Effects of purine cyclic nucleotides on the growth of neonatal rat hepatocytes in primary tissue culture

Armato, Ubaldo; Draghi, E.; Andreis, P. G.

doi:10.1016/0014-4827(77)90132-x

Cited by 32 publications

(4 citation statements)

References 15 publications

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“…Furthermore, under similar conditions, we have found a dose-dependent stimulation of DNA-synthesis by dibutyryl cyclic Ah4P (1O-9-1O-5 mol/l; Brdnstad, Sand, Christoffersen, unpublished). Stimulatory effects of low concentrations of cyclic AMP have also been found in fetal hepatocytes [29].…”

Section: Biphasic Effect Of Isoprenaline On Dna-synthesis In Culturedmentioning

confidence: 96%

Increased effect of adrenaline on cyclic AMP formation and positive β‐adrenergic modulation of DNA‐synthesis in regenerating hepatocytes

Brønstad

Christoffersen

1980

FEBS Letters

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Section: Biphasic Effect Of Isoprenaline On Dna-synthesis In Culturedmentioning

confidence: 96%

Increased effect of adrenaline on cyclic AMP formation and positive β‐adrenergic modulation of DNA‐synthesis in regenerating hepatocytes

Brønstad

Christoffersen

1980

FEBS Letters

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“…Numerous in vitro studies have shown cAMP to be growth promoting for mouse, rat, and human mammary epithelia (1)(2)(3)(4) and for a variety of other epithelial cell types (5)(6)(7)(8). In situ, cAMP levels increase as the mammary gland grows during pregnancy (9,10), and they are elevated in several breast carcinomas (11,12).…”

mentioning

confidence: 99%

“…Numbers of glands treated are shown in parentheses; error bars represent 95% confidence intervals. The following criteria were used to score glands: 0, ductal tips are same diameter as subtending ducts, which are spindly; +1, some but not all duct tips are enlarged, no end buds, ductal diameter is unaffected; +2, small end buds are present, enlarged tips, ductal diameter is increased; +3, larger end buds are present but they are few in number (<10), ductal diameter is increased; +4, numerous end buds (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) are present but some tips remain unstimulated, ductal diameter is comparable with that of hormonally intact animal; +5, entire gland appears stimulated, many end buds (>20) are present; +6, as in +5 but the gland is intensely stimulated in places with "grape cluster" outgrowths on some ducts.…”

mentioning

confidence: 99%

In vivo, cAMP stimulates growth and morphogenesis of mouse mammary ducts.

Silberstein¹,

Strickland²,

Trumpbour³

et al. 1984

Proc. Natl. Acad. Sci. U.S.A.

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In culture, cAMP is known to be mitogenic for mammary cells and several other epithelia, but evidence for a similar role in vivo has been only correlative. We have used plastic implants to cause slow release of cholera toxin and other cAMP-active agents to local areas of mammary glands in ovariectomized mice. Elevated levels of intracellular cAMP around the implants promoted vigorous growth and normal ductal morphogenesis, while distant sites were unaffected. Local effects of cAMP included restoration of normal ductal caliber, formation of new end buds, and reinitiation of DNA synthesis in both epithelium and surrounding stroma. Thus, cAMP is both a mitogenic and a morphogenetic factor in this tissue.Numerous in vitro studies have shown cAMP to be growth promoting for mouse, rat, and human mammary epithelia (1-4) and for a variety of other epithelial cell types (5-8). In situ, cAMP levels increase as the mammary gland grows during pregnancy (9, 10), and they are elevated in several breast carcinomas (11,12). To obtain more direct evidence as to whether cAMP may function as an intracellular mediator of hormone or growth factor action in the mammary gland, we investigated the effects of raising cAMP levels in small regions of the mouse mammary gland by using slow-release plastic implants.End buds, the primary sites of mammary epithelial proliferation in subadult virgin mice, are complex highly mitotic structures comprised of the stem cell progenitors of myoepithelial and ductal cells (13). As the growth points for the ductal tree, end buds are the focus of mammary growth regulatory influences during this stage in development of the gland (14). We here present evidence that, in situ, local elevation of cAMP stimulated formation of new end buds in regressed ducts, apparently replacing the normal hormonal requirements for this type of development. CT Dosage. Commercial CT contains 4.8% by weight of toxin protein, the bulk of the preparation being NaCl and Tris HCl (55% and 37.6%, respectively). The most commonly used implant was prepared with 1 mg of the commercial preparation dissolved in 0.25 ml of Elvax. The dried Elvax pellet weighed -40 mg and contained 48 ,ug of toxin protein or 1.2 ,ug in an implant-sized piece weighing 1 mg. The useful dose range for this implant type is 0.1-1.2 ,ug of toxin. MATERIALS AND METHODSRelease of CT from Elvax. The release kinetics of CT was studied in vitro. Pellets prepared with either 1 mg or 10 mg of the toxin were cut into implant-sized pieces, weighed, and sealed in nylon bags (Nitex), which were then placed in 1.5 ml of normal saline at 37°C on a rotator (1 rpm). At 24-hr intervals, the bags were removed and the saline was assayed for protein against a CT standard using the Bradford method (16). Bags were then rinsed and replaced in fresh saline. An adequate amount of Elvax with toxin was available for three trials, one of which is shown here (Fig. 5); the release profile was the same for all three trials. Surgical Implantation. The abdominal skin of Nembutalanesthet...

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“…The cultures were labeled for 24 h with 0.5 pCiiml [3H]TdR and then fixed with methano1:acetate (9: 1). The polyethylene disks were then detached from the flasks and attached, cell-side upward, to glass slides with a drop of 4% wiv gum acacia and processed for autoradiography according to Armato et al (1977).…”

Section: Dna Synthesismentioning

confidence: 99%

Extracellular calcium modulates prereplicative cyclic AMP surges in EGF‐stimulated primary neonatal rat Hepatocytes

Armato

Ribecco

Guerriero

et al. 1994

Journal Cellular Physiology

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The cells in nearly pure (96-98%) primary cultures of hepatocytes from neonatal rat liver in high (1.0 mM)-Ca2+, serum-free, synthetic HiWo5Ba2000 medium initiated DNA synthesis and entered mitosis between 11 and 30 h after the addition of 10 ng/ml EGF. During the 10-h prereplicative period, the cultured hepatocytes, like regenerating rat liver cells, generated two large cyclic AMP transients, one peaking between 30 min and 2 h and the other around 6 h. Hepatocytes stimulated by the same concentration of EGF in low (0.02 mM)-Ca2+ medium increased cyclic AMP synthesis as much as the EGF-treated hepatocytes in high-Ca2+ medium, but they released the additional cyclic AMP into the medium and could not generate prereplicative internal cyclic AMP surges, initiate DNA replication, or enter mitosis. These results suggest that one of the ways external Ca2+ controls prereplicative development of hepatocytes is to restrain the release of cyclic AMP and thus enable the cell to accumulate enough internal cyclic AMP to stimulate events required to initiate DNA replication.

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Effects of purine cyclic nucleotides on the growth of neonatal rat hepatocytes in primary tissue culture

Cited by 32 publications

References 15 publications

Increased effect of adrenaline on cyclic AMP formation and positive β‐adrenergic modulation of DNA‐synthesis in regenerating hepatocytes

Increased effect of adrenaline on cyclic AMP formation and positive β‐adrenergic modulation of DNA‐synthesis in regenerating hepatocytes

In vivo, cAMP stimulates growth and morphogenesis of mouse mammary ducts.

Extracellular calcium modulates prereplicative cyclic AMP surges in EGF‐stimulated primary neonatal rat Hepatocytes

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