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Similar and Divergent Patterns in the Regulation of Matrix Metalloproteinase-1 (MMP-1) and Tissue Inhibitor of MMP-1 Gene Expression in Benign and Malignant Human Thyroid Cells¹

Endocrine Research Unit (S.K., Z.K.), and Department of Pathology (M.B.R.), Carmel Medical Center and Faculty of Medicine (S.K., M.B.R., Z.K.), Technion, Haifa 34362, Israel

Address all correspondence and requests for reprints to: Z. Kraiem, Ph.D., Endocrine Research Unit, Carmel Medical Center, 7 Michal Street, Haifa 34362, Israel. E-mail: zkraiem{at}tx.technion.ac.il

	Abstract

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An imbalance between the activity of matrix metalloproteinases (MMPs) (proteolytic enzymes that degrade protein components of the extracellular matrix) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), may be one of the mechanisms responsible for tumor cell invasion. We have investigated the regulation of MMP-1 and TIMP-1 gene expression in benign and malignant (follicular, anaplastic, and papillary) human thyroid cells. As expected of cells with invasive potential, detectable MMP-1 messenger RNA (mRNA) levels were observed in malignant cells under basal conditions, in contrast to undetectable levels in benign cells. Exposure of these cells, for 1 h, to the active phorbol ester, phorbol 12-myristate 13-acetate (TPA, 100 nmol/L), acting via protein kinase C (PKC), elicited an increase in MMP-1 mRNA, with a peak stimulation after a 3- to 4-h culture period. Epidermal growth factor (EGF, 25 ng/mL), however, acting via protein tyrosine kinase (PTK), stimulated such gene expression in malignant cells but failed to do so in benign cells. TIMP-1 mRNA was not significantly altered by the TPA-PKC, EGF-PTK, or TSH-protein kinase A (PKA) pathways in malignant cells. In benign cells, however, TPA induced a small, though significant, increase in TIMP-1. The MMP-1 stimulation by EGF and lack of TPA-induced rise in TIMP-1 in malignant cells, in sharp contrast to the effects obtained in benign thyrocytes, seems to indicate that the MMP:TIMP balance favors a more extensive extracellular matrix protein breakdown by malignant thyrocytes, as expected of cells exhibiting invasive capacity. TSH (10–500 µU/mL) failed to significantly influence basal MMP-1 or TIMP-1 mRNA levels, but it caused a dose-dependent inhibition in TPA- and EGF-induced MMP-1 mRNA in malignant cells, and TPA-stimulated MMP-1 and TIMP-1 in benign cells. The repressive action of TSH on MMP-1 mRNA was mimicked by forskolin and 8-bromo-cAMP and was abrogated by the PKA inhibitor, H-89, suggesting that the TSH inhibitory action is PKA-mediated.

In conclusion, the present study provides novel data on MMP-1 and TIMP-1 gene expression and their modulation by the major signal transduction pathways operating in human thyroid cells. Similar and divergent patterns have emerged in the regulation of such gene expression in benign and malignant human thyrocytes, in many instances in accord with the concept of MMP playing the role of stimulating, and TIMP inhibiting, cell invasion. Although MMP-1 may be just one of the many factors responsible for tumor cell invasion, the present findings demonstrating the possibility, at least in vitro, of repressing MMP gene expression may have important clinical ramifications.

	Introduction

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THE MATRIX metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade protein components of the extracellular matrix. Normal physiological processes involving tissue remodeling, such as morphogenesis and angiogenesis, as well as a number of pathological conditions whose pathogenesis involves matrix degradation, such as arthritis and tumor invasion, are believed to result from an imbalance between the activity of these proteinases and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) (reviewed in Refs. 1, 2). The enhanced proteolytic activity associated with tumor spread (local invasion and metastasis) could be the result of increased MMP activity and/or the consequence of reduced activity of their inhibitors (TIMPs). MMPs may thus function as metastasis-promoting proteins that induce tumor cell invasion, whereas TIMPs may act as metastasis-suppressing proteins.

Expression of the MMP-1 gene is activated by the transcription factor AP-1 (3). AP-1 is a dimer whose subunits consist of the protein products encoded by the jun and fos gene family. We have previously reported that the major signal transduction pathways regulating human thyroid function and growth, the protein kinase A, C, and tyrosine kinase (PKA, PKC, and PTK) cascades exhibit antagonistic interactions with regard to c-jun and c-fos gene expression in human thyroid cells (4). TSH, acting via cAMP-PKA, inhibited c-jun and c-fos gene expression induced by either phorbol 12-myristate 13-acetate (TPA), acting via PKC, or epidermal growth factor (EGF), acting via tyrosine kinase, in human thyroid cells (4). Because, as mentioned above, c-jun and c-fos dimer products (i.e. AP-1) activate MMP-1 gene expression, it was logical to test whether the antagonistic interactions between the pathways noted above would also be reflected in the expression of the MMP gene in these cells. Because MMP activity is mainly regulated at the level of gene transcription and interaction with specific inhibitors (TIMPs), we investigated MMP-1 and TIMP-1 gene expression under the influence of the above three pathways in benign and malignant human thyroid cells.

	Materials and Methods

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Cell culture

The method of preparation of benign human thyroid cells from tissue obtained at thyroidectomy from patients with benign colloid nodules, has been previously described in detail (5, 6). Regarding the malignant cells, the following well-established and extensively studied human thyroid carcinoma cell lines, kindly provided by Dr. G. J. F. Juillard (University of California at Los Angeles, Los Angeles, CA), were used: MRO 87–1 (follicular), ARO 81–1 (anaplastic), and NPA (papillary). These cell lines have TSH receptors but may have postreceptor defects (7). For individual experiments, the benign or malignant cells were plated onto Petri dishes in RPMI-1640 medium and 10% FCS. The following day, the medium was replaced with serum-free medium (RPMI-1640 and 0.3% BSA) and cultured for an additional 2 days, at the end of which, medium was replaced with serum-free medium (RPMI-1640 and 0.3% BSA) containing the test agent (e.g. TPA, EGF, TSH). Control consisted of serum-free medium alone.

RNA isolation and analysis

The method for determination, by Northern blot of messenger RNA (mRNA) MMP-1 and TIMP-1 levels in cultured human thyrocytes, was the same as we previously reported for c-jun and c-fos mRNA in the same cells (4). Total RNA was extracted from thyroid cells with Tri-reagent. The RNA samples were denatured by heating at 65 C for 15 min in 2 mol/L formaldehyde-50% formamide and fractionated by electrophoresis (15 µg/lane) in 1% agarose gel containing 0.66 mol/L formaldehyde and 3-(N-morpholino)propane-sulfonic acid buffer. After separation, the RNA was transferred to blotting membrane. MMP-1 and TIMP-1 mRNA were detected by hybridization with oligonucleotide probes 5'-end-labeled with ³²P, autoradiographed at -70 C, and quantitated by densitometry. The densitometric values were normalized to those for glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Probing, stripping, and reprobing of MMP-1, TIMP-1, and GAPDH were performed on the same membrane.

Each experiment was repeated at least three times using, in case of benign cells, preparations obtained from separate patients for each experiment. The mRNA data shown in the figures and in the text are GAPDH-normalized. Statistical analysis of the data was performed using Student’s t test when two treatments were compared and ANOVA when more than two treatments were evaluated (e.g. dose-dependent responses). P < 0.05 was considered significant.

Materials

Materials needed for cell culture and all agents used were obtained as described previously (5, 6). For RNA isolation and analysis, the following sources were used: Tri-reagent from Molecular Research Center, Inc. (Cincinnati, OH); blotting membranes from Sartorius (Gottingen, Germany); MMP-1 and GAPDH oligonucleotide probes from Oncogene Science, Inc. (Cambridge, MA) and TIMP-1 oligonucleotide probe from Biognostik (Gottingen, Germany). All other materials were from Sigma Chemical Co. (St. Louis, MO).

	Results

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Time-dependent stimulation of MMP-1 mRNA by TPA and EGF showed a peak, after 3–4 h, in the benign cells and in all three cell lines (see, for example, Fig. 1). In contrast, TIMP-1 mRNA was not significantly altered by these agents in all three cell lines (see for example, Fig. 1) but was altered in the benign cells (see below). Addition of the protein synthesis inhibitor, cycloheximide, inhibited the TPA- and EGF-induced MMP-1 mRNA stimulation (Fig. 2).

View larger version (23K): [in this window] [in a new window]   Figure 1. Time course of MMP-1 and TIMP-1 mRNA levels in cultured human thyroid follicular carcinoma cells exposed to TPA (A) or anaplastic cells exposed to EGF (B). TPA (10-7 mol/L) or EGF (25 ng/mL) was added to the culture medium for 1 h, the medium was then replaced with fresh medium alone (RPMI-1640 and 0.3% BSA), and MMP-1 and TIMP-1 mRNA were measured, after 1–4 h, by Northern blot followed by densitometry. Each bar represents the mean ± SE of four experiments.

View larger version (38K): [in this window] [in a new window]   Figure 2. Effect of cycloheximide (CHX) on TPA- or EGF-induced MMP-1 and TIMP-1 mRNA in cultured human thyroid follicular carcinoma cells. Cycloheximide (10 µg/mL) was added to the culture medium, and 30 min later, TPA (10-7 mol/L) or EGF (25 ng/mL) was added for an additional hour. The medium was then replaced with fresh medium (RPMI-1640 and 0.3% BSA) together with cycloheximide (10 µg/mL), and MMP-1 and TIMP-1 mRNA were measured, 4 or 5 h later, by Northern blot. The autoradiograph shown is representative of three experiments.

View larger version (58K): [in this window] [in a new window]   Figure 3. Effects of TSH, 8-bromo-cAMP (8-Br-cAMP), or forskolin (Fsk), alone and together with TPA, on MMP-1 and TIMP-1 mRNA levels in cultured human thyroid anaplastic cells. TPA (10-7 mol/L) was added in the absence or presence of TSH (0.01–1 mU/mL), 8-Br-cAMP (1 mmol/L), or forskolin (20 µmol/L) added 30 min before the addition of TPA. Culture was continued for an additional hour, the medium was then replaced with fresh medium alone (RPMI-1640 and 0.3% BSA), and MMP-1 and TIMP-1 mRNA were measured, 3 h later, by Northern blot followed by densitometry. Each bar represents the mean ± SE of four experiments. The autoradiograph shown is that of a representative experiment.

View larger version (54K): [in this window] [in a new window]   Figure 4. Effects of TSH or 8-Br-cAMP, alone and together with EGF, on MMP-1 and TIMP-1 mRNA levels in cultured human thyroid follicular carcinoma cells. EGF (25 ng/mL) was added in the absence or presence of TSH (0.01–1 mU/mL) or 8-Br-cAMP (1 mmol/L) added 30 min before the addition of EGF. Culture was continued for an additional hour, the medium was then replaced with fresh medium alone (RPMI-1640 and 0.3% BSA), and MMP-1 and TIMP-1 mRNA were measured, 3 h later, by Northern blot followed by densitometry. Each bar represents the mean ± SE of four experiments. The autoradiograph shown is that of a representative experiment.

View larger version (15K): [in this window] [in a new window]   Figure 5. Effects of H-89 on EGF and TSH- or EGF and 8-bromo-cAMP (8Br)-induced MMP-1 and TIMP-1 mRNA levels in cultured human thyroid anaplastic cells. EGF (25 ng/mL) was added in the absence or presence of TSH (0.5 mU/mL) or 8-Br-cAMP (1 mmol/L) added 30 min before the addition of EGF, or H-89 (10 mmol/L) added 30 min before the addition of TSH or 8-Br-cAMP. Culture was continued for an additional hour, the medium was then replaced with fresh medium alone (RPMI-1640 and 0.3% BSA), and MMP-1 and TIMP-1 mRNA were measured, 3 h later, by Northern blot followed by densitometry. Each bar represents the mean ± SE of three experiments.

View larger version (45K): [in this window] [in a new window]   Figure 6. Effects of TSH or forskolin (FSK), alone and together with EGF or TPA, on MMP-1 and TIMP-1 mRNA levels in cultured human thyroid benign cells. EGF (25 ng/mL) or TPA (10-7 mol/L) was added in the absence or presence of TSH (0.5 mU/mL) or forskolin (20 µmol/L) added 30 min before the addition of EGF or TPA. Culture was continued for an additional hour, the medium was then replaced with fresh medium alone (RPMI-1640 and 0.3% BSA), and MMP-1 and TIMP-1 mRNA were measured, 3 h later, by Northern blot followed by densitometry. Each bar represents the mean ± SE of five experiments, using cell preparations obtained from separate patients for each experiment. The autoradiograph shown is that of a representative experiment.

	Discussion

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Only a few studies have examined MMP expression in thyroid cells. MMP-1 was found to be expressed in human thyroid carcinoma cells (8) and in fibrous capsules of papillary carcinomas (9), and MMP-2 in thyroid tumors (10) and stromal fibroblasts adjacent to invasive thyroid tumors (11). Moreover, the invasive capacity of human follicular thyroid cells correlated with increased synthesis of MMPs and ß1 integrins, i.e. receptors to basement membrane and extracellular matrix components (12). TPA was found to stimulate MMP-1 gene expression in human thyroid anaplastic cells (13), similar to the increase we observed in malignant and benign thyrocytes. It should be noted, however, that in the latter study (13), as in most other studies on TPA-induced MMP, the cells were exposed to the phorbol ester for as long as 24 h, a time period that has been shown to induce PKC down-regulation (14), unlike the 90-min exposure of thyrocytes to TPA in our experiments.

In agreement with the TPA-stimulated c-jun and c-fos mRNA we had observed in human thyrocytes (4), the phorbol ester augmented the c-jun and c-fos (i.e. AP-1)-dependent MMP-1 gene expression in these cells. EGF (whose action has not yet been reported in this regard in thyroid cells) only managed, however, to stimulate such gene expression in malignant cells but failed, at the same concentration, to do so in benign cells. This is contrary to the stimulation of c-jun and c-fos elicited by EGF we observed in the same (benign) cells at the same EGE concentration (4), i.e. genes which encode the AP-1 transcription factor known to activate MMP-1 expression (3). The underlying mechanism(s) that may explain this discrepancy between c-jun/c-fos (i.e. AP-1) and MMP-1 expression in benign cells is presently unknown, but the following possibilities could be proposed: 1) The AP-1 complex is not alone in its role as an MMP transcriptional activator, and other transcriptional factors are necessary. Indeed, both PEA3 and NFB sites on MMP promoters have been shown to cooperate functionally with AP-1 sites in MMP transcription (reviewed in Ref. 15). 2) Stimulation of Jun B, a member of the Jun protein family, which has been shown to inhibit the c-Jun-induced activation of the MMP-1 promoter (16) and MMP-1 gene expression (17). 3) Lack of appropriate posttranslational modification(s) of Jun and/or Fos necessary for AP-1 activation (reviewed in Ref. 18). The above possibilities need of course to be substantiated by experimental verification in our system.

TPA elicited a small, though significant, increase in TIMP-1 mRNA in benign cells. In malignant cells, however, TIMP mRNA was not significantly altered by the TPA-, EGF- or TSH/PKA-induced pathways. The only other report on TIMP expression in thyroid cells noted a TPA-induced increase in TIMP-1 expression in malignant cells (13). The long duration of exposure of thyrocytes to the phorbol ester in that study (13) (24 h, compared with 1 h in our experiments) is known to induce, as mentioned above, PKC down-regulation (14) and this may possibly explain the discrepancy with our data.

The MMP-1 stimulation by EGF and lack of TPA-induced rise in TIMP-1 in malignant cells, in sharp contrast to the effect in benign thyrocytes, seems to indicate that the MMP-TIMP balance favors a more extensive extracellular matrix protein breakdown by malignant thyrocytes, as expected of cells exhibiting invasive capacity. It is realized that caution must be exercised regarding generalizations about thyroid malignant cell behavior based on three cell lines. Nevertheless, the results are in accordance with the demonstration that EGF enhances the invasive capacity of human thyroid malignant cells (19). Moreover, when comparing the data of the benign with those of the malignant thyrocytes, it should be kept in mind that although the design and conditions of the experiments were the same for both benign and malignant cells, the former derived from primary culture whereas the latter were established cell lines.

TSH failed to significantly influence basal MMP-1 or TIMP-1 mRNA levels in malignant or benign cells but managed to inhibit TPA- and EGF-induced MMP-1 mRNA in malignant cells and TPA-stimulated MMP-1 and TIMP-1 in benign cells. The effects of TSH, alone and together with TPA and EGF, were mimicked by the PKA stimulators, forskolin and 8-bromo-cAMP, and abrogated by the PKA inhibitor, H-89, suggesting that the TSH inhibitory action is PKA-mediated. The data are consistent with our previous findings (4), using the same cells, of similar antagonistic interactions between TSH-PKA on the one hand and PKC or tyrosine kinase on the other, with regard to c-jun and c-fos, i.e. genes encoding an activator of MMP-1 gene expression, AP-1 (3).

This is the first report describing the influence of TSH or PKA action on MMP/TIMP induction in thyroid cells, and the findings are in agreement with the lack of effect of PKA alone on MMP expression in other cell systems (reviewed in Ref. 3). Our results, that TPA (i.e. PKC) enhances MMP-1 expression whereas PKA was devoid of any such action, agree with the finding that PKC, but not PKA, was shown to be capable of stimulating human thyrocyte invasive ability (20). In the latter study (20), TSH was used as a PKC stimulator because, at high concentrations, thyrotropin seems able to activate the PKC pathway in human thyrocytes (21). Our data provide the first demonstration of cross-talk between the PKA and EGF (i.e. tyrosine kinase) pathways, in terms of MMP/TIMP expression, and agree with the findings in the only other cell systems in which the PKA and TPA (i.e. PKC) interactions have been studied in this connection (human skin and synovial fibroblasts), in which PKA also repressed PKC-induced MMP-1 (22, 23) and TIMP-1 (22).

In conclusion, the present study provides novel data on MMP-1 and TIMP-1 gene expression and their modulation by the major signal transduction pathways operating in human thyroid cells. Similar and divergent patterns have emerged in the regulation of such gene expression in benign and malignant human thyrocytes, in many instances in accord with the concept of MMP playing the role of stimulating, and TIMP inhibiting, cell invasion. Although MMP-1 may be just one of the many factors responsible for tumor cell invasion, the present findings, demonstrating the possibility (at least in vitro) of repressing MMP gene expression, may have important clinical ramifications.

	Footnotes

 
¹ This work was presented, in part, at the 71st Annual Meeting of The American Thyroid Association, Portland, Oregon, 1998 (Abstract 28). This work was supported by the Israel Cancer Association and the Middle East Cancer Consortium.

Received February 26, 1999.

Revised May 17, 1999.

Accepted June 1, 1999.

	References

Top Abstract Introduction Materials and Methods Results Discussion References

 

1. Salamonsen LA. 1996 Matrix metalloproteinases and their tissue inhibitors in endocrinology. Trends Endocrinol Metab. 7:28–34.
2. Chambers AF, Matrisian LM. 1997 Changing views of the role of matrix metalloproteinases in metastasis. J Natl Cancer Inst. 89:1260–1270.[Abstract/Free Full Text]
3. Gack S, Vallon R, Schaper J, Rüther U, Angel P. 1994 Phenotypic alterations in Fos-transgenic mice correlate with changes in Fos/Jun-dependent collagenase type I expression. J Biol Chem. 269:10363–10369.[Abstract/Free Full Text]
4. Heinrich R, Kraiem Z. 1997 The protein kinase A pathway inhibits c-jun and c-fos protooncogene expression induced by the protein kinase C and tyrosine kinase pathways in cultured human thyroid follicles. J Clin Endocrinol Metab. 82:1839–1844.[Abstract/Free Full Text]
5. Kraiem Z, Sadeh O, Yosef M. 1991 Iodide uptake and organification, tri-iodothyronine secretion, cyclic AMP accumulation and cell proliferation in an optimized system of human thyroid follicles cultured in collagen gel suspended in serum-free medium. J Endocrinol. 131:499–506.[Abstract/Free Full Text]
6. Kraiem Z, Sadeh O, Yosef M, Aharon A. 1995 Mutual antagonistic interactions between the thyrotropin (adenosine 3'-5'-monophosphate) and protein kinase C/epidermal growth factor (tyrosine kinase) pathways in cell proliferation and differentiation of cultured human thyroid follicles. Endocrinology. 136:585–590.[Abstract]
7. Pang X-P, Hershman JM, Chung M, Pekary AE. 1989 Characterization of tumor necrosis factor- receptors in human and rat thyroid cells and regulation of the receptors by thyrotropin. Endocrinology. 125:1783–1788.[Abstract/Free Full Text]
8. Battista S, de Nigris F, Fedele M, et al. 1998 Increase in AP-1 activity is a general event in thyroid cell transformation in vitro and in vivo. Oncogene. 17:377–385.[CrossRef][Medline]
9. Kameyama K. 1996 Expression of MMP-1 in the capsule of thyroid cancer - relationship with invasiveness. Pathol Res Pract. 192:20–26.[Medline]
10. Campo E, Merino MJ, Liotta L, Neumann R, Stetler-Stevenson W. 1992 Distribution of the 72-kd type IV collagenase in nonneoplastic and neoplastic thyroid tissue. Hum Pathol. 23:1395–1401.[CrossRef][Medline]
11. Zedenius J, Stahle-Backdahl M, Enberg U, et al. 1996 Stromal fibroblasts adjacent to invasive thyroid tumors: expression of gelatinase A but not stromelysin 3 mRNA. World J Surg. 20:101–106.[CrossRef][Medline]
12. Demeure MJ, Damsky CH, Elfman F, Goretzki PE, Wong MG, Clark OH. 1992 Invasion by cultured human follicular thyroid cancer correlates with increased ß₁ integrins and production of proteases. World J Surg. 16:770–776.[CrossRef][Medline]
13. Aust G, Hofmann A, Laue S, Rost A, Kohler T, Scherbaum WA. 1997 Human thyroid carcinoma cell lines and normal thyrocytes: expression and regulation of matrix metalloproteinase-1 and tissue matrix metalloproteinase inhibitor-1 messenger-RNA and protein. Thyroid. 7:713–724.[Medline]
14. Eggo MC. 1993 Protein kinase C in the thyroid. J Endocrinol. 138:1–5.[Abstract/Free Full Text]
15. Crawford HC, Matrisian LM. 1996 Mechanisms controlling the transcription of matrix metalloproteinase genes in normal and neoplastic cells. Enzyme Protein. 49:20–37.[Medline]
16. Chiu R, Angel P, Karin M. 1989 Jun B differs in its biological properties from, and is a negative regulator of, c-Jun. Cell. 59:979–986.[CrossRef][Medline]
17. Mauviel A, Chung K-Y, Agarwal A, Tamai K, Uitto J. 1996 Cell-specific induction of distinct oncogenes of the Jun family is responsible for differential regulation of collagenase gene expression by transforming growth factor-ß in fibroblasts and keratinocytes. J Biol Chem. 271:10917–10923.[Abstract/Free Full Text]
18. Karin M, Liu Z, Zandi E. 1997 AP-1 function and regulation. Curr Opin Cell Biol. 9:240–246.[CrossRef][Medline]
19. Hölting T, Siperstein AE, Clark OK, Duh Q-Y. 1995 Epidermal growth factor (EGF) - and transforming growth factor alpha-stimulated invasion and growth of follicular thyroid cancer cells can be blocked by antagonism to the EGF receptor and tyrosine kinase in vitro. Eur J Endocrinol. 132:229–235.[Abstract/Free Full Text]
20. Hoelting T, Tezelman S, Siperstein AE, Duh Q-Y, Clark OH. 1993 Thyrotropin stimulates invasion and growth of follicular thyroid cancer cells via PKC - rather than PKA-activation. Biochem Biophys Res Commun. 195:1230–1236.[CrossRef][Medline]
21. Laurent E, Mockel J, Van Sande J, Graff I, Dumont JE. 1987 Dual activation by thyrotropin of phospholipase C and cyclic AMP cascades in human thyroid. Mol Cell Endocrinol. 52:273–278.[CrossRef][Medline]
22. DiBattista JA, Pelletier JP, Zafarullah M, Fujimoto N, Obata K, Martel-Pelletier J. 1995 Coordinate regulation of matrix metalloproteases and tissue inhibitor of metalloproteinase expression in human synovial fibroblasts. J Rheumatol. [Suppl 43]22 :123–128.
23. Salvatori R, Guidon Jr PT, Rapuano BE, Bockman RS. 1992 Prostaglandin E₁ inhibits collagenase gene expression in rabbit synoviocytes and human fibroblasts. Endocrinology. 131:21–28.[Abstract/Free Full Text]

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This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Korem, S. Articles by Kraiem, Z. Search for Related Content PubMed PubMed Citation Articles by Korem, S. Articles by Kraiem, Z.