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Biomedical subjects

S Mohan

Publications and source records attributed to S Mohan.

At least 127 records · Page 7Linked to original sources
PubMed1997

Structural and functional analysis of the 5'-flanking region of the human insulin-like growth factor binding protein (IGFBP)-4 gene.

More than 3 kb of the human (h)IGFBP-4 gene 5'-flanking region was sequenced and assessed for promoter activity. The hIGFBP-4 promoter resides within a CpG island and demonstrates strong basal activity in human osteoblast-like osteosarcoma and COS-7 monkey kidney cells. Transient transfection of cells with hIGFBP-4 promoter-linked deletion constructs demonstrated that multiple cooperating cis-acting elements within 836 bp of the 5'-flanking region contributed to overall promoter strength.

Animals↗
PubMed1997

Effects of inhibitors of signal transduction pathways on transforming growth factor beta1 and osteogenic protein-1-induced insulinlike growth factor binding protein-3 expression in human bone cells.

Signal transduction initiated by TGFbeta1 and OP-1 was studied in MG63 human osteosarcoma cells and in normal human bone cells (HBCs) in the presence of inhibitors of signal transduction events, using insulinlike growth factor binding protein-3 (IGFBP-3) production as an end point. Treatment of serum-free MG63 cells and normal HBCs with TGFbeta1 increased IGFBP-3 protein level several fold in the conditioned medium. This effect of TGFbeta1 was mediated by increased de novo synthesis because mRNA level increased to the same extent as protein level and TGFbeta1 treatment had very little effect on IGFBP-3 protease activity. The stimulatory effect of TGFbeta1 on IGFBP-3 production was inhibited in a dose-dependent manner by pretreatment with staurosporine, a protein kinase C inhibitor, or with vanadate, a phosphotyrosyl protein phosphatase inhibitor in both MG63 cells and normal HBCs. In addition, pretreatment with okadoic acid, an inhibitor of serine/threonine protein phosphatase, counteracted TGFbeta1 induction of IGFBP-3 production. Interestingly, pretreatment of MG63 cells or HBCs with staurosporine, vanadate, or okadoic acid augmented OP-1 stimulation of IGFBP3 production. Staurosporine- or vanadate-induced changes in IGFBP-3 protein levels in the presence of TGFbeta1 and OP-1 were associated with corresponding changes in IGFBP-3 mRNA levels in MG63 cells. These findings are consistent with the hypothesis that TGFbeta1 and OP-1 increase IGFBP-3 expression via distinct intracellular signal transduction pathways.

Bone Morphogenetic Protein 7↗
PubMed1997

Serum insulin-like growth factor binding protein (IGFBP)-4 and IGFBP-5 levels in aging and age-associated diseases.

Because impaired bone formation is a major contributor to the pathogenesis of senile (type II) osteoporosis, and because insulin-like growth factors (IGFs) have been shown to be important stimulators of bone formation in vitro and in vivo, studies have been focused towards clarifying the role of IGF system in the age-related impairment in bone formation. To evaluate if changes in circulating and bone cell production of IGF binding protein (IGFBP)-4 and IGFBP-5 could contribute to age-related impairment in bone formation, the authors measured serum and skeletal levels of IGFBP-5, and serum levels of IGFBP-4 during aging. Circulating levels of IGFBP-4 increased with age, whereas that of IGFBP-5 declined with age. Serum IGFBP-4 and IGFBP-5 levels showed significant positive correlations with serum levels of parathyroid hormone (PTH) and IGFs, respectively. In addition, skeletal content of IGFBP-5 declined with age. The age-related changes in IGFBP-4 and IGFBP-5 production could contribute, in part, to the decrease in osteoblast cell proliferation and deficiency in bone formation.

Adult↗
PubMed1997

Osteogenic protein-1 stimulates mRNA levels of BMP-6 and decreases mRNA levels of BMP-2 and -4 in human osteosarcoma cells.

Bone morphogenetic proteins (BMPs) are novel growth and differentiation factors that act on mesenchymal stem cells to initiate new bone formation in vivo and promote the growth and differentiation of cells in the osteoblastic lineage. In the present study, we examined the effects of recombinant human osteogenic protein-1 (also known as BMP-7) on the expression of related members of the BMP family using SaOS-2 and U2-OS, two human osteosarcoma cell strains. Evaluation of BMP-2, -4, and -6 mRNA expression indicates that OP-1 stimulated the mRNA levels of BMP-6 in both SaOS-2 cells (threefold) and U2-OS cells (fivefold) after 24 hours of treatment, while decreasing the mRNA levels of BMP-4 in SaOS-2 cells (80%) and BMP-2 and BMP-4 in U2-OS cells by 50% and 72%, respectively. BMP-2 mRNA expression, as examined by Northern blot analysis, was below detectable limits in SaOS-2 cultures. These results demonstrate that OP-1 modulates the mRNA expression of related members of the BMP family, suggesting a possible mode of action of OP-1 on the growth and differentiation of cells in the osteoblastic lineage in vitro.

Blotting, Northern↗
PubMed1997

Insulin-like growth factor binding protein production in bovine retinal endothelial cells.

Retinopathy is the most frequent microangiopathic complication in diabetes. Many circulating hormones and locally produced mitogenic factors have been involved. Bovine retinal endothelial cells (BRECs) were cultured to investigate if insulin, insulin-like growth factors (IGFs), IGF binding proteins (IGFBPs), and a chronic high-glucose condition could control endothelial cell growth. Specific IGF-I receptors with two binding sites with high (Kd 0.03 nmol/L) and low (Kd 1.3 nmol/L) affinity were found when analyzing families of displacement curves between IGF-I versus IGF-I and IGF-I versus insulin. However, IGFs failed to be mitogenic factors in these cells. This could be explained by an inhibitory effect due to the presence of specific IGFBPs with a molecular weight between 24 and 43 kd. Using Western blot and immunoblot analysis, Northern blot study, and specific radioimmunoassay (RIA), these IGFBPs have been identified as IGFBP-3, -2, -5, and -4. Insulin, which does not bind to IGFBPs, was a potent mitogenic factor in these cells at a high concentration (10 nmol/L), suggesting a cross-reaction to IGF-I receptor. These IGFBPs, except the 24-kd form (IGFBP-4), were modulated by both IGF-I and IGF-II, with a maximum effect at 100 and 10 nmol/L, respectively. This regulation on IGFBPs was IGF-I receptor-independent. In fact, (1) IGFBP mRNA levels were not modified after stimulation with 100 nmol/L IGF-I, (2) 100 nmol/L IGF plus an equimolar concentration of alpha IR3 did not affect IGFBP production, (3) Des(1-3)IGF-I had no effect on IGFBP modulation, whereas at 10 nmol/L it enhanced BREC thymidine cell incorporation, and (4) 100 nmol/L insulin, which at this concentration can cross-react with the IGF-I receptor, did not modify the IGFBP pattern. Chronic exposure (4 weeks) of BRECs to 25 mmol/L glucose had no effect on cell growth. However, after 3 weeks, we observed a decreased IGFBP detection, and addition of 100 nmol/L IGF-I did not change IGFBP levels and did not modify cell growth. Conversely, BRECs grown in regular medium for 4 weeks showed increased IGFBP production. In conclusion, we showed that conditions mimicking hyperinsulinemia, rather than high levels of IGFs, could regulate BREC growth and that the IGF-I analog, Des(1-3), even with reduced affinity for IGFBPs but in part capable of binding to IGFBP-3, significantly stimulated BRECs growth only at 10 nmol/L. IGF actions are modulated by locally produced endothelial IGFBPs, and in turn, these endothelial IGFBPs are regulated, via in IGF-I receptor-independent mechanism, by the presence of IGFs. The autoregulatory IGF system together with the direct glucose modulation of IGFBPs could contribute in diabetic subjects to the retinal endothelial cell growth and metabolism through local changes in IGF bioavailability.

Animals↗
PubMed1997

Circulating and skeletal insulin-like growth factor-I (IGF-I) concentrations in two inbred strains of mice with different bone mineral densities.

Recent work has demonstrated differences in femoral bone mineral density between two common inbred strains of mice, C3H/HeJ (C3H) and C57BL/6J (B6), across a wide age range. To investigate one possible mechanism that could affect acquisition and maintenance of bone mass in mice, we studied circulatory and skeletal insulin-like growth factor-I (IGF-I) and femoral bone mineral density (F-BMD) by pQCT in C3H and B6 progenitor strains, as well as serum IGF-I obtained from matings between these two strains and mice bred from subsequent F1 intercrosses (F2). Serum IGF-I measured by radioimmunoassay was more than 35% higher in virgin progenitor C3H than virgin B6 at 1, 4, 8, and 10 months of age, and in 8-month-old C3H compared with B6 retired breeders (p < 0.001). In the progenitors, there was also a strong correlation between serum IGF-I and serum alkaline phosphatase (r = 0.51, p = 0.001). In the 4 month F1 females IGF-I levels and F-BMD were intermediate between C3H and B6 progenitors. In contrast, groups of F2 mice with the highest or lowest BMD also had the highest or lowest serum IGF-I (p = 0.0001). IGF-I accounted for > 35% of the variance in F-BMD among the F2 mice. Conditioned media from newborn C3H calvarial cultures had higher concentrations of IGF-I than media from B6 cultures, and cell layer extracts from C3H calvariae exhibited greater alkaline phosphatase activity than cultures from B6 calvarial cells (p < 0.0001). The skeletal content of IGF-I in C3H tibiae, femorae, and calvariae (6-14 weeks of age) was also significantly higher than IGF-I content in the same bones of the B6 mice (p < 0.05). These data suggest that a possible mechanism for the difference in acquisition and maintenance of bone mass between these two inbred strains is related to systemic and skeletal IGF-I synthesis.

Aging↗
PubMed1997

Differential activation of NF-kappa B in human aortic endothelial cells conditioned to specific flow environments.

Endothelial cell-monocyte interaction plays an important role in atherogenesis. The expressions of some endothelial cell adhesion molecules involved in endothelial cell-monocyte interactions are regulated by transcription factor NF-kappa B. Because low shear stress has been known to influence endothelial monocyte adhesion, the differential activation of NF-kappa B under different flow regimens across time (0.5-24 h) was investigated. Nuclear proteins from flow-conditioned human aortic endothelial cells (HAEC) were analyzed by electrophoretic mobility shift assay using [gamma-32P]dATP-labeled NF-kappa B-specific oligonucleotide. Our results demonstrated that NF-kappa B activation was significantly elevated in HAEC exposed to prolonged (> 2 h) steady low shear (2 dyn/cm2) and pulsatile low shear (2 +/- 2 dyn/cm2) compared with HAEC exposed to high shear (16 dyn/cm2). In contrast, at 30 min, high shear-exposed HAEC exhibited an early, transient increase in NF-kappa B activity, relative to low shear-exposed cells, which reversed on continued exposure to high shear. Maximum activity in both low shear- and pulsatile low shear-conditioned HAEC was observed at 16 h compared with HAEC exposed to prolonged high shear. These results indicate that exposure of HAEC to prolonged low shear conditions is associated with significantly increased and prolonged NF-kappa B activity. This observation might provide a mechanism to explain the increased monocyte adhesion in atherosclerosisprone arterial sites exposed to chronic low-shear flow patterns.

Adaptation, Physiological↗
PubMed1997

Bioactivity of a 29-kilodalton insulin-like growth factor binding protein-3 fragment present in excess in chronic renal failure serum.

Children with chronic renal failure (CRF) have normal or high serum levels of GH, IGF-I, and IGF-II. Despite this, the serum of CRF patients has low IGF bioactivity, which may contribute to CRF growth failure. Recent studies suggest that excess IGF binding proteins (IGFBPs) in the approximately 35-kD fractions of CRF serum contribute to this low IGF bioactivity. This report characterizes a 29-kD form of IGFBP-3, IGFBP-3(29), which accumulates in the approximately 35-kD fractions of CRF serum and peritoneal dialysate. Deglycosylation and [125I]IGF ligand blot studies show that IGFBP-3(29) is a glycosylated IGFBP-3 fragment with low affinity for IGF peptides. Using an IGFBP-3 antibody column, IGFBP-3(29) was purified to homogeneity from the approximately 35-kD fractions of peritoneal dialysate from children with CRF. Compared with native IGFBP-3, pure IGFBP-3(29) has a 4-10-fold lower affinity for IGF-II and a 200-fold lower affinity for IGF-I. Consistent with the binding data, IGFBP-3(29) inhibited IGF-II-stimulated thymidine incorporation in chondrosarcoma cells, but was a less potent inhibitor than native IGFBP-3; also, native IGFBP-3 clearly inhibited IGF-I-stimulated thymidine incorporation in chondrosarcoma cells and potentiated IGF-I-stimulated aminoisobutyric acid uptake in bovine fibroblasts, but higher concentrations of IGFBP-3(29) had no effect on these IGF-I actions. Thus, the 29-kD IGFBP-3 form that accumulates in CRF serum and extravascular spaces is an IGFBP-3 fragment that may modulate IGF-II, but not IGF-I, effects on target tissues. Whether IGFBP-3(29) plays any role in the growth failure of children with CRF remains to be determined.

Animals↗
PubMed1997

Osteogenic protein-1 stimulates production of insulin-like growth factor binding protein-3 nuclear transcripts in human osteosarcoma cells.

To begin delineating molecular mechanisms by which osteogenic protein-1 (OP-1) modulates its effect on the insulin-like growth factor (IGF) system in human skeletal cells, we evaluated time-course effects of OP-1 on the expression of IGFBP-3 messenger RNA (mRNA) in human SaOS-2 osteosarcoma cells and found that 100 ng/ml of OP-1 increased (maximum 10.7-fold at 24 h; P < 0.01) the level of IGFBP-3 mRNA in a time-dependent manner (from 3-36 h; treatment x time interaction, P < 0.001). The stimulatory effect of OP-1 on IGFBP-3 mRNA was not promoted by transcript stabilization; actually, OP-1 treatment selectively increased the decay of mRNA for IGFBP-3 (T1/2 = 5 h vs. 24 h for OP-1 and controls), but not for IGFBP-4 or beta-actin. Conversely, OP-1 acutely increased IGFBP-3 nuclear transcript abundance in total RNA samples ranging between 1-24 h of treatment. After 6 h of treatment, OP-1 produced an average 4-fold increase (P < 0.02; n = 4 experiments) in the level of IGFBP-3 nuclear transcripts vs. a 3-fold increase (P < 0.01; n = 2 experiments) in mRNA abundance. The OP-1 stimulated induction of IGFBP-3 nuclear transcript and mRNA expression was dependent on de novo protein synthesis. Transient transfection experiments were undertaken to isolate putative OP-1 stimulatory cis-elements within 1.8-kb of the IGFBP-3 5'-flanking region in SaOS-2 and TE-85 osteosarcoma cells. In these experiments, OP-1 did not stimulate IGFBP-3 proximal promoter activity in either cell line, thus suggesting that OP-1 reactive domains may be located either beyond the currently established 5'-flanking region, or within internal exon/intron regions of the IGFBP-3 gene. In conclusion, OP-1 treatment stimulates IGFBP-3 expression in human osteoblastic cells by a mechanism that largely promotes the production of IGFBP-3 nuclear transcripts, a process that requires de novo protein synthesis, and overrides an OP-1-induced targeted degradation of IGFBP-3 steady-state mRNA.

Actins↗
PubMed1997

Insulin-like growth factor (IGF)-I, -II, IGF binding proteins (IGFBP)-3, -4, and -5 levels in the conditioned media of normal human bone cells are skeletal site-dependent.

The skeleton in its function of affording strength and support to the body is subject to differential mechanical loading which has been implicated to mediate some of its effects on bone formation via the insulin-like growth factors (IGFs), which are important regulators of bone metabolism. We, therefore, sought to conduct the present study with the hypothesis that the skeletal site-dependent differences in mechanical loading and other variables including stage of osteoblast differentiation would be associated with site-specific differences in the production of the IGF system components. To test this hypothesis, conditioned media (CM) from normal human bone cells (control and IGF-II-treated 48-h cultures) from five different skeletal sites were obtained and assayed for IGF-I, IGF-II (following separation of IGF binding proteins [IGFBPs]), IGFBP-3, IGFBP-4, and IGFBP-5 protein levels employing specific radioimmunoassays for each protein. IGF-I levels were lower than any other IGF system component but were significantly different between the various sites tested. IGF-II levels were greatest in the CM from mandibular cells, followed by calvarial and rib cells, and least in the marrow stromal cells. IGFBP-3 levels were highest in the CM of vertebral cells and lowest in the CM of rib and mandibular cells. The relative abundance of IGFBP-4 in decreasing order was observed in mandibular, calvarial, vertebral, rib, and stromal cells' CM. IGFBP-5 was produced maximally by the calvarial cells, followed by the mandibular, vertebral, stromal, and rib cells. IGFBP-4 appeared to be the IGF system component most abundantly produced by all the cell types from the skeletal sites tested. On a molar basis, the IGFBPs in general were estimated to be produced at a higher magnitude than the IGFs. These findings indicate that there are skeletal site-dependent differences in the production of IGF system components and suggest that the regulation of bone metabolism may vary at the various skeletal sites.

Bone and Bones↗
PubMed1997

Synthesis and evaluation of 2-chloromethyl-3-N-substituted arylthieno (2,3-d)pyrimidin-4-ones and derivatives for central nervous system depressant activity.

2-Chloromethyl 3-N-substituted arylthieno (2,3-d)pyrimidin-4-ones and derivatives were synthesized by reacting 2-amino-3-carboxanilido-4,5,6,7-tetrahydrobenzo(b)thiophenes (Iabc) with chloroacetyl chloride in dioxane and by cyclizing the open chain 3-substituted carboxanilido-2-(omega-chloroacetamido)-4,5,6,7-tetrahydrobe nzo(b)thiophenes (IIabc) under acidic condition. The compounds were characterized by their spectral data and screened for central nervous system depressant activity. The compounds IIIabc and Vabc have shown marked sedative action.

Animals↗
PubMed1996

A flexible model for the cell wall polysaccharide of Streptococcus mitis J22 determined by three-dimensional 13C edited nuclear overhauser effect spectroscopy and 13C-1H long-range coupling constants combined with molecular modeling.

We report on the conformation of a tetrasaccharide fragment in the repeating subunit of the cell wall polysaccharide of Streptococcus mitis J22, a receptor for the lectin of Actinomyces viscosus T14V in a bacterial coaggregation that is important in the ecological interactions of oral bacteria. Although there is considerable overlap of the 1H-nmr signals, some cross peaks can be extracted from conventional two-dimensional nuclear Overhauser effect spectroscopy (NOESY) data on the polysaccharide. These data cannot be fit to a single conformation of the tetrasaccharide fragment. Therefore we have prepared a polysaccharide sample fully enriched in 13C from which we have determined accurate NOESY cross-peak volumes in a three-dimensional heteronuclear-resolved spectrum that allows accurate determination of many more NOESY cross peaks than does conventional two-dimensional spectroscopy. We have also used the 13C enriched polysaccharide to measure accurate values of long-range 13C-1H coupling constants that can be correlated with glycosidic dihedral angles. Molecular modeling calculations on the polysaccharide fragment, including molecular dynamics simulations, identify multiple low-energy conformations. This result is to be contrasted with previous calculations on blood group oligosaccharides in our laboratory using similar methods that showed relatively rigid conformations with little flexibility of the glycosidic linkages. The present NOESY and 3JCH data can be reconciled with a model for the antigenic tetrasaccharide in which three distinct conformations are in fast exchange. We propose that some carbohydrate epitopes such as those of the blood group oligosaccharides are relatively rigid while others such as the tetrasaccharide fragment in these studies exhibit much greater flexibility.

Carbohydrate Conformation↗
PubMed1996

Intact insulin-like growth factor binding protein-5 (IGFBP-5) associates with bone matrix and the soluble fragments of IGFBP-5 accumulated in culture medium of neonatal mouse calvariae by parathyroid hormone and prostaglandin E2-treatment.

We examined the distribution of insulin-like growth factor binding proteins (IGFBPs) in cultured neonatal mouse calvariae. IGFBP-3 and -4 were predominantly found in the conditioned medium. IGFBP-2 was partitioned between conditioned medium and bone and extracellular matrix (BECM), while intact (31-kDa) IGFBP-5 was most abundant in BECM extracts. After treatment with parathyroid hormone (PTH, 10(-8) M) or prostaglandin E2 (PGE2, 10(-6) M), immunoreactive IGFBP-5 accumulated in the conditioned medium in a 21-kDa form which did not bind IGF-I on Western ligand blots. PTH and PGE2 did not alter the level of steady-state IGFBP-5 mRNA, nor markedly stimulate IGFBP-5 synthesis in the calvariae, and thus accumulation of 21-kDa IGFBP-5 was largely due to release from BECM. This accumulation of truncated IGFBP-5 in the conditioned medium was not dependent on osteoclastic bone resorption, since it was not blocked by calcitonin or a bisphosphonate which inhibited PTH- and PGE2-stimulated 45Ca-release. The conditioned medium from PTH- or PGE2-treated cultures degraded recombinant human IGFBP-5 into lower molecular weight fragments. Addition of IGF-1 at 10(-8) M into the culture resulted in accumulation of native 31-kDa IGFBP-5. However, even in the presence of IGF-1, the native IGFBP-5 was degraded and the 21-kDa product accumulated in the culture medium. These results suggested a possible proteolytic mechanism for 21-kDa IGFBP-5 accumulation, responsive to PTH and PGE2. Aprotinin, leupeptin, cystatin, and bestatin did not inhibit the effects of PTH and PGE2 in the cultures. The localization of IGFBP-5 in BECM and its release and proteolysis induced by PTH and PGE2 could play a role in the local regulation of bone metabolism.

Animals↗
PubMed1996

Evaluation of signal transduction mechanisms for the mitogenic effects of prostaglandin E2 in normal human bone cells in vitro.

Prostaglandin E2 (PGE2) is one of the most potent stimulators of bone formation in vivo. In these studies, we investigated the mechanism(s) underlying PGE2 effects on human bone formation by evaluating the effects of PGE2 on normal human bone cell (HBC) proliferation in vitro. Cell proliferation of normal HBCs was increased by PGE2 as measured by increased [3H]thymidine incorporation after 18 h and increased cell number after 48 h of treatment. The effect of PGE2 to stimulate cell proliferation was biphasic, with a maximum stimulation between 0.01 and 1.0 nM PGE2 in different experiments. At higher concentrations of PGE2 (0.1 microM), HBC proliferation was inhibited. Signal transduction for PGE2 has been reported to include both protein kinase A (PKA) and protein kinase C (PKC) pathways. In these studies, concentrations of PGE2 which stimulated cell proliferation did not increase cyclic adenosine monophosphate (cAMP) production. However, higher concentrations of PGE2 increased cAMP production (7- to 12-fold at 1-10 microM) and inhibited cell proliferation. Because stimulators of PKC, such as phorbol esters, have been reported to stimulate cell proliferation, the action of PKC inhibitors were tested. Both staurosporine and sangivamysin (PKC inhibitors) totally abrogated the effect of PGE2 to stimulate cell proliferation. Additional studies revealed that PGE2 increased 45Ca uptake in a dose-dependent manner with a peak response occurring between 1 and 10 nM PGE2 concentrations in different experiments. Furthermore, when the calcium channel blocker, verapamil, was added to HBC cultures treated with PGE2, the stimulation of 45Ca uptake and cell proliferation by PGE2 was completely blocked. These data suggest that PGE2 increases cell proliferation through activation of a verapamil-sensitive calcium channel. In conclusion, these data are consistent with a model in which stimulation of HBC proliferation by low doses of PGE2 is mediated by an enhancement of phospholipase C, which results in both an increase in PKC activity and an increase in intracellular calcium influx.

Analysis of Variance↗
PubMed1996

Growth factors for bone growth and repair: IGF, TGF beta and BMP.

Current research is reviewed regarding the actions of three growth factor systems on bone formation: insulin-like growth factors (IGFs), transforming growth factor-betas (TGF betas), and bone morphogenetic proteins (BMPs). Each growth factor family consists of multiple related growth factor genes. TGF betas and BMPs 2-7 are subfamilies of a larger TGF beta superfamily. IGFs, TGF betas and BMPs are produced by osteoblasts and other bone cells and affect osteoblast proliferation and differentiation. They are also incorporated into mineralized bone matrix and retain activity when extracted from bone. Various hormones, growth factors, and mechanical stress influence bone cell production of IGFs, TGF betas, and BMPs. Thus these growth factors may function in local regulation of bone formation. Currently there is much interest in the function of IGF binding proteins, which are also produced by bone cells, in regulating IGF activities in bone. Recently, mechanisms for activation of the TGF beta serine/threonine kinase receptors have been investigated, and receptors for BMPs have been identified which are structurally related to TGF beta receptors. In vivo studies are discussed which demonstrate the applicability of IGFs, TGF betas and BMPs to increasing bone formation systemically, promoting fracture healing and inducing bone growth around implants.

Animals↗
PubMed1996

Insulin-like growth factor (IGF) system components in human prostatic cancer cell-lines: LNCaP, DU145, and PC-3 cells.

BACKGROUND: Evidence has been accumulating that in many tumors, insulin-like growth factors (IGFs) promote cancer cell growth in an autocrine/paracrine manner via the IGF-I receptor. In an effort to understand the role of IGFs in prostate cancer cell growth, we characterized the IGF system components produced by human prostatic cancer cell-lines, LNCaP, DU145, and PC-3, grown in serum-free medium. METHODS: IGFs, their receptors, and IGF binding proteins (IGFBPs) produced by the three human prostate cell lines were characterized by reverse transcriptase-polymerase chain reaction (RT-PCR), radioimmunoassay (RIA), Western ligand blot, Western immunoblot, and Northern blot analyses. RESULTS: mRNA for IGF-II and receptors for IGF-I and IGF-II were detected in all three cell-lines by RT-PCR. In contrast to the published study, only LNCaP cells expressed a trace amount of IGF-I mRNA. RIA on conditioned media collected from these cells revealed that all three cell-lines produced measurable IGF-II but not IGF-I. Western Ligand blot, Western immunoblot, and Northern blot analyses revealed that LNCaP, DU145, and PC-3 cells expressed IGFBP-2, IGFBP-2/-3/-4/-6, and IGFBP-2/-3/-4/-5/-6, respectively. IGF-II stimulated [3H]thymidine incorporation into DNA in DU145 and PC-3 cells significantly although the effect was small. DNA synthesis in PC-3 cells but not in LNCaP and DU145 cells was significantly inhibited by the IGF-I receptor-specific monoclonal antibody. CONCLUSION: Theses results suggest potentially important roles of IGFs and IGFBPs in prostate cancer cell growth, and that in particular, IGF-II may play a critical role in prostate cancer cell growth.

Antibodies, Monoclonal↗