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Y Oh

Publications and source records attributed to Y Oh.

At least 127 records · Page 7Linked to original sources
PubMed1994

Insulin-like growth factor binding protein-3 concentrations and insulin-like growth factor binding protein-3 protease activity in sera of patients with malignant solid tumors or leukemia.

IGF binding proteins (IGFBP) regulate the bioavailability and bioactivity of IGF. The major IGFBP in serum is IGFBP-3. We investigated whether sera from children with malignancies show alterations in levels of IGFBP-3 as measured by Western ligand blot analysis (WLB) and RIA with alpha IGFBP-3gl, a specific rabbit polyclonal antibody. Furthermore, IGFBP-3 proteolysis was quantified by densitometric analysis of [125I]IGFBP-3 protease assays, and IGFBP-3 fragments were visualized by Western immunoblot with alpha IGFBP-3gl. We examined sera from 21 children with solid tumors, five patients with sarcoma who had reached complete remission, and 13 children with acute leukemia. Serum samples were collected at diagnosis, before initiation of therapy. Sera of 10 healthy children served as normal controls. Children with solid tumor or leukemia had significantly higher (p < 0.001) IGFBP-3 protease activity in serum than did normal controls or patients with sarcoma in complete remission. Corresponding to this finding, densitometry of WLB showed lower IGFBP-3 levels in sera of children with malignancies in comparison with normal controls. The negative correlation (p < 0.001, r = -0.80) between IGFBP-3 proteolysis, as measured by [125I]IGFBP-3 protease assay, and IGFBP-3 band density on WLB indicates that proteolysis is the probable reason for reduction of IGFBP-3 on WLB. IGFBP-3 concentrations measured by RIA were in the normal range for most patients, further indicating that differences in serum IGFBP-3 levels measured by WLB reflect protease activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

Insulin-like growth factor-binding protein-2 concentrations in cerebrospinal fluid and serum of children with malignant solid tumors or acute leukemia.

Many tumor cell lines express insulin-like growth factors (IGFs) as autocrine growth factors and IGF-binding protein-2 (IGFBP-2) as a major IGFBP, which, in turn, regulates the bioavailability and bioactivity of IGFs. The aim of our study was to investigate 1) whether children with malignancies have elevated IGFBP-2 levels in cerebrospinal fluid (CSF) and serum, and 2) whether IGFBP-2 levels in these biological fluids could be useful markers for the diagnosis and follow-up of certain tumor types. We, therefore, measured IGFBP-2 levels in the CSF and serum of children with malignancies by Western ligand blot analysis; RIA with alpha IGFBP-2, a polyclonal antibody for human IGFBP-2; and immunoprecipitation with alpha IGFBP-2 and alpha Hec-1a, a polyclonal antibody that recognizes IGFBP-2 and -3. Furthermore, the expression of IGFBP-2 messenger ribonucleic acid in tumor tissue from three central nervous system (CNS) tumor patients was analyzed by Northern blot analysis. We examined CSF from 21 children with malignant CNS tumors, 25 patients with acute leukemia, and 4 patients with peripheral solid tumors and compared the IGFBP-2 levels with those in CSF from 21 patients who received a lumbar puncture to exclude meningitis. Serum was obtained from 7 patients with solid tumor, 12 patients with malignant CNS tumor, and 16 patients with acute leukemia. The serum IGFBP-2 levels were compared to serum levels in 5 patients with sarcoma who had reached complete remission and 13 normal control children. CSF and serum were collected at the same time, before initiation of therapy. Patients with malignant CNS tumors showed elevated IGFBP-2 levels in CSF (P < 0.001), whereas patients with solid peripheral tumor or acute leukemia had normal IGFBP-2 levels in CSF. CNS tumor patients with microscopically detectable malignant cells in the CSF had the highest CSF IGFBP-2 levels. Serum IGFBP-2 levels were increased in patients with solid peripheral tumors (P < 0.05), whereas patients in complete remission had normal serum IGFBP-2 levels. In summary, IGFBP-2 was elevated specifically in CSF from patients with CNS tumor, whereas IGFBP-2 serum levels were elevated in children with various peripheral tumors. We conclude that IGFBP-2 in CSF could be a specific marker for malignant CNS tumors. We detected high IGFBP-2 messenger ribonucleic acid expression in 1 of 3 CNS tumor tissues analyzed.

Adolescent↗
PubMed1994

Identification of insulin-like growth factor-binding protein-3 (IGFBP-3) fragments and IGFBP-5 proteolytic activity in human seminal plasma: a comparison of normal and vasectomized patients.

Previous studies have demonstrated that insulin-like growth factor (IGF) peptides, IGF-binding proteins (IGFBPs), and IGFBP-3 proteolytic activity, are present in human seminal plasma (SP). In this study, we have further characterized the IGFBPs in SP using immunoprecipitation and Western ligand blotting, Western immunoblotting, affinity cross-linking and immunoprecipitation, and RIA of IGFBP-3 using two different assays and have identified additional proteolytic activities for IGFBP-4 and IGFBP-5 in SP. Immunoprecipitation with antibodies to IGFBP-2, IGFBP-3, and IGFBP-4, before and after affinity cross-linking, demonstrated that intact IGFBP-2 and IGFBP-4 are present in SP, but intact IGFBP-3 is absent. Low mol wt fragments of IGFBP-3, which did not bind to IGF-I or IGF-II on Western ligand blot and did not cross-link to IGF-II, were demonstrated on Western immunoblot and were measurable by two different RIAs. Proteolytic activities for IGFBP-4 and IGFBP-5 were demonstrated in SP by incubation with the respective iodinated IGFBPs. On comparing the proteolytic activity for IGFBP-4 by purified prostate-specific antigen (PSA; a known IGFBP-3 protease in SP) or by SP with measured equivalent concentrations of PSA, the dose response and fragment patterns were identical. With IGFBP-5, however, proteolysis by purified PSA was different from that by SP with measured equivalent concentrations of PSA: 1) proteolysis by pure PSA was less efficient than matched concentrations of SP; 2) the pattern of fragments after proteolysis by pure PSA was different from that after proteolysis by matched concentrations of SP; and 3) proteolysis by purified PSA was significantly inhibited by phenylmethylsulfonylfluoride and aprotinin, but proteolysis by SP was not. We conclude that human SP contains intact IGFBP-2 and IGFBP-4, but has only IGFBP-3 fragments with low affinity for IGF peptides; that PSA is able to proteolyze IGFBP-4 and IGFBP-5 (as well as IGFBP-3); and that an additional IGFBP-5 protease is probably present in SP. There was no significant difference in any of these findings in SP from normal volunteers, vasectomized patients, or patients with idiopathic azoospermia. The roles of IGFBPs and IGFBP proteases in the male reproductive system and male infertility remain to be further elucidated.

Blotting, Western↗
PubMed1994

Alteration in insulin-like growth factor-binding proteins (IGFBPs) and IGFBP-3 protease activity in serum and urine from acute and chronic renal failure.

The insulin-like growth factors, IGF-I and IGF-II, are proteins that promote cellular growth and differentiation of various organs, including the kidney. These peptides interact with high affinity cell surface receptors and bind to a family of IGF-binding proteins (IGFBPs). Altered serum and urinary IGFBP patterns in children with chronic renal failure have been previously described. In this study, we evaluated serum and urinary IGFBP profiles in acute renal failure patients (ARF; n = 10) and chronic renal failure patients (n = 10), using Western ligand blots. Most patients with acute or chronic renal failure showed decreased intact serum IGFBP-3 and increased serum IGFBP-2. Both groups displayed marked urinary IGFBP alterations, including increased urinary IGFBP-1 and totally absent urinary IGFBP-3, as detected by Western ligand blot. To evaluate altered IGFBP profiles, we performed IGFBP-3 protease assays with sera and urine from renal failure patients and normal controls. Although control urine had only minor protease activity (defined by the ability to degrade [125I]IGFBP-3), significant protease activity was found in urine from renal failure patients. The proteolytic pattern and susceptibility to protease inhibitors in most renal failure urine samples were the same as those seen in normal urine and with plasmin. Protease activity was completely inhibited by serine protease inhibitors. We speculate that urinary protease activity is mediated primarily by a serine protease(s), which may be involved in the modulation of renal IGF activity in health and disease.

Acute Kidney Injury↗
PubMed1994

An important role of glomerular segmental lesions on progression of IgA nephropathy: a multivariate analysis.

The independent predictors of progression of IgA nephropathy (IgAN) were investigated by multivariate life table analysis, using Cox's proportional hazard model, in 225 patients with IgAN diagnosed by renal biopsy (Bx). There were 105 men and 120 women. Mean age at Bx was 32.5 years. The follow-up period following Bx was 4.0 +/- 2.6 yrs, ranging from 5 months to 11 yrs. The clinical parameters analyzed were age at the time of discovery of the disease, age at Bx, intervals from discovery to Bx, presence or absence of macrohematuria, and clinical data at Bx such as presence or absence of hypertension, the degree of hematuria, the amount of urinary protein excretion, serum creatinine and serum IgA concentration. The following immunopathological parameters were also examined; glomerular hypercellularity index, percentage of glomeruli associated with segmental lesions such as tuft adhesions, crescents and segmental sclerosis, percentage of obliterated glomeruli by global sclerosis, severity of interstitial infiltration, fibrosis, arterial wall thickening, arterial hyaline changes, and intensity of the depositions of IgG, IgA, IgM, C3, C1q and fibrinogen by immunofluorescent study. Among all clinical and pathologic parameters examined, the following parameters were proved to be significant independent predictors of progression of IgAN: serum creatinine exceeding 1.5 mg/dl in men and 1.3 mg/dl in women, proteinuria over 2 g/day, segmental lesions involving more than 25% of glomeruli and interstitial fibrosis occupying more than 25% of cortical area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Clinicopathological study of poststreptococcal glomerulonephritis in the elderly.

In order to characterize the clinical features in elderly patients with poststreptococcal glomerulonephritis (PSGN), 31 patients, who were both histologically and immunologically proven to be PSGN, were divided up into 3 groups according to age; elderly patients being 55 years or older (n = 7), middle-aged patients being 40 to 54 years old (n = 7) and younger patients being 20 to 39 years old (n = 17). Renal functional impairment as indicated by serum creatinine levels of over 2.0 mg/dl, developed in 4 of the elderly patients and later completely improved at the end of the follow-up period (178.9 +/- 150.7 days). On the other hand, none of the middle-aged and younger patients revealed any renal function impairment. Hypertension was observed more frequently in elderly patients than in younger patients, and was 86% and 6% at the time of admission, respectively. In addition, 43% of elderly patients remained hypertensive at the time of discharge. There was no difference in total protein, ASO, CH50, the degree of proteinuria or proliferative and exudative features in renal histology among the three groups. None of the elderly patients with PSGN died or developed persistent renal failure. In conclusion, elderly patients with PSGN had a high incidence of renal functional impairment and hypertension compared to the younger patients on admission, however, their short-term prognosis seems to be favorable.

Adult↗
PubMed1993

Demonstration of receptors for insulin-like growth factor binding protein-3 on Hs578T human breast cancer cells.

Hs578T human breast cancer cells are from an estrogen receptor-negative breast cell line derived from a highly aggressive mammary tumor. Our previous insulin-like growth factor binding protein-3 (IGFBP-3) binding studies (Oh, Y., Müller, H. L., Lamson, G., and Rosenfeld, R. G. (1993) J. Biol. Chem. 268, 14964-14971) have demonstrated specific binding of IGFBP-3 on the Hs578T cell surface and a significant inhibitory effect of IGFBP-3, itself, on monolayer growth. In this study, we have demonstrated cell surface association proteins that are specific for IGFBP-3 by showing: 1) detection of 20-, 26-, and 50-kDa proteins by affinity cross-linking with 125I-IGFBP-3E. coli and immunoprecipitation of cell monolayers and cell lysates with anti-IGFBP-3 antibodies; 2) dose-dependent competition of 125I-IGFBP-3E. coli by unlabeled IGFBP-3E. coli; 3) inhibition of IGFBP-3 binding to these cell surface proteins by EDTA and by coincubation with native insulin-like growth factor II (IGF-II), but not by coincubation with [Gln6,Ala7,Tyr18,Leu19,Leu27]IGF-II, an IGF-II analog with decreased affinity for IGFBP-3; and 4) partial purification of 20- and 26-kDa species by IGFBP-3.anti-IGFBP-3 antibody immunoaffinity membranes. Characteristics of these specific IGFBP-3 cell surface association proteins are identical to those observed in our previous monolayer binding assay and monolayer growth assay experiments. The specificity of binding and the inhibitory effect of IGFBP-3 binding on Hs578T cell growth suggest that these cell surface proteins are IGFBP-3-specific receptors or receptor subunits mediating the direct inhibitory effect of IGFBP-3 on monolayer growth of Hs578T cells.

Amino Acid Sequence↗
PubMed1993

Insulin-like growth factor (IGF)-independent action of IGF-binding protein-3 in Hs578T human breast cancer cells. Cell surface binding and growth inhibition.

Estrogen receptor-negative Hs578T human breast cancer cells secrete insulin-like growth factor binding protein (IGFBP)-3 and IGFBP-4 as major binding protein (BP) species. Our previous immunohistochemical studies (Oh, Y., Müller, H. L., Pham, H., Lamson, G., and Rosenfeld, R. G. (1992) Endocrinology 131, 3123-3125) have demonstrated the existence of cell surface-associated IGFBP-3 and release of cell surface-associated IGFBP-3 into conditioned media by addition of IGF peptide in Hs578T cells. In this study, we have demonstrated that IGFBP-3 binding on the cell surface is specific and receptor-mediated, by showing: 1) a dose-dependent increase of IGFBP-3 binding by addition of divalent cations (CaCl2 and MnCl2); 2) dose-dependent competition of 125I-IGFBP-3E. coli by unlabeled IGFBP-3E.coli (> 80% competition at 100 nM), but not by IGFBP-1 or fibronectin. In addition, exogenous IGFBP-3 treatment resulted in a significant inhibitory effect on monolayer growth of Hs578T cells. This inhibitory effect of IGFBP-3 was shown to be specific and IGF-independent by demonstrating: 1) dose-dependent inhibition on cell growth (60% inhibition at 20 nM) and inhibition on DNA synthesis (10 nM; p < 0.05, 20 nM; p < 0.005) by exogenous IGFBP-3E. coli, but not by IGFBP-1; 2) absence of stimulatory effects on monolayer cell growth by either native IGFs or IGF analogs which have significantly decreased affinity for IGFBPs, but retain full affinity for type 1 and 2 IGF receptors; 3) significant diminution of the IGFBP-3 inhibitory effects on monolayer growth by coincubation with native IGFs, but not by coincubation with IGF analogs with decreased affinity for IGFBP-3. In conclusion, exogenous IGFBP-3 shows specific binding on the cell surface and can inhibit Hs578T cell monolayer growth by itself, suggesting the existence of specific membrane-associated proteins or receptors for IGFBP-3. Furthermore, IGF-I and -II can attenuate inhibitory effect of IGFBP-3 by forming IGF.IGFBP-3 complexes, thereby preventing cell surface binding of IGFBP-3.

Amino Acid Sequence↗
PubMed1993

Rapid purification of an amiloride-sensitive Na+ channel from bovine kidney and its functional reconstitution.

We have used ion-exchange chromatography to isolate and partially purify an amiloride-sensitive Na+ channel protein from bovine renal papillae. The channel was purified by sequential chromatography on an anion-exchange and a cation-exchange cartridge. Five different approaches were applied to monitor the degree of purification of this Na+ channel. First, [3H]Br-benzamil binding activities to the purified proteins were determined. We found that no specific binding was measured in protein fractions eluted from a QUAT anion-exchange cartridge, whereas proteins eluted from an SP cation-exchange cartridge bound [3H]Br-benzamil specifically. Second, we examined the HPLC profiles of purified proteins through both ion-exchange chromatography steps and observed a major peak of very high molecular mass proteins (> 670 kDa) after final purification. Third, using anti-Na+ channel antibodies, Western and slot blot analyses were performed to assess qualitatively the enrichment of channel epitopes at each step of purification. Fourth, amiloride-sensitive 22Na+ influx could be demonstrated after the proteins eluted from the cation-exchange resin were reconstituted into liposomes. Fifth, the proteins eluted from the cation-exchange resin were reconstituted into planar lipid bilayers, and single amiloride-sensitive Na+ channel activity was measured. In summary, we have developed a new protocol applicable for speed- and scale-up purification of a functional amiloride-sensitive Na+ channel from bovine kidney papillae.

Amiloride↗
PubMed1993

Single-channel characteristics of a purified bovine renal amiloride-sensitive Na+ channel in planar lipid bilayers.

We have purified an amiloride-inhibitable Na+ channel protein from bovine renal papillae using ion-exchange and immunoaffinity chromatography. In the present study, these purified Na+ channels were reconstituted into planar lipid bilayers, and their single-channel characteristics were studied. We observed both large- and small-conductance Na(+)-selective ion channels in planar lipid bilayers. Single-channel conductance for the large- and small-conductance channels saturated as a function of Na+ concentration. These relations could be fitted by a simple Langmuir isotherm with a Michaelis constant of 55 and 45 mM and a maximum open-state conductance of 56 or 8.4 pS, respectively. Both channels were perfectly cation selective, with a Na(+)-to-K+ permeability ratio of 6.7:1 for the large channel and 7.8:1 for the small channel, and their open single-channel current-voltage relations were linear when bathed with symmetrical Na+ solutions. The percent open time of the reconstituted large or small channels varied between 10 and 50% or 1 and 20%, respectively. After application of amiloride, both the large- and small-conductance Na+ channels were inhibited in a dose-dependent manner.

Amiloride↗
PubMed1993

Regulation by phosphorylation of purified epithelial Na+ channels in planar lipid bilayers.

To determine the mechanism by which vasopressin increases apical membrane Na+ entry, we evaluated whether or not this hormone could recruit Na+ channels from a subapical membrane pool using specific polyclonal antibodies raised against high amiloride affinity bovine renal papillary Na+ channels. We also studied the effect of protein kinase A (PKA)-mediated phosphorylation on single-channel activity of highly purified Na+ channels incorporated into planar lipid bilayer membranes. PKA induced a significant increase in open-channel probability (Po) with no change in single-channel conductance. As shown previously and reconfirmed in the present work, PKA catalyzed the phosphorylation of a single subunit of this Na+ channel protein, namely, a 300-kDa polypeptide. On the other hand, protein kinase C, in combination with diacylglycerol, Ca2+, and phosphatidylserine, phosphorylated both the 130- and 55-kDa subunits of this purified Na+ channel, with a concomitant decrease in Po of both untreated and previously PKA-treated channels. We also found, in expression studies conducted in confluent monolayers of amphibian renal A6 cells, that vasopressin did not induce the apical insertion of new channel proteins. These observations support the hypothesis that vasopressin increases the apical Na+ permeability by activating Na+ channels already resident in the apical membrane by a direct phosphorylation mechanism rather than by cytoplasmic recruitment of latent Na+ channels.

Animals↗
PubMed1993

Culture-induced alterations in alveolar type II cell Na+ conductance.

Changes in Na+ transport in rat alveolar type II (ATII) cells during culture were quantified and related to alterations in spatial distribution of proteins antigenically related to amiloride-sensitive Na+ channels. Adult rat ATII cells were cultured for periods ranging from 24 to 96 h. When patch clamped in the whole cell mode, both freshly isolated and cultured ATII cells exhibited outwardly rectified Na+ currents. At 0 and 24 h in culture, these currents were equally inhibited by amiloride, benzamil, and 5-(N-ethyl-N-isopropyl)-2',4'-amiloride (inhibitory constant approximately 1 microM). These conductive pathways were equally permeable to Na+ and K+. Immunocytochemical localization at 0 or 24 h in culture revealed the presence of plasma membrane antigenic sites; after 48 h, the appearance of intracellular antigenic sites increased significantly. A single band of molecular mass 135 kDa in membrane proteins of freshly isolated ATII cells was recognized in Western blots; at 48 h in culture, two lower bands with molecular masses of 75 and 65 kDa were detected in either membrane or cytoplasmic proteins. Photolabeling with 2'-methoxy-5'-nitrobenzamil showed that the 135-, 75-, and 65-kDa bands contained amiloride-binding sites. These results suggest the presence of low amiloride affinity conductive pathways in freshly isolated and cultured ATII cells. Culturing ATII cells resulted in internalization and possible breakdown of these pathways and decreased Na+ transport.

Amiloride↗
PubMed1993

Characterization of the affinities of insulin-like growth factor (IGF)-binding proteins 1-4 for IGF-I, IGF-II, IGF-I/insulin hybrid, and IGF-I analogs.

Insulin-like growth factor (IGF)-binding proteins (BPs) bind IGF-I and IGF-II with high affinity and modify the activity of IGF peptides in a complex manner. We have characterized the affinities of IGFBP-1-4 for IGF-I and -II by employing 1) purified IGFBP preparations, 2) both [125I]IGF-I and [125I]IGF-II as radioligands, and 3) multiple IGF analogs designed to have altered affinities for IGFBPs. To this end, human (h) IGFBP-1, hIGFBP-2, and rat (r) IGFBP-4 have been purified to homogeneity from human amniotic fluid, human prostate epithelial cell culture, and B104 rat neuroblastoma cells; for human IGFBP-3, the glycosylated recombinant form (rec-hIGFBP-3), produced in Chinese hamster ovary cells, was employed. The IC50 values of IGF-I for hIGFBP-1, hIGFBP-2, rec-hIGFBP-3, rIGFBP-4, and human serum IGFBPs were 0.05 +/- 0.01, 5.0 +/- 0.01, 0.25 +/- 0.20, 0.6 +/- 0.4, and 0.1 +/- 0.01 ng/ml, respectively. While hIGFBP-1 and rIGFBP-4 had virtually equivalent affinities for IGF-I and IGF-II, hIGFBP-2 and rec-hIGFBP-3 demonstrated 2- to 5-fold higher affinities for IGF-II than for IGF-I. Studies with [Gln3,Ala4,Tyr15,Leu16]IGF-I and Des-(1-3)-IGF-I indicate that specific residues in the first 16 amino acids of the B domain of IGF-I appear to be critical for binding to all of the IGFBPs tested, but not to IGF receptors. However, severe modifications in the B domain disrupt binding affinity, not only for IGFBPs, but also for receptors (IGF-I/insulin hybrid and B-chain mutant). Interestingly, modifications in the A domain of IGF-I, which is believed to contain residues critical for binding to IGF-I and insulin receptors, show differential effects on binding affinity to BPs. [Thr49,Ser50,Ile51]IGF-I, which has normal affinity for the type I IGF receptor, shows at least a 500-fold decreased affinity for hIGFBP-1 and recombinant hIGFBP-3, in contrast to 50- to 100-fold reduced affinity for hIGFBP-2 and rIGFBP-4, and 5- to 10-fold reduced affinity for purified human serum IGFBP-3. More significantly, [1-27,Gly4,38-70]IGF-I shows a 30-fold decreased affinity for the type I IGF receptor and 10- and 2.5-fold reduced affinities for hIGFBP-1 and rec-hIGFBP-3, respectively, but no reduction in affinity for hIGFBP-2 or rIGFBP-4.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

Concentrations of insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3), IGF, and IGFBP-3 protease activity in cerebrospinal fluid of children with leukemia, central nervous system tumor, or meningitis.

Insulin-like growth factor-II (IGF-II) is the major IGF in human cerebrospinal fluid (CSF), whereas IGF-I is only detectable in trace amounts. The major IGFBPs in CSF are IGFBP-2 and IGFBP-4. Normally, IGFBP-3 is a minor component in CSF of healthy subjects, but may be increased in pathological states. We investigated IGF-I, IGF-II, and IGFBP-3 levels by specific RIAs in CSF from patients with central nervous system (CNS) tumor or leukemia and compared them with values in patients with meningitis. Further, as proteolysis of IGFBP-3 is part of the modulation of IGF activity, IGFBP-3 fragmentation was quantified by densitometric analysis of [125I]IGFBP-3 protease assays. We examined CSFs of 23 children with malignant CNS tumors, 18 children with leukemia, and 13 children with meningitis. The CSF from 38 children who received lumbar punctures to exclude meningitis was used to define the normal range for IGF-I, IGF-II, IGFBP-3, and IGFBP-3 protease activity in CSF. CNS tumor and leukemia patients had normal levels of IGF-I and IGF-II in CSF, whereas the IGF-II concentration in CSF of meningitis patients was elevated (P < 0.0001). Only 2 of 13 (15%) meningitis patients had elevation of CSF IGFBP-3 concentrations, despite high numbers of inflammatory cells. By comparison, elevated IGFBP-3 concentrations were found in the CSF of 16 of 23 (70%) CNS tumor patients and 6 of 7 (86%) CNS tumor patients with microscopically detectable malignant cells in CSF. Twelve of 13 (92%) patients with medulloblastoma or ependymoma and all 7 medulloblastoma/ependymoma patients with malignant cells in CSF had elevated IGFBP-3 concentrations. The IGFBP-3 protease activity in CSF was elevated in 15 of 16 (94%) patients with CNS tumors of high grade histological malignancy. Five of 6 patients (83%) with acute leukemia and microscopically detectable malignant cells in CSF at the time of diagnosis showed elevated IGFBP-3 concentrations, with normalization after chemotherapy. Leukemia patients without malignant cells in CSF had normal IGFBP-3 concentrations. We conclude that in CSF of children with highly malignant CNS tumor or CNS leukemia, IGFBP-3 is elevated. This phenomenon could be caused by disruption of the blood-CSF barrier and entry of IGFBP-3 from serum, although this appears unlikely, especially for CNS leukemia. More likely possibilities are 1) local production of IGFBP-3 by CNS tumor tissue and secretion into the CSF, or 2) local production of IGFBP-3 by malignant cells within the CSF.

Adolescent↗
PubMed1993

Insulin-like growth factor binding protein (IGFBP)-3 levels in conditioned media of Hs578T human breast cancer cells are post-transcriptionally regulated.

Hs578T human breast cancer cells secrete insulin-like growth factor binding protein (IGFBP)-3 (41-kDa and 39-kDa) and IGFBP-4 (24-kDa) as major BP species. In addition, cell surface-associated IGFBP-3 is demonstrable by use of cell monolayer affinity cross-linking or by employing immunoperoxidase staining of the cell surface with specific polyclonal anti-human IGFBP-3 antibodies (alpha IGFBP-3gl and alpha IGFBP-3ngl). In this study, we have demonstrated that regulation of Hs578T IGFBP-3 by IGF peptides is specific, non-receptor mediated, and post-translational by showing: 1) dose-dependent increase of IGFBP-3 in conditioned media(CM) following addition of IGF-I and IGF-II (maximum 8-13-fold increase at 100 ng/ml concentration), but not by insulin up to 1 microgram/ml; 2) confirmation of IGF-induced increases in CM concentrations of IGFBP-3 by means of Western ligand blot, affinity cross-linking, and IGFBP-3-specific radioimmunoassay; 3) increase of IGFBP-3 in CM by addition of IGF analogs which retain full affinity for IGFBPs ([Leu27]IGF-II and [Tyr55,Gln56]IGF-I), but not by IGF analogs which have significantly decreased affinity for IGFBPs ([Gln3,Ala4,Tyr15,Leu16]IGF-I, [Gln6,Ala7,Tyr18,Leu19,Leu27]IGF-II and IGF-I/insulin hybrid); 4) no change in IGFBP-3 mRNA following addition of IGFs; 5) existence of metal ion-dependent IGFBP-3 specific protease in CM and protection of IGFBP-3 from protease by formation of [IGF:IGFBP-3] complexes; and 6) release of cell surface-associated IGFBP-3 into CM by addition of IGF peptides. These studies demonstrate that IGF peptides regulate CM concentrations of IGFBP-3 through non-receptor mediated events, including dissociation of cell surface-associated IGFBP-3 and protection of IGFBP-3 from protease activity.

Blotting, Northern↗