Increased Expression of FosB through Reactive Oxygen Species Accumulation Functions as Pro-Apoptotic Protein in Piperlongumine Treated MCF7 Breast Cancer Cells
Jin-Ah Park, Han-Heom Na, Hyeon-Ok Jin, and Keun-Cheol Kim
Abstract
Piperlongumine (PL), a natural alkaloid compound isolated from long pepper (Piper longum), can selectively kill cancer cells, but not normal cells, by accumulation of reactive oxygen species (ROS). The objective of this study was to investigate functional roles of expression of SETDB1 and FosB during PL treatment in MCF7 breast cancer cells. PL downregulates SETDB1 expression, and decreased SETDB1 expression enhanced caspase 9 dependent-PARP cleavage during PL-induced cell death. PL treatment generated ROS. ROS inhibitor NAC (N-acetyl cysteine) recovered SETDB1 expression decreased by PL. Decreased SETDB1 expression induced transcriptional activity of FosB during PL treatment. PARP cleavage and positive annexin V level were increased during PL treatment with FosB overexpression whereas PARP cleavage and positive annexin V level were decreased during PL treatment with siFosB transfection, implying that FosB might be a pro-apoptotic protein for induction of cell death in PL-treated MCF7 breast cancer cells. PL induced cell death in A549 lung cancer cells, but molecular changes involved in the induction of these cell deaths might be different. These results suggest that SETDB1 mediated FosB expression may induce cell death in PL-treated MCF7 breast cancer cells.
INTRODUCTION
Piperlongumine (PL) is a natural alkaloid compound isolated from long pepper (Piper longum). PL can enhance the accumulation of reactive oxygen species (ROS) and induce cell death in colon, bladder, breast, pancreatic, osteosarcoma, and lung cancers. This compound can selectively kill cancer cells, but not normal cells (Raj et al., 2011). Many genes are regulated during induction of cell death by PL treatment. PL treatment can decrease expression level of protein regulator of cytokinesis 1 (PRC1) in gastric carcinomas. PRC1 is known to play key roles in microtubule organization in eukaryotes (Zhang et al., 2017). PL can activate CHOP mediated up-regulation of DR5 which potentiates TRAIL-induced cell death in breast cancer (Jin et al., 2014). It is known to down-regulate the expression of HER family receptors in breast cancer cells (Jin et al., 2017). PL can also inhibit transforming growth factor (TGF)-β-induced epithelial-to-mesenchymal transition by modulating the expression of E-cadherin, Snail1, and Twist1 (Park et al., 2017).
SETDB1, a histone methyltransferase, is involved in tri-methylation of histone H3 (H3K9me3) in variety of cancers (Yang et al., 2002). SETDB1 is abnormally expressed in various human cancers. It contributes to tumor growth and metastasis (Xiao et al., 2018). Dysregulation of SETDB1 expression is involved in melanoma, lung cancer, ovarian cancer, breast cancer, implying that SETDB1 might contribute to tumor growth and metastasis (Regina et al., 2016). Under hypoxic conditions, H3K9me3 by SETDB1 can repress expression of ATM and p53-Associated KZNF Protein/ZNF420 (APAK), a negative regulator of p53, in oxygen-dependent but HIF-1-independent manner (Olcina et al., 2016). Increased H3K9me3 by SETDB1 is altered in stress response such as early multi-drug tolerance (Al Emran et al., 2018). SETDB1 can repress SNAIL1-mediated gene reprogramming during TGF-β-induced EMT, indicating balancing function of SETDB1 (Du et al., 2018). SETDB1 expression can be decreased by various anticancer drugs such as doxorubicin and taxol in A549 human lung cancer cells. Its decreased expression is tightly connected with increased FosB gene expression (Lee and Kim, 2013). FosB belongs to Fos family that can dimerize with proteins of the JUN family, thereby forming transcription factor complex AP-1 (Barrett et al., 2017). ΔFosB, a truncated variant of FosB, has been well-studied in the development of addiction-related neuroplasticity or increased sensitivity to behavioral effects of drug abuse (Gajewski et al., 2016). However, functional roles of full length FosB are not well known yet.
Our previous studies have suggested that increased FosB expression can induce cell migration and transforming activity in A549 cells, suggesting that functional role of FosB expression may be connected with resistance to cell death during treatment with anticancer drugs (Na et al., 2016). However, this phenomenon is only studied in A549 lung cancer cells after treatment with anticancer drugs.
In this study, we treated MCF7 breast cancer cells with natural alkaloid compound PL to investigate functional roles of SETDB1 and FosB expression. Results showed that change of SETDB1 and FosB expression might be required for the induction of cell death in PL-treated MCF7 breast cancer cells.
MATERIALS AND METHODS
Cell culture and reagents
Breast cancer cell line MCF7 was obtained from American Type Culture Collection (USA). MCF7 cells were cultured in DMEM medium (Welgene, Korea) containing 10% fetal bovine serum (Invitrogen, USA). A549 human lung cancer cell line was purchased from the Korean Cell Line Bank. Cells were cultured in RPMI 1640 containing 10% fetal bovine serum in a humidified incubator at 37°C. PL, N-acetyl cysteine (NAC), and dimethyl thiozolyl-2′,5′-diphenyl-2-H-tetrazolium bromide (MTT) were purchased from Sigma-Aldrich (USA).
Apoptosis analysis
Apoptosis was analyzed using annexin V-FITC (Biovision, USA) and propidium iodide (PI) staining according to the manufacturer’s instructions. Briefly, MCF7 cells were treated with 10 μM of PL for 24 h. Cells were suspended in 1× binding buffer. Cells were then incubated with 5 μl of Annexin V for 10 min at room temperature in a dark room. PL treated cells were then observed with a confocal microscope at magnification of 20×. For fluorescence-activated cell sorting (FACS) analysis, MCF7 cells were trypsinized and stained with annexin V/PI stating for 10 min at room temperature followed by analysis with a FACSCalibur (Becton-Dickinson, USA).
MTT assay
Cell viability was determined using MTT colorimetric assay to detect viable cells that could convert water-soluble MTT to an insoluble purple formazan. MTT (Sigma-Aldrich) was dissolved in phosphate-buffered saline (PBS) after filtration with a 0.2 μm filter. After transfection with FosB or siFosB in 60 mm dishes, cells were seeded into 96-well plates at density of 2,000 cells/well followed by PL treatment on the next day. Cells were incubated with MTT solution for 2 h at 37°C. The MTT solution was removed and replaced with 100 μl of dimethylsulfoxide to dissolve formazan crystals. Absorbance was measured at wavelength of 570 nm using a microplate reader (Bio-Rad, USA). This experiment was performed in triplicate.
RNA isolation and reverse transcriptase polymerase chain reaction (RT-PCR) analysis
Total RNA was isolated from cells using TRIzol reagent (Invitrogen). cDNA was synthesized with random hexamer from 1 μg of total RNA using M-MLV reverse transcriptase (Enzynomics, Korea). RT-PCR was then performed using cDNA as template with the following gene-specific primers: FosB (sense; 5′-TACTCC ACACCAGGCATGAG-3′ and antisense; 5′-CTTCGTAGGGGATCTTGCAG-3′; 373 bp), SETDB1 (5′-TTAACACAGGCCCTGAATTTCT-3′ and 5′-TACCCCTGTGGGTAGACACTCT-3′; 441 bp) and β-actin (5′-GGATTCCTATGTGGGCGACGA-3′ and 5′-CGCTCGGTGAGGATCTTCATG-3′; 438 bp).
FosB plasmid, siRNA and transfection
FosB plasmid was obtained from Origene (USA) and subcloned into pcDNA3 expression vector. pcDNA3-FosB plasmid was transfected into cells using Lipofectamine 2000 (Invitrogen). SETDB1, FosB, and control siRNAs were purchased from Bioneer (Korea). Transient siRNA transfections were performed using Lipofectamine RNAiMAX (Invitrogen) according to the manufacturer’s instructions.
Western blot analysis
Cells were lysed in lysis buffer supplemented with proteasome inhibitors. Protein concentrations were measured using the Bradford method. Cell lysates were separated via SDS-PAGE and transferred to nitro cellulose membranes followed by immunoblotting with specific primary and horseradish peroxidase-conjugated secondary antibodies. Antibodies specific for SETDB1 (12317) and FosB (11959) were obtained from Abcam (USA). Antibodies for cleaved PARP (9541) and caspase 9 (9502) were obtained from Cell Signaling Technology (USA) and antibody for β-actin (A5316) was obtained from Sigma (USA).
Immunostaining
Cells were washed with cold PBS followed by fixation in 4% paraformaldehyde solution for 10 min at room temperature. After washing with PBS three times, cells were permeabilized with 0.2% Triton X-100 solution for 10 min followed by washing with PBS three times. Blocking was performed using 3% bovine serum albumin in PBS for 1 h followed by incubation with primary antibodies SETDB1 (1:300), FosB (1:300), annexin V (1:100), and caspase 9 (1:50) in 0.03% Triton X-100 at room temperature for 2 h. Cells were then washed with PBS three times followed by incubation with secondary antibodies Alexa 488 goat anti-mouse IgG (1:500; Abcam) and rhodamine goat anti-mouse IgG (1:500; Cell Signaling Technology) in 0.03% Triton X-100. Cells were washed with PBS three times and then stained with DAPI for counter staining. Cells were then washed with PBS three times and mounted with anti-fade reagent.
Measurement of ROS production
Accumulation of ROS was assessed by staining with fluorescent probe 2′-7′-dicholofluorescin diacetate (H2DCFDA) (Thermo Fisher Scientific, USA). Cells were pre-treated with NAC for 1 h followed by treatment with PL for 6 h. After treatment, cells were washed with PBS twice and incubated with 10 μM of H2DCFDA for 30 min in a 5% CO2 incubator. ROS was measured with a FACSCalibur. Images of ROS were acquired for five randomly chosen areas using a confocal microscope (Olympus, Japan).
Luciferase assay
Luciferase vectors for pGL3-FosBp-luc were prepared as described previously (Na and Kim, 2018). MCF7 cells were transfected with luciferase plasmids using Lipofectamine 2000 for 24 h followed by treated with PL for 12 h. Luciferase activity was measured using a Renilla luciferase assay kit (Promega, USA). Luciferase activities were read on a Lumina Glomax 96 microplate luminometer (Promega).
Statistical analysis
All statistical analyses were performed with GraphPad Prism 8 software (GraphPad Software, USA). All values for experiments are presented as mean ± SD. All multiple comparisons were performed using one-way ANOVA followed by Tukey’s post hoc test. P < 0.05 was considered statistically significant. Statistical significance was indicated by *P < 0.05; **P < 0.01; ***P < 0.001; and ns, not significant (P > 0.05).
RESULTS
PL downregulates SETDB1 expression
We investigated whether treatment of PL could change expression levels of SETDB1 in MCF7 breast cancer cells. MCF7 cells were treated with indicated concentration of PL for 24 h. PL decreased SETDB1 mRNA and protein expression in a dose-dependent manner (Fig. 1A). Immunostaining experiment showed that SETDB1 level was gradually decreased by PL treatment (Fig. 1B). To examine the functional significance of decreased expression SETDB1 by PL treatment, we performed transfection of MCF7 cells with siSETDB1 together with PL treatment and examined PARP cleavage using Western blot analysis. PL treatment or siSETDB1 transfection increased PARP cleavage. Cleaved PARP was additively increased after siSETDB1 transfection along with PL treatment (Fig. 1C). MTT assay showed that viability of MCF7 cells was decreased in the group with siSETDB1 transfection along with PL treatment compared to that in PL treated group (Fig. 1D). These data suggest that decreased SETDB1 expression is important for induction of cell death in PL-treated MCF7 breast cancer cells.
SETDB1 expression is regulated by ROS production during PL treatment
To examine a putative relationship of ROS production with decreased SETDB1 expression, we pretreated cells with 10 mM of antioxidant NAC for 1 h followed by PL treatment for 6 h. Fluorescent intensity of H2DCFDA was significantly increased by PL treatment, but completely restored after combinatory treatment with PL and NAC (Fig. 2A). Immunostaining experiment showed that SETDB1 expression decreased by PL was recovered by treatment with NAC and PL, indicating that accumulated ROS could affect SETDB1 expression (Fig. 2B). Moreover, recovery effect of NAC on SETDB1 expression was confirmed using RT-PCR and western blot (Fig. 2C). Interestingly, PARP cleavage induced by PL was reduced by NAC treatment, suggesting that decreased expression of SETDB1 via ROS accumulation was required for the induction of cell death.
SETDB1 mediated FosB expression is regulated by ROS production during PL treatment
SETDB1 directly regulates FosB expression after treatment with various anticancer drugs (Na and Kim, 2018). We performed luciferase assay after transfecting PL-treated MCF7 breast cancer cells with FosB promoter construct. After siSETDB1 transfection or PL treatment, FosB promoter activity in MCF7 cells was increased 3.2-fold or 2.8-fold, respectively. However, combination of siSETDB1 transfection and PL treatment dramatically increased FosB promoter activity up to 9-fold (Fig. 3A). Western blot and RT-PCR analyses showed that FosB expression was increased by transfection of siSETDB1 or the combinatory treatment of PL and siSETDB1, indicating that FoB expression was regulated by SETDB1 (Fig. 3B). In addition, FosB expression increased by PL treatment was restored in MCF7 cells by NAC treatment. These results suggest that SETDB1 mediated FosB expression is regulated by ROS accumulation in PL-treated MCF7 breast cancer cells (Fig. 3C).
FosB overexpression shows synergistic effect for PL-induced cell death
To investigate functional role of FosB during PL-induced cell death in MCF7 breast
cancer cells, we performed extensive cell death assays in PL-treated MCF7 cells along
with transfection of FosB plasmid. MTT assay showed that the combination of PL and
FosB slightly decreased cell viability compared to PL treatment only (Fig. 4A). Western blot analysis showed that FosB overexpression slightly induced PARP cleavage.
Moreover, PARP cleavage was significantly increased in PL treated MCF7 cells after
FosB overexpression, suggesting that FosB expression might be function to mediate
PL-treated cell death in MCF7 human breast cancer cells (Fig. 4B). On the other hand, the group with combination of PL treatment and FosB transfection
showed strong positive annexin V staining (Fig. 4C). We also measured annexin V/PI positive cells using flow cytometry. FosB overexpression
slightly increased annexin V/PI positive cells compare to empty vector transfection,
indicating that FosB expression affect cell death in PL-induced cell death of MCF7
cells. Moreover, Annexin V/PI positive cells were increased in the group with a combination
of PL treatment and FosB overexpression compared to that in the group with PL treatment
along (Fig. 4D). We performed western blot analysis and immunostaining to examine caspases responsible
for PARP cleavage. MCF-7 cells are caspase-3 deficient with a partial deletion in
the CASP-3 gene (Wang et al., 2016). As a result, caspase 9 was increased by FosB overexpression, PL treatment, or combination
of PL and FosB transfection, suggesting that caspase 9 might be a key molecule for
PARP cleavage during PL-treated MCF7 cells (
PL-induced cell death is decreased by siFosB transfection
We also examined effect of siFosB transfection during PL-induced cell death of MCF7
cells. MTT assay showed that siFosB transfection increased cell viability, and then
the combination of PL and siFosB significantly recovered the cell death by PL treatment
only (Fig. 5A). Western blot analysis showed that Combination of PL treatment and siFosB transfection
decreased PARP cleavage compare to PL treatment only (Fig. 5B). Immunostaining of positive annexin V was decreased at the group with combination
of PL treatment and siFosB transfection whereas PL showed strong positive annexin
V staining (Fig. 5C). On the cell sorting experiment for annexin V/PI positive cells using flow cytometry,
annexin V/PI positive cells were decreased in the group with a combination of PL treatment
and siFosB transfection compared to that in the group with PL treatment along (Fig. 5D). On the other hand, Western blot analysis and immunostaining showed that active
caspase 9 by PL treatment was decreased by siFosB transfection, suggesting that activity
of caspase 9 is tightly regulated by FosB during PL induced cell death in MCF7 cells
(
DISCUSSION
Our previous studies have suggested that SETDB1 expression is decreased by DZNep and doxorubicin (Lee and Kim, 2013; Noh et al., 2014). Such decrease of SETDB1 expression is associated with increased FosB gene expression in A549 human cancer cells (Na et al., 2016). In addition, SETDB1 expression is negatively regulated by p53 tumor suppressor during paclitaxel induced-cell death (Noh et al., 2014). Although expression of SETDB1 and FosB is known to be regulated during chemotherapy in human cancer, the molecular mechanism involved in such regulation remains unclear.
In this study, we investigated the functional role of expression of SETDB1 and FosB in MCF7 breast cancer cells during PL treatment. PL induced cell death through ROS accumulation in MCF7 breast cancer cells. It regulated the linked expression of SETDB1 and FosB. Although the regulation of SETDB1 and FosB by anticancer drugs was similar, our data showed that increased FosB expression was associated with increased PARP cleavage and increased annexin V staining in PL-treated MCF7 breast cancer cells (Fig. 4). The present data suggest that decreased SETDB1 expression and the increased FosB expression might be functionally linked to the induction of death in MCF7 breast cancer cells caused by PL treatment.
SETDB1 is known to have oncogenic role in many human cancers, including nasopharyngeal carcinoma (Huang et al., 2018), hepatocellular carcinoma (Wong et al., 2016), non-small cell lung cancer (Sun et al., 2015), and breast cancer (Ryu et al., 2018). Overexpression of SETDB1 promotes metastasis by regulating SMAD7 in TNBC (Ryu et al., 2018). SETDB1 overexpression accelerates tumorigenesis through activation of AKT that functions as an oncogene in ovarian cancer cells (Guo et al., 2019). Silenced SETDB1 can inhibit proliferation, migration, and repress tumor growth by miR-381-3p related regulation (Wu et al., 2018). Therefore, it seems that SETDB1 expression is decreased for inducing cell death during anticancer drug treatment.
FosB expression functionally induced death of MCF7 cells after PL treatment. This was unexpected considering that FosB overexpression was associated with invasion and proliferation of A549 human lung cancer cells (Na et al., 2016). However, FosB expression could be induced by antimicrobial peptide, tilapia piscidin-4 (TP4), via mitochondrial damage-triggered Ca2+ dysregulation, leading to cell death of breast cancers (Ting et al., 2016). Moreover, FosB transcriptionally activates protocadherin-β13 (PCDHB13), which is functionally associated with disruption of microtubules, suggesting that elevated expression of FosB and PCDHB13 induced cell death of NSCLC (Ting et al., 2019). Although the functional role of FosB expression is confusing according to therapeutic drugs, several interpretations may therefore be possible to explain the present study.
A549 and MCF7 cells exhibit significantly different sensitivities to doxorubicin which
has growth inhibitory effect (Ho et al., 2013; Rogalska et al., 2014). ERK pathway is involved in cell proliferation, differentiation, and migration (Dhillon et al., 2007). Doxorubicin regulates expression SETDB1 and FosB through ERK activation while increased
FosB expression is correlated with transforming activity of A549 cells (Na and Kim, 2018). However, PL induced FosB expression via accumulation of ROS in MCF7 breast cancer
cells (Fig. 2). PL can inhibit GSTP1 antioxidant enzyme and show anticancer effects by ROS signaling
(Liu et al., 2013). We also determined whether molecular changes for cell death were necessary for
the induction of cell death at the same concentration of PL in A549 human lung cancer
cells. PL treatment decreased SETDB1 expression. However, such decrease in the expression
of SETDB1 in A549 cells was recovered by NAC (
FosB gene has been ranked in the top ten early response genes with changed expression in human cancer tissues during treatment with anti-cancer drugs (Lopez-Knowles et al., 2015). Early response genes are activated at transcription level in the first round of response to stimuli before synthesis of any new proteins. AP-1 transcription factor that regulates genes is responsible for cell proliferation and apoptosis. ΔFosB overexpression can increase the expression of MMP-9 to induce cellular viability and decrease cell apoptosis in MCF-7 breast cancer cells (Li et al., 2016). FosB siRNA completely abrogated effects of stress on tumor metastasis, indicating that FosB gene expression could have anti-apoptotic function (Shahzad et al., 2010). However, AP-1 subunits show variable expression patterns under hypoxia condition, suggesting that combination of AP-1 hetero dimers might play a role in the decisive phenomenon of cell to choose between proliferation and apoptosis (Yadav et al., 2017). Although increased FosB expression is a common phenomenon during treatment with various anticancer drugs, early response genes by drug sensitivity in different types of cells or different signalling pathway might have functional importance.
Cancer cells cope with homeostatic balances for survival or cell death in response to anticancer drugs (Kim, 2018). Our current data showed that FosB expression might function toward pro-apoptotic mechanism. The oncogenic function of Fos family in human cancers has been extensively studied. However, it was limited to functional studies on c-Fos oncogene (Tkach et al., 2003; Tulchinsky, 2000). Regarding functional differences between Fos family members, FosB might have different functional meaning compared to c-Fos (Tang et al., 2016). Although knowledge on FosB is still incomplete, FosB protein might be specialized to have functions in both survival and death of cancer cells depending on different stimuli. More functional studies on FosB will be needed using various molecular approaches and different types of cancer cells.
Supplementary Material
ACKNOWLEDGMENTS
This work was supported by funds from National Research Foundation of Korea (2016R1D1A3B02006754) and by the Korea Basic Science Institute (KBSI) National Research Facilities & Equipment Center (NFEC) grant (2019R1A6C1010006).
Article information
Articles from Mol. Cells are provided here courtesy of Mol. Cells
References
- Al Emran, A., Marzese, D.M., Menon, D.R., Stark, M.S., Torrano, J., Hammerlindl, H.,
Zhang, G., Brafford, P., Salomon, M.P., and Nelson, N. (2018). Distinct histone modifications
denote early stress-induced drug tolerance in cancer. Oncotarget. 9, 8206-8222.
- Barrett, C.S., Millena, A.C., and Khan, S.A. (2017). TGF-beta effects on prostate
cancer cell migration and invasion require FosB. Prostate. 77, 72-81.
- Dhillon, A.S., Hagan, S., Rath, O., and Kolch, W. (2007). MAP kinase signalling pathways
in cancer. Oncogene. 26, 3279-3290.
- Du, D., Katsuno, Y., Meyer, D., Budi, E.H., Chen, S.H., Koeppen, H., Wang, H., Akhurst,
R.J., and Derynck, R. (2018). Smad3-mediated recruitment of the methyltransferase
SETDB1/ESET controls Snail1 expression and epithelial-mesenchymal transition. EMBO
Rep. 19, 135-155.
- Gajewski, P.A., Turecki, G., and Robison, A.J. (2016). Differential expression of
FosB proteins and potential target genes in select brain regions of addiction and
depression patients. PLoS One. 11, e0160355.
- Guo, J., Dai, X., Laurent, B., Zheng, N., Gan, W., Zhang, J., Guo, A., Yuan, M., Liu,
P., and Asara, J.M. (2019). AKT methylation by SETDB1 promotes AKT kinase activity
and oncogenic functions. Nat Cell Biol. 21, 226-237.
- Ho, Y.F., Karsani, S.A., Yong, W.K., and Abd Malek, S.N. (2013). Induction of apoptosis
and cell cycle blockade by helichrysetin in a549 human lung adenocarcinoma cells.
Evid Based Complement Alternat Med. 2013, 857257.
- Huang, J., Huang, W., Liu, M., Zhu, J., Jiang, D., Xiong, Y., Zhen, Y., Yang, D.,
Chen, Z., and Peng, L. (2018). Enhanced expression of SETDB1 possesses prognostic
value and promotes cell proliferation, migration and invasion in nasopharyngeal carcinoma.
Oncol Rep. 40, 1017-1025.
- Jin, H.O., Lee, Y.H., Park, J.A., Lee, H.N., Kim, J.H., Kim, J.Y., Kim, B., Hong,
S.E., Kim, H.A., and Kim, E.K. (2014). Piperlongumine induces cell death through ROS-mediated
CHOP activation and potentiates TRAIL-induced cell death in breast cancer cells. J
Cancer Res Clin Oncol. 140, 2039-2046.
- Jin, H.O., Park, J.A., Kim, H.A., Chang, Y.H., Hong, Y.J., Park, I.C., and Lee, J.K.
(2017). Piperlongumine downregulates the expression of HER family in breast cancer
cells. Biochem Biophys Res Commun. 486, 1083-1089.
- Kim, J.A. (2018). Cooperative instruction of signaling and metabolic pathways on the
epigenetic landscape. Mol Cells. 41, 264-270.
- Lee, J.K. and Kim, K.C. (2013). DZNep, inhibitor of S-adenosylhomocysteine hydrolase,
down-regulates expression of SETDB1 H3K9me3 HMTase in human lung cancer cells. Biochem
Biophys Res Commun. 438, 647-652.
- Li, H., Li, L., Zheng, H., Yao, X., and Zang, W. (2016). Regulatory effects of DeltaFosB
on proliferation and apoptosis of MCF-7 breast cancer cells. Tumor Biol. 37, 6053-6063.
- Liu, J.M., Pan, F., Li, L., Liu, Q.R., Chen, Y., Xiong, X.X., Cheng, K., Yu, S.B.,
Shi, Z., and Yu, A.C. (2013). Piperlongumine selectively kills glioblastoma multiforme
cells via reactive oxygen species accumulation dependent JNK and p38 activation. Biochem
Biophys Res Commun. 437, 87-93.
- Lopez-Knowles, E., Wilkerson, P.M., Ribas, R., Anderson, H., Mackay, A., Ghazoui,
Z., Rani, A., Osin, P., Nerurkar, A., and Renshaw, L. (2015). Integrative analyses
identify modulators of response to neoadjuvant aromatase inhibitors in patients with
early breast cancer. Breast Cancer Res. 17, 35.
- Na, H.H. and Kim, K.C. (2018). SETDB1-mediated FosB regulation via ERK2 is associated
with an increase in cell invasiveness during anticancer drug treatment of A549 human
lung cancer cells. Biochem Biophys Res Commun. 495, 512-518.
- Na, H.H., Noh, H.J., Cheong, H.M., Kang, Y., and Kim, K.C. (2016). SETDB1 mediated
FosB expression increases the cell proliferation rate during anticancer drug therapy.
BMB Rep. 49, 238-243.
- Noh, H.J., Kim, K.A., and Kim, K.C. (2014). p53 down-regulates SETDB1 gene expression
during paclitaxel induced-cell death. Biochem Biophys Res Commun. 446, 43-48.
- Olcina, M.M., Leszczynska, K.B., Senra, J.M., Isa, N.F., Harada, H., and Hammond,
E.M. (2016). H3K9me3 facilitates hypoxia-induced p53-dependent apoptosis through repression
of APAK. Oncogene. 35, 793-799.
- Park, M.J., Lee, D.E., Shim, M.K., Jang, E.H., Lee, J.K., Jeong, S.Y., and Kim, J.H.
(2017). Piperlongumine inhibits TGF-beta-induced epithelial-to-mesenchymal transition
by modulating the expression of E-cadherin, Snail1, and Twist1. Eur J Pharmacol. 812, 243-249.
- Raj, L., Ide, T., Gurkar, A.U., Foley, M., Schenone, M., Li, X., Tolliday, N.J., Golub,
T.R., Carr, S.A., and Shamji, A.F. (2011). Selective killing of cancer cells by a
small molecule targeting the stress response to ROS. Nature. 475, 231-234.
- Regina, C., Compagnone, M., Peschiaroli, A., Lena, A., Annicchiarico-Petruzzelli,
M., Piro, M.C., Melino, G., and Candi, E. (2016). Setdb1, a novel interactor of DeltaNp63,
is involved in breast tumorigenesis. Oncotarget. 7, 28836-28848.
- Rogalska, A., Szwed, M., and Rychlik, B. (2014). The connection between the toxicity
of anthracyclines and their ability to modulate the P-glycoprotein-mediated transport
in A549, HepG2, and MCF-7 cells. Sci World J. 2014, 819548.
- Ryu, T.Y., Kim, K., Kim, S.K., Oh, J.H., Min, J.K., Jung, C.R., Son, M.Y., Kim, D.S.,
and Cho, H.S. (2018). SETDB1 regulates SMAD7 expression for breast cancer metastasis.
BMB Rep. 52, 139-144.
- Shahzad, M.M., Arevalo, J.M., Armaiz-Pena, G.N., Lu, C., Stone, R.L., Moreno-Smith,
M., Nishimura, M., Lee, J.W., Jennings, N.B., and Bottsford-Miller, J. (2010). Stress
effects on FosB- and interleukin-8 (IL8)-driven ovarian cancer growth and metastasis.
J Biol Chem. 285, 35462-35470.
- Sun, Q.Y., Ding, L.W., Xiao, J.F., Chien, W., Lim, S.L., Hattori, N., Goodglick, L.,
Chia, D., Mah, V., and Alavi, M. (2015). SETDB1 accelerates tumourigenesis by regulating
the WNT signalling pathway. J Pathol. 235, 559-570.
- Tang, C., Jiang, Y., Shao, W., Shi, W., Gao, X., Qin, W., Jiang, T., Wang, F., and
Feng, S. (2016). Abnormal expression of FOSB correlates with tumor progression and
poor survival in patients with gastric cancer. Int J Oncol. 49, 1489-1496.
- Ting, C.H., Chen, Y.C., Wu, C.J., and Chen, J.Y. (2016). Targeting FOSB with a cationic
antimicrobial peptide, TP4, for treatment of triple-negative breast cancer. Oncotarget.
7, 40329-40347.
- Ting, C.H., Lee, K.Y., Wu, S.M., Feng, P.H., Chan, Y.F., Chen, Y.C., and Chen, J.Y.
(2019). FOSB(-)PCDHB13 axis disrupts the microtubule network in non-small cell lung
cancer. Cancers. 11, 107.
- Tkach, V., Tulchinsky, E., Lukanidin, E., Vinson, C., Bock, E., and Berezin, V. (2003).
Role of the Fos family members, c-Fos, Fra-1 and Fra-2, in the regulation of cell
motility. Oncogene. 22, 5045-5054.
- Tulchinsky, E. (2000). Fos family members: regulation, structure and role in oncogenic
transformation. Histol Histopathol. 15, 921-928.
- Wang, S., He, M., Li, L., Liang, Z., Zou, Z., and Tao, A. (2016). Cell-in-cell death
is not restricted by caspase-3 deficiency in MCF-7 cells. J Breast Cancer. 19, 231-241.
- Wong, C.M., Wei, L., Law, C.T., Ho, D.W., Tsang, F.H., Au, S.L., Sze, K.M., Lee, J.M.,
Wong, C.C., and Ng, I.O. (2016). Up-regulation of histone methyltransferase SETDB1
by multiple mechanisms in hepatocellular carcinoma promotes cancer metastasis. Hepatology.
63, 474-487.
- Wu, M., Fan, B., Guo, Q., Li, Y., Chen, R., Lv, N., Diao, Y., and Luo, Y. (2018).
Knockdown of SETDB1 inhibits breast cancer progression by miR-381-3p-related regulation.
Biol Res. 51, 39.
- Xiao, J.F., Sun, Q.Y., Ding, L.W., Chien, W., Liu, X.Y., Mayakonda, A., Jiang, Y.Y.,
Loh, X.Y., Ran, X.B., and Doan, N.B. (2018). The c-MYC-BMI1 axis is essential for
SETDB1-mediated breast tumourigenesis. J Pathol. 246, 89-102.
- Yadav, S., Kalra, N., Ganju, L., and Singh, M. (2017). Activator protein-1 (AP-1):
a bridge between life and death in lung epithelial (A549) cells under hypoxia. Mol
Cell Biochem. 436, 99-110.
- Yang, L., Xia, L., Wu, D.Y., Wang, H., Chansky, H.A., Schubach, W.H., Hickstein, D.D.,
and Zhang, Y. (2002). Molecular cloning of ESET, a novel histone H3-specific methyltransferase
that interacts with ERG transcription factor. Oncogene. 21, 148-152.
- Zhang, B., Shi, X., Xu, G., Kang, W., Zhang, W., Zhang, S., Cao, Y., Qian, L., Zhan,
P., and Yan, H. (2017). Elevated PRC1 in gastric carcinoma exerts oncogenic function
and is targeted by piperlongumine in a p53-dependent manner. J Cell Mol Med. 21, 1329-1341.
