Envelope gene product of human T-cell leukemia virus was identified as a glycoprotein with an apparent molecular weight of 62, 000 daltons, by using rabbit antiserum against a synthetic decapeptide whose structure had been predicted from the nucleotide sequence. Sera from patients with adult T-cell leukemia also reacted with this glycoprotein.

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Cellular DNA transfection to mouse NIH3T3 cells revealed transforming activity of human malignant melanoma DNA. The corresponding human sequence was cloned from the transformed mouse cells. By hybridization to viral oncogenes, the transforming gene in human melanoma was identified as a homologue of viral Ha-ras gene.

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Southern blot analyses revealed amplification and rearrangement of c-Ha-ras-1 sequence in the DNA of one biopsied specimen of bladder carcinoma. DNA from normal cells, leukocytes, of the same patient showed no such changes. Therefore, the amplification and rearrangement described here seem to be associated with the development of the cancer.

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Human fetal thymuses were investigated in a search for retroviruses. By electron microscopy, retrovirus-like particles were detected in the thymus cells only when they were cocultured with mitomycin C-treated human B-cells. Reverse transcriptase activity in the culture medium was found at a density of 1.15-1.17g/cm³ in sucrose density gradients.

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The effect of butylated hydroxytoluene (BHT) on γ-glutamyl transpeptidase (GGT) activity in F344 rat liver was investigated. GGT activity was significantly higher after the 1st week of BHT feeding than in control rats, and the high activity was maintained until BHT feeding was stopped. Four weeks after the cessation of an 8-week course of BHT feeding, there was no difference in liver GGT activity between control rats and BHT-treated rats. Histochemical analysis showed that GGT-positive hepatocytes appeared in periportal areas of the liver lobules in BHT-treated rats.

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Thiram was added at levels of 0.1 and 0.05% to the diet of F-344 rats for 2 years. The results indicated that thiram significantly reduced the incidence of spontaneous leukemia, and also tended to reduce the incidences of pituitary and thyroid tumors.

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A specific and sensitive radioimmunoassay for human pancreatic growth hormone-releasing factor (hpGRF) was developed. Using this radioimmunoassay, it was found that immunoreactive hpGRF (which is present in hypothalamic tissues) of at least two different molecular sizes is often produced by small cell carcinoma of the lung.

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B3 murine IgG₁ monoclonal antibody against BC47 rat bladder cancer detected an antigen distributed on the cell surface of neoplastic cells and proliferating normal tissue cells. The percentage of B3 antigen-positive cells in lymphocytes was increased by mitogen stimulation. The molecular weight of the antigen was 130, 000 or 140, 000 daltons.

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N-2-Fluorenylacetamide (FAA)-induced hepatocarcinogenesis in three colonies of Wistar-strain rats was studied. Two specific inbred colonies of rats derived from a Wistar strain, normotensive rats of Wistar Kyoto colony (WKY) and spontaneously hypertensive rats separated from WKY(SHR), showed higher inductions of preneoplastic altered foci of basophilic cell type and hepatocellular carcinomas as compared to common closed colony rats of the same strain (CWR). After 7 weeks of 0.02% FAA-containing diet, preneoplastic foci in WKY were found 4.8 times more frequently and in SHR 2.5 times more frequently than in CWR. Most of the foci found in WKY (92.5% of the total number of foci) and in SHR (87.1%) were of basophilic cell type, whereas most of the foci in CWR (71.3%) were acidophilic. After 7 months of the diet, multiple hepatocellular carcinomas were found in most rats in WKY (87.5% of the total number of rats, 2.6/rat) and SHR (81.8%, 2.5/rat) as compared to CWR (14.3%, 0.14/rat). These data demonstrate that rats in specific inbred colonies possess even higher susceptibility to FAA than CWR, and the susceptibility is closely related to the higher incidence of basophilic foci.

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4'-Epiadriamycin and 4'-O-tetrahydropyranyladriamycin (THP-adriamycin), derivatives of adriamycin, strongly inhibited in vitro reactions of DNA polymerases α and β from calf thymus by competing with activated DNA (template-primer). Preincubation of DNA polymerases with 4'-epiadriamycin or THP-adriamycin strongly inhibited the DNA polymerase, but the inhibition was reversed by adding excess amounts of template-primer. These results indicate that 4'-epiadriamycin and THP-adriamycin inhibit the in vitro reactions of DNA polymerases by direct interaction of the drugs with the enzymes as well as by impairing the template activity through intercalation into DNA, in agreement with results obtained for other anthracycline antitumor agents, daunomycin and adriamycin. The activity of DNA polymerase α may be more sensitive to both 4'-epiadriamycin (Ki, 9μM) and THP-adriamycin (Ki, 5.5μM) than that of DNA polymerase β (Ki30μM for 4'-epiadriamycin and 22μM for THP-adriamycin). DNA polymerase I from Escherichia coli was inhibited by these drugs in the same manner as DNA polymerase α. On the other hand, the inhibition of RNA polymerase from E. coli was more marked when the drug was preincubated with template DNA than with the enzyme.

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The nature of phorbol ester receptors in intact Friend erythroid leukemia cells (FLC) was examined by utilizing ³H-phorbol dibutyrate (³H-PDBu). FLC were shown to possess one class of specific and saturable ³H-PDBu receptors with high affinity, that is, with a Kd of 14.1±4.2nM and 1.1×10⁵±0.22 binding sites/cell, as revealed by Scatchard analysis. The specific phorbol ester binding activity of FLC was shown to be phospholipid-dependent, since it was sensitive to treatment of the cells with phospholipase A₂ or C and also was inhibited competitively by phospholipid-interacting agents such as antipsychotic or anticalmodulin drugs. The relative potency of the drugs for the inhibition of PDBu binding to FLC was parallel to that for the inhibition of protein kinase C.

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Conditioned medium obtained from mouse mammary fibroblasts markedly stimulated both DNA synthesis and cell proliferation in primary monolayer cultures of mouse mammary tumor cells. Growth of normal mammary epithelial cells from virgin female mice was likewise stimulated by the conditioned medium. The growth-stimulating activity was absent in conditioned media from 3T3 cells, 3T6 cells, mouse embryonic and lung fibroblasts, mammary tumor cells and normal mammary epithelial cells. Stimulation of DNA synthesis in mammary tumor cells was also observed with epidermal growth factor (EGF), although the effect was less than that observed with the conditioned medium. Receptor studies using ¹²⁵I-labeled EGF further showed that the specific binding of EGF to mammary tumor cells was not inhibited by the conditioned medium. The molecular weight of the growth-stimulating activity in mammary fibroblast-conditioned medium was estimated to be approximately 100, 000 daltons by Sephadex G-200 column chromatography. These observations suggest that mammary fibroblasts, which constitute the stroma of the mammary gland, produce a mammary epithelial cell growth factor(s) distinct from EGF.

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Lethal effects of mitomycin C (MMC), 4-nitroquinoline 1-oxide (4NQO) and ultraviolet light (UV) on fibroblast cell lines derived from a colon cancer-prone substrain of Wistar-Furth rats (WF/OSAKA rats) were measured in terms of the cellular colony-forming ability, and compared with the sensitivity to these agents of human fibroblasts from patients with adenomatosis coli and rectum (ACR). All 6 fibroblast strains from the cancer-prone WF/OSAKA rats were significantly more sensitive (though to various extents) to MMC as well as 4NQO than normal rat fibroblasts derived from the parental WF Hiroshima rats. These WF/OSAKA cell strains were slightly more sensitive to UV than normal rat cell strains. Similarly, 5 out of 6 fibroblast strains derived from ACR patients were hypersensitive to both MMC and 4NQO. Further, the WF/OSAKA cell strains were more susceptible to morphological transformation induced by Kirsten murine sarcoma virus than normal rat strains. The observed higher sensitivity to chemical agents and to viral transformation suggests a close similarity in cellular terms between the colon cancer-prone WF/OSAKA rats and human individuals affected with ACR.

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The effects of triiodothyronine (T₃), hydrocortisone, and insulin on X-ray-induced transformation of BALB/3T3 A31-1-1 cloned cells were examined. Under the experimental conditions employed, the addition of 10^-7M T₃ or hydrocortisone to the serum-containing medium had little effect on the transformation. In contrast, the addition of insulin dramatically enhanced the transformation. The effect of insulin was concentration-dependent up to 10μg/ml and was consistently observed with X-rays at various doses.

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An α-fetoprotein (AFP)-producing human gastric carcinoma was transplanted into BALB/c-nu/nu nude mice. The original tumor tissue had been obtained by gastrectomy from a 72-year-old patient with gastric carcinoma. The tumor had been transplanted serially (20 passages) in nude mice. The transplantability was 100%. The doubling time of the tumor ranged from 5.6 days to 11.2 days. AFP appeared in the serum of nude mice 3 to 4 weeks after subcutaneous (sc) transplantation and 6 weeks after intraperitoneal (ip) transplantation of the tumor cell suspension prepared from sc transplanted tumors. A positive correlation was observed between serum AFP level and tumor size. Serum AFP level of mice given ip transplantation increased as a function of time after transplantation. AFP was stained positively by an immunochemical technique in the original and transplanted tumors and was located in the cytoplasms of the tumor cells. The histology of the original tumor was retained. The malignant potential of these transplanted tumor cells was expressed as carcinomatous peritonitis and liver and/or lung metastases.

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A novel cultured cell line, P32/Ishida, was established from a Japanese 8-year-old boy with abdominal Burkitt's lymphoma. The P32/Ishida cells were proved to have immature B-cell phenotypes on the basis of immunological surface marker analysis: surface immunoglobulins (γ, μ, κ), Ia-like antigen, B1 antigen, and common acute lymphoblastic leukemia antigen were positive. A small amount of IgM, but no IgG, could be detected in both cell extract and culture supernate of P32/Ishida cells. Cytogenetic studies revealed that the P32/Ishida cells consisted of cells having three derivative karyotypes characterized by common marker chromosomes, dup(1), and 14q+ due to a new variant chromosomal translocation (2;14), which has not been identified in usual Burkitt's cell lines. Epstein-Barr virus nuclear antigen and terminal deoxynucleotidyl transferase activity were confirmed to be negative.

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The characteristics of natural killer (NK) activity of human peripheral blood lymphocytes treated with human leukocyte interferon (HuIFN-α) were compared with those of the untreated original NK activity. HuIFN-α, at a concentration of 50IU/ml or more, augmented the NK activity against BALL-1, Daudi, and Namalwa target cells. On the other hand, the augmentation was less evident for the activity against Raji and Molt-4 cells. Original NK activity was detected mainly in the fraction that passed through a nylon wool column. Nylon-retained cells, however, could be activated by the addition of HuIFN-α to express activity against BALL-1. The activity of the nylon-passed fraction was augmented by HuIFN-α as well as that of unfractionated cells. NK cells could be activated by HuIFN-α under calcium-free conditions that allow NK cells to bind but not to lyse the target cells; augmented cytotoxicity was observed when calcium was added 2hr later. This suggests that the augmentation of NK activity by HuIFN-α may have resulted from an increase in the number of NK cells.

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Changes in natural killer (NK) cell, antibody-dependent cell-mediated cytotoxicity (ADCC) and interferon activities after administration of Nocardia rubra cell wall skeleton (N-CWS) to a group of subjects with high risk of lung cancer (retired workers of the Okunojima poison gas factory) were studied. No difference in NK cell activity against K-562 derived from chronic myelogeneous leukemia was observed among normal controls, non N-CWS-injected workers and N-CWS-injected workers. None of the normals or N-CWS-injected retired workers showed low NK cell activity (less than 10% cytotoxicity), but among the non N-CWS-injected workers 6.3% showed reduced activity. Following injection of N-CWS, NK cell activity against K-562 and T-24 derived from bladder cancer was significantly elevated by the second week and then gradually reverted to the preinjection level. When a second injection was administered at the twelfth week, a similar elevation was noted. Further, a significant increase was noted in ADCC activity two weeks after N-CWS injection. There was a significant elevation of interferon at the second week after N-CWS injection. It was considered that N-CWS affects the NK cell activity enhancement by serum interferon.

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The effects of cis-dichlorodiammineplatinum (CDDP) on the cell kinetics of human neuroblastoma both in vitro and in vivo were analyzed by computer-aided flow cytometry. In the in vitro system, CDDP at the concentration of 1.0μg/ml of medium blocked early S phase and synchronized proliferating cells into the S phase within 24hr. By 72hr, cells in G₂+M phase reached the maximum level. CDDP at concentrations either lower or higher than 1.0μg/ml showed no synchronization effect. In the in vivo system, human neuroblastoma grown in nude mice had a larger proportion of cells in G₀-G₁ phase than did in vitro cells of the same origin, explaining the refractory nature of the tumors to therapy. CDDP, when given as a single dose of 10mg/kg of mouse weight showed a maximum synchronization of cells in the S phase by 48hr, and caused an accumulation of cells in G₂+M phase by 72hr. This accumulation of cells in G₂+M phase was thought to represent the overflow of cells from the S phase into G₂+M phase, resulting from the disappearance of the blocking effect of CDDP with time. Judging from these sequential changes in vivo, a second drug with specific cytocidal effect on S phase cells should work best 48hr after the initial CDDP therapy, and drugs specific to G₂+M phase or radiotherapy should be added at 72hr. Such preclinical experiments may be useful in the design of combination chemotherapy regimens against human neuroblastoma.

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