Novel approach to analysis of in vitro tumor angiogenesis with a variable-pressure scanning electron microscope: suppression by matrix metalloproteinase inhibitor SI-27

3D tumor spheroids: an overview on the tools and techniques used for their analysis

In comparison with 2D cell culture models, 3D spheroids are able to accurately mimic some features of solid tumors, such as their spatial architecture, physiological responses, secretion of soluble mediators, gene expression patterns and drug resistance mechanisms. These unique characteristics highlight the potential of 3D cellular aggregates to be used as in vitro models for screening new anticancer therapeutics, both at a small and large scale. Nevertheless, few reports have focused on describing the tools and techniques currently available to extract significant biological data from these models. Such information will be fundamental to drug and therapeutic discovery process using 3D cell culture models. The present review provides an overview of the techniques that can be employed to characterize and evaluate the efficacy of anticancer therapeutics in 3D tumor spheroids.

Expression of MMP, HPSE, and FAP in stroma promoted corneal neovascularization induced by different etiological factors

PURPOSE

To observe the relationship between the expression of matrix metalloproteinases (MMP-2, MMP-9), heparanase (HPSE), and fibroblast activation protein (FAP) in stroma and corneal neovascularization induced by different etiological factors.

METHODS

Five models were established: alkaline burn, fungal infection, suturing, immunogen implantation, and tumor cell implantation. The ingrowth time and morphology of corneal neovascularization in each model was observed by slit lamp. Inflammation and neovascularization in the corneal stroma were examined by histopathology. MMP-2, MMP-9, HPSE, and FAP were detected by immunohistochemistry or double immunofluorescence staining.

RESULTS

The neovascular vessels started to invade the cornea from the third day in each model. The corneal neovascularization presented dendritic-form, brush-form, and triangle-form in alkaline burn, fungal infection, and suturing models, respectively, and reached to the central cornea in the latter two models. The inflammatory cells appeared in the stroma on the first day, while neovascular vessels grew into the stroma from the third day and both of them accompanied each other from 3-14 days in each model. MMP-2, MMP-9, and HPSE appeared before the neovascularization on the first day and accompanied it from 3-14 days in each model. FAP(+) cells occurred mainly around CD31(+) vascular endothelial cells in each model.

CONCLUSION

The corneal neovascularization induced by different etiological factors have different morphologies. The inflammation and the expression of MMP, HPSE, and FAP in stroma may serve as pioneers for the growth of corneal neovascularization.

Participation of the matrix metalloproteinase inhibitor in Thy-1 nephritis

What influence would be shown in Thy-1 glomerulonephritis when the synthetic matrix metalloproteinase (MMP) inhibitor SI-27 is administered? Five groups of 80 male Wistar rats were studied: healthy group; treated healthy group; nephritic group; pretreated nephritic group; and post-treated nephritic group. SI-27 treatment of nephritic animals was initiated either 2 days before or 2 days after anti-Thy-1.1 antibody injection. On days 7, 14, 26 and 42 after disease induction, we examined renal histology, extracellular matrix (ECM) constituent, and MMP activity. SI-27 treated Thy-1 groups resulted in significant reduction of glomerular cells including alpha-smooth muscle actin (alpha-SMA) positive mesangial cells and suppressed expression of type IV collagen at 7 days. Moreover, type I collagen was also decreased by SI-27 at 42 days. However, glomerular cell numbers did not show any significant changes at 14, 26 and 42 days. In gelatin zymography, the gelatinolytic band for MMP-9 was expressed in SI-27 treated Thy-1 nephritis groups, although it was not expressed in the nephritic group at day 7. However, the expression of MMP-9 was no longer seen at 14, 26 and 42 days. The bands for an active form of MMP-2 were expressed throughout the experimental period in the Thy-1 nephritic groups. These results suggest that MMP plays an important role in the development of Thy-1 nephritis, and even if the synthetic MMP inhibitor intercepts the initial increase of glomerular cells and matrices, it does not inhibit recovery to normal glomerular capillary structures in Thy-1 nephritis.

The expression of matrix metalloproteinase-2 and -9 in human gliomas of different pathological grades

Matrix metalloproteinases (MMPs) have been implicated to play a critical role in glioma invasiveness. In this study, we aimed to investigate the expression of MMP-2 and MMP-9 in human gliomas of different degrees of malignancy, and evaluated the correlation between MMP-2 and MMP-9 expression in gliomas. The samples from 65 cases of glioma were divided into four groups according to the WHO classification: there were 16 cases of grade I, 17 cases of grade II, 20 cases of grade III, and 12 cases of grade IV. Normal brain samples served as the control group, and biopsy specimens were obtained from 8 glioma patients with a needle placed into the adjacent brain 1 cm from the margin after tumor resection. All the samples were stained with hematoxylin and eosin and immunohistochemistry. A computer-aided image-analysis system was employed to measure the integral optical density (IOD) of positive slides. No positive staining was found in the control group. The positive staining was localized in the cytoplasm of glioma cells, the extracellular matrix (ECM), the basement membrane (BM), and the endothelial cells of blood vessels. Positive staining rates increased significantly when the degree of malignancy of gliomas was elevated. The IOD value of MMP-2 and MMP-9 also indicated that the intensity of MMP-2 and MMP-9 expression was elevated significantly with the degree of malignancy of the gliomas. There was a positive correlation between MMP-2 and MMP-9 expression in gliomas. Glioma invasion and angiogenesis were particularly seen in the biopsied tissues, and MMP-9 immunostaining seemed to be much more intense and extensive than MMP-2 immunostaining in these samples. These results suggest that MMP-2 and MMP-9 staining in gliomas is localized in the cytoplasm of tumor cells, BM, and endothelial cells, and that MMP-2 and MMP-9 together play an important role in the invasiveness of gliomas, mediating the degradation of the ECM and angiogenesis. MMP-2 and MMP-9 could be molecular targets in the treatment of malignant glioma.

Drug-induced apoptosis by a matrix metalloproteinase inhibitor, SI-27 on human malignant glioma cell lines; in vitro study

Matrix metalloproteinase (MMP) plays important roles in cell invasion and tumor angiogenesis. SI-27, an anti-MMP agent, has already been shown to possess both in vitro anti-invasive and anti-angiogenic properties against malignant gliomas in non-cytotoxic dose concentrations. However, to the best of our knowledge, the molecular mechanism mediating the cytotoxic action by this agent and the molecular mechanism in the cytotoxic action against malignant glioma cell have not yet been clarified. Therefore, we assessed the effect in the cytotoxic dose concentrations to investigate whether this cytotoxic action is related to apoptosis in this study. The effect on human glioma cell lines (U87MG, U251MG, and U373MG) was examined by transmission electron microscope, agarose gel electrophoresis with the DNA fragmentation, flow cytometry with FITC-conjugated Annexin V, and detection of caspase activity. Drug-induced apoptosis was observed in the cytotoxic dose. The result indicated that the cytotoxity of SI-27 might be related to the drug-induced apoptosis mediated by caspase.

Apoptotic induction by BE16627B on human malignant glioma cell lines by an anti-matrix metalloproteinase agent

We have elucidated the pharmacological action of the anti-matrix metalloproteinase inhibitor BE16627B on glioma cells. The study was limited to the noncytotoxic dose range. The aim of the study was to investigate whether the cytotoxicity of BE16627B, an anti-MMP agent, is related to apoptosis in the human malignant glioma cell lines U87MG, U251MG, and U373MG. MTT assay was performed to detect the cytotoxic dose range. Agarose gel electrophoresis was performed with purified genomic DNA following exposure to 20 to 500 microM BE16627B for 24 h, compared with 0 microM for the control group. Transmission electron microscopy (TEM) was employed to study nuclear fragmentation following exposure to 0, 20, and 500 microM of the agent for 24 h. An in situ endolabeling assay was performed to determine the index of apoptotic induction. MTT assay revealed that concentrations of 100 microM and above were cytotoxic. DNA laddering was demonstrated in agarose gel electrophoresis. TEM disclosed condensing and fragmentation of the chromatin. None of these changes were observed in the control group and the noncytotoxic dose group. The in situ endolabeling study disclosed that the apoptotic index was significantly elevated by cytotoxic doses of this agent (U373MG; control, 4.0%; 500 microM, 68.5%). These results indicated that cytotoxic concentrations of BE16627B induced apoptosis in human malignant glioma cell lines. In our previous report, this agent inhibited activity of MMP in noncytotoxic concentrations. Further study should be done to determine the pharmacological action of toxic BE16627B.