Raised levels of latent collagenase activating angiogenesis factor (ESAF) are present in actively growing human intracranial tumours

Keratose hydrogel for tissue regeneration and drug delivery

Keratin (KRT), a natural fibrous structural protein, can be classified into two categories: "soft" cytosolic KRT that is primarily found in the epithelia tissues (e.g., skin, the inner lining of digestive tract) and "hard" KRT that is mainly found in the protective tissues (e.g., hair, horn). The latter is the predominant form of KRT widely used in biomedical research. The oxidized form of extracted KRT is exclusively denoted as keratose (KOS) while the reduced form of KRT is termed as kerateine (KRTN). KOS can be processed into various forms (e.g., hydrogel, films, fibers, and coatings) for different biomedical applications. KRT/KOS offers numerous advantages over other types of biomaterials, such as bioactivity, biocompatibility, degradability, immune/inflammatory privileges, mechanical resilience, chemical manipulability, and easy accessibility. As a result, KRT/KOS has attracted considerable attention and led to a large number of publications associated with this biomaterial over the past few decades; however, most (if not all) of the published review articles focus on KRT regarding its molecular structure, biochemical/biophysical properties, bioactivity, biocompatibility, drug/cell delivery, and in vivo transplantation, as well as its applications in biotechnical products and medical devices. Current progress that is directly associated with KOS applications in tissue regeneration and drug delivery appears an important topic that merits a commentary. To this end, the present review aims to summarize the current progress of KOS-associated biomedical applications, especially focusing on the in vitro and in vivo effects of KOS hydrogel on cultured cells and tissue regeneration following skin injury, skeletal muscle loss, peripheral nerve injury, and cardiac infarction.

Immunohistochemical Demonstration of Vascular Endothelial Growth Factor in Vestibular Schwannomas Correlates to Tumor Growth Rate

OBJECTIVE

Vascular endothelial growth factor (VEGF) is one of the most potent mediators of angiogenesis, which is a mandatory process during tumor growth. The present objectives were to determine expression of VEGF in vestibular schwannomas by immunohistochemistry and to examine a possible correlation with symptom duration, tumor size, or growth rate.

STUDY DESIGN

Retrospective patient file review; immunohistochemistry and light microscopy of vestibular schwannomas removed by surgery.

METHODS

Vestibular schwannomas from 18 patients were immunolabelled using a polyclonal antibody against VEGF, followed by light microscopy and blinded semiquantitation of VEGF expression. Fifteen patients had a well-defined tumor growth rate defined by repeated preoperative magnetic resonance imaging scans.

RESULTS

All tumors showed expression of VEGF in the Schwann cell cytoplasm, with a more intense staining of the perinuclear region of some cells. The staining intensity varied from tumor to tumor, and semiquantitation revealed a significant correlation between VEGF expression and tumor growth rate, but not symptom duration or tumor size.

CONCLUSION

VEGF is expressed in vestibular schwannomas and the level of expression correlates positively with tumor growth rate, but not with tumor size and symptom duration. We conclude that VEGF seems to be a factor involved in the growth of vestibular schwannomas.

Suppression of cell invasion on human malignant glioma cell lines by a novel matrix-metalloproteinase inhibitor SI-27: in vitro study

Matrix metalloproteinase (MMP) has come to be highlighted by its close relation to the cell invasion of gliomas. Suppression of MMP activity in malignant glioma cells would be meriting to local delivery of genes or chemotherapeutic agents. In this study, we employed a novel MMP inhibitor, SI-27 to investigate inhibition of cell invasiveness in human malignant glioma cell lines, U87MG, U251MG, and U373MG. We evaluated with zymogram, reverse zymogram, and cell invasion assay after exposure of SI-27 for 24 h followed by preliminary MTT assay to find non-cytotoxic dose range, 5, 10, 50, 100 microg/ml compared with non-treatment group as the control. Common to three glioma cell lines, zymogram disclosed that expressions of MMP-2 and -9 were suppressed in a dose-dependent fashion, meanwhile those of tissue inhibitor of MMP (TIMMP) in reverse zymogram were not. The numbers of invading cells through Boyden chamber were significantly reduced in a dose-dependent manner, while those with 5 microg/ml were not diminished common to those three lines. In conclusion, dose concentration ranging 10-100 microg/ml of SI-27 inhibited MMP-2 and -9 mediated cell invasiveness in malignant glioma cell lines. This is the first report for chemotherapeutic effect of SI-27 on glioma cells.

Endothelial cell stimulating angiogenesis factor

Endothelial cell stimulating angiogenesis factor (ESAF) is a small (> 1000 Da) dialysable non-peptide molecule with potent angiogenic activity. ESAF activates the major pro-matrix metalloproteinases and also uniquely reactivates the complex of these active enzymes with their tissue inhibitors resulting in both active enzyme and inhibitor. These actions may be pivotal in its role as an angiogenic factor. ESAF is primarily involved in angiogenic conditions where inflammatory cells are not evident such as foetal bone growth and electrically stimulated skeletal muscles and proliferative retinopathy. However, high levels also occur in actively growing human intracranial tumours but it is not noticeably elevated in rheumatoid arthritic synovial fluid. Its extreme potency and low molecular mass make its structural determination difficult. Possible therapeutic applications would be in the treatment of ischaemic ulcers, acceleration of fracture repair, infertility and more modestly in the correction of baldness. Analogues of ESAF could be of value in treating angiogenic diseases such as psoriasis and proliferative retinopathy.

Tumor angiogenesis--a new therapeutic target in gliomas

Tumor growth is critically dependent on angiogenesis, which is sprouting of new vessels from pre-existing vasculature. This process is regulated by inducers and inhibitors released from tumor cells, endothelial cells, and macrophages. Brain tumors, especially glioblastoma multiforme, have significant angiogenic activity primarily by the expression of the angiogenic factor VEGF Anti-angiogenic therapy represents a new promising therapeutic modality in solid tumors. Several agents are currently under evaluation in clinical trials. The present review describes the principal inducers and inhibitors of angiogenesis in tumors and summarizes what is known about their mechanisms of action in relation to CNS tumors. Potential areas for clinical use are also discussed.

Suppression of matrix metalloproteinase-2-mediated cell invasion in U87MG, human glioma cells by anti-microtubule agent: in vitro study

Because microtubules are important components of cell motility and intracellular transport, it is reasonable to propose that the depolymerizing effect of an antimicrotubule agent, estramustine, on glioma microtubules would modulate cell invasiveness. To determine whether matrix metalloproteinases, key factors in cell invasion, are affected by exposure to estramustine, a cell proliferation assay, a zymogram, a collagenolysis assay and a haptoinvasion assay were used in this study. The zymogram revealed that an activated (62 kDa) form of matrix metalloproteinase-2 diminished with increasing estramustine concentrations. The collagenolysis assay demonstrated approximately 2.5- to 21-fold lower rates of enzymatic activity suppressed by estramustine in a dose-dependent manner at estramustine concentrations of 1, 5, and 10 microM, compared with the control group. On the haptoinvasion assay, no statistically significant difference was seen in the 0.5 microM estramustine group, whereas 1-10 microM estramustine groups revealed significant suppression of invasion from 6 to 24 h in a dose-dependent manner. The results suggest that estramustine suppresses the invasion of U87MG cells in vitro using the decreasing available matrix metalloproteinase-2, an effect caused by the disassembly of microtubules. Suppression of the infiltrative capacity of malignant glioma cells could be of significant value in the treatment of this disease.

Degradation of collagen type IV by C6 astrocytoma cells

The key event associated with the initiation of angiogenesis is the localized degradation of the vascular basement membrane. Because of its complex structure, any remodelling and/or modification of the basement membrane must involve the co-ordinated function of a number of different enzyme systems. Type IV collagen is a major protein component (60-90%) of the basement membrane and its degradation is crucial to the initiation of angiogenesis. This study has focused on the mechanisms by which C6 astrocytoma cells degrade human type IV collagen. C6 astrocytoma cells use components of two major degradative pathways to degrade collagen type IV. The major matrix metalloproteinase identified is the activated form (68-KDa) of gelatinase A (72-KDa matrix metalloproteinase) and a serine sensitive 1000-KDa collagenase type IV degrading activity which appears to have the characteristics of a novel extracellular proteasome.

Molecular and cellular basis of cancer invasion and metastasis: implications for treatment

In the past decade significant advances in establishing the underlying biological mechanisms of tumour invasion and metastasis have been made. Some of the triggering factors and genes relevant to metastatic spread have been identified. Advances have also been made in understanding the signal transduction pathways involved in invasion and metastasis. This increased comprehension of the malignant metastatic process has enabled new antimetastatic strategies to be devised. This review summarizes progress in these areas and discusses the implications for the treatment of metastasis.

Localization of type I human skin collagenase in developing embryonic and fetal skin

Type I human skin collagenase (HSC-1) was localized in developing embryonic and fetal skin ranging from 6 to 20 weeks estimated gestational age using an antigen-specific, affinity-purified, polyclonal antiserum to HSC-1 and an avidin-biotin alkaline phosphatase procedure. Double immunolabeling with monoclonal antibodies for Factor VIII-related antigen, type IV collagen, and the 68-kilodalton neurofilament subunit was performed using a direct peroxidase procedure. By 8 weeks estimated gestational age, HSC-1 localized to the periderm, the basal cell epidermal keratinocytes, dermal fibroblasts, and surrounding extracellular matrix. At 12 weeks estimated gestational age, HSC-1 immunolabeling showed a continued association with the epidermis and dermis. Dermal and subcutaneous blood vessels and the surrounding extracellular matrix were positive for HSC-1 labeling. HSC-1 staining was also found around developing nerves and in association with dermal fibroblasts. In the developing hair follicle, HSC-1 was present in keratinocytes of the pre-germ, germ, hair peg, and bulbous hair peg. HSC-1 immunoreactivity was also found in association with the hair canal, the bulge, and the dermal papillae, but was absent from the fetal sebaceous gland. These data demonstrate the association of HSC-1 with the development of interfollicular epidermis, the dermal collagenous matrix, the process of angiogenesis, the development of nerves, and hair follicle morphogenesis.

AGM-1470 inhibits the growth of human glioblastoma cells in vitro and in vivo

Glioblastoma is the most malignant primary brain tumor. Inhibition of angiogenesis is one potential strategy for treating this fatal hypervascular tumor. AGM-1470 (also called TNP-470), a novel, potent, fungus-derived inhibitor of angiogenesis, was tested on the growth of human glioblastoma cells in culture and on the growth of the tumor in nude mice. In nude mice with subrenally implanted U-87 MG glioblastomas, AGM-1470 significantly inhibited tumor growth (P < 0.01), and in nude mice with intracranial U-87 MG glioblastomas, AGM-1470 prolonged survival. In addition to its expected action as an angiogenesis inhibitor, AGM-1470 also directly inhibited U-87 MG cells in culture at concentrations similar to those that inhibited endothelial cells. The combined inhibition of glioblastoma cell mitosis and of glioblastoma-induced neovascularization suggests that AGM-1470 should be considered for further investigation in the treatment of this fatal tumor.

Inhibition of collagenolytic activity relates to quantitative reduction of invasion in vitro in a c-Ha-ras transfected glial cell line

The function of proteases in brain tumor invasion is currently not well established. For tumors of epithelial and fibromatous origin collagenase production can enhance the invasive capacity of cells to penetrate basement membranes. We showed previously that a c-Ha-ras transformed glial cell line (CxT24neo3) invaded hamster brain tissue in vivo. These cells were also capable of invading reconstituted basement membrane and embryonic chick hearts in vitro. Since the histopathology of CxT24neo3 tumors mimics that of glioblastoma multiforme in humans, CxT24neo3 was used as the model in vitro for this type of brain tumor. Presently, we detected by zymogram analysis a gelatinase that was secreted by CxT24neo3 and that had an apparent molecular mass of 62 kD. To verify whether gelatinase affected invasion in vitro of these glial cells we determined the efficacy of a substrate specific collagenase inhibitor on invasion in vitro. GM6001 is a synthetic polypeptide that specifically occupies the substrate binding sites of metalloprotease. Since this drug did not show cytotoxicity, its specificity for metalloprotease is a valuable tool to evaluate the physiological function of these enzymes on invasion. We found that treatment of CxT24neo3 with GM6001 reduced the fraction of invading CxT24neo3 cells through reconstituted basement membrane. These data suggest that metalloproteases can stimulate brain tumor invasion.