The sera of normal rats were found to be active in the complement fixation test against isogeneic tumour homogenates. This activity was shown to be heat labile and to sediment with IgM globulins on zone ultracentrifugation in sucrose density gradients. Sera from rats bearing progressively growing tumours and sera from rats, which had such tumours excised, were found to be less active than normal rat sera in the complement fixation test against isogeneic tumour and liver homogenates. It was considered that this suppression of naturally occurring anti-tissue antibodies may be a specific process related to the host immune response to the tumour.

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Small doses of cell-free Ehrlich ascites fluid given to mice 18hr after CCl⁴ effectively prevents resolution of the toxin-induced hepatorenal necrosis, thus duplicating the reported effects of washed Ehrlich tumour cells. The available data indicate that Ehrlich tumour fluid does not contain the agent directly responsible for resolution-inhibition, but rather contains an inducer which stimulates host tissues to form the ultimate inhibitor. Only in the presence of renal tubular necrosis is the inhibitor allowed to accumulate to levels which prevent resolution. The possibility that host-derived inhibitors include antiproteases is discussed.

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Mutagenic activity of quercetin and kaempferol on V79 Chinese hamster cells was investigated. Quercetin was proved to have mutagenicity not only by metabolic activation system using rat liver microsomes, but also by direct application method. Kaempferol was mutagenic by metabolic activation system, but its activity by direct method seemed very low. These data suggest that the tested flavonoids seem to be metabolized for exerting their mutagenic activity and V79 cells themselves have an enzymic activation system which metabolizes at a very slow rate but in a cumulative way.

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The behavior pattern of tumor cells in the development of hematogenous liver metastasis by Yoshida sarcoma and two strains of rat ascites hepatoma, AH7974F and AH13, in Donryu strain rats was investigated by electron microscopy. Tumor cells of every strain in liver sinusoids stretched their cytoplasmic protrusions toward the vascular wall and were actually in contact with the endothelial cells with their tips to form various types of junction-like structures. The most distinct one was characterized by parallel and straight arrangement of the opposing cell membranes across a gap of about 100Å. The endothelial discontinuity was easily produced by the projection of cytoplasmic processes and the compression of tumor cells. Through the endothelial defect, tumor cells of Yoshida sarcoma and AH13 migrated locomotively into the dilated spaces of Disse or directly toward the hepatic cells, while AH7974F cells were frequently covered by elongated endothelial cytoplasm. Destruction of the hepatic cells by AH7974F and AH13 cells was found to begin with the insertion of their cytoplasmic processes into the coated vesicles in the hepatic cells.
From these investigations, the particular interaction between tumor and normal cells seems to play an important role in the development of liver metastasis by these tumors.

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Electronic structures of naphthalene-, anthracene-, phenanthrene-, and benzo[a]pyrene-diol-epoxides were calculated by using CNDO/2 method together with the energy minimization method. By using these methods, the most stable geometry of molecules was automatically obtained. By comparing the total energy of phenanthrene-diol-epoxide with that of anthracene-diol-epoxide, the role of the bay region was studied in connection with the chemical reactivity. It is concluded that the bay region plays an important role when the diolepoxide reacts with the component of the biological system via S_N1 mechanism. Moreover, benzo[a]pyrene-diol-epoxide was shown to be very reactive because of the presence of the bay region as well as the large size of the molecule. When reaction proceeds via S_N2 mechanism, the bay region is found to have little effect on the chemical reactivity of the molecules.

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Four cell lines were established from the wild rodent, Millardia meltada; an untransformed cell line (MM-D), a non-producer (NP) cell line transformed with murine sarcoma virus (MM-GL4), and SV40-transformed cell lines (MM-8, MM-663). MM-D is epithelioid and contact-inhibited, whereas MM-CL4, MM-8, and MM-663 are fibroblastic and grow piling up.
No endogenous virus was induced in Millardia cell lines by a long-term culture with various inducers. Millardia cell DNA has no nucleotide sequence homology with cDNA of either murine leukemia virus or rat endogenous virus.

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Antigens expressed on urinary bladder cancer cells of transplantation and tissue culture lines, which originated in tumors induced by N-butyl-N-(4-hydroxybutyl) nitrosamine in individual ACI/N rats, were studied by several immunological methods. Tumor-specific transplantation antigen was determined by transplantability of cancer cells into syngeneic rats which had been immunized with the respective cancer cells by the ligation-and-release method. Two out of 6 bladder cancer lines showed high antigenicity but antigenicities of the other 4 lines were of low or undetectable level. Cross resistance was observed in the transplantation immunity among the 2 high antigenic lines but not in the other lines. Cell-mediated cytotoxicity was assayed by the microtestplate method. The lymphoid cells from ACI rats hyper-immunized with cancer cells of a high antigenic line showed a marked cytotoxicity against cancer cells of the immunizing line but not to cells of the other bladder cancer lines including another high antigenic line that induced a cross resistance in transplantation immunity. Tumor-associated cell-surface antigen was detected by membrane immunofluorescence test with serum which was raised in allogeneic Donryu rat by the high antigenic bladder cancer and absorbed with normal ACI rat tissues. The absorbed serum gave positive membrane fluorescence to cancer cells of the immunizing line and 2 other bladder cancer lines but not to cells of other 4 bladder lines and ACI tumors other than bladder cancer. The common antigen detected by the serological method was not reflected either in transplantation immunity or cell-mediated cytotoxicity of the immune lymphoid cells.

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Effect of BCG, conezyme Q₁₀, or their combination on ATPase activity in spleen lymphocytes of tumor-bearing rats was investigated in relation to changes in the content of individual coenzyme Q homologs in these cells. Contents of both coenzyme Q₉ and Q₁₀ in spleen lymphocytes significantly decreased in the late stage of Donryu rats bearing Sato lung carcinoma. Oligomycin-sensitive ATPase activity in spleen lymphocytes was also significantly depressed in this stage. The depressed, oligomycin-sensitive ATPase activity was significantly recovered by a 3-time intramuscular administration of coenzyme Q₁₀ emulsified with ethanol and saline, and the decreased contents of coenzymes Q₉ and Q₁₀ were slightly restored by this treatment. This enzyme activity was also significantly recovered by an intravenous administration of BCG, and was elevated more by the combined treatment with BCG and the emulsified coenzyme Q₁₀. These results suggest that the combined treatment with BCG and emulsified coenzyme Q₁₀ can contribute to the improvement of the depressed bioenergetics in lymphocytes of tumor-bearing animals, and that this combined effect of BCG and emulsified coenzyme Q₁₀ might be based on the combination of their individual activating effect on lymphocytes.

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The effect of purothionin-A obtained from wheat (Triticum vulgare, Manitoba No. 3) flour on various animal cells was examined. Purothionin-A at 6μg/ml was lethal to growing A-31 cells and cells transformed with polyoma virus, but it did not affect contact-inhibited A-31 cells even at 10μg/ml. Purothionin-A of these concentrations was found to kill only cells in the DNA-synthetic phase (S phase). It is of particular interest that it had little or no effect on cells in other stages.

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Adult A/J mice inoculated with 1×10⁶ syngeneic C1300 neuroblastoma cells had a palpable tumor after 1 week, and the tumor grew uniformly. The hypertonic KCl extract of the tumor induced blastogenic response of syngeneic spleen cells from tumor-bearing mice, and tumor antigens were considered to be solubilized by KCl from tumor cells. Although a higher blastogenic response to insoluble tumor antigens coupled to Sepharose 4B beads could have been expected as demonstrated in this mixed lymphocyte-tumor cell reaction (MLTR) assays, the blastogenic activity, which was approximately equal to that of soluble tumor antigens, was less than one-third of that in MLTR. The initial information of blastogenic response was found to be transmitted to the responder cells without the entrance of tumor antigens into the cells by the use of insoluble tumor antigens. Blastogenic responses to soluble tumor antigens and to irradiated tumor cells (MLTR) in spleen cells from tumor-bearing mice were serially assayed after tumor inoculation. The response to soluble tumor antigens reached a peak 2 weeks after inoculation but a progressive depression of the responses was observed after a marked tumor growth. Although the blastogenic activity of soluble tumor antigens was small, changes in consecutive responses to soluble tumor antigens in tumor-bearing mice were well correlated with those in MLTR. The blastogenic responses to soluble tumor antigens and MLTR were considered to be the manifestation of tumor-specific cell-mediated immunity. Furthermore, the serial blastogenic responses to concanavalin-A and lipopolysaccharide were also coincident with those of tumor-specific immunity.

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The effect of brain trauma on the formation of metastatic growth was examined by iv injection of 6 strains of rat ascites hepatoma. Three of the tumors (AH7974F, AH66F, and AH13) were in the single-cell state and three (AH272, AH7974, and AH601) contained cell aggregates. None of the tumors showed any tumor growth in the intact brain after injection into the tail vein. However, after traumatization of the brain tissue it was possible to observe tumor formation in the lesion, mainly by injection of the single-cell type tumors. The brain tissue was most susceptive to the tumor cells 10min and 7 days after trauma. On the other hand, after the injection into the carotid artery of traumatized animals, the tumor formation in the brain was found in both tumor groups.

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It was possible to produce gastric adenocarcinoma in five of 69, healthy, young albino mice of both sexes given N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in their drinking water at a concentration of 100μg/ml.
The tumoral lesions were most clearly defined in the group that received MNNG for the longest period of time, that is, 68 weeks. On the other hand, in the rest of the groups, which received MNNG for fewer weeks, there were lesions found in a total of nine animals which consisted in foci of typical and atypical hyperplasia, erosion of the mucosa, and, in one animal, an adenomatous polyp. Contrary to findings in humans, intestinal metaplasia preceding or accompanying the neoplasia was found to be an inconsistent alteration and a not very frequent one.

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The effect of uracil on the metabolism of 5-fluorouracil (5-FU) in vitro was studied. 5-FU was mainly phosphorylated in intact Yoshida sarcoma cells, whereas it was mainly degraded in liver slices. Uracil inhibited degradation of 5-FU much more than its phosphorylation; incubation of 2, 500μM of uracil with 2.5μM of 5-FU (molar ratio, 1, 000:1) inhibited the degradation of 5-FU by 70%, but did not affect its phosphorylation.
With homogenates of Yoshida sarcoma or liver, uracil inhibited degradation of 5-FU greatly, phosphorylation of 5-FU by α-D-ribose 1-phosphate (RiblP) and ATP to some extent, and phosphorylation by 5-phospho-α-D-ribosyl diphosphate (PPRibP) very little.
The activities of the enzymes involved in the metabolism of 5-FU in various tissues were also determined. Degradation of 5-FU was much faster in liver than in other tissues and was very slow in tumor tissue. Phosphorylation of 5-FU with RiblP and ATP was rapid in Yoshida sarcoma and bone marrow. Phosphoribosyltransferase activity was high in Yoshida sarcoma and thymus, but low in bone marrow.

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Effect of aluminium chloride on the binding of carcinogenic 4-hydroxyaminoquinoline 1-oxide (4-HAQO) with mouse lung DNA, RNA, and various homopolyribonucleotides was examined in vitro, in the presence of seryl-AMP. Mouse lung DNA, RNA, or homopolyribonucleotide [poly (A), poly (G), poly (I), poly (X), poly (C), or poly (U)] was pretreated with aluminium chloride in an ice bath and the binding with 4-HAQO was examined. Binding with DNA, RNA, poly (A), and poly (G) was markedly inhibited, and their binding rates were 46%, 56%, 53%, and 18% of that of the control, respectively. Binding with poly (C) and poly (U) was hardly different from that of the control. Consequently, effect of aluminium chloride in inhibiting the binding of 4-HAQO with mouse lung DNA and RNA is assumed to be due to the inhibition of its binding with guanine.
Effect of various metals (Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Fe³⁺) on the binding of 4-HAQO with mouse lung DNA was examined and it was found that aluminium chloride had the strongest inhibitory effect, followed by copper and zinc. Trivalent iron showed hardly any inhibition.

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The in vitro cytotoxicity of norditerpenoid dilactones isolated from Podocarpus plants was determined against cultured Yoshida sarcoma cells. The dilactones involved 15 natural lactones as well as their derivatives, which include appropriate modofications necessary to the estimation of the structure-activity relationship. The unsaturated system on the B/C ring portion, the dienolide or the epoxyenolide moiety, is essential for the activity, but the γ-lactone group on the A/B ring portion is not. Other oxygenated substituents on the skeletal carbons, such as hydroxyl, acyloxyl, or epoxide group, also show some significant effect.

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Transplantation of 9 kinds of bracken-induced ileal adenocarcinomas subcutaneously in ACI rats established two transplantable strains of adenocarcinoma (73-357, 77-238). Ascitic conversion succeeded in the strain 73-357. Biological and morphological, particularly electron microscopic, characteristics of these strains are reported.

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Transplacental induction of lung tumor by 1-ethyl-1-nitrosourea (ENU) was studied in pregnant ddY mice which were given a single intraperitoneal injection of 58.5mg/kg of ENU in water between day 13 and 19 of gestation. Within 4∼6 weeks after birth, pulmonary tumor nodules were found in all offsprings exposed to ENU, and they were histopathologically adenoma. Number of tumor nodules could be counted under the stereomicroscope from approximately day 40 after birth. The size of tumor increased with the lapse of time but the number of tumor nodules did not increase markedly. Weekly injections of urethan or ENU into mice pretreated with ENU in their fetal age enhanced the number of pulmonary adenoma. The development of other tumor was not seen except a few cases of lymphoma. Tumor development in the lung by injection of ENU in ddY mice during gestation is reproducible, relatively simple, and rapid. Therefore, it is considered that this may be a useful method for screening of antitumor agent.

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Transplantation of tumor cells subcutaneously in the ear of a rat induced marked metastasis formation in the cervical lymph nodes. When the cell suspension was inoculated rapidly, metastasis occurred very early, while tumor grew first at the site of the injection and then metastasis occurred late when that was done rather slowly.

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Pretreatment of tumor-bearing rats with OK-432 resulted in an increased uptake of ⁵⁷Colabeled bleomycin by the tumor (47%). This finding may explain one of the reasons for the synergism between OK-432 and anticancer chemotherapeutics.

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The antiestrogen, tamoxifen, caused immediate arrest of growth and subsequent regression of transplantable pregnancy-dependent mouse mammary tumors (TPDMT-4) when injected 3 times weekly at a daily dose of 1mg in pituitary isograft-bearing mice.

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Glycosaminoglycans of small cell carcinoma tissue were characterized and their elevated level was demonstrated. Small cell carcinoma contained hyaluronic acid three times more than sulfated glycosaminolycans, while the proportion was reversed completely in adenocarcinoma and squamous cell carcinoma.

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Degraded carrageenan first induces colitis, secondarily squamous metaplasia, and finally various types of tumor in rats. The squamous metaplasia of colorectal mucosa progresses irreversibly after the cessation of degraded carrageenan administration. The irreversible squamous metaplasia is possibly a precursor of squamous cell carcinoma

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Hepatocarcinogenicity of benzo[a]pyrene was studied by intraperitoneal application of this compound to rats 24 hr after partial hepatectomy. Numerous enzyme-altered islands, similar to putative precancerous lesions induced by known hepatocarcinogens, developed by the 12th week.

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