• 대한수의학회지
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• 제44권2호
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• pp.163-169
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• 2004

To elucidate the molecular mechanisms of autoimmune inflammation in the central nervous system, we examined the expression and localization of STAT1, STAT3, STAT4 and STAT6 molecules during experimental autoimmune encephalomyelitis (EAE) by competitive PCR. In the present study, we quantitated IL-4 and IL-12 p40 mRNA by competitive PCR in the CNS during EAE. IL-4 mRNA was found at early and peak stages. On the other hand, the IL-12 p40 mRNA level reached maximal levels at the peak stage and still found at the recovery stage of the disease. We examined the kinetics of STAT mRNA in the CNS during EAE and demonstrated that STAT1 and STAT4 mRNA reached a maximal level at the peak stage of EAE, whereas STAT3 mRNA level increased gradually to the recovery stage. STAT6 mRNA increased rapidly at the early stage followed by gradual decrease till the recovery stage. Taken together, these findings suggest that STAT4 which was probably activated by IL-12 plays a pro-inflammatory role and that STAT3 which was activated throughout the disease course seems to serve as a transducer of anti-inflammatory signals.

• Asian Pacific Journal of Cancer Prevention
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• 제15권16호
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• pp.6791-6798
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• 2014

Background: To investigate the effect of silibinin on proliferation and apoptosis in human gastric cancer cell line MGC803 and its possible mechanisms. Materials and Methods: Human gastric cancer cell line MGC803 cells were treated with various concentration of silibinin. Cellular viability was assessed by CCK-8 assay andapoptosis and cell cycle distribution by flow cytometry. Protein expression and mRNA of STAT3, and cell cycle and apoptosis regulated genes were detected by Western blotting and real-time polymerase chain reaction, respectively. Results: Silibinin inhibits growth of MGC803 cells in a dose- and time-dependent manner. Silibinin effectively induces apoptosis of MGC803 cells and arrests MGC803 cells in the G2/M phase of the cell cycle, while decreasing the protein expression of p-STAT3, and of STAT3 downstream target genes including Mcl-1, Bcl-xL, survivin at both protein and mRNA levels. In addition, silibinin caused an increase in caspase 3 and caspase 9 protein as well as mRNA levels. Silibinin caused G2/M phage arrest accompanied by a decrease in CDK1 and Cyclin B1 at protein and mRNA levels.. Conclusions: These results suggest that silibinin inhibits the proliferation of MGC803 cells, and it induces apoptosis and causes cell cycle arrest by down-regulating CDK1, cyclinB1, survivin, Bcl-xl, Mcl-1 and activating caspase 3 and caspase 9, potentially via the STAT3 pathway.

• 생명과학회지
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• 제21권1호
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• pp.141-145
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• 2011

본 연구에서는 전사억제제(transcriptional inhibitor)로 알려진 actinomycin D가 전사조절인자(transcription factor)인 STAT의 인산화를 유도한다는 것을 확인하였다. Actinomycin D 처리 시 STAT1의 Tyr701, Ser727 인산화는 유도되지 않았지만 STAT3의 Tyr705 잔기의 인산화를 특이적으로 유도하는 것을 확인하였다. Actinomycin D에 의한 STAT3의 Tyr705 인산화 유도가 어떠한 기전을 통한 것인지 확인하기 위해서 관련 인자의 단백질 및 mRNA 발현을 확인한 결과 SOCS3의 단백질 및 mRNA 발현의 감소를 확인하였다. STAT3의 탈인산화를 유도한다고 알려진 tyrosine phosphatase인 SHP-1와 STAT의 upstream kinase인 JAK2의 인산화는 변화가 없었다. 또한 actinomycin D 뿐 아니라 다른 전사억제제인 DRB를 처리 하였을 경우에도 STAT3의 Tyr705 인산화가 유도되는 것을 확인하였다. 이상의 결과는 전사억제제에 의하여 특이적인 SOCS3 단백질 발현감소는 SOCS3의 하류의 target인 STAT3 인산화를 유도하였다.

• 대한한방내과학회지
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• 제26권1호
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• pp.74-92
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• 2005

Objectives/Methods : To analyze the effect of Injinchunggantang(IJCGT) to Interferon-${\alpha}/{\beta}$ signal transmission system in HepG2 cells, HepG2 Cell were treated with IJCGT. Also, revelation of MxA, 2'5'-OAS mRNA leaded by Interferon-${\alpha}/{\beta}$ and revelation and activation of Jak1, TYK1, and STAT 1, all main signal transmission factors, were analyzed. Results : The analysis resulted in the following 1. With interferon ${\alpha}/{\beta}$ there was no affect cell propagation of Hep G2 cells. With IJCGT alone, cell propagation of HepG2 was promoted, and cell propagation control function was recovered. 2. With interferon ${\alpha}/{\beta}$ cell death was unaffected. With IJCGT apoptosis of HepG2 cell was restrained, and the cell's reaction to interferon was unaffected. 3. With interferon ${\alpha}/{\beta}$ treatment mRNA revelation of MxA and 2'5'-OAS was induced. When HepG2 cells were injected with IJCGT without interferon ${\alpha}/{\beta}$ treatment, mRNA revelation of MxA and 2'5'-OAS increased in proportion to the treatment density. With pre-treatment of IJCGT, leaded with interferon ${\alpha}/{\beta}$, promoted revelation of MxA, 2'5' -OAS mRNA. 4. Though mRNA revelation of lakl, TYK1 and STAT1 was unaffected with IJCGT, activation of STAT1 was promoted with an increase of phosphorylation of STAT1 protein. With pre-treatment of IJCGT, Jak1, TYK2, STAT1 phosphorylation, leaded with interferon, strengthened. 5. TNF-a, IL-1b and LPS present, revelation of MxA and 2'5'-OAS mRNA leaded by interferon was restrained when HepG2 cells were treated with IJCGT, and the interferon signal transmission system restraint action leaded by inflammatory cytokines was moderated. Conclusion : These results support a role for IJGCT in promotion of anti-virus action through maintainance of the liver's sensibility toward interferon. A clinical study of an interferon treated patient treated also with IJGCT is needed to determine its efficacy.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.551-560
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• 2014

Colorectal cancer (CRC) is the third most common malignancy and fourth most common cause of cancer mortality worldwide. Untreated chronic inflammation in the intestine ranks among the top three high-risk conditions for colitis-associated colorectal cancer (CAC). Signal Transducer and Activator of Transcription 3 (STAT3) protein is a member of the STAT family of transcription factors often deregulated in CRC. In this review, we try to emphasize the critical role of STAT3 in CAC as well as the crosstalk of STAT3 with inflammatory cytokines, nuclear factor (NF)-${\kappa}B$, PI3K/Akt, Mammalian Target of Rapamycin (mTOR), Notch, $Wnt/{\beta}$-catenin and microRNA (MiR) pathways. STAT3 is considered as a primary drug target to treat CAC in humans and rodents. Also we updated the findings for inhibitors of STAT3 with regard to effects on tumorigenesis. This review will hopefully provide insights on the use of STAT3 as a therapeutic target in CAC.

• BMB Reports
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• 제35권6호
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• pp.583-589
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• 2002

The signal transducer and activator of transcription (STAT)1 is a cytoplasmic-transcription factor that is phosphorylated by Janus kinases (Jak) in response to interferon $\gamma$ (IFN-$\gamma$). The phosphorylated STAT1 translocates to the nucleus, where it turns on specific sets of IFN-$\gamma$-inducible genes, such as the interferon regulatory factor (IRF)-1. We show here that gamma irradiation reduces the IFN-$\gamma$ mRNA expression. The inhibition of the STAT1 phosphorylation and the IRF-1 expression by gamma irradiation was also observed. In contrast, the mRNA levels of IL-5 and transcription factor GATA-3 were slightly induced by gamma irradiation when compared to the non-irradiated sample. Furthermore, we detected the inhibition of cell-mediated immunity by gamma irradiation in the allogenic-mixed lymphocytes' reaction (MLR). These results postulate that gamma irradiation induces the polarized-Th2 response and interferes with STAT1 signals, thereby causing the immunosuppression of the Th1 response.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2813-2818
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• 2015

Objective: To investigate the regulatory effect of curcumin on expression of signal transducer and activator of transcription 3 (STAT3) in skin squamous cell carcinoma tissues as well as possible mechanisms of curcumin in prevention and treatment of skin squamous cell carcinoma. Materials and Methods: Highly invasive A431 cells were treated with curcumin at various doses .The cytotoxic effects of treatment with 5, 10, 15, 20, 25, 30, 35, 40 and 50 umol/L curcumin for 24, 48 and 72 hours on A431 cells were measured by MTT assay. The invasion capacity of cells treated with 5, 10 and 15 umol/L curcumin was measured by Transwell test, while adhesive ability was assessed by cell adhesion assay. The effects of 5,10 and 15 umol/L curcumin on expression levels of STAT3 were determined by Western blotting and on transcription levels of STAT3 mRNA by RT-PCR. Results: Treatment with curcumin at a doses of more than 15 umol/L for more than 24 hour inhibited the growth of A431 cells in a time-and dose-dependent fashion (p<0.001). The doses of 15 umol/L and less for 24 hours showed no significant cytotoxic effects on the cells, survival rates being more than 85%.The invasion and adhesive abilities decreased gradually with the increasing curcumin concentration, 15 umol/L exerting the strongest inhibitory effects (p<0.05). Curcumin showed significant dose-dependent inhibitory effects on the transcription level of STAT3 mRNA (p<0.05). Conclusions: Curcumin may reduce the invasive ability of A431 cells by inhibiting the activation of STAT3 signal pathway and expression of STAT3 as a target gene in the pathway.

• Molecules and Cells
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• 제43권9호
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• pp.793-803
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• 2020

Myeloid-derived suppressor cells (MDSCs) promote tumour progression by contributing to angiogenesis, immunosuppression, and immunotherapy resistance. Although recent studies have shown that microRNAs (miRNAs) can promote the expansion of MDSCs in the tumour environment, the mechanisms involved in this process are largely unknown. Here, we report that microRNA 449c (miR-449c) expression was upregulated in myeloid progenitor cells upon activation of C-X-C motif chemokine receptor 2 (CXCR2) under tumour conditions. MiR-449c upregulation increased the generation of monocytic MDSCs (mo-MDSCs). The increased expression of miR-449c could target STAT6 mRNA in myeloid progenitor cells to shift the differentiation balance of myeloid progenitor cells and lead to an enhancement of the mo-MDSCs population in the tumour environment. Thus, our results demonstrate that the miR-449c/STAT6 axis is involved in the expansion of mo-MDSCs from myeloid progenitor cells upon activation of CXCR2, and thus, inhibition of miR-449c/STAT6 signalling may help to attenuate tumour progression.

• 생명과학회지
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• 제32권2호
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• pp.125-134
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• 2022

본 연구는 노니(Morinda citrifolia)에 함유된 주요 생리활성물질이 RAW 264.7 세포에서 JAK/STAT 신호전달 경로를 통하여 항염증 작용에 관여하는 것을 조사하였다. 건조된 M. citrifolia 열매의 MeOH 추출에 의한 유기용매의 순차 분획에서 얻은 EtOAc 분획물(Mc-EtOAc)에서 가장 높은 항산화 활성을 확인하였고, H₂O₂로 유도된 RAW 264.7 세포의 산화적 스트레스에 대한 세포보호 효과는 처리 농도의존적으로 세포독성을 차단하였다. LPS 처리로 71.6%의 RAW 264.7 세포 생존율에서 240 ㎍/ml의 Mc-EtOAc를 전처리한 군에서 84.5%의 세포 생존율 증가를 보였다. LPS로 유도된 RAW 264.7 세포의 NO 생성 저해활성은 240 ㎍/ml의 Mc-EtOAc에서 양성 대조군의 절반 수준으로 NO의 생성양을 감소시켰다. Mc-EtOAc 처리로 iNOS의 발현량은 농도의존적으로 유의하게 감소하였고, COX-2의 발현은 LPS 유도로 3배 정도로 증가되었으나, 120, 240 ㎍/ml의 Mc-EtOAc를 전처리시 농도의존적으로 유의하게 감소시켰다. 또한 pro-inflammatory cytokine IL-1β와 TNF-α의 mRNA 발현도 억제하였다. 이러한 Mc-EtOAc의 항염증 작용이 상위 신호전달 경로인 JAK/STAT 신호전달 경로 통해 일어나지를 조사한 결과, Mc-EtOAc의 전처리로 LPS로 유도된 RAW 264.7 세포에서 pJAK1과 pSTAT3의 인산화 정도가 유의성 있게 감소하였다. 따라서 RAW 264.7 세포에서 Mc-EtOAc의 항염증 효과는 JAK1/STAT3 신호전달 경로를 통해 염증반응을 억제하는 것으로 사료된다.

• 대한본초학회지
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• 제27권4호
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• pp.9-16
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• 2012

Objective : Canavalia gladiata DC semen (CGS) have been used to improve hematopoietic activity. In the current study, we investigated whether CGS regulate hemato-potentiating function using hematopoietic stem cells (HSCs) as a testing system. Methods : HSCs isolated from femur in mice with leukopenia and thrombocytopenia induced induced by CTX. Then, Real-time PCR was performed to measure the mRNA expression and hematopoietic related gene (EPO, IL-3, SCF, c-kit, GM-CSF), the phoaphorylation of GATA-1 and STAT-5a/b were observed by ELISA method, and the number of granulocyte erythrocyte monocyte macrophage colony-forming units (CFU-GEMM) and erythroid burst forming units (BFU-E), semisolid clonogenic assay was performed. Result : When HSCs were treated with CGS, the expression of hematopoietic related genes (EPO, IL-3, SCF, c-kit, and GM-CSF) were significantly increased at the levels of mRNA as well as production in HSCs. Additionally, CGS enhanced phosphorylation of STAT-1 and signal transducer and activator of transcription-5a/b (STAT-5a/b) in HSCs. Furthermore, CGS significantly enhanced the growth rate of granulocyte erythrocyte monocyte macrophage colony-forming units (CFU-GEMM) and erythroid burst forming units (BFU-E) in vitro. Conclusion : These result suggest that CGS has hematopoietic enhancement via hematopoietic cytokine-mediated GATA-1/STAT-5a/b pathway.