Effect of OK-432 on the lymphnode metastasis of MCA-sarcoma cell lines: a new therapeutic approach.

The two unique highly metastatic MCA-sarcoma cell lines have been established by the present authors. The inoculation of 1153Ln, one of the cell lines, either into footpad or subcutaneously on the back of syngeneic mice resulted in the development of metastasis exclusively in almost all lymphnodes of the body. We evaluated the therapeutic effect of a streptococcal preparation, OK-432, on the lymphnode metastasis. Two KE per mouse of OK-432 were injected intratumorally (it) at 4, 7 or 10 days after the footpad inoculation of 1153Ln. OK-432 injected it at 7 days after tumor inoculation showed an inhibition of the lymphnode metastasis. Histological findings indicated that the proliferation of lymphoid cells in the drainage node was most prominent in mice treated with OK-432 at 7 days after the tumor inoculation. A combined treatment of it and intraperitoneal (ip) injections of OK-432 significantly reduced lymphnode metastasis as compared with that of ip injection alone. This can be attributed to the fact that the activated lymphocytes induced by it-injected OK-432 exhibited a potent antimetastatic activity together with general administration (ip) of OK-432 given after surgical removal of the tumor. Low dose of total-body irradiation (TBI), known to augment the antitumor potential of tumor-bearing animals together with general application of OK-432, showed synergistic action in inhibiting tumor growth. Overall results suggest that the better antitumor effect of OK-432 can be anticipated by combination of the agent itself and with other means.

Carcinogenic and co-carcinogenic effects of radiation in rat mammary carcinogenesis and mouse T-cell lymphomagenesis: a review.

The importance of the promotion stage and of the physiological condition of target cells at the time of initiation is illustrated in both the rat mammary carcinogenesis and the mouse T-cell lymphomagenesis. In the former, prolactin was shown to be a powerful promoter regardless of the initiating agent. Prolactin was also found to be useful in detecting the carcinogenicity of the small doses of carcinogens; a high r.b.e. of 2.0 MeV fission spectrum neutrons was demonstrated by the application of prolactin to radiation-initiated mammary carcinogenesis in rats. In the latter, total-body irradiation involving both bone marrow and thymus facilitates chemically-initiated T-cell lymphomagenesis in mice. This could be attributed to the amplification of the cell population susceptible to a chemical carcinogen in the target tissue during the recovery phase after irradiation. The dual effect of a carcinogen, acting in the different phases of carcinogenesis was suggested by the split administration of N-nitrosoethylurea (NEU) in the induction of T-cell lymphomas. It is emphasized, through these findings, that besides the initiation by a genotoxic agent, the availability of a promoter or an inhibitor determines the fate of initiated cells, and that a modifier of target cells also plays a crucial role in the efficient induction of a tumour.

Induction of hepatic tumors by diethylstilbestrol in N-nitrosobutylurea-initiated female rats.

The carcinogenic effect of estrogens, diethylstilbestrol (DES) and 17 beta-estradiol (E2), and its modification by N-nitrosobutylurea (NBU) were studied in female W/Fu rats. Multiple mammary tumors (MT) of medullary carcinoma type developed at a high rate following prolonged treatment with estrogens. All MTs were located adjacent to the nipple and were slow-growing. The induction rate, multiplicity and size of estrogen-induced MTs were not influenced by pretreatment with a small amount of NBU, which alone did not induce any tumor. Ten of 12 rats (82%) receiving combined treatment with NBU and DES developed hepatic tumors (HT), while no rats in other treatment groups developed HT. All HTs were multiple nodules of various sizes bulging from the liver surface, and were considered to be neoplastic nodules. A high frequency of HT development was unexpected, because independent treatment with NBU or DES alone did not induce HT in female rats. It appears that DES played a role as a carcinogen, inducing MT and pituitary tumor (PT) through its estrogenic potency (like natural estrogen, E2), while it also acted as a promoter or co-carcinogen in the induction of HT through its pharmacologic effects. These findings may be relevant to an increased frequency of liver neoplasm among women taking oral contraceptives containing synthetic estrogens.

Protective effects of progesterone and tamoxifen in estrogen-induced mammary carcinogenesis in ovariectomized W/Fu rats.

The protective effect of progesterone or tamoxifen, an antiestrogenic agent, was investigated in estrogen-induced mammary carcinogenesis. Multiple mammary tumors (MT) of tubular or medullary carcinoma type developed at a high rate following prolonged treatment of ovariectomized W/Fu rats with diethylstilbestrol or 17 beta-estradiol. All MTs were located adjacent to the nipple and were slow-growing. The induction rate, multiplicity and size of estrogen-induced MTs were reduced by the simultaneous administration of either progesterone or tamoxifen. The estrogen-induced pituitary tumorigenesis was effectively inhibited by tamoxifen treatment, but it was not affected by progesterone. The results indicated that the inhibitory effect of progesterone or tamoxifen in estrogen-induced carcinogenesis is attributable to interference with the binding of estrogen to the estrogen receptors on the target cells.

High mammary carcinogenicity of neutron irradiation in rats and its promotion by prolactin.

The present study was undertaken to assess the mammary carcinogenic effect of low doses of fission and thermal neutrons in female W/Fu rats. Only 2 of 62 (3.2%) rats exposed to various doses of fission radiation alone developed mammary tumors (MT) in a 12-month observation period, whereas 21 of 63 (33.3%) similarly irradiated rats developed MT if further treated with prolactin; the lowest effective dose was 4.1 rad, which contained only 1.7 rad of fission spectrum neutrons with an average energy of 2.0 MeV. The long survival of radiation-initiated potentially malignant cells was suggested by the observation that excess numbers of MT developed in irradiated rats in whom prolactin treatment was started as late as 12 months after irradiation. The negligible contribution of gamma-rays, one component of the reactor radiations, to the rat mammary carcinogenesis was proven by a simulation experiment with 60Co gamma-rays. Thermal neutrons with an average energy of 0.025 eV were less effective than fission neutrons. The rat mammary carcinogenic effects of 180 kVp X-rays, 14.1 MeV fast neutrons, 0.025 eV thermal neutrons and 2.0 MeV fission neutrons were estimated in such a way as to compare the dose of each radiation that gave an MT incidence of 40% of that in irradiated, prolactin-treated rats. The efficiency of fission spectrum neutrons is much higher than those of other radiations; the relative biological effectiveness (RBE) of fission spectrum neutrons was 17.8 against X-rays. Based on these findings, the relevance of animal data to tumor induction in atomic bomb survivors is discussed.

Generation of lymphomagenic mouse type-C viruses from radiation- or chemically-induced non-producer T-cell lymphoma cell lines infected with non-oncogenic ecotropic virus.

Highly lymphomagenic mouse type-C viruses were generated from radiation- or chemically-induced T-cell lymphoma cell lines of NFS/N mouse origin infected with a non-oncogenic ecotropic virus E4. By analysis of these progeny viruses, the following results were obtained. 1) The viruses were lymphomagenic in neonatally inoculated NFS/N and C3H/He mice and W/Fu rats but not in Balb/c and C57BL/6N mice, indicating that they possess the Fv-1n tropism of exogenously infected parent virus. 2) Lymphomagenic viruses consisted of plural viral subpopulations. Recombinant mink cell focus-inducing (MCF) and ecotropic viruses were cloned from them. Inoculation of either MCF or ecotropic virus alone or both viruses together did not cause lymphoma in NFS/N mice and there was no evidence of viral replication in the recipients. 3) Inoculation of either MCF- or ecotropic virus-infected NFS-ME cells alone did not cause lymphoma development in pre-irradiated NFS/N mice, while transplantation of both MCF- and ecotropic virus-infected NFS-ME cells resulted in the development of lymphomas of host origin. These results show that lymphomagenic MCF virus was generated through the recombination of E4 viral genome and a modified proviral DNA of endogenous viruses present in radiation- or chemically-induced lymphomas, and that an interaction or synergism of MCF and ecotropic viruses is required for MCF virus to exert lymphomagenic activity.

Synergistic effect of radiation and N-nitrosoethylurea in the induction of lymphoma in mice: cellular kinetics and carcinogenesis.

The effect of a combined treatment with radiation and N-nitrosoethylurea (NEU), or a split administration of NEU in inducing lymphoma was studied in female C57BL/6N mice. A single intragastric administration of 5 mg of NEU was only slightly lymphomagenic, inducing thymic lymphomas in 20% of mice, while the incidence was elevated to 92% if the NEU treatment was preceded (by 5 days) by 400 rad of total-body X-irradiation, which alone is seldom lymphomagenic. A high yield of lymphoma (84-93%) was also obtained if 5 mg of NEU was delivered in two split doses of 4 mg and 1 mg with a 4 day interval. Drastic injury to both the thymus and bone marrow caused by either 400 rad total-body X-irradiation or the first dose of NEU (4 mg) was followed by a vigorous regeneration within a few days. The maximum induction rate of lymphoma was obtained when the subsequent dose of NEU (1 mg) was given at the peak of DNA synthesis in the bone marrow and thymus following the first treatment. The data indicate that the principal effect of the irradiation or the first dose of NEU was to provide a susceptible cell population, and that a high yield of lymphoma was brought about through the action of the subsequent dose of NEU on a sufficient number of target cells engaged in heightened DNA synthesis.

Treatment of congenital dilatation of the choledochus- reconstruction of the bile duct after resection of the dilated choledochus.

Reconstruction of the way of bile flow was attempted in 21 cases with the resection of the dilated bile duct, and the post-operative courses were observed over a long period. It was found that ascending cholangitis is seldom caused by the hepaticoduodenostomy. It is important, when hepaticoduodenostomy is performed, that the sound section of the wall of the bile duct without stenosis in the hepatic side should be selected. Reconstruction of the way of the bile flow to prevent ascending cholangitis by leading normal bile flow into the duodenum should be devised.