Modulatory influence of oral contraceptive pills Ovral and Noracycline on 3-methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse.

The present study reports the modulatory influences of combined oral contraceptive formulations, Ovral (0.05 mg ethinylestradiol plus 0.5 mg norgestrel per pill) and Noracycline (0.05 mg ethinylestradiol plus 0.1 mg lynestrenol per pill), on methylcholanthrene (MCA)-induced carcinogenesis in the uterine cervix of Swiss albino mouse. Placement of cotton thread impregnated with beeswax containing approximately 300 micrograms of MCA yielded cervical tumors in 0.0%, 8.6% and 26% animals, respectively, in 30, 60 and 90 days. Concomitant treatments with doses D1 (1/2000th of a pill), D2 (1/200th of a pill) and D3 (1/20th of a pill) of Ovral yielded cervical tumors in 0.0%, 0.0% and 4.5% mice at 30 days, 0.0%, 6.2% and 10% mice at 60 days and in 3.3% (P less than 0.05), 3.4% (P less than 0.05) and 47% mice at 90 days, respectively. Likewise, concomitant treatments with doses D1 (1/2000th of a pill), D2 (1/200th of a pill) and D3 (1/20th of a pill) of Noracycline yielded cervical tumors in 0.0%, 0.0%, 16.6% mice at 30 days, 4%, 3.7% and 54% (P less than 0.05) mice at 60 days and 3.2% (P less than 0.05), 20% and 63% (P less than 0.05) of mice at 90 days, respectively. Both Ovral and Noracycline displayed biphasic action on MCA-induced cervical carcinogenesis in mice. At lower dose levels (D1 and D2), they were inhibitory while at the higher dose level (D3) they were augmentatory in their actions. Both pills also significantly enhanced the incidence of cervical hyperplasia.     

Modulatory Influence of Oral Contraceptive Pills Ovral and Noracycline on 3-Methylcholanthrene-induced Carcinogenesis in the Uterine Cervix of Mouse

The present study reports the modulatory influences of combined oral contraceptive formulations, Ovral (0.05 mg ethinylestradiol plus 0.5 mg norgestrel per pill) and Noracycline (0.05 mg ethinylestradiol plus 0.1 mg lynestrenol per pill), on methylcholanthrene (MCA)-induced carcinogenesis in the uterine cervix of Swiss albino mouse. Placement of cotton thread impregnated with beeswax containing ∼ 300 μg of MCA yielded cervical tumors in 0.0%, 8.6% and 26% animals, respectively, in 30, 60 and 90 days. Concomitant treatments with doses D₁ (1/2000th of a pill), D₂ (1/ 200th of a pill) and D₃ (1/20th of a pill) of Ovral yielded cervical tumors in 0.0%, 0.0% and 4.5% mice at 30 days, 0.0%, 6.2% and 10% mice at 60 days and in 3.3% (P<0.05), 3.4% (P<0.05) and 47% mice at 90 days, respectively. Likewise, concomitant treatments with doses D₁ (1/2000th of a pill), D₂ (1/200th of a pill) and D₃ (1/20th of a pill) of Noracycline yielded cervical tumors in 0.0%, 0.0%, 16.6% mice at 30 days, 4%, 3.7% and 54% (P<0.05) mice at 60 days and 3.2% (P<0.05), 20% and 63% (P<0.05) of mice at 90 days, respectively. Both Ovral and Noracycline displayed biphasic action on MCA-induced cervical carcinogenesis in mice. At lower dose levels (D₁ and D₂), they were inhibitory while at the higher dose level (D₃) they were augmentatory in their actions. Both pills also significantly enhanced the incidence of cervical hyperplasia.     

Inhibitory action of dehydroepiandrosterone on methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse

The present paper reports the chemopreventive action of Dehydroepiandrosterone (DHEA) on Methylcholanthrene- (MCA) induced carcinogenesis in the uterine cervices of adult virgin Swiss albino mice. Placement of sterile double cotton thread impregnated with beeswax containing 600 micrograms of MCA in the cervical canal produced tumors in 85.7% of mice in 16 weeks. When such carcinogen-containing threads were inserted into the uterine cervices of mice that were being fed on diets of 0.025%, 0.05% and 0.1% DHEA for a period of two preinsertion and sixteen postinsertion weeks, the cervical tumor incidences were reduced to 59.0%, 34.7% (P less than 0.01) and 14.2% (P less than 0.01), respectively. It is inferred that DHEA inhibits MCA-induced cervical carcinogenesis and the inhibitory action is dependent upon the dose of the drug.     

Studies of effects of recombinant human tumor necrosis factor on autochthonous tumor and transplanted normal tissue in mice

The acute hemorrhagic necrosis of tumor nodules caused by the systemic administration of recombinant human tumor necrosis factor alpha (rhTNF-alpha) has been partially attributed to changes in tumor neovascularity. In this study, the effects of rhTNF-alpha were tested on primary autochthonous sarcomas induced in C57BL/6 mice by 3-methylcholanthrene, on spontaneous mammary tumors in C3H/HEN mammary tumor virus positive mice, and on the rejection of normal tissue transplants at different stages of maturity in C57BL/6 mice. Primary i.m. tumors induced by injection of 3-methylcholanthrene grew slowly over a 3-month period and became acutely necrotic after i.v. injection of rhTNF-alpha (2-6 micrograms). In addition, rhTNF-alpha caused a reduction in tumor area of 24% over 10 days compared to a 43% increase in tumor area in control mice receiving excipient (P2 less than 0.01). Histopathologically, tumors underwent central necrosis with a neutrophilic infiltration as was observed previously for serially transplanted tumors following rhTNF-alpha administration. Spontaneous, virally induced mammary tumors underwent a 11% regression on administration of rhTNF-alpha (4-6 micrograms) compared to a 24% growth in mice receiving excipient (P2 less than 0.05). Normal mice were grafted with syngeneic (C57BL/6) or partially allogeneic (C57BL/10 to C57BL/6) skin and were treated with a single dose of rhTNF-alpha (5-20 micrograms) i.v. at either 5, 10, or 15 days posttransplantation. rhTNF-alpha administration had no effect on the integrity of the skin grafts at any maturation point tested (syngeneic graft survival at 60 days: excipient, 35 of 36 versus 20 micrograms rhTNF-alpha, 35 of 36; allogeneic graft survival: excipient, 46 +/- 8 days versus 20 micrograms rhTNF-alpha, 48 +/- 10 days). In addition, rhTNF-alpha had no effect on the integrity of a syngeneic neonatal s.c. heart graft (graft survival at 60 days, excipient, 35 of 36 versus rhTNF-alpha, 30 of 33). Thus, although rhTNF-alpha administration led to marked necrosis and growth inhibition of vascularized tumor, no effect was observed on vascularized normal tissue transplants. To evaluate possible systemic effects of the tumor bearing state on the maturing neovascularity of normal tissue grafts, the three transplant models were studied in mice bearing a 9-day established MCA-106 s.c. sarcoma. After treatment with rhTNF-alpha (2-6 micrograms), acute necrosis and tumor size reduction was apparent in the s.c. tumors; however, no effect was seen in any of the normal tissue transplants.(ABSTRACT TRUNCATED AT 400 WORDS)     

甲孕酮对改善癌症患者化疗期间生活质量的临床观察

目的为了改善癌症患者化疗期间生活质量。方法1991年12月至1994年12月期间,对30例癌症患者进行了甲孕酮（MPA）治疗的临床观察,设对照组30例。结果口服MPA的癌症患者普遍反映精神、食欲好转,体重有所增加,生活质量综合指数NPS评分较治疗前明显提高（80％,对照组为36．7％,P＜0．01）,伴有痛疼的患者（计18例）的癌痛改善率治疗组为83．3％,显著高于对照组的41％。结论甲孕酮（MPA）可以广泛用于各种肿瘤的化疗期间,来改善患者生活质量。     

醋酸甲羟孕酮对人结肠癌LS174T细胞体内生长抑制的作用

目的检测醋酸甲羟孕酮(MPA)对人结肠癌细胞LS174T移植瘤生长的抑制作用并初步分析其机制。方法建立人结肠癌裸鼠皮下移植瘤模型。随机分为3组,每组10只,对照组:静脉注射或以同等容量的生理盐水灌胃;处理组分为MPA治疗组和MPA+5-Fu治疗组,MPA治疗组:每只每次灌胃MPA30mg/kg;MPA+5-Fu治疗组:每只每次静脉注射5-Fu30mg/kg;每只每次MPA30mg/kg灌胃,MPA灌胃每周5次,5-Fu静脉注射每周3次,共用3周。5周后处死动物,切除瘤灶、称瘤重、测瘤体积、计算抑瘤率;标本用流式细胞仪分析移植瘤细胞周期、凋亡率和细胞表面Fas/FasL表达;免疫组织化学SABC法检测移植瘤组织Fas/Fas-L表达。结果对照组、MPA治疗组、MPA+5-Fu合用组肿瘤体积分别为(1.65±0.68)cm3、(0.78±0.31)cm3、(0.23±0.12)cm3;抑瘤率分别为0、52.7%、86.1%。流式细胞仪分析细胞周期,移植瘤LS174T细胞经MPA处理后阻止G1期细胞向S期的进程,S期和G2/M期细胞相对减少,MPA+5-Fu合用组作用更明显。对照组、MPA治疗组、MPA+5-Fu合用组细胞凋亡率分别为3.6%、13.7%、28.6%,MPA作用后移植瘤LS174T细胞表面Fas和FasL表达显著增强。结论MPA对人结肠癌移植瘤LS174T细胞生长具有显著的抑制作用和诱导凋亡作用,其机制可能与MPA使LS174T细胞停滞于G1期及细胞表面Fas和FasL表达上调有关。     

Modulation of methylcholanthrene-induced carcinogenesis in the uterine cervix of mouse by indomethacin

The present paper reports the chemopreventive action of indomethacin on methylcholanthrene (MCA)-induced carcinogenesis in the uterine cervix of virgin young adult Swiss albino mice. Placement of a sterile cotton thread impregnated with beeswax containing approx. 600 micrograms of MCA produces cervical tumors in 91% mice in 16 weeks. When such carcinogen-containing threads are inserted into the uterine cervix of mice fed diets containing indomethacin at the dose levels of 10 mg/kg, 20 mg/kg and 40 mg/kg diet for two pre-insertion weeks plus 16 post-insertion weeks, the cervical tumor incidences were 83%, 65% and 26% (P less than 0.01), respectively. It is concluded that indomethacin, when given in the diet at sufficiently high concentration, significantly inhibits MCA-induced cervical carcinogenesis.     

Chemopreventive action of mace (Myristica fragrans, Houtt) on methylcholanthrene-induced carcinogenesis in the uterine cervix in mice

The present paper reports the chemopreventive action of mace (aril covering the testa of the seed of Myristica fragrans) on 3-methylcholanthrene (MCA)-induced carcinogenesis in the uterine cervix of virgin, young adult, Swiss albino mice. Placement of cotton-thread impregnated with beeswax containing MCA (approximately 600 micrograms) inside the canal of the uterine cervix results in the appearance of precancerous and cancerous lesions in the cervical epithelium. In this experiment using the cervical carcinogenesis model system, if mace was administered orally at the dose level of 10 mg/mouse per day for 7 days before and 90 days following carcinogen thread insertion, the cervical carcinoma incidence, as compared with that of the control (73.9%), was 21.4%. This decline in the incidence of carcinoma was highly significant (P less than 0.001). The incidence of precancerous lesions did not display any definite association with different treatments.     

Cimetidine enhancement of cyclophosphamide antitumour activity.

Male DBA2 mice were given 10(6) P-388 leukaemic cells i.p. and cimetidine (CMT) at 100 mg/kg 1 day for 10 days, or as a single 100 mg/kg injection 30 min before cyclophosphamide (CTX). CMT significantly prolonged the survival of groups of mice receiving 50, 100 and 200 mg/kg of CTX 3 days after tumour inoculation. Median survival increased by 5.5 days (P less than 0.05), 10 days (P less than 0.05) and 13 days (P less than 0.05) respectively. The addition of CMT had the effect of roughly doubling the CTX dose, without increasing the lethality. CMT produced the only long-term survival seen in the study (1-2/10) CMT alone had no apparent antitumour activity. CMT significantly prolonged mean pentobarbital sleep to 28.6-60 min vs only 10 min for phenobarbital treated mice. Both CMT regimens increased the plasma concentration time products for CTX-induced metabolites (NBP) by about 1.3 fold (in contrast to a 33% reduction with phenobarbital). On average the single-dose CMT regimen produced the greatest effect on survival, on pentobarbital sleep duration and on total NBP reactive species. Probable mechanisms for the CMT-CTX interaction include competitive microsomal enzyme inhibition and/or acutely depressed hepatic blood flow. Caution should be used in combining CMT with full doses of CTX and any other highly metabolized antineoplastic agents in man.     

Cyclosporin A corrects daunorubicin resistance in Ehrlich ascites carcinoma

We have previously developed a daunorubicin resistant subline of Ehrlich ascites carcinoma (EA/DR) for studies on the reversal of daunorubicin resistance. The mean survival of untreated BALB/c mice bearing drug sensitive parental tumour (EA/DS) is 18.4 +/- 0.6 days, mice bearing EA/DS treated with five daily doses of 0.3 mg kg-1 daunorubicin greater than 60 days, and mice bearing EA/DR treated with the same daunorubicin regimen, 21.1 +/- 1.4 days. We now report complete reversal of daunorubicin resistance in EA/DR by cyclosporin A (CsA). The in vitro daunorubicin IC50, defined as that concentration of daunorubicin required to inhibit 50% of DNA synthesis, in EA/DR was 6.7 +/- 1.15 micrograms ml-1 compared to 2.8 +/- 0.72 micrograms ml-1 in EA/DS. This value was reduced to 2.8 +/- 0.52 and 2.1 +/- 0.10 micrograms ml-1 daunorubicin by 3.3 and 13.2 micrograms ml-1 CsA respectively, P less than 0.05. The MST of groups of host mice bearing EA/DR either untreated, treated with five daily doses of 0.3 mg kg-1 daunorubicin, treated with 80 mg kg-1 CsA in five divided daily doses or treated with combined daunorubicin-CsA were 19.0 +/- 1.0, 21.1 +/- 1.4, 24.0 +/- 2.6 and greater than 60 days respectively. The mean survival of groups of host mice bearing EA/DR treated with 5 mg kg-1 or 10 mg kg-1 CsA simultaneously with daunorubicin for five days was also greater than 60 days. These differences are highly significant.     

Selenium and the genesis of murine mammary tumors

One hundred forty-seven female Sprague-Dawley rats were dividedinto 5 groups and at 60 days of age were treated i.g. with 5mg of 7,12-dimethylbenzanthracene (DMBA) suspended in 1.0 mlof sesame oil. Selenium (Se), as selenium dioxide (SeO₂), wasadministered in the drinking water to 4 of the 5 groups (30rats/group) at 2 doses (2 and 4 mg/1) from 30–90 daysof age (series 1) and from 90–150 days of age (series2) prior to the onset of palpable mammary tumors. One groupof rats (27 rats) served as controls. All rats were palpatedweekly for mammary tumors and sacrificed 28 weeks after DMBAtreatment. Total number of palpable mammary carcinomas whichdeveloped in each group were: controls, 60; series 1, 2 mg Sedose, 27, 4 mg Se dose, 29; series 2, 2 mg Se dose, 24, 4 mgSe dose, 32. Each dose level of Se in each series significantly(P <0.05) reduced the incidence of mammary carcinomas. Theseresults provided evidence that Se can inhibit the early promotingphases of polycyclic hydrocarbon induced mammary carcinogenesisin female rats. Two hundred twenty-six nulliparous and 99 multiparousGR mice were treated daily with estrogen and progesterone for13–16 weeks. Se (SeO₂) was administered in the drinkingwater (2 mg/1) to one-half of these mice. Total number of mammarycarcinomas in control nulliparous and multiparous mice were119 and 90, respectively; in Se treated nulliparous and multiparousmice, 113 and 81, respectively. Se did not significantly effectmammary carcinoma incidence in hormone treated nulliparous andmultiparous GR mice.     

Direct inhibiting effects of [D-Trp6]gonadotropin-releasing hormone on the estrogen-sensitive progression of polyoma virus-induced mammary tumors in athymic mice

The direct antitumoral effects of gonadotropin-releasing hormone (GnRH) analogues on breast tumors have been surmised from clinical observations and in vitro studies. The present study aimed to determine the effects of the GnRH agonist [D-Trp6]GnRH (Decapeptyl) on steps of experimental mammary carcinogenesis, and the mechanisms, other than the chemical castration, involved. We chose a recent model, i.e., mammary tumors induced by wild-type A2 polyoma (Py) virus in BALB/c female nu/nu mice, which displays the following characteristics. Tumors are mammary adenocarcinomas similar to well differentiated breast carcinomas. Tumor promotion period ends 20 days after Py virus inoculation and is estradiol dependent. The first palpable tumors occur 60 days after Py virus inoculation, and tumor growth is ovarian hormone independent. The effects of Decapeptyl treatment on tumor induction and tumor growth were studied in normal or ovariectomized 6-week-old nude mice inoculated with 10(7) plaque-forming units Py virus (day 0 of experiments). Normal mice and ovariectomized mice percutaneously supplemented with 0.6 micrograms 17 beta-estradiol every other day until day 30 (OvE2 mice) were treated with monthly s.c. injections of the sustained release form of Decapeptyl (5 mg/kg) until the end of 180-day experiments. Overall values for latency periods were included within a day 60 to day 130 time interval. Hormone-independent outgrowth was not affected. We focused on tumor progression before the outgrowth. Incidences on tumor appearance kinetics account for effects at this stage. 17 beta-Estradiol repletion strongly antagonized (P less than 0.001) the slowing effect of ovariectomy on the tumor appearance kinetics, indicating that tumor progression is estradiol sensitive in its early stages. [D-Trp6]GnRH treatment antagonized tumor appearance profiles, inducing similar kinetics in both normal and OvE2 mice. In normal mice, the antagonism (P less than 0.01) was concomitant with significant decreases (P less than 0.05) in serum levels of estradiol and prolactin, which are critical hormones for mammary tumor development in mice, suggesting a pituitary-mediated effect. In OvE2 mice, the antagonism (P less than 0.01) occurs independently of estradiol and prolactin, suggesting a direct effect at the mammary cell level. Because of alterations in kinetics, this effect is exerted at the early stages of tumor progression on Py virus-transformed, ovarian hormone-sensitive cells in the mammary tissue. This new animal model of breast cancer is shown to be useful in characterizing direct antitumoral effects of GnRH analogues and studying the basic mechanisms of mammary carcinogenesis.     

Mammary carcinogenesis induced byN-methyl-N-nitrosourea (MNU) and medroxyprogesterone acetate (MPA) inBALB/c mice

Summary MPA induces mammary tumors in virgin BALB/c mice with an average latency of 52 weeks. In order to determine whether the simultaneous administration of a chemical carcinogen, N-methyl-N-nitrosourea (MNU), shortened the latency of MPA-induced tumors, a total of 60 virgin female BALB/c mice were treated with either MNU+MPA or MNU or MPA. The experiment lasted 7 months. The incidence and latency of mammary tumors were significantly different between the 3 groups: 15/19 (79%) in MNU+MPA-treated mice with a latency of 154±19 days; 3/20 (15%) in MNU-treated mice with a latency of 179±7 days; 0/20 (tumors only start appearing after 10 months) in MPA-treated mice. Histologically, MNU+MPA-induced tumors were similar to the few tumors observed in MNU-treated mice: most of them were type B adenocarcinomas with a high degree of necrosis and calcification. Only one of the MNU+MPA-induced tumors expressed high levels of ER and PR and proved to be MPA-responsive in further passages. All the other tumors showed low or non-detectable levels of ER and PR together with an independent pattern of tumor growth. In MNU-treated mice the only tumor that was transplanted proved to be hormone independent and had low levels of PR and ER. In both MNU and MNU+MPA treated mice lung adenocarcinomas were detected. Cystic uterine glandular hyperplasias were observed in all animals. It can be concluded that MPA and MNU potentiate their carcinogenic effect in mammary gland.Abbreviations MPA Medroxyprogesterone Acetate - MNU N-methyl-N-nitrosourea - ER Estrogen Receptors - PR Progesterone Receptors     

Recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) given as daily short infusions--a phase I dose-toxicity study

Twenty patients with progressive metastatic solid tumours were entered into a study to evaluate the biological effects and toxicity of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF was given as half-hour intravenous infusions during two 10-day phases of daily treatments (separated by 10 days without GM-CSF) and over a final phase of 20 days of alternate day infusions. Doses were escalated in steps from 0.3 to 60 micrograms kg-1 day-1 between successive patient groups. Significant increases (P less than 0.005) of total leucocyte, neutrophil and eosinophil polymorph counts were seen over the periods of daily infusions (up to four-fold rises of total white count) at dose levels of 10 micrograms kg-1 and above. Counts produced at 30 micrograms kg-1 were significantly higher than at 10 micrograms kg-1 (P less than 0.025). Toxic side effects of GM-CSF included mild transient pyrexias, bone pain and pruritus. The maximum tolerated dose was 60 micrograms kg-1, which produced severe toxicity in 80% of patients. The toxicity at this dose included pericarditis and dyspnoea ascribed to a 'capillary-leak' syndrome. One patient receiving 60 micrograms kg-1 died as a result of a pulmonary embolus. Seven patients with previously rapidly progressive metastatic tumours experienced stabilisation of disease while receiving GM-CSF and one patient with a previously heavily pretreated metastatic soft tissue sarcoma underwent a greater than 50% reduction of tumour volume. Patients undergoing chemotherapy may benefit both from a reduction of the myelosuppressive effects of cytotoxic agents and from an antitumour effect if GM-CSF is incorporated into future regimens.     

Progesterone induction of mammary carcinomas in BALB/c female mice

Summary We have demonstrated that medroxyprogesterone acetate (MPA), when administered in high doses, induces mammary carcinomas in virgin female BALB/c mice. Since one of the possible explanations for this effect was its progestagenic effects, we decided to investigate whether progesterone (Pg) alone could also induce mammary adenocarcinomas in our model and if MPA at doses lower than those used to establish the model was also carcinogenic. A total of 136 mice were subdivided into 3 groups: Group 1, 44 mice were implanted s.c. with 40 mg Pg silastic pellets at the beginning of the experiment, and 6 months later with a 20 mg Pg pellet; Group 2, 45 mice were similarly treated with MPA pellets; Group 3, 47 mice were inoculated s.c. with 40 mg MPA every three months. At the end of 20 months, 9 animals had developed mammary tumors in Group 1, 18 in Group 2 and 34 in Group 3 (actuarial incidence = 28%, 58%, and 98%, respectively); tumor latency was similar in all groups: 46.2 ± 13.1, 51.3 ± 9.9, and 50.1 ± 2.1 weeks, respectively. Seven (Group 1), 14 (Group 2), and 25 (Group 3) tumors were transplanted into syngeneic mice to determine progestin dependence. All tumors, except one from Group 1, were histologically characterized. In Group 1 (Pg 60 mg), 4 tumors (67%) were infiltrating lobular carcinomas and 2 were ductal carcinomas (33%). In Group 2 (MPA 60 mg), 2 tumors (14%) were lobular and 12 were ductal adenocarcinomas (86%) (Group 1 vs Group 2: p < 0.05), whereas in Group 3 (MPA 160 mg), 8 were lobular carcinomas (32%) and 17 were ductal carcinomas (68%). In syngeneic passages all lobular tumors behaved as progestin independent (PI) and ductal tumors as progestin dependent (PD). All ductal tumors, except one, expressed estrogen receptors (ER) and progesterone receptors (PR), whereas receptor expression was variable in lobular carcinomas. It can be concluded that Pg induces mostly lobular, PI mammary tumors in BALB/c female mice. The fact that most MPA-induced tumors are ductal and PD suggests that the two hormones use different carcinogenic pathways.     

Effect of moderate vitamin A supplementation and lack of dietary vitamin A on the development of mammary tumors in female rats treated with low carcinogenic dose levels of 7,12-dimethylbenz(a)anthracene

We examined the effect of moderately increased and of marginal continued dietary supplementation of vitamin A (retinyl acetate) and the effect of lack of dietary vitamin A on the initiation and promotion stages of mammary tumorigenesis in female Sprague-Dawley rats treated with a single low (0.5 mg/100 g body weight) or very low (0.1 mg/100 g body weight) dose of i.v.-administered 7,12-dimethylbenz(a)anthracene. The number of mammary tumors was significantly (P less than 0.05) reduced if prior to and during initiation with 7,12-dimethylbenz(a)anthracene the rats were fed a moderately increased (30 micrograms/day) or marginal (3 micrograms/day) amount of vitamin A, compared to rats fed an adequate (10 micrograms/day) amount of vitamin A. The number of mammary tumors was also significantly (P less than 0.05) reduced when a moderately increased or marginal amount of vitamin A was provided during the tumor promotion phase. In addition, the number of mammary tumors was significantly (P less than 0.05) reduced by the lack of dietary vitamin A during both the initiation and promotion stages of this tumorigenic process, when compared to vitamin A adequate, ad libitum-fed rats, but not when compared to vitamin A adequate, food-restricted controls. The reduction in numbers of mammary tumors observed in these studies was reflected primarily in significant (P less than 0.05) decreases in mammary fibroadenomas; the number of mammary carcinomas was often reduced, but due to a low frequency of the carcinomatous lesions, this reduction did not reach the 5% level of statistical probability. Plasma and liver vitamin A levels were determined during both the initiation and promotion stages. As the dietary supplementation of vitamin A increased from 0 to 30 micrograms/day, there was an increase in mean liver and plasma vitamin A levels. No consistent correlation between plasma and liver vitamin A levels and the occurrence of mammary tumors was observed, except with the moderately increased (30 micrograms/day) intake of vitamin A, that resulted in a small, but statistically significant (P less than 0.05) increase of serum retinol at initiation; this may account for the observed reduction in mammary tumors. These results provide evidence that moderate alterations in vitamin A consumption can modulate low-dose chemically induced mammary gland tumorigenesis. Most importantly, suppression of mammary gland tumorigenesis can be achieved by moderately increased, frequent, and regular consumption of vitamin A; prolonged consumption of vitamin A-deficient diets or diets marginal in vitamin A does not enhance the risk of mammary tumor development.     

Modification of tumor promotion in the mouse skin by exposure to an alternating magnetic field.

Some epidemiological studies have suggested that exposure to an alternating magnetic field may increase the incidence of some cancers. Our earlier study of carcinogenesis in mouse skin, indicated that exposure to a magnetic field (MF) alone did not promote the growth of tumors. In the present experiment, the ability of a MF to act as a tumor copromoter was investigated. The dorsal skins of female SENCAR mice (6-7-weeks-old) were treated with 10 nmol of 7,12-dimethylbenzanthracene (DMBA) to initiate the carcinogenic process and then tumor development was promoted, for 23 weeks, by weekly applications of 4.9 nmol (0.3 microgram) of 12-0-tetradecanoylphorbal-13-acetate (TPA). One group of 48 mice were exposed to a 60-Hz magnetic field of 2 mT (20 Gauss) for 6 h/day 5 days/week, while a similar group (48 mice) were sham exposed. After week 12, the percentage of mice with tumors and the mean number of tumors per mouse, were higher for the group exposed to MF. At week 18, for example, where the differences between field and sham groups were statistically significant, the percentage of mice with tumors were, respectively, 25% and 8% (P less than 0.05, Fisher exact) and, the mean yield of tumors 1.9 +/- 0.69 and 0.65 +/- 0.46 (mean +/- S.E.M.) (P less than 0.05, Wilcoxon). At week 23 these differences were no longer statistically significant.     

Augmentation of antitumor efficacy by the combination of recombinant tumor necrosis factor and chemotherapeutic agents in vivo

We evaluated the in vivo antitumor effects of the combination of recombinant human tumor necrosis factor (rhTNF) and three chemotherapeutic agents in an established murine tumor model. C57BL/6 mice bearing a subdermal weakly immunogenic 3-methylcholanthrene-induced sarcoma (MCA-106) received one i.v. dose of cyclophosphamide (Cy) (100 mg/kg), doxorubicin (5 mg/kg), or 5-fluorouracil (75 mg/kg) on either Day 8, 10, or 12. All animals received one i.v. dose of rhTNF (4 or 6 micrograms/mouse) on Day 10. The most effective time for administration of the chemotherapeutic agent was determined to be 48 h following rhTNF administration of all agents tested. The combined results of four separate experiments evaluating tumor size on Day 28 following tumor inoculation revealed that the groups treated with 4 or 6 micrograms of rhTNF and Cy (on Day 12) had tumor size reductions of 70 and 94%, respectively, compared to untreated controls (P2 less than 0.005). Mice treated with Cy alone, or with 4 or 6 micrograms of rhTNF alone had tumor size reductions of 30, 35, and 41%, respectively, compared to untreated controls (P2 less than 0.02). Analysis of cure rates demonstrates that the combination of Cy with 4 or 6 micrograms tumor necrosis factor cured 35 and 48% of the animals, respectively (P2 less than 0.01), compared to 10, 0, and 14% of mice treated with single agent Cy, 4 micrograms rhTNF, or 6 micrograms rhTNF, respectively. The timing of Cy and TNF administration was critical since administration of Cy prior to or concurrent with rhTNF was not effective in reducing tumor area or increasing cure rates over those achieved with either agent alone. Mice treated with doxorubicin alone had an increase in tumor size of 139 +/- 29% over untreated controls (P2 less than 0.05) on Day 28 following tumor inoculation and none were cured. In contrast, mice treated with doxorubicin plus 4 or 6 micrograms rhTNF exhibited early reductions in tumor size such that on Day 28 the average tumor areas were decreased by 66 +/- 34% (P2 less than 0.05) and 73 +/- 1% (P2 less than 0.02) of untreated controls with cure rates of 29% and 43% (P2 less than 0.02), respectively. However, the combination of 6 micrograms rhTNF plus doxorubicin led to substantial lethal toxicity with only 29% of mice surviving treatment. 5-Fluorouracil alone resulted in an increase in tumor area of 164% (P2 less than 0.05) over that of untreated controls on Day 28 following tumor inoculation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Doxorubicin: monoclonal antibody conjugate for therapy of human cervical carcinoma.

Doxorubicin (Dox) was conjugated via a dextran linker to the F(ab')2 fragment of monoclonal antibody (MAb) 1H10 which recognizes an antigen expressed on the surface of human cervical carcinoma cells and tissues. Drug-antibody conjugates (1H10-Dox) with a molar ratio of Dox to MAb ranging from 40:1 to 60:1 retained antigen-binding and pharmacological activities. Anti-tumor activity of the conjugate in vitro was evaluated by measuring inhibition of [5-3H]-uridine incorporation into cellular RNA. 1H10-Dox was found to be 30 times more toxic to cervical tumor cells than a control MAb-Dox conjugate and 150 times more potent than Dox coupled to dextran. In addition, 1H10-Dox was less toxic to antigen-negative cells in vitro, suggesting that 1H10-Dox killing of cervical carcinoma cells was antibody-mediated. 125I-labeled 1H10-Dox preferentially localized in solid human cervical carcinoma xenografts in athymic mice with tumor-to-blood ratios of 1H10-Dox reaching 17.9 after 24 hr and 32.8 after 48 hr. Treatment of athymic mice bearing human cervical tumors with 1H10-Dox resulted in a dose-dependent inhibition of tumor growth. Multiple administrations of 1H10-Dox at a dose corresponding to 20 micrograms doxorubicin significantly suppressed the growth of human cervical tumors in nude mice without significant side effects (weight loss), and this suppression was antibody specific. Both i.p. and i.v. administration of 1H10-Dox were found to be equally effective. Our results suggest that 1H10-Dox may be useful for the treatment of human cervical carcinoma.     

Development of a xenograft glioma model in mouse brain

Xenograft intracerebral glioma models have been developed in normal mice by growing the rat C6 glioma in either adult or neonatal mouse brains. Using this tumor line it was possible to grow discrete intracerebral gliomas in either CBA or AKR adult mice or neonatal mice. The size of the tumor mass and length of survival was directly related to the number of tumor cells injected and the time after implantation. To obtain localized intracranial tumor growth cells were suspended in a 1% agarose solution before implantation. Following injection of 10(6) cells into the frontal lobe of adult CBA or AKR mice, discrete tumor masses greater than 4 mm in diameter were obtained in 90% of animals at 14 days, and the largest tumors in adult mice occurred between 21 and 28 days after implantation. The tumor size following implantation of 10(6) cells was significantly greater than with 10(5) cells at 7 days (P less than 0.05) and at 14 and 21 days (P less than 0.01). Less than 60% of mice of BALB/c, RIII, or C57 black strains developed tumors greater than 4 mm diameter at 14 days after intracerebral injection of 10(6) C6 cells. Using neonatal mice it was found that when 10(5) cells were injected intracranially tumors greater than 4 mm in diameter developed in 14 of 15 animals within 2 weeks (CBA mice). Similar results were seen in the RIII, AKR, C57 black, and BALB/c strains. Longer growth periods resulted in larger tumors, up to 8 mm in diameter (6 of 10 animals at 20 days). The tumors in the neonatal animals were not as discrete as in the adult mice, and tumor often spread to the meninges and into the lateral ventricles. The tumor harvested from the brain had a cloning efficiency of 1.2 +/- 0.4% (SD). A panel of monoclonal antibodies was raised to the C6 glioma, and this was used to define clearly the margins of the tumor within the brain. The xenograft mouse models should prove useful for the study of the therapy of gliomas.