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Query: UMLS:C0598934 (tumor growth)
 58,965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of various fetal tissues and transplantable tumors in syngeneic newborn and adult mice [BALB/c, DBA/2, and (CBA X C57BL/6J)F1] was compared. Fetal skin, a mixture of all fetal tissues, and tumors were transplanted. The tumors arose spontaneously [hepatomas, mammary gland adenocarcinoma (MGAC)] or resulted from malignant conversion of ectopic transplants either of fetal tissues (urinary bladder carcinoma, adenocarcinoma of small intestine, stomach sarcoma) or of adult animal tissues (ovarian carcinoma) in the syngeneic system. The growth of fetal skin transplants and teratomas, which developed after transplantation of minced tissue from 18- to 20-day and 12- to 14-day fetuses, was considerably inferior in newborn syngeneic recipients, as compared with similar transplants in adults. Inhibition of tumor growth observed in newborn animals was manifested in prolongation of latent period before tumor node appearance and in slowing of growth rate of developed tumors. One of six tumors studied (MGAC) grew at the same rate in newborn and adult recipients. It was suggested that a special type of cellular and/or humoral mechanisms controlling tumor growth exists in newborns. The activity of such factors was conceivably based on fetal tumor antigens as targets. We assumed that weakly antigenic and strongly antigenic tumors behaved differently in respect to nonimmune and immune surveillance mechanisms.
J Natl Cancer Inst 1976 Jul
PMID:Nonimmune and immune surveillance. I. Growth of tumors and normal fetal tissues grafted into newborn mice. 18 65

Various attempts were made to assess the role of the mononuclear phagocyte system in tumor resistance of rats in vivo. The growth of sc inoculated, weakly immunogenic, carcinogen-induced, syngeneic tumor cells was modestly reduced by ip injection and, more impressively, by local injection of peptone-induced, activated, nonimmune macrophages. A single iv injection of silica particles or carrageenan on the day of sc tumor cell inoculation greatly enhanced tumor growth. When these agents had been given a few days before or after tumor cell inoculation, the tumor-promoting efficiency was distintly diminished or even cancelled. The enhancing effects of silica and carrageenan on tumor growth were nulified by the macrophage-stabilizing agent, poly-2-vinylpyridine N-oxide, To assess the in vivo consequences of silica administration, various cellular, biochemical, and functional macrophage parameters were determined at different intervals. Results indicated the complexity of events elicited after the mononuclear phagoycte system was damaged, which made the interpretation of such results difficult.
J Natl Cancer Inst 1976 Dec
PMID:Promotion of tumor growth in vivo by antimacrophage agents. 18 4

The S-adenosylmethionine synthetase activities of rat liver and Novikoff ascites tumor have been partially purified and characterized by chromatographic behavior, kinetic analysis, sulfhydryl dependency, and response to inhibitors. We have shown that the tumor contains a single form of the enzyme, with a Km (methionine) of 21 muM, and that the liver contains two isofunctional forms, a minor form with a Km (methionine) of 21 muM, as well as a major form with a Km of 1 mM. The tumor contained more of the low Km form of the enzyme than the liver, although the total enzyme activity of liver (measured at high substrate concentrations) exceeded that of the tumor severalfold. The tumor enzyme also corresponded to the minor form of liver enzyme in elution position from Sephadex G-150 and diethylamino-ethyl cellulose, and both had a Km (adenosine 5'-triphosphate) of 0.14 mM. The tumor enzyme differed from the major form of the liver enzymes in elution position, and the Km (adenosine 5'-triphosphate) for the latter was 1.5 mM. In contrast to the major liver enzyme, the tumor enzyme did not appear to require sulfhydryl agents for the activity to be detected, was inhibited by S-adenosylmethionine, and was inhibited to a greater degree by tripolyphosphate. It is suggested that the two forms of the enzyme are involved in the production of S-adenosylmethionine for different biological functions, and their different properties may allow selective inhibition of tumor growth by chemotherapeutic agents.
Cancer Res 1977 Feb
PMID:Partial purification and characterization of tumor and liver S-adenosylmethionine synthetases. 18 46

Specific iodine-125-labeled prolactin binding was measured in membrane particles prepared from R3230AC mammary carcinoma and liver of tumor-bearing Fischer rats after either prolactin, estrogen, or lergotrile mesylate treatment, or after the induction of diabetes by streptozotocin. Hormone binding to tumors was decreased by treatment with prolactin (.5 or 1 mg/day) or estradiol valerate (7.5 mg/kg/week). In contrast, prolactin treatment was without affect on prolactin binding to liver membrane particles, but estradiol valerate treatment resulted in a 4-fold increase in prolactin binding to this tissue. Lergotrile mesylate, which lowers plasma prolactin levels, had no affect on tumor growth or prolactin binding to either tumor or liver. Prolactin binding to both tumor and liver was significantly reduced in diabetic rats, suggesting that insulin may play an important role in controlling tissue sensitivity to prolactin. Specific binding of iodine-labeled prolactin to enzymatically dissociated cells from R3230AC tumors was demonstrated in vitro. The binding capacity of the cells was found to be of the same order of magnitude as the binding capacity in membrane preparations when appropriate corrections were applied for yields of cells and membranes. R3230AC tumor, which is responsive to prolactin, appears therefore to be a useful model system for further study aimed at elucidation of growth and metabolic response to the hormone prolactin in breast cancer.
Cancer Res 1977 Feb
PMID:Prolactin binding to R3230AC mammary carcinoma and liver in hormone-treated and diabetic rats. 18 51

Diethylnitrosamine (DENA) hepatocarcinogenesis was enhanced by sequential exposure with polychlorinated biphenyls (PCBs) and with phenobarbital. This was shown by the earlier appearance of tumors and a significant increase in the number of tumors. However, there was no evidence suggesting an acceleration of tumor growth.
Cancer Lett 1976 Sep
PMID:Enhancement of diethylnitrosamine hepatocarcinogenesis in rats by exposure to polychlorinated biphenyls or phenobarbital. 18 5

The rates of urea synthesis in rat liver and in a series of rat liver neoplasms with widely different growth rates and degree of differentiation were investigated using tissue slices incubated in a Krebs-Ringer bicarbonate buffer. Urea synthesis did not occur in fast-growing, poorly differentiated Novikoff and Morris 3924A hepatomas, but it did occur in slow-growing, well- and highly differentiated hepatomas; however, there was no correlation with growth rate or degree of differentiation. Urea synthesis was comparable with normal liver, at about 32 mumoles/hr/g tissue, in the slow-growing Morris hepatomas 21, 28A, 47C, and 44; but it was very low in two other slow-growing, highly differentiated hepatomas, 9618A and 20. The well-differentiated Morris hepatoma 5123C had intermediate levels of urea synthesis. This pattern of urea synthesis closely paralleled the previously reported activity of carbamyl phosphate synthetase in these tumors. The rate of urea synthesis was normal in livers of Buffalo rats bearing fast- or slow-growing hepatomas in low urea synthesis rates, but it was markedly lowered in the livers of rats bearing large, slow-growing tumors with high urea synthesis rates. Urea synthesis in liver declined as the tumors increased in size. The total rate of urea synthesis in liver and tumor, as well as the concentrations of urea in the serum and urine of tumor-bearing animals, remained remarkably constant throughout the period of tumor growth, suggesting the existence of a homeostatic mechanism that controls the urea cycle activity in accordance with the synthetic activity of the tumor. In parabiotic animals, carbamyl phosphate synthetase activity and urea synthesis were lowered in the host livers of partners bearing tumors with high carbamyl phosphate synthetase- and urea-synthetic activity, but there was no significant effect on urea cycle activity in the normal partners. This result discounts the likelihood of a circulating humoral factor that controls hepatic urea cycle activity.
Cancer Res 1977 Mar
PMID:Urea synthesis in Novikoff and Morris hepatomas. 18 16

The activity of estrogen 16alpha-hydroxylase was measured for nine Morris hepatomas of different growth rates and host livers. Activity was measured in the microsomal fraction of the cell (100,000 X g). In the spectrum of hepatomas studied, 16alpha-hydroxylase activity was significantly decreased in parallel with the increase in hepatoma growth rate. The decrease in enzymic activity ranged from 16 to 19% for the slow-growing tumors (Hepatomas 44, 28A, and 9633), 2 to 9% for the intermediate-growing tumors (Hepatomas 38B, 7795, and 5123A), and 0% for the fast-growing tumors (Hepatomas 7288C, 7777, and 42A). Estrogen 16alpha-hydroxylase activity of the liver of tumor-bearing rats differed from that of liver of healthy animals. There was a decrease in enzymic activity ranging from 66% to 90% of normal control rats. The activity level of the host liver did not correlate with tumor growth rate. Stimulation of 16alpha-hydroxylase with phenobarbital showed a 4-fold increase in activity in normal liver and only a 2- to 3-fold increase in host livers. The slow- and intermediate-growing hepatomas showed a 1.2-to 1.4-fold increase in enzyme activity, and no activity or stimulation in the fast-growing hepatomas was observed.
Cancer Res 1977 Apr
PMID:Metabolism of estrogens in hepatomas of different growth rates. 19 Nov 75

The effect of prolactin in supporting the growth of 7, 12-dimethylbenz(a)anthracene-induced mammary tumor in adult female Sprague-Dawley rats was investigated when estrogen receptors were blocked by the nonsteroidal antiestrogen, Tamoxifen, ICI 46,474. Following an oophorectomy-induced remission, perphenazine, which stimulates endogenous prolactin release, was able to restore tumor growth whether or not Tamoxifen was added. A second course of perphenazine treatment, instituted after the tumors were allowed to shrink, was again effective in stimulating tumor growth. After a regression in tumor size induced by oophorectomy and daily administration of Tamoxifen, perphenazine was able to restore original tumor size despite continued treatment with Tamoxifen. In intact rats, after regression was obtained by daily administration of Tamoxifen and the prolactin inhibitor, lergotrile mesylate, perphenazine induced tumor growth when the latter was discontinued, even though Tamoxifen was continued for 50 days. Estrogen receptors measured at the time of maximum stimulation by perphenazine were undetectable. On the other hand, estradiol did not stimulate tumor growth when serum prolactin was depressed to undetectable levels by lergotrile. These results indicate that prolactin supports the growth of 7, 12-dimethylbenz(a)anthracene-induced rat mammary tumor and that estrogen receptors are not required under these conditions.
Cancer Res 1977 Apr
PMID:Predominant role of prolactin in stimulating the growth of 7, 12-dimethylbenz(a)anthracene-induced rat mammary tumor. 19 Nov 82

Some of the regulatory mechanisms of cyclic adenosine monophosphate (AMP) production in human brain tumors were investigated by assessing both cyclic AMP levels and adenyl cyclase activity. A large disparity was found between the levels of cyclic AMP of normal brain and brain-tumor tissue. Cyclic AMP levels were much lower in brain tumors (25.8 pmoles (picomoles)/mg protein) than in normal brain (98.8 pmoles/mg protein). These studies also show that the abnormally low levels of cyclic AMP in tumors parallel those of adenyl cyclase. The mean adenyl cyclase activity of brain tissue was found to be 111.0 pmoles of cyclic AMP/min/mg protein, while that of the tumor was only 23.0 pmoles/min/mg protein. Levels of cyclic AMP and adenyl cyclase activity were inversely related to the degree of malignancy. Attempts to stimulate adenyl cyclase in homogenates of human brain and brain tumors resulted in a similar response in both tissues. Norepinephrone was the most effective stimulant and produced a two- to threefold increase in cyclic AMP production, while histamine had no effect. It is concluded that one of the factors governing tumor growth may be a defect in the adenyl cyclase system.
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PMID:Cyclic AMP and adenyl cyclase in brain tumors. 19 76

Cytotoxic effector T-lymphocytes were produced in vitro by sensitization of spleen cells on monolayers of syngeneic macrophages that had been fed with radiation leukemia virus-containing cell extracts or with supernatants of virus-producing cell cultures. The sensitized lymphocytes were cytotoxic to cell lines that expressed viral antigens. Secondary mouse embryo fibroblasts were little affected. Sensitization via macrophages appeared to be a useful system for identification of viral antigens on surfaces of various target cells, as well as for tests of the protective effect of such lymphocytes against tumor growth in vivo.
J Natl Cancer Inst 1977 May
PMID:Macrophage-mediated in vitro sensitization of T-lymphocytes. I; Detection of murine leukemia virus-associated antigens. 19 5


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