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P Scalia

Publications and source records attributed to P Scalia.

15 recordsLinked to original sources
PubMed2001

Regulation of the Akt/Glycogen synthase kinase-3 axis by insulin-like growth factor-II via activation of the human insulin receptor isoform-A.

Insulin-like growth factor II (IGF-II) plays a key role in mitogenesis during development and tumorigenesis and is believed to exert its mitogenic functions mainly through the IGF-I receptor. Recently, we identified the insulin receptor isoform A (IR(A)) as an additional high affinity receptor for IGF-II in both fetal and cancer cells. Here we investigated the mitogenic signaling of IGF-II via the Akt/Glycogen synthase kinase 3 (Gsk3) axis employing R-IR(A) cells that are IGF-I receptor null mouse embryonic fibroblasts expressing the human IR(A). IGF-II induced activation of the proto-oncogenic serine kinase Akt, reaching maximal at 5-10 min. IGF-II also caused the rapid and sustained deactivation of glycogen synthase kinase 3-beta (Gsk3beta), reaching maximal at 1-3 min, shortly preceding, therefore, maximal activation of Akt. Under our conditions, IGF-II and insulin induced 70-80% inhibition of Gsk3betaactivity. In these cells IGF-II also deactivated Gsk3alpha although less effectively than Gsk3beta. In parallel experiments, we found that IGF-II induced transient activation of extracellular-signal-regulated kinases (Erk) reaching maximal at 5-10 min and decreasing thereafter. Time courses and potencies of regulation of both mitogenic pathways (Akt/Gsk3beta and Erk) by IGF-II via IR(A) were similar to those of insulin. Furthermore, IGF-II like insulin effectively stimulated cell cycle progression from the G0/G1 to the S and G2/M phases. Interestingly, AP-1-mediated gene expression, that was reported to be negatively regulated by Gsk3beta was only weakly increased after IGF-II stimulation. Our present data suggest that the coordinated activation or deactivation of Akt, Gsk3beta, and Erk may account for IGF-II mitogenic effects and support an active role for IR(A) in IGF-II action.

Animals↗
PubMed1999

Insulin receptor activation by IGF-II in breast cancers: evidence for a new autocrine/paracrine mechanism.

IGF-II, produced by breast cancer epithelial and stromal cells, enhances tumor growth by activating the IGF-I receptor (IGF-I-R) via autocrine and paracrine mechanisms. Previously we found that the insulin receptor (IR), which is related to the IGF-I-R, is overexpressed in breast cancer cells. Herein, we find that, in breast cancer the IR is activated by IGF-II. In eight human breast cancer cell lines studied there was high affinity IGF-II binding to the IR, with subsequent IR activation. In these lines, IGF-II had a potency up to 63% that of insulin. In contrast, in non malignant human breast cells, IGF-II was less than 1% potent as insulin. Via activation of the IR tyrosine kinase IGF-II stimulated breast cancer cell growth. Moreover, IGF-II also activated the IR in breast cancer tissue specimens; IGF-II was 10-100% as potent as insulin. The IR occurs in two isoforms generated by alternative splicing of exon 11; these isoforms are IR-A (Ex11-) and IR-B (Ex11+). IR-A was predominantly expressed in breast cancer cells and specimens and the potency of IGF-II was correlated to the expression of this isoform (P<0.0001). These data indicate, therefore, that the IR-A, which binds IGF-II with high affinity, is predominantly expressed in breast cancer cells and represents a new autocrine/paracrine loop involved in tumor biology.

Binding, Competitive↗
PubMed1999

Insulin receptor isoform A, a newly recognized, high-affinity insulin-like growth factor II receptor in fetal and cancer cells.

Insulin-like growth factor II (IGF-II) is a peptide growth factor that is homologous to both insulin-like growth factor I (IGF-I) and insulin and plays an important role in embryonic development and carcinogenesis. IGF-II is believed to mediate its cellular signaling via the transmembrane tyrosine kinase type 1 insulin-like growth factor receptor (IGF-I-R), which is also the receptor for IGF-I. Earlier studies with both cultured cells and transgenic mice, however, have suggested that in the embryo the insulin receptor (IR) may also be a receptor for IGF-II. In most cells and tissues, IR binds IGF-II with relatively low affinity. The IR is expressed in two isoforms (IR-A and IR-B) differing by 12 amino acids due to the alternative splicing of exon 11. In the present study we found that IR-A but not IR-B bound IGF-II with an affinity close to that of insulin. Moreover, IGF-II bound to IR-A with an affinity equal to that of IGF-II binding to the IGF-I-R. Activation of IR-A by insulin led primarily to metabolic effects, whereas activation of IR-A by IGF-II led primarily to mitogenic effects. These differences in the biological effects of IR-A when activated by either IGF-II or insulin were associated with differential recruitment and activation of intracellular substrates. IR-A was preferentially expressed in fetal cells such as fetal fibroblasts, muscle, liver and kidney and had a relatively increased proportion of isoform A. IR-A expression was also increased in several tumors including those of the breast and colon. These data indicate, therefore, that there are two receptors for IGF-II, both IGF-I-R and IR-A. Further, they suggest that interaction of IGF-II with IR-A may play a role both in fetal growth and cancer biology.

3T3 Cells↗
PubMed1998

Insulin-stimulated cell growth in insulin receptor substrate-1-deficient ZR-75-1 cells is mediated by a phosphatidylinositol-3-kinase-independent pathway.

In many human breast cancers and cultured cell lines, insulin receptor expression is elevated, and insulin, via its own insulin receptor, can stimulate cell growth. It has recently been demonstrated that the enzyme phosphatidylinositol-3-kinase (PI3-K) mediates various aspects of insulin receptor signaling including cell growth. In order to understand the mechanisms for insulin-stimulated cell growth in human breast cancer, we measured insulin-stimulable PI3-K activity in a non-transformed breast epithelial cell line, MCF-10A, and in two malignantly transformed cell lines, ZR-75-1 and MDA-MB157. All three cell lines express comparable amounts of insulin receptors whose tyrosine autophosphorylation is increased by insulin, and in these cell lines insulin stimulates growth. In MDA-MB157 and MCF-10A cells, insulin stimulated PI3-K activity three- to fourfold. In ZR-75-1 cells, however, insulin did not stimulate PI3-K activity. In ZR-75-1 cells PI3-K protein was present, and its activity was stimulated by epidermal growth factor, suggesting that there might be a defect in insulin receptor signaling upstream of PI3-K and downstream of the insulin receptor. Next, we studied insulin receptor substrate-1 (IRS-1), a major endogenous substrate for the insulin receptor which, when tyrosine is phosphorylated by the insulin receptor, interacts with and activates PI3-K. In ZR-75-1 cells, there were reduced levels of protein for IRS-1. In these cells, both Shc tyrosine phosphorylation and mitogen-activated protein kinase (MAP-K) activity were increased by the insulin receptor (indicating that the p21ras pathway may account for insulin-stimulated cell growth in ZR-75-1 cells). The PI3-K inhibitor LY294002 (50 microM) reduced insulin-stimulated growth in MCF-10A and MDA-MB157 cell lines, whereas it did not modify insulin effect on ZR-75-1 cell growth. The MAP-K/Erk (MEK) inhibitor PD98059 (50 microM) consistently reduced insulin-dependent growth in all three cell lines. Taken together, these data suggest that in breast cancer cells insulin may stimulate cell growth via PI3-K-dependent or-independent pathways.

Breast Neoplasms↗
PubMed1997

Autosomal dominant polycystic kidney disease linked to PKD2 locus in a family with severe extrarenal manifestations.

We report a large three-generation autosomal dominant polycystic kidney disease family from Northern Italy found to be associated with the PKD2 locus. Hepatic involvement (liver cysts, fibrosis, cholelithiasis or jaundice), subarachnoidal hemorrhage (1 case) and esophageal diverticula (1 case) were present in affected individuals. Among the older members, the males (aged 54-61 years) had hepatic cysts or fibrosis and were on chronic hemodialysis, the females (aged 69 and 70 years) had hepatic cysts, hepatomegaly, mild fibrosis and a mild and moderate renal impairment, respectively. In this family, clinical findings do not differ substantially from those reported for PKD1.

Adolescent↗
PubMed1993

[Perinatal and maternal pathology in 38 pregnant women with endemic goiter].

In a group of 38 pregnant women with primary, uni- or multinodular non-toxic endemic goitre, who were clinically euthyroid, 7.8% (3 cases) had previously undergone strumectomy for benign pathologies of the goitre and 10.5% (4 cases) received L-thyroxine therapy during pregnancy at a dose of 50 or 100 micrograms/day; during the course of pregnancy goitre was asymptomatic in 37 women (97.4%) and an endocystic hemorrhage occurred in 1 (2.6%) case. The goitre increased in volume in 42.1% (16 cases) of pregnant women monitored to term. Out of 20 patients undergoing ELISA of hormonal levels, 6 (30%) revealed TSH concentration more than twice the maximum normal value with normal concentrations of other thyroid hormones. There was a significant inverse correlation (r = 0.525) between T4 and TSH. Birth at term occurred at 39.9 +/- 2.6 weeks and was spontaneous in 78.9% of cases (30 cases) and laparotomic in 21.1% (8 cases). Perinatal pathologies included: 1 case (2.6%) of endo-uterine fetal death, 1 case of oligoamnios and 1 of IUGR. Funicular pathologies were observed in 13.1% of patients (5 cases). The Apgar index was > 8 in the 37 live births. The mean weight of male and female neonates and neonates from nulliparas and pluriparas was within the norm. When the data examined were compared to the results of the control group it was seen that there were no statistically significant differences.

Adult↗
PubMed1990

[Sensitization to ethylene oxide: a possible cause of reactions in hemodialysis patients].

147 hemodialyzed patient were studied for the presence of allergic reactions related to the dialytic treatment. Total IgE and specific IgE to common inhalants, ethylene oxide and phthalic anhydride were determined in all patients. The same determinations were also performed in two control groups. Specific IgE to ethylene oxide were detected in 7 sera. Among these 6 had a high total IgE level and 2 had a positive Phadiatop. Only 3 among the 7 positive patients had adverse reactions related to the hemodialysis (one suffered from itching, one from urticaria and the third from angioedema and hypotension). The resolution of the symptoms was obtained utilizing a gamma-rays sterilized filter. Therefore ethylene oxide sensitization may be a cause of some problems during hemodialysis. We couldn't find a relationship between atopic status and sensitization to ethylene oxide in as much in only 2 out of 7 patients sensitized to ethylene oxide, specific IgE to common inhalants were detected.

Aged↗
PubMedDate not supplied

Insulin-stimulated glycogen synthesis in cultured hepatoma cells: differential effects of inhibitors of insulin signaling molecules.

In rat HTC hepatoma cells overexpressing human insulin receptors, insulin stimulated glycogen synthesis by 55-70%. To study postreceptor signaling events leading to insulin-stimulated glycogen synthesis in these cells, we have employed pathway-specific chemical inhibitors such as LY294002, rapamycin and PD98059 to inhibit phosphatidylinositol-3-kinase (PI3K), p70 ribosomal S6 kinase and mitogen-activated protein kinase (MAPK) kinase/MAPK, respectively. LY294002 (50 microM) completely abolished insulin-stimulated glycogen synthesis whereas rapamycin (2-20 nM) partially inhibited it. Neither LY294002 nor rapamycin significantly affected the basal glycogen synthesis. However, PD98059 (100 microM) significantly inhibited the basal glycogen synthesis without affecting insulin-stimulated glycogen synthesis. In these cells, insulin at 100 nM decreased glycogen synthase kinase 3 alpha (GSK3 alpha) activity by 30-35%. LY294002, but neither rapamycin nor PD98059, abolished insulin-induced inactivation of GSK3 alpha. These data suggest that insulin-stimulated glycogen synthesis in rat HTC hepatoma cells is mediated mainly by PI3K-dependent mechanism. In these cells, inactivation of GSK3 alpha, downstream of PI3K, may play a role in insulin-stimulated glycogen synthesis.

Amino Acid Sequence↗