A methylester of the glucuronide prodrug DOX-GA3 for improvement of tumor-selective chemotherapy

The glucuronide prodrug of doxorubicin, DOX-GA3, can be selectively activated in tumors by extracellular human beta-glucuronidase, resulting in a better therapeutic index than doxorubicin. DOX-GA3, however, is rapidly excreted by the kidney. We hypothesized that slow release of DOX-GA3 from its methylester, DOX-mGA3, by esterase activity in blood would result in improved circulation half-life (t(1/2)) of DOX-GA3. DOX-mGA3 was synthesized more efficiently with an overall yield of 60% as compared to 37% in the case of DOX-GA3. We showed that DOX-mGA3 was enzymatically converted to DOX-GA3 with a t(1/2) of approximately 0.5 min in mouse plasma to 2.5 h in human plasma, which was in agreement with differences in esterase activity between species. DOX-mGA3, similar to DOX-GA3, was at least 37-fold less potent than the parent drug doxorubicin in growth inhibition of four different human malignant cell lines in vitro. Incubation of OVCAR-3 cells with DOX-mGA3 in combination with an excess of human beta-glucuronidase (0.05 U mL(-1)) resulted in a similar growth inhibition to that of doxorubicin. Intravenous administration of DOX-mGA3 in FMa-bearing mice resulted in an area under the concentration versus time curve (AUC) of DOX-GA3 in tumor and most normal tissues that was 2.5- to 3-fold higher than after the same dose of DOX-GA3 itself. In tumor tissue, this was accompanied by a 2.7-fold increase in the AUC of doxorubicin from DOX-mGA3 than from DOX-GA3. In conclusion, an advantage of DOX-mGA3 over DOX-GA3 is that this prodrug can be produced with a higher yield. Another important advantage is the improved pharmacokinetics of the lipophilic DOX-mGA3 as compared to that of the hydrophilic DOX-GA3. This effect may even be more pronounced in man, because of the lower plasma esterase activity than measured in mice.     

Antitumor activity and biodistribution of cisplatin nanocapsules in nude mice bearing human ovarian carcinoma xenografts

Cisplatin nanocapsules represent a novel lipid formulation of the anticancer drug cis-diamminedichloridoplatinum(II) (cisplatin), characterized by an unprecedented cisplatin-to-lipid molar ratio, and exhibiting strongly increased in-vitro cytotoxicity compared with the free drug. In this study, antitumor efficacy and biodistribution of PEGylated cisplatin nanocapsules were compared with those of the free drug in a mouse tumor model. Nude mice bearing human ovarian carcinoma OVCAR-3 xenografts were treated twice with a 1-week interval by intravenous administration of cisplatin nanocapsules or cisplatin in solution, and the growth inhibitory effects were determined by measurement of tumor volumes. At a dose of 3 mg cisplatin/kg, corresponding to the maximum tolerated dose of cisplatin nanocapsules, cisplatin nanocapsules and cisplatin in solution exhibited similar therapeutic effectiveness, reducing tumor growth by 90% at day 20 after first injection. The platinum biodistribution was assayed by analyzing plasma and tissues for total platinum content by nonflame atomic absorption spectroscopy. Plasma and tumor concentrations of platinum were similar for both formulations. During the first hour after injection of cisplatin nanocapsules, the platinum content of the kidney was 40% less than that after administering the free drug. Platinum from nanocapsules showed rapid and 4.5-fold higher accumulation in the liver compared with free cisplatin, and, at a slower rate, accumulation to a high concentration in the spleen. We conclude that the formulation of cisplatin nanocapsules inhibits the growth of OVCAR-3 xenografts in nude mice, albeit to a similar extent as free cisplatin. The results suggest that the antitumor efficacy of the nanocapsules could be improved by preventing rapid clearance from circulation.     

Response of human tumor xenografts in athymic nude mice to docetaxel (RP 56976, Taxotere®)

Summary Docetaxel (Taxotere^?, RP 56976, NSC 628503), a new taxoid, was evaluated for preclinical evidence of anticancer activity in athymic nude (NCr-nu) mice bearing established, subcutaneously (s.c.) implanted human tumor xenografts CX-1 or KM20L2 (colon carcinomas), LX-1 (lung carcinoma), MX-1 (mammary carcinoma), and SK-MEL-2 (melanoma). Other evaluations used OVCAR-3 (ovarian carcinoma) xenografts implanted intraperitoneally (i.p.). Docetaxel was administered intravenously (i.v.) every 4 days for 3 injections (q4d×3) except for one OVCAR-3 experiment in which the drug was given i.p. every 7 days for 3 injections. Tumor measurements, animal body weights, and mortality were determined. The highest dosage used (50 mg/kg/dose) was toxic in all experiments in which the 4-day treatment interval was used. The maximally tolerated dosage (MTD) ranged from 15 to 33 mg/kg/dose. Therapeutic responses among these xenografts ranged from clinically important long-term tumor-free survivors (MX-1, SK-MEL-2, and OVCAR-3) to tumor growth delays of various durations (CX-1, LX-1, and KM20L2). The response of SKMEL-2, a xenograft highly refractory to available drugs, was particularly noteworthy. These results are indicative of a broad spectrum of antitumor activity for docetaxel.     

Benzyl ether-linked glucuronide derivative of 10-hydroxycamptothecin designed for selective camptothecin-based anticancer therapy

A beta-glucuronidase-activated prodrug approach was applied to 10-hydroxycamptothecin, a Camptotheca alkaloid with promising antitumor activity but poor water solubility. We synthesized a glucuronide prodrug of 10-hydroxycamptothecin ( 7) in which glucuronic acid is connected via a self-immolative 3-nitrobenzyl ether linker to the 10-OH group of 10-hydroxycamptothecin. Compound 7 was 80 times more soluble than 10-hydroxycamptothecin in aqueous solution at pH 4.0 and was stable in human plasma. Prodrug 7 was 10- to 15-fold less toxic than the parent drug to four human tumor cell lines. In the presence of beta-glucuronidase, prodrug 7 could be activated to elicit similar cytotoxicity to the parent drug in tumor cells. Enzyme kinetic studies showed that Escherichia coli beta-glucuronidase had a quite low K m of 0.18 microM for compound 7 and exhibited 520 times higher catalytic efficiency for 7 than for 6 (a glucuronide prodrug of 9-aminocamptothecin). Molecular modeling studies predicted that compound 7 would have a higher binding affinity to human beta-glucuronidase than compound 6. Prodrug 7 may be useful for selective cancer chemotherapy by a prodrug monotherapy (PMT) or antibody-directed enzyme prodrug therapy (ADEPT) strategy.     

The activity profile of the hexacyclic camptothecin derivative DX-8951f in experimental human colon cancer and ovarian cancer

DX-8951f or exatecan mesylate ((1S,9S)-1-amino-9-ethyl-5-fluoro-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3',4':6,7]indolizino[1,2-b]quinoline-10-13(9H,15H)-dione methanesulfonate dihydrate), is a new water-soluble derivative of camptothecin. We determined the activity of DX-8951f in experimental human colon cancer and ovarian cancer, being tumor types sensitive to camptothecins. With the use of the MTT assay, DX-8951f was more potent than SN-38 in four out of five human colon cancer cell lines and three out of four human ovarian cancer cell lines (P<0.05). DX-8951f was considerably more potent than topotecan in all cell lines tested (P<0.05). Prolonged exposure to DX-8951f resulted in a greater increase in inhibition of cell proliferation as compared to that obtained with SN-38 or topotecan (P<0.05). Overexpression of Pgp, MRP1, and LRP did not affect the in vitro activity of DX-8951f. DX-8951f administered daily x 5 or weekly x 2 resulted in growth inhibition <50% in two human colon cancer xenografts grown s.c. in nude mice. In three human ovarian cancer xenografts, however, >50% growth inhibition was observed at both schedules. In the OVCAR-3 human ovarian cancer model, DX-8951f showed considerably greater activity than topotecan (P<0.01). DX-8951f combined with cisplatin or paclitaxel did not indicate the presence of a pharmacological interaction. In OVCAR-3 xenografts the combination was clearly more effective than DX-8951f alone, as the number of complete remissions increased substantially. In conclusion, this study shows that DX-8951f is highly potent in vitro and highly effective in experimental human ovarian cancer in vivo. Prolonged exposure to DX-8951f in vitro greatly increased the antiproliferative effects, which may be a rationale for testing a continuous infusion schedule in the clinic. Addition of cisplatin or paclitaxel improved the in vivo antitumor effects of DX-8951f.     

Design and synthesis of water-soluble glucuronide derivatives of camptothecin for cancer prodrug monotherapy and antibody-directed enzyme prodrug therapy (ADEPT).

Glucuronide prodrugs of 9-aminocamptothecin were synthesized. Prodrug 4, in which 9-aminocamptothecin was connected to glucuronic acid by an aromatic spacer via a carbamate linkage, was stable in both aqueous solution and human plasma. Prodrug 4 and its potassium salt 12 were 20-80-fold less toxic than 9-aminocamptothecin to human tumor cell lines. The simultaneous addition of beta-glucuronidase and 4 or 12 to tumor cells resulted in a cytotoxic effect equal to that of 9-aminocamptothecin alone. Prodrugs 4 and 12 were over 80 and 4000 times more soluble than 9-aminocamptothecin in aqueous solutions at pH 4.0, respectively. Compounds 4 and 12 may be useful for prodrug monotherapy of tumors that accumulate extracellular lysosomal beta-glucuronidase as well as for antibody-directed enzyme prodrug therapy (ADEPT) of cancer.     

Expression and function of β-glucuronidase in pancreatic cancer: potential role in drug targeting

Improvement of non-surgical strategies is a pivotal task in the treatment of pancreatic cancer. Response to treatment with most anticancer agents has been very poor, probably due to insufficient drug concentration in tumor tissue. Increased response rates during chemotherapy might be achieved by dose escalation; however, this approach is often hampered by severe side effects. One strategy to overcome these adverse effects is application of nontoxic glucuronide prodrugs from which the active moiety is released by beta-glucuronidase within or near the tumor. The use of glucuronide prodrugs in pancreatic cancer requires increased expression of the enzyme in the diseased tissue, a problem that has not been addressed so far. We therefore investigated function and expression of beta-glucuronidase in tissue samples from human healthy pancreas (n=7) and pancreatic adenocarcinoma (n=8), respectively. Comparing the ability of tissue homogenates to cleave the standard substrate 4-methylumbelliferyl-beta-D-glucuronide, we found a significantly increased specific beta-glucuronidase activity (P<0.05) in pancreatic cancer (median: 133; 75% percentile: 286; 25% percentile: 111 nmol/mg per h) as compared to healthy pancreas (median: 74; 75% percentile: 113; 25% percentile: 71 nmol/mg per h). Enzyme kinetic experiments with the model prodrug N-[4-beta-glucuronyl-3-nitrobenzyloxycarbonyl] doxorubicin (HMR 1826) demonstrated bioactivation of HMR 1826 by pancreatic beta-glucuronidase. Enzymatic activity was found to be closely related to enzyme contents (r=0.87) as assessed by Western blot analysis. Our data indicate that increased beta-glucuronidase activity in pancreatic cancer seems to be due to an elevated steady-state level of the protein. This may be the basis for new therapeutic strategies in treatment of pancreatic carcinoma by using glucuronide prodrugs of anticancer agents.     

Cytosolic beta-glycosidases for activation of glycoside prodrugs of daunorubicin

Human cytosolic beta-glycosidase is a small monomeric enzyme that is active under physiological conditions, which might be ideal for enzyme-prodrug therapy. We have previously reported the synthesis of a galactoside (DNR-GlA3) and a glucoside (DNR-GsA3) prodrug of daunorubicin. In the present study, we established that cellular uptake of DNR-GlA3 and DNR-GsA3 was low in contrast to that of daunorubicin. Recombinant human beta-glycosidase converted both prodrugs to daunorubicin as shown by liquid chromatography. The kinetics of the conversion of DNR-GlA3 and DNR-GsA3 by human beta-glycosidase, however, was unfavorable as the K(m) values were, respectively, 3- and 6-fold higher than those of another mammalian beta-glycosidase of bovine origin. The V(max) values were, respectively, 3.3 and 8.5nmol/hr/mg as compared to 158.3 and 147.8nmol/hr/mg of the bovine enzyme. Treatment of OVCAR-3 cells with human beta-glycosidase (0.5U/mL) and 0.5 microM DNR-GlA3 or DNR-GsA3 resulted in, respectively, 86 and 81% cell growth inhibition, while the prodrugs alone inhibited growth to only 19 and 1%. Treatment of cells with the bovine enzyme and the prodrugs inhibited cell growth more efficiently. We conclude that the endogenous intracellular beta-glycosidase is not available for extracellular prodrug activation. Thus, the incorporation of the enzyme in enzyme-prodrug therapy might be an elegant approach to achieve tumor-specific prodrug conversion. The efficiency of glycoside prodrug conversion might be improved by design of a prodrug that is more readily activated by human beta-glycosidase or by evolution of the enzyme into a mutant form that displays high activity towards these prodrugs.     

反应停对人癌裸鼠肿瘤及新血管形成的影响

目的:观察反应停对人卵巢癌细胞(OVCAR-3)及人结肠癌细胞(HCT-8)生长及肿瘤组织内新血管形成的影响。方法:建立人癌裸鼠异种移植的模型,将接种肿瘤后的裸鼠分别灌胃给予不同剂量的反应停,并与正常对照组进行比较,观察肿瘤生长的情况;采用免疫组化检验方法检测肿瘤组织中微血管密度(MVD)。结果:对人癌裸鼠OVCAR-3肿瘤,反应停中、高剂量组均可显著抑制肿瘤生长(P<0.05、P<0.01),对HCT-8的生长却无明显影响,但反应停均呈剂量依赖性降低上述肿瘤组织MVD。结论:反应停的抗肿瘤作用可能与抗新血管形成作用无关。     

Improved brain delivery of AZT using a glycosyl phosphotriester prodrug.

The concentration of AZT in mice plasma and brain was measured using HPLC after an ingestion of 20 mg/kg of AZT or the molar equivalent of hexadecyl 2-(alpha-D-mannopyranosidyl)ethyl 3'-azido-3'-deoxy-5'-thymidinyl phosphate 3. The results demonstrated the promising qualities of the prodrug 3 which gave AZT-5'-phosphate as the main metabolite: the total concentration of AZT derivatives detected in brain presented a peak of 156 nmol/g (5 nmol/g for AZT) at 1 h; the half-life was about 24 h (1 h for AZT) with an AUC of 4366 nmol h/g as compared to 4 nmol h/g for AZT. The lipophilic properties of 3 were confirmed by its in vitro transport of inside synaptosomes. The derivative 2-(alpha-D-mannopyranosidyl)ethyl 3'-azido-3'-deoxy-5'-thymidinyl phosphate (2) provided also a good delivery of AZT to the central nervous system, with values intermediate between those of AZT and 3.     

Synthesis, cleavage profile, and antitumor efficacy of an albumin-binding prodrug of methotrexate that is cleaved by plasmin and cathepsin B

Cathepsin B and plasmin are intra- or extracellular proteases that are overexpressed by several solid tumors. In order to exploit both proteases as molecular targets for tumor-specific cleavage of prodrugs, an albumin-binding formulation of methotrexate was developed that incorporated the peptide sequence D-Ala-Phe-Lys as the protease substrate. Albumin is a suitable carrier for cytostatic agents due to passive accumulation in solid tumors. Synthesis was performed by coupling the peptide linker EMC-D-Ala-Phe-Lys(Boc)-Lys-OH (EMC = epsilon-maleimidocaproic acid) to the gamma-COOH group of alpha-tert-butyl protected methotrexate. After cleavage of the protective groups and purification on reverse phase HPLC, a highly water-soluble methotrexate-peptide derivative was obtained that binds rapidly and selectively to human serum albumin. The albumin-bound form of the prodrug was shown to be efficiently cleaved by cathepsin B and plasmin as well as in an ovarian carcinoma homogenate (OVCAR-3) liberating a methotrexate-lysine derivative. In an OVCAR-3 xenograft model, the prodrug at a dose of 4x15 mg/kg methotrexate equivalents demonstrated distinctly superior antitumor efficacy compared to free methotrexate at a dose of 4x100 mg/kg [T/C(%) for MTX = 69; T/C(%) for MTX prodrug = 29]. The data provide a further proof of concept for the development of albumin-binding, enzymatically cleavable prodrugs of anticancer drugs.     

Efficacy of increasing the therapeutic index of irinotecan, plasma and tissue selenium concentrations is methylselenocysteine dose dependent

This study was designed to understand the basis for the efficacy of methylselenocysteine (MSC) in increasing the therapeutic index of irinotecan against human tumor xenografts. Nude mice bearing human head and neck squamous cells carcinoma xenografts (FaDu and A253) were treated orally with different doses of MSC and irinotecan. Plasma, tumor and normal tissue samples were collected at different times after MSC treatments and were analyzed for selenium (Se) concentration using electrothermal atomic absorption spectrophotometry. MSC is highly effective in modulating the therapeutic index of irinotecan. Enhanced irinotecan efficacy was greater in FaDu tumors (100% CR) than in A253 tumors (60% CR), and depended on MSC dose with a minimum effective dose of 0.01 mg/dx28. The highest plasma Se concentration was achieved 1h after a single dose and 28 d after daily treatments of MSC. The ability of FaDu tumors to retain Se was significantly better than A253 tumors, and the highest Se concentration in normal tissue was achieved in the liver. Peak plasma and tissue Se concentrations were functions of the dose and duration of MSC treatment. The MSC-dependent increase in Se level in normal tissues may contribute to the protective effect against irinotecan toxicity observed in those tissues. Intratumoral total Se concentration was not found to be predictive of the combination therapy response rates. There is a critical need to develop a method to measure the active metabolite of MSC, rather than total Se.     

Pharmacokinetics and Tissue Distribution of (±)-3′-Azido-2′,3′-dideoxy-5′-O-(2-bromomyristoyl)thymidine,a Prodrug of 3′-Azido-2′,3′-dideoxythymidine (AZT) in Mice

The in-vivo biodistribution and pharmacokinetics in mice of 3′-azido-2′,3′-dideoxythymidine ( 1 , AZT), 2-bromomyristic acid ( 2 ) and their common prodrug, (±)-3′-azido-2′,3′-dideoxy-5′-O-(2-bromomyristoyl)thymidine ( 3 ) are reported. The objectives of the work were to enhance the anti-human immunodeficiency virus and anti-fungal effects of 1 and 2 by improving their delivery to the brain and liver. The pharmacokinetics of AZT (βt1/2 (elimination, or beta-phase, half-life) = 112.5 min; AUC (area under the plot of concentration against time) = 29.1 ± 2.9 μmol g^?1 min; CL (blood clearance) = 10.5 ± 1.1 mL min^?1 kg^?1) and its ester prodrug ( 3 , βt1/2 = 428.5 min; AUC = 17.3 ± 4.7 μmol g^?1 min; CL = 17.6 ± 4.8 mL min^?1 kg^?1) were compared after intravenous injection of equimolar doses (0.3 mmol kg^?1) via the tail vein of Balb/c mice (25.30 g). The prodrug was rapidly converted to AZT in-vivo, but plasma levels of AZT (peak concentration 0.17 μmol g^?1) and AUC (12.3 μmol min g^?1) were lower than observed after AZT administration (peak concentration 0.36 μmol g^?1; AUC 29.1 μmol min g^?1). The prodrug also accumulated rapidly in the liver immediately after injection, resulting in higher concentrations of AZT than observed after administration of AZT itself (respective peak concentrations 1.11 and 0.81 μmol g^?1; respective AUCs 42.5 and 12.7 μmol min g^?1). Compared with doses of AZT itself, 3 also led to significantly higher brain concentration of AZT (25.7 compared with 9.8 nmol g^?1) and AUCs (2.8 compared with 1.4 μmol min g^?1). At the doses used in this study the antifungal agent 2-bromomyristic acid was measurable in plasma and brain within only 2 min of injection. Hepatic concentrations of 2-bromomyristic acid were higher for at least 2 h after dosing with 3 than after dosing with the acid itself. In summary, comparative biodistribution studies of AZT and its prodrug showed that the prodrug led to higher concentrations of AZT in the brain and liver. Although the prodrug did not result in measurably different concentrations of 2-bromomyristic acid in the blood and brain, it did lead to levels in the liver which were higher than those achieved by dosing with the acid itself.     

Pharmacokinetics and pharmacodynamics of sibrafiban, an orally administered IIb/IIIa antagonist, in patients with acute coronary syndrome.

Sibrafiban is a double prodrug that is converted to the inactive single prodrug and to the active IIb/IIIa antagonist following oral administration. Pharmacokinetics (PK) and pharmacodynamics (PD) of oral sibrafiban and its metabolites were evaluated in patients postacute coronary syndrome receiving once- or twice-daily sibrafiban for up to 28 days at several dose levels. Mean peak concentrations of sibrafiban were < 5 ng/mL. Peak single prodrug concentrations occurred 1.7 +/- 1.0 (mean +/- SD) hours after sibrafiban dosing. Total apparent plasma clearance of the single prodrug was 40 +/- 15 L/h, and the elimination half-life was 2.3 +/- 0.8 hours. Mean values of the steady-state pharmacokinetics for total concentrations of the active drug over all doses were: time to peak plasma concentration, 5.0 +/- 1.7 hours; apparent clearance, 13.9 +/- 3.9 L/h; and half-life, 11.0 +/- 2.8 hours. Once-daily dosing resulted in high peak-trough excursions in active drug concentrations: trough concentrations were 21% +/- 6% of peak. Twice-daily dosing resulted in an AUC for the active drug on Day 28 that was 168% +/- 36% of that on Day 1, and steady-state trough concentrations were 54% +/- 10% of peak with sustained inhibition of platelet aggregation. Dose-adjusted steady-state active drug concentrations increased with increasing age and with decreasing renal function and body weight.     

Modulation of 5-fluorouracil host toxicity by 5-(benzyloxybenzyl)barbituric acid acyclonucleoside, a uridine phosphorylase inhibitor, and 2',3',5'-tri-O-acetyluridine, a prodrug of uridine

Administration of 200 mg/kg of 5-fluorouracil (FUra) to mice bearing human colon carcinoma DLD-1 xenografts resulted in 100% mortality. Oral administration of 2000 mg/kg of 2',3',5'-tri-O-acetyluridine (TAU), a prodrug of uridine, in combination with 120 mg/kg of 5-(benzyloxybenzyl)barbituric acid acyclonucleoside (BBBA), the most potent known inhibitor of uridine phosphorylase (UrdPase, EC 2.4.2. 3), 2 hr after the administration of the same dose of FUra completely protected the mice (100% survival) from the toxicity of FUra. This combination also reduced tumor weight by 67% compared with 46% achieved by the maximum tolerated dose (50 mg/kg) of FUra alone. Similarly, administration of BBBA plus TAU 1 hr before or 4 hr after the administration of FUra reduced the tumor weight by 53 and 37%, respectively. However, these schedules were less effective in protecting the host from the toxicity of FUra than when the treatment was carried out at 2 hr after FUra administration. TAU alone did not protect from FUra host toxicity. The efficiency of the BBBA plus TAU combination in rescuing from FUra host toxicities is attributed to the exceptional effectiveness of this combination in raising and maintaining higher plasma uridine concentrations than those achieved by TAU alone or by equimolar doses of uridine (Ashour et al., Biochem Pharmacol 51: 1601-1612, 1996). The present results suggest that the BBBA plus TAU combination can provide a better substitute for the massive doses of uridine required to achieve the high levels of uridine necessary to rescue or protect from FUra host toxicities without the toxic side-effects associated with such doses of uridine. The combination of TAU plus BBBA may also allow the escalation of FUra doses for better chemotherapeutic efficacy. Alternatively, the combination may be used as a rescue regimen in the occasional cases where cancer patients receive a lethal overdose of FUra.     

Menadione induces the formation of reactive oxygen species and depletion of GSH-mediated apoptosis and inhibits the FAK-mediated cell invasion

Menadione induces apoptosis in tumor cells. However, the mechanism of apoptosis in ovarian cancer cells exposed to menadione is not clear. In addition, it is unclear whether menadione-induced apoptosis is mediated by the depletion of glutathione (GSH) contents that is associated with the formation of reactive oxygen species. Furthermore, the effect of menadione on the invasion and migration of human epithelial ovarian cancer cells has not been studied. Therefore, we investigated the effects of menadione exposure on apoptosis, cell adhesion, and cell migration using the human epithelial ovarian carcinoma cell lines OVCAR-3 and SK-OV-3. The results suggest that menadione may induce apoptotic cell death in ovarian carcinoma cell lines by activating the mitochondrial pathway and the caspase-8- and Bid-dependent pathways. The apoptotic effect of menadione appears to be mediated by the formation of reactive oxygen species and the depletion of GSH. Menadione inhibited fetal-bovine-serum-induced cell adhesion and migration of OVCAR-3 cells, possibly through the suppression the focal adhesion kinase (FAK)-dependent activation of cytoskeletal-associated components. Therefore, menadione might be beneficial in the treatment of epithelial ovarian adenocarcinoma and combination therapy.     

顺铂联合8-硝基白杨素对人卵巢癌细胞裸鼠移植瘤生长的影响

目的 研究顺铂联合8-硝基白杨素对人卵巢癌COC1细胞裸鼠移植瘤生长的影响。方法 建立人卵巢癌COC1细胞裸鼠皮下移植瘤模型,随机分成4组,每组5只：生理盐水组、8-硝基白杨素组、顺铂组、8-硝基白杨素+顺铂组。观察各组裸鼠移植瘤体积、重量及裸鼠体质量的变化;裸鼠血清乳酸脱氢酶、谷丙转氨酶、肌酐值和外周血白细胞计数的变化;FCM测定瘤组织细胞凋亡率;Western blot分析瘤组织细胞凋亡的可能分子生物学机制。结果 与顺铂组和8-硝基白杨素组相比,顺铂联合8-硝基白杨素联合作用COC1细胞裸鼠移植瘤后,移植瘤的体积、移植瘤的重量均明显降低(P<0.05);与顺铂组相比,顺铂联合8-硝基白杨素联合组裸鼠体质量无明显差异(P>0.05),裸鼠血清乳酸脱氢酶、谷丙转氨酶、肌酐值和外周血白细胞计数无明显差异(P>0.05);顺铂和8-硝基白杨素联合作用COC1细胞16 d后,COC1细胞发生凋亡,同时bcl-2蛋白表达降低,caspase-3蛋白表达增高。结论 顺铂联合8-硝基白杨素通过降低bcl-2蛋白表达,活化caspase-3蛋白表达来抑制人卵巢癌COC1细胞裸鼠移植瘤生长。     

Preclinical efficacy of Virulizin in human breast,ovarian and prostate tumor models

Virulizin is a novel biological response modifier (BRM) approved for the treatment of melanoma and is currently in a phase III clinical trial against advanced pancreatic cancer. The purpose of this study was to define the anti-cancer activity of Virulizin against a number of solid human tumors. The therapeutic effect of Virulizin was evaluated in mouse xenograft models, and the results demonstrate that Virulizin has high efficacy against breast, ovarian and prostate tumor xenografts. Seventy-seven percent inhibition, with an optimal T/C value of 24.8%, was observed in human beast MDA-MB-231 xenografts treated with Virulizin as compared to saline-treated controls (p=0.0004). In human ovarian SK-OV-3 tumor xenografts, administration of Virulizin inhibited tumor growth by 77.6% compared to saline controls (p=0.0439). Furthermore, high anti-tumor activity was also demonstrated in DU145 and PC-3 prostate tumor xenografts, as indicated by 72.6 and 49.1% suppression of tumor growth (versus saline controls, p=0.0007 or p=0.0049), respectively. Direct comparisons with the anti-tumor activities of conventional drugs demonstrated that Virulizin has higher or equal efficacy against all four tumors tested. Finally, addition of Virulizin into co-cultures of tumor cells and macrophages stimulated the cytolytic activity of the macrophages against the tumor cells in a dose-dependent manner. This result suggests that stimulation of immune cells is at least part of the anti-tumor mechanism of action of Virulizin. These results clearly demonstrate that Virulizin inhibits the growth of human breast, ovarian and prostate tumors, indicating great potential for expansion of the clinical indications for this novel BRM.     

Effects of chemotherapy and/or radiotherapy on survivin expression in ovarian cancer

Survivin, a member of apoptosis protein inhibitor family, is upregulated in various malignancies, especially in chemotherapy- and/or radiation-resistant cell lines. In this study, the correlation between the level of survivin expression and degree of apoptosis was investigated in three ovarian cancer lines (two chemoresistant cell lines SKOV-3 and OVCAR-3, as well as one chemosensitive cell line OV2008) treated with 5 microg/ml of cisdiamminedichloroplatinum (cisplatin, CDDP) for 24 h, 2 Gy of (60)Co irradiation, or 5 microg/ml CDDP for 3 h plus 2 Gy of (60)Co, respectively. We also evaluated the survivin mRNA abundance in patients with advanced ovarian cancers during CDDP treatment. In the ovarian cancer cell lines, survivin mRNA abundance and protein contents were significantly increased after the treatments while the apoptotic rates did not change in SKOV-3 and OVCAR-3. Moreover, in OVA2008 cells the expression of survivin decreased and the apoptotic rate significantly increased after CDDP and combined treatments. Survivin mRNA was not detectable in normal ovarian tissues and benign ovarian tumors. However, it was observed in the resected tumor specimens from 20 patients with advanced ovarian cancer. These results suggested that survivin may play an important role in the resistance to chemotherapy and radiotherapy in ovarian cancer cell lines and in the progression of ovarian tumors. Survivin may also provide a pivotal prognostic implication for epithelial ovarian carcinomas.