Twenty selected compounds were tested for antitumor activity against DMBA-induced skin tumors in mice.
Cytoxan and 6-mercaptopurine were the most effective, producing complete regression of papillomas in 57%, in contrast to 28% spontaneous regression in the controls. Cytoxan also caused complete destruction of squamous cell carcinomas in 25% while none occurred in the controls.
Repeated subcutaneous injections of testosterone propionate definitely increased the frequency of regressions of DMBA-induced papillomas in female mice (56%) while the same tumors were resistant (9%) to estradiol, a female sex hormone. Testosterone propionate caused complete destruction of squamous cell carcinoma in 40% of the cases, while estradiol was ineffective against squamous cell carcinoma.

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In vitro cloning from the cultured tumor cells of Friend viral leukemia origin was carried out in order to isolate the non-virus producing cells, which were possibly contained in the cell population. Cloning efficiency was 56%. All of the 119 clonal sublines tested did produce the virus, though with a variety of infectivity. Several low-titer clones were obtained and their growth either in vitro or in vivo was similar to that of the high-titer ones. Clones were resistant to challenge infection with the Friend virus of high infectivity. Further analysis may be required for solution of the problem of whether the persistent infection of the active virus in leukemia cells is indispensable or not for maintenance of neoplastic growth of the cells.

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One hundred and five autopsy cases of gastric carcinoma were studied macroscopically and microscopically, of which 50 showed metastasis in the lung. Forty-four of these 50 cases demonstrated lymphatic involvement. In these cases, especially in 35 cases which had focal or incipient lymphangiosis, the route by which the cancer cells reached the pulmonary lymphatics was studied. Hematogenous route was suspected in 11 cases, and hematogenous route was highly suspected though other routes could not be denied in 12 cases. The route via diaphragm was considered in 2 cases and the route via diaphragm was highly suspected though other routes could not be denied in 2 cases. There was no typical case in which lymphangiosis was considered to have progressed by way of the retrograde lymphatic route.
From these observations it would appear that many, at least one-half, of the cases with lymphangiosis carcinomatosa resulted from blood-borne tumor cell emboli, which lodged in the smaller pulmonary arteries and subsequently spread through the vessel walls into the perivascular lymphatics.

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An attempt was made to utilize organ culture for the in vitro screening of carcinostatic agents. The tissues, cut into pieces approximately 1.5mm in diameter, were exposed to the agents for 42-45 hours in organ culture and then incubated with ³H-thymidine at a concentration of 5-10μCi/ml, for 4 hours.
Viability of the tissues was evaluated by the incorporation of ³H-thymidine into DNA of the cultured tissue. DNA was extracted by the Schmidt-Thannhauser and Schneider methods.
Effect of several carcinostatic agents on normal and malignant tissues was examined. The results thus far obtained indicate that the susceptibility of tumors to carcinostatic agents differs by tumor type. The in vitro method appears useful for the screening of carcinostatic agents.

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A procedure had been devised by which in vivo liver catalase-depressing substance is extractable as its aqueous solution from particles of the cells of normal muscle and Rhodamine sarcoma of rats.3) Some nature of the solubilized substance was studied.
1) By molecular sieve fractionation of the extract, either on Sephadex G-75 column or on Sephadex G-200 column, the in vivo catalase-depressing activity of the extract was separated into two fractions, excluded and diffused, indicating that the extract contained at least two kinds of active substance different in molecular size.
2) When the extract was dialyzed and then adjusted to pH 4.0, precipitation occurred. Both precipitate and supernatant showed the activity. By the isoelectric fractionation with Ampholine-carrier Ampholyte, the supernantant was divided into fractions of different isoelectric points of 3.39-3.43, 3.44-3.90, 4.05-4.60, 4.82-5.31, 5.45-6.75, 7.19-8.76, and 8.82-9.48. All the fractions but that of pI 7.19-8.76 showed the activity, indicating that the supernatant contained various active substances different in isoelectric point.
From these findings, it is concluded that the in vivo catalase-depressing substance varies in chemical composition and/or in mode of existence.

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The presence of two types of aldolase isozyme, aldolase-A (muscle type) and aldolase-B (liver type), was demonstrated in various human tissues as in other mammals. The skeletal muscle contained primarily aldolase-A, while the liver contained primarily aldolase-B. The other tissues, including red cells, possessed mixtures of aldolase-A and -B in proportions characteristic to each tissue.
Cancerous tissue of liver was found to produce aldolase-A, which was not usually found in the liver, as well as aldolase-B. Gastric cancer contained higher concentration of aldolase-A than normal gastric mucosa. This was also the case in the cancer of liver and colon, irrespective of absolute activity of FDP-aldolase in the tissues.

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Crude polysaccharide fractions were prepared by adding ethanol to the aqueous extracts of lichens and their inhibiting effect was tested on subcutaneously implanted sarcoma-180. All the samples tested were found to be highly effective. Seven of the ten samples showed inhibition ratios of above 90%, two between 80 and 90%, and one between 70 and 80%. Complete regression of the tumor was observed in many cases.
From Gyrophora esculenta Miyoshi, the active principle, a partially acylated β-1, 6-glucan, was isolated in a pure state and its antitumor effect was tested. The inhibition ratio was 99.1% and complete regression occurred in 8 out of 10 mice. Lichenin and isolichenin were roughly isolated from Cetraria islandica (L.) Ach. var. orientalis Asahina and they showed inhibition ratios of 100% and 99.6%, respectively.
This effect was considered to be host-mediated and not due to the cytocidal action. As a conclusion, lichen was suggested to be a promising source of the polysaccharides with this type of antitumor effect.

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Induction of squamous neoplasms was demonstrated in mice by the combination of the prolonged inhalation of vapor of aluminium compound and single subcutaneous injection of 4-nitroquinoline 1-oxide. Incidence of typical lung adenoma was lower than the single application of 4-nitroquinoline 1-oxide.

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Cell proliferation was induced by the addition of N-nitrosodimethylamine in a primary culture of liver cells from newborn Buffalo rat. This increase can be maintained in subsequent cell pas ages, but no growth was obtained in the non-treated control group for over 65 days of culture.

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Two cell lines were established in continuous cultivation from the enlarged spleen of each of two BALB/c mice with Rauscher leukemia. The cells are composed of primitive cells resembling immature reticulum cells and erythroblasts in various stages of maturity. The supernatant culture fluids are leukemogenic upon inoculation into suckling mice.

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Antitumor activity and some chemical properties of crude polysaccharide fractions prepared from four edible Basidiomycetes were examined. Preparations from boiling water extraction of Flammlina verutipes and from 2N NaOH extraction of Photiota nameko were most effective. Chemical studies showed that these were mainly glucose polymer which was considered to consist partially of β-(1→3)-linked D-glucose residues.

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