Purification and Characterization of New Mammary Cell Growth Factor from Rat Pituitary Tumors : Preliminary Report.

正常大鼠乳腺上皮细胞系由大鼠乳腺细胞在化学限定的培养液中连续培养而成。通过体内移植实验、电子显微镜检查和免疫细胞化学分析，证实这些细胞为乳腺上皮来源。以这些乳腺细胞为靶细胞，建立了检测乳腺细胞有丝分裂活性的体外生物测定系统，并建立了4个大鼠促乳腺瘤细胞系(MTTF4、MTTF84)和辐射诱导的促生长激素促性腺瘤细胞系(PT1、PT3)。体外培养的垂体细胞条件培养液的有丝分裂活性分析结果表明，PT3条件培养液对乳腺细胞有很强的促生长作用。从PT3中分离出的cc152细胞具有独特的生长特性，即cc152细胞在添加了胰岛素和氢化可的松的化学定义的培养液中可以在没有任何其他促生长因子的情况下增殖。此外，来源于cc152的cc152-c3细胞能够在单独添加氢化可的松的化学定义的培养液中增殖。Cc152-c3细胞的条件培养液刺激其自身细胞的生长。糖皮质激素受体拮抗剂RV486可抑制氢化可的松对cc152和cc152-c3细胞的促生长作用。RV486还阻断了氢化可的松对条件培养液的促生长作用。这些结果表明，氢化可的松刺激CC152-C3细胞产生自分泌生长因子(S)。对条件培养液中生长因子(S)的初步鉴定表明，生长因子(S)是一种多肽。正在进行实验，以纯化和进一步鉴定糖皮质激素诱导的生长因子(S)。

Normal rat mammary epithelial cell line was established from continuous cultures of rat mammary cells in chemically defined medium. These cells were shown to be mammary epithelial origin by in vivo transplantation assay, electron microscopic examination and immunocytochemical analysis. Using these mammary cells as target cells, in vitro bioassay system for the detection of the mitogenic activity on mammary cells was developed.Four rat pituitary cell lines, derived from mammotropic pituitary tumors (MtT-F4, MtT-F84), and radiation induced somatomammotropic pituitary tumors (PT1,PT3), were also established in chemically defined medium. As the results of in vitro analysis of mitogenic activity of conditioned medium from established pituitary cell cultures, conditioned medium from PT3 was shown to have strong growth-promoting effects on mammary cells. cc152 cells, isolated from PT3, were found to have unique growth characteristics that cc152 cells could proliferate in the chemically defined medium supplemented with insslin and hydrocortisone without any other growth-promoting factors. Furthermore, cc152-c3 cells derived from cc152 were able to proliferate in the chemically defined medium supplemented with hydrocortisone alone. Conditioned medium from cc152-c3 cells stimulated the growth of their own cells. The growth-stimulating effects of hydrocortisone on cc152 and cc152-c3 cells was inhibited by the addition of a glucocorticoid receptor antagonist, RV486. RV486 also blocked hydrocortisone-induced growth-stimulating effects of conditioned medium. These results indicated that stimulation of cc152-c3 cells with hydrocortisone resulted in secretion of an autocrine growth factor (s).A preliminary characterization of the growth factor (s) in the conditioned medium suggested that growth factor (s) was a polypeptide. Experiments are being carried out to purify and further characterize the glucocorticoid-induced growth factor (s).