May J V, Frost J P, Bridge A J
Department of Obstetrics and Gynecology, University of Kansas School of Medicine-Wichita 67214.
Endocrinology. 1990 Jun;126(6):2896-905. doi: 10.1210/endo-126-6-2896.
Recent studies suggest that epidermal growth factor (EGF) and/or transforming growth factor-alpha (TGF-alpha) and insulin-like growth factor-I (IGF-I) act synergistically to promote granulosa cell proliferation in vitro suggesting a similar role in vivo. Using a serum-restricted, monolayer culture system containing very low levels of platelet-poor plasma-derived serum (PPPDS), the facilitative roles of platelet-derived growth factor (PDGF) and low density lipoprotein (LDL) with respect to growth factor-stimulated granulosa cell proliferation were investigated. In nutrient medium containing only 0.1% PPPDS, PDGF (1-25 ng/ml) had no effect upon granulosa cell proliferation. When combined with EGF, which alone does not stimulate granulosa cell proliferation, PDGF dose-dependently increased cell proliferation to levels obtained with 10% fetal calf serum (2.4-fold increase relative to controls, P less than 0.05). When combined with EGF and IGF-I, a combination which does stimulate mitosis in granulosa cells, PDGF again dose-dependently enhanced proliferation (P less than 0.05). The extent of proliferation obtained with EGF + IGF-I + PDGF was consistently greater than that obtained with 10% fetal calf serum (P less than 0.05) but significantly less than that obtained with EGF + fetal calf serum, a treatment which stimulates rapid granulosa cell proliferation. LDL has been shown to greatly enhance granulosa cell steroidogenesis by providing exogenous cholesterol. However, cholesterol is also required for plasma membrane biosynthesis and cell growth. LDL alone, had no effect upon porcine granulosa cell proliferation relative to media controls (0.1% PPPDS) nor did it synergize with any single growth factor to induce mitosis. When combined with EGF + IGF-I, and EGF + PDGF, but not PDGF + IGF-I, LDL dose-dependently (1-25 micrograms/ml) enhanced proliferation (P less than 0.05) to levels equivalent to that obtained with 10% fetal calf serum. When combined with EGF, IGF-I, and PDGF, LDL at 10 micrograms/ml enhanced proliferation to an extent equivalent with EGF + fetal calf serum (a 5.4-fold increase relative to media controls). High density lipoprotein did not itself stimulate proliferation nor did it facilitate proliferation mediated by growth factors. When maintained in medium alone (0.1% PPPDS), the cell population doubling time was 8.0 +/- 0.5 days. In the presence of EGF, IGF-I, PDGF, and LDL (10, 10, and 5 ng/ml, and 10 micrograms/ml, respectively) the doubling time was reduced to 2.0 +/- 0.1 days.(ABSTRACT TRUNCATED AT 400 WORDS)
近期研究表明，表皮生长因子（EGF）和/或转化生长因子-α（TGF-α）以及胰岛素样生长因子-I（IGF-I）在体外具有协同作用，可促进颗粒细胞增殖，提示其在体内可能发挥类似作用。利用一种血清受限的单层培养系统，该系统含有极低水平的贫血小板血浆衍生血清（PPPDS），研究了血小板衍生生长因子（PDGF）和低密度脂蛋白（LDL）对生长因子刺激的颗粒细胞增殖的促进作用。在仅含0.1% PPPDS的营养培养基中，PDGF（1 - 25 ng/ml）对颗粒细胞增殖无影响。当与单独不能刺激颗粒细胞增殖的EGF联合使用时，PDGF呈剂量依赖性地增加细胞增殖，达到用10%胎牛血清所获得的水平（相对于对照组增加2.4倍，P < 0.05）。当与能刺激颗粒细胞有丝分裂的EGF和IGF-I联合使用时，PDGF再次呈剂量依赖性地增强增殖（P < 0.05）。用EGF + IGF-I + PDGF所获得的增殖程度始终大于用10%胎牛血清所获得的程度（P < 0.05），但显著低于用EGF + 胎牛血清所获得的程度，后者可刺激颗粒细胞快速增殖。已表明LDL通过提供外源性胆固醇可极大地增强颗粒细胞类固醇生成。然而，胆固醇对于质膜生物合成和细胞生长也是必需的。相对于培养基对照（0.1% PPPDS），单独的LDL对猪颗粒细胞增殖无影响，它也不与任何单一生长因子协同诱导有丝分裂。当与EGF + IGF-I以及EGF + PDGF联合使用时，但不与PDGF + IGF-I联合使用时，LDL呈剂量依赖性地（1 - 25 μg/ml）增强增殖（P < 0.05），达到与10%胎牛血清相当的水平。当与EGF + IGF-I + PDGF联合使用时，10 μg/ml的LDL将增殖增强到与EGF + 胎牛血清相当的程度（相对于培养基对照增加5.4倍）。高密度脂蛋白本身不刺激增殖，也不促进由生长因子介导的增殖。当单独在培养基（0.1% PPPDS）中培养时，细胞群体倍增时间为8.0 ± 0.5天。在存在EGF、IGF-I、PDGF和LDL（分别为10、10和5 ng/ml以及10 μg/ml）的情况下，则倍增时间缩短至2.0 ± 0.1天。（摘要截短于400字）
