• Biomolecules & Therapeutics
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• 제25권3호
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• pp.337-343
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• 2017

Kahweol as a coffee-specific diterpene has been reported to induce apoptosis in human cancer cells. Although some molecular targets for kahweol-mediated apoptosis have been elucidated, the further mechanism for apoptotic effect of kahweol is not known. Activating transcription factor 3 (ATF3) has been reported to be associated with apoptosis in colorectal cancer. The present study was performed to investigate the molecular mechanism by which kahweol stimulates ATF3 expression and apoptosis in human colorectal cancer cells. Kahweol increased apoptosis in human colorectal cancer cells. It also increased ATF3 expression through the transcriptional activity. The responsible cis-element for ATF3 transcriptional activation by kahweol was CREB located between -147 to -85 of ATF3 promoter. ATF3 overexpression increased kahweol-mediated cleaved PARP, while ATF3 knockdown attenuated the cleavage of PARP by kahweol. Inhibition of ERK1/2 and $GSK3{\beta}$ blocked kahweol-mediated ATF3 expression. The results suggest that kahweol induces apoptosis through ATF3-mediated pathway in human colorectal cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• 제20권4호
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• pp.415-424
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• 2016

Berberine is an isoquinoline alkaloid found in Rhizoma coptidis, and elicits anti-inflammatory effects through diverse mechanisms. Based on previous reports that activating transcription factor-3 (ATF-3) acts as a negative regulator of LPS signaling, the authors investigated the possible involvement of ATF-3 in the anti-inflammatory effects of berberine. It was found berberine concentration-dependently induced the expressions of ATF-3 at the mRNA and protein levels and concomitantly suppressed the LPS-induced productions of proinflammatory cytokines ($TNF-{\alpha}$, IL-6, and $IL-1{\beta}$). In addition, ATF-3 knockdown abolished the inhibitory effects of berberine on LPS-induced proinflammatory cytokine production, and prevented the berberine-induced suppression of MAPK phosphorylation, but had little effect on AMPK phosphorylation. On the other hand, the effects of berberine, that is, ATF-3 induction, proinflammatory cytokine inhibition, and MAPK inactivation, were prevented by AMPK knockdown, suggesting ATF-3 induction occurs downstream of AMPK activation. The in vivo administration of berberine to mice with LPS-induced endotoxemia increased ATF-3 expression and AMPK phosphorylation in spleen and lung tissues, and concomitantly reduced the plasma and tissue levels of proinflammatory cytokines. These results suggest berberine has an anti-inflammatory effect on macrophages and that this effect is attributable, at least in part, to pathways involving AMPK activation and ATF-3 induction.

• Molecules and Cells
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• 제38권1호
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• pp.58-64
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• 2015

Activating transcription factor-3 (ATF3) acts as a negative regulator of cytokine production during Gram-negative bacterial infection. A recent study reported that ATF3 provides protection from Streptococcus pneumoniae infection by activating cytokines. However, the mechanism by which S. pneumoniae induces ATF3 after infection is still unknown. In this study, we show that ATF3 was upregulated via Toll-like receptor (TLR) pathways in response to S. pneumoniae infection in vitro. Induction was mediated by TLR4 and TLR2, which are in the TLR family. The expression of ATF3 was induced by pneumolysin (PLY), a potent pneumococcal virulence factor, via the TLR4 pathway. Furthermore, ATF3 induction is mediated by p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK). Thus, this study reveals a potential role of PLY in modulating ATF3 expression, which is required for the regulation of immune responses against pneumococcal infection in macrophages.

• 한국자원식물학회지
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• 제29권3호
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• pp.281-288
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• 2016

Apoptosis has been regarded as a therapeutic target because apoptosis is typically disturbed in human cancer. Silymarin found in the seeds of the milk thistle (Silybum marianum) has been reported to exert anti-cancer properties through apoptosis. This study was performed to investigate the molecular target for silymarin-mediated apoptosis in human colorectal cancer cells. Silymarin reduced the cell viability and induced an apoptosis in human colorectal cancer cells. ATF3 overexpression increased PARP cleavage by silymarin. Increased ATF3 expression in both protein and mRNA was observed in silymarin-treated cells. In addition, silymarin increased the luciferase activity of ATF3 promoter. Inhibition of JNK and IκK-α blocked silymarin-mediated ATF3 expression. The results suggest that silymarin induces apoptosis through JNK and IκKα-dependent ATF3 expression in human colorectal cancer cells.

• Biomolecules & Therapeutics
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• 제24권2호
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• pp.140-146
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• 2016

Naringenin (NAR) as one of the flavonoids observed in grapefruit has been reported to exhibit an anti-cancer activity. Activating transcription factor 3 (ATF3) is associated with apoptosis in human colon cancer cells. This study was performed to investigate the molecular mechanism by which NAR stimulates ATF3 expression and apoptosis in human colon cancer cells. NAR reduced the cell viability and induced an apoptosis in human colon cancer cells. ATF3 overexpression increased NAR-mediated cleaved PARP, while ATF3 knockdown attenuated the cleavage of PARP by NAR. NAR increased ATF3 expression in both protein and mRNA level, and increased the luciferase activity of ATF3 promoter in a dose-dependent manner. The responsible region for ATF3 transcriptional activation by NAR is located between -317 and -148 of ATF3 promoter. p38 inhibition blocked NAR-mediated ATF3 expression, its promoter activation and apoptosis. The results suggest that NAR induces apoptosis through p38-dependent ATF3 activation in human colon cancer cells.

• 한국자원식물학회지
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• 제28권3호
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• pp.297-304
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• 2015

The flower buds of Sophora japonica L (SF), as a well-known traditional Chinese medicinal herb, have been used to treat bleeding-related disorders such as hematochezia, hemorrhoidal bleeding, dysfunctional uterine bleeding, and diarrhea. However, no specific anti-cancer effect and its molecular mechanism of SF have been described. Thus, we performed in vitro study to investigate if treatment of SF affects activating transcription factor 3 (ATF3) expression and ATF3-mediated apoptosis in human colorectal cancer cells. The effects of SF on cell viability and apoptosis were measured by MTT assay and Western blot analysis against cleaved poly (ADP-ribose) polymerase (PARP). ATF3 activation induced by SF was evaluated using Western blot analysis, RT-PCR and ATF3 promoter assay. SF treatment caused decrease of cell viability and increase of apoptosis in a dose-dependent manner in HCT116 and SW480 cells. Exposure of SF activated the levels of ATF3 protein and mRNA via transcriptional regulation in HCT116 and SW480 cells. Inhibition of extracellular signal-regulated kinases (ERK) 1/2 by PD98059 and p38 by SB203580 attenuated SF-induced ATF3 expression and transcriptional activation. Ectopic ATF3 overexpression accelerated SF-induced cleavage of PARP. These findings suggest that SF-mediated apoptosis may be the result of ATF3 expression through ERK1/2 and p38-mediated transcriptional activation.

• The Korean Journal of Physiology and Pharmacology
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• 제26권6호
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• pp.469-478
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• 2022

WNT signaling plays an important role in cardiac development, but abnormal activity is often associated with cardiac hypertrophy, myocardial infarction, remodeling, and heart failure. The effect of WNT signaling on regulation of atrial natriuretic peptide (ANP) secretion is unclear. Therefore, the purpose of this study was to investigate the effect of Wnt agonist 1 (Wnta1) on ANP secretion and mechanical dynamics in beating rat atria. Wnta1 treatment significantly increased atrial ANP secretion and pulse pressure; these effects were blocked by U73122, an antagonist of phospholipase C. U73122 also abolished the effects of Wnta1-mediated upregulation of protein kinase C (PKC) β and γ expression, and the PKC antagonist Go 6983 eliminated Wnta1-induced secretion of ANP. In addition, Wnta1 upregulated levels of phospho-transforming growth factor-β activated kinase 1 (p-TAK1), TAK1 banding 1 (TAB1) and phospho-activating transcription factor 2 (p-ATF2); these effects were blocked by both U73122 and Go 6983. Wnta1-induced ATF2 was abrogated by inhibition of TAK1. Furthermore, Wnta1 upregulated the expression of T cell factor (TCF) 3, TCF4, and lymphoid enhancer factor 1 (LEF1), and these effects were blocked by U73122 and Go 6983. Tak1 inhibition abolished the Wnta1-induced expression of TCF3, TCF4, and LEF1 and Wnta1-mediated ANP secretion and changes in mechanical dynamics. These results suggest that Wnta1 increased the secretion of ANP and mechanical dynamics in beating rat atria by activation of PKC-TAK1-ATF2-TCF3/LEF1 and TCF4/LEF1 signaling mainly via the WNT/Ca²⁺ pathway. It is also suggested that WNT-ANP signaling is implicated in cardiac physiology and pathophysiology.

• 생명과학회지
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• 제28권1호
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• pp.37-42
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• 2018

NAG-1 단백질은 TGF-${\beta}$ superfamily 유전자로서 암세포의 apoptosis를 유도하고 항암 활성과 관련이 있는 것으로 알려져 있다. 본 연구에서는 프로폴리스 유래의 파이토케미칼 CAPE (caffeic acid phenethyl ester)에 의한 항암유전자 NAG-1의 발현과 발현조절에 대해 연구하였다. 인간 대장암 세포주 HCT116에서 CAPE의 처리에 의해 농도의존적, 시간의존적으로 NAG-1의 발현이 증가됨을 확인하였다. 게다가, 다른 대장암 세포주인 LOVO 세포주에서도 농도의존적으로 NAG-1의 발현이 증가됨을 확인하였다. p53-null HCT116세포주를 이용한 실험에서 CAPE에 의한 NAG-1의 발현은 전사조절인자인 p53에 의존하지 않음을 증명하였다. 또한, 3가지 종류의 NAG-1 프로모터 construct를 이용한 실험에서, cis-element 후보가 -474와 -1,086사이에 있음을 증명하였다. CAPE에 의해 전사조절인자인 ATF3와 CREB의 발현이 변화되는 지를 확인한 결과, CREB은 전혀 발현이 증가되지 않는 반면 ATF3는 CAPE 처리에 의해 농도의존적으로 발현이 증가함을 확인하였다. 그리고, pCG-ATF3와 pCREB의 cotransfection 실험에서 CREB은 NAG-1의 발현에 영향을 못 미치는 반면, ATF3의 과대발현에 의해 NAG-1의 발현이 증가됨을 확인하였다. 결론적으로, CAPE에 의한 NAG-1의 발현은 주로 전사조절인자인 ATF3를 경유하여 일어남을 시사한다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.1053-1057
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• 2012

Objective: Identifying cancer-related genes or proteins is critical in preventing and controlling colorectal cancer (CRC). This study was to investigate the clinicopathological and prognostic value of activating transcription factor 1 (ATF1) in CRC. Methods: Protein expression of ATF1 was detected using immunohistochemistry in 66 CRC tissues. Clinicopathological association of ATF1 in CRC was analyzed with chi-square test or Fisher's exact test. The prognostic value of ATF1 in CRC is estimated using the Kaplan-Meier analysis and Cox regression models. Results: The ATF1 protein expression was significantly lower in tumor tissues than corresponding normal tissues (51.5% and 71.1%, respectively, P = 0.038). No correlation was found between ATF1 expression and the investigated clinicopathological parameters, including gender, age, depth of invasion, lymph node status, metastasis, pathological stage, vascular tumoral emboli, peritumoral deposits, chemotherapy and original tumor site (all with P > 0.05). Patients with higher ATF1 expression levels have a significantly higher survival rate than that with lower expression (P = 0.026 for overall survival, P = 0.008 for progress free survival). Multivariate Cox regression model revealed that ATF1 expression and depth of invasion were the predictors of the overall survival (P = 0.008 and P = 0.028) and progress free survival (P = 0.002 and P = 0.005) in CRC. Conclusions: Higher ATF1 expression is a predictor of a favorable outcome for the overall survival and progress free survival in CRC.

• Journal of Microbiology and Biotechnology
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• 제32권4호
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• pp.493-503
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• 2022

Forkhead transcription factor 3a (Foxo3a) is believed to be a tumor suppressor as its inactivation leads to cell transformation and tumor development. However, further investigation is required regarding the involvement of the activating transcription factor 3 (ATF3)-mediated Tat-interactive protein 60 (Tip60)/Foxo3a pathway in cancer cell apoptosis. This study demonstrated that Chelidonium majus upregulated the expression of ATF3 and Tip60 and promoted Foxo3a nuclear translocation, ultimately increasing the level of Bcl-2-associated X protein (Bax) protein. ATF3 overexpression stimulated Tip60 expression, while ATF3 inhibition by siRNA repressed Tip60 expression. Furthermore, siRNA-mediated Tip60 inhibition significantly promoted Foxo3a phosphorylation, leading to blockade of Foxo3a translocation into the nucleus. Thus, we were able to deduce that ATF3 mediates the regulation of Foxo3a by Tip60. Moreover, siRNA-mediated Foxo3a inhibition suppressed the expression of Bax and subsequent apoptosis. Taken together, our data demonstrate that Chelidonium majus induces SKOV-3 cell death by increasing ATF3 levels and its downstream proteins Tip60 and Foxo3a. This suggests a potential therapeutic role of Chelidonium majus against ovarian cancer.