Angiogenesis is an important therapeutic target in cancer, and to fully exploit its therapeutic potential, combination chemotherapeutic/antiangiogenic regimens should be optimized and delivered earlier to more patients. Ideally, this could be done by a single potent oral agent with established safety. Rifampicin, a semisynthetic antibiotic derived from the rifamycins, is one of the most commonly used pharmaceutical compounds worldwide in the treatment of tuberculosis. Here, we present the effects of oral rifampicin on human cancer progression and its antiangiogenic properties, which were comparable to the angiogenesis inhibitor endostatin. Clinically, low-dose p.o. administration of rifampicin to six high-risk patients with hepatitis C virus-related liver cirrhosis resulted in a single occurrence of hepatocellular carcinoma during the follow-up period of 97.3 +/- 29.1 (mean +/- SD) months. Experimentally, rifampicin rapidly and markedly down-regulated the expression of a wide spectrum of angiogenesis-associated genes in growing human microvascular endothelial cells, thereby suppressing endothelial cell proliferation and migration. Rifampicin, at higher concentrations, also directly inhibited the growth of a variety of human cancer cells. P.o. administration of rifampicin significantly inhibited in vivo growth and metastases of subcutaneous human cancer xenografts. Thus, the potent antiangiogenic properties of oral rifampicin therapy were effective in suppressing cancer progression. It provides a promising new addition to antiangiogenic strategies for designing human cancer therapies. Considering the clinical pharmacokinetics of rifampicin, which enters the enterohepatic circulation and undergoes subsequent hepatic accumulation, it may be especially beneficial as an antitumor agent targeting hepatobiliary tumors.
[Show abstract][Hide abstract] ABSTRACT: Very recently, we reported that an antituberculous agent, rifampicin, exerts potent inhibitory effects on hepatic tumors when administered orally at low doses. The in vitro effects of rifampicin to rapidly downregulate angiogenesis and mitogenesis-related genes in cultured endothelial cells are reminiscent of endostatin, one of the most well-studied angiogenesis inhibitors. However, rifampicin at the expected hepatobiliary concentrations after low oral doses showed more complete antiproliferative effects on endothelial cells, which make rifampicin favorable as an adjunct anticancer regimen. Since rifampicin undergoes hepatic accumulation resulting from the enterohepatic circulation, it may be especially beneficial for targeting hepatobiliary tumors. In the present paper, we extend our observations on the antiangiogenic properties of rifampicin and further elaborate on its direct antitumor effects on a variety of human cancer-derived cells.
[Show abstract][Hide abstract] ABSTRACT: Salusin-alpha and salusin-beta are related bioactive peptides biosynthesized from the same precursor, prosalusin. Despite the potent hemodynamic and proatherosclerotic activities of salusin-beta, its exact distribution and biological functions remain largely undetermined because of technical difficulties associated with its unique physicochemical characteristics, such as marked adhesiveness to polypropylene and polystyrene. By circumventing these problems, we recently established a specific radioimmunoassay for detecting immunoreactive human salusin-beta. In the current study, we demonstrated the release of salusin-beta from the human monoblastic leukemia cell lines, THP-1 and U937. Dilution curves of extracted conditioned media from both cells were parallel with those of standard human salusin-beta by radioimmunoassay. Reverse-phase high performance liquid chromatography coupled with radioimmunoassay detection of the culture supernatants revealed a major immunoreactive component that co-eluted with authentic salusin-beta. Both cell lines secreted salusin-beta-like immunoreactivity (LI) into serum-free media as a function of time (1234.3 + or - 122.7 and 186.7 + or - 9.1 fmol/10(5) cells per 24h). When THP-1 and U937 cells differentiated into macrophages after incubation with 2-O-tetradecanoylphorbol-13-acetate (TPA), they secreted far greater amounts of salusin-beta-LI into the culture supernatant (3351.9 + or - 899.3 and 1545.8 + or - 183.3 fmol/10(5) cells per 24h). TPA treatment accelerated the processing of prosalusin into its cleaved fragments, suggesting that the increased secretion of salusin-beta-LI in THP-1-derived macrophages was caused by the enhanced intracellular processing of prosalusin. Stimulation with the inflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and lipopolysaccharide (LPS), resulted in increased secretion of salusin-beta without inducing expression of the gene for preprosalusin, suggesting that TNF-alpha and LPS stimulated the release of salusin-beta. These data demonstrate that salusin-beta, which induces macrophage foam cell formation, is secreted in its authentic form from human monocytes/macrophages.
[Show abstract][Hide abstract] ABSTRACT: Rifampicin (RFP) is a semisynthetic antibiotic derived from the rifamycins and is one of the most commonly used pharmaceutical compounds worldwide in the treatment of tuberculosis. We previously reported that low-dose and long-term oral administration of RFP to 6 hepatitis C virus-related liver cirrhosis patients who were at high risk for presenting with hepatocellular carcinoma (HCC) resulted in a marked suppression of the occurrence of HCC without showing an adverse effect. The underlying mechanism was found to be due to the anticancer effect based on the potent anti-angiogenic properties of RFP. The present study revealed that RFP has an additional hepatocyte-protective effect by lowering the release of hepatic enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in chronic hepatitis C patients. Experimentally, we were able to show that RFP had hepatocyte-protective effects in acute hepatocyte disorder models of mice and rats induced by concanavalin A and by D-galactosamine, respectively: RFP significantly prevented an increase in the levels of ALT, AST and lactate dehydrogenase in these animal models. In addition, we found that RFP had a strong anti-oxidant action which was approximately three times stronger than the action of silibinin, an anti-inflammatory agent of human hepatic stellate cells, implicating that the hepatocyte-protective effects of RFP are mediated by its anti-oxidant activity. These results reveal that oral administration of RFP exerts not only a prophylactic effect on the occurrence or recurrence of HCC for an extensive period of time, but also exerts hepatocyte-protective effects on both human chronic hepatitis C and acute hepatocyte disorder in rodent models, and the anti-oxidant activity of RFP is implicated to participate in the latter effects.
Experimental and therapeutic medicine 11/2010; 1(6):1041-1047. DOI:10.3892/etm.2010.159 · 1.27 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.