Salvicine

Salvicine, a novel DNA topoisomerase II inhibitor, exerting its effects by trapping enzyme-DNA cleavage complexes.[Pubmed:11551518]

Biochem Pharmacol. 2001 Sep 15;62(6):733-41.

Salvicine, a structurally modified diterpenoid quinone derived from Salvia prionitis, is a novel anticancer drug candidate. The compound has significant in vitro and in vivo activity against malignant tumor cells and xenografts, especially some human solid tumor models. This anticancer activity of Salvicine is associated with its ability to induce tumor cell apoptosis. Salvicine was also found to have a profound cytotoxic effect on multidrug-resistant (MDR) cell lines by down-regulating the expression of MDR-1 mRNA of MDR cells. Salvicine acted as a topoisomerase II (Topo II) poison through its marked enhancement effect on Topo II-mediated DNA double-strand breaks as observed in the DNA cleavage assay. Strong inhibitory activity of Salvicine against Topo II was observed in a kDNA decatenation assay, with an approximate IC(50) value of 3 microM. A similar result was obtained by a Topo II-mediated supercoiled DNA relaxation assay. In contrast, no inhibitory activity was observed against the catalytic activity of Topo I. When the effects of Salvicine on individual steps of the catalytic cycle of Topo II were dissected, it was found that the mechanism by which Salvicine inactivates Topo II is different from that by other anti-Topo II agents. Salvicine greatly promoted Topo II-DNA binding and inhibited pre- and post-strand Topo II-mediated DNA religation without interference with the forward cleavage steps. In addition, Salvicine was not a DNA intercalative agent, as demonstrated by DNA unwinding assays. The results of this study indicate that the inhibitory activity of Salvicine against Topo II was derived from its ability to stabilize DNA strand breaks through interactions with the enzyme alone or with the DNA-enzyme complex. It is therefore postulated that Salvicine acts on Topo by trapping the DNA-Topo II complex, which in turn produces anticancer effects.

Telomerase inhibition is a specific early event in salvicine-treated human lung adenocarcinoma A549 cells.[Pubmed:15369801]

Biochem Biophys Res Commun. 2004 Oct 15;323(2):660-7.

The telomere and telomerase have been suggested as targets for anticancer drug discovery. However, the mechanisms by which conventional anticancer drugs affect these targets are currently unclear. The novel topoisomerase II inhibitor, Salvicine, suppresses telomerase activity in leukemia HL-60 cells. To further determine whether this activity of Salvicine is specific to the hematological tumor and distinct from those of other conventional anticancer agents, we studied its effects on telomere and telomerase in a solid lung carcinoma cell line, A549. Differences in telomerase inhibition and telomere erosion were observed between salvcine and other anticancer agents. All anticancer agents (except adriamycin) induced shortening of the telomere, which was identified independent of replication, but only Salvicine inhibited telomerase activity in A549 cells under conditions of high concentration and short-term exposure. At the low concentration and long-term exposure mode, all the tested anticancer agents shortened the telomere and inhibited telomerase activity in the same cell line. Notably, Salvicine inhibited telomerase activity more severely than the other agents examined. Moreover, the compound inhibited telomerase activity in A549 cells indirectly in a concentration- and time-dependent manner. Salvicine did not affect the expression of hTERT, hTP1, and hTR mRNA in A549 cells following 4 h of exposure. Okadaic acid protected telomerase from inhibition by Salvicine. These results indicate specificity of Salvicine and diversity of anticancer agents in the mechanism of interference with telomerase and the telomere system. Our data should be helpful for designing the study in the development of agents acting on telomere and/or telomerase.

Anti-angiogenic activity of salvicine.[Pubmed:23750780]

Pharm Biol. 2013 Aug;51(8):1061-5.

CONTEXT: Salvicine is a pharmacologically active derivative from Chinese medicinal plant Salvia prionitis Hance (Labiatae). It has been reported that Salvicine inactivates beta1 integrin and inhibits integrin-mediated cell adhesion to fibronectin. Given the emerging correlation between integrins and angiogenesis, we propose that Salvicine abolishes cell adhesion and subsequent metastasis by inhibiting angiogenisis. OBJECTIVE: The anti-angiogenesis activities of Salvicine were investigated for the first time. MATERIALS AND METHODS: The cytotoxicity of Salvicine on human microvascular endothelial cells (HMECs) and non-small cell lung adenocarcinoma A549 cells were measured at doses between 0.625 and 200 microM. Changes of cell migration were detected with doses of Salvicine at 1.25-5 microM, and basement membrane matrigel matrix was used for the assessment of tube formation at concentrations ranging from 0.078 to 1.25 microM. In addition, mRNA expression of basic fibroblast growth factor (bFGF) in A549 cells was studied with the RT-PCR assay. RESULTS: In vitro studies revealed that the IC50 of Salvicine on A549 cells (18.66 microM) was two-fold higher than that of HMECs (7.91 microM). Salvicine (1.25, 2.5 and 5.0 muM) inhibited significantly the endothelial cell migration up to 56, 73 and 82%, respectively. Salvicine decreased capillary-like tube formation of HMECs with high potency. Furthermore, it (30 microM) markedly reduced the mRNA expression of bFGF in A549 cells, while vascular endothelial growth factor (VEGF) mRNA expression remained unchanged. DISCUSSION AND CONCLUSION: Our results suggest that Salvicine has potent anti-angiogenic activity through the inhibition on the sequential angiogenic cascades: proliferation, migration and tube formation and is associated with influence on the expression of bFGF of tumor cell.

Salvicine inactivates beta 1 integrin and inhibits adhesion of MDA-MB-435 cells to fibronectin via reactive oxygen species signaling.[Pubmed:18314480]

Mol Cancer Res. 2008 Feb;6(2):194-204.

Integrin-mediated adhesion to the extracellular matrix plays a fundamental role in tumor metastasis. Salvicine, a novel diterpenoid quinone compound identified as a nonintercalative topoisomerase II poison, possesses a broad range of antitumor and antimetastatic activity. Here, the mechanism underlying the antimetastatic capacity of Salvicine was investigated by exploring the effect of Salvicine on integrin-mediated cell adhesion. Salvicine inhibited the adhesion of human breast cancer MDA-MB-435 cells to fibronectin and collagen without affecting nonspecific adhesion to poly-l-lysine. The fibronectin-dependent formation of focal adhesions and actin stress fibers was also inhibited by Salvicine, leading to a rounded cell morphology. Furthermore, Salvicine down-regulated beta(1) integrin ligand affinity, clustering and signaling via dephosphorylation of focal adhesion kinase and paxillin. Conversely, Salvicine induced extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation. The effect of Salvicine on beta(1) integrin function and cell adhesion was reversed by U0126 and SB203580, inhibitors of MAPK/ERK kinase 1/2 and p38 MAPK, respectively. Salvicine also induced the production of reactive oxygen species (ROS) that was reversed by ROS scavenger N-acetyl-l-cysteine. N-acetyl-l-cysteine additionally reversed the Salvicine-induced activation of ERK and p38 MAPK, thereby maintaining functional beta(1) integrin activity and restoring cell adhesion and spreading. Together, this study reveals that Salvicine activates ERK and p38 MAPK by triggering the generation of ROS, which in turn inhibits beta(1) integrin ligand affinity. These findings contribute to a better understanding of the antimetastatic activity of Salvicine and shed new light on the complex roles of ROS and downstream signaling molecules, particularly p38 MAPK, in the regulation of integrin function and cell adhesion.

Antimetastatic effect of salvicine on human breast cancer MDA-MB-435 orthotopic xenograft is closely related to Rho-dependent pathway.[Pubmed:15867248]

Clin Cancer Res. 2005 May 1;11(9):3455-64.

PURPOSE: Salvicine is a novel DNA topoisomerase II inhibitor with potent anticancer activity. In present study, the effect of Salvicine against metastasis is evaluated using human breast carcinoma orthotopic metastasis model and its mechanism is further investigated both in animal and cellular levels. EXPERIMENTAL DESIGN: The MDA-MB-435 orthotopic xenograft model was applied to detect the antimetastatic effect of Salvicine. Potential target candidates were detected and analyzed by microarray technology. Candidates were verified and explored by reverse transcription-PCR and Western blot. Salvicine activities on stress fiber formation, invasion, and membrane translocation were further investigated by immunofluorescence, invasion, and ultracentrifugal assays. RESULTS: Salvicine significantly reduced the lung metastatic foci of MDA-MB-435 orthotopic xenograft, without affecting primary tumor growth obviously. A comparison of gene expression profiles of primary tumors and lung metastatic focus between Salvicine-treated and untreated groups using the CLOTECH Atlas human Cancer 1.2 cDNA microarray revealed that genes involved in tumor metastasis, particularly those closely related to cell adhesion and motility, were obviously down-regulated, including fibronectin, integrin alpha3, integrin beta3, integrin beta5, FAK, paxillin, and RhoC. Furthermore, Salvicine significantly down-regulated RhoC at both mRNA and protein levels, greatly inhibited stress fiber formation and invasiveness of MDA-MB-435 cells, and markedly blocked translocation of both RhoA and RhoC from cytosol to membrane. CONCLUSION: The unique antimetastatic action of Salvicine, particularly its specific modulation of cell motility in vivo and in vitro, is closely related to Rho-dependent signaling pathway.