Activation of pro-MMP-2 mediated by MT1-MMP in human salivary gland carcinomas: possible regulation of pro-MMP-2 activation by TIMP-2

Matrix metalloproteinases (MMPs), a family of extracellular matrix-degrading enzymes, are considered to play important roles in cancer invasion and metastasis. The present study examined the production levels of eight different MMPs (MMP-1, 2, 3, 7, 8, 9 and 13, and MT1-MMP) and two tissue inhibitors of metalloproteinases (TIMP-1 and 2) in homogenates of human salivary gland carcinomas [mucoepidermoid carcinomas (MECs), adenoid cystic carcinomas (ACCs), and adenocarcinomas (ADEs)] and non-neoplastic control salivary glands using sandwich enzyme immunoassay systems. The levels of MMP-1, MMP-2, MMP-13, MT1-MMP, and TIMP-1 were significantly higher in the carcinoma samples than in the controls (p < 0.05). Gelatin zymography demonstrated that the activation ratio of the MMP-2 zymogen (pro-MMP-2) was significantly higher in the carcinomas than in the controls (p < 0.05). In addition, the activation ratio in MECs was significantly higher than that in ACCs or ADEs (p < 0.01) and also correlated with histological grade and lymph node metastasis in MECs (p < 0.05), whereas the ratio showed no such correlation in ACCs or ADEs. Although the production levels of pro-MMP-2 and MT1-MMP were similar among these carcinoma groups, TIMP-2 levels were significantly higher in ACCs and ADEs than in MECs (p < 0.01). In carcinoma samples, the pro-MMP-2 activation ratio correlated directly with the MT1-MMP/TIMP-2 ratio (r = 0.736, n = 23; p < 0.01). Immunohistochemistry and in situ zymography demonstrated localization of MMP-2, MT1-MMP, and TIMP-2 to carcinoma cells, but only in MECs did carcinoma cell nests exhibit gelatinolytic activity, which was inhibited by 1,10-phenanthroline. These results suggest that enhanced activation of pro-MMP-2 mediated by MT1-MMP is implicated in the invasion and metastasis of MECs and that TIMP-2 may regulate pro-MMP-2 activation in salivary gland carcinomas.     

Selective progesterone receptor modulator asoprisnil down-regulates collagen synthesis in cultured human uterine leiomyoma cells through up-regulating extracellular matrix metalloproteinase inducer

BACKGROUND: A recent clinical trial demonstrated that selective progesterone receptor modulator asoprisnil is effective in reducing uterine leiomyoma volume. We investigated the effects of asoprisnil in vitro on the expression of the extracellular matrix (ECM)-remodeling enzymes and collagens in cultured leiomyoma and matching normal myometrial cells. METHODS: The expression of extracellular matrix metalloproteinase inducer (EMMPRIN), matrix metalloproteinases (MMPs), tissue inhibitors of MMP (TIMPs) and collagens were assessed by western blot analysis. RESULTS: Untreated cultured leiomyoma cells had significantly lower EMMPRIN (P < 0.05), MMP-1 (P < 0.05) and membrane type 1-MMP (MT1-MMP) (P < 0.01) protein contents, but significantly higher TIMP-1 (P < 0.05), TIMP-2 (P < 0.01), type I (P < 0.05) and type III (P < 0.01) collagen protein contents compared with untreated cultured myometrial cells. Treatment with asoprisnil at concentrations > or =10(-7) M for 48 h significantly (P < 0.05) increased EMMPRIN, MMP-1 and MT1-MMP protein contents, and decreased TIMP-1 (P < 0.05), TIMP-2 (P < 0.01), type I (P < 0.01) and type III (P < 0.05 at 10(-7) M; P < 0.01 at 10(-6) M) collagen protein contents in cultured leiomyoma cells compared with control cultures. However, asoprisnil treatment did not affect the protein contents of ECM-remodeling enzymes and collagens in cultured myometrial cells. CONCLUSIONS: These results suggest that asoprisnil may reduce collagen deposit in the ECM of cultured leiomyoma cells through decreasing collagen synthesis and enhancing the expression of EMMPRIN, MMPs and TIMPs without comparable effects on cultured myometrial cells.     

Protein kinase C activation by phorbol ester increases in vitro invasion through regulation of matrix metalloproteinases/tissue inhibitors of metalloproteinases system in D54 human glioblastoma cells

To elucidate possible mechanisms of phorbol 12-myristate 13-acetate (PMA) induced in vitro invasiveness of glioblastoma cells, we examined expression levels of membrane-type 1 matrix metalloproteinase (MT1-MMP), MMP-2, MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 using Western blotting and gelatin zymography assay, and found that PMA induced the secretion of MMP-9, activated MMP-2 proenzyme to fully active form of 59 kDa, down-regulated the TIMP-1 and TIMP-2 secretion, and increased MT1-MMP on the cell surface. However, PKC inhibitor Go 6983 reversed all of these effects brought about by PMA. We, therefore, conclude the activation of PKC by PMA in these cells plays a critical role in the regulation of MMPs/TIMPs system, which has a major role in tumor invasion and metastasis.     

Coexpression of cyclooxygenase-2 and matrix metalloproteinases in human aortic atherosclerotic lesions

Inflammation appears to have a major role in the development of atherosclerosis. Cyclooxygenase-2 (COX-2) is involved in the inflammatory response via the generation of prostanoids that, in turn, are involved in the production of matrix metalloproteinases (MMPs). This study aimed to investigate atherosclerosis in human aortas for in situ tissue distribution of COX-2, MMPs including MMP-9 and membrane type 1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinase-2 (TIMP-2). Immunohistochemical studies were performed on atherosclerotic lesions of aortas from patients with aortic aneurysms (n = 4) and dissections (n = 3) by using antibodies to COX-2, MMP-9, MT1-MMP, and TIMP-2. Control tissues were obtained from traumatically dissected aortas (n = 2). All specimens from diseased aortas had atherosclerotic lesions ranging from fatty streak to atheromatous plaques. In control, there was no expression of COX-2, MMP-9, and MT1-MMP in all aortic layers. Immunoreactivity for COX-2 was predominantly noted in macrophages and smooth muscle cells (SMCs) of the intima including atherosclerotic plaque itself and the medial layer of the plaque base, as well as in SMCs and endothelial lining of the vasa vasorum in the adventitia. Immunoreactivity for MMP-9 and MT1-MMP was found in the same distribution as that of COX-2. Additionally, the expression of TIMP-2 increased in relation to MMP-9 expression. This study demonstrates that COX-2 is coexpressed with MMP-9 and MT1-MMP, not only by macrophages and SMCs in atherosclerotic lesions, but also in endothelial lining of the vasa vasorum of human aortas. Thus, vascular inflammatory reactions may influence extracellular matrix remodeling by coactivation of MMPs in the development of atherosclerosis and, in turn, the progression of disease.     

Regulation of matrix metalloproteinases and their inhibitors in the left ventricular myocardium of patients with aortic stenosis

Aortic stenosis (AS) results in myocyte and extracellular matrix remodeling in the human left ventricle (LV). The myocardial renin-angiotensin system is activated and collagens I and III and fibronectin accumulate. We determined the yet unknown regulation of enzymes that control collagen turnover, i.e., LV matrix metalloproteinases (MMP) and their tissue inhibitors (TIMPs) in human AS. We compared LV samples from AS patients undergoing elective aortic valve replacement (n=19) with nonused donor hearts with normal LV function (controls, n=12). MMP-2, MMP-9, MT1-MMP, and extracellular matrix metalloproteinase inducer (EMMPRIN), TIMP-1, TIMP-2, TIMP-3, and TIMP-4 mRNA were quantitated by real-time RCR. MMP-1, MMP-2, MMP-3, TIMP-3, TIMP-4, and EMMPRIN protein were measured by immunoblotting and MMP-9 and TIMP-1 protein by ELISA. Gelatinolytic MMP-2 and MMP-9 activity was measured by zymography. MMP-2 was increased in AS at mRNA, protein, and activity levels (131%, 193%, and 138% of controls). MMP-3 protein (308%) and EMMPRIN mRNA and protein were also upregulated (171% and 200%). In contrast, MMP-1 (37%) and MMP-9 mRNA, protein, and activity (26%, 21%, and 52%) were downregulated. MMP-9 activity was inversely correlated with LV size. TIMP-1 mRNA and protein were decreased (55% and 73%). In contrast, TIMP-2 mRNA (358%), TIMP-3 mRNA and protein (145% and 249%) were increased. TIMP-4 mRNA was not altered, but TIMP-4 protein was upregulated to 350%. Changes were similar in AS patients with normal and impaired LV ejection fraction. The dysregulation of myocardial MMPs and TIMPs in human AS starts at an early disease stage when LV function is still normal. In spite of upregulation of some MMPs the balance between MMP and TIMP is shifted towards MMP inhibition in human AS and may contribute to collagen accumulation.     

Cell membrane-associated MT1-MMP-dependent activation of pro-MMP-2 in A375 melanoma cells.

Matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, can degrade extracellular matrix components under physiological conditions and during cancer invasion and metastasis. Among the MMPs, the 72 kDa type IV collagenase MMP-2 (gelatinase A) is activated in a membrane-associated manner by an activation complex composed of membrane type 1 matrix metalloproteinase (MT1-MMP), tissue inhibitor of matrixmetalloproteinase-2 (TIMP-2), and pro-MMP-2 in the presence of alphavbeta3 integrin receptor. The activation of pro-MMP-2 correlates with increased occurrence of metastases. Increased MMP-2 activity has been demonstrated in many human tumors. In the present communication, we studied cell surface-associated activation of MMP-2 (72 kDa collagenase type IV) in the moderately metastatic human melanoma cell line A375. RESULTS: Activation of purified 72 kDa collagenase type IV, pro-MMP-2 from cervical cancer tissue homogenate and from serum-free culture medium of HT1080 cells grown in presence of concanavalin A, by A375 cells, was shown by gelatin zymography. A375 cells activated only pro-MMP-2 from purified MMP-9/MMP-2 mixture indicating that the activation is specific for MMP-2. Activation of MMP-2 and purified collagenase type IV by A375 membrane fraction and membrane extract was also demonstrated by gelatin zymography. When A375 cells were first incubated with anti-MT1-MMP polyclonal antibody, activation of collagenase type IV was significantly decreased, indicating that membrane-associated MMP-2 activation is MT1-MMP-mediated. Immunocytochemistry showed MT1-MMP localization at focal adhesion sites. The presence of the components of activation complex-MT1-MMP and integrin alphavbeta3-were confirmed by Western blot, cell adhesion assay, and integrin subunit assay. CONCLUSION: Our experimental findings furnish another example of the unique membrane-associated MMP-2 activation mechanism in A375 melanoma cells and clearly indicate the role of MT1-MMP in MMP-2 activation. The information could help in developing new therapies designed to interfere with MMP activation and management of cancer and metastases.     

Differential expression patterns of MMPs and their role in the invasion of epithelial premalignant tumors and invasive cutaneous squamous cell carcinoma

Co-expression of several members of the matrix metalloproteinase (MMP) family is characteristic of human malignant tumors. MMP-2, MMP-9, TIMP-2, and MT1-MMP are thought to be involved in the process of destruction of basement membranes and stromal invasion by neoplastic epithelial cells. In this study, we investigated the expression and role of MMPs in cutaneous oncogenesis. Tissue microarray consisting of 62 squamous cell carcinomas (SCC), 32 Bowen's disease (BD) samples, 25 normal epidermis samples were obtained for the study. MMP-2,-9, MT1-MMP and TIMP-2 proteins were examined by immunohistochemical staining and mRNA level was detected by quantitative RT-PCR in fresh tissues consisting of 5 cutaneous SCCs and paired normal epidermis samples. Gelatinase activity of MMP-2 and MMP-9 was investigated by gelatin zymography and protein levels of MT1-MMP and TIMP-2 were measured by western blot in 2 human SCC cell lines. The invasive property was evaluated with invasion assays using Transwell filters. SCC exhibited significantly increased MMP-2, MT1-MMP and decreased TIMP-2 mRNA and protein expression compared to that of the normal epithelium. Immunohistochemical staining revealed that MT1-MMP was strongly expressed on the invasive front of SCCs, whereas BD exhibited higher expression around the dyskeratotic cells in the epithelium. In comparison with the expression observed in BD, SCC exhibited significantly increased MMP-2 expression. In addition, high MMP-2 and MT1-MMP expression and low TIMP-2 expression had a significant positive correlation with the invasiveness of SCC cell lines in vitro. Our results revealed significantly increased MT1-MMP and MMP-2 expression and decreased TIMP-2 expression in cutaneous SCC, and the expression correlated with the invasiveness of SCC cell lines. Therefore, the expression of these factors in cutaneous tumors may serve as an indicator of tumor aggressiveness and invasion.     

Gelatin zymography and substrate cleavage assays of matrix metalloproteinase-2 in breast carcinoma cells overexpressing membrane type-1 matrix metalloproteinase

Gelatin zymography is the common method for examining matrix metalloproteinase-2 (MMP-2) in cells and media samples. Activation of the latent MMP-2 zymogen involves its binding to the cell surface MT1-MMP*TIMP-2 (membrane type-1 matrix metalloproteinase/tissue inhibitor of matrix metalloproteinase-2) complex with subsequent cleavage of proMMP-2 by TIMP-2-free adjacent MT1-MMP. This is followed by autolytic maturation of the activation intermediate and the release of the mature MMP-2 species from cell surfaces into the extracellular milieu. To observe the MMP-2 activation pathway in more detail, proMMP-2-deficient MCF7 breast carcinoma cells expressing MT1-MMP were incubated with excess proMMP-2 to saturate the available MT1-MMP*TIMP-2 surface receptors. After removal of the unbound material, the kinetics of proMMP-2 activation and MMP-2 release from cells into media was monitored by gelatin zymography and substrate cleavage. Our observations demonstrate that gelatin zymography is insufficient for providing meaningful information about the status of MMP-2. The proteolytically competent mature MMP-2 moiety alone, but not in its complex with TIMP-2, was released from the cells. In tissue culture conditions, the enzyme's proteolytic activity was suppressed in the next 30 to 60 minutes by tissue inhibitors of MMPs, especially by TIMP-1. The picture emerges that there is a likely temporal regulation of MMP-2 activity by TIMPs in tumor cells. These relatively rapid changes of the MMP-2 status cannot be detected by gelatin zymography. Additional studies are needed to examine the significance of this phenomenon in vivo.     

(-)Epigallocatechin-3-gallate directly inhibits MT1-MMP activity,leading to accumulation of nonactivated MMP-2 at the cell surface

Consumption of green tea has been associated with prevention of cancer development, metastasis, and angiogenesis. Given the crucial role of the matrix metallo-proteinase-2 (MMP-2) on the degradation of the extracellular matrix instrumental to invasion, we examined the effect of the main flavanol present, (-)epigallocatechin-3-gallate (EGCG), on membrane-type 1 MMP (MT1-MMP), the receptor/activator of MMP-2. In-solution fluorimetric assay with activated MT1-MMP and gelatin-zymography with MT1-MMP catalytic domain alone and pro-MMP-2 activation by the same domain revealed dose-dependent inhibition of MT1-MMP at EGCG concentrations slightly lower than that reported to inhibit MMP-2 and MMP-9. Cytofluorimetry and immunolocalization revealed that EGCG does not impair MT1-MMP/TIMP-2/MMP-2 presence on the cell membrane. In the membrane extract of HT-1080 human fibrosarcoma cells, 10 micro M EGCG caused a strong increase in MT1-MMP level and accumulation of pro-MMP-2 while leaving activated MMP-2 unchanged. EGCG thus exerts inhibition of MT1-MMP, which restrains activation of MMP-2; this may confer the antiangiogenic and antimetastatic activity associated with green tea.     

Induction of membrane-type matrix metalloproteinase 1 (MT1-MMP) expression in human fibroblasts by breast adenocarcinoma cells

Membrane-type matrix metalloproteinase 1 (MT1-MMP) has been recently described as an activator of proMMP-2 (MMP-2) which is involved in tumor invasion. We have shown by in situ hybridization that MT1-MMP is produced by stromal cells in close contact to preinvasive and invasive tumor cells of breast carcinomas. Of particular interest was the observation that some fibroblasts express this enzyme in focal areas in preinvasive lesions, suggesting that particular tumor cells may stimulate fibroblasts to produce MT1-MMP. We have therefore compared the ability of two different breast cancer cell lines, one non-invasive (MCF7) and one invasive (MDA-MB-231) to stimulate MT1-MMP production in human fibroblasts with consequent proMMP-2-activation. The MDA-MB-231 conditioned medium induced MT1-MMP mRNAs in human fibroblasts and a parallel activation of proMMP-2 whereas MCF7 conditioned medium did not have any effect. These results suggest the existence of soluble factor(s) secreted by invasive or some preinvasive breast tumor cells which stimulate fibroblasts to produce and activate MMPs, and emphasize the cooperation between cancer and stromal cells in tumor invasion.     

38Dimerization of endogenous MT1-MMP is a regulatory step in the activation of the 72 kDa gelatinase, MMP-2, on fibroblasts and fibrosarcoma cells

Matrix metalloproteases (MMPs) are centrally engaged in the processes of extracellular matrix turnover that occur during cancer invasion. An important MMP cascade reaction is initiated by the membrane-anchored matrix metalloprotease, MT1-MMP, which serves to activate the proenzyme form of the secreted gelatinase, matrix metalloprotease-2 (MMP-2). This reaction occurs in an interplay with the matrix metalloprotease inhibitor, TIMP-2, and the proposed mechanism involves two molecules of MT1-MMP in complex with one TIMP-2 molecule. To study this, as well as other roles of MT1-MMP, we have now raised a panel of monoclonal antibodies against the protein. These antibodies have been raised in MT1-MMP knock-out mice and react against conserved epitopes in murine and human MT1-MMP. Using one of these antibodies we provide positive evidence that proMMP-2 activation is governed by dimerization of MT1-MMP on the surface of fibroblasts and fibrosarcoma cells. The antibody in question binds specifically to MT1-MMP on the cell surface, as shown by immunofluorescence experiments. It is directed against the hemopexin domain of MT1-MMP and has no effect on the catalytic activity of the protease domain. The antibody induces dimerization of the endogenous MT1-MMP on the cell surface. Through this reaction, it markedly stimulates the formation of the 62 kDa active MMP-2 and the processing into a 59 kDa product that retains gelatinolytic activity. This effect is indeed a consequence of MT1-MMP dimerization because it requires the divalent monoclonal antibody with no effect being obtained with monovalent Fab fragments. Since only a negligible level of proMMP-2 activation is obtained with MT1-MMP expressing cells in the absence of dimerization, our results identify the dimerization event as a critical level of proteolytic cascade regulation.     

Reduced expression of tissue inhibitor of metalloproteinase in nodal metastasis of stomach cancer.

The matrix metalloproteinases (MMPs) have been associated with tumor cell invasion and metastasis of human cancers by mediating the degradation of extracellular matrix components. Therefore, these enzymes and their inhibitor (TIMP-2) constitute promising targets in the development of anticancer therapies. In order to investigate the correlation between expressions of TIMP-2, MMPs and clinical outcome, immunohistochemical staining of MMP-2, MMP-9, and TIMP-2 were performed on paraffin-embedded tissue sections of 15 early gastric cancers (EGC) and 15 advanced gastric carcinomas (AGC) without nodal metastasis and 15 AGC with nodal metastasis (AGCn+). MMP-2 and MMP-9 were expressed in neoplastic cell plasma membrane in 83.3% and 88% of cases of AGC, respectively with inter-tumoral variability of staining intensity. MMP-2 and MMP-9 staining were not correlated with presence of nodal metastasis or degree of invasion depth at the time of diagnosis (p>0.05). The immunoreactivity of TIMP-2 was detected in the peri-tumoral stroma. Residual benign stomach tissue showed no or weak immunoreactivity for TIMP-2 staining. Among AGC, neoplasms with diffuse and strong TIMP-2 staining have less frequent metastasis (28.6%) than cases with focal and weak (68.8%) (p<0.05). Early gastric cancer revealed diffuse and strong TIMP-2 expressions. We conclude that clinical outcome such as depth of invasion or metastasis is more closely related to the expression of TIMP-2 than the corresponding MMPs.     

The metalloproteinase inhibitor TIMP-2 is down-regulated by androgens in LNCaP prostate carcinoma cells

Tissue inhibitors of metalloproteinases (TIMPs) have been shown to perform several biological functions in tumor promotion, principally by their action of inhibiting matrix metalloproteinases (MMPs) at different steps of the metastatic process. In particular, TIMP-2 is involved in a functional complex with the membrane-type 1 (MT1) MMP to convert the secreted MMP-2 progelatinase into the fully active proteolytic enzyme. We used the human, androgen-sensitive prostate carcinoma cell line LNCaP in coculture with the human osteosarcoma cell line OHS to experimentally address the possibility of androgen-dependent regulatory effects on the functional MT1-MMP/TIMP-2/MMP-2 complex upon interaction between prostate carcinoma and osteoblastic cells in metastasis of prostate cancer to bone. In the LNCaP cells a gradual, time-dependent decline in TIMP-2 mRNA expression was observed in the presence of the synthetic androgen analogue R1881 (100 nM), reaching ∼25% of the control level after 48 h of incubation. Consistent with this, the accumulation of secreted TIMP-2 in media from R1881-treated cells was significantly inhibited already after 3 h. Neither MMP-2 gelatinolytic activity nor expression of MT1-MMP was detected in LNCaP cells. In contrast, the OHS cells showed membrane-associated MT1-MMP expression as well as MMP-2 secretion. However, R1881 treatment of the LNCaP/OHS coculture model did not seem to change the overall proteolytic activity of the MT1-MMP/TIMP-2/MMP-2 complex. Hormonal control of TIMP-2 expression in prostate carcinoma cells has not been previously reported, but whether such regulation has any functional role in the development of osteoblastic metastases in prostate cancer is still unclear. This revised version was published online in July 2006 with corrections to the Cover Date.     

基质金属蛋白酶及其组织抑制因子在人前列腺组织及各种类型前列腺细胞中的表达

目的：研究基质金属蛋白酶（MMPs）及其组织抑制因子（TIMPs）在人前列腺组织及各种类型细胞中的表达。方法： 用半定量RT－PCR的方法，对癌变和非癌变部分的前列腺组织、原代培养的平滑肌细胞、成纤维细胞、上皮细胞以及4种前列腺上皮细胞系（BPH－1、LNCaP、DU－145和PC－3）中MMP2、MMP7和MMP9、膜型基质金属蛋白酶1和3（MT1－MMP和MT3－MMP）及其组织抑制因子1和2（TIMP－1和TIMP－2）的mRNA 水平进行了测定。结果：MMP-2主要在前列腺基质细胞中表达；MMP-7和MMP-9则在前列腺上皮细胞中有较高的表达；MT1-MMP、MT3-MMP、TIMP-1和TIMP-2在前列腺基质细胞和上皮细胞中均有表达，但MT1-MMP和MT3-MMP在成纤维细胞中的表达量较高；另外，各种基质金属蛋白酶及其组织抑制因子在各种前列腺细胞系中也存在差异表达。结论： MMPs和TIMPs在前列腺组织及其各种类型细胞中的差异表达提示：它们可能在前列腺癌的转移中起着不同的作用。     

胸腺上皮肿瘤组织中基质金属蛋白酶-2活性与Ⅰ型膜型基质金属蛋白酶 mRNA表达的相关性

目的探讨胸腺瘤和胸腺癌中基质金属蛋白酶（MMP）-2、Ⅰ型膜型（MT1）-MMP、金属蛋白酶组织抑制剂（TIMP）-2mRNA的表达和MMP-2蛋白活性的关系。方法分别用real-time逆转录．聚合酶链反应（RT-PCR,Taqman法）、明胶酶谱法和Filmin situ gelatin-Zymography（FIZ）对正常的胸腺组织（2例）、胸腺瘤（12例）和胸腺癌（2例）患者的新鲜肿瘤组织中MMP-2、MT1-MMP、TIMP-2mRNA的表达,pro-MMP-2的活性率及活性蛋白的定位进行测定。结果MMP-2、MT1-MMP及TIMP-2mRNA在Ⅰ期与Ⅱ期和Ⅲ期与Ⅳ期中的表达差异均无统计学意义（P〉0．05）,在Ⅰ～Ⅱ期与Ⅲ～Ⅳ期和胸腺癌3组中差异均有统计学意义（P〈0．01）。在AB、B1型（混合型和淋巴细胞为主型）与B2、B3型（皮质型和多角细胞为主型）以及胸腺癌3组中差异均有统计学意义（P〈0．05）。MMP-2的蛋白活性率（MMP-2／pro—MMP-2＋MMP-2）在Ⅰ～Ⅱ期、Ⅲ～Ⅳ期和胸腺癌各组中差异有统计学意义（P〈0．05）,在AB、B1型与B2、B3型以及胸腺癌各组中的差异均具有统计学意义（P〈0．05）。胸腺瘤各期及各型中MT1-MMP、TIMP-2mRNA与MMP-2蛋白活性表达均呈正相关,且相关程度相似（r=0．7235、r=0．7647、P〈0．005）。MMP-9的蛋白表达在各组间差异均无统计学意义。结论MMP-2、MT1-MMP及TIMP-2的mRNA表达与胸腺瘤临床分期、病理分型相关,MMP-2的活性与MT1-MMP和TIMP-2的表达升高正相关。推测MT1-MMP通过TIMP-2对MMP-2的激活起促进作用。     

Promoted activation of matrix metalloproteinase (MMP)-2 in keloid fibroblasts and increased expression of MMP-2 in collagen bundle regions: implications for mechanisms of keloid progression

Aims:  Keloid is characterized by excessive deposition of collagen, resulting from aberrant extracellular matrix (ECM) production and degradation. The aim was to investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in pathological wound healing in keloids.
Methods and results:  Semiquantitative analysis of 60 keloid tissue samples and 25 mature scar tissue samples demonstrated significantly increased expression of MMP-2, TIMP-2 and TIMP-3 in keloids compared with mature scars. Within keloid regions, MMP-2 expression was significantly higher in collagen bundle regions than in non-collagen bundle regions. Double immunofluorescence revealed that keloid fibroblasts between collagen bundles exhibited MMP-2, TIMP-2 and membrane-type 1 MMP (MT1-MMP) co-expression, whereas only MMP-2 expression was evident on the edge of collagen bundles. Western blot analysis and gelatin zymography of 13 keloid-derived fibroblasts (KFbs) and six normal skin dermal-derived fibroblasts (NFbs) demonstrated that unstimulated KFbs exhibited significantly increased MMP-2 activity and expression compared with NFbs under the same conditions.
Conclusions:  These results together indicate that MMP-2 activity can be promoted in keloid fibroblasts between collagen bundles in cooperation with TIMP-2 and MT1-MMP. This could contribute to remodelling of collagen bundle regions and invasion of fibroblasts into peripheral normal regions through promoted degradation of ECM.     

Expression of matrix metalloproteinases 2 and 7 in tumor cells correlates with the World Health Organization classification subtype and clinical stage of thymic epithelial tumors

To investigate the roles of matrix metalloproteinases (MMPs) in thymic epithelial tumors, we examined the expression of MMP-2, -7, and -9; membrane-type 1 (MT1)-MMP; and tissue inhibitor of metalloproteinase-2 (TIMP-2) in 57 tumors by immunohistochemistry and in selected 15 cases by in situ hybridization. The tumors consisted of 5 type A, 12 type AB, 11 type B1, 11 type B2, 9 type B3, and 9 type C thymomas according to the World Health Organization histologic classification system and of 22 stage I, 13 stage II, 8 stage III, and 14 stage IV thymomas according to the Masaoka staging system. In the positive cases, MMPs and TIMP-2 were expressed in both tumor cells and stromal cells. The cellular localization of MMPs detected by immunohistochemistry was almost identical with that of the mRNA signals detected by in situ hybridization. MMP-2 and MMP-7 were predominantly expressed in type B3 thymoma and type C thymoma, respectively. Expression of MT1-MMP and TIMP-2 correlated with that of MMP-2, indicating a proteolytic activation of the latter. MMP-9 was prominent in type B2 thymoma. Expression in tumor cells of MMP-2 or MMP-7 was also correlated with clinical stage. The present study suggests that certain MMPs may play an important role in the tumor progression of different subtypes of thymic epithelial tumors and that MMP-2 and MMP-7 may contribute to the tumor aggressiveness and malignant potential.