FR901228, a novel antitumor bicyclic depsipeptide produced by Chromobacterium violaceum No. 968. III. Antitumor activities on experimental tumors in mice

The antitumor activities of FR901228, (E)-(1S,4S,10S,21R)-7-[(Z)- ethylidene]-4,21-diisopropyl-2-oxa-12,13-dithia-5,8,20,23- tetraazabicyclo[8,7,6]-tricos-16-ene-3,6,9,19,22-pentanone, isolated from Chromobacterium violaceum No. 968, were studied in animals. FR901228 (ip) prolonged the life of mice bearing such murine ascitic tumors as P388 and L1210 leukemias and B16 melanoma, and inhibited (iv) the growth of murine solid tumors (Colon 38 carcinoma, M5076 reticulum cell sarcoma and Meth A fibrosarcoma) and human solid tumors (Lu-65 and LC-6 lung carcinomas, and SC-6 stomach adenocarcinoma) implanted in normal and nude mice, respectively. Its antitumor activity was especially potent against murine Meth A fibrosarcoma and human SC-6 stomach adenocarcinoma which were refractory to mitomycin C or cisplatin. FR901228 also was more effective against mitomycin C-, cyclophosphamide-, vincristine- and 5-fluorouracil-resistant P388 leukemias than against non-resistant P388 in mice. These results suggest that FR901228 will be a new type of drug for the treatment of cancer.

New antitumor substances, FR901463, FR901464 and FR901465. II. Activities against experimental tumors in mice and mechanism of action

FR901463, FR901464 and FR901465, novel antitumor substances, were isolated from the fermentation broth of Pseudomonas sp. No. 2663. Their antitumor activities were examined in three mouse tumor systems and one human tumor system. The three FR compounds prolonged the life of mice bearing murine ascitic tumor P388 leukemia (T/C values were 160%, 145% and 127% for FR901463, FR901464 and FR901465, respectively), and inhibited the growth of a human solid tumor, A549 lung adenocarcinoma, with different effective dose ranges. FR901464 exhibited most prominent effects on these tumor systems among the three FR compounds. FR901464 also inhibited the growth of murine solid tumors, Colon 38 carcinoma and Meth A fibrosarcoma. To address the involvement of transcriptional activation ability of the three FR compounds in the antitumor effect, we selected FR901464 as a candidate compound and investigated cell cycle transition, chromatin status and endogenous gene expression in FR901464-treated tumor cells having elevated transcriptional activity. FR901464 induced characteristic G1 and G2/M phase arrest in the cell cycle and internucleosomal degradation of genomic DNA with the same kinetics as activation of SV40 promoter-dependent cellular transcription in M-8 tumor cells. In contrast to the potent activation of the viral promoter, FR901464 suppressed the transcription of some inducible endogenous genes but not house keeping genes in M-8 cells. These results suggest that FR901464 may induce a dynamic change of chromatin structure, giving rise to strong antitumor activity, and therefore may represent a new type of drug for cancer chemotherapy.

Intratumoral injection of oligonucleotides to the NF kappa B binding site inhibits cachexia in a mouse tumor model

Cancer cachexia, characterized by anorexia, weight loss and progressive tissue wasting, has been postulated to be mediated by various cytokines. However, the precise mechanism of cachexia induction is not fully explained. We have developed synthetic double-stranded oligodeoxynucleotides (ODN) as 'decoy' cis-elements that block the binding of nuclear factors to promoter regions of targeted genes, resulting in the inhibition of gene transactivation in vivo as well as in vitro. This novel molecular strategy could be useful for treating a broad range of human diseases including cancer. In this study, we injected decoy ODN targeting the transcriptional factor, NF-kappa B (NF kappa B) binding cis-elements, which are essential for transactivation of gene expression of cytokines, directly into tumors of adenocarcinoma colon26 in mice, in order to examine whether or not cachexia is alleviated by inhibiting the action of cytokines. Tumor growth was not affected by transfection of NF kappa B decoy ODN as compared with scrambled decoy ODN. Nevertheless, transfection of NF kappa B decoy, but not scrambled decoy, ODN resulted in attenuation of the reductions in body weight, epididymal fat, gastrocnemius muscle mass and food intake, which were induced by the tumor presence. Interleukin 6 mRNA in the tumor was also markedly decreased by the transfection of NF kappa B decoy ODN. It is known that the transcriptional factor E2F plays a pivotal role in the coordinated transactivation of cell cycle regulatory genes. Therefore, we hypothesized that the introduction of synthetic double-stranded DNA with high affinity for E2F in vivo as 'decoy' cis-elements might inhibit the tumor growth of colon26, resulting in turn in inhibition of cachexia induction. However, injection of E2F decoy ODN failed to inhibit tumor growth and cachexia induction, as compared with mismatched decoy ODN. Overall, the present study demonstrated that cachexia induced by adenocarcinoma colon26 was inhibited by blocking of NF kappa B, using a novel molecular decoy strategy, without an effect on tumor growth, and also that tumor growth and cachexia induction in the colon26 model were not affected by E2F decoy ODN. These results suggest that cytokines regulated by NF kappa B may play a pivotal role in the induction of cachexia by colon26, providing a new therapeutic strategy for cancer cachexia.

Recombinant human tumor necrosis factor-alpha: thrombus formation is a cause of anti-tumor activity

In a previous study we showed that recombinant human tumor necrosis factor-alpha (rTNF-alpha) has no cytolytic effect on Meth A fibrosarcoma cells in vitro but that it has a strong anti-tumor activity in vivo. In the present work, we define the in vivo mode of action of rTNF-alpha on solid-form Meth A fibrosarcoma implanted intradermally (i.d.) in mice. rTNF-alpha exhibited strong anti-tumor activity when given intravenously (i.v.) 7 or 10 days after tumor implantation, but not when given 3 days after implantation. Light and electron microscopy showed that rTNF-alpha impaired microcirculation by producing fibrin-like substances in newly formed microcapillaries in 7-day-old tumor tissue. An anti-coagulant, dicoumarol, abrogated the effect of rTNF-alpha. Injection of carbon particles showed that the development of capillaries in 7-day-old tumors was more extensive than in 3-day-old tumors, and suggested that the anti-tumor activity of rTNF-alpha depends upon a fully developed fine network of induced capillaries in the tumor. Electron microscopy showed that rTNF-alpha increases the number of primary and secondary lysosomes in the cytoplasm of 7-day-old tumor cells. The results suggest that rTNF-alpha selectively stems the blood flow in newly formed microcapillaries, eventually leading to autolysis of the tumor cells.

Effects of FK228, a novel histone deacetylase inhibitor, on human lymphoma U-937 cells in vitro and in vivo

FK228 [(E)-(1S,4S,10S,21R)-7-[(Z)-ethylidene]-4,21-diisopropyl-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo-[8,7,6]-tricos-16-ene-3,6,9,19,22-pentanone; FR901228, depsipeptide] is a novel histone deacetylase inhibitor that shows therapeutic efficacy in Phase I trials of patients with malignant lymphoma. However, its mechanism of action has not been characterized. In this study, we examined the in vitro and in vivo effects of FK228 on human lymphoma U-937 cells. FK228 very strongly inhibited the growth of U-937 cells with an IC(50) value of 5.92 nM. In a scid mouse lymphoma model, mice treated with FK228 once or twice a week survived longer than control mice, with median survival times of 30.5 (0.56 mg/kg) and 33 days (0.32 mg/kg), respectively (vs. 20 days in control mice). Remarkably, 2 out of 12 mice treated with FK228 (0.56 mg/kg once or twice a week) survived past the observation period of 60 days. The apoptotic population of U-937 cells time-dependently increased to 37.7% after 48 hr of treatment with FK228. In addition, FK228 induced G1 and G2/M arrest and the differentiation of U-937 cells to the CD11b(+)/CD14(+) phenotype. Expression of p21(WAF1/Cip1) and gelsolin mRNA increased up to 654- and 152-fold, respectively, after 24hr of treatment with FK228. FK228 caused histone acetylation in p21(WAF1/Cip1) promoter regions, including the Sp1-binding sites. In conclusion, (i) FK228 prolonged the survival time of scid mice in a lymphoma model, and (ii) the beneficial effects of FK228 on human lymphoma may be exerted through the induction of apoptosis, cell cycle arrest, and differentiation via the modulation of gene expression by histone acetylation.

Antitumor efficacy of FK228, a novel histone deacetylase inhibitor, depends on the effect on expression of angiogenesis factors

It has been recently demonstrated that histone deacetylase inhibitors inhibit angiogenesis, but their mechanism of action has not been characterized well. In this study, we examined the in vitro and in vivo effects of FK228 [(E)-(1S,4S,10S,21R)-7-[(Z)-ethylidene]-4,21-diisopropyl-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo-[8,7,6]-tricos-16-ene-3,6,9,19,22-pentanone; FR901228, depsipeptide], an HDAC inhibitor, on the expression of angiogenesis factors in FK228-sensitive PC-3 prostate and FK228-resistant ACHN renal cancer cells. FK228 suppressed the expression of VEGF mRNA in PC-3 cells, but not in ACHN cells. FK228 also suppressed the expression of basic fibroblast growth factor (bFGF) mRNA in both PC-3 and ACHN cells. Under conditions of hypoxia, FK228 suppressed the expression of VEGF mRNA without modulating the expression of hypoxia-inducible factor-1 alpha mRNA in PC-3 cells. FK228 induced the highest acetylation of histone H3 and H4 in the P2 region of the VEGF promoter, which includes the hypoxia-inducible factor-1 alpha binding site that plays an important role in regulating the expression of VEGF gene. Moreover, FK228 reduced the amount of VEGF and bFGF protein, and their mRNA levels in PC-3 xenograft implanted in nude mice, but did not reduce them in ACHN xenograft.

IN CONCLUSION

(i) FK228 showed a suppressive effect on the expression of angiogenesis factors, such as VEGF and bFGF, in PC-3 xenograft but not in ACHN xenograft, which suggests that the effect on the expression of angiogenesis factors is important for the antitumor efficacy of FK228; (ii) FK228 caused histone acetylation of the VEGF promoter regions, which may contribute to the suppression of VEGF gene expression.

Marker genes to predict sensitivity to FK228, a histone deacetylase inhibitor

In this study, we detected genes sensitive to an histone deacetylase inhibitor, FK228 [(E)-(1S,4S,10S,21R)-7-[(Z)-ethylidene]-4,21-diisopropyl-2-oxa-12,13-dithia-5,8,20,23-tetraazabicyclo-[8,7,6]-tricos-16-ene-3,6,9,19,22-pentanone; FR901228, depsipeptide] in vitro and identified marker genes to predict sensitivity to FK228 in vivo using Affymetrix GeneChip. Three percent of genes (205/7070) were sensitive to FK228 in vitro, 105 and 100 genes, were up- and down-regulated, respectively, by FK228. Commonly up-regulated genes included p21(WAF1/Cip1), interleukin-8 (IL-8), histone family, JunB, caspase 9, mitogen-activated protein kinase phosphatase 1 (MKP-1) and mitogen-activated protein kinase (MAPK) family, and commonly down-regulated genes included cyclin A and MAPK family. One percent of genes (76/7070) showed native differences in patterns of expression, when FK228-sensitive (PC-3 prostate and SC-6-JCK (SC-6) stomach) and FK228-resistant (ACHN and A-498 renal) tumors implanted in BALB/c nu/nu mice were compared. Twenty-seven and forty nine of those genes were expressed at high or low levels, respectively, in FK228-sensitive tumors. Caspase 9 and MKP-1 genes showed distinct differences in patterns of expression between FK228-sensitive and resistant tumors and have been known to have roles in apoptosis and chromatin remodeling. The expression of caspase 9 gene was higher in FK228-sensitive tumors and the expression of MKP-1 gene was higher in FK228-resistant tumors. Caspase 9 and MKP-1 genes in the other FK228-sensitive tumors had the same patterns of expression as they did in PC-3 and SC-6 tumors. Our results present profiles of gene expression related to FK228 and marker genes to predict sensitivity to FK228, such as caspase 9 and MKP-1 genes.

Intravenous injection of oligodeoxynucleotides to the NF-kappaB binding site inhibits hepatic metastasis of M5076 reticulosarcoma in mice

We have developed synthetic double-stranded oligodeoxynucleotides (ODN) as 'decoy' cis elements that block the binding of nuclear factors to promoter regions of targeted genes, resulting in the inhibition of gene transactivation in vivo. In the present study, we employed decoy ODN targeting the transcription factor nuclear factor-kappaB (NF-kappaB) binding cis-elements to hepatic metastasis of murine reticulosarcoma M5076 in mice. Intravenous inoculation of M5076 into mice caused a marked increase in gene expression of interleukin-1beta, tumor necrosis factor-alpha and intercellular adhesion molecule-1 in the liver, whereas intravenous treatment with NF-kappaB decoy ODN reduced M5076-induced transactivation of these genes. Treatment with NF-kappaB decoy ODN, but not scrambled decoy ODN, significantly inhibited hepatic metastasis of M5076 in mice, and furthermore the combined treatment of NF-kappaB decoy ODN with an anti-cancer drug resulted in complete inhibition of hepatic metastasis in half of the mice, without affecting myelosuppression induced by the anti-cancer drug. Here, NF-kappaB decoy ODN inhibited hepatic metastasis of M5076 in mice possibly through a decrease in transactivation of important NF-kappaB-driven genes and also potentiated the anti-metastatic effect of an anti-cancer drug, demonstrating the first successful in vivo therapy for cancer metastasis using NF-kappaB decoy ODN as a novel molecular decoy approach.

FK317: a novel substituted dihydrobenzoxazine with potent antitumor activity which does not induce vascular leak syndrome

PURPOSE

FK973, a substituted dihydrobenzoxazine, is an antitumor antibiotic which has shown high therapeutic efficacy in a phase I study, but its development has been abandoned because of the side effect of vascular leak syndrome (VLS) in the clinical study. This study was performed to investigate whether or not FK317, a new benzmethoxy derivative of FK973, retains the antitumor activity of FK973 without the side effect of VLS.

METHODS

VLS was evaluated by the volume of pleural effusion in rats. Cytotoxic activities were determined by a tetrazolium-based colorimetric assay (MTT assay) against murine (B16, P388) and human (HeLa S3, KB) tumor cell lines. Antitumor activities against murine ascitic leukemia (P388, L1210), murine solid tumors (reticulum cell sarcoma M5076, Colon 38 carcinoma) and human xenografts (mammary carcinoma MX-1, lung carcinoma LX-1) were examined.

RESULTS

FK973 (1.8 mg/kg) given i.v. to rats induced pleural effusion, one of the elements of VLS, 36 days after the first dosing, but did not 28 days after dosing. This model reflects clinical VLS delayed-type effusion with high protein concentrations. In contrast, FK317 (1.0-3.2 mg/kg) did not induce pleural effusion at all. FK317 had stronger cytotoxic effects against in vitro cultured B16, P388, HeLa S3 and KB tumor cell lines, and in in vivo experiments, FK317 showed equivalent antitumor activity against P388, M5076 and MX-1, and more potent antitumor activity against L1210, Colon 38 and LX-1 compared with FK973.

CONCLUSION

These results suggest that FK317 retains the antitumor activity of FK973 and does not induce VLS, and FK317 is a drug with high clinical potential for treating tumors in humans.

Effects of FK228, a novel histone deacetylase inhibitor, on tumor growth and expression of p21 and c-myc genes in vivo

In this study, we examined the effects of FK228 (FR901228, depsipeptide) on tumor growth and expression of p21 and c-myc genes in vivo. FK228 induced the expression of p21 mRNA and decreased c-myc mRNA in tumor xenograft sensitive to FK228. However, FK228 did not sufficiently modulate the expression of p21 mRNA and increased the expression of c-myc in tumor xenograft less sensitive to FK228. The modulation of p21 and/or c-myc genes may be critical for the marked antitumor activity of FK228 in vivo.

Mechanism by which a novel non-thiazolidinedione peroxisome proliferator-activated receptor gamma agonist, FK614, ameliorates insulin resistance in Zucker fatty rats

AIM

The aim of this study was to examine the mechanism by which a novel non-thiazolidinedione (TZD) peroxisome proliferator-activated receptor (PPAR) gamma agonist, FK614, ameliorates insulin resistance in Zucker fatty rats.

METHODS

FK614 (1, 3.2 or 10 mg/kg) and a TZD PPARgamma agonist, pioglitazone (1, 3.2 or 10 mg/kg), were orally administered to Zucker fatty rats (genetically obese and insulin resistant) once a day for 14 days, and an oral glucose tolerance test was performed. The expression levels of various genes in the white adipose tissue (WAT) of Zucker fatty rats treated with FK614 (3.2 mg/kg), pioglitazone (10 mg/kg) and another TZD PPARgamma agonist, rosiglitazone (3.2 mg/kg), were determined using a real-time reverse transcription-polymerase chain reaction method. Morphometric analysis of the WAT of Zucker fatty rats treated with FK614 (3.2 mg/kg) and pioglitazone (10 mg/kg) was performed. Glucose transport activity in the isolated soleus muscle of FK614-treated Zucker fatty rats was also investigated.

RESULTS

FK614 and pioglitazone both improved glucose tolerance in Zucker fatty rats. FK614 significantly increased the expression levels of acyl CoA oxidase, a PPAR-responsive gene, and adipocyte fatty acid-binding protein (aP2), an adipocyte differentiation marker gene, in epididymal WAT. It also significantly decreased the level of gene expression of tumour necrosis factor-alpha, an insulin resistance-inducing factor in retroperitoneal WAT, as did pioglitazone and rosiglitazone. FK614 and pioglitazone both significantly increased the total number of adipocytes and decreased their average size in WAT, mainly by increasing the number of small adipocytes. Additionally, administration of FK614 to Zucker fatty rats enhanced insulin sensitivity for glucose uptake in the soleus muscle.

CONCLUSION

This study suggests the possibility that FK614 induces adipocyte differentiation in Zucker fatty rats by stimulating PPARgammain vivo, thereby changing the character of WAT and improving insulin sensitivity throughout the body.

Ameliorating effect of FK614, a novel nonthiazolidinedione peroxisome proliferator-activated receptor γ agonist, on insulin resistance in Zucker fatty rat

Effect of 3-(2,4-dichlorobenzyl)-2-methyl-N-(pentylsulfonyl)-3H-benzimidazole-5-carboxamide (FK614), a novel nonthiazolidinedione peroxisome proliferator-activated receptor (PPAR) gamma agonist, on glucose tolerance and insulin resistance in peripheral tissues and in liver using Zucker fatty rats (genetically obese and insulin-resistant) was evaluated and compared to other insulin sensitizers. FK614 (0.32, 1 and 3.2 mg/kg), two thiazolidinedione PPAR gamma agonists, rosiglitazone (0.1, 0.32, 1 and 3.2 mg/kg) and pioglitazone (1, 3.2 and 10 mg/kg), and a biguanide, metformin (320 and 1000 mg/kg), were orally administered to Zucker fatty rats once a day for 14 days. Zucker fatty rats treated with FK614 and rosiglitazone were subjected to evaluation by oral glucose tolerance test. Ameliorating effect of each compound on peripheral and hepatic insulin resistance was evaluated using a euglycemic-hyperinsulineamic clamp procedure. FK614 and rosiglitazone dose-dependently improved impaired glucose tolerance in Zucker fatty rats. In addition, FK614 dose-dependently ameliorated peripheral and hepatic insulin resistance in Zucker fatty rats, with the degree of its effect in peripheral tissues almost equivalent to that in liver when compared at each dose tested. Similar data indicating ameliorating effects on insulin resistance was obtained for rosiglitazone and pioglitazone. Metformin showed less potent effects than other insulin sensitizers and its effect in liver tended to be greater than that in peripheral tissues. These findings suggest clinical potential for FK614 as a treatment of type 2 diabetes, acting by ameliorating insulin resistance both in peripheral tissues and liver.

Cytotoxic mechanisms of FK317, a new class of bioreductive agent with potent antitumor activity

FK317 is a member of a new class of bioreductive agents that exhibit strong cytotoxicity against various human cancer cells. The effect of FK317 was found to be stronger than that of mitomycin C (MMC), adriamycin (ADR) or cisplatin (CDDP). Alkaline elution analysis indicated that FK317 formed interstrand DNA-DNA and DNA-protein cross-links in cells. On the other hand, no DNA single-strand breaks were observed in the cells treated with FK317. In a cell-free system the deacetylated metabolites produced cross-linked DNA under reductive conditions, though FK317 itself did not form DNA-DNA cross-links. In order to elucidate the metabolic activation mechanisms, we established an FK317-resistant subline from human non-small cell lung cancer cells (Lu99) by stepwise and brief exposure (1 h) to FK317. The resistant subline (Lu99/317) showed cross-resistance to MMC and carboquone (CQ), but not to ADR or CDDP. DT-diaphorase, which is one of the activation enzymes of MMC and CQ, was deficient in Lu99/317 cells as determined by enzyme activity assay. However, the levels of NADPH:cytochrome P450 reductase, which is another activation enzyme for MMC and CQ, were comparable in resistant and parent cell lines. Treatment of the cells with dicumarol, an inhibitor of DT-diaphorase, reduced the cytotoxicity of FK317 to Lu99 cells, but not to Lu99/317 cells. These results indicate that deacetylation of FK317 is necessary for its reductive activation, and deacetylated FK317 is reduced by DT-diaphorase to form an active metabolite, which produces DNA-DNA interstrand and DNA-protein cross-links that lead to cell death.

Resiniferatoxin antagonizes cisplatin-induced emesis in dogs and ferrets

We evaluated the antiemetic activity of resiniferatoxin, an ultrapotent capsaicin analogue, on cisplatin- and apomorphine-induced emesis in dogs, and on cisplatin-induced acute and delayed emesis in ferrets. In the dog, resiniferatoxin (10 microg/kg, s.c.) 30 min before the injection of cisplatin markedly prevented acute emesis induced by cisplatin. When animals were given resiniferatoxin (10 microg/kg, s.c.) 24 h prior to cisplatin, the emesis was still inhibited, but not significantly. Resiniferatoxin (10 microg/kg, s.c.) 30 min before the administration of apomorphine also significantly reduced the emetic responses induced by apomorphine in dogs. In the ferret, resiniferatoxin (10 microg/kg, s.c.) 30 min prior to cisplatin completely inhibited acute emesis caused by cisplatin (10 mg/kg, i.p.). When ferrets were given resiniferatoxin (10 microg/kg, s.c.) 16 h prior to cisplatin, the emesis was still significantly inhibited. Cisplatin (5 mg/kg, i.p.) induced both acute (0-24 h) and delayed (24-72 h) phase emesis, and a single injection of resiniferatoxin (10 microg/kg, s.c.) at 36 h after cisplatin significantly reduced subsequent emetic responses during the 36-72 h period. These results suggest that resiniferatoxin-related vanilloids may be useful drugs against both acute and delayed emesis induced by cancer chemotherapy.

FK317, a novel substituted dihydrobenzoxazine, exhibits potent antitumor activity against human tumor xenografts in nude mice

The antitumor effects of FK317, a novel substituted dihydrobenzoxazine, were evaluated using human tumor xenografts (small cell lung cancer, non-small cell lung cancer, stomach cancer, colon cancer, pancreatic cancer, breast cancer, cervical cancer and ovarian cancer). Tumor growth-inhibitory effects and the effective dose-range of FK317 were much stronger and broader, respectively, than those of reference drugs such as mitomycin C, adriamycin, cisplatin, taxol and irinotecan. Furthermore, the body weight decrease and myelosuppression in FK317-treated mice were less than in the animals given any of the reference drugs. To explain this tumor selectivity, the distribution of FK317 was investigated after dosing tumor-bearing mice with the 14C-labelled compound. The concentration of FK317 in tumor tissues was relatively low, and long tumor retention was not observed. However, thin-layer chromatographic separation revealed that the radioactivity in the tumor resided mainly in strongly cytotoxic metabolites, while that in other tissues resided mainly in non-cytotoxic metabolites. These results suggest that FK317 shows strong antitumor activity without side effects, and one reason for this is its specific metabolite pattern. FK317 is now undergoing phase I clinical trials.

Anti-cachectic effect of FK317, a novel anti-cancer agent, in colon26 and LX-1 models in mice

The effects of FK317 (11-acetyl-8-carbamoyloxymethyl-4-formyl-6- methoxy-14-oxa-1,11-diazatetracyclo[7.4.1.0(2, 7). 0(10, 2] tetradeca-2,4,6-trien-9-yl acetate), a novel anti-cancer agent, on murine adenocarcinoma colon26- and human lung carcinoma LX-1-induced cachexia were investigated in mice. Mice bearing colon26 or LX-1 s.c. lost weight and became cachectic, associated with tumor growth. FK317 and mitomycin C (MMC) inhibited the growth of both tumors. FK317 ameliorated the weight loss induced by the presence of colon26 or LX-1, while MMC enhanced it. An attenuation of the reduction in the weights of epididymal fat, gastrocnemius muscle and carcass was observed in FK317-treated tumor-bearing mice in both cachexia models, but not in MMC-treated mice. The decreases in the circulating levels of triglyceride, glucose and non-esterified fatty acid, which were induced by the presence of colon26, was partially inhibited by treatment with FK317. Overall, this study revealed that FK317 is a potent anti-cancer drug with anti-cachectic activity, suggesting that FK317 has potential utility for the treatment of cancer.

Effect of FK973, a new antitumor antibiotic, on the cell cycle of L1210 cells in vitro

Our previous study showed that FK973 (11-acetyl-8-carbamoyloxymethyl-4-formyl-14-oxa-1,11- diazatetracyclo[7.4.1.0(2,7)0(10,12)]tetradeca-2,4,6-trien-6 ,9-diyl diacetate), a novel substituted dihydrobenzoxazine, which is a derivative of the fermentation product of Streptomyces sandaensis No. 6897, had strong antitumor effects on experimental tumors in vitro and in vivo. In this report, we investigated its effect on the cell cycle of murine leukemia L1210 cells in vitro by means of DNA/5-bromo-2'-deoxyuridine double staining and compared these effects with those of other antitumor drugs. Both FK973 and mitomycin C arrested the cells in the G2 phase. Vinblastine arrested the cells in the M phase and cytosine arabinoside, in the G1 phase. Although FK973 and mitomycin C were shown to act on the cell cycle in a similar way, FK973 was slower in producing its effect. From the results, FK973 arrests the cells in the G2 phase, and it appears that FK973 must be converted into the activated form in the cells for the development of its antitumor effects.

Different effects of FK317 on multidrug-resistant tumor in vivo and in vitro

FK317, a novel substituted dihydrobenzoxazine, was examined for antitumor effects on multidrug-resistant (MDR) tumor cells in vitro and in vivo. In nude mice, FK317 markedly inhibited the growth of s.c. implanted KB-V1 vinblastine (VLB)-resistant human epidermal carcinoma KB cells, as well as the parent cells (KB-3-1). However, KB-V1 showed much greater resistance to FK317 than to VLB and adriamycin (ADM) in the in vitro study. This resistance was reversed by the addition of verapamil, whereby intracellular accumulation of FK317 in the KB-V1 cells was also decreased. After incubation of FK317 in human and mouse blood, it was shown to be rapidly metabolized to a monodeacetylated form, and slowly metabolized further to a dideacetylated form. With the removal of the acetyl groups from FK317, resistance indexes in KB-V1 and SBC-3/ADM, ADM-resistant human lung carcinoma, decreased. In addition, photolabeling of P-glycoprotein with [3H]azidopine in KB-V1 plasma membrane was completely inhibited by FK317, but not by the deacetylated metabolites. These results indicate that FK317 is metabolized to deacetylated forms, which do not bind to P-glycoprotein and are incorporated into MDR cells, causing cytotoxic effects.

Acute and chronic effects of FR-149175, a beta 3-adrenergic receptor agonist, on energy expenditure in Zucker fatty rats

Clinical therapies for both obesity and obese non-insulin-dependent diabetes mellitus require maintenance of reduced body weight after the initial successful reduction resulting from calorie control, exercise, or medication. Although beta(3)-adrenergic receptor (beta(3)-AR) agonists have been shown to stimulate whole body energy expenditure and lipid mobilization, whether stimulatory effects on oxygen consumption and lipolysis are influenced by chronic exposure to agonists has not been fully characterized. We therefore examined the acute and chronic effects of FR-149175, a selective beta(3)-AR agonist, on whole body oxygen consumption in genetically obese Zucker fatty rats. Chronic treatment with FR-149175 caused a decrease in both body weight gain and white fat pad weight at doses that induced lipolysis in acute treatment (1 and 3.2 mg/kg p.o.). Single administration of FR-149175 (0.1, 1, and 3.2 mg/kg p.o.) dose dependently increased whole body oxygen consumption. Repetitive administration did not cause attenuation of the thermogenic response at lower doses (0.1 and 1 mg/kg 2 times daily), whereas the highest dose (3.2 mg/kg 2 times daily) induced a progressive increase in oxygen consumption. PCR analyses of retroperitoneal white adipose tissue indicated little or no change in beta(3)-AR mRNA levels. Uncoupling protein 1 gene expression increased at 1 mg/kg, and drastic upregulation was detected at 3.2 mg/kg. FR-149175 also increased HSL mRNA levels in a dose-related manner, whereas there was no effect on genes involved in beta-oxidation. These results support that the thermogenic effect of beta(3)-AR agonists is not attenuated by chronic exposure to agonists.

Effects of FK317, a novel anti-cancer agent, on survival of mice bearing B16BL6 melanoma and Lewis lung carcinoma

The effects of FK317 (11-acetyl-8-carbamoyloxymethyl-4-formyl-6-methoxy-14- oxa-1,11-diazatraacylo[7.4.1.0(2.7).0(10.2)]-tetradeca-2,4,6-trien-9-yl acetate), a novel anti-cancer agent, and mitomycin C (MMC) on survival time of mice bearing B16BL6 melanoma and Lewis lung carcinoma (LLC), induced by intravenous inoculation of the tumor, were investigated. Treatment with FK317 resulted in a significant prolongation of survival time in both tumor models. Four of ten mice bearing B16BL6 were disease-free following FK317 treatment. In contrast, MMC was not effective in prolonging survival time. Overall, this study demonstrated that FK317 shows more potent survival extension in mice bearing B16BL6 and LLC than MMC, suggesting that FK317 may have therapeutic utility for cancer chemotherapy.

The efficacy of combined treatment with recombinant human tumor necrosis factor-alpha and 5-fluorouracil is dependent on the development of capillaries in tumor

The antitumor effects of recombinant human tumor necrosis factor-alpha (rTNF-alpha) and 5-fluorouracil (5-FU) in combination treatment were examined on Meth A fibrosarcoma implanted intradermally in mice. Growth of the tumor was inhibited when rTNF-alpha was given i.v. on day 7 or 11 after implantation, but the effect was countered when 5-FU was additionally given i.p. once a day on days 1-4 after implantation. Conversely, 5-FU given on days 5-8 after implantation augmented the antitumor effects of rTNF-alpha. Injection of carbon particles showed that fine capillaries did not develop in the tumors of mice treated with 5-FU on days 1-4 after implantation, but that a delicate network of capillaries developed in the tumors of both the mice treated with 5-FU on days 5-8 after implantation and the controls given saline. The results show that the timing of 5-FU treatment is important when attempting to enhance the antitumor effects of rTNF-alpha, and suggest that these effects are directly associated with newly formed fine capillaries in the tumor.

Enzyme activities of the nitric oxide-cGMP pathway in corpus cavernosum isolated from middle-aged rats

Cyclic guanosine-3',5'-monophosphate (cGMP)-mediated mechanisms play an important role in vasodilation and blood pressure regulation. We investigated basal activity of the nitric oxide (NO)-cGMP signal transduction pathway in corpus cavernosum from both middle-aged and young rats, and the electrical field stimulation-induced relaxation in the organ was also evaluated. In middle-aged rats, nitric oxide synthase (NOS) and cGMP-phosphodiesterase activities were significantly decreased; however, guanylate cyclase activity was similar. cGMP concentration, a secondary messenger of NO, remained almost the same level as compared with young rats. These results suggest that decrease in cGMP-phosphodiesterase activity is likely to account for the maintenance of cGMP concentration. In isolated corpus cavernosum from middle-aged rats, electrical field stimulation-induced relaxation was partially impaired. These results suggest that downregulation of the NOS and cGMP-phosphodiesterase activities are early events in the pathogenesis of erectile dysfunction.

The estrogenic and antiestrogenic activities of droloxifene in human breast cancers

The effects of a new antiestrogen, droloxifene (DROL, (E)-alpha-[p-[2-(dimethylamino)ethoxy]-phenyl]-alpha'-ethyl-3- stilbenol), on human breast cancer cells in vitro and in vivo were studied. Since phenol red has a binding affinity to the estrogen receptor (ER), we studied the activities of drugs in medium with or without this indicator. Estradiol-17 beta (E2) stimulated the growth of ER-positive breast cancer cells, MCF-7, ZR-75-1 and T-47D, in medium without phenol red, but not in medium containing this indicator. In medium without phenol red, DROL had no marked effects on the growth of MCF-7 and ZR-75-1, but slightly stimulated the growth of T-47D. Tamoxifen (TAM) stimulated the growth of these 3 cells. DROL dose-dependently inhibited the E2-induced stimulation of growth of these cells in medium without phenol red, but TAM inhibited the growth only at high concentrations. The growth of ER-negative breast cancer cells, MDA-MB-231, was not influenced by E2, DROL or TAM. DROL was more effective than TAM against ER-positive Br-10 breast carcinoma in nude mice, but neither drug had effects on ER-negative MX-1 breast carcinoma. These results suggest that DROL shows an antitumor effect on ER-positive breast cancers, being less estrogenic and more antiestrogenic than TAM.