Insulin-like growth factor-II (IGF-II) is a potent mitogen for several types of cultured cells and tissues. We have studied the interaction of IGF-II with a panel of cultured human breast cancer cell lines, examining the possibility that these cells synthesize and secrete IGF-II activity which could have autocrine/paracrine functions. Synthetic IGF-II was mitogenic in five of seven cell lines tested, including the estrogen receptor-positive lines MCF-7L, ZR75-1, and T47D and the estrogen receptor (ER)-negative lines Hs578T and MDA-231. IGF-II was slightly less potent than IGF-I in stimulating DNA synthesis in MCF-71 cells, an effect that paralleled its ability to compete for [125I]IGF-I binding in these cells. Affinity labeling studies revealed that IGF-II could also compete for binding to the 130,000 mol wt alpha-subunit of the IGF-I receptor. A monoclonal antibody to the IGF-I receptor inhibited the mitogenic effects of IGF-II in MCF-7L and MDA-231 cells, suggesting that this receptor mediates the growth effects of IGF-II in these breast cancer cells. Using a RIA and a RRA, IGF-II-like activity was detected in conditioned medium extracts processed to remove IGF-binding proteins from several breast cancer cell lines, with the highest levels found in conditioned medium from MCF-7L and T47D cell lines. IGF-II mRNA transcripts in MCF-7L and T47D cells were identified by Northern blot analysis and were confirmed by RNase protection assay. IGF-II mRNA was increased by estrogen in MCF-7L cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of purifed bovine and human growth hormone were tested in vitro with murine and human bone marrow by means of granulocyte-monocyte and erythroid progenitor cloning techniques. Nanogram concentrations of the growth hormones potentiated erythropoietin-stimulated erythropoiesis, but not granulopoiesis, in a species-specific manner.

O-Endorphin, an opiate-like peptide, has potent antinociceptive properties when it is administered directly into the brain and assayed in the tail-flick, hot-plate, and writhing tests in mice and in the wet shake test in rats. On a molar basis, O-endorphin is 18 to 33 times more potent than morphine and its actions are blocked by the specific opiate antagonist, naloxone hydrochloride. The activity of f-endorphin in vivo is also compared to other peptides that show opiate-like activity in assays in vitro. The existence of endogenous ligands for the opiate receptor in the brain has been suggested by Collier (1) and Goldstein (2). In searching for such ligands, Terenius and Wahlstrom (3) and Hughes (4), using the receptor binding assay and bioassays with mouse vas deferens and guinea pig ileum, independently found opiate-like substances in the brain. Subsequently, Hughes et al. (5) purified and characterized two opiate-like peptides, termed enkephalins, which have the following amino acid sequences: H-Tyr-Gly-Gly-Phe-Met-OH and H-Tyr-Gly-GlyPhe-Leu-OH. Other workers (6, 7) have confirmed the results of Hughes et al. Concurrently, Goldstein and his associates (8,9) found opiate-like materials in a crude preparation of corticotropin (ACTH). Synthetic corticotropin and a-melanotropin lacked similar activity. Upon purification and characterization, the corticotropin contaminant was shown to be a peptide with a molecular weight of approximately 1750. Recently, Li and Chung (10) isolated and determined the sequence of an untriakontapeptide from camel pituitary gland. This peptide, named fl-endorphin, has been synthesized (11) and shown to possess opiate-like activity in receptor binding assays and in the guinea pig ileum bioassay (10-12).In the isolation and identification of opiate-like peptides from brain and pituitary tissue, the criteria for specific activity has been based on bioassays in vitro. Information on the pharmacological properties of these peptides in vivo is lacking, partly due to the scarcity of purified or synthetic materials. In this article, we report on the relative analgesic properties of fiendorphin and related peptides when assayed in the mouse and rat in uivo. MATERIALS AND METHODSMale ICR mice weighing 25-30 g (Simonsen Laboratories, Gilroy, Calif.) and male Sprague-Dawley rats weighing 250-350 g were used in all the experiments.Methionine-enkephalin was purchased from Bachem Laboratories (Marina del Reyes, Calif). f,-Endorphin was synthesized as previously described (11). fl-Lipotropin (LPH) was isolated from sheep pituitary glands by the procedure described by Li et a!. (13 With 2-fold increase in latency of reaction time as a quantal index of inhibition, the median antinociceptive dose (AD50) and 95% confidence limits were calculated according to the method of Litchfield and Wilcoxon (20). At least eight animals were tested at each dose with three to five dose levels used for determining the ADs,0.Writhing Test in Mice. When "analgesia" was measured by the writhing method (17), acetic...

Although insulin-like growth factor-I (IGF-I) and insulin have been shown to augment rat granulosa cell differentiation, their mechanism(s) of action has not yet been elucidated. In the present study, we have examined granulosa cells obtained from immature hypophysectomized estrogen-treated rats for specific IGF-binding sites that might mediate the effects of the insulin-like peptides. Using synthetic [125I]iodo-IGF-I, we have found specific high affinity, low capacity (Kd = 1.36 +/- 0.131 nM; 3250 +/- 662 sites/cell) IGF-I-binding sites that have lower affinities for the related peptides IGF-II and insulin (potency ratio, 1:9:700 for IGF-I, IGF-II, and insulin). We have also found specific binding sites for [125I]iodo-IGF-II, a newly available synthetic peptide. The IGF-II-preferring sites were of a single class (Kd = 1.54 +/- 0.32 nM; 4728 sites/cell) and exhibited a rank competition order of IGF-II greater than IGF-I much greater than insulin. To study the functional correlates of these binding activities, granulosa cells were cultured for 2 days in serum-free medium in the presence of FSH, with or without increasing concentrations of IGF-I, IGF-II, or insulin. Medium steroids were then determined by specific RIA, and cellular LH/hCG receptors were measured by specific [125I]iodo-hCG binding. Treatment with FSH increased estrogen and progestin production and induced the formation of LH/hCG receptors. Concomitant treatment with the three peptides dose-dependently enhanced both FSH-stimulated steroidogenesis and LH/hCG receptor induction, with a rank order of potency of IGF-I greater than IGF-II greater than insulin (potency ratio, 1:8:36). This rank order of potency of the insulin-like peptides was more closely correlated with their ability to compete for IGF-I binding rather than IGF-II binding, suggesting the preferential involvement of IGF-I receptors in the ovarian actions of the IGFs, although the involvement of IGF-II and insulin receptors cannot be dismissed. Our results demonstrate, for the first time, a biological action of synthetic IGF-II in granulosa cells and further show a novel insulin effect, enhancement of LH/hCG receptor induction. These findings also indicate that rat granulosa cells possess specific IGF-I and IGF-II-binding sites that may mediate the gonadotropin-enhancing actions of the insulin-like peptides. Since IGF-I appears to be the most biologically potent peptide, it is likely to be the most important insulin-like peptide involved in granulosa cell differentiation in vivo.