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Human malignant epithelial cell lines were analyzed for expression of platelet-derived growth factor (PDGF) genes. Of the 12 cell lines tested, 9, derived from breast, lung, gastric, and ovarian carcinomas, were found to express both PDGF-1 and PDGF-2 genes. The levels of both PDGF-1 and PDGF-2 transcripts were superinduced when these cells were treated with cycloheximide, an inhibitor of protein synthesis. These cells also released an activity that in studies with BALB-c/3T3 cells, inhibited binding of 125I-labeled PDGF and stimulated incorporation of [3H]thymidine. This stimulating activity was inhibited after reduction of the conditioned media by mercaptoethanol or after preincubation with antibodies to PDGF. Moreover, this activity was not affected by heat treatment. Immunoprecipitation studies revealed that breast, lung, and gastric carcinoma cells produced PDGF-like proteins that migrated as 30- and 32-kD species under nonreducing conditions and as 15- and 16-kD species under reducing conditions. In contrast, malignant cells of ovarian origin produced 14-16-kD PDGF-like proteins that were unchanged in mobility after reduction. As PDGF receptors were not detected on these malignant epithelial cells, the production of PDGF-like proteins may affect other cells in the microenvironment by paracrine mechanisms and may contribute to excessive cell proliferation, inflammatory reactions, and connective tissue remodeling seen in certain carcinomas., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

Human T cells immortalized by human T lymphotropic virus (HTLV)-I and HTLV-II express the genes encoding both chains of platelet-derived growth factor (PDGF). These cells produce biologically active PDGF-like molecules of 31 and 32 kD, identified in the conditioned media of the virus-infected cells by direct immunoprecipitation, under non-reducing conditions, with antisera to PDGF. Upon reduction, the PDGF-like molecules are converted to mitogenically inactive single chains of 14 and 15 kD. The HTLV-transformed cells produce PDGF-like molecules regardless of their ability to produce viral particles. No PDGF-related mRNAs, PDGF-like proteins, nor PDGF-like mitogenic activity were detected in normal human T cells stimulated by phytohemagglutinin or in a T cell line which is not infected by HTLV. It is possible that one of the pathways of immortalization of T cells by HTLV-I or II might be by activation of PDGF-related genes., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

In human umbilical vein and bovine aortic endothelial cells in culture c-sis gene expression and secretion of platelet-derived growth factor (PDGF) has been previously demonstrated. We now report the presence of PDGF-1 and PDGF-2/sis mRNA transcripts in primary cultures of human iliac artery endothelial cells (HIA-EC). Concomitantly, these cells synthesize and secrete PDGF-like proteins identified by direct immunoprecipitation with specific PDGF antiserum. The PDGF proteins secreted by HIA-EC have molecular weights of 31 and 35 kd under nonreducing conditions. Upon reduction these proteins are converted to the monomeric 15- and 16-kd forms. Conditioned media derived from HIA-EC stimulated the incorporation of 3H-thymidine by 3T3 cells and competed with 125I-PDGF for its binding to 3T3 cell membrane receptors. The biologic activity was stable to heating at 100 degrees C for 10 min and sensitive to reducing agents, properties similar to those of authentic PDGF. Production of PDGF-like mitogen by the human arterial endothelial cells may play an important role in the paracrine modulation of arterial wall regeneration following vascular injury., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., FLWNA, info:eu-repo/semantics/published

Phorbol esters induce the differentiation of human myeloid leukemia cells HL-60 and U-937 along the monocytic-macrophage lineage. This process has been associated with the induction of several cellular protooncogenes, including the c-fos and c-fms genes. We now report that phorbol ester-induced differentiation of the HL-60 and U-937 cells results in the induction of the expression of the c-sis platelet-derived growth factor 2 (PDGF-2) protooncogene. sis mRNA transcripts were not detectable in the uninduced cells but were detectable within 12 hr of phorbol ester induction. Concomitantly, the induced cells were shown to synthesize and secrete biologically active PDGF-like proteins, identified in the conditioned medium of the phorbol ester-treated cells by direct immunoprecipitation with PDGF antiserum. Addition of cycloheximide to phorbol ester-treated HL-60 cells superinduced sis mRNA transcripts. c-sis gene transcripts were also detected in freshly isolated human monocytes but not in human granulocytes or in HL-60 cells induced to differentiate along the granulocytic lineage. Activation of the c-sis/PDGF-2 gene in human hematopoietic cells during monocytic differentiation may serve in the mediation of physiologic functions of the differentiated cells by means of the secretion of potent PDGF-like mitogen., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

Prostate carcinoma cell lines DU-145 and PC-3 express both platelet derived growth factor (PDGF)-1 and PDGF-2/sis genes. Concomitantly, these cells synthesize and secrete PDGF-like proteins, as judged by indirect immunofluorescence and by direct immunoprecipitation with specific PDGF antiserum. Conditioned media derived from DU-145 and PC-3 cells stimulated the incorporation of [3H]thymidine by 3T3 cells and competed with 125I-labeled PDGF for its binding to cell surface receptors of 3T3 cells. The biological activity was stable to heating at 100 degrees C for 10 min, sensitive to reducing agents, and neutralized by the IgG fraction of PDGF antiserum, properties similar to those of authentic PDGF. Both DU-145 and PC-3 cell lines appear to lack receptors for PDGF as indicated by their inability to mitogenically respond to PDGF and receptor binding of 125I-labeled PDGF. Production of PDGF-like proteins by human prostate carcinoma cells may play an important role in a paracrine mode in the organization of the extracellular matrix of the malignant tissue., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

Human malignant epithelial cell lines were analyzed for expression of platelet-derived growth factor (PDGF) genes. Of the 12 cell lines tested, 9, derived from breast, lung, gastric, and ovarian carcinomas, were found to express both PDGF-1 and PDGF-2 genes. The levels of both PDGF-1 and PDGF-2 transcripts were superinduced when these cells were treated with cycloheximide, an inhibitor of protein synthesis. These cells also released an activity that in studies with BALB-c/3T3 cells, inhibited binding of 125I-labeled PDGF and stimulated incorporation of [3H]thymidine. This stimulating activity was inhibited after reduction of the conditioned media by mercaptoethanol or after preincubation with antibodies to PDGF. Moreover, this activity was not affected by heat treatment. Immunoprecipitation studies revealed that breast, lung, and gastric carcinoma cells produced PDGF-like proteins that migrated as 30- and 32-kD species under nonreducing conditions and as 15- and 16-kD species under reducing conditions. In contrast, malignant cells of ovarian origin produced 14-16-kD PDGF-like proteins that were unchanged in mobility after reduction. As PDGF receptors were not detected on these malignant epithelial cells, the production of PDGF-like proteins may affect other cells in the microenvironment by paracrine mechanisms and may contribute to excessive cell proliferation, inflammatory reactions, and connective tissue remodeling seen in certain carcinomas., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

Phorbol esters induce the differentiation of human myeloid leukemia cells HL-60 and U-937 along the monocytic-macrophage lineage. This process has been associated with the induction of several cellular protooncogenes, including the c-fos and c-fms genes. We now report that phorbol ester-induced differentiation of the HL-60 and U-937 cells results in the induction of the expression of the c-sis platelet-derived growth factor 2 (PDGF-2) protooncogene. sis mRNA transcripts were not detectable in the uninduced cells but were detectable within 12 hr of phorbol ester induction. Concomitantly, the induced cells were shown to synthesize and secrete biologically active PDGF-like proteins, identified in the conditioned medium of the phorbol ester-treated cells by direct immunoprecipitation with PDGF antiserum. Addition of cycloheximide to phorbol ester-treated HL-60 cells superinduced sis mRNA transcripts. c-sis gene transcripts were also detected in freshly isolated human monocytes but not in human granulocytes or in HL-60 cells induced to differentiate along the granulocytic lineage. Activation of the c-sis/PDGF-2 gene in human hematopoietic cells during monocytic differentiation may serve in the mediation of physiologic functions of the differentiated cells by means of the secretion of potent PDGF-like mitogen., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

In human umbilical vein and bovine aortic endothelial cells in culture c-sis gene expression and secretion of platelet-derived growth factor (PDGF) has been previously demonstrated. We now report the presence of PDGF-1 and PDGF-2/sis mRNA transcripts in primary cultures of human iliac artery endothelial cells (HIA-EC). Concomitantly, these cells synthesize and secrete PDGF-like proteins identified by direct immunoprecipitation with specific PDGF antiserum. The PDGF proteins secreted by HIA-EC have molecular weights of 31 and 35 kd under nonreducing conditions. Upon reduction these proteins are converted to the monomeric 15- and 16-kd forms. Conditioned media derived from HIA-EC stimulated the incorporation of 3H-thymidine by 3T3 cells and competed with 125I-PDGF for its binding to 3T3 cell membrane receptors. The biologic activity was stable to heating at 100 degrees C for 10 min and sensitive to reducing agents, properties similar to those of authentic PDGF. Production of PDGF-like mitogen by the human arterial endothelial cells may play an important role in the paracrine modulation of arterial wall regeneration following vascular injury., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., FLWNA, info:eu-repo/semantics/published

Human T cells immortalized by human T lymphotropic virus (HTLV)-I and HTLV-II express the genes encoding both chains of platelet-derived growth factor (PDGF). These cells produce biologically active PDGF-like molecules of 31 and 32 kD, identified in the conditioned media of the virus-infected cells by direct immunoprecipitation, under non-reducing conditions, with antisera to PDGF. Upon reduction, the PDGF-like molecules are converted to mitogenically inactive single chains of 14 and 15 kD. The HTLV-transformed cells produce PDGF-like molecules regardless of their ability to produce viral particles. No PDGF-related mRNAs, PDGF-like proteins, nor PDGF-like mitogenic activity were detected in normal human T cells stimulated by phytohemagglutinin or in a T cell line which is not infected by HTLV. It is possible that one of the pathways of immortalization of T cells by HTLV-I or II might be by activation of PDGF-related genes., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published

Prostate carcinoma cell lines DU-145 and PC-3 express both platelet derived growth factor (PDGF)-1 and PDGF-2/sis genes. Concomitantly, these cells synthesize and secrete PDGF-like proteins, as judged by indirect immunofluorescence and by direct immunoprecipitation with specific PDGF antiserum. Conditioned media derived from DU-145 and PC-3 cells stimulated the incorporation of [3H]thymidine by 3T3 cells and competed with 125I-labeled PDGF for its binding to cell surface receptors of 3T3 cells. The biological activity was stable to heating at 100 degrees C for 10 min, sensitive to reducing agents, and neutralized by the IgG fraction of PDGF antiserum, properties similar to those of authentic PDGF. Both DU-145 and PC-3 cell lines appear to lack receptors for PDGF as indicated by their inability to mitogenically respond to PDGF and receptor binding of 125I-labeled PDGF. Production of PDGF-like proteins by human prostate carcinoma cells may play an important role in a paracrine mode in the organization of the extracellular matrix of the malignant tissue., Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S., info:eu-repo/semantics/published