• 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.

• Asian Pacific Journal of Cancer Prevention
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• 제14권12호
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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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• 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.

• 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.

• 생명과학회지
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• 제22권4호
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• pp.492-498
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• 2012

파이토케미칼이 암 세포 성장에 미치는 영향을 확인하기 위하여, 대장암 세포주 HCT116에 네 종류의 파이토케미칼을 각각 25 ${\mu}M$의 농도로 처리하였다. 처리한 파이토케미칼 중 curcumin이 가장 강력하게 세포 성장을 억제하였다. 또한 curcumin은 농도의존적으로 세포 성장을 억제하였다. Curcumin에 의한 대장암 세포주 성장 저해 활성에 대한 분자생물학적 기전을 연구하기 위하여 oligo DNA microarray 실험을 수행하였다. 그 결과, 25 ${\mu}M$ curcumin 처리에 의해 2배 이상 발현이 증가된 유전자 137개, 발현이 감소된 유전자 141개를 선별하였다. 발현이 증가된 유전자 중, 세포사멸과 밀접한 관련이 있는 것으로 알려진 유전자 3개를 선택하여, RT-PCR을 통해 이들 유전자의 발현이 감소됨을 확인하였다. 처리한 파이토케미칼 중 curcumin은 가장 강력한 ATF3의 유도자였으며, 농도의존적으로 ATF3의 발현을 증가시켰다. 흥미롭게도, curcumin에 의한 성장 저해는 ATF3-siRNA에 의한 ATF3 유전자 발현감소에 의해 성장이 회복되었다. 또한, ATF3 유전자의 과대발현 후 발현이 변화되는 유전자를 선별한 결과, 세포사멸과 관련된 많은 유전자들이 증가됨을 확인하였다. 결론적으로, 대장암 세포주에서 curcumin에 의한 항 성장활성에 있어서 ATF3 유전자가 중요한 역할을 할 것으로 생각된다.

• Biomolecules & Therapeutics
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• 제23권2호
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• pp.134-140
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• 2015

Conjugated linoleic acids (CLA) are a family of isomers of linoleic acid. CLA increases growth arrest and apoptosis of human colorectal cancer cells through an isomer-specific manner. ATF3 belongs to the ATF/CREB family of transcription factors and is associated with apoptosis in colorectal cancer. The present study was performed to investigate the molecular mechanism by which t10, c12-CLA stimulates ATF3 expression and apoptosis in human colorectal cancer cells. t10, c12-CLA increased an apoptosis in human colorectal cancer cells in dose dependent manner. t10, c12-CLA induced ATF3 mRNA and luciferase activity of ATF3 promoter in a dose-dependent manner. The responsible region for ATF3 transcriptional activation by t10, c12-CLA is located between -147 and -1850 of ATF3 promoter. mRNA stability of ATF3 was not affected by t10, c12-CLA treatment. t10, c12-CLA increases $GSK3{\beta}$ expression and suppresses IGF-1-stimulated phosphorylation of Akt. The knockdown of ATF3 suppressed expression of $GSK3{\beta}$ and NAG-1 and PARP cleavage. The results suggest that t10, c12-CLA 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.

• 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.

• 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.

• 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.