TNF-alpha increases human melanoma cell invasion and migration in vitro: the role of proteolytic enzymes

Inflammatory mediators have been reported to promote malignant cell growth, invasion and metastatic potential. More specifically, we have recently reported that tumour necrosis factor alpha (TNF-alpha) increases melanoma cell attachment to extracellular matrix (ECM) substrates and invasion through fibronectin. In this study, we extend these investigations asking specifically whether the TNF-alpha effect on cell invasion and migration involves activation of proteolytic enzymes. We examined the effect of TNF-alpha on melanoma expression/activation of type IV gelatinases matrix metalloproteinases 2 and 9 (MMPs -2 and -9) and general proteolytic enzymes. Stimulation with TNF-alpha significantly increased both melanoma cell migration at 24 h (+21%) and invasion through fibronectin (+35%) but did not upregulate/activate the expression of latent MMP-2 constitutively produced by these cells and did not upregulate their general protease activity. However, the increased cell migration and invasion through fibronectin observed following stimulation with TNF-alpha were inhibited by the general protease inhibitor alpha(2) macroglobulin. These findings suggest that the promigratory and proinvasive effect of TNF-alpha on this melanoma cell line may be mediated to some extent by induction of localised cell membrane-bound degradative enzyme activity, which is not readily detected in biochemical assays.     

Inhibition of proteolytic enzymes in the in vitro amnion model for basement membrane invasion

The ability of B16-F10 mouse melanoma cells to cross an amnion basement membrane was determined in the presence of strong inhibitors of both serine and cysteine proteases. The concentrations of inhibitors were at orders of magnitude higher than their Ki values to serine and cysteine proteases implicated in metastasis, thus ensuring a complete inhibition for tumor secreted proteases such as cathepsin B-like proteases, plasminogen activators, and plasmin. Under these conditions of high serine and cysteine protease inhibitor concentrations, no significant decrease in B16-F10 melanoma cell invasion through the amnion was observed. Separate experiments showed that the inhibitors were neither toxic to the cells nor degraded. The results show that neither tumor cell secreted cathepsin B-like proteases nor plasminogen activator have a controlling role in basement membrane crossing in this metastatic model. A possible role for tumor cell membrane proteases in basement membrane invasion, in which the substrates of the protease bind to receptor sites near a membrane associated proteolytic activity, is not eliminated.     

Brain surface invasion and metastasis of murine malignant melanoma variants

Mouse B16 melanoma sublines were selected sequentially for their abilities to colonize brain meninges and leptomeninges of C5713L/6 mice. After 14 selections subline 1316-B14b was established that formed significantly more brain tumor colonies than the parental B16 line. Examination of brains at various times after intravenous or intra-arterial injection of B16 cells by electron microscopy revealed that B14b melanoma cells lodged in small brain blood vessels, proliferated and invaded through vessel walls into brain parenchyma and also along small blood vessels at perivascular sites. Invasion into brain parenchyma was characterized by extension of melanoma cell filopodia resulting in fragmentation and sometimes enfulgment of glial and neural cells.Analysis of cell surface proteins of B16 melanoma sublines revealed increased exposure of a M_r 90 000 glycoprotein on the high brain-colonizing cells. Antibodies against the M_r 90 000 glycoprotein reacted with a variety of human melanoma cell lines and with some fetal and adult tissues, indicating that this melanoma-associated component is not species-, tumor- or tissue-specific. The glycoprotein could be a cell surface receptor important in the survival and growth properties of melanoma cells in brain microenvironments.     

Functional role of melanoma inhibitory activity in regulating invasion and metastasis of malignant melanoma cells in vivo

MIA (melanoma inhibitory activity) has been previously isolated from the tissue culture supernatant of melanoma cell lines as an autoregulatory activity, inhibiting thymidine incorporation. However, subsequent analyses of melanocytic tumours in vivo have correlated enhanced MIA expression with progression of melanocytic tumours, conflicting with the idea that MIA acts as a tumour suppressor. To investigate the role of MIA in vivo, we have therefore generated a panel of stably transfected B16 cell clones secreting different amounts of MIA. The capacity of these cell clones to form lung metastases in syngeneic C57Bl6 mice was strictly correlated to the level of MIA secretion, but the clones did not differ with respect to their proliferation in vitro. In summary, we suggest that MIA plays a causal role in promoting the metastasis of malignant melanomas, involving inhibition of tumour cell attachment to extracellular matrix molecules within their local milieu.     

Selective inhibition of proteolytic enzymes in an in vivo mouse model for experimental metastasis

Peptide aldehyde transition state analogue inhibitors of serine and cysteine proteases have been used to selectively inhibit proteases for which prior evidence supports a role in tumor cell metastasis. These enzymes include cathepsin B, urokinase plasminogen activator (PA), and thrombin. The inhibition constants of the peptidyl aldehyde inhibitors show that they are highly selective for a particular targeted serine or cysteine protease. The inhibitors are introduced by i.p. injection or by miniosmotic pumps into syngeneic C57BL/6 mice also given injections of B16-F10 melanoma cells, and the number of metastatic foci in the lung was determined. While the injection protocol gave an initially high but changing in vivo concentration of inhibitor over time, the minipump implant gave a constant steady state concentration of inhibitor over 5-7 days. Minipump infusion of leupeptin (acetylleucylleucylargininal), a strong inhibitor of cathepsin B at a steady state plasma concentration 1000-fold greater than its Ki(cathepsin B), gave no significant decrease in lung colonization by the B16 tumor cells. Ep475, a stoichiometric irreversible peptide inhibitor of cathepsin B-like proteases, also did not significantly inhibit metastatic foci formation. Introduction of selective inhibitors of urokinase PA, tert-butyloxycarbonylglutamylglycyl-argininal and H-glutamylglycylargininal at concentrations near its Ki, produced no significant decrease in mouse lung colonization. The selective thrombin inhibitor D-phenylalanylprolylargininal infused to a steady state concentration 100-fold greater than its Ki dramatically increased B16 melanoma colonization of mouse lung. The results indicate that neither secreted cathepsin B-like nor urokinase PA have roles in B16 colonization of mouse lung, while thrombin may have a role in preventing metastasis. These experiments do not eliminate roles for a cathepsin B-like enzyme or urokinase PA in the initial steps of the metastatic process.     

Retinoic acid inhibition of human melanoma cell invasion through a reconstituted basement membrane and its relation to decreases in the expression of proteolytic enzymes and motility factor receptor

Treatment of four A375 human melanoma sublines (A375, A375P, A375P-5, A375M), exhibiting distinct metastatic potentials in vivo, with beta-all-trans-retinoic acid in vitro caused a dose- and time-dependent inhibition of the ability of these cells to penetrate Matrigel-coated filters using a reconstituted basement membrane invasion assay. The possible mechanisms of action responsible for the antiinvasive effect were further investigated, and the data showed that compared with untreated cells the retinoic acid-treated cells: (a) secreted lower levels of collagenolytic enzymes, as demonstrated by a decreased ability of the cells to degrade [3H]proline-labeled type IV collagen substrate and by a reduction in the activity of a secreted Mr 64,000 collagenolytic enzyme detected in type IV collagen-containing polyacrylamide gels; (b) expressed lower levels of the human type IV collagenase mRNA (except in the A375P cells), as detected by Northern blot analysis; (c) exhibited decreased levels of tissue plasminogen activator activity, as demonstrated by a chromogenic assay; (d) were 10-40% less adhesive to a reconstituted basement membrane matrix, as determined by a 60-min Na2(51)CrO4-labeled cell attachment assay; (e) exhibited an increase in the high affinity metastasis-associated cell surface laminin receptor, as determined by flow cytometry after binding of fluorescently labeled laminin receptor antibody; and (f) expressed decreased amounts of gp78, a cell surface receptor for motility factor, demonstrated by immunoblotting and immunofluorescence. Collectively, these data suggest that retinoic acid inhibits tumor cell invasion through a basement membrane-like matrix by suppressing matrix degradation and by altering cell surface receptors.     

长链非编码RNA在恶性黑色素瘤侵袭和转移中作用的研究进展

恶性黑色素瘤(malignant melanoma)是恶性程度极高的皮肤恶性肿瘤,其多数发生淋巴结或血液远处转移,转移性恶性黑色素患者5年生存率仅5%～10%,转移是恶性黑色素瘤患者存活率低的重要原因。长链非编码RNA（long non-coding RNA,lncRNA）是不具备蛋白质编码功能且长度普遍大于200个核苷酸的RNA分子,lncRNA差异性表达可能通过调节上皮-间质转化(EMT)相关因素、改变细胞外基质（ECM）性能等环节促进或抑制恶性黑色素瘤的增殖、侵袭和转移过程。本文综述了lncRNA在恶性黑色素瘤侵袭和转移中作用的研究进展,旨在为恶性黑色素瘤转移的早期诊断及预后预测寻找新的标志物。     

Role of proteolytic enzymes in human prostate bone metastasis formation: in vivo and in vitro studies

Prostate cancers ability to invade and grow in bone marrow stroma is thought to be due in part to degradative enzymes. The formation of prostate skeletal metastases have been reproduced in vitro by growing co-cultures of prostatic epithelial cells in bone marrow stroma. Expression of urokinase plasminogen activator, matrix metalloproteinase 1 and 7 by prostatic epithelial cells were identified using immunocytochemistry. Also, in vivo tissue sections from human prostatic bone marrow metastases were stained. To establish the role of these enzymes on colony formation, inhibitory antibodies directed against urokinase plasminogen activator, matrix metalloproteinase 1 and matrix metalloproteinase 7 were added into primary prostatic epithelial cells and bone marrow stroma co-cultures. All prostatic epithelial cell cultures stained positively for matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator. Generally prostatic epithelial cells derived from malignant tissues showed increased staining in comparison to epithelia derived from non-malignant tissue. In agreement with in vitro co-cultures, the in vivo tissue sections of prostate bone marrow metastases showed positive staining for all three enzymes. Inhibition studies demonstrated that blocking matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator function reduced the median epithelial colony area significantly in bone marrow stroma co-cultures in vitro. Using a human ex-vivo model we have shown that matrix metalloproteinase 1, matrix metalloproteinase 7 and urokinase plasminogen activator play an important role in the establishment of prostatic epithelial cells within bone marrow.     

Inhibition of invasion and experimental metastasis of murine melanoma cells by human soluble thrombomodulin

Thrombomodulin (TM) is an anticoagulant molecule expressed on the endothelial cell surface and soluble TM antigen, which is present in human plasma and urine, represents the products of limited proteolytic cleavage of cell-surface TM. Recently, it was demonstrated that TM is also expressed on the surface of several tumor cells and the expression level of TM negatively correlated with malignancy in cancer. We investigated the effect of soluble TM isolated from human urine (uTM) on the invasion and metastasis of murine melanoma cells (B16F10 cells) through a reconstituted basement membrane (Matrigel) and in a murine model of experimental lung metastasis. Matrigel reconstituted with uTM inhibited the invasion of B16F10 cells in a dose-dependent manner in a range from 10 to 1000 ng/ml uTM as compared with the control Matrigel without uTM. The inhibitory action of uTM was not altered in the presence of an excess amount of hirudin, an inhibitor of thrombin proteolytic activity, but abolished in the presence of anti-human TM IgG. Matrigel reconstituted with thrombin (1 NIH unit/ml) enhanced the invasion level of cells by 1.5-fold relative to the control Matrigel without thrombin. The thrombin-enhanced invasion of B16F10 cells was repressed by addition of hirudin (10 units/ml) or uTM (100 ng/ml) into the Matrigel. Matrigel reconstituted with hirudin (10 units/ml) and uTM (100 ng/ml) additionally accelerated the inhibitory activity of hirudin or uTM on the thrombin-enhanced invasion of B16F10 cells. Moreover, metastatic colonies formed in the lungs of mice injected intravenously with B16F10 cells were significantly reduced by injection of uTM once a day up to 2 days after co-injection of uTM with the cells. These results suggested that Matrigel reconstituted with uTM inhibited the invasion of B16F10 cells in vitro through a thrombin-independent mechanism and the injection of uTM suppressed experimental lung metastasis of the cells in mice.     

Differentiation and metastasis in melanoma

The incidence of melanoma has been rising steadily during the last four decades and is now among the highest of all human cancers. As for most tumors, malignancy and metastatic spreading represent the deadly aspects of a tumor that, if eradicated before becoming invasive, can be easily cured. In fact, melanoma metastatic to regional lymph nodes carries a poor prognosis, and distant metastatic melanoma becomes incurable. Because traditional forms of chemotherapy have little effect on this type of tumor, differentiation therapy has been considered as a possible alternative, based on the consideration that malignancy and differentiation are usually inversely related. However, the relationship between these two factors turned out to be more complex for melanoma cells, and in some murine model systems it has been found that differentiated cells, although less tumorigenic, could be even more metastatic. No clear correlation has been reported between (epi)genetic changes induced by differentiating drugs and the increased malignant phenotype. This review examines what is known to date about differentiation state and metastatic ability of melanomas, and also reports some novel data with the B16 mouse melanoma model system.     

Lymph node metastasis of melanoma of unknown primary tumor]

Sixteen patients with clinical stage II melanoma of unknown primary site (regional lymph node metastasis) were followed up between 1978 and 1988. The 5-year survival rate was 47%. These results seem to parallel those for stage II disease with known primary tumor sites, as has been observed in other data from the literature. The hypotheses put forward to explain such lesions are the spontaneous regression of the primary tumor, and the onset of primary malignant melanoma in the lymph nodes.     

Cancer invasion and metastasis

Metastasis is the transfer of malignant tumors from one organ to a distant organ. It is the most common cause of death in cancer patients. Different molecular mechanisms enable tumor cells to infiltrate the surrounding tissue, invade blood vessels and leave the blood stream at a different site. Tumor cell interaction with extracellular matrix components and epithelial-mesenchymal transition as well as angiogenesis are important factors in invasion and metastasis. Gene expression profiles of metastatic cells in various organs are different and not every tumor cell has the capacity to metastasize. The microenvironment in the organ influences formation of metastasis. Only 1% of micrometastases progress into macrometastases.     

Evaluation of changes in the activity of proteolytic enzymes and their inhibitors in the processes that accompany the growth of gastric cancer

Background Many investigators have observed a correlation between the aggressiveness of malignant tumor growth and the levels of cysteine peptidases and their autogenous inhibitors. Cathepsins B and L are activated by pepsin in an acidic pH. This fact encouraged us to measure the activity of these enzymes in tissue samples of gastric cancer.Methods We measured the activities of cathepsins B and L, and their precursors and inhibitors, in homogenates of tissue samples obtained from operations for gastric cancer. We compared the results for the homogenates of tissues from three different sites: the tumor center, the zone of cancer invasion (border of the tumor), and healthy tissue.Results The highest activities of free cysteine peptidases and those in complexes with their inhibitors, as well as their precursors, were observed in the border of the tumor, while the activities in healthy tissue were significantly lower.Conclusion The local activities of cysteine peptidases and their inhibitors reflect the topographical differences between the center of the tumor, the zone of invasion, and healthy tissues in gastric cancer patients. In addition, the results for the pattern of changes in the activity of cysteine peptidases according to the degree of tissue infiltration were not dependent on the method of measurement (colorimetry vs spectrofluorometry).     

尿激酶纤溶酶原激活物系统与肿瘤侵袭转移

恶性肿瘤合成分泌大量胞外蛋白水解酶,降解细胞外基质及基底膜,是恶性肿瘤侵袭转移的重要基础.尿激酶纤溶酶原激活物(uPA)系统作为主要的蛋白水解酶在其中发挥重要作用.本简述uPA系统的结构、功能及其在侵袭、转移中的作用.     

Monoclonal antibody 4C5 immunostains human melanomas and inhibits melanoma cell invasion and metastasis.

PURPOSE: Tumor cell metastasis constitutes a major problem in the treatment of cancer. Because the cure rate of metastatic tumors is very low, new therapeutic approaches are needed. Heat shock protein 90 (HSP90) is a molecular chaperone that is recognized as a new target for the treatment of cancer. Here, we examine the value of a monoclonal antibody (mAb) against HSP90, mAb 4C5, as a potential marker in malignant melanomas. Moreover, we investigate the possibility to use mAb 4C5 as an inhibitor of melanoma cell invasion and metastasis. EXPERIMENTAL DESIGN: Paraffin blocks of formalin-fixed human melanoma tumor tissues were used to prepare tissue microarrays. The B16 F10 melanoma cell line was used in all the in vitro experiments. To assess melanoma cell invasion, the wound-healing assay and the Matrigel invasion assay were applied. To evaluate the effect of mAb 4C5 on tumor metastasis, we used an experimental model of metastatic melanoma. RESULTS: Immunohistochemical studies done on a panel of malignant melanomas showed positive immunostaining with mAb 4C5 in all cases. mAb 4C5 inhibits B16 F10 cell invasion by binding to surface HSP90 because it is not internalized. mAb 4C5 significantly inhibits melanoma metastasis in C57BL/6 mice inoculated with B16 F10 cells. CONCLUSIONS: mAb 4C5 could be potentially used as a novel specific marker for malignant melanomas. mAb 4C5 inhibits melanoma cell invasion in vitro by binding to cell surface HSP90 expressed on B16 F10 melanoma cells. Finally, this antibody significantly inhibits melanoma metastasis, thus rendering it a potential therapeutic agent for the treatment of cancer metastasis.     

Fibronectin and integrins in invasion and metastasis

Summary The adhesive glycoprotein fibronectin and integrin receptors appear to play important roles in the progression of metastatic disease. Fibronectin is a multifunctional extracellular glycoprotein that has at least two independent cell adhesion regions with different receptor specificities. The cell adhesive region in the central portion of fibronectin is comprised of at least two minimal amino acid sequences - an Arg-Gly-Asp (RGD) sequence and a Pro-His-Ser-Arg-Asn (PHSRN) sequence - which function in synergy. Another cell adhesive region is located near the carboxy-terminus in the alternatively spliced IIICS module. The critical minimal sequences for this region are Leu-Asp-Val (LDV) and Arg-Glu-Asp-Val (REDV) which function in an additive rather than synergistic fashion. Integrins are heterodimeric, transmembrane cell adhesion receptors for fibronectin and other extracellular matrix molecules. Several different integrins bind to fibronectin. The ₅₁ fibronectin-specific integrin binds to the central RGD/PHSRN site. The ₄₁ integrin binds to the IIICS site. Fibronectin-integrin interactions are important in tumor cell migration, invasion, and metastasis. In addition to promoting cell adhesion to the extracellular matrix, these proteins may also function in chemotaxis and control of proliferation. Peptide and antibody inhibitors of fibronectin and integrin functions have been shown to be effective inhibitors of metastasis, and are potentially important reagents for the study and control of cancer.