Metastatic Growth of a Murine Tumor: Evidence of Dissemination to the Lungs in the Absence of Subcutaneous Growth

Growth of MCA-38/B colon adenocarcinoma was detectable 30-33 days after subcutaneous (s.c.) tumor cell inoculation in mice. Seventy percent of the mice receiving 107 tumor cells, 50 % of those receiving 104, and 15% of the mice given 105 cells developed s.c. tumors (mean of 4 experiments, total of 80 mice per group). Metastases in the presence of a primary tumor were observed in 11% of 107 and in 10% of 106 tumor-cell injected animals. Lung metastases were detected in the absence of tumor growth at the site of s.c. cell injection in 19% of 107, in 8% of 106 and in 5% of 105 and 104 tumor-cell inoculated mice. In parallel experiments an intravenous (i.v.) inoculum of tumor cells produced lung colonies in 40% of 106 and in 14% of 105 tumor-cell injected animals. Smaller inocula did not give rise to lung colonies, thus making it unlikely that accidental i.v. inoculations of tumor cells during the s.c. injections caused the observed metastatic dissemination to the lungs.

Antitumor activity of 1,4-bis (2'-chloroethyl)-1,4-diazabicyclo-[2.2.1] heptane dimaleate (Dabis Maleate) in M5076 and its subline resistant to cyclophosphamide M5/CTX

We investigated the antitumoral activity of Dabis Maleate given on different dosage schedules and as continuous infusion in a murine reticular cell sarcoma M5076 (M5) and in a subline made resistant to cyclophosphamide and other nitrogen mustards (M5/CTX). The therapeutic index of Dabis Maleate was clearly better when the drug was given as a continuous 72-h infusion. Dabis Maleate appeared non-cross-resistant to cyclophosphamide and this property renders it interesting for further clinical development.

Method for kinetic analysis of drug-induced cell cycle perturbations

A method is described for quantitative study of the flux of cells through the cell cycle phases in in vitro systems perturbed by chemicals, such as chemotherapeutic agents. The method utilizes cell count and the flow cytometric technique of bromodeoxyuridine (BrdUrd) labeling, according to an optimized strategy. Cells are exposed to BrdUrd during the last minutes of drug treatment and fixed for analysis at 0, 1/3Ts, 2/3Ts, Ts, and Tc + TG1 recovery times, where Ts, TG1, Tc are the mean durations of phases S and G1 and of the whole cycle of control cells. As an example of application of the proposed procedure, a kinetic study of the effect of 1-(2-chloroethyl)-1-nitrosourea (CNU) on the L1210 cell cycle is described. Simple data analysis, requiring only a pocket calculator, showed that cells in phases G1 and G2M at the end of a 1 h treatment with 1 microgram/ml CNU were fully able to leave these phases but were destined to remain blocked in the following G2M phase (G1 for a minority of them). We also found that cells initially in S phase were slightly delayed in completing their S phase and that 50% of them remained temporarily blocked in the subsequent G2M phase, irrespective of their position in the S phase.

O6-methylguanine and temozolomide can reverse the resistance to chloroethylnitrosoureas of a mouse L1210 leukemia

Using L1210 and a subline resistance to chloroethylnitrosoureas (L1210/BCNU), we found that the resistance to 1-(2-chloroethyl)-1-nitrosourea (CNU) or to diethyl-1-3-(2-chloroethyl)-3-nitrosoureido ethyl phosphonate (fotemustine) can be reversed by a pretreatment with O6-methyl Guanine (O6-mGua) or temozolomide. In L1210/BCNU but not in L1210 the pretreatment with O6mGua caused an increased peak level of CNU-induced DNA-interstrand crosslinks. We then evaluated whether the resistance to BCNU could be counteracted in vivo by i.p. O6mGua treatment of L1210/BCNU bearing mice. The results were negative due to the fact that O6mGua, which was not toxic when given alone, caused a high toxicity when associated with BCNU.

Temozolomide induced differentiation of K562 leukemia cells is not mediated by gene hypomethylation

Temozolomide (8-carbamoyl-3-methylimidazo[5,1d]-1,2,3,5-tetrazin-4-(3H)-one), an experimental antitumor agent which spontaneously decomposes to 5-(3,3-methyl-1-triazeno) imidazole-4-carboxamide, the active metabolite of the antineoplastic drug DTIC, causes erythroid differentiation of K562 leukemia cells. The increase in epsilon and gamma globin gene expression after temozolomide treatment does not appear to be due to drug-induced hypomethylation of the genes. In other genes containing many methylated sequences such as the proto-oncogenes c-myc and C-Ha-ras, temozolomide caused no detectable change in methylation. In contrast, in the same genes 5-aza-2'-deoxycytidine induced hypomethylation. Temozolomide caused DNA alkali-labile sites and an arrest of the cell cycle in G2 phase. Ethazolastone (its 3-ethylimidazo analogue) which does not cause differentiation of K562 produced no significant DNA damage and G2 phase blockade. DNA damage rather than hypomethylation may be responsible for induction of differentiation.

Antitumor activity of the novel nitrosourea S10036 in rodent tumors

The activity of the novel anticancer agent diethyl 1-3-(chloroethyl)-3-nitrosoureido ethyl phosphonate (S10036) was investigated on several rodent tumors. S10036 showed a good efficacy, comparable to that of the anticancer agent BCNU, against i.p transplanted P388 and L1210 leukemias. S10036 was very effective against the primary tumor and metastases of i.m transplanted M5076 reticular cell sarcoma of the mouse and against subline A of the Walker carcinoma of the rat. It was inactive against rodent tumors resistant to BCNU such as L1210/BCNU, ICIG-Ci4 murine fibrosarcoma and the Walker carcinoma subline B in the rat.

Influence of gangliosides on primary and metastatic neoplastic growth in human and murine cells

The influence of gangliosides on tumor growth and frequency of metastasis in vivo as well as on growth and motility of neoplastic cells in vitro was tested utilizing human and rodent cell populations. In mice receiving injections of a ganglioside mixture twice daily the tumor volume, the number of spontaneous metastases per animal, and the number of mice with metastasis was approximately double that of controls. Preincubation of neoplastic cells with the ganglioside mixture doubled the number of metastatic foci in the lungs of mice receiving the cells by i.v. injection. Addition of a ganglioside mixture to the culture medium enhanced motility of neoplastic cells about 3-fold. This finding was similar to that observed for capillary endothelium. The presence of gangliosides in the culture media for a 48-h incubation period about doubled the number of neoplastic cells as compared to controls; the same was observed for capillary endothelium. The data are interpreted to indicate that gangliosides improve growth and mobilization of capillary endothelium and neoplastic cells. Both events may concur in enhancing tumor growth in vivo, the first by improving angiogenesis, the second by direct action on the neoplastic cell population.

2,2'-Bipyridyl-6-carbothioamide derivatives as potential antitumor agents

4- and/or 4'-substituted 2,2'-bipyridyl-6-carbothioamides have been synthesized and tested for their activity against P-388 lymphocytic leukemia in mice. Of these, only 4'-nitro-2,2'-bipyridyl-6-carbotioamide (IV c) proved to be active.

Immunological profile of DL111-IT, a new immunosuppressant agent

The immunosuppressive properties of the non-hormonal contragestional agent 3-(2-ethylphenyl)-5-(3-methoxyphenyl)-1H-1,2,4-triazole (DL111-IT) were evaluated on different immunological functions. The compound displayed significant immunosuppressive activity on both humoral and cellular immunity when administered during the inductive phase of the immune response. In experimental models autoimmunity and skin transplantation, DL111-IT was able to reduce the production of auto-antibodies and prolong skin graft survival. The compound, even at doses much higher than those effective inhibiting immune responses, did not influence the survival time of some haematological tumors in mice. This suggest that DL111-IT does not act by a general cytotoxic mechanism.

Caffeine distribution in acute toxic response among inbred mice

The median lethal dose (LD50) and the median lethal concentration (LC50) of caffeine administered intravenously (i.v.) and orally (p.o.) were calculated in adult male CD2F1/Crl BR mice. Acute toxic behavioral responses to the drug were observed after administration via the two routes. Deaths followed severe tetanic convulsions: some animals had transient convulsions and survived, and others presented no acute toxicity. In a further study, the LD50 of caffeine was given i.v. and by gavage to animals randomly paired. At the death of one of the two mice the other was killed and caffeine assayed in blood and tissues of both. Different patterns of distribution were observed inter- and intra-route of administration, animals which died always having higher drug levels, although they had received the same dose. These findings suggest that besides the well-known factors affecting acute toxic response to exogenous compounds, drug distribution also has to be taken into account in a multifactorial toxicological investigation.

The antineoplastic activity of 4'-deoxydoxorubicin in murine solid tumors

The antineoplastic effectiveness of 4'-Deoxydoxorubicin (DeDXR), a novel anthracycline with reduced cardiotoxicity, has been compared with that of Doxorubicin (DXR) in a panel of murine solid tumors of different histo-type, growth rate, and metastatic behaviour. Using doses of comparable toxicity and optimal treatment schedules, DeDXR was more active in the RC2 renal carcinoma, mFS6 fibrosarcoma, and Madison 109 carcinoma models, as judged by effects on primary and secondary tumor growth inhibition, increase in survival and/or proportion of tumor-free animals. In the M5076 reticulosarcoma DeDXR was equally effective with DXR, whereas the latter was more active on the PRSCT-5 prostate tumor.

Effects of disodium etidronate in murine tumor models

This study was designed to elucidate the effect of ethane-1-hydroxy-1,1-diphosphonate (EHDP) in experimental rodent tumors. EHDP had no antitumor activity against the L1210 leukemia implanted i.p. and against sarcoma 180, Lewis lung carcinoma (3LL) and Walker 256/B carcinoma injected i.p., s.c. or i.m. respectively. EHDP did not interfere with the antitumor activity of commonly used conventional chemotherapeutic agents (adriamycin, cyclophosphamide, 5-fluorouracil, bis-chloroethylnitrosourea) in the L1210 and 3LL models. EHDP reduced proportionally to the dose the hypercalcemia and hypercalciuria due to the Walker 256/B carcinoma growth. In an effort to evaluate whether EHDP-treated osseous tissues were more refractory to tumor growth, cells from sarcoma 180 and 3LL carcinoma were implanted intratibially (i.t.). Growth of 3LL cells was not consistently affected by EHDP, whereas a modest, but significant, growth inhibition was consistently observed with sarcoma 180 injected i.t. Growth of sarcoma 180 implanted i.p. or s.c. was not reduced by this drug, thus suggesting that inhibition of i.t. sarcoma 180 was in fact related to alterations of osseous tissues by EHDP. Inoculation of Walker 256/B carcinoma intra-aortically resulted in osteolytic bone lesions in the hind limbs. EHDP inhibited the formation of bone metastasis under these conditions.

The antineoplastic activity of hexaziridinocyclotriphosphazene (Myko 63) in murine tumors

The antineoplastic activity of hexaziridinocyclotriphosphazene (Myko 63) has been investigated in a panel of murine ascitic and solid tumors. Myko 63 was found to significantly retard primary and secondary tumor growth and to prolong the survival rates in each of the nine models employed. These included the L1210 and P388 leukemias, P815 mastocytoma, the 3LL and Madison 109 carcinomas, M5076 reticulum cell sarcoma, the line 26 colon and line 16 mammary carcinomas, and an intracranially implanted ependymoblastoma. The possible modes of action of this compound and the potentials of cyclophosphazenes, a chemical class largely unexplored as antitumor agents are discussed.

In vitro and in vivo cytotoxicity of possible uracil metabolites of methylxanthines

The present study was designed to elucidate the cytotoxic potential of 8 possible substituted uracilic metabolites of methylxanthines. 5-Fluorouracil (5-FU) was used as a reference uracil analogue with cytotoxic activity. Substituted uracil derivatives examined in this study did not affect the proliferative capacity of PHA-stimulated rat lymphocytes, murine L1210 leukaemia and rat chondrocytes. Caffeine had some growth inhibitory activity of extremely high concentrations (greater than 100 micrograms/ml). In vivo administration of 6-amino-5[N-methyl-formylamino]1,3-dimethyluracil (1,3,7-TAU) and 6-amino-5[N-acetylamino]3-methyluracil (7-A3-MAU) caused a transient short-lived reduction of L1210 tumour cell numbers. These observations do not appear to support the hypothesis that substituted uracils are involved in the toxicity of high doses of caffeine in rats.

The immunomodulatory activity of the plant proteins Momordica charantia inhibitor and pokeweed antiviral protein

The immunological activity of Momordica Charantia inhibitor (MCI) and of Pokeweed antiviral protein (PAP-S), 30,000 daltons plant proteins possessing close similarity to Ricin A chain as inhibitor of protein synthesis, was investigated in mice. In vivo, single nontoxic injections of microgram amount of these substances delayed H2-incompatible skin allograft rejection, splenocyte responsiveness to ConA and PHA, but not to LPS, and abrogated the PFC response to a T-dependent (SRBC) antigen while totally sparing that to a T-independent (S III) stimulus. Injection of these substances could also reduce NK cell activity while increasing macrophage-mediated spontaneous cytotoxicity. In vitro, MCI and PAP-S at non-cytotoxic concentrations inhibited lymphoid cell responsiveness to PHA and ConA, but not to LPS, and markedly enhanced macrophage-dependent cytotoxicity.

In vitro and in vivo cytotoxicity of 6 amino-5-formyl-methylamino-1,3-dimethyl uracil, a uracilic metabolite of caffeine

The in vitro cytotoxicity of 6 amino-5 formylmethylamino-1,3 dimethyluracil (ADMU) a major metabolite of caffeine in rats was studied by cell counts or [3H]thymidine incorporation in the murine Lewis lung carcinoma (3LL) and L929 fibroblast cells and in the human E cell line derived from an ovarian carcinoma. Unlike 5-fluorouracil (5FU) which was markedly cytotoxic, ADMU concentrations up to 60 micrograms/ml were devoid appreciable cytocidal action. Similarly, 1-10 micrograms 5FU markedly inhibited the blastogenic response of rat lymphocytes to PHA, whereas lymphoproliferation was not affected at ADMU concentrations up to 100 micrograms/ml. In vivo administration of ADMU (40 mg/kg, twice a day on day 1 to 3) to L1210 leukaemia-bearing mice caused a transient short-lasting reduction of tumour cell numbers only on day 6 after leukaemia inoculation.U

Effect of medroxyprogesterone acetate on DMBA-induced rat mammary carcinoma and on immunological reactivity

The antineoplastic activity of medroxyprogesterone acetate (MPA) was investigated in rats bearing DMBA-induced mammary carcinomas, a classical model of hormone-dependent tumor. Using a repeated injection schedule of relatively short duration, MPA was markedly effective (80% CR + PR) not only on relatively small (1-1.5 cm) tumors but also on advanced (4.5-5.5 cm) neoplasms. MPA effectiveness was comparable to that of a frankly toxic adriamycin regimen. In antitumorally effective schedules MPA was incapable of significantly affecting in either direction cellular and humoral immunological reactivities in rodents.

A characterization of the activity of alpha-1,3,5-triglycidyl-s-triazinetrione, a novel antineoplastic compound

To extend initial results on the antineoplastic activity of alpha-1,3,5-triglycidyl-s-triazinetrione (TGT, NSC 296934), a novel triepoxidic derivative, this compound was tested in a series of murine transplantable tumors. Repeated daily treatments with well-tolerated systemic doses of this chemical produced substantial retardation in tumor growth and significant prolongation of survival in the line 16 mammary, M5067 ovarian, and Madison 109 lung carcinomas and in mFS6 fibrosarcoma. Very marked activity was also seen in the P815 mastocytoma, B16 melanoma, line 38 colon carcinoma, and an intracerebrally transplanted ependymoblastoma, with high proportions of cures after one or two injections in IP transplanted SL2 lymphoma and line 26 colon carcinoma. It is concluded that the high level of antineoplastic effectiveness and the wide spectrum of TGT activity together with its novel structural characteristics could be of clinical significance.