Human uterine myometrial smooth muscle cell proliferation and vascular endothelial growth-factor production in response to platelet-derived growth factor

It has been recognized that tissue-specific growth factors and angiogenic factors play important roles in the growth of tumors and in the tissue-repair system. In uterine myometrial smooth muscle cells, it has also been reported that the platelet derived growth factor (PDGF) binds to PDGF receptors and stimulates proliferation. In this paper., we examine whether or not PDGF is able to stimulate production of vascular endothelial growth factor (VEGF) in cultured human myometrial smooth muscle cells. PDGF treatment enhanced immunoreactive VEGF production as well as cell proliferation. Production of VEGF121 and VEGF165 in the cells was detected by reverse transcription-polymerase chain reaction analysis, but the PDGF treatment did not change the ratio of VEGF165 to VEGF121. The effect of PDGF on cell proliferation leveled off at 10 ng/ml, whereas its effect on VEGF production continued to increase linearly at concentrations above 10 ng/ml. Upon treatment of the cells with antibody against VEGF, the cell proliferation increased linearly even at PDGF concentrations above 10 ng/ml. The enhanced [H-3]thymidine incorporation by PDGF was abolished by either mitogen-activated protein kinase kinase (MAPKK) inhibitor or protein kinase C (PKC) inhibitor. In contrast, VEGF production was abolished by MAPKK inhibitor, but not by PKC inhibitor. These results indicate that PDGF stimulates both cell proliferation and VEGF production in partly different signal pathways, and thus PDGF might play a role in the physiology and pathology of the myometrium.