The radical scavenger edaravone enhances the anti-tumor effects of CPT-11 in murine colon cancer by increasing apoptosis via inhibition of NF-kappaB.

The transcription factor NF-kappaB is reportedly activated by anti-cancer chemotherapeutic compounds in many cancer cell lines and NF-kappaB activation is one mechanism by which tumors become resistant to apoptosis. Antioxidants have been reported to serve as potent NF-kB inhibitors. In this study, we investigated the ability of edaravone to enhance apoptosis induced by CPT-11 through inhibition of NF-kB. In vitro, SN38, the active metabolite of CPT-11, induced activation of NF-kB, the production of intracellular reactive oxygen species, the activation of caspase-3, and apoptosis in colon26 cells. Pretreatment with edaravone scavenged the SN38-produced reactive oxygen species, and inhibited the SN38-induced activation of NF-kB. Moreover, edaravone enhanced the activation of caspase-3, and the level of apoptosis induced by SN38. In vivo, the combination of edaravone with CPT-11 reduced subcutaneous tumor growth and number of pulmonary metastases more effectively than CPT-11 alone. These results demonstrate that the combination of edaravone with CPT-11 may constitute a new strategy for treating primary and metastatic colon cancer.

Different effects of constitutive nitric oxide synthase and heme oxygenase on pulmonary or liver metastasis of colon cancer in mice.

It has recently been reported that not only endogenous nitric oxide (NO) but also carbon monoxide (CO) produced by heme oxygenase (HO) have many physiological functions. The objective of the present study was to determine whether endogenous NO or CO is involved in the experimental pulmonary or liver metastasis of colon cancer in mice. Intravenous or intrasplenic injection of colon 26 cells from a mouse colon adenocarcinoma cell line resulted in multiple pulmonary or liver metastases. NG-nitro-L-arginine methyl ester (L-NAME), a competitive inhibitor of NO synthase (NOS), or zinc deuteroporphyrin 2, 4-bis glycol (ZnDPBG), a competitive inhibitor of HO, was administered to the mice only on the day of tumor inoculation. We assessed the number of tumor cells 24 h later and the outcome of metastases of the target organ. In the pulmonary metastasis model, L-NAME increased both the number of tumor cells 24 h later and outcome of metastases 18 days later, but did not have a significant effect on liver metastasis. On the other hand, metastasis to the liver, but not that to the lung, increased following administration of ZnDPBG. These results suggest that the activities of NOS and HO could influence experimental metastasis in an organ-specific manner.

Hypoxia-reoxygenation enhances interleukin-8 production from U937 human monocytic cells.

Hypoxia--reoxygenation (H/R) occurs in both inflammatory spots and tumor tissues, sites in which damage is amplified either acutely or chronically through the infiltration of inflammatory cells. Interleukin-8 (IL-8) is a cytokine with chemotactic and angiogenic properties. This study was designed to investigate the effects of H/R on IL-8 production in the U937 human monocytic cell line. Two hours of hypoxia followed by 4 h of reoxygenation induced a significant increase in IL-8 protein production and IL-8 mRNA expression in U937 cells. Pretreatment with proteasome inhibitor (PSI), a peptide aldehyde known to inhibit the chymotrypsin-like activity of the 26S proteasome specifically, suppressed IL-8 protein production and IL-8 mRNA expression induced by H/R. The production of IL-8 protein induced by H/R was decreased by pioglitazone and 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)), which have been identified as peroxisome proliferator-activated receptorgamma (PPAR-gamma) ligands. Moreover, transfection of U937 cells with a dominant negative IkappaBalphaexpression vector (IkappaBalphaM) decreased IL-8 protein production induced by H/R. These results suggest that NF-kappaB and PPAR-gamma regulate H/R-stimulated IL-8 production in U937 cells.

Rotenone, a mitochondrial electron transport inhibitor, ameliorates ischemia-reperfusion-induced intestinal mucosal damage in rats.

In ischemia-reperfusion (I/R)-induced tissue injury, oxygen radicals can be generated by several mechanisms. One of the important sources of oxygen radicals is thought to be mitochondrial respiration. The aim of this study was to investigate the antioxidative defense effect of the mitochondrial electron transport inhibitor, rotenone using the I/R-induced rat intestinal mucosal injury model in vivo. Intestinal ischemia was induced for 30 min by applying a small clamp to the superior mesenteric artery in rats. Rotenone at a dose of 100 mg/kg was given to rats orally 2 h before the ischemia. Intraluminal hemoglobin and protein levels, the mucosal content of thiobarbituric acid-reactive substances (TBARS), the mucosal myeloperoxidase activity, and the content of inflammatory cytokines (CINC-1, TNF-alpha) were all significantly increased from mean basal levels after 60 min of reperfusion. These increases after I/R were inhibited by treatment with rotenone at a dose of 100 mg/kg. Co-administration with succinate (100 mg/kg), a substrate of the mitochondrial electron transport system, cancelled significant reduction of intraluminal hemoglobin and mucosal TBARS treated with rotenone alone. The results of the present study indicate that rotenone inhibited lipid peroxidation and reduced development of the intestinal mucosal inflammation induced by I/R in rats. This investigation suggests that rotenone has potential as a new therapeutic agent for reperfusion injury.

Sterol ferulates, sterols, and 5-alk(en)ylresorcinols from wheat, rye, and corn bran oils and their inhibitory effects on Epstein-Barr virus activation.

Sterol ferulate, free sterol, and 5-alk(en)ylresorcinol constituents of wheat, rye, and corn bran oils were studied. Among the sterol ferulates, one novel compound, 24-methylenecholestanol ferulate (7), along with six known compounds, namely, 24-methylcholestanol ferulate (1), 24-methylcholesterol ferulate (2), 2-methyllathosterol ferulate (3), stigmastanol ferulate (4), sitosterol ferulate (5), and schottenol ferulate (6), were isolated and characterized. Five known free sterols, namely, 24-methylcholesterol (8), stigmastanol (9), sitosterol (10), schottenol (11), and stigmasterol (12), were isolated and identified. 5-Alk(en)ylresorcinols were found in wheat and rye bran oils but not in corn bran oil. Of these, one new compound, 5-n-(2'-oxo-14'-Z-heneicosenyl) resorcinol (19), and seven known compounds, namely, 5-n-heptadecyl- (13), 5-n-nonadecyl- (14), 5-n-heneicosyl- (15), 5-n-tricosyl- (16), 5-n-pentacosyl- (17), 5-n-(14'-Z-nonadecenyl)- (18), and 5-n-(2'-oxoheneicosyl)resorcinols (20), were isolated and characterized. These compounds were evaluated with respect to their inhibitory effects on the induction of Epstein-Barr virus early antigen (EBV-EA) by 12-O-tetradecanoylphorbol-13-acetate (TPA) in Raji cells, which is known to be a primary screening test for antitumor promoters. Four compounds, 1, 2, 4, and 11, showed potent inhibitory effects on EBV-EA induction.

Interleukin-10 plasmid DNA inhibits subcutaneous tumor growth of Colon 26 adenocarcinoma in mice.

The transcription factor NF-kappa B is constitutively activated in many human cancers, and induces the expression of multiple proteins including antiapoptotic proteins. Recent papers indicate that NF-kappa B activation is inhibited by interleukin (IL)-10. In this study, we investigated the effect of IL-10 plasmid DNA on colon cancer in mice. In vitro study: Colon 26 murine colon adenocarcinoma cells were either treated or untreated with IL-10 for 60 min. The cells were subsequently stimulated with TNF-alpha. In vivo study: to induce a high level of IL-10 in plasma, we transferred the naked plasmid vectors encoding the mouse IL-10 gene into the liver via the intravenous route. To establish tumors, we injected Colon 26 cells into BALB/c mice subcutaneously. In vitro study: a 24-h incubation with TNF-alpha did not affect cell viabilities; however, pretreatment with IL-10 significantly enhanced the level of apoptosis induced by TNF-alpha. Pretreating Colon 26 cells with IL-10 significantly attenuated the TNF-alpha-induced NF-kappa B activation. In vivo study: IL-10 plasmid controlled the growth of subcutaneous tumors. In subcutaneous tumor, NF-kappa B was activated in response to tumor growth. IL-10 plasmid markedly inhibited this activation of NF-kappa B in subcutaneous tumor. IL-10 plasmid induced cancer cell apoptosis linked to the down-regulation of antiapoptotic proteins, and the activation of caspase-3. These results demonstrate that IL-10 plasmid may constitute a new strategy for treating cancer growth.

New cinnamylphenols from Dalbergia species with cancer chemopreventive activity.

Five new cinnamylphenols (1,3-diphenylpropenes), dalberatins A (1), B (2), C (3), D (4), and E (5), were isolated from plants of the Dalbergia species. They were characterized and tested for their inhibitory activities against Epstein-Barr virus early antigen activation induced by 12-O-tetradecanoylphorbol-13-acetate in Raji cells. The cinnamylphenols were found to show remarkably potent activities. The result of the present investigation indicated that some of these cinnamylphenols might be valuable as potential cancer chemopreventive agents (anti-tumor promoters).

Ichthyotoxic and anticarcinogenic effects of triterpenoids from Sandoricum koetjape bark.

After bioassay-guided fractionation of the extract from Sandoricum koetjape bark, which exhibited significant toxicity to killifish (Oryzias latipes), two ichthyotoxic triterpenoids were isolated and characterized as koetjapic acid and 3-oxo-olean-12-en-29-oic acid. These constituents, along with non-toxic katonic acid, had a remarkable inhibitory effect on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA), which is a preliminary in vitro screening method for possible anti-tumor-promoting agents. Of the triterpenoids active in vitro, koetjapic acid appears to be a promising cancer chemopreventive agent, since it significantly delayed tumor promotion in two-stage mouse skin carcinogenesis induced by 7,12-dimethylbenz(a)anthracene and promoted by TPA.

Triterpene acids from the leaves of Perilla frutescens and their anti-inflammatory and antitumor-promoting effects.

Nine triterpene acids, viz., six of the ursane type, ursolic acid (1), corosolic acid (2), 3-epicorosolic acid (3), pomolic acid (4), tormentic acid (5) and hyptadienic acid (6), and three of the oleanane type, oleanolic acid (7), augustic acid (8) and 3-epimaslinic acid (9), among which 1 constituted the most predominant triterpene acid, were isolated and identified from ethanol extracts of the leaves of red perilla [Perilla frutescens (L.) Britton var. acuta Kudo] and green perilla [P. frutescens (L.) Britton var. acuta Kudo forma viridis Makino]. These eight compounds, 1, 2, 4-9, were evaluated for their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation (1 microg/ear) in mice. All the compounds tested showed a marked anti-inflammatory effect, with a 50% inhibitory dose (ID50) of 0.09-0.3 mg per ear. In addition, an evaluation against the Epstein-Barr virus early antigen (EBV-EA) activation induced by TPA showed five compounds, 1-3, 5 and 9, with a potent inhibitory effect on EBV-EA induction (91-93% inhibition at 1x10(3) mol ratio/TPA). Furthermore, compound 5 exhibited strong antitumor-promoting activity in an in vivo two-stage carcinogenesis test of mouse tumor by using 7,12-dimethylbenz(a)anthracene (DMBA) as an initiator and TPA as a promoter.