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Chakraborty D, Benham V, Jdanov V, Bullard B, Leal AS, Liby KT, Bernard JJ. A BET Bromodomain Inhibitor Suppresses Adiposity-Associated Malignant Transformation. Cancer Prev Res (Phila) 2017; 11:129-142. [PMID: 29246955 DOI: 10.1158/1940-6207.capr-17-0262] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/24/2017] [Accepted: 12/07/2017] [Indexed: 11/16/2022]
Abstract
Almost half a million of all new cancers have been attributed to obesity and epidemiologic evidence implicates visceral adipose tissue (VAT) and high-fat diets (HFD) in increasing cancer risk. We demonstrated that VAT-derived fibroblast growth factor 2 (FGF2) from mice fed an HFD or obese individuals stimulates the malignant transformation of epithelial cells. Mechanism-based strategies to prevent this VAT-enhanced tumorigenesis have not been explored. Clinical studies have indicated that bromodomain inhibitors have considerable potential as therapeutic agents for cancer by inhibiting the activity of several oncogenes, including c-Myc; however, their chemopreventive activity is unknown. We show herein that mice with visceral adiposity have elevated nuclear c-Myc expression in their epidermis. We hypothesized that the bromodomain inhibitor I-BET-762 (I-BET) would have efficacy in the prevention of malignant transformation by VAT and FGF2. We tested this hypothesis using our novel models of VAT-stimulated transformation in vitro and FGF2- stimulated tumor formation in vivo We found that I-BET significantly attenuates VAT and FGF2-stimulated transformation and inhibits VAT-induced c-Myc protein expression in several skin and breast epithelial cell lines. Moreover, I-BET attenuated tumor growth significantly in FGF2-treated nude mice. Work is ongoing to determine the role of visceral adiposity in c-Myc activity in several tissues and determine the inhibitory effect of I-BET on VAT-promoted tumors in vivoCancer Prev Res; 11(3); 129-42. ©2017 AACRSee related editorial by Berger and Scacheri, p. 125.
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Affiliation(s)
- Debrup Chakraborty
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Vanessa Benham
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Vladislav Jdanov
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Blair Bullard
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Ana S Leal
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Karen T Liby
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Jamie J Bernard
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan.
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2
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Chakraborty D, Benham V, Bullard B, Kearney T, Hsia HC, Gibbon D, Demireva EY, Lunt SY, Bernard JJ. Fibroblast growth factor receptor is a mechanistic link between visceral adiposity and cancer. Oncogene 2017; 36:6668-6679. [PMID: 28783178 PMCID: PMC5709202 DOI: 10.1038/onc.2017.278] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/19/2017] [Accepted: 07/03/2017] [Indexed: 02/07/2023]
Abstract
Epidemiological evidence implicates excess adipose tissue in increasing cancer risk. Despite a steeply rising global prevalence of obesity, how adiposity contributes to transformation (stage a non-tumorigenic cell undergoes to become malignant) is unknown. To determine the factors in adipose tissue that stimulate transformation, we used a novel ex vivo system of visceral adipose tissue (VAT)-condition medium-stimulated epithelial cell growth in soft agar. To extend this system in vivo, we used a murine lipectomy model of ultraviolet light B-induced, VAT-promoted skin tumor formation. We found that VAT from mice and obese human donors stimulated growth in soft agar of non-tumorigenic epithelial cells. The difference in VAT activity was associated with fibroblast growth factor-2 (FGF2) levels. Moreover, human and mouse VAT failed to stimulate growth in soft of agar in cells deficient in FGFR-1 (FGF2 receptor). We also demonstrated that circulating levels of FGF2 were associated with non-melanoma tumor formation in vivo. These data implicate FGF2 as a major factor VAT releases to transform epithelial cells-a novel, potential pathway of VAT-enhanced tumorigenesis. Strategies designed to deplete VAT stores of FGF2 or inhibit FGFR-1 in abdominally obese individuals may be important cancer prevention strategies as well as adjuvant therapies for improving outcomes.
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Affiliation(s)
- D Chakraborty
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - V Benham
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - B Bullard
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - T Kearney
- Division of Surgical Oncology, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - H C Hsia
- Section of Plastic Surgery, Department of Surgery, Yale School of Medicine, New Haven, CT, USA
| | - D Gibbon
- Summit Medical4 Group, Livingston, NJ, USA
| | - E Y Demireva
- Office for the Vice President for Research and Graduate Studies, Michigan State University, East Lansing, MI, USA
| | - S Y Lunt
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - J J Bernard
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
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Dai M, Feng M, Ye Y, Wu X, Liu D, Liao M, Cao W. Exogenous avian leukosis virus-induced activation of the ERK/AP1 pathway is required for virus replication and correlates with virus-induced tumorigenesis. Sci Rep 2016; 6:19226. [PMID: 26754177 PMCID: PMC4709637 DOI: 10.1038/srep19226] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 12/03/2015] [Indexed: 12/13/2022] Open
Abstract
A proteomics approach was used to reveal the up-regulated proteins involved in the targeted mitogen-activated protein kinase (MAPK) signal transduction pathway in DF-1 cells after ALV subgroup J (ALV-J) infection. Next, we found that ALV-J CHN06 strain infection of DF-1 cells correlated with extracellular signal-regulated kinase 2 (ERK2) activation, which was mainly induced within 15 min, a very early stage of infection, and at a late infection stage, from 108 h to 132 h post-infection. Infection with other ALV subgroup (A/B) strains also triggered ERK/MAPK activation. Moreover, when activating ERK2, ALV subgroups A, B and J simultaneously induced the phosphorylation of c-Jun, an AP1 family member and p38 activation but had no obvious effect on JNK activation at either 15 min or 120 h. Interestingly, only PD98059 inhibited the ALV-induced c-Jun phosphorylation while SP600125 or SB203580 had no influence on c-Jun activation. Furthermore, the viral gp85 and gag proteins were found to contribute to ERK2/AP1 activation. Additionally, the specific ERK inhibitor, PD980509, significantly suppressed ALV replication, as evidenced by extremely low levels of ALV promoter activity and ALV-J protein expression. In vivo analysis of ERK2 activation in tumor cells derived from ALV-J-infected chicken demonstrated a strong correlation between ERK/MAPK activation and virus-associated tumorigenesis.
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Affiliation(s)
- Manman Dai
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
| | - Min Feng
- College of Animal Science, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
| | - Yu Ye
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
| | - Xiaochan Wu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
| | - Di Liu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
| | - Ming Liao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
- Key Laboratory of Veterinary Vaccine Innovation of the Ministry of Agriculture
- South China Collaborative innovation Center for Prevention and Control of poultry Infectious diseases and Safety of Poultry Products.
| | - Weisheng Cao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, People’s Republic of China
- Key Laboratory of Veterinary Vaccine Innovation of the Ministry of Agriculture
- South China Collaborative innovation Center for Prevention and Control of poultry Infectious diseases and Safety of Poultry Products.
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Arul N, Cho YY. A Rising Cancer Prevention Target of RSK2 in Human Skin Cancer. Front Oncol 2013; 3:201. [PMID: 23936765 PMCID: PMC3733026 DOI: 10.3389/fonc.2013.00201] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/23/2013] [Indexed: 02/06/2023] Open
Abstract
RSK2 is a p90 ribosomal S6 kinase family (p90(RSK)) member regulating cell proliferation and transformation induced by tumor promoters such as epithelial growth factor (EGF) and 12-O-tetradecanoylphorbol-13-acetate. This family of p90(RSK) has classified as a serine/threonine kinase that respond to many growth factors, peptide hormones, neurotransmitters, and environmental stresses such as ultraviolet (UV) light. Our recent study demonstrates that RSK2 plays a key role in human skin cancer development. Activation of RSK2 by EGF and UV through extracellular-activated protein kinases signaling pathway induces cell cycle progression, cell proliferation, and anchorage-independent cell transformation. Moreover, knockdown of RSK2 by si-RNA or sh-RNA abrogates cell proliferation and cell transformation of non-malignant human skin keratinocyte, and colony growth of malignant melanoma (MM) cells in soft agar. Importantly, activated and total RSK2 protein levels are highly detected in human skin cancer tissues including squamous cell carcinoma, basal-cell carcinoma, and MM. Kaempferol and eriodictyol are natural substances to inhibit kinase activity of the RSK2 N-terminal kinase domain, which is a critical kinase domain to transduce their activation signals to the substrates by phosphorylation. In this review, we discuss the role of RSK2 in skin cancer, particularly in activation of signaling pathways and potent natural substances to target RSK2 as chemopreventive and therapeutic agents.
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Affiliation(s)
- Narayanasamy Arul
- College of Pharmacy, The Catholic University of Korea, Bucheon-si, Republic of Korea
| | - Yong-Yeon Cho
- College of Pharmacy, The Catholic University of Korea, Bucheon-si, Republic of Korea
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Myers MV, Manning HC, Coffey RJ, Liebler DC. Protein expression signatures for inhibition of epidermal growth factor receptor-mediated signaling. Mol Cell Proteomics 2011; 11:M111.015222. [PMID: 22147731 PMCID: PMC3277773 DOI: 10.1074/mcp.m111.015222] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Analysis of cellular signaling networks typically involves targeted measurements of phosphorylated protein intermediates. However, phosphoproteomic analyses usually require affinity enrichment of phosphopeptides and can be complicated by artifactual changes in phosphorylation caused by uncontrolled preanalytical variables, particularly in the analysis of tissue specimens. We asked whether changes in protein expression, which are more stable and easily analyzed, could reflect network stimulation and inhibition. We employed this approach to analyze stimulation and inhibition of the epidermal growth factor receptor (EGFR) by EGF and selective EGFR inhibitors. Shotgun analysis of proteomes from proliferating A431 cells, EGF-stimulated cells, and cells co-treated with the EGFR inhibitors cetuximab or gefitinib identified groups of differentially expressed proteins. Comparisons of these protein groups identified 13 proteins whose EGF-induced expression changes were reversed by both EGFR inhibitors. Targeted multiple reaction monitoring analysis verified differential expression of 12 of these proteins, which comprise a candidate EGFR inhibition signature. We then tested these 12 proteins by multiple reaction monitoring analysis in three other models: 1) a comparison of DiFi (EGFR inhibitor-sensitive) and HCT116 (EGFR-insensitive) cell lines, 2) in formalin-fixed, paraffin-embedded mouse xenograft DiFi and HCT116 tumors, and 3) in tissue biopsies from a patient with the gastric hyperproliferative disorder Ménétrier's disease who was treated with cetuximab. Of the proteins in the candidate signature, a core group, including c-Jun, Jagged-1, and Claudin 4, were decreased by EGFR inhibitors in all three models. Although the goal of these studies was not to validate a clinically useful EGFR inhibition signature, the results confirm the hypothesis that clinically used EGFR inhibitors generate characteristic protein expression changes. This work further outlines a prototypical approach to derive and test protein expression signatures for drug action on signaling networks.
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Affiliation(s)
- Matthew V Myers
- Jim Ayers Institute for Precancer Detection and Diagnosis, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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Cho YY, Yao K, Kim HG, Kang BS, Zheng D, Bode AM, Dong Z. Ribosomal S6 kinase 2 is a key regulator in tumor promoter induced cell transformation. Cancer Res 2007; 67:8104-12. [PMID: 17804722 PMCID: PMC2822657 DOI: 10.1158/0008-5472.can-06-4668] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ribosomal S6 kinase 2 (RSK2), a member of the p90(RSK) (RSK) family of proteins, is a widely expressed serine/threonine kinase that is activated by extracellular signal-regulated kinase 1/2 and phosphoinositide-dependent kinase 1 in response to many growth factors and peptide hormones. Its activation signaling enhances cell survival. However, the roles of RSK2 in cell transformation have not yet been elucidated. Here, we found that RSK2 is a critical serine/threonine kinase for the regulation of cell transformation. When cells were stimulated with tumor promoters, such as epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA), phosphorylation of RSK was increased within 5 min. Cell proliferation was suppressed in RSK2(-/-) mouse embryonic fibroblasts (MEFs) compared with RSK2(+/+) MEFs. Moreover, RSK2(-/-) MEFs accumulated at the G(1) phase of the cell cycle under normal cell culture conditions as well as after stimulation with EGF or TPA. In the anchorage-independent cell transformation assay (soft agar), stable expression of RSK2 in JB6 cells significantly enhanced colony formation in either the presence or absence of tumor promoters. Furthermore, knockdown of RSK2 with small interfering RNA-RSK2 suppressed constitutively active Ras (Ras(G12V))-induced foci formation in NIH3T3 cells. In addition, kaempferol, an inhibitor of RSK2, suppressed EGF-induced colony formation of JB6 Cl41 cells in soft agar, which was associated with inhibition of histone H3 phosphorylation (Ser(10)). These results showed that RSK2 is a key regulator for cell transformation induced by tumor promoters such as EGF and TPA.
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Affiliation(s)
- Yong-Yeon Cho
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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Hansen ME, Pessah IN, Matsumura F. Heptachlor epoxide induces a non-capacitative type of Ca2+ entry and immediate early gene expression in mouse hepatoma cells. Toxicology 2006; 220:218-31. [PMID: 16469423 DOI: 10.1016/j.tox.2006.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 01/02/2006] [Accepted: 01/05/2006] [Indexed: 10/25/2022]
Abstract
The effects of the organochlorine (OC) liver tumor promoter heptachlor epoxide (HE) and a related non-tumor promoting OC, delta-hexachlorocyclohexane (delta-HCH), on the dynamics of intracellular calcium (Ca2+) were investigated in mouse 1c1c7 hepatoma cells. HE induced a non-capacitative, Ca2+ entry-like phenomenon, which was transient and concentration-dependent with 10 and 50 microM HE. The plasma membrane Ca2+ channel blocker SKF-96365 antagonized this HE-induced Ca2+ entry. delta-HCH failed to induce Ca2+ entry, rather it antagonized the HE-induced Ca2+ entry. Both HE and delta-HCH induced Ca2+ release from endoplasmic reticulum (ER) at treatment concentrations as low as 10 microM; at 50 microM, the former induced 5x as much Ca2+ release as the latter. The HE-induced Ca2+ release from the ER was antagonized using the IP3 receptor/channel blocker xestospongin C, suggesting that HE induces ER Ca2+ release through the IP3 receptor/channel pore. These results show that the effect of HE on cellular Ca2+ mimics that of mitogens such as epidermal and hepatocyte growth factors. They also provide insight into the similarities and differences between tumorigenic and non-tumorigenic OCs, in terms of the mechanisms and the extent of the [Ca2+]i increased by these agents.
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Affiliation(s)
- Mark E Hansen
- Department of Environmental Toxicology, University of California, Davis, CA 95616, USA
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8
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Choi HS, Choi BY, Cho YY, Mizuno H, Kang BS, Bode AM, Dong Z. Phosphorylation of histone H3 at serine 10 is indispensable for neoplastic cell transformation. Cancer Res 2005; 65:5818-27. [PMID: 15994958 PMCID: PMC2227263 DOI: 10.1158/0008-5472.can-05-0197] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Very little is known about the role of histone H3 phosphorylation in malignant transformation and cancer development. Here, we examine the function of H3 phosphorylation in cell transformation in vivo. Introduction of small interfering RNA-H3 into JB6 cells resulted in decreased epidermal growth factor (EGF)-induced cell transformation. In contrast, wild-type histone H3 (H3 WT)-overexpressing cells markedly stimulated EGF-induced cell transformation, whereas the H3 mutant S10A cells suppressed transformation. When H3 WT was overexpressed, EGF induction of c-fos and c-jun promoter activity was significantly increased compared with control cells but not in the H3 mutant S10A or S28A cells. In addition, activator protein-1 activity in H3 WT-overexpressing cells was markedly up-regulated by EGF in contrast to the H3 mutant S10A or S28A cells. These results indicate that the phosphorylation of histone H3 at Ser10 is an essential regulatory mechanism for EGF-induced neoplastic cell transformation.
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Affiliation(s)
- Hong Seok Choi
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Bu Young Choi
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Yong-Yeon Cho
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Hideya Mizuno
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Bong Seok Kang
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Ann M. Bode
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
| | - Zigang Dong
- Hormel Institute, University of Minnesota1, Austin, Minnesota 55912, USA
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Cho YY, Bode AM, Mizuno H, Choi BY, Choi HS, Dong Z. A novel role for mixed-lineage kinase-like mitogen-activated protein triple kinase alpha in neoplastic cell transformation and tumor development. Cancer Res 2004; 64:3855-64. [PMID: 15172994 DOI: 10.1158/0008-5472.can-04-0201] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Previously, no member of the mixed-lineage kinase (MLK) protein family was known to function as an oncogene. Here, we demonstrate that MLK-like mitogen-activated protein triple kinase (MLTK)-alpha, a member of the MLK family, induced neoplastic cell transformation and tumorigenesis in athymic nude mice. Introduction of small interference RNA (siRNA)-MLTK-alpha into MLTK-alpha-overexpressing cells dramatically suppressed cell transformation. Nuclear accumulation of the pHisG-MLTK-alpha fusion protein was observed after epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate treatment. Phosphorylation of downstream mitogen-activated protein kinase-targeted transcription factors including c-Myc, Elk-1, c-Jun, and activating transcription factor (ATF) 2 was also differentially enhanced in MLTK-alpha-overexpressing cells exposed to epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate stimulation compared with cells expressing mock vector or siRNA-MLTK-alpha. Very importantly, MLTK-alpha-overexpressing cells formed fibrosarcomas when injected s.c. into athymic nude mice, whereas almost no tumor formation was observed in mice that received injections of mock or siRNA-MLTK-alpha stably transfected cells. These results are the first to indicate that MLTK-alpha plays a key role in neoplastic cell transformation and cancer development.
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Affiliation(s)
- Yong-Yeon Cho
- Hormel Institute University of Minnesota, Austin, Minnesota 55912, USA
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Samuel S, Bernstein LR. Adhesion, migration, transcriptional, interferon-inducible, and other signaling molecules newly implicated in cancer susceptibility and resistance of JB6 cells by cDNA microarray analyses. Mol Carcinog 2003; 39:34-60. [PMID: 14694446 DOI: 10.1002/mc.10163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Relative expression levels of 9500 genes were determined by cDNA microarray analyses in mouse skin JB6 cells susceptible (P+) and resistant (P-) to 12-O-tetradecanoyl phorbol-13 acetate (TPA)-induced neoplastic transformation. Seventy-four genes in 6 functional classes were differentially expressed: (I) extracellular matrix (ECM) and basement membrane (BM) proteins (20 genes). P+ cells express higher levels than P- cells of several collagens and proteases, and lower levels of protease inhibitors. Multiple genes encoding adhesion molecules are expressed preferentially in P- cells, including six genes implicated in axon guidance and adhesion. (II) Cytoskeletal proteins (13 genes). These include actin isoforms and regulatory proteins, almost all preferentially expressed in P- cells. (III) Signal transduction proteins (12 genes). Among these are Ras-GTPase activating protein (Ras-GAP), the deleted in oral cancer-1 and SLIT2 tumor suppressors, and connexin 43 (Cx43) gap junctional protein, all expressed preferentially in P- cells. (IV) Interferon-inducible proteins (3 genes). These include interferon-inducible protein (IFI)-16, an Sp1 transcriptional regulator expressed preferentially in P- cells. (V) Other transcription factors (4 genes). Paired related homeobox gene 2 (Prx2)/S8 homeobox, and retinoic acid (RA)-regulated nur77 and cellular retinoic acid-binding protein II (CRABPII) transcription factors are expressed preferentially in P- cells. The RIN-ZF Sp-transcriptional suppressor exhibits preferential P+ expression. (VI) Genes of unknown functions (22 sequences). Numerous mesenchymal markers are expressed in both cell types. Data for multiple genes were confirmed by real-time PCR. Overall, 26 genes were newly implicated in cancer. Detailed analyses of the functions of the genes and their interrelationships provided converging evidence for their possible roles in implementing genetic programs mediating cancer susceptibility and resistance. These results, in conjunction with cell wounding and phalloidin staining data, indicated that concerted genetic programs were implemented that were conducive to cell adhesion and tumor suppression in P- cells and that favored matrix turnover, cell motility, and abrogation of tumor suppression in P+ cells. Such genetic programs may in part be orchestrated by Sp-, RA-, and Hox-transcriptional regulatory pathways implicated in this study.
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Affiliation(s)
- Shaija Samuel
- Department of Pathology and Laboratory Medicine, Texas A & M University System Health Science Center, College Station, Texas, USA
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11
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Arnott CH, Scott KA, Moore RJ, Hewer A, Phillips DH, Parker P, Balkwill FR, Owens DM. Tumour necrosis factor-alpha mediates tumour promotion via a PKC alpha- and AP-1-dependent pathway. Oncogene 2002; 21:4728-38. [PMID: 12101411 DOI: 10.1038/sj.onc.1205588] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2001] [Revised: 04/08/2002] [Accepted: 04/15/2002] [Indexed: 01/21/2023]
Abstract
Tumour necrosis factor-alpha (TNF-alpha) deficient mice (TNF-alpha(-/-) mice) are resistant to skin carcinogenesis. Cellular signalling via the transcription factor complex AP-1 is thought to play a key role in tumour promotion. The induction of a specific subset of AP-1 responsive genes thought to be important for tumour development, namely GM-CSF, MMP-9 and MMP-3, was suppressed in TNF-alpha(-/-) compared to wild-type mouse skin in response to the tumour promotor TPA. The differential induction of these genes correlated with a temporal shift in AP-1 activation and c-Jun expression in TNF-alpha(-/-) compared to wild-type epidermis. The major receptor for TPA-induced signalling in basal keratinocytes, PKC alpha, was also differentially regulated in wild-type compared with TNF-alpha(-/-) epidermis. A marked delay in TPA-induced intracellular translocation and downregulation of PKC alpha was observed in TNF-alpha(-/-) epidermis, which correlated with the deregulated TPA-induced AP-1 activation and c-Jun expression. The frequency of DNA adduct formation and c-Ha-ras mutations was the same in wild-type and TNF-alpha(-/-) epidermis after DMBA treatment, suggesting that TNF-alpha was not involved in tumour initiation. These data suggest that the pro-inflammatory cytokine TNF-alpha is a critical mediator of tumour promotion, acting via a PKC alpha- and AP-1-dependent pathway. This may be one mechanism by which chronic inflammation increases susceptibility to cancer.
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Affiliation(s)
- Caroline H Arnott
- Cancer Research UK Translational Oncology Laboratory, Bart's and The London School of Medicine and Dentistry, Queen Mary, University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, UK
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12
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Young MR, Nair R, Bucheimer N, Tulsian P, Brown N, Chapp C, Hsu TC, Colburn NH. Transactivation of Fra-1 and consequent activation of AP-1 occur extracellular signal-regulated kinase dependently. Mol Cell Biol 2002; 22:587-98. [PMID: 11756554 PMCID: PMC139745 DOI: 10.1128/mcb.22.2.587-598.2002] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mitogen-activated protein (MAP) kinase, extracellular-signal-regulated kinases (ERKs) play an important role in activating AP-1-dependent transcription. Studies using the JB6 mouse epidermal model and a transgenic mouse model have established a requirement for AP-1-dependent transcription in tumor promotion. Tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) and epidermal growth factor induce activator protein 1 (AP-1) activity and neoplastic transformation in JB6 transformation-sensitive (P(+)) cells, but not in transformation-resistant (P(-)) variants. The resistance in one of the P(-) variants can be attributed to the low levels of the MAP kinases, ERKs 1 and 2, and consequent nonresponsiveness to AP-1 activation. The resistant variant is not deficient in c-fos transcription. The purpose of these studies was to define the targets of activated ERK that lead to AP-1 transactivation. The results establish that the transactivation domain of Fra-1 can be activated, that activation of Fra-1 is ERK dependent, and that a putative ERK phosphorylation site must be intact for activation to occur. Fra-1 was activated by TPA in ERK-sufficient P(+) cells but not in ERK-deficient P(-) cells. A similar activation pattern was seen for c-Fos but not for Fra-2. Gel shift analysis identified Fra-1 as distinguishing mitogen-activated (P(+)) from nonactivated (P(-)) AP-1 complexes. A second AP-1-nonresponsive P(-) variant that underexpresses Fra-1 gained AP-1 response upon introduction of a Fra-1 expression construct. These observations suggest that ERK-dependent activation of Fra-1 is required for AP-1 transactivation in JB6 cells.
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Affiliation(s)
- Matthew R Young
- Basic Research Laboratory, National Cancer Institute-Frederick. Intramural Research Support Program, Science Applications International Corporation-Frederick, Frederick, Maryland 21702, USA.
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13
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Hansen ME, Matsumura F. Effects of heptachlor epoxide on components of various signal transduction pathways important in tumor promotion in mouse hepatoma cells. Determination of the most sensitive tumor promoter related effect induced by heptachlor epoxide. Toxicology 2001; 160:139-53. [PMID: 11246134 DOI: 10.1016/s0300-483x(00)00445-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of the organochlorine (OC) liver tumor promoter heptachlor epoxide (HE; 0, 0.1, 1, 10, and 50 microM) on several cellular tumor promoter-sensitive parameters were studied in mouse 1c1c7 hepatoma cells in an effort to identify the most sensitive biomarker for OC promoter exposure and the critical pathway and target of OC promoters. The levels of Ca2+ in the endoplasmic reticulum (ER) store, connexin43 (Cx43), PLCgamma(1), nPKCvarepsilon, and AP-1 DNA binding in nucleus were studied to screen for effects induced by submicromolar HE levels. While all the parameters tested elicited effects, particulate PLCgamma(1) and AP-1 DNA binding were found to be the most sensitive parameters affected by HE on both dose and temporal bases. Their levels were increased with 10- to 100-fold lower HE concentrations than were required to affect nPKCvarepsilon or Cx43. Further, with the lower HE dosages, particulate PLCgamma(1) and nuclear AP-1 were positively modulated by HE after 1 h versus 3 or 72 h for nPKCvarepsilon and Cx43. Ca2+ store depletion was probably the third most sensitive parameter, after AP-1 and PLCgamma(1). These results suggest the tyrosine kinase growth factor receptor pathway is the probable critical pathway for HE-induce tumor promotion with the critical target most likely being upstream of PLCgamma(1) and AP-1. This work also demonstates that upon exposure to a tumor promoter such as HE, many hepatocellular effects or changes result, suggesting that a cellular-program shift occurs similar to that described by the resistant hepatocyte model after exposure to a carcinogen or enzyme inducer.
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Affiliation(s)
- M E Hansen
- Institute of Toxicology and Environmental Health, University of California, Davis, CA 95616, USA
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14
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Zhong SP, Ma WY, Quealy JA, Zhang Y, Dong Z. Organ-specific distribution of AP-1 in AP-1 luciferase transgenic mice during the maturation process. Am J Physiol Regul Integr Comp Physiol 2001; 280:R376-81. [PMID: 11208564 DOI: 10.1152/ajpregu.2001.280.2.r376] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Activator protein-1 (AP-1), a dimeric complex consisting of proteins encoded by the jun and fos gene families, is a transcription factor induced by a variety of signals including those eliciting proliferation, differentiation, and neoplastic transformation. Although AP-1 has been widely studied in the last decade, physiological levels of AP-1 in different tissues are unclear. In the present study, we analyzed AP-1 activity in several organs (liver, kidney, brain, lung, spleen, heart, skin) of AP-1-luciferase transgenic mice of various ages. Results of these studies indicate that the level of AP-1 in young mice is much higher than that in older mice, and, second, that the skin contains considerably higher levels of AP-1 than other organs. The level of phosphorylated extracellular signal-regulated protein kinase (ERK) in skin was higher in 1- and 2-day-old mice than in mice of other ages. In addition, phosphorylated p38 kinase was high in 2-day-old and 1-wk-old mice, but phosphorylated c-Jun NH(2)-terminal kinase was not detected at any age. AP-1 activity and level of phosphorylated ERKs declined with maturation. These results imply that AP-1 activity mediated through an ERKs-dependent pathway may be involved in skin development.
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Affiliation(s)
- S P Zhong
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
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15
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Hsu TC, Young MR, Cmarik J, Colburn NH. Activator protein 1 (AP-1)- and nuclear factor kappaB (NF-kappaB)-dependent transcriptional events in carcinogenesis. Free Radic Biol Med 2000; 28:1338-48. [PMID: 10924853 DOI: 10.1016/s0891-5849(00)00220-3] [Citation(s) in RCA: 200] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Generation of reactive oxygen species (ROS) during metabolic conversion of molecular oxygen imposes a constant threat to aerobic organisms. Other than the cytotoxic effects, many ROS and oxidants are also potent tumor promoters linking oxidative stress to carcinogenesis. Clonal variants of mouse epidermal JB6 cells originally identified for their differential susceptibility to tumor promoters also show differential reduction-oxidation (redox) responses providing a unique model to study oxidative events in tumor promotion. AP-1 and NF-kappaB, inducible by tumor promoters or oxidative stimuli, show differential protein levels or activation in response to tumor promoters in JB6 cells. We further demonstrated that AP-1 and NF-kappaB are both required for maintaining the transformed phenotypes where inhibition of either activity suppresses transformation response in JB6 cells as well as human keratinocytes and transgenic mouse. NF-kappaB proteins or extracellular signal-regulated kinase (ERK) but not AP-1 proteins are shown to be sufficient for conversion from transformation-resistant to transformation-susceptible phenotype. Insofar as oxidative events regulate AP-1 and NF-kappaB transactivation, these oxidative events can be important molecular targets for cancer prevention.
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Affiliation(s)
- T C Hsu
- IRSP, SAIC-Frederick, Frederick, MD, USA
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16
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Nomura M, Ma WY, Huang C, Yang CS, Bowden GT, Miyamoto KI, Dong Z. Inhibition of Ultraviolet B-Induced AP-1 Activation by Theaflavins From Black Tea. Mol Carcinog 2000. [DOI: 10.1002/1098-2744(200007)28:3<148::aid-mc3>3.0.co;2-q] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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17
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Bernstein LR, Walker SE. Tumor promotion resistant cells are deficient in AP-1 DNA binding, JunD DNA binding and JunD expression and form different AP-1-DNA complexes than promotion sensitive cells. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1489:263-80. [PMID: 10673028 DOI: 10.1016/s0167-4781(99)00191-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The JB6 cell culture model is used to identify molecular determinants of susceptibility to the promotion of neoplastic transformation. Clonal variants susceptible to transformation ('P+' cells) form numerous anchorage-independent colonies in soft agar upon treatment with the phorbol ester tumor promoter TPA, whereas resistant variants ('P-' cells) do not. We now report that there is significantly less binding of activator protein-1 (AP-1) to its DNA binding site in P- cells than in P+ cells. Gel supershift assays were performed to detect association of all seven AP-1 family members with their DNA binding site in TPA-treated and -untreated P+ and P- cells. Significantly lower DNA binding and protein expression of JunD were detected in P- cells than in P+ cells. c-Jun was detected in P+, but not P-, AP-1-DNA complexes, and c-Fos was detected in P-, but not P+, AP-1-DNA complexes. These and other phenotype-specific differences in abundance and composition of AP-1-DNA complexes may play a role in the resistance of P- cells to tumor promoter-induced transformation.
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Affiliation(s)
- L R Bernstein
- Texas A&M Health Science Center, Department of Pathology and Laboratory Medicine, College Station, 77843-1114, USA.
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18
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Huang C, Ma WY, Dong Z. The extracellular-signal-regulated protein kinases (Erks) are required for UV-induced AP-1 activation in JB6 cells. Oncogene 1999; 18:2828-35. [PMID: 10362253 DOI: 10.1038/sj.onc.1202639] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mitogen activated protein (MAP) kinase belongs to a large family of serine/threonine protein kinases, including extracellular-signal-regulated protein kinases (Erks), P38 kinase and c-Jun N-terminal kinases (JNKs). Although previous work has shown that both Erks and JNKs are activated in cells in response to ultraviolet (UV) irradiation, most studies have focused only on the role of JNKs in UV-induced AP-1 activation. Hence, the role of Erks in UV-induced AP-1 activity is not well defined. We here have investigated this issue by using MAP kinase kinase (MEK1) inhibitor PD098059 and a dominant negative Erk2, as well as wild-type Erk2, in a JB6 cell model. PD098059 inhibited UVB- or UVC-induced AP-1 activity and phosphorylation of MEK1 and Erks, but not JNKs, in JB6 Cl 41 cells. Overexpression of wild-type Erk2 in Cl 30.7b cells that contain small amounts of Erks caused a 46.6- or 138.1-fold increase of AP-1 activity by UVB and UVC, respectively; introduction of a dominant negative Erk2 into Cl 41 cells significantly blocked the UV-induced Erks activation as well as the AP-1 activation. In contrast, overexpression of wild-type Erk2 in Cl 30.7b cells and dominant negative Erk2 in Cl 41 cells did not show a marked influence on the phosphorylation of JNKs. These results demonstrate that activation of Erks, in addition to the previously reported JNKs, is required for UV-induced AP-1 activation.
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Affiliation(s)
- C Huang
- The Hormel Institute, University of Minnesota, Austin 55912, USA
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19
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Huang C, Ma WY, Young MR, Colburn N, Dong Z. Shortage of mitogen-activated protein kinase is responsible for resistance to AP-1 transactivation and transformation in mouse JB6 cells. Proc Natl Acad Sci U S A 1998; 95:156-61. [PMID: 9419345 PMCID: PMC18158 DOI: 10.1073/pnas.95.1.156] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The JB6 mouse epidermal cell system, which includes tumor promotion-sensitive (P+) and tumor promotion-resistant (P-) cells, is a well-established and extensively used cell culture model for studying the mechanism of late-stage tumor promotion. Tumor promoters, such as 12-O-tetradecanoylphorbol 13-acetate (TPA) or epidermal growth factor (EGF), induce high levels of activator protein 1 (AP-1) activity and large, tumorigenic, anchorage-independent colonies in soft agar at a high frequency in JB6 P+ cells, but not in JB6 P- cells. We report here a molecular explanation for the defect in the AP-1 activation and promotion-resistant phenotype of P- cells. We demonstrate that the lack of AP-1 activation and cell transformation responses to TPA and EGF in P- cells appears attributable to the low level of mitogen-activated protein kinase (MAPK) (extracellular signal-regulated protein kinase, Erk) in these cells. TPA and EGF induce transactivation of AP-1 activity in P+ cells but not in P- cells. Nonphosphorylated forms and TPA- or EGF-induced phosphorylated forms of Erks (Erk1 and Erk2) in P- cells were much lower than those in P+ cells. Stable transfection of wild-type MAPK (Erk2) into P- cells restored its response to TPA and EGF for both AP-1 activation and cell transformation. These results suggest that the shortage of MAPK (Erk1 and Erk2) appears to be an important contributor to the tumor promotion-resistant phenotype in JB6 cells.
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Affiliation(s)
- C Huang
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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20
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Amstad PA, Liu H, Ichimiya M, Chang S, Berezesky IK, Trump BF. bcl-2 enhancement of malignant transformation in mouse epidermal JB6 cells. Mol Carcinog 1997; 20:231-9. [PMID: 9364213 DOI: 10.1002/(sici)1098-2744(199710)20:2<231::aid-mc10>3.0.co;2-b] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Increased bcl-2 expression is a common feature of many types of human malignancies, which implies that bcl-2 plays an important role in tumorigenesis. To better understand the molecular mechanisms of bcl-2-induced oncogenesis, we examined the effects of bcl-2 expression on transformation of mouse epidermal JB6 cells induced by the tumor promoter 12-O-tetradecanoylphorbol-13 acetate (TPA). Promotion-sensitive JB6 clone41 cells were transfected with the bcl-2-containing expression vector pD5-neo/bcl-2, and the soft agar growth of bcl-2-transfected cells and control cells were compared. bcl-2 overexpression in JB6 clone41 cells caused a TPA-induced soft-agar growth fivefold greater than the growth of nontransfected or vector-transfected (neo control) cells. bcl-2 expression in the absence of TPA did not lead to colony formation in soft agar. Because the level of the transcription factor activator protein 1 (AP-1) has been shown to be critical for the responsiveness of JB6 cells to TPA-induced transformation, we compared c-jun and c-fos expression as well as the AP-1-binding activity and the AP-1-mediated transactivation of the reporter construct TRE-CAT between bcl-2-expressing cells and control cells. When compared with control cells, bcl-2-transfected cells expressed significantly more c-fos but not c-jun after TPA treatment. Furthermore, the levels of AP-1 and AP-1-induced transactivation of TRE-CAT were greater in bcl-2-transfected cells than in control cells after TPA treatment. These results showed that bcl-2 cooperates with a tumor promoter such as TPA in the induction of malignant transformation in mouse epidermal cells and that bcl-2 enhances soft-agar growth by stimulating signaling pathways that led to increased AP-1 expression.
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Affiliation(s)
- P A Amstad
- Department of Pathology, University of Maryland, Baltimore 21201, USA
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21
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Kiss Z, Guyer B, Dong Z. Promotion-resistant JB6 mouse epidermal cells exhibit defects in phosphatidylethanolamine synthesis and phorbol ester-induced phosphatidylcholine hydrolysis. Biochem J 1997; 323 ( Pt 2):489-95. [PMID: 9163343 PMCID: PMC1218346 DOI: 10.1042/bj3230489] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The tumour-promotion-sensitive (P+) and -resistant (P-) variants of mouse JB6 epidermis-derived cells have often been used to study the requirements for the tumour-promoting effect of PMA. As part of an effort to identify the defect(s) in JB6 P- cells that might prevent the promoting effect of PMA, stimulation of phospholipase D (PLD)-mediated hydrolysis of phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) by PMA as well as the rate of phospholipid synthesis were compared in three P+ variants, two P- variants and a transformed variant of the JB6 cell line. PMA (5-100 nM) had significantly less stimulatory effect on PtdCho hydrolysis in P- cells than in P+ or transformed JB6 cells. The effects of PMA on PtdEtn hydrolysis in the P+ and P- cell lines were similar, whereas in transformed cells PMA had slightly less effect. Each JB6 cell line was found to contain similar amounts of PtdCho. In contrast, P- cells contained significantly less PtdEtn and a correspondingly higher level of ethanolamine phosphate compared with P+ and transformed cells. P- cells also secreted ethanolamine phosphate into the medium; this process was greatly enhanced by PMA. In the two P- variants the synthesis of PtdEtn from [14C]ethanolamine was reduced to various extents, whereas the rate of PtdCho synthesis was comparable in each JB6 cell line. The synthesis of PtdCho, but not PtdEtn, was greatly stimulated by PMA in both the P+ and P- clones. The results indicate that decreased synthesis/level of PtdEtn and suboptimal functioning of a PtdCho-specific PLD are common characteristics of the P- JB6 cells examined so far. The observed alterations in phospholipid metabolism may play a role in the resistance of P- cells to the tumour-promoting action of PMA.
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Affiliation(s)
- Z Kiss
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
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22
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Watts RG, Ben-Ari ET, Bernstein LR, Birrer MJ, Winterstein D, Wendel E, Colburn NH. c-jun and multistage carcinogenesis: association of overexpression of introduced c-jun with progression toward a neoplastic endpoint in mouse JB6 cells sensitive to tumor promoter-induced transformation. Mol Carcinog 1995; 13:27-36. [PMID: 7766308 DOI: 10.1002/mc.2940130106] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) and epidermal growth factor (EGF) induce neoplastic transformation, elevated c-jun protein expression, and activator protein-1 (AP-1)-dependent gene expression in JB6 mouse epidermal cells sensitive to tumor promoters (clone 415a P+ cells). In contrast, JB6 cells resistant to tumor promoter-induced transformation (clone 307b P- cells) exhibit a greatly reduced TPA or EGF inducible c-jun expression and AP-1 activity. We have recently shown that induced AP-1 is necessary for tumor promoter-induced transformation of P+ cells because introduction of a dominant negative c-jun mutant into P+ cells inhibits both AP-1 dependent transactivation and the transformation response to tumor promoter. The intent of the investigation presented here was to test the hypothesis that elevation of AP-1 activity is sufficient to cause progression to the P+ phenotype in P- cells or to the transformed phenotype in P+ cells. Clonally derived P+ and P- recipient cells transfected with a human c-jun expression construct and overexpressing c-jun protein were tested for progression by assaying for constitutive or inducible anchorage independent phenotype and nude-mouse tumorigenicity. Overexpression of c-jun did not produce progression in P- cells but did increase the probability of progression in P+ cells (two of five transfectant cell lines progressed to the tumor phenotype). In addition, c-jun overexpression did not increase AP-1 activity in any of the P-/c-jun transfectants or in the two of five P+/c-jun transfectants that acquired the transformed phenotype. The P+/c-jun transfectants that showed elevated AP-1 activity did not progress to the tumor phenotype, demonstrating that an increase in AP-1 activity is insufficient for this progression. Since P(+)-to-tumor phenotype progression occurred in cells overexpressing c-jun but not AP-1, we propose that P(+)-to-transformed phenotype progression is c-jun dependent and AP-1 independent.
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Affiliation(s)
- R G Watts
- Laboratory of Viral Carcinogenesis, NCI, FCRDC, Frederick, MD 21702, USA
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23
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Cmarik JL, Herschman H, Colburn NH. Preferential primary-response gene expression in promotion-resistant versus promotion-sensitive JB6 cells. Mol Carcinog 1994; 11:115-24. [PMID: 7916993 DOI: 10.1002/mc.2940110209] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The 12-O-tetradecanoylphorbol-13-acetate (TPA)-inducible sequence (TIS) genes are a set of primary response genes induced in Swiss 3T3 cells by TPA. They include three transcription factors, a prostaglandin synthase, and three proteins of unknown function. To ascertain which, if any TIS genes might be involved in tumor promotion, we examined the expression of these genes in response to tumor promoters in transformation promotion-sensitive (P+) and -resistant (P-) JB6 murine epidermal cells, a model used to identify events relevant to promotion. A subset of TIS genes (TIS1, TIS10, and TIS21) was preferentially induced by TPA in P-cells. In addition, TIS1 and TIS21 mRNAs were preferentially induced in P-cells by epidermal growth factor, another transformation promoter that distinguishes P+ from P-cells. TIS1 and TIS21 protein levels were also greater in TPA-treated P-cells than P+ cells. Forskolin, a cAMP-elevating anti-promoter, increased TPA-induced levels of TIS1, TIS10, and TIS21 mRNAs in P+ cells, ruling in potential roles for these genes in modulating tumor promotion. The anti-promoters fluocinolone acetonide, retinoic acid, and superoxide dismutase did not enhance TPA-induced levels of TIS1 and TIS21 mRNAs in P+ cells, suggesting that these inhibitors may act on other promotion-relevant genes. TIS1 encodes a member of the steroid receptor superfamily. TIS1 encodes a protein of unknown function with strong sequence similarity to BTG1, a proposed "anti-proliferative gene" (Rouault JP, Rimokh R, Tessa C, et al., EMBO J 11:1663-1670, 1992). Preferential induction by multiple promoters of these TIS genes in P-cells and enhancement of their induction in P+ cells by the anti-promoter forskolin make TIS1 and TIS21 candidates for promotion suppressor genes.
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Affiliation(s)
- J L Cmarik
- Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702
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24
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Dong Z, Birrer MJ, Watts RG, Matrisian LM, Colburn NH. Blocking of tumor promoter-induced AP-1 activity inhibits induced transformation in JB6 mouse epidermal cells. Proc Natl Acad Sci U S A 1994; 91:609-13. [PMID: 8290571 PMCID: PMC42998 DOI: 10.1073/pnas.91.2.609] [Citation(s) in RCA: 285] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
AP-1 transcriptional activity is stimulated by the transformation promoters phorbol 12-myristate 13-acetate ("12-O-tetradecanoylphorbol 13-acetate," TPA) and epidermal growth factor (EGF) in promotion-sensitive (P+) but not in promotion-resistant (P-) JB6 mouse epidermal cell lines. Although TPA stimulates expression of the jun and fos family genes, only c-jun expression shows higher elevation in P+ cells than in P- cells. The present study tests the hypothesis that induced AP-1 activity is required for tumor promoter-induced transformation in JB6 P+ cells. Both retinoic acid and the glucocorticoid fluocinolone acetonide inhibited basal and TPA-induced AP-1 activities that were tested with a stromelysin promoter-chloramphenicol acetyltransferase reporter gene in P+ cells. Since both retinoic acid and fluocinolone acetonide are active in inhibiting TPA-induced anchorage-independent transformation of P+ cells in the dose range that blocks TPA-induced AP-1 activity, their antipromoting effects may occur through inhibition of AP-1 activity. To test the hypothesis with a more specific inhibitor, stable clonal transfectants of P+ cells expressing dominant negative c-jun mutant encoding a transcriptionally inactive product were analyzed. All transfectants showed a block in TPA and EGF induction of AP-1 activity. All transfectants also showed inhibition of TPA-induced transformation, and most transfectants showed a block in EGF-induced transformation. These results indicate that AP-1 activity is required for TPA- or EGF-induced transformation. This work demonstrates that a specific block in induced AP-1 activity inhibits tumor promoter-induced transformation.
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Affiliation(s)
- Z Dong
- Biological Carcinogenesis and Development Program, PRI/DynCorp, Frederick, MD
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25
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Abstract
EGFR is a member of the tyrosine kinase family of cell surface receptors with a wide range of expression throughout development and in a variety of different cell types. The receptor can transmit signals to cells: i) upon interaction with ligands such as EGF, TGF alpha, amphiregulin or heparin binding EGF, ii) upon truncation or mutation of extracellular and/or intracellular domains, iii) upon amplification of a basal receptor activity (in the absence of ligand) through cooperation with other cellular signaling pathways or nuclear events (e.g. expression of v-erbA). The activated EGFR can exert pleiotropic functions on cells, depending on their tissue origin and state of differentiation. Under certain conditions it can also contribute to neoplasia and development of metastases. Such conditions can exist upon aberrant receptor/ligand expression and activation (e.g. in the wrong cell; at the wrong time; in the wrong amounts). Aberrant signalling can also occur through constitutive EGFR activation. Oncogenic potential of EGFR has been demonstrated in a wide range of experimental animals. EGFR is also implicated in human cancer, where it may contribute both to the initiation (glioblastoma) and progression (epithelial tumors) of the disease. EGFR may influence key steps in the processes of tumor invasion and dissemination. Involvement of EGFR in tumor spread may indicate a potential use of this receptor as a target for antimetastatic therapy.
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Affiliation(s)
- K Khazaie
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
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26
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Roseng LE, Rivedal E. Effect of glucocorticoids on TPA-induced inhibition of gap-junctional communication and morphological transformation in Syrian hamster embryo cells. Cancer Lett 1993; 72:25-30. [PMID: 8402570 DOI: 10.1016/0304-3835(93)90006-u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of glucocorticoids on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inhibition of gap-junctional intercellular communication (GJIC) and morphological transformation in Syrian hamster embryo (SHE) cells was examined. Fluocinolone acetonide (FA) and dexamethasone (DEX) almost completely suppressed the effect of TPA on induction of transformed morphology. On the other hand, up to 1000 times higher FA and DEX concentrations did not influence the inhibitory effect of TPA on GJIC. Neither treatment with these glucocorticoids for 4, 24 or 48 h before TPA exposure nor 24 h co-exposure with TPA altered the effect of TPA on GJIC. Thus the potent effect of glucocorticoids as inhibitors of the promotional effect of TPA on morphological transformation in SHE cells does not result in alterations of TPA-induced inhibition of GJIC.
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Affiliation(s)
- L E Roseng
- Laboratory for Environmental and Occupational Cancer, Norwegian Radium Hospital, Oslo
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27
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Sun Y, Nakamura K, Hegamyer G, Dong Z, Colburn N. No point mutation of Ha-ras or p53 genes expressed in preneoplastic-to-neoplastic progression as modeled in mouse JB6 cell variants. Mol Carcinog 1993; 8:49-57. [PMID: 8352891 DOI: 10.1002/mc.2940080111] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Alterations of the p53 gene have been found in many human and animal tumors, and ras mutations have been seen somewhat less frequently. Loss of p53 tumor suppressor activity has been implicated in multistage tumor promotion/progression after initiation by Ha-ras or Ki-ras activation. Whether p53 or ras alterations occur during promotion of neoplastic transformation in JB6 cells has not been reported. Using a series of mouse JB6 variants representing different stages of progression toward the tumor-cell phenotype, we investigated whether mutational activation of Ha-ras and mutational inactivation and altered expression of the p53 gene occurred during progression. We report here that neither point mutations of the Ha-ras or p53 genes nor p53 structural alterations were involved in this process. Although there was no significant difference in steady-state levels of p53 mRNA, an elevated level of immunoprecipitable p53 protein was observed in a subset of transformed cells. We also report the detection of a second 2.2-kb p53-hybridizing transcript. This transcript was not translated into p53 protein and may be a nuclear precursor of the mature message. Both p53-hybridizing transcripts were downregulated by prolonged 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment (24 h) regardless of the stage of progression. We conclude from this study that in JB6 variants (1) mutational activation of Ha-ras and inactivation of p53 are unlikely to be involved in preneoplastic progression; (2) increased amounts of p53 protein may be involved in a subset of transformed cells, possibly reflecting a longer half-life, as demonstrated in other systems; and (3) late downregulation of p53 mRNA but not protein expression may be a secondary response in the TPA-mediated signal transduction pathway.
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Affiliation(s)
- Y Sun
- Cell Biology Section, National Cancer Institute, Frederick, Maryland
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28
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Yoon HL, Marcus CB, Pfeifer RW. Induction of superoxide by 12-O-tetradecanoylphorbol-13-acetate and thapsigargin, a non-phorbol-ester-type tumor promoter, in peritoneal macrophages elicited from SENCAR and B6C3F1 mice: a permissive role for the arachidonic acid cascade in signal transduction. Mol Carcinog 1993; 7:116-25. [PMID: 8384457 DOI: 10.1002/mc.2940070210] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Local production of reactive oxygen intermediates, e.g., superoxide anion, by tumor promoter-stimulated inflammatory macrophages (MPs) may contribute significantly to tumor development in classical models of two-stage chemical-induced carcinogenesis in murine skin. In the studies reported herein, peritoneal MPs elicited from phorbol-ester-sensitive SENCAR mice demonstrated a time- and dose-dependent release of superoxide anion (4-6 nmol/10(6) cells) when stimulated by 200 nM 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro; MP superoxide response was significantly inhibited (50-70%) by preincubation with 40 microM 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine (H-7), a protein-kinase inhibitor. Alternatively, TPA-stimulated MPs derived from relatively resistant B6C3F1 mice generated negligible superoxide under the same conditions. A similar strain-dependent induction of superoxide was observed when MPs were stimulated with thapsigargin (TG), a tumor promoter previously shown to act independently of protein kinase C (PKC). TG-stimulated SENCAR MPs released a significant amount of superoxide (2-3 nmol/10(6) cells) that was not inhibited by H-7; MPs from B6C3F1 mice demonstrated negligible stimulation by TG. Preincubation of SENCAR MPs with 100 microM dibromoacetophenone, an inhibitor of phospholipase A2, completely suppressed the superoxide induced by TPA and TG stimulation. Like TPA, 50 microM 1-oleoyl-2-acetylglycerol, a diacylglycerol analogue and PKC activator, also induced a significant amount of superoxide from SENCAR MPs only. In parallel with the superoxide findings, TPA and TG stimulated significantly greater [3H]arachidonic acid release from prelabeled SENCAR MPs (a 32% and 48% increase, respectively, over unstimulated controls) relative to MPs from B6C3F1 mice. Two-dimensional gel-electrophoretic analysis indicated that TPA-induced phosphorylation of a 47-kDa protein (a presumed substrate for PKC previously linked to NADPH oxidase activation in guinea pig and human polymorphonuclear leukocytes) occurred in MPs from both SENCAR and B6C3F1 mice. Therefore, arachidonic acid production may be a common biochemical pathway by which phorbol-ester--and non-phorbol-ester--type tumor promoters activate MPs in SENCAR mice; such a response may be "permissive" for additive (or synergistic) interactions with PKC-driven signal pathways.
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Affiliation(s)
- H L Yoon
- Department of Pharmacology and Toxicology, School of Pharmacy and Pharmacal Sciences, Purdue University, West Lafayette, Indiana
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Bernstein LR, Bravo R, Colburn NH. 12-O-tetradecanoylphorbol-13-acetate--induced levels of AP-1 proteins: a 46-kDa protein immunoprecipitated by anti-fra-1 and induced in promotion-resistant but not promotion-sensitive JB6 cells. Mol Carcinog 1992; 6:221-9. [PMID: 1445622 DOI: 10.1002/mc.2940060308] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Neoplastic transformation and transcriptional activation by activator protein-1 (AP-1) complex are stimulated by tumor-promoting agents in promotion-sensitive (P+) but not promotion-resistant (P-) mouse epidermal JB6 cells in culture. This implicates AP-1 as a specific regulator of signal transduction pathways in the promotion phase of neoplastic transformation. We therefore hypothesized that the defective P- responsiveness may be due to limiting levels of AP-1 protein components in those cells. In this investigation, steady-state levels of AP-1 protein components were measured by immunoprecipitating proteins from 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated P+ and P- cells to discern what may limit the AP-1 response. Whereas the AP-1 proteins junB, junD, and fosB did not show differential basal or TPA-inducible levels in P+ and P- cells, a 46-kDa species precipitated by anti-fra-1 antibody was TPA-inducible in P- cells but not in P+ cells, and c-jun protein was present at higher levels in TPA-treated and untreated P+ cells than in P- cells. These data raise the possibility that the 46-kDa fra-1-related protein may be a negative modulator of AP-1 activity and suggest that elevated levels of this 46-kDa species and limiting levels of c-jun may significantly impair AP-1 function or transformation response in P- cells or both.
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Affiliation(s)
- L R Bernstein
- Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick Cancer Research and Development Center, MD 21702
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