Interleukin-17 induces AP-1 activity and cellular transformation via upregulation of tumor progression locus 2 activity.

Kim, Garam,Khanal, Prem,Lim, Sung-Chul,Yun, Hyo Jeong,Ahn, Sang-Gun,Ki, Sung Hwan,Choi, Hong Seok IRL Press] ; Oxford University Press 2013 Carcinogenesis Vol.34 No.2

<P>Inflammatory conditions elicited by extrinsic environmental factors promote malignant transformation, tumor growth and metastasis. Although the role of T cells in cancer promotion has been examined, little is known about the underlying molecular mechanisms of interleukin-17 A (IL-17A), a proinflammatory cytokine produced by activated CD4(+) memory T cells, in carcinogenesis. Here, we report that IL-17A induces neoplastic transformation of JB6 Cl41 cells through activation of tumor progression locus 2 (TPL2). IL-17A dose- and time-dependently increases TPL2 phosphorylation in JB6 Cl41 cells through IL-17A receptor. IL-17A activates mitogen-activated protein kinase/extracellular signal-regulated kinase kinases, c-jun N-terminal kinases and STAT3 signaling pathways, which are inhibited by a TPL2 kinase inhibitor (TKI). Furthermore, IL-17A activates c-fos and c-jun promoter activity, resulting in increased activator protein-1 (AP-1) activity. When small interfering RNA of IL-17A receptor (IL-17R), IL-17A and TPL2 were introduced into JB6 Cl41 cells, respectively, IL-17A-induced AP-1 activity was significantly decreased compared with control cells. Similarly, TPL2 inhibition suppressed AP-1 activity induced by IL-17A. The knockdown of IL-17R and TKI treatment in JB6 Cl41 cells resulted in decreased IL-17A-induced cell transformation. The in vivo chorioallantoic membrane assay also showed that IL-17A increased tumor formation of JB6 Cl41 cells, whereas TKI inhibited the tumorigenesis promoted by IL-17A. Consistent with these observations, knockdown of IL-17A and/or inhibition of TPL2 attenuated tumorigenicity of human breast cancer MCF7 cells. Together, our findings point to a critical role for the IL-17A-induced TPL2 signaling pathway in supporting cancer-associated inflammation in the tumor microenvironment. Therapeutic approaches that target this pathway may, therefore, effectively inhibit carcinogenesis.</P>

Neuropathogenic role of adenylate kinase-1 in Aβ-mediated tau phosphorylation via AMPK and GSK3β.

Park, Hyejin,Kam, Tae-In,Kim, Youngdoo,Choi, Hyunwoo,Gwon, Youngdae,Kim, Changsoo,Koh, Jae-Young,Jung, Yong-Keun IRL Press ; Oxford University Press 2012 Human Molecular Genetics Vol.21 No.12

<P>Abnormally hyperphosphorylated tau is often caused by tau kinases, such as GSK3β and Cdk5. Such occurrence leads to neurofibrillary tangle formation and neuronal degeneration in tauopathy, including Alzheimer's disease (AD). However, little is known about the signaling cascade underlying the pathologic phosphorylation of tau by Aβ(42). In this study, we show that adenylate kinase 1 (AK1) is a novel regulator of abnormal tau phosphorylation. AK1 expression is markedly increased in the brains of AD patients and AD model mice and is significantly induced by Aβ(42) in the primary neurons. Ectopic expression of AK1 alone augments the pathologic phosphorylation of tau at PHF1, CP13 and AT180 epitopes and enhances the formation of tau aggregates. Inversely, downregulation of AK1 alleviates Aβ(42)-induced hyperphosphorylation of tau. AK1 plays a role in Aβ(42)-induced impairment of AMPK activity and GSK3β activation in the primary neurons. Pharmacologic studies show that treatment with an AMPK inhibitor activates GSK3β, and a GSK3β inhibitor attenuates AK1-mediated tau phosphorylation. In a Drosophila model of human tauopathy, the retinal expression of human AK1 severely exacerbates rough eye phenotype and increases abnormal tau phosphorylation. Further, neural expression of AK1 reduces the lifespan of tau transgenic files. Taken together, these observations indicate that the neuronal expression of AK1 is induced by Aβ(42) to increase abnormal tau phosphorylation via AMPK-GSK3β and contributes to tau-mediated neurodegeneration, providing a new upstream modulator of GSK3β in the pathologic phosphorylation of tau.</P>

Aurora B confers cancer cell resistance to TRAIL-induced apoptosis via phosphorylation of survivin.

Yoon, Mi Jin,Park, Seok Soon,Kang, You Jung,Kim, In Young,Lee, Ju Ahn,Lee, Jong Soo,Kim, Eu-Gene,Lee, Chang-Woo,Choi, Kyeong Sook IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.3

<P>Tumor necrosis factor-related apoptosis-induced ligand (TRAIL) induces apoptosis selectively in cancer cells while sparing normal cells. However, many cancer cells are resistant to TRAIL-induced cell death. In this study, we examined whether Aurora B, which is frequently overexpressed in cancer cells, is associated with TRAIL resistance. The protein levels of Aurora B were higher in TRAIL-resistant cancer cell lines than in TRAIL-sensitive cancer cell lines. Exogenously expressed Aurora B attenuated TRAIL-induced apoptosis in the tested TRAIL-sensitive cancer cell lines, whereas the small interfering RNA-mediated suppression of Aurora B expression stimulated TRAIL-mediated apoptosis in the tested TRAIL-resistant cancer cell lines. Furthermore, combined treatment with TRAIL and ZM447439, a specific inhibitor of Aurora B, synergistically induced apoptosis in various TRAIL-resistant cancer cells, suggesting that this combined regimen may represent an attractive strategy for effectively treating TRAIL-resistant malignant cancers. Mechanistically, the inhibition of Aurora B activity in various cancer cells commonly downregulated survivin protein levels and potentiated the activation of caspase-3. In addition, Aurora B inhibition induced mitotic catastrophe, which also contributed to the sensitization of cells to TRAIL-mediated apoptosis. Interestingly, forced overexpression of Aurora B increased the protein levels of survivin, but not those of a non-phosphorylatable survivin mutant in which threonine 117 was replaced by alanine, indicating that phosphorylation of survivin is required for this effect. Furthermore, TRAIL-induced apoptosis in MDA-MB-435S cells was attenuated by wild-type survivin but not by the non-phosphorylatable survivin mutant. Collectively, our results demonstrate that Aurora B confers TRAIL resistance to cancer cells via phosphorylation of survivin.</P>

Maspin genetically and functionally associates with gastric cancer by regulating cell cycle progression.

Kim, Minjin,Ju, Hyoungseok,Lim, Byungho,Kang, Changwon IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.12

<P>Human SERPINB5, commonly known as maspin, has diverse functions as a tumor suppressor. In this study, we discovered that maspin has a novel role in cell cycle control, and common variants were discovered to be associated with gastric cancer. The genotypes of 836 unrelated Korean participants (including 430 with gastric cancer) were examined for 12 tag single-nucleotide polymorphisms (SNPs) and imputed for 178 SNPs in the maspin gene. Susceptibility to diffuse-type gastric cancer was strongly and significantly associated with several SNPs including rs3744941 (C>T) in the promoter (TT versus CC+CT, odds ratio = 0.56 [0.37-0.83], P = 0.0038) and rs8089104 (C>T) in intron 1 (TT+CT versus CC, odds ratio = 1.7 [1.2-2.5], P = 0.0021). No SNPs were associated with susceptibility to intestinal-type gastric cancer. A haplotype of three highly correlated promoter SNPs associated with higher cancer risk showed 40% of the activity of a non-risk-associated haplotype promoter in the diffuse-type gastric cancer cell line MKN45. Maspin downregulation achieved either by a short hairpin RNA targeting maspin or overexpression of the E2F1-DP1 complex in MKN45 cells dramatically accelerated cell cycle progression and caused an increase of active CDC25C levels and a decrease of inactive CDK1 levels. In contrast, maspin upregulation had the opposite effect, substantially retarding cell proliferation. Therefore, our results suggest that a maspin promoter haplotype that reduces maspin gene expression accelerates cell cycle progression and, consequently, is associated with increased susceptibility to diffuse-type gastric cancer. Furthermore, a novel maspin-related pathway is demonstrated to underlie gastric carcinogenesis.</P>

NDRG2 correlated with favorable recurrence-free survival inhibits metastasis of mouse breast cancer cells via attenuation of active TGF-β production.

Oh, Sang-seok,Kim, Donghyeok,Kim, Dong-Hee,Chang, Hong Hee,Sohn, Kyung-Cheol,Kim, Kyo Hyun,Jung, Sung Hoo,Lee, Byoung Kil,Kim, Joo Heon,Kim, Kwang Dong IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.10

<P>N-myc downstream-regulated gene 2 (NDRG2) has been studied for its inhibitory effects against growth and metastasis of many tumor cell types. In this study, we showed NDRG2 expression was correlated with favorable recurrence-free survival of patients with breast cancer and inhibited metastasis of breast cancer cells (4T1). NDRG2 expression was examined in 189 breast carcinoma tissues and paired normal breast tissues using immunohistochemistry. Histological and clinicopathological data were correlated using Pearson's chi-square test of independence. NDRG2 expression in human breast cancer tissues was inversely associated with lymph node metastasis and pTNM stage. Furthermore, patients with breast cancer with a high level of NDRG2 expression showed favorable recurrence-free survival (P = 0.038). To study the effect of NDRG2 on metastasis in vivo, we established an NDRG2-overexpressing mouse breast cancer cell line (4T1-NDRG2) and measured the metastasis and survival of 4T1-NDRG2 tumor-bearing mice. To test whether transforming growth factor β (TGF-β)- mediated metastasis of 4T1 was inhibited by NDRG2 expression, TGF-Smad-binding element (SBE)-luciferase activity and/or measurement of active TGF-β were performed in cell or tumor tissue level. 4T1-NDRG2 cells grew gradually and showed less metastatic activity in vivo and low invasiveness in vitro. 4T1-NDRG2 cells showed lower SBE-luciferase activity and lower level of active autocrine TGF-β than 4T1-Mock did. Correctly, our data show that NDRG2 significantly suppress tumor metastasis by attenuating active autocrine TGF-β production, and the attenuation might be typically associated with the favorable recurrence-free survival of patients clinically.</P>

The TFG-TEC fusion gene created by the t(3;9) translocation in human extraskeletal myxoid chondrosarcomas encodes a more potent transcriptional activator than TEC.

Lim, Bobae,Jun, Hee Jung,Kim, Ah-young,Kim, Sol,Choi, JeeHyun,Kim, Jungho IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.8

<P>The t(3;9)(q11-q12;q22) translocation associated with human extraskeletal myxoid chondrosarcomas results in a chimeric molecule in which the N-terminal domain (NTD) of the TFG (TRK-fused gene) is fused to the TEC (Translocated in Extraskeletal Chondrosarcoma) gene. Little is known about the biological function of TFG-TEC. Because the NTDs of TFG-TEC and TEC are structurally different, and the TFG itself is a cytoplasmic protein, the functional consequences of this fusion in extraskeletal myxoid chondrosarcomas were examined. The results showed that the chimeric gene encoded a nuclear protein that bound DNA with the same sequence specificity as the parental TEC protein. Comparison of the transactivation properties of TFG-TEC and TEC indicated that the former has higher transactivation activity for a known target reporter containing TEC-binding sites. Additional reporter assays for TFG (NTD) showed that the TGF (NTD) of TFG-TEC induced a 12-fold increase in the activation of luciferase from a reporter plasmid containing GAL4 binding sites when fused to the DNA-binding domain of GAL4, indicating that the TFG (NTD) of the TFG-TEC protein has intrinsic transcriptional activation properties. Finally, deletion analysis of the functional domains of TFG (NTD) indicated that the PB1 (Phox and Bem1p) and SPYGQ-rich region of TFG (NTD) were capable of activating transcription and that full integrity of TFG (NTD) was necessary for full transactivation. These results suggest that the oncogenic effect of the t(3;9) translocation may be due to the TFG-TEC chimeric protein and that fusion of the TFG (NTD) to the TEC protein produces a gain-of-function chimeric product.</P>

Tectorigenin sensitizes paclitaxel-resistant human ovarian cancer cells through downregulation of the Akt and NFκB pathway.

Yang, Yeong-In,Lee, Kyung-Tae,Park, Hee-Juhn,Kim, Tae Jin,Choi, Youn Seok,Shih, Ie-Ming,Choi, Jung-Hye IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.12

<P>Paclitaxel (Taxol) is currently used as the front-line chemotherapeutic agent for several cancers including ovarian carcinoma; however, the drug frequently induces drug resistance through multiple mechanisms. The new strategy of using natural compounds in combination therapies is highly attractive because those compounds may enhance the efficacy of chemotherapy. In this study, we found that tectorigenin, an isoflavonoid isolated from flower of Pueraria thunbergiana, enhanced the growth-inhibitory effect of paclitaxel in paclitaxel-resistant ovarian cancer cells (MPSC1(TR), A2780(TR) and SKOV3(TR)) as well as their naive counterparts. The combination of tectorigenin with paclitaxel resulted in a synergistic apoptosis compared with either agent alone through activation of caspases-3, -8 and -9. Treatment with tectorigenin inhibited the nuclear translocation of NFκB and the expression of NFκB-dependent genes such as FLIP, XIAP, Bcl-2, Bcl-xL and COX-2, which are known to be associated with chemoresistance. In addition, the tectorigenin-paclitaxel combination inhibited the phosphorylation of IκB and IKK and the activation of Akt in paclitaxel-resistant cancer cells. Moreover, tectorigenin-paclitaxel-induced cell growth inhibition was enhanced by pretreatment with the Akt inhibitor LY294002 or overexpression of the dominant negative Akt (Akt-DN), but reduced by overexpression of constitutively activated Akt (Akt-Myr). Furthermore, we found that Akt-Myr, at least in part, reversed tectorigenin-paclitaxel-induced nuclear translocation of NFκB and the phosphorylation of IκB and IKK. These data suggest that tectorigenin could sensitize paclitaxel-resistant human ovarian cancer cells through inactivation of the Akt/IKK/IκB/NFκB signaling pathway, and promise a new intervention to chemosensitize paclitaxel-induced cytotoxicity in ovarian cancer.</P>

Functional invadopodia formation through stabilization of the PDPN transcript by IMP-3 and cancer-stromal crosstalk for PDPN expression.

Hwang, Young Sun,Xianglan, Zhang,Park, Kwang-Kyun,Chung, Won-Yoon IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.11

<P>We previously reported that insulin-like growth factor-II mRNA-binding protein-3 (IMP-3) depletion (IMP-3(δ)) was shown to inhibit invadopodia formation and extracellular matrix degradation capacity in oral squamous cell carcinoma (OSCC) cells. In this study, we found that IMP-3(δ) cells significantly downregulated the podoplanin (PDPN) level, which resulted in a loss of extracellular matrix degradation activity, although invadopodia was still thriving. From RNA in situ hybridization using a digoxigenin-labeled 3'UTR recognition probe of PDPN and reporter assay with 3'UTR of the PDPN gene cloned downstream from the luciferase reporter gene, we revealed that IMP-3 depletion was shown to be downregulated, which most probably lowered PDPN gene expression by reducing mRNA stabilization. In a xenograft model, PDPN depletion was the cause of a decrease in tumor volume and regional infiltration into nearby stroma. Taken together, transforming growth factor beta 1 increased PDPN expression, which potentiated cancer invasion through increased invadopodia formation and extracellular matrix degradation in the low invasive OSCC cell line. Reciprocally, interleukin-1 beta secreted by OSCC cells, stimulated transforming growth factor beta 1 secretion from stromal fibroblasts to induce PDPN expression in OSCC cells. In addition, a retrospective investigation of OSCC patients found that IMP-3 and PDPN expression significantly correlated with lymph node metastasis of OSCC patients. Moreover, co-expression of IMP-3 and PDPN were frequently detected both in primary and lymph nodes metastatic OSCC cells using immunohistochemical dual staining. Thus, the IMP-3-PDPN axis may be a sensitive target molecule in anti-invadopodia therapy for the treatment of metastatic cancers.</P>

Transcriptional regulation of the interleukin-11 gene by oncogenic Ras.

Shin, Soon Young,Choi, Chan,Lee, Hong Ghi,Lim, Yoongho,Lee, Young Han IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.12

<P>Interleukin-11 (IL-11), which belongs to a class of IL6-type cytokines, plays an important role in inflammation, motility and invasion in cancer. The ras mutation is frequently found in human cancer, but little is known regarding the transcriptional activation of the IL-11 gene by the Ras signal pathway in tumour cells. In this study, we investigated the role of Ras in the regulation of IL-11 using two different cell model systems: mouse NIH3T3 cells over-expressing oncogenic Ras with a tet-on system and Capan-1 human pancreatic carcinoma cells harbouring a K-ras mutation. We found that IL-11 expression was up-regulated at the transcriptional level by oncogenic Ras. Activation of the AP-1 response element, located between -153 and -30 in the 5'-regulatory region of the IL-11 gene, was necessary for oncogenic Ras-induced IL-11 promoter activation. AP-1 proteins, including Fra-1 and Fra-2, were up-regulated through the Raf/MEK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways by oncogenic Ras. Knockdown of Fra-1 by siRNA in NIH3T3 or Capan-1 cells strongly attenuated oncogenic Ras-induced IL-11 expression. Additionally, inhibition of JNK, p38 and Stat3 abrogated oncogenic Ras-induced IL-11 expression. These results suggest that both the PI3K and Raf pathways are necessary for the expression of IL-11 in oncogenic Ras-mutated cells, and that JNK, p38 and Stat3 also contribute to oncogenic Ras-induced IL-11 expression.</P>

Guggulsterone induces heme oxygenase-1 expression through activation of Nrf2 in human mammary epithelial cells: PTEN as a putative target.

Almazari, Inas,Park, Jong-Min,Park, Sin-Aye,Suh, Jin-Young,Na, Hye-Kyung,Cha, Young-Nam,Surh, Young-Joon IRL Press] ; Oxford University Press 2012 Carcinogenesis Vol.33 No.2

<P>Guggulsterone (GS) [4,17(20)-pregnadiene-3,16-dione] is a phytosterol found in the gum resin of the Commiphora mukul. GS exists naturally in two stereoisomers: E-GS (cis-GS) and Z-GS (trans-GS). In this study, the effects of both isomers on expression of the cytoprotective enzyme heme oxygenase-1 (HO-1) were evaluated in human mammary epithelial (MCF10A) cells. NF-E2-related factor 2 (Nrf2) is considered a master regulator in activating antioxidant response element (ARE)-driven expression of HO-1 and many other antioxidant/cytoprotective proteins. cis-GS upregulated the transcription and protein expression of HO-1 to a greater extent than did trans-GS. cis-GS treatment enhanced nuclear translocation and ARE-binding activity of Nrf2. MCF10A cells transfected with an ARE luciferase construct exhibited significantly elevated Nrf2 transcriptional activity upon cis-GS treatment compared with cells transfected with the control vector. In addition, silencing of the Nrf2 gene abrogated cis-GS-induced expression of HO-1. Incubation of MCF10A cells with cis-GS increased phosphorylation of Akt. The pharmacological inhibition of phosphoinositide 3-kinase (PI3K), an upstream kinase responsible for Akt phosphorylation, abrogated cis-GS-induced Nrf2 nuclear translocation. Pretreatment with the thiol-reducing agents attenuated Akt phosphorylation, Nrf2 activation and HO-1 expression, suggesting that cis-GS may cause thiol modification of an upstream signaling modulator. Phosphatase and Tensin Homologue Deleted on Chromosome 10 (PTEN) is a negative regulator of the PI3K-Akt axis. The mutation in cysteine 124 present in the catalytic domain of PTEN abolished cis-GS-induced HO-1 expression as well as Akt phosphorylation. Whether this cysteine is a 'bona fide' target of cis-GS in its activation of Nrf2 needs additional investigation.</P>