of two strategies of gas manipulation. After a median sternotomy, CPB was established. Core cooling was initiated and continued until nasopharyngeal temperature fell below 2$0^{\circ}C$. The flow rate was set at 2,500 ml/min. Once their temperatures were below 2$0^{\circ}C$, the animals were subjected to circulatory arrest for 40mins. During cooling, blood gas was maintained according to either $\alpha$$\alpha$STAT or pH-STAT strategies. After DHCA, the body was rewarmed to normal body temperature. Arterial blood gases were measured before the onset of CPB, before cooling, before DHCA, at the point of 27$^{\circ}C$ during re-warming, on completion of re-warming. Cooling time was significantly shorter in $\alpha$-STAT than PH-STAT strategy, while there was no significant differences in rewarming time between two groups. Carbon dioxide was added between 5.5 and 3.0% in PH-STAT, while no carbon dioxide was added in $\alpha$STAT management. Amounts of oxygen administration were gradually lowered as temperature decreased. In this way, criteria of PH, PaCO, and PaO adjustments were satisfied in both $\alpha$STAT and PH-STAT management groups.

• Parasites, Hosts and Diseases
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• v.54 no.1
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• pp.31-38
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• 2016

Specific gene expressions of host cells by spontaneous STAT6 phosphorylation are major strategy for the survival of intracellular Toxoplasma gondii against parasiticidal events through STAT1 phosphorylation by infection provoked $IFN-{\gamma}$. We determined the effects of small molecules of tyrosine kinase inhibitors (TKIs) on the growth of T. gondii and on the relationship with STAT1 and STAT6 phosphorylation in ARPE-19 cells. We counted the number of T. gondii RH tachyzoites per parasitophorous vacuolar membrane (PVM) after treatment with TKIs at 12-hr intervals for 72 hr. The change of STAT6 phosphorylation was assessed via western blot and immunofluorescence assay. Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, $5{\mu}M$) inhibited 98.0% of the growth of T. gondii, which was comparable to pyrimethamine ($5{\mu}M$) at 96.9% and followed by Erlotinib (ErbB1/EGFR inhibitor, $20{\mu}M$) at 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, $10{\mu}M$) at 21.3%. In the early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibited the phosphorylation of STAT6 in western blot and immunofluorescence assay. Both JAK1 and JAK3, the upper hierarchical kinases of cytokine signaling, were strongly phosphorylated at 2 hr and then disappeared entirely after 4 hr. Some TKIs, especially the EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of the direct phosphorylation of STAT6 by T. gondii.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8405-8410
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• 2016

Hepatitis B virus (HBV) infection is the leading cause of hepatocellular carcinoma (HCC) development. Recent studies demonstrated that single nucleotide polymorphisms (SNPs) rs2293152 in signal transducer and activator of transcription 3 (STAT3) and rs7574865 in signal transducer and activator of transcription 4 (STAT4) are associated with chronic hepatitis B (CHB)-related HCC in the Chinese population. We hypothesized that these polymorphisms might be related to HCC susceptibility in Thai population as well. Study subjects were divided into 3 groups consisting of CHB-related HCC (n=192), CHB without HCC (n=200) and healthy controls (n=190). The studied SNPs were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results showed that the distribution of different genotypes for both polymorphisms were in Hardy-Weinberg equilibrium (P>0.05). Our data demonstrated positive association of rs7574865 with HCC risk when compared to healthy controls under an additive model (GG versus TT: odds ratio (OR)=2.07, 95% confidence interval (CI)=1.06-4.03, P=0.033). This correlation remained significant under allelic and recessive models (OR=1.46, 95% CI=1.09-1.96, P=0.012 and OR=1.71, 95% CI=1.13-2.59, P=0.011, respectively). However, no significant association between rs2293152 and HCC development was observed. These data suggest that SNP rs7574865 in STAT4 might contribute to progression to HCC in the Thai population.

• Parasites, Hosts and Diseases
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• v.62 no.1
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• pp.30-41
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• 2024

The dense granule protein of Toxoplasma gondii, inhibitor of signal transducer and activator of transcription 1 (IST) is an inhibitor of signal transducer and activator of transcription 1 (STAT1) transcriptional activity that binds to STAT1 and regulates the expression of inflammatory molecules in host cells. A sterile inflammatory liver injury in pathological acute liver failures occurs when excessive innate immune function, such as the massive release of IFN-γ and TNF-α, is activated without infection. In relation to inflammatory liver injury, we hypothesized that Toxoplasma gondii inhibitor of STAT1 transcription (TgIST) can inhibit the inflammatory response induced by activating the STAT1/IRF-1 mechanism in liver inflammation. This study used IFN-γ and TNF-α as inflammatory inducers at the cellular level of murine hepatocytes (Hepa-1c1c7) to determine whether TgIST inhibits the STAT1/IRF-1 axis. In stable cells transfected with TgIST, STAT1 expression decreased with a decrease in interferon regulatory factor (IRF)-1 levels. Furthermore, STAT1 inhibition of TgIST resulted in lower levels of NF-κB and COX2, as well as significantly lower levels of class II transactivator (CIITA), iNOS, and chemokines (CLXCL9/10/11). TgIST also significantly reduced the expression of hepatocyte proapoptotic markers (Caspase3/8/9, P53, and BAX), which are linked to sterile inflammatory liver injury. TgIST also reduced the expression of adhesion (ICAM-1 and VCAM-1) and infiltration markers of programmed death-ligand 1 (PD-L1) induced by hepatocyte and tissue damage. TgIST restored the cell apoptosis induced by IFN-γ/TNF-α stimulation. These results suggest that TgIST can inhibit STAT1-mediated inflammatory and apoptotic responses in hepatocytes stimulated with proinflammatory cytokines.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.856-862
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• 2019

A series of thienopyrimidine compounds (6Aa-g and 6Ba-d) were synthesized and characterized by NMR spectroscopy and mass spectrometry. These compounds (6Aa-g and 6Ba-d) potently inhibited STAT3 expression induced by IL-6 in a dose-dependent manner with $IC_{50}$ values of $5.73-0.32{\mu}M$. Among the prepared thienopyrimidine derivatives, 6Aa, 6Ab, 6Ba and 6Bc significantly suppressed the phosphorylation of STAT3 and ERK1/2 stimulated by IL-6 in Hep3B cells. Furthermore, the synthesized compounds might be useful remedies for the treatment of inflammatory diseases by inhibiting the action of IL-6.

• IMMUNE NETWORK
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• v.3 no.3
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• pp.248-254
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• 2003

Oral administration of antigen has long been used in the induction of immune tolerance in various animal models of autoimmune diseases including rheumatoid arthritis (RA). Alleveation of arthritogenic symptoms has been reported from RA patients who received oral administration of type II collagen (CII) without side effects, however its rather inconsistent therapeutic efficacy and variation among patients calls for more detailed investigation on the mechanism of oral tolerance to be settled as regular treatment for RA. In an attempt to understand the immunogenic processes underpinning tolerance induction by orally administered CII, we analyzed changes in the expression of costimulatory molecules and STAT/SOCS signaling messengers in the mouse model of collagen induced arthritis (CIA). We found thatin the spleen of CIA mice, that has been undergone repeated oral feeding of CII prior to the induction of arthritis, showed increased promortion of CTLA4 expressing lymphocytes than in the spleen of PBS fed control. On the other hand, cells expressing CD28 or ICOS were decreased in the spleen of tolerized mice. Tolerance induction by oral CII administration also enhanced the expression of STAT6 in both RNA and protein level, while not affecting the expression of STAT3. The expression of SOCS3, which hasbeen known to transmit STAT-mediated signals from Th2 type cytokines, remained unchanged in the spleen of tolerized mice. Interestingly transcript of SOCS1, which has been associated with Th1 related pathways, was only visible in the spleen of tolerized but not of control mice, suggesting that as in the case of IL-6 signaling, it may exert a feed back inhibition toward the Th1 type stimulation.