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At least 811 records · Page 45Linked to original sources
PubMed1992

Increase in interleukin 6 (IL-6) and IL-6 receptor expression in a human multiple myeloma cell line, U-266, during long-term in vitro culture and the development of a possible autocrine IL-6 loop.

A human multiple myeloma (MM) cell line, U-266, has developed the ability to grow independently of exogenous interleukin 6 (IL-6) during long-term cultivation in vitro. The early passage, feeder-cell dependent U-266 cell line (U-266-1970) was compared with the late passage U-266-1984 cell line with respect to response to IL-6, IL-1 beta and tumour necrosis factor alpha and expression of IL-6 and IL-6 receptor (IL-6R) mRNA and protein. The results showed that; (a) only the U-266-1970 cell line was stimulated to growth by IL-6, (b) IL-6 and IL-6R mRNA were expressed in both cell lines, (c) the level of IL-6 mRNA was increased in the U-266-1984 cell line and only this line produced IL-6 and, (d) the level of IL-6R mRNA was highest in the U-266-1984 cell line and the number of IL-6R about ten times higher than in U-266-1970. The growth of the IL-6-producing U-266-1984 cell line was inhibited by 30% by anti-IL-6R antibodies suggesting the possibility that an autocrine IL-6 loop might have developed during the long-term cultivation. In addition to many other phenotypic alterations of the U-266 cell line, having developed as a consequence of tumor progression in vitro, its growth factor requirement seems to have evolved from a dependence on IL-6 as a paracrine growth factor to a capacity for autonomous growth, dependent on autocrine IL-6 stimulation. Whether such a development also may take place in MM clones in vivo remains to be established.

Blotting, Northern↗
PubMed1992

Interferon-beta. A potential autocrine regulator of human vascular smooth muscle cell growth.

Positive and negative signals regulate the proliferation in vitro of vascular smooth muscle cells (SMC), a principle cell type in the blood vessel wall. Immune interferon (IFN-gamma, a type II IFN) retards the growth of human SMC, but the effect of type I IFN (IFN-alpha or beta) is unknown. Furthermore, the capacity of SMC to produce IFN is uncharacterized. If type I IFN alters SMC growth and is produced by this cell type, an autocrine inhibitory loop could operate in vascular growth control. To test this possibility, we compared the effects of IFN-alpha, beta, and gamma on the growth of SMC stimulated by platelet-derived growth factor, interleukin-1 or tumor necrosis factor alpha. IFN-beta and IFN-gamma, but not IFN-alpha, consistently retarded growth of SMC cultures (measured by net DNA accumulation and cell number). We investigated whether SMC could produce IFN-beta, a mediator characteristically produced by fibroblasts. Vascular SMC treated with poly(I):poly(C) or tumor necrosis factor-alpha expressed IFN-beta mRNA. SMC treated with poly(I):poly(C) or Newcastle Disease virus elaborated biologically active IFN-beta as well. Our results establish that IFN-beta inhibits human vascular SMC growth and that these cells can express the IFN-beta gene. These findings show that human vascular SMC have the capacity of producing a potential autocrine growth regulator.

Base Sequence↗
PubMed2005

Autocrine growth regulation of W12 and GCA cells in culture.

Two rat kidney cell lines transformed by two strains of ASV virus were investigated. It was demonstrated that these two lines (1) showed density-independent growth, (2) had a decreased requirement for serum in the culture medium, (3) had the ability to grow in a chemically defined medium (without serum), and the rate of this growth had increased with the increase in starting density of cells, and (4) had the ability of anchrage-independent growth, even without serum. These results confirmed autostimulation of growth of W12 and GCA cells. It was also shown that the crude conditioned media contained autocrine growth factors, which could be extracted with 1M acetic acid. The extracts (AEs) stimulated the growth of the parental cells and NRK-49F cells almost as well as 5% calf serum and the extraction resulted in several-fold purification of mitogenic substances. These substances were not only specific to parental lines, but also stimulated growth of other transformed lines and normal NRK-49F cells. Extracts from the conditioned media of W12 and GCA cells intensified the rate of anchorage-independent growth in the concentration-dependent manner. In AE-W12, two peaks of mitogenic activity were detected (F1, F2) and similarly in AE-GCA (F3, F4). Fractions F2 (approximately 8 kDa), F3 (approximately 25 kDa) and F4 (approximately 12 kDa) were thermostable but F1 (approximately 45 kDa) was thermolabile. All four fractions were sensitive to trypsin and DTT treatment, and were acid-stable. Using ELISA kit it was shown that W12 and GCA cells released TGFbeta1 and GCA cells released very small quantities of bFGF. These results confirmed the autocrine regulation of growth in both cell lines.

Animals↗
PubMed1991

"Spontaneous" differentiation of skeletal myoblasts is dependent upon autocrine secretion of insulin-like growth factor-II.

Differentiation of muscle cells to form postmitotic myotubes is usually viewed as being negatively controlled by medium components, sometimes designated "mitogens." However, we have found that a family of mitogenic agents, the insulin-like growth factors (IGFs), are potent stimulators of differentiation in myoblasts which act by inducing expression of the myogenin gene. We show here that this action of the IGFs occurs even when these growth factors are not added to the cell medium; upon transfer to low-serum "differentiation medium," myoblasts begin active expression of the IGF-II gene, at both the mRNA and protein levels. Furthermore, autocrine secretion of IGF-II is essential for the process of terminal differentiation of the cells. These conclusions are based upon four lines of evidence. (1) The rate of spontaneous differentiation in several sublines of myogenic cells correlates with their level of expression of IGF-II. (2) C2 and Sol 8 cells, which secrete high levels of IGF-II, are relatively insensitive to exogenous IGFs, in contrast to L6 lines, which exhibit lower levels of IGF-II gene expression. (3) An antisense oligodeoxyribonucleotide complementary to the first five codons of IGF-II inhibits myogenic differentiation in the absence but not in the presence of exogenous IGF-II. (4) Spontaneous differentiation in response to autocrine IGF-II involves the same mechanism that occurs in cells stimulated by the IGFs, i.e. elevation of expression of the myogenin gene.

Animals↗
PubMedDate not supplied

Concomitant cell growth and differentiation are dependent on erbB1 and integrin activation in an autonomously surviving colon adenocarcinoma: involvement of autocrine amphiregulin secretion.

In normal colon epithelium, cell proliferation is followed by cell differentiation. The purpose of this work was to investigate, in the HT29-D4 colon adenocarcinoma cell line, the occurrence of a temporal sequence of changes in cell proliferation and differentiation, the role of autocrine EGF family ligands and to determine which transduction pathway(s) are involved in these processes. In a medium lacking both growth factor and serum, HT29-D4 cells secreted amphiregulin (AR), which was shown to be strongly involved in cell adhesion, growth and differentiation. In the main, integrins alpha2beta1 and alphavbeta6 intervened in these processes. Using tyrphostins, it was demonstrated that AR involvement was mediated through the ErbB1/ERK1,2 and ErbB1/FAK pathways. These signalling molecules were directly involved in pRb inhibition and, thus, in cyclin A expression. Concomitantly, colon differentiation markers were also expressed. Furthermore, terminal cell maturation resulted in a colon absorptive cell with strong polarisation, the growth of which was inhibited by tyrphostin and an ERK1,2 inhibitor. It was concluded that in a colon adenocarcinoma, cell proliferation and differentiation can occur concomitantly and that these deregulated processes are controlled by autocrine secretion through the ErbB1/ERK1,2 and FAK pathways.

Adenocarcinoma↗
PubMed2006

[Chemokine CXCL16 induces proliferation and invasion of human first-trimester cytotrophoblasts in autocrine manner].

To investigate the secretion and autocrine roles of chemokine CXCL16 in first-trimester human cytotrophoblast cells, enzyme-linked immunosorbent assay (ELISA) was used to detect the CXCL16 secretion of primary-cultured cytotrophoblast cells in various lengths of culture time and various plated densities in vitro. Then, the [3H] thymidine incorporation assay and matrigel invasion assay were applied respectively to investigate proliferation and invasion roles of CXCL16 on the cytotrophoblast cells treated with rhCXCL16. Our results showed that the primary cultured cytotrophoblasts were found to secrete in vitro CXCL16 spontaneously and continuously. CXCL16 stimulated the proliferation and invasion of cytotrophoblast cells in vitro. These results indicated that CXCL16 is secreted in first-trimester cytotrophoblast cells and induces the proliferation and invasion of cytotrophoblast cells in autocrine manner. CXCL16 plays important roles in human placentation and extravillous trophoblast invasiveness.

Cell Proliferation↗
PubMed1991

IFN-alpha induces autocrine production of IL-6 in myeloma cell lines.

IL-6 is a major tumor growth factor in human multiple myeloma. Myeloma cell lines, which have the same phenotypic characteristics and Ig gene rearrangements as the original fresh myeloma cells and whose growth is strictly dependent on exogenous IL-6 similar to fresh myeloma cells, have been reproducibly established. We show here that IFN-alpha stimulated the growth of five of six of these human myeloma cell lines by inducing an autocrine production of IL-6 in myeloma cells. Indeed, IFN-alpha induced IL-6 mRNA accumulation and IL-6 production in myeloma cells and the IFN-alpha-induced growth of these cells was inhibited by anti-IL-6 mAb. Moreover, IFN-alpha made possible the rapid emergence of autonomously growing myeloma cell sublines, which produced IL-6 as an autocrine growth factor. As IFN-alpha has a potential therapeutical interest for multiple myeloma, the present study opens up new directions for studying its effects on the myeloma clone in vivo.

Cell Division↗
PubMed1991

Production of IL-1 alpha by activated Th type 2 cells. Its role as an autocrine growth factor.

Autocrine growth of Th type 2 cells has been reported to be mediated by the lymphokine IL-4. In this report we present evidence that in addition to IL-4 Th2 cells also produce IL-1 alpha in its active form in the absence of APC. We have found that this cytokine is an autocrine growth factor, because proliferation of Th2 cells in response to several stimuli is inhibited by anti-IL-1 alpha or anti-IL-1R mAb, or by an IL-1 alpha antisense oligodeoxynucleotide. However, Th1 cells do not produce this cytokine. We have investigated the role of endogenous IL-1 alpha on the induction of c-myc and c-myb, two protooncogenes involved in T cell activation. Here we show that endogenous IL-1 alpha is involved in the activation of both protooncogenes. Our results suggest that a possible function of IL-1 alpha, and perhaps other growth factors, might be to sustain or amplify the initial second messengers derived through the TCR. The possible implications of this finding with respect to interactions between T cell subsets and B cells or macrophages are discussed.

Antibodies, Monoclonal↗
PubMed1991

Activation via the CD3 and CD16 pathway mediates interleukin-2-dependent autocrine proliferation of granular lymphocytes in patients with granular lymphocyte proliferative disorders.

Granular lymphocytes (GLs) in patients with GL-proliferative disorders (GLPDs) are known to express the interleukin-2 receptor (IL-2R) beta chain (p70-75) constitutively and to proliferate in response to stimulation with IL-2 via the beta chain. In this report, we found that the anti-CD3 monoclonal antibody (MoAb) OKT3 could induce the proliferation of GLs from patients with T-cell lineage GLPDs (T-cell receptor-alpha beta+/CD3+16+), but not that of natural killer (NK) cell lineage GLs (T-cell receptor-alpha beta-/CD3-16+). In contrast, the anti-CD16 MoAb 3G8 that reacts with NK-lineage GLs could induce the proliferation of these GLs but not that of GLs with a T-cell phenotype. Furthermore, the anti-CD16 MoAbs CLB FcR gran1 (VD2) and OK-NK, which react with both T- and NK-lineage GLs, induced the proliferation of GLs with both T- and and NK-cell phenotypes. The proliferative response induced via the CD3 or IgG Fc receptor III (Fc gamma RIII: CD16) pathway was shown to be associated with the IL-2-dependent autocrine pathway by various findings, including the induction of endogenous IL-2 production, the coexpression of the IL-2R alpha chain (p55) and the IL-2R beta chain, and the inhibition of GL proliferation by anti-IL-2 or anti-IL-2R MoAb. These results suggest that GL proliferation is mediated at least partly through the IL-2-dependent autocrine pathway, and that the TCR/CD3 complex in T-cell phenotype GLs and the Fc gamma RIII in both T- and NK-cell phenotype GLs play a role in their activation in GLPDs.

Antibodies, Monoclonal↗
PubMed1991

Lack of evidence for abnormal autocrine or paracrine mechanisms underlying the uncontrolled proliferation of primitive chronic myeloid leukemia progenitor cells.

Previous studies have revealed a consistent defect in the cycling behavior of primitive neoplastic progenitor cells in patients with Philadelphia chromosome (Ph1)-positive chronic myeloid leukemia (CML). This is manifested both in vivo and in long-term cultures of CML cells as an increased rate of turnover amongst Ph1-positive progenitor cell types whose counterparts in normal individuals are mainly quiescent. To determine whether this deregulated proliferative activity of primitive Ph1-positive cells might be explained by a perturbation in the production of growth factors that regulate the turnover of primitive normal cells, the possibility of either autocrine or paracrine mechanisms of Ph1-positive cell stimulation was investigated. Northern blot analysis of total cellular RNA extracted from various CML blood cell populations showed no evidence of increased expression of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage-CSF (GM-CSF), interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-3, IL-6, or tumor necrosis factor-alpha (TNF-alpha) compared with analogous normal peripheral blood cell populations in which transcripts for most of these growth factors are not detectable. A similar analysis of RNA extracted from the adherent layer of 4-week-old long-term cultures established from CML marrow (in which the Ph1-positive cells typically disappear) or from CML blood seeded onto normal marrow adherent layers (in which Ph1-positive cells typically persist) also revealed no difference in growth factor production compared with analogous cultures established with exclusively normal cells. For some of the growth factors studied, the assessment of bioactivity detectable in the medium confirmed the RNA data. There was also no evidence of a decreased production of putative inhibitors of primitive hematopoietic cells, i.e. transforming growth factor-beta and macrophage inflammatory protein-1 alpha by CML versus normal cells or cultures. These results do not support the existence of BCR-ABL induced autocrine or paracrine mechanisms in CML and suggest that constitutive activation of events normally dependent on growth factor receptor stimulation is more likely to underlie the lack of proliferation control exhibited by primitive Ph1-positive cells.

Bone Marrow↗
PubMed1990

Autocrine growth stimulation by secreted Kaposi fibroblast growth factor but not by endogenous basic fibroblast growth factor.

We studied the different potentials of a secreted and a nonsecreted member of the fibroblast growth factor (FGF) family to induce autocrine growth stimulation in human adrenal cortex carcinoma cells (SW-13). These epithelial cells express basic FGF (bFGF) cell surface receptors, and picomolar concentrations of bFGF suffice to induce anchorage-independent growth. The requirement for exogenously added bFGF contrasts with the intracellular storage of biologically active bFGF in SW-13 cells greater than 10,000-fold in excess of the concentration needed to stimulate anchorage independent growth. To study whether the expression of a secreted FGF would alter the growth phenotype of these cells, we transfected them with an expression vector coding for the Kaposi-fgf (K-fgf) oncogene. In contrast to controls, K-fgf-transfected cells secrete significant amounts of biologically active K-fgf protein into the growth media, show up to 50-fold increased colony formation in soft agar, and grow into rapidly progressing, highly vascularized tumors in athymic nude mice. A reversible inhibition of the autocrine growth stimulation in vitro is brought about by the polyanionic compound suramin. We conclude that FGF has to be released from SW-13 cells to function fully as a growth stimulator in vitro and in vivo.

Adenocarcinoma↗
PubMed1990

Growth inhibition of a human lymphoma cell line: induction of a transforming growth factor-beta-mediated autocrine negative loop by phorbol myristate acetate.

Transforming growth factor-beta (TGF-beta) exerts profound inhibitory effects on a number of cell types, including normal B- and T-lymphocytes. In contrast, we have found a number of lymphoid tumor cell lines to be insensitive to the antiproliferative effects of TGF-beta 1 or TGF-beta 2. Binding and cross-linking with radioiodinated TGF-beta 1 demonstrated either low or absent expression of all three TGF-beta receptor species on three B-cell tumor lines, but T-cell and non-T, non-B tumors expressed large numbers of receptors. Treatment of the B-cell lines with phorbol 12-myristate 13-acetate (PMA) induced the expression of TGF-beta receptors and inhibited proliferation in all three lines in a dose- and time-dependent manner. The cell lines constitutively produced TGF-beta mRNA and released small amounts of latent TGF-beta; however, PMA induced the release of active TGF-beta. A neutralizing antibody to TGF-beta was able to reverse the PMA-induced growth inhibition of the malignant lymphoma cell line, RL, and addition of exogenous TGF-beta reversed the effect of the neutralizing antibody. Thus, TGF-beta can inhibit human lymphoma cell growth in vitro through an autocrine mechanism. Some lymphoma cells appear to have escaped from TGF-beta negative regulation by failing to express functional TGF-beta receptors and/or by failing to secrete active TGF-beta receptors and/or by failing to acts to inhibit lymphoma cell growth is by inducing the expression of TGF-beta receptors and the secretion of active TGF-beta, thereby reestablishing an autocrine growth-inhibitory loop.

B-Lymphocytes↗
PubMed1991

Overexpression of epidermal growth factor and insulin-like growth factor-I receptors and autocrine stimulation in human esophageal carcinoma cells.

The growth-stimulatory effects of epidermal growth factor (EGF), transforming growth factor alpha (TGF-alpha), and insulin-like growth factor-I (IGF-I) on the human esophageal carcinoma cell line CE48T/VGH were evaluated. Under serum-free conditions, EGF, TGF-alpha, and IGF-I promoted 3.6- to 4.1-fold increased cell proliferation. Scatchard analyses and Northern blot hybridization revealed that both the EGF/TGF-alpha receptor and the IGF-I receptor were overexpressed in CE48T/VGH cells. Furthermore, ligand-dependent autophosphorylation of the EGF receptor and the IGF-I receptor was clearly detected using antireceptor and antiphosphotyrosine antibodies. Autocrine regulation was strongly indicated by the following evidence: (a) CE48T/VGH cells were found to express TGF-alpha and IGF-I genes, (b) serum-free conditioned medium promoted the growth of CE48T/VGH cells and stimulated the autophosphorylation of the EGF/TGF-alpha receptor and the IGF-I receptor, and (c) the addition of IGF-I receptor antibodies significantly suppressed CE48T/VGH cell growth under serum-free conditions. Our studies suggest that the overexpression of EGF and IGF-I receptors and autocrine growth regulation may concertedly control the proliferation of esophageal carcinoma cells.

Animals↗
PubMed1991

IL-6 and tumor necrosis factor-alpha. Autocrine and paracrine cytokines involved in B cell function.

IL-6 and TNF-alpha are synthesized and secreted by normal tonsillar B cells after stimulation with the polyclonal B cell activator Staphylococcus aureus Cowan strain 1 (SAC) and IL-2 as well as spontaneously by in vivo activated B cells from patients with hypergammaglobulinemia. Using specific neutralizing antibodies, both factors were shown to be involved in autocrine and/or paracrine regulation of B cell differentiation. IgG induced by SAC/IL-2 stimulation was reduced 73% with an anti-IL-6 antibody and 40% with an anti-TNF-alpha antibody. Similar effects of these antibodies were observed on the spontaneous in vitro IgG production by lymphoblastic B cells from six patients with hypergammaglobulinemia. Kinetic studies with SAC/IL-2-activated B cells revealed that the anti-TNF-alpha antibody must be present at the beginning of the culture to exert an effect on Ig production, whereas the anti-IL-6 antibody reduced Ig production even if added as late as day 3. This sequential action of TNF-alpha and IL-6 on B cell differentiation was reflected by different kinetics of release of these two cytokines into the supernatant of SAC/IL-2 activated B cells; TNF-alpha peaked at 24 h and IL-6 at 96 h after stimulation. In addition, it was shown that IL-6 production by in vitro-activated B cells was partially blocked by an anti-TNF-alpha antibody suggesting that TNF-alpha regulates IL-6 production in normal B cells via an autocrine pathway. We also investigated the effects of TGF-beta on TNF-alpha and IL-6 production by normal B cells. Although TGF-beta inhibited Ig production by in vitro-activated and in vivo-activated B cells, it did not inhibit the release of these cytokines from normal B cells. Furthermore, TGF-beta did not inhibit the induction of nuclear factor-IL-6 nor the expression of IL-6R on activated B cells. Thus, although the biologic effects of anti-IL-6 and TGF-beta on B cell Ig production are similar, their mechanisms of actions appear to be distinct.

B-Lymphocytes↗
PubMed1991

Proliferation of Shionogi carcinoma 115 cells by glucocorticoid-induced autocrine heparin-binding growth factor(s) in serum-free medium.

Shionogi carcinoma 115 (SC115) has been accepted for 20 years as an androgen-responsive mouse mammary tumor. Recently, the growth of the tumor was also found to be stimulated by pharmacological, but not physiological, doses of glucocorticoid. In a serum-free culture system [Ham's F-12:Eagle's minimal essential medium (1:1, v/v) containing 0.1% bovine serum albumin], we have established that 10(-8) M testosterone, or 10(-6) M dexamethasone significantly stimulates the growth of SC-3 cells (a cloned cell line from a SC115 tumor) via androgen and glucocorticoid receptors, respectively. Recently, we demonstrated that the testosterone-induced growth of SC-3 cells is mediated through autocrine fibroblast growth factor (FGF)-like peptide(s). In the present study, mechanisms of glucocorticoid-induced growth of SC-3 cells were investigated. Serum-free conditioned medium obtained from 10(-6) M dexamethasone-stimulated SC-3 cells was fractionated by heparin-Sepharose affinity chromatography; one sharp peak of growth-stimulatory activity for SC-3 cells, eluted at 1.3 M NaCl, was identified. When the peak fraction was added to serum-free medium, the shape of SC-3 cells changed from an epithelial to a fibroblast-like appearance, similar to that induced with testosterone or basic (b)FGF. Furthermore, the growth-stimulatory activity induced with the peak fraction as well as testosterone or bFGF was markedly inhibited by anti-bFGF antibody immunoglobulin G (75 to 90% inhibition was obtained), and the specific binding of 125I-bFGF on SC-3 cells was significantly inhibited by the peak fraction. These results suggest that the glucocorticoid-induced growth of SC-3 cells is also mediated through FGF-like peptide(s) in an autocrine mechanism, which is very similar to that induced by testosterone, if not identical.

Animals↗
PubMed1991

Tumorigenic transformation of NIH 3T3 cells by the autocrine synthesis of transforming growth factor alpha.

A variety of cancer cells overexpress transforming growth factor alpha (TGF alpha), a mitogenic peptide. A cDNA sequence coding for the full-length human TGF alpha precursor protein was subcloned into a retroviral expression vector and introduced into clone 7 NIH 3T3 cells, which have low numbers of endogenous epidermal growth factor receptors (EGFRs). The autocrine synthesis of TGF alpha by these cells resulted in their focal transformation. In contrast, control NIH 3T3 cells treated in a paracrine manner with exogenous, saturating concentrations of the mature form of TGF alpha, though stimulated to divide, remained morphologically untransformed. The addition of saturating quantities of soluble, mature TGF alpha to NIH 3T3 cells expressing the transferred TGF alpha gene actually suppressed their growth and focal transformation. The transformation induced by the TGF alpha gene remained an EGFR-dependent process, since the degree of transformation was correlated with EGFR expression in NIH 3T3 cells and since NR6 cells, which are Swiss 3T3 cells devoid of endogenous EGFRs, were transformed by the TGF alpha vector only when exogenous EGFR genes were also introduced. When inoculated into nude mice, the TGF alpha-expressing cells rapidly gave rise to tumors that grew progressively, whereas control cells did not form tumors. We conclude that in certain circumstances autocrine TGF alpha can be more oncogenic than paracrine and that paracrine TGF alpha can suppress this effect.

Animals↗
PubMed1990

Inhibition of murine monocyte proliferation by a colony-stimulating factor-1 antisense oligodeoxynucleotide. Evidence for autocrine regulation.

Using a combination of v-myc and v-ras oncogenes, we have established a growth factor-independent monocyte cell line from murine fetal liver (FL-ras/myc). Biologic and molecular characterization demonstrated that the gene for the macrophage growth factor CSF-1 and the c-fms proto-oncogene (CSF-1 receptor) are expressed in this cell line, thus suggesting autocrine regulation as a possible mechanism for the unregulated growth of these cells. To study this possibility, we used 1) mAb, to neutralize the CSF-1 protein produced by the cell line, and 2) antisense oligomers, to inhibit CSF-1 gene products by specific base-pairing of complementary nucleic acids. We report here that both approaches inhibited in vitro cell growth by 60 to 70%, whereas the combination of oligomer and mAb inhibited proliferation by 95%. However, control antisense oligomers (50% bp mismatch with CSF-1 mRNA) did not inhibit FL-ras/myc cell growth. Furthermore, the inhibitory effects of mAb and oligomers were reversible when they were removed from the media. Detection of cell-associated CSF-1 protein by immunofluorescence showed that cells treated with the antisense oligomer expressed significantly less CSF-1 protein. These results indicate that the FL-ras/myc cell line requires CSF-1 for autonomous growth and that oligomers can efficiently block production of autocrine growth factors.

Animals↗
PubMed1990

Insulin-like growth factor I and transforming growth factor alpha as autocrine growth factors in human pancreatic cancer cell growth.

The roles of insulin-like growth factor I (IGF-I) and transforming growth factor alpha (TGF-alpha) as autocrine factors in the proliferation of MIA-PaCa 2 cells (human pancreatic cancer cells, PC cells) were investigated. Furthermore, the mechanism(s) of inhibition of PC cell growth by a phorbol ester in relation to these two kinds of growth factor was also studied. PC cells grew autonomously when Dulbecco's modified essential medium supplemented with 4% fetal calf serum was changed to serum-free medium (0.3% bovine serum albumin-Dulbecco's modified essential medium). In addition, serum-free conditioned medium from PC cells dialyzed against fresh Dulbecco's modified essential medium had a stimulatory action on the growth of the same kind of cells when compared with that induced by nonconditioned medium. These observations suggest that a factor(s) produced and released by PC cells stimulates their own growth. Analysis of conditioned medium from PC cells revealed the presence of immunoreactive (IR)-IGF-I and IR-TGF-alpha. The molecular size of IR-IGF-I was similar to that of authentic IGF-I. On the other hand, IR-TGF-alpha was present as multiple forms when analyzed using gel chromatography. Authentic IGF-I and TGF-alpha added to culture medium stimulated PC cell growth by 1.45- and 1.5-fold above control value, respectively. A monoclonal antibody to IGF-I receptor was able to inhibit PC cell growth. PC cell proliferation was markedly inhibited by 12-O-tetradecanoyl-13-acetate (greater than 0.16 nm), whereas cell growth of human fibroblasts was stimulated by it. 12-O-Tetradecanoyl-phorbol-13-acetate also reduced the binding of 125I-TGF-alpha, but not 125I-IGF-I, to PC cells. Decrease in TGF-alpha binding was mainly due to the reduced affinity of receptors to the ligand. These results suggest that IGF-I and TGF-alpha are involved in PC cell proliferation as autocrine factors. Further, the inhibition of PC cell growth by phorbol ester could be, at least partly, due to the decreased binding of TGF-alpha to the cells.

Adult↗