Tumor gelatinases and invasion inhibited by the green tea flavanol epigallocatechin-3-gallate

BACKGROUND: Given the association of consumption of green tea with prevention of cancer development, metastasis, and angiogenesis, the effect of the main flavanol present, epigallocatechin-3-gallate (EGCG), on two gelatinases most frequently overexpressed in cancer and angiogenesis (MMP-2 and MMP-9) and on tumor cell invasion and chemotaxis were examined. METHODS: Zymography, Western blotting, and enzyme linked immuoadsorbent assay were used to analyze the effect of EGCG on MMP-2 and MMP-9 activity, whereas its effect on tumor cell invasion and chemotaxis was examined using modified Boyden chamber assays. RESULTS: A Zn2+ chelation-independent, dose-dependent, noncompetitive inhibition by EGCG of both gelatinases was found at concentrations 500 times lower than that reported to inhibit urokinase. Tumor cell invasion of a reconstituted basement membrane matrix, but not chemotaxis, was reduced by 50% with EGCG concentrations equivalent to that in the plasma of moderate green tea drinkers, and 2 orders of magnitude below those of tissue inhibitors of MMPs. Although higher concentrations of EGCG were associated with increased levels of both cell-associated gelatinases and their activator MT1-MMP, no increased gelatinase activation was found, and TIMP-1 and TIMP-2 inhibitors were up-regulated. Finally, concentrations of EGCG active in restraining proliferation and inducing apoptosis of transformed cells were more than 100 times lower than those reported for normal cells. CONCLUSIONS: Epigallocatechin-3-gallate is a potent inhibitor of gelatinases and an orally available pharmacologic agent that may confer the antiangiogenic and antimetastatic activity associated with green tea.     

Spontaneous production of interleukin-6 by alveolar macrophages from human immunodeficiency virus type 1-infected patients.

To test the hypothesis that the lung represents a source of interleukin (IL)-6 in human immunodeficiency virus type 1 (HIV-1)-positive subjects, alveolar macrophages (AM) obtained from the bronchoalveolar lavage (BAL) fluid of 10 HIV-1-positive patients were investigated for the expression of IL-6 mRNA and the ability to release IL-6. The presence of IL-6 in BAL fluid was also investigated. It has been demonstrated that freshly recovered AM from HIV-1-positive patients show a strong IL-6 mRNA signal. The message for IL-6 increases following culture with LPS. Supernatants obtained from AM cultured in medium alone contain high amounts of IL-6; the values are three to four times higher following culture with LPS. IL-6 has also been detected in the BAL fluid from 5 of 8 HIV-1-positive patients. Results of immunoblotting analysis were consistent with those given above. These findings suggest that the lung represents a source of IL-6 production in HIV-1-infected subjects with lung disorders.     

Behaviour of basement membrane antigens in gastric and colorectal cancer. Immunohistochemical study

Eighty gastric and colorectal lesions including cases of dysplasia and carcinoma were studied by immunohistochemical techniques to investigate the behaviour of laminin, type IV collagen and fibronectin. Their distribution was examined on frozen and formalin-fixed, paraffin-embedded samples. In the same lesions, interruption, fragmentation and absence of basement membrane (BM) antigen-staining were observed. Carcinomas with well differentiated glandular structures were always surrounded by a well defined BM as in normal, non-pathological tissues. On the contrary, undifferentiated areas arranged in nests or sheets were usually negative for laminin and type IV collagen. Anomalous BM staining was strictly related to the degree of differentiation of tumor tissue, while no correlation existed between carcinoma staging and BM antigen presence, either in gastric or colorectal neoplasms. Immunostaining with antibody against type IV collagenase showed a massive positivity in the early gastric carcinomas examined, while in colorectal cancer only granulocytes showed it.     

Structural organization of collagen fibrils in media aortic wall.

Small-angle X-ray diffraction patterns of bovine, human and porcine media aortic wall show meridional reflections corresponding to a periodicity which suggest a molecular packing typical of tendon collagen. However the meridional intensity distribution of stretched air dried aortic samples appears different from that of air-dried tendon, probably because of the presence of a large amount of type III collagen with the environment, which are specific for aortic tissue. The stretched wet aortic samples show a marked decrease in intensity, revealing an extensive disorder in the axially-projected structure of the fibrils. When a loading system simulating the effect of blood pressure is applied to a ring of aorta, no evidence of orientation of collagen is seen by X-ray diffraction, as would be expected if collagen fibrils had an isotropic distribution inside the aorta media. Scanning electroni microscopy supports the existence of a network of collagen fibrils surrounding elastic lamellae.