INHIBITORY EFFECT OF DEMO ON THE GROWTH OF TRANSPLANTED HUMAN COLON CANCER IN NUDE MICE

A human colon cancer cell line Hce- 8693 was heterotransplanted in nude mice. Polyamine blosythesis Inhibitor a- dlfiuoromethylomithine (DFMO ) show a marked reproducible inhibition in this model. The size and weight of transplanted tumor In DFMO group were smaller than those of the control group and the average inhibition rate was 72.8% (P < 0.001) . DFMO showed higher tumor inhibitory rate than 5-Fu (35. 4%) (P<0. 001) . Furthermore. DFMO demonstrated less severe bone marrow inhibition in the nude mice than 5-Fu (20. 0% Vs 53. 2%. P<0. 001) .There was no synergistic action in these two drugs at the experimental dose. The concentration of putrescine and spermidine in the plasma and tumor tissue in the DFMO group were 70% lower than those of the control group (P<0. 001) . These results indicate that the anti-tumor effect of DFMO might be explained by the inhibition of polyamine biosynthesis and this study provides an experimental basis for future clinical application of DFMO.     

豆蔻提取物对人胃癌裸鼠移植瘤生长及血管生成的影响

[目的]观察豆蔻提取物对人胃癌细胞裸鼠移植瘤的生长和对肿瘤血管生成的影响。[方法]建立人胃癌SGC-7901细胞裸鼠皮下移植瘤模型（n=24）,随机分成4组（n=6）,对照组、豆蔻组、5-Fu组、联合组,各组按设计剂量给药。测定移植瘤体积、瘤重及抑瘤率;用免疫组化法检测各组移植瘤瘤体中血管内皮生长因子（VEGF）和微血管密度（MVD）的表达情况。[结果]豆蔻组、5-Fu组、联合组的瘤重和瘤体积明显低于对照组（P〈0.05）,3组抑瘤率分别为45.83%、66.96%和77.28%。联合组中VEGF表达率和MVD计数明显低于对照组（P〈0.05）。[结论]豆蔻提取物可抑制胃癌移植瘤的生长,与5-Fu联合应用具有协同作用,其作用机制可能与下调VEGF的表达、减少MVD有关。     

Effects of alpha-difluoromethylornithine on the growth of experimental Wilms' tumor and renal adenocarcinoma

Because polyamines are essential for cellular growth and differentiation, and because human renal carcinomas have spermidine levels that are higher than those in normal renal tissue, effects of 2-difluoromethylornithine (DFMO) on the growth of experimental renal tumors were investigated. DFMO is a specific enzyme-activated irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme controlling polyamine biosynthesis. DFMO (2%) in drinking water was administered to BALB/c mice with intrarenal transplants of a renal adenocarcinoma cell suspension and to Wistar/Furth rats with s.c. transplants of a Wilms' tumor. At 28 days, renal carcinomas in DFMO-fed mice weighed 72% less than those in control animals (p less than 0.001). Wilms' tumor weight was not affected by DFMO feeding. DFMO caused 72 to 75% inactivation of ornithine decarboxylase activity and reduced putrescine levels in renal carcinoma and Wilms' tumor, reduced spermidine levels in Wilms' tumor, and apparently raised spermine levels in the latter as a consequence. DNA content was not affected by DFMO feeding. The mean number of lung metastases in DFMO-fed, renal carcinoma-bearing mice was 0.1 and in controls was 1.4 (p less than 0.001). DFMO feeding increased survival of mice bearing renal carcinomas by 3.0 +/- 0.8 (S.E.) days (p less than 0.05), i.e., from 30.5 +/- 0.8 days to 33.5 +/- 1.2 days. DFMO did not affect the growth of Wilms' tumor; however, in renal adenocarcinoma, it reduced growth, prevented lung metastases, and increased survival.     

雷替曲塞对人胃癌裸鼠移植瘤生长的影响及其机制

  目的   初步探索雷替曲塞对人胃癌裸鼠皮下移植瘤生长的影响及其机制。   方法   1）建立人胃癌细胞MGC-803裸鼠皮下移植瘤模型；2）药物干预后观察荷瘤鼠一般情况、体重、瘤重并计算抑瘤率；3）流式细胞仪测定瘤细胞的周期分布和凋亡；4）采用RT-PCR、Western blot印迹法检测各组肿瘤p53 mRNA及p53蛋白的表达水平。   结果   经雷替曲塞及5-Fu作用后，与对照组相比，两组裸鼠的体重明显下降，瘤体积缩小，抑瘤率分别达到49.02%和45.75%。雷替曲塞组和5-Fu组瘤细胞的G₀/G₁期比例较对照组比例明显降低（P < 0.01），而S期比例较对照组明显升高（P < 0.01）。雷替曲塞组和5-Fu组裸鼠肿瘤p53 mRNA与蛋白表达水平均显著升高（P < 0.01），但雷替曲塞组和5-Fu组之间并无差异。   结论   1）雷替曲塞对人胃癌细胞MGC-803裸鼠移植瘤生长有抑制作用，且与5-Fu抑瘤效果相似；2）雷替曲塞可以诱导人胃癌细胞MGC-803裸鼠移植瘤细胞周期S期的阻滞，并诱导移植瘤细胞凋亡；3）雷替曲塞可通过上调p53 mRNA和蛋白的表达水平来发挥抑瘤作用。       

Successful treatment with DL-alpha-difluoromethylornithine in established human small cell variant lung carcinoma implants in athymic mice

We report that p.o. administration of DL-alpha-difluoromethylornithine (DFMO), a specific inhibitor of polyamine biosynthesis, markedly inhibits the growth of established implants of cultured human small cell lung carcinoma (SCC) in athymic (nude) mice. Human SCC tumor cells, from a cell line which exhibited cell death in culture in the presence of DFMO, were inoculated s.c. into athymic mice. The tumors were permitted to grow until they became palpable (0.05 cu cm, 3- to 5-mm-diameter nodules). The animals were then randomized into control, and early (low tumor burden) and late (high tumor burden) treatment groups which received 3% DFMO in the drinking water (5.0 g/kg/day). The tumors in the untreated control group grew to a size of 29 cu cm by 9 weeks, and these animals had a median survival of 9 weeks. The late treatment group began DFMO treatment 3 weeks after clinical tumor engraftment, when mean tumor size was 1.5 cu cm (1.2- to 1.5-cm-diameter nodules). Tumor growth was inhibited by 60% (11.4 cu cm) by Week 9 and survival was prolonged, with 83% survival at 10 weeks and a 56% increase in median survival to 14 weeks (p less than 0.05). The early treatment group received the same dose of DFMO beginning 1 week after tumor engraftment, when their mean tumor size was 0.1 cu cm (4- to 6-mm-diameter nodules). The early DFMO group had a 99% inhibition in tumor growth (0.3 cu cm) (p less than 0.05). Survival was also prolonged compared to the untreated controls, with 83% survival at 10 weeks and a median survival of 15 weeks (p less than 0.05). In both the early- and late-DFMO-treatment groups, no significant clinical toxicities were observed in the first 10 weeks, during which antitumor therapeutic effects were seen. DFMO may have a potential role in the treatment of sensitive human tumors such as SCC. The data suggest that DFMO may be most useful clinically in patients with SCC who have a low tumor burden. Thus, DFMO might be an important tool to produce long-term maintenance of initial clinical remissions induced by combination chemotherapy.     

膈下逐瘀汤逆转裸鼠移植瘤MDR-1表达的实验

目的 探讨膈下逐瘀汤对HCT-8/5-Fu裸鼠移植瘤多药耐药基因MDR-1表达的影响。方法 MTT法确认人结肠腺癌细胞HCT-8/5-Fu的耐药性及对其他化疗药VCR、VP-16、DDP的交叉耐药性后,将耐药细胞HCT-8/5-Fu接种于BABL/c无胸腺裸鼠右腋下,建立耐药性稳定的裸鼠移植瘤模型。移植瘤裸鼠模型随机分为四组：空白对照组(对照组)、5-Fu组、膈下逐瘀汤组(DSED组)、膈下逐瘀汤+5-Fu组(DSED+5-Fu组)。其中对照组予0.9%氯化钠溶液灌胃给药,其余组予腹腔注射5-Fu和(或)中药灌胃。连续给药14天后颈椎脱臼处死裸鼠。观察各组裸鼠移植瘤生长情况;RT-PCR法检测各瘤组织MDR-1 mRNA表达。结果 膈下逐瘀汤+5-Fu组、膈下逐瘀汤组、5-Fu组对裸鼠移植瘤的抑瘤率分别为54.9%、32.4%和7.0%（P<0.01）。RT-PCR结果显示膈下逐瘀汤+5-Fu组及膈下逐瘀汤组MDR-1 mRNA的表达量与对照组相比明显下降（P<0.01）,5-Fu组与对照组相比MDR-1 mRNA表达量略有升高,但差异无统计学意义。结论 膈下逐瘀汤对大肠癌多药耐药裸鼠移植瘤生长具有抑制作用,其机制可能与膈下逐瘀汤通过逆转耐药移植瘤多药耐药基因表达,增强肿瘤细胞对药物的敏感度。     

Antitumor efficacy of polyamine antimetabolites and mitomycin C under polyamine-free diet

Treatment of nude mice xenografted with human gastric cancer was carried out by polyamine antimetabolites combined with mitomycin C (MMC) and polyamine-free diet. Polyamine antimetabolites, alpha-difluoromethylornithine (DFMO) and ethylglyoxal-bis-guanylhydrazone (EGBG), were given ip in a daily dose of 1,000 mg/kg and 20 mg/kg, respectively, for 6 consecutive days. MMC 2.0 mg/kg was administered every other day. The polyamine-free diet was given from 4 days before start of the treatment through the end of the study. Although the tumor growth rate of the control group given polyamine-free diet was similar to that given normal diet, in the mice treated with EGBG, DFMO plus MMC, the antitumor effect in the polyamine-free diet group was superior to the normal diet group. In comparison with tumor growth suppression due to EGBG plus DFMO or MMC only, the polyamine-free diet group showed better result than the normal diet group to some extent. In mice treated with EGBG, DFMO plus MMC, tumor tissue spermine levels in the polyamine-free diet group were significantly depressed, compared to the normal diet group. Furthermore, marked suppression of DNA biosynthesis was observed in mice given EGBG, DFMO plus MMC together with the polyamine-free diet. These results suggest that combined treatments of polyamine antimetabolites and MMC revealed a marked enhancement of antitumor effects, under conditions of polyamine depletion, which may be responsible for the alteration in DNA structure.     

Chemoprevention of mouse colon tumors with difluoromethylornithine during and after carcinogen treatment

alpha-Difluoromethylornithine (DFMO) treatment has been shown to modify carcinogenesis in many experimental tumor models, including skin, breast, and colon. This study was designed to determine whether DFMO treatment can inhibit experimental mouse colon tumors after carcinogen treatment and whether an associated effect of DFMO on cell proliferation in colon mucosa occurs. Male CD1 mice (40 per group) received dimethylhydrazine (30 mg/kg/week x 6 weeks, s.c.) and various schedules of DFMO, 1% in drinking water: Group A, none; Group B, following dimethylhydrazine treatment; Group C, during dimethylhydrazine treatment; and Group D, continuously throughout the study. Measurements of RBC polyamine levels showed that DFMO treatment ablated putrescine levels and confirmed that a systemic biological effect was achieved. Analysis of tumor data showed a significant inhibitory effect of DFMO treatment on colon tumor (adenomas and adenocarcinomas) incidence in Groups B (24%) and D (20%) compared to control Group A (52%, P less than 0.05 A versus B, P less than 0.02 A versus D) and on squamous cell carcinomas of the anus in all groups (P less than 0.001 A versus B, P less than 0.05 A versus C, A versus D). No consistent effect of DFMO treatment on cell proliferation in colon mucosa was identified. This study supports the hypothesis that DFMO treatment alters events in the postinitiation phases of mouse colon tumorigenesis.     

Combined efficacy of polyamine antimetabolites and cis-diamminedichloroplatinum

The combined antitumor effects of the polyamine antimetabolites, alpha-difluoro methylornithine (DFMO) and methylglyoxal-bis-guanylhydrazone (MGBG), with CDDP were studied using human gastric cancer cells xenotransplanted into nude mice. DFMO (1000 mg/kg in two divided doses) and MGBG (50 mg/kg) were given IP for six consecutive days from the time when the xenotransplanted tumor weighted about 100 mg, and CDDP (3.0 mg/kg) was given IP every other day from the same time. Animals treated with DFMO plus MGBG with or without CDDP as well as with CDDP only displayed suppressed tumor growth, compared to untreated mice. In mice treated with these three drugs, however, tumor growth was rather rapid compared to those treated with CDDP only, although tumoral CDDP levels in animals given DFMO, MGBG and CDDP were higher than those given CDDP only. When DFMO, MGBG and CDDP or DFMO and MGBG were administered, tumoral spermidine and spermine levels decreased markedly. On the other hand, tumor DNA biosynthesis in the CDDP only group dropped markedly 24 hours after the termination of therapy. These results suggest that an alteration in the DNA structure caused by polyamine deficiency may prevent cross-link formation in DNA by CDDP.     

Effects of alpha-difluoromethylornithine and methylglyoxal bis(guanylhydrazone) on the growth of experimental renal adenocarcinoma in mice

alpha-Difluoromethylornithine (DFMO) and methylglyoxal bis-(guanylhydrazone) (MGBG) were tested against a murine renal adenocarcinoma, because polyamines are necessary for neoplastic cell growth and because human renal adenocarcinomas contain higher levels of spermidine than do normal renal cells; MGBG inhibits spermidine synthesis and has some activity against human renal tumors; DFMO irreversibly inhibits ornithine decarboxylase, the first rate-limiting enzyme controlling polyamine biosynthesis; and DFMO promotes intracellular accumulation of MGBG in experimental tumor models and human leukemia. DFMO (2%) in drinking water, MGBG (15 mg/kg i.p.), or a combination of DFMO and MGBG was administered daily to BALB/c mice (n = 80) with intrarenal transplants of renal adenocarcinoma cells. At 28 days, renal carcinomas weighed 64 and 73% less, respectively, in DFMO- and DFMO-MGBG-treated mice than in control animals (p less than 0.01). MGBG alone had no antigrowth effect. DFMO-MGBG reduced the total metastatic index (total number of metastases/total number of animals) to 1.2 versus 3.6 in control animals (p less than 0.01) and increased survival by 12.3 +/- 1.5 (S.E.) days, from 30.8 to 42.5 days (p less than 0.05). Compared with control, DFMO-, or MGBG-treated animals, DFMO-MGBG exposure reduced tumor growth and the number of metastases, prevented metastases in some animals (47%), and increased survival of mice bearing renal adenocarcinomas. DFMO also appeared to selectively increase the uptake of [14C]MGBG by tumor tissue, which may help to explain the enhanced synergistic antigrowth effect of DFMO and MGBG against this murine renal adenocarcinoma.