Analbuminemic rats were found to be highly susceptible to induction of gastric tumors by N-methyl-N'-nitro-N-nitrosoguanidine (67-83μg/ml) given to the rats in drinking water for 32 weeks. The rats were sacrificed at experimental week 44. Gastric tumors were found in 12 of 17 analbuminemic rats (70%) and in 8 of 21 normal rats (38%). Intestinal tumors developed in 7 of 17 (41%) analbuminemic rats and in 9 of 21 (42%) normal rats.

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Des-O-methylolivoretin C, a demethylated form of olivoretin C, is a naturally occurring compound in Streptomyces mediocidicus and Streptoverticillium olivoreticuli. Des-O-methyl-olivoretin C is a regioisomer of teleocidin B, which has the same activity as teleocidin. The tumor-promoting activity of des-O-methylolivoretin C was studied in a two-stage carcinogenesis experiment on mouse skin in comparison with that of teleocidin. Treatments with 7, 12-dimethylbenz-[a]anthracene (DMBA) plus des-O-methyl-olivoretin C and DMBA plus teleocidin induced tumors in 63.3% and 84.6 of the mice, respectively, in week 30. The difference in the tumor-promoting activities of des-O-methylolivoretin C and teleocidin is presumably related to the regioisomeric difference in the cyclohexene ring.

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Human placental form of glutathione S-transferase (GST-π) was detected in human colonic carcinomas and adenomas by peroxidase anti-peroxidase method using antibody raised against GST-π. Of 60 carcinomas, including differentiated adenocarcinomas and undifferentiated carcinomas, 88% were positive for GST-π staining, and 47% of 23 adenomas were also positive. In the normal colonic mucosa, GST-π was not detectable or was only weakly stained in the basal parts of the absorptive cells or in the cytoplasm of the cells containing little mucin. These results indicate that GST-π is a possible new marker for immunohistochemical detection of human colonic carcinoma and some adenomas.

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Four antioxidant species, butylated hydroxyanisole (BHA), butylated hydroxy-toluene (BHT), ethoxyquin and α-tocopherol, and three other compounds, 4, 4'-diaminodiphenylmethane (DDPM), acetaminophen and glutathione, were tested for inhibitory effect on hepatocarcinogenesis in male F344 rats. Rats were initially given a single ip injection of diethylnitrosamine (200mg/kg body weight) and fed basal diet containing 0.02% 2-acetylaminofluorene from week 2 to week 8. Animals were subjected to partial hepatectomy at the end of week 3. From week 12 to week 36, they were given basal diet containing 2% BHA, 1% BHT, 0.8% ethoxyquin, 1% α-tocopherol, 0.1% DDPM, 1% acetaminophen, or 1% glutathione, then killed at week 40, 4 weeks after cessation of treatment with the test chemicals. The incidence of hepatocellular carcinoma (HCC) was significantly decreased in the groups given ethoxyquin or DDPM. Quantitative analysis of the number and area of HCC per unit liver area revealed a significant decrease in the area of HCC in the groups given ethoxyquin, DDPM or acetaminophen. The results suggest that ethoxyquin, DDPM and acetaminophen exerted an inhibitory effect on the development of HCC, while BHA, BHT, α-tocopherol and glutathione had no significant effect.

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Three groups of male Fischer rats were given single doses of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) at 160mg (group 1), 80mg (group 2) and 40mg (group 3)/kg body weight by gastric intubation. A fourth group was given drinking water containing 100μg/ml of MNNG for 2 weeks, and a fifth group served as a control. Rats were killed in weeks 5, 8 and 12. Serial sections of the pyloric mucosa were examined by paradoxical concanavalin A (Con A) staining and pepsinogen isozyme 1 (Pg 1) immunostaining. All pyloric glands contained class III mucin as detected by paradoxical Con A staining. Most pyloric glands had a high Pg 1 content, but a few stained only weakly if at all. The percentage and number (No./500 normal-looking pyloric glands) of pyloric glands with a low Pg 1 content were 50.0 and 0.2±0.4 (week 5), 87.5 and 0.5±0.4 (week 8) and 100.0 and 1.2±1.0 (week 12) in group 1, 50.0 and 0.2±0.3 (week 8) and 87.5 and 0.5±0.4 (week 12) in group 2, and 30.0 and 0.2±0.4 (week 12) in group 4. No pyloric glands with a low Pg 1 content were found in groups 3 and 5. Thus the results showed significant dose-dependent induction (P<0.05-0.01) of altered pyloric glands demonstrating reduced Pg 1 content and their earlier appearance in groups given higher doses of MNNG. The results suggest that the appearance of pyloric glands with a low Pg 1 content may be a preneoplastic change in gastric carcinogenesis.

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Large amounts of murine mammary tumor virus (MMTV) were expressed in milk from a low mammary tumor mouse strain called II-TES, established by crossbreeding DBA/2 mouse strain with two strains of Japanese pet mouse origin. The reciprocal hybrids of the II-TES strain and OZ-F strain, another low mammary tumor strain of Japanese pet mouse origin, developed early-appearing mammary tumors at a high rate, and large quantities of MMTV were expressed in the milk. These findings suggest that different regulatory genes control MMTV expression and mammary tumorigenesis.

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We investigated the prevalence of antibodies to human T-cell leukemia virus type I (HTLV-I) associated antigens in various patients and healthy individuals in the Republic of Korea. Seventeen out of 6, 255 individuals (0.27%) were seropositive. The positive rate in males was 0.21% and that in females was 0.36%, the sex difference being similar to that in endemic areas in Japan. HTLV-I carriers were found in Seoul and neighboring areas, but not in Busan city or Jeju Island, which are adjacent to Kyushu, Japan. The prevalence of sera with definite anti HTLV-I antibodies seems to be very low in the Republic of Korea.

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In order to clarify the mechanism of transformation, the effect of cell generation number on the time of appearance of transformed cells was examined in γ-ray-irradiated BALB/3T3 A31-1-1 cells. The results showed that an increased number of cell generations (produced by seeding of cells at lower cell densities as well as under dispersed conditions) was important for increasing the rate of transformation. By a procedure in which irradiated cells in dishes were dispersed by trypsinization and recultured in the original dishes after cultivation for a certain number of days, we expected to establish the so-called “expression period.” The rationale was that the number of transformed foci would increase after the appearance of a transformed cell due to its expansion. The expression period was shown to be 1.5 weeks on average. The time of appearance of transformed cells, however, varied from as early as about 1 week to 2.5 weeks. When cells were seeded at higher or lower cell densities and examined by the technique of dispersion and reculture, the expression periods were almost the same. Thus, it is probable that transformed cells can appear before or after the confluent state is reached.

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We investigated the effects of polyprenoic acid, E5166, on the production and secretion of α-fetoprotein (AFP) and on cell kinetics in a human hepatoma cell line (HuH-7). The cellular AFP content, measured flow cytometrically for cells stained by an indirect immunofluorescence method, was decreased by treatment with E5166. AFP in the culture medium decreased exponentially during exposure of cells to the drug. These changes were dose-dependent. The growth of HuH-7 cells in vitro was clearly suppressed in the presence of E5166. The inhibition of growth depended on the concentration of the agent. The fraction of S phase cells decreased relatively in the cells treated with a high concentration of the drug, whereas it increased in the cells treated with lower doses.

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Out of seven human carcinoma cell lines (M7609, CCK-81, FCC-1, RPMI#4788, QGP-1, HLC-1, and KNS-62), 4 cell lines were found to produce immunoreactive calcitonin (ICT), a potential tumor marker for various malignancies. During a 7-day culture, 1.4×10⁵ QGP-1, RPMI#4788, HLC-1, and KNS-62 cells secreted 7, 000pg, 500pg, 400pg, and 400pg of ICT in the medium, respectively. The production of ICT by QGP-1 cells was increased by addition of pentagastrin or calcium gluconate. Three different components of ICT (peak I, molecular weight>40, 000; peak II, 14, 000-18, 000; peak III, 3, 400) were detected by gel filtration of the QGP-1 spent medium. In a competitive inhibitiontype radioimmunoassay of serial dilutions of each ICT component, peak III component showed very similar immunoreactivity to synthetic calcitonin. However, the other two components gave clearly different immunoreactivities from the peak III component and showed very similar immunoreactivities to each other. All the cell lines were further screened for synthesis of 7 other tumor markers, carcinoembryonic antigen, nonspecific cross-reacting antigen, CA19-9, tissue polypeptide antigen, α-fetoprotein, β₂-microglobulin and ferritin. Every cell line produced 2 to 6 markers concomitantly, and various combinations of positive markers were found among the cell lines.

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DNA ploidy patterns of minute carcinomas in the stomach were determined by cytofluorometric measurement, using paraffin sections which had been prepared for histological examination. The examples studied were 19 minute carcinomas less than 5mm in diameter, of which 12 were adenocarcinomas, and 7 were signet ring cell carcinomas. By measuring the fluorescence intensity of more than 30 mitotic nuclei, the DNA ploidy pattern of each tumor was determined. The control diploid DNA content was obtained by measuring the fluorescence intensity of non-cancerous mitoses in the gastric mucosa. In the present study, heteroploidy was seen in 5 carcinomas; 4 adenocarcinomas and one signet ring cell carcinoma. The remaining 14 carcinomas were composed of a diploid stem cell line. In 3 adenocarcinomas, polyploid cells were seen. The occurrence of heteroploidy in the minute cancers was similar to that found in advanced cancers, whereas polyploid cells appeared to occur less frequently in the minute cancers than in the advanced cancers.

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A total of 137 consecutive gastrectomy specimens from Japanese patients having either chronic peptic ulcer, focal (elevated) dysplasia or intramucosal carcinoma were scrutinized under high-power examination (×1000) for the presence of ciliated cells. In 48 specimens (35.0%) ciliated cells were found in non-neoplastic dilated pyloric glands. The highest percentage was found in cases with focal (elevated) dysplasia (42.6%) or intramucosal carcinomas of intestinal type (41.6%) and the lowest in cases with intramucosal carcinoma of the diffuse type (15.4%) or chronic peptic ulcer (16.0%). Ciliated cells in the gastric mucosa seem therefore to be a common phenomenon in Japanese subjects and appear to be a new indication that the gastric mucosa of Japanese patients may differ from the gastric mucosa of Europeans.

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A long-term cohort study of 639 males in a farming area and 677 males in a fishing area in Kyushu, Japan, has been conducted to evaluate risk factors for ischemic heart disease. The present investigation utilized this long-term cohort study to assess the role of drinking and cigarette smoking habits in the causation of liver cancer. The O/E ratio (ratio of the observed to expected number of deaths) of liver cancer was 7.5 (P<0.001) among shochu drinkers in the fishing area. Further, a clear dose-response relationship of O/E ratio was noted: 5.7 (P<0.001), 7.5 (P<0.001) and 20.0 (P<0.001) for drinkers of <1, 1-2, and 2 or more units of shochu (a distilled alcoholic beverage made in Japan; about 25% alcohol). Although no excess risk was found among shochu drinkers in the farming area, observed and expected numbers were too small to make valid judgements. Among sake drinkers, the observed and expected numbers were very similar in both areas. Cigarette smokers in the fishing area appeared to have a high risk for liver cancer, the O/E ratio being 4.8 (P<0.001). However, there was no clear dose-response relationship and O/E ratios among cigarette smokers according to their drinking habits indicated no excess risk among nondrinkers. A multiple logistic regression analysis showed an insignificant effect of cigarette smoking on the development of liver cancer after adjustment for shochu drinking. These findings suggest a significant involvement of shochu drinking in the etiology of liver cancer, at least in this fishing area.

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To clarify risk factors of multiple primary cancers in breast cancer patients, a casecontrol analysis based on data from medical records was conducted at the Aichi Cancer Center Hospital. For each of a total of 115 multiple primary cancer patients affected by one or two other primary cancers after or concurrently with breast cancer, two patients with unilateral breast cancer were selected as controls by matching age, time of the operation for breast cancer, and survival period. Multiple primary cancer patients were then divided into two groups, 61 cases of bilateral breast cancer and 56 cases of other multiple primary cancers. Conditional multiple logistic regression analysis indicated that relatively heavy smoking (more than 10 cigarettes per day) decreased the risk of multiple primary cancers taken overall (relative risk (RR)=0.23); overweight status elevated the risk of bilateral breast cancer (RR=3.01); and greater than average height (RR=2.20), history of gallstone or cholecystitis (RR=6.29), and late first birth or nulliparous status (RR=6.85) elevated the risk of other multiple primary cancers. The effects of weight and height were predominant in the postmenopausal women. As to family history, we could not obtain clear results, though history of cancer among siblings tended to increase the risk of multiple primary cancers (P< 0.10) and family history of breast cancer was more frequent in patients with bilateral breast cancer (not significant).

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Intraperitoneal inoculation of L1210 murine leukemia cell vaccine increased I-A^d antigen-positive and -negative macrophages in the peritoneal cavity of histocompatible mice. Mitomycin C, a poor producer of I-A^d antigen-positive macrophages, selectively augmented the production of I-A^d antigen-positive macrophages in L1210 vaccine-primed mice, since it did not augment the production of non-macrophage cells. Since our previous study showed that the priming of mice with L1210 vaccine and mitomycin C induced augmented antitumor response, we tested the feasibility of the association of mitomycin C-augmented I-A^d antigen-positive macrophages with the augmented antitumor response. Prostaglandin E₂ suppressed the antitumor response in L1210 vaccine- and mitomycin C-primed mice and, consistent with this, it inhibited the production of I-A^d antigen-positive macrophages, although it inhibited the production of non-macrophage cells as well. This hypothesis was further tested by the use of silica. When L1210 vaccine- and mitomycin C-primed mice were further given silica on the day of and one day after live L1210 inoculation, their antitumor response was strongly suppressed, while a kinetic analysis of the cellularity of peritoneal cells showed that administration of silica resulted in a decrease of I-A^d antigen-positive macrophages, but not I-A^d antigen-negative macrophages or non-macrophage cells in these mice. These results strongly suggest, though they do not prove, the association of mitomycin C-augmented production of I-A^d antigen-positive macrophages with the antitumor response in L1210 vaccine- and mitomycin C-primed mice.

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The antitumor effects of two-drug simultaneous or sequential use of cisplatin, vindesine or etoposide were examined in human pulmonary adenocarcinoma cell lines by human tumor clonogenic assay. Different tumor cell lines (PC-9, PC-13 and PC-14) that originated from the same histological cell type responded quite variably to simultaneous and/or sequential therapy. The antitumor effects of various sequential combinations of cisplatin, vindesine and etoposide depended strongly on the nature of the individual tumor cell line tested.

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