Growth arrest and morphological change of human breast cancer cells by dibutyryl cyclic AMP and L-arginine.

The growth in vitro of human breast cancer cells, line MCF-7, was inhibited by a daily supplement of L-arginine (1 milligram per milliliter). Arginine acted synergistically with dibutyryl adenosine 3',5'-monophosphate (cyclic AMP) (10(-6) molar) to enhance the growth inhibitory effect: the cell replication ceased completely within 2 days after treatment. The growth arrest accompanied a change in cell morphology and was preceded by increases in the cellular concentration of cyclic AMP, adenylate cyclase, and type II cyclic AMP-dependent protein kinase activities as well as a decrease of estrogen binding activity. The results suggest that growth of human breast cancer cells is subject to cyclic AMP-mediated regulation and that arginine may play a specific role in this process.

Relationship of hormone dependency to estrogen receptor and adenosine 3',5'-cyclic monophosphate-binding proteins in rat mammary tumors.

Estrogen-binding activity and the binding activity of adenosine 3',5'-cyclic monophosphate (cAMP) were assayed in the cytosol of biopsy specimens from 70 rat mammary tumors. The response of these tumors to host ovariectomy was followed. The hormone dependency of the tumors was closely related to the relative concentrations of estrogen receptor (ER) and cAMP-binding protein (CR) in the tumor cytosol. When ER and CR were expressed as the ER/CR ratio, 36 of 38 (95%) hormone-dependent tumors had ratios of 35 X 10(-3) or more, whereas 31 of 32 (97%) hormone-independent tumors had ratios of less than 35 X 10(-3). When ER alone was measured, hormone dependency could be correctly predicted in only 60% of the tumors because the ER range for individual tumors of both types greatly overlapped. Ratios of ER/CR were also elevated in normal estrogen target tissues as compared to those in normal estrogen nontarget tissues. Thus determination of the ER/CR ratio in tumor cytosols appeared to be a more reliable method of predicting hormone dependency than was determination of ER alone.

Cyclic adenosine 3',5'-monophosphate-binding protein: role in ovariectomy-induced regression of a hormone-dependent mammary tumor in Sprague-Dawley female rats.

Cyclic AMP- and estrogen-binding activities were present in 7,12-dimethylbenz[a]anthracene-induced mammary carcinomas in Sprague-Dawley female rats. Soon after ovariectomy of the host, cyclic AMP binding markedly increased and estrogen binding decreased in regressing tumors. These changes were reversed when tumor growth was resumed following the injection of estradiol-17beta. The data suggested the possible involvement of cyclic AMP binding in the growth control of a hormone-dependent mammary tumor.

Requirement of essential fatty acids in the diet for development of the mouse mammary gland.

The ductal system of mammary glands in C3H mice that were started on diets deficient in essential fatty acid(s) (EFA) 1--2 weeks after weaning developed at a normal rate. The alveolar structures, however, began to disappear in the mice after 17 weeks on the EFA-deficient regimen. Injection sc of linoleic acid prevented the atrophic process. Alveoli were also absent in the glands of multiparous mice that were maintained for 32 weeks on the EFA-deficient diet. When the EFA-deficient regimen was started in females during midpregnancy and maintained continuously thereafter, both ductal and alveolar structures failed to develop in the mammary glands of the offspring. Linoleic acid appears to be required for development of ductal and alveolar structures during growth of the mammary gland and also for maintenance of the alveolar structures in the adult mammary gland.

Regression of hormone-dependent mammary tumors in Sprague-Dawley rats as a result of tamoxifen or pharmacologic doses of 17 beta-estradiol: cyclic adenosine 3',5'-monophosphate-mediated events.

The estrogen and cyclic adenosine 3',5'-monophosphate (cAMP)-binding activities changed markedly when 7,12-dimethylbenz[a]anthracene-induced mammary tumors of Sprague-Dawley rats regressed following daily injections of either tamoxifen or pharmacologic doses of 17 beta-estradiol. cAMP binding increased eightfold to tenfold, whereas estrogen binding increased twofold to threefold in regressing tumor nuclei at 5 days after either treatment, which resulted in an inversion of the ratio of estrogen binding to cAMP binding found in growing tumor nuclei. Concomitantly, both binding activities were depleted from the cytosol. In the regressing tumors, the cAMP level increased twofold and nuclear cAMP-dependent protein kinase activity increased threefold to fourfold, with a 70-80% decrease in the cytoplasmic protein kinase activity. The rise in the nuclear protein kinase activity was abolished when cycloheximide was given with tamoxifen or with high doses of 17 beta-estradiol, which suggests that the increased activity is due to new protein synthesis. In the regressing tumor nuclei, the phosphorylation of the regression-associated proteins increased, whereas the phosphorylation of growth-associated proteins decreased. These data suggest that the mammary tumor regression induced by tamoxifen or high doses of estrogen proceed through a series of cAMP-mediated events.

Inverse relation between estrogen receptors and cyclic adenosine 3':5'-monophosphate-binding proteins in hormone-dependent mammary tumor regression due to dibutyryl cyclic adenosine 3':5'-monophosphate treatment or ovariectomy.

During the growth arrest of 7,12-dimethylbenz(alpha) anthracene-induced rat mammary carcinomas following ovariectomy or N6, O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (DBcAMP) treatment, a change in the specific estrogen and cAMP binding to tumor proteins is observed. Three days after ovariectomy or DBcAMP treatment of the hosts, cAMP binding increases 5- and 2-fold in the nuclei and cytosol of tumors, respectively, whereas nuclear and cytoplasmic estrogen binding decreases by 70 and 25%, respectively. These changes in cAMP- and estrogen-binding activities are detectable within 1 day after ovariectomy or DBcAMP treatment, and the changes are reversed when resumption of tumor growth is induced by the injection of estradiol valerate or cessation of DBcAMP treatment. When 7,12-dimethylbenz(alpha)anthracene-induced tumors fail to regress after ovariectomy or DBcAMP treatment, the change in estrogen and cAMP binding does not occur. Concomitant with the increase of cAMP-binding activity in regressing tumors are increases in histone kinase activity and the cAMP content of the tumors. These increases in cAMP-binding and protein kinase activities are blocked by cycloheximide. These data suggest an interaction between a steroid hormone and cAMP in the growth control of a hormone-dependent mammary tumor.

Cyclic AMP-binding proteins: inverse relationship with estrogen-receptors in hormone-dependent mammary tumor regression.

Dimethylbenzanthracene-induced rat carcinomas possess activities binding cyclic adenosine 3':5'-monophosphate (cAMP) and estrogen. When dimethylbenzanthracene-induced tumors regress after ovariectomy of the host, a change in the specific binding of cAMP and estrogen occurs in the tumors. Six days after ovariectomy, cAMP binding increases 5-fold in the nuclei and 2-fold in the cytosol of tumors, while nuclear and cytoplasmic estrogen binding decreases by 80% and 50%, respectively. These changes in activities binding cAMP and estrogen are detectable within 1 day after ovariectomy and the changes are reversed when resumption of tumor growth is induced by the injection of 17beta-estradiol. When dimethylbenzanthracene-induced tumors fail to regress after ovariectomy, the change in activities binding cAMP and estrogen does not occur. Significant increases in the cAMP level as well as in adenylate cyclase and cAMP-phosphodiesterase activities are also found in the regressing tumors. Concomitant with the increase of cAMP-binding activity is an increase in histone kinase activity in the regressing tumor. These data suggest the involvement of cAMP in the growth control of a hormone-dependent mammary rumor.

Role of Agrobacterium cell envelope lipopolysaccharide in infection site attachment.

Lipopolysaccharide (LPS) isolated from Agrobacterium tumefaciens inhibited tumor induction by virulent bacteria. LPS from site-binding strains was not effective if added to the plant wound shortly after the bacteria, and LPS from avirulent, non-site-binding strains of Agrobacterium was not inhibitory regardless of the order of addition. However, LPS and whole cells of avirulent strains NT1 and IIBNV6, which lack of Agrobacterim virulence plasmid, were inhibitory. Chromosomal deoxyribonucleic acid thus determines specificity of this essential component of the Agrobacterium infection process.