Biological evaluation of novel 6-Arylbenzimidazo [1.2-c] quinazoline derivatives as inhibitors of LPS-induced TNF- alpha secretion

This study describes the effect of novel 6-Arylbenzimidazo [1,2-c] quinazoline derivatives as tumor necrosis factor alpha (TNF-á) production inhibitors. The newly synthesized compounds were tested for their in vitro ability to inhibit the lipolysaccharide (LPS) induced TNF-á secretion in the human promyelocytic cell line HL-60. The compound 6-Phenyl-benzimidazo [1,2-c] quinazoline, coded as Gl, resulted as the most potent inhibitor and with no significant cytotoxic activity. Thus, 6-Arylbenzimidazo [1,2-c] quinazoline derivatives may have a potential as anti-inflammatory agents.

Phospholipase D activity is elevated in hepatitis C virus core protein-transformed NIH3T3 mouse fibroblast cells

Hepatitis C Virus (HCV) is associated with a severe liver disease and increased frequency in the development of hepatocellular carcinoma. Overexpression of HCV core protein is known to transform fibroblast cells. Phospholipase D (PLD) activity is commonly elevated in response to mitogenic signals, and has also been overexpressed and hyperactivated in some human cancer cells. The aim of this study was to understand how PLD was regulated in the HCV core protein-transformed NIH3T3 mouse fibroblast cells. We observed that PLD activity was elevated in the NIH3T3 cells overexpressing HCV core protein over the vector alone-transfected control cells, however, expression levels of PLD protein and protein kinase C (PKC) in the HCV core protein-transformed cells was similar to the control cells. Phorbol 12-myristate 13-acetate (PMA), which is known to activate PKC, stimulated PLD activity significantly more in the core protein-transformed cells, in comparison with that of the control cells. PLD activity assay using PKC isozyme-specific inhibitor and PKC translocation experiment showed that PKC-delta was mainly involved in the PMA- induced PLD activation in the core-transformed cells. Moreover, in cells overexpressing HCV core protein, PMA also stimulated p38 kinase more potently than that of the control cells, and an inhibitor of p38 kinase abolished PMA-induced PLD activation in cells overexpressing HCV core protein. Taken together, these results suggest that PLD might be implicated in core protein-induced transformation.

Der f 2 activates phospholipase D in human T lymphocytes from Dermatophagoides farinae specific allergic individuals: Involvement of protein kinase C-alpha

The major house-dust mite allergen, Der f 2, stimulates the phospholipase D (PLD) in T lymphocytes from Dermatophagoides farinae specific allergic individuals. PLD activity increased more than two-fold in T cells from allergic patients compared with those cells from normal controls with maximal responses within 30 min after exposure of Der f 2. A well-known PLD activator PKC-alpha was found to be translocated to membrane from cytosol in Der f 2-treated T cells from Dermatophagoides farinae specific allergic individuals. Down-regulation of PKC-alpha with phorbol myristate acetate pretreatment for 24 h abolished Der f 2-induced PLD activation. Ro 320432, PKC inhibitor also reduced the effects of Der f 2-induced PLD activation suggesting that PKC-alpha acts as upstream activator of PLD in Der f 2-treated T cells. Taken together, the present data suggest that Der f 2 can stimulate PLD activity through the PKC-alpha activation in T cells from Dermatophagoides farinae allergic individuals