1
|
Witt CJ, Gabel SP, Meisinger J, Werra G, Liu SW, Young MR. Interrelationship between Protein Phosphatase-2A and Cytoskeletal Architecture during the Endothelial Cell Response to Soluble Products Produced by Human Head and Neck Cancer. Otolaryngol Head Neck Surg 2016; 122:721-7. [PMID: 10793354 DOI: 10.1016/s0194-5998(00)70204-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Tumor neovascularization is necessary for the progressive development of all solid tumors, including head and neck squamous cell carcinomas (HNSCCs). The angiogenic process includes increased endothelial cell motility. Our prior studies have shown the importance of protein phos-phatase-2A (PP-2A) in restricting endothelial cell motility. Because motility is regulated by the polymerization/depolymerization of the cellular cytoskeleton, the present study defined the interrelationship between PP-2A and the cytoskeleton during endothelial cell responses to HNSCC-derived angiogenic factors. PP-2A was shown to colocalize with microtubules of unstimulated endothelial cells. However, exposure to HNSCC-derived products resulted in a more diffuse distribution of PP-2A staining and a loss of filamentous tubulin. The feasibility of pharmacologically preventing this cytoskeletal disorganization as a means of blocking tumor-induced angiogenesis was tested. This was accomplished by use of 1α,25-dihydroxyvitamin D3[1,25 (OH)2D3] and all- trans-retinoic acid to indirectly stimulate PP-2A activity through their capacity to elevated intracellular levels of the second messenger ceramide. Pretreatment of endothelial cells with either 1,25(OH)2D3or retinoic acid prevented the cytoskeletal disorganization that otherwise occurs in endothelial cells on exposure to HNSCC-derived products. These studies support the feasibility of using elevation of PP-2A to prevent the mor-phogenic component of the angiogenic process that is stimulated by HNSCC-derived factors.
Collapse
Affiliation(s)
- C J Witt
- Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center, Maywood, Illinois, USA
| | | | | | | | | | | |
Collapse
|
2
|
Prado R, Francis SO, Mason MN, Wing G, Gamble RG, Dellavalle R. Nonmelanoma skin cancer chemoprevention. Dermatol Surg 2011; 37:1566-78. [PMID: 21895847 DOI: 10.1111/j.1524-4725.2011.02108.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Renata Prado
- Department of Dermatology, School of Medicine, University of Colorado, Aurora, Colorado, USA.
| | | | | | | | | | | |
Collapse
|
3
|
Wright TI, Spencer JM, Flowers FP. Chemoprevention of nonmelanoma skin cancer. J Am Acad Dermatol 2006; 54:933-46; quiz 947-50. [PMID: 16713450 DOI: 10.1016/j.jaad.2005.08.062] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2004] [Revised: 09/24/2004] [Accepted: 08/15/2005] [Indexed: 11/16/2022]
Abstract
UNLABELLED Skin cancer is the most common cancer in human beings. The increased incidence of skin cancer has brought much attention to the process by which these tumors develop and how they can be prevented. Efforts have been made to educate the public about the importance of protecting skin from excessive ultraviolet light. Despite this work, the incidence of skin cancer continues to increase. Available compounds may be useful in the chemoprevention of skin cancer. Chemoprevention is defined as oral or topical use of dietary or pharmacologic agents to inhibit or reverse the development of cancer. Potential agents included are the retinoids; difluoromethylornithine; T4 endonuclease V; polyphenolic antioxidants, such as (-)-epigallocatechin gallate, found in green tea and grape seed extract; silymarin; isoflavone genestein; nonsteroidal anti-inflammatory drugs; curcumin; lycopene; vitamin E; beta-carotene; and selenium. Many of these agents are available over the counter as topical or oral preparations. LEARNING OBJECTIVE At the conclusion of this activity, participants should be familiar with the chemopreventive agents and their efficacy, as well as any significant side effects associated with them.
Collapse
Affiliation(s)
- Tina I Wright
- University of Florida College of Medicine, Gainesville, Florida, USA
| | | | | |
Collapse
|
4
|
Lago J, Santaclara F, Vieites JM, Cabado AG. Collapse of mitochondrial membrane potential and caspases activation are early events in okadaic acid-treated Caco-2 cells. Toxicon 2006; 46:579-86. [PMID: 16135376 DOI: 10.1016/j.toxicon.2005.07.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2005] [Accepted: 07/07/2005] [Indexed: 10/25/2022]
Abstract
Diarrhetic Shellfish Poisoning (DSP) results from the consumption of shellfish contaminated with okadaic acid (OA) or one of the dinophysistoxins (DTX). It has been reported that this toxin induces apoptosis in several cell models, but the molecular events involved in this process have not been clarified. In this report we studied intracellular signals induced by OA in Caco-2 cells: mitochondrial membrane potential, F-actin depolymerization, caspases activation, cell proliferation and cell membrane integrity. Results indicate that caspases-8 and -9 increased their activity after 30 min of OA treatment according to their role as initiator caspases. In contrast, activation of the downstream caspase-3 is a later event in the execution phase of apoptosis. Mitochondrial membrane potential changes are detected at 30 min of OA exposure indicating that this is an early response in the apoptotic cascade. F-actin depolymerization occurs after 24h of incubation with OA and this effect is significant at low doses of the toxin. LDH is released into the culture medium, although there is not PI uptake, indicative of a significant cell death in addition to apoptosis. Moreover, OA led to a dose- and time-dependent decrease in cellular proliferation.
Collapse
Affiliation(s)
- Jorge Lago
- Microbiology and Biotoxins Area, ANFACO-CECOPESCA, Campus Univ Vigo, 36310 Vigo (Pontevedra), Spain
| | | | | | | |
Collapse
|
5
|
Santaclara F, Lago J, Vieites JM, Cabado AG. Effect of okadaic acid on integrins and structural proteins in BE(2)-M17 cells. Arch Toxicol 2005; 79:582-6. [PMID: 15937665 DOI: 10.1007/s00204-005-0679-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 04/26/2005] [Indexed: 11/30/2022]
Abstract
Okadaic acid (OA), an algal toxin, is known to induce Diarrhetic Shellfish Poisoning and apoptosis in a variety of cell lines. One of the main targets of OA is the actin cytoskeleton which can be modulated by integrins and other structural proteins. In this paper we studied the role of these proteins and skeletal structures on OA-induced apoptosis in neuroblastoma cells. Results show that beta1 integrin and vinculin are down-regulated when cells were exposed to OA. We observed an interaction between talin and beta1 integrin that is impaired in OA treated cells.
Collapse
Affiliation(s)
- Francisco Santaclara
- Microbiology and Biotoxins Area, ANFACO-CECOPESCA, Campus Univ Vigo, 36310 Pontevedra, Spain.
| | | | | | | |
Collapse
|
6
|
Behrendt FF, Tolba RH, Overhaus M, Hirner A, Minor T, Kalff JC. Indocyanine green fluorescence measurement of intestinal transit and gut perfusion after intestinal manipulation. Eur Surg Res 2005; 36:210-8. [PMID: 15263826 DOI: 10.1159/000078855] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Accepted: 03/29/2004] [Indexed: 12/20/2022]
Abstract
BACKGROUND AND AIMS Postoperative ileus is a common and poorly understood problem of abdominal surgery. The aim of this study was to measure postoperative intestinal transit and to evaluate bowel wall perfusion by a novel in vivo indocyanine green (ICG)-fluorescence measurement following intestinal manipulation (IM). METHODS Rats underwent a simple intestinal manipulation. Myeloperoxidase-positive cells in the muscularis were stained with the Hanker-Yates reaction and quantified histochemically. Bowel wall perfusion was determined directly and 24 h postoperatively using a laser-fluorescence detection unit. Intestinal transit was visualized 24 h after IM. RESULTS IM resulted in a massive infiltration (155-fold) of neutrophils into the intestinal muscularis 24 h postoperatively. Bowel wall perfusion significantly decreased directly and 24 h following surgery (29 and 59%, respectively). Gastrointestinal transit was similarly impaired and showed a reduction to 40% of the control values 24 h after IM. CONCLUSION IM of the rat small intestine caused an impairment in bowel wall perfusion and microcirculation and a significant decrease in gastrointestinal transit. The ICG fluorescence measurement using the described system proved to be a simple and reliable method to evaluate intestinal transit and bowel wall microcirculation in vivo.
Collapse
Affiliation(s)
- F F Behrendt
- Department of Surgery, University of Bonn, Bonn, Germany
| | | | | | | | | | | |
Collapse
|
7
|
Romashko AA, Young MRI. Protein phosphatase-2A maintains focal adhesion complexes in keratinocytes and the loss of this regulation in squamous cell carcinomas. Clin Exp Metastasis 2004; 21:371-9. [PMID: 15554394 DOI: 10.1023/b:clin.0000046178.08043.f8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Studies assessed if the serine/threonine protein phosphatase-2A (PP-2A) maintains cytoskeletal integrity of normal keratinocytes and if this differs in malignant cells. Murine and human keratinocyte cell lines contained more PP-2A activity than did the murine SCC VII/SF squamous cell carcinoma cells or primary cultures of human head and neck squamous cell carcinoma (HNSCC) cells. Since tyrosine phosphorylation of the focal adhesion proteins paxillin and FAK is indicative of more stable focal adhesions, cells were immunostained for phosphotyrosine plus either paxillin or FAK, and then examined by confocal microscopy. In non-malignant keratinocytes, phosphotyrosine staining co-localized with paxillin and FAK. This co-localization occurred at the cell periphery in a pattern resembling focal adhesions. In contrast, the co-localization of phosphotyrosine with either paxillin or FAK along the cell periphery was almost absent in the SCC cells or in keratinocytes that were treated with okadaic acid to inhibit PP-2A activity. Consistent with this was a rounded cellular morphology with less extended processes as compared to control keratinocytes. These studies indicate PP-2A maintains the organization and tyrosine-phosphorylated state of the focal adhesion proteins FAK and paxillin, and that the loss of PP-2A activity results in a loss of cytoskeletal organization, as is seen in SCC.
Collapse
Affiliation(s)
- Alex A Romashko
- Department of Otolaryngology, Loyola University Stritch School of Medicine, Maywood, Illinois, USA
| | | |
Collapse
|
8
|
Affiliation(s)
- G Tim Bowden
- Department of Cell Biology and Anatomy, Arizona Cancer Center, The University of Arizona, 1515 North Campbell Avenue, Tucson, Arizona 85724-5024, USA.
| |
Collapse
|
9
|
Glenn HL, Jacobson BS. Cyclooxygenase and cAMP-dependent protein kinase reorganize the actin cytoskeleton for motility in HeLa cells. CELL MOTILITY AND THE CYTOSKELETON 2003; 55:265-77. [PMID: 12845600 DOI: 10.1002/cm.10128] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The adhesion of a cell to its surrounding matrix is a key determinant in many aspects of cell behavior. Adhesion consists of distinct stages : attachment, cell spreading, motility, and/or immobilization. Interrelated signaling pathways regulate these stages, and many adhesion-related signals control the architecture of the cytoskeleton. The various cytoskeletal organizations then give rise to the specific stages of adhesion. It has been shown that arachidonic acid acts at a signaling branch point during cell attachment. Arachidonic acid is metabolized via lipoxygenase to activate actin polymerization and cell spreading. It is also metabolized by cyclooxygenase to generate small actin bundles. We have used confocal microscopy and indirect immunofluorescence to investigate the structure of these cyclooxygenase dependent actin bundles in HeLa cells. We have also employed cell migration assays and pharmacological modulation of cyclooxygenase and downstream signals. The results indicate that cyclooxygenase and PKA stimulate the formation of actin bundles that contain myosin II and associate with small focal adhesions. In addition, we demonstrate that this cytoskeletal organization correlates with increased cell motility.
Collapse
Affiliation(s)
- Honor L Glenn
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003l, USA.
| | | |
Collapse
|
10
|
Leira F, Alvarez C, Cabado AG, Vieites JM, Vieytes MR, Botana LM. Development of a F actin-based live-cell fluorimetric microplate assay for diarrhetic shellfish toxins. Anal Biochem 2003; 317:129-35. [PMID: 12758250 DOI: 10.1016/s0003-2697(02)00230-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A new cytotoxicity assay for detection and quantitation of diarrhetic shellfish toxins (DSP) is presented. This assay is based upon fluorimetric determination of F-actin depolymerization induced by okadaic acid (OA)-class compounds in the BE(2)-M17 neuroblastoma cell line. No interferences were observed with other marine toxins such as saxitoxin, domoic acid, or yessotoxin, thus indicating a good specificity of the assay as expected by the direct relationship between protein phosphatase inhibition and cytoskeletal changes. The proposed method is rapid (<2h) and shows a linear response in the range of 50-300 nM OA. The detection limit of the assay for crude methanolic extracts of bivalves lies between 0.2 and 1.0 microg OA per gram of digestive glands, depending on the type of samples (fresh or canned), thus being similar to that of the mouse bioassay. The performance of this assay has been evaluated by comparative analysis of 32 toxic mussel samples by the F-actin assay, mouse bioassay, HPLC and PP2A inhibition assay. Results obtained by the F-actin method showed no differences with HPLC and significant correlation with PP2A inhibition assay (r(2)=0.71). No false negative results were obtained with this new cell assay, which also showed optimum reproducibility.
Collapse
Affiliation(s)
- F Leira
- ANFACO-CECOPESCA, Campus Universitario de Vigo, Vigo 36310, Spain.
| | | | | | | | | | | |
Collapse
|
11
|
Takano T, Cybulsky AV, Cupples WA, Ajikobi DO, Papillon J, Aoudjit L. Inhibition of cyclooxygenases reduces complement-induced glomerular epithelial cell injury and proteinuria in passive Heymann nephritis. J Pharmacol Exp Ther 2003; 305:240-9. [PMID: 12649375 DOI: 10.1124/jpet.102.043604] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the passive Heymann nephritis (PHN) model of rat membranous nephropathy, complement induces glomerular epithelial cell injury and proteinuria, which is partially mediated by eicosanoids. Glomerular cyclooxygenase (COX)-1 and -2 are up-regulated in PHN and contribute to prostanoid generation. In the current study, we address the role of COX isoforms in proteinuria, using the nonselective COX inhibitor indomethacin and the COX-2-selective inhibitor 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl)phenyl-2(5H)-furanone (DFU). Four groups of rats with PHN were treated twice daily, from day 7 through 14 with vehicle, 1 mg/kg DFU, 10 mg/kg DFU, or 2 mg/kg indomethacin. Vehicle-treated rats with PHN showed significant proteinuria on day 14 (163 +/- 15 mg/d, n = 19), compared with normal rats (10 +/- 4 mg/d, n = 3, p < 0.001). Treatment with DFU (1 or 10 mg/kg) reduced proteinuria significantly (by ~33%), compared with vehicle, but to a lesser extent than indomethacin (56% reduction). Glomerular eicosanoid generation was reduced significantly in the DFU and indomethacin groups, compared with vehicle. There were no significant differences among vehicle- or DFU-treated groups in [(3)H]inulin clearance, or in glomerular expression of COX-1 and -2. DFU did not affect the autologous immune response. In cultured rat glomerular epithelial cells, COX inhibition reduced complement-induced cytotoxicity, and this reduction was reversed by the thromboxane A(2) analog 9,11-dideoxy-9alpha,11alpha-methanoepoxyprostaglandin F(2alpha) (U46619). Thus, in experimental membranous nephropathy, selective inhibition of COX-2 reduces proteinuria, without adversely affecting renal function. However, inhibition of both COX-1 and -2 is required to achieve a maximum cytoprotective and antiproteinuric effect.
Collapse
Affiliation(s)
- Tomoko Takano
- Department of Medicine, McGill University Health Centre, McGill University, Montreal, Quebec, Canada.
| | | | | | | | | | | |
Collapse
|
12
|
Glenn HL, Jacobson BS. Arachidonic acid signaling to the cytoskeleton: the role of cyclooxygenase and cyclic AMP-dependent protein kinase in actin bundling. CELL MOTILITY AND THE CYTOSKELETON 2002; 53:239-50. [PMID: 12211105 DOI: 10.1002/cm.10072] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cell adhesion to the extracellular matrix via integrins is a primary regulatory mechanism for numerous aspects of normal cellular function. However, disruption of this interaction can result in pathology. For example, one characteristic of transformed cells is loss of adhesion dependence for viability. Adhesion also is a necessary step in tumor metastasis. It has been shown previously, in HeLa cells, that cell attachment to a gelatin-coated substrate results in the release of arachidonic acid, which is metabolized by lipoxygenase. A subsequent cascade of lipid second messengers activates protein kinase C, which triggers actin polymerization leading to cell spreading. We now demonstrate by inhibitor studies and biochemical analysis, a parallel branch of arachidonic acid signaling that reorganizes the actin cytoskeleton into small bundles. This branch of the pathway is initiated by cyclooxygenase, which generates prostaglandins and causes the downstream activation of cyclic AMP-dependent protein kinase. This work elucidates a system of interacting signals in which arachidonic acid functions at a branch point in cytoskeletal signaling. The lipoxygenase branch provides polymerized actin; these actin filaments act as a substrate for the cylooxygenase branch to generate actin bundles.
Collapse
Affiliation(s)
- Honor L Glenn
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, 01003, USA
| | | |
Collapse
|
13
|
Chang MC, Uang BJ, Wu HL, Lee JJ, Hahn LJ, Jeng JH. Inducing the cell cycle arrest and apoptosis of oral KB carcinoma cells by hydroxychavicol: roles of glutathione and reactive oxygen species. Br J Pharmacol 2002; 135:619-30. [PMID: 11834609 PMCID: PMC1573166 DOI: 10.1038/sj.bjp.0704492] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2001] [Revised: 11/08/2001] [Accepted: 11/08/2001] [Indexed: 11/08/2022] Open
Abstract
Hydroxychavicol (HC; 10 - 50 microM), a betel leaf component, was found to suppress the 2% H(2)O(2)-induced lucigenin chemiluminescence for 53 - 75%. HC (0.02 - 2 microM) was also able to trap superoxide radicals generated by a xanthine/xanthine oxidase system with 38 - 94% of inhibition. Hydroxyl radicals-induced PUC18 plasmid DNA breaks was prevented by HC (1.6 - 16 microM). A 24-h exposure of KB cells to HC (0.5, 1 mM) resulted in 54 - 74% cell death as analysed by a 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. HC (10, 50 microM) further suppressed the growth of KB cells (15 and 76%, respectively). Long-term colony formation of KB cells was inhibited by 51% with 10 microM HC. Pretreatment of KB cells with 100 microM HC inhibited the attachment of KB cells to type I collagen and fibronectin by 59 and 29%, respectively. Exposure of KB cells to 0.1 mM HC for 24 h resulted in cell cycle arrest at late S and G2/M phase. Increasing the HC concentration to 0.25 and 0.5 mM led to apoptosis as revealed by detection of sub-G(0)/G(1) peaks with a concomitant decrease in the number of cells residing in late S and G(2)/M phase. Inducing the apoptosis of KB cells by HC was accompanied by marked depletion in reduced form of GSH (>0.2 mM) and the increasing of reactive oxygen species production (>0.1 mM) as analysed by CMF- and DCF-single cell fluorescence flow cytometry. These results indicate that HC exerts antioxidant property at low concentration. HC also inhibits the growth, adhesion and cell cycle progression of KB cells, whereas its induction of KB cell apoptosis (HC>0.1 mM) was accompanied by cellular redox changes.
Collapse
Affiliation(s)
- M C Chang
- Team of Biomedical Science, Chang-Gung Institute of Nursing, 251 Wen-Hwa 1st Road, Kwei-Shan, Taoyuan, Taiwan
| | - B J Uang
- Department of Chemistry, National Tsing Hua University, Hsin-Chu, Taiwan
| | - H L Wu
- Department of Chemistry, National Tsing Hua University, Hsin-Chu, Taiwan
| | - J J Lee
- Laboratory of Dental Pharmacology & Toxicology, Graduate Institute of Clinical Dental Science, National Taiwan University and Hospital, Taipei, Taiwan
| | - L J Hahn
- Laboratory of Dental Pharmacology & Toxicology, Graduate Institute of Clinical Dental Science, National Taiwan University and Hospital, Taipei, Taiwan
| | - J H Jeng
- Laboratory of Dental Pharmacology & Toxicology, Graduate Institute of Clinical Dental Science, National Taiwan University and Hospital, Taipei, Taiwan
| |
Collapse
|
14
|
Thompson EJ, Gupta A, Vielhauer GA, Regan JW, Bowden GT. The growth of malignant keratinocytes depends on signaling through the PGE(2) receptor EP1. Neoplasia 2001; 3:402-10. [PMID: 11687951 PMCID: PMC1506208 DOI: 10.1038/sj.neo.7900182] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2001] [Accepted: 05/24/2001] [Indexed: 11/09/2022] Open
Abstract
Recent discoveries shed light on the importance of prostaglandin (PG) production in the development of skin cancer. Work by Fischer et al. demonstrates that skin tumor promotion caused by ultraviolet B radiation can be decreased by up to 89% by blocking cyclooxygenase-2 (COX-2) with the drug Celecoxib. A similar study showed that Celecoxib can decrease new tumor formation by 44% in mice that already have tumors. These studies demonstrate the importance of COX-2 and PGs in the development of squamous cell carcinoma. We have explored growth signaling in a model of skin tumor progression. Because changes in PG production have been implicated in skin carcinogenesis, we examined this pathway. We found that malignant cell lines secrete more prostaglandin E(2) (PGE(2)) than the parental cells. We observed increased expression of COX-1 and -2. We also found that these cells express the PGE(2) receptors EP1 and EP4. When the cells are grown in the presence of indomethacin, the growth rate of the malignant cells is decreased. This effect can be reversed by addition of PGE(2) or an EP1 agonist to the medium. Thus, we have shown that skin tumor cells depend in part on PGE(2) signaling through the EP1 prostanoid receptor for their in vitro growth.
Collapse
Affiliation(s)
- E J Thompson
- Department of Pharmacology and Toxicology, The University of Arizona, Tucson, AZ 85724, USA
| | | | | | | | | |
Collapse
|
15
|
Leira F, Alvarez C, Vieites JM, Vieytes MR, Botana LM. Study of cytoskeletal changes induced by okadaic acid in BE(2)-M17 cells by means of a quantitative fluorimetric microplate assay. Toxicol In Vitro 2001; 15:277-82. [PMID: 11566549 DOI: 10.1016/s0887-2333(01)00021-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The diarrhogenic activity of the marine toxin okadaic acid (OA) has been associated to its actin-disrupting effect, which could reflect the loosening of tight junctions in vivo. In this report, we present results obtained using a fluorimetric microplate assay for quantitative measurements of OA-induced changes on F-actin pools in BE(2)-M17 cells. The proposed method shows important advantages over classical methods in terms of rapidity, sensitivity (less than 5000 cells per well) and reproducibility, thus providing a very useful tool for studying F-actin levels in living cells. Results obtained demonstrate a time- and dose-dependent decrease of F-actin pools (IC(50)=100 nM at 1 h) in OA-treated cells, which was partly counteracted by TPA, H89, forskolin, wortmannin, ionomycin and orthovanadate at early stages, but remained unaffected after 24 h of incubation. Cells exposed for 1 h to 1 nM OA showed a slight increase of F-actin pools (1.5-fold), which was blocked by genistein and lavendustin A, thus suggesting a role for tyrosine kinases-dependent pathways in OA-induced polymerization at low concentrations. These results suggest direct interactions of Ser/Thr protein phosphatases with actin-binding proteins in the regulation of actin polymerization, thus indicating that disruption of cytoskeletal structure may be a key mechanism of OA-induced diarrhea.
Collapse
Affiliation(s)
- F Leira
- ANFACO-CECOPESCA, Campus Universitario de Vigo, 36310 Vigo, Spain.
| | | | | | | | | |
Collapse
|
16
|
Witt CJ, Gabel SP, Meisinger J, Werra G, Liu SW, Young MR. Interrelationship between protein phosphatase-2A and cytoskeletal architecture during the endothelial cell response to soluble products produced by human head and neck cancer. Otolaryngol Head Neck Surg 2000. [PMID: 10793354 DOI: 10.1067/mhn.2000.105186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Tumor neovascularization is necessary for the progressive development of all solid tumors, including head and neck squamous cell carcinomas (HNSCCs). The angiogenic process includes increased endothelial cell motility. Our prior studies have shown the importance of protein phosphatase-2A (PP-2A) in restricting endothelial cell motility. Because motility is regulated by the polymerization/depolymerization of the cellular cytoskeleton, the present study defined the interrelationship between PP-2A and the cytoskeleton during endothelial cell responses to HNSCC-derived angiogenic factors. PP-2A was shown to colocalize with microtubules of unstimulated endothelial cells. However, exposure to HNSCC-derived products resulted in a more diffuse distribution of PP-2A staining and a loss of filamentous tubulin. The feasibility of pharmacologically preventing this cytoskeletal disorganization as a means of blocking tumor-induced angiogenesis was tested. This was accomplished by use of 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] and all-trans -retinoic acid to indirectly stimulate PP-2A activity through their capacity to elevated intracellular levels of the second messenger ceramide. Pretreatment of endothelial cells with either 1,25(OH)(2)D(3) or retinoic acid prevented the cytoskeletal disorganization that otherwise occurs in endothelial cells on exposure to HNSCC-derived products. These studies support the feasibility of using elevation of PP-2A to prevent the morphogenic component of the angiogenic process that is stimulated by HNSCC-derived factors.
Collapse
Affiliation(s)
- C J Witt
- Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center, Maywood, Illinois, USA
| | | | | | | | | | | |
Collapse
|
17
|
Hangan-Steinman D, Ho WC, Shenoy P, Chan BMC, Morris VL. Differences in phosphatase modulation of α4 β1 and α5 β1 integrin-mediated adhesion and migration of B16F1 cells. Biochem Cell Biol 1999. [DOI: 10.1139/o99-050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It is well established that a biphasic relationship exists between the adhesive strength of β1 integrins and their ability to mediate cell movement. Thus, cell movement increases progressively with adhesive strength, but beyond a certain point of optimal interaction, cell movement is reduced with further increases in adhesive function. The interplay between the various kinase and phosphatase activities provides the balance in β1 integrin-mediated cell adhesion and migration. In the present study, the significance of protein tyrosine phosphatases (PTP) and ser/thr protein phosphatases (PP) in α4β1 and α5β1 integrin-mediated mouse melanoma B16F1 cell anchorage and migration on fibronectin was characterized using phosphatase inhibitors. At low fibronectin concentration, α5β1 functioned as the predominant receptor for cell movement; a role for α4β1 in B16F1 cell migration increased progressively with fibronectin concentration. Treatment of B16F1 cells with PTP inhibitors, sodium orthovanadate (Na3VO4) and phenylarsine oxide (PAO), or PP-1/2A inhibitor, okadaic acid (OA), abolished cell movement. Inhibition of cell movement by PAO and OA was associated by a reduction in the adhesive strength of α4β1 and α5β1. In contrast, treatment of B16F1 cells with Na3VO4 resulted in selective stimulation of the adhesive function of α5β1, but not α4β1. Therefore, our results demonstrate that (i) both PTP and PP-1/2A have roles in cell movement, (ii) modulation of cell movement by PTP and PP-1/2A may involve either a stimulation or reduction of β1 integrin adhesive strength, and (iii) distinct phosphatase-mediated signaling pathways for differential regulation of the various β1 integrins exist. Key words: phosphatases, integrins, cell movement, cell adhesion.
Collapse
|
18
|
Young MR. Protein phosphatases-1 and -2A regulate tumor cell migration, invasion and cytoskeletal organization. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 407:311-8. [PMID: 9321969 DOI: 10.1007/978-1-4899-1813-0_46] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The role of protein kinase A (PKA) and protein phosphatases (PP) -1 and -2A in regulating the metastatic phenotype of Lewis lung carcinoma (LLC) cells was evaluated. The metastatic LLC-LN7 cells were more motile and invasive than were nonmetastatic LLC-C8 cells. Compared to the nonmetastatic cells, the LLC-LN7 cells had increased PKA activity and a deficiency in PP-2A. Nonmetastatic LLC-C8 cells became migratory and invasive when PP-1 and P-2A activities were inhibited with okadaic acid. This stimulation of LLC-C8 motility was tempered by PKA inhibition. Also examined was if the okadaic acid-stimulated LLC-C8 motility was associated with a change in the cytoskeletal organization to that typical of metastatic cells. Treatment of nonmetastatic LLC-C8 cells with okadaic acid caused a redistribution of F-actin toward the periphery of the cells, and eventually to a loss of the filamentous actin network. All of these effects were reversed upon removal of okadaic acid. Our results show that PP-1/2A maintain reduced motility and increased cytoskeletal organization within nonmetastatic LLC cells.
Collapse
Affiliation(s)
- M R Young
- Research Service (151-Z2) Hines V.A. Hospital, IL 60141, USA
| |
Collapse
|