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

用化学成分确定的培养基连续培养大鼠乳腺上皮细胞，建立了正常大鼠乳腺上皮细胞系。经体内移植实验、电镜观察和免疫细胞化学分析，证实这些细胞为乳腺上皮细胞。以这些乳腺细胞为靶细胞，建立了检测乳腺细胞促有丝分裂活性的体外生物测定系统，并在化学成分确定的培养基中建立了四种大鼠垂体细胞系，即MtT-F_4、MtT-F_（84）和辐射诱导的垂体肿瘤细胞系（PT_1、PT_3）。作为来自已建立的垂体细胞培养物的条件培养基的促有丝分裂活性的体外分析结果，显示来自PT 3的条件培养基对乳腺细胞具有强烈的生长促进作用。从PT 3中分离的cc 152细胞具有独特的生长特性，即cc 152细胞可以在添加有inslin和氢化可的松的化学成分确定的培养基中增殖，而不添加任何其他生长促进因子。此外，来源于cc 152的cc 152-c3细胞能够在仅补充有氢化可的松的化学成分确定的培养基中增殖。来自cc 152-c3细胞的条件培养基刺激其自身细胞的生长。氢化可的松对cc 152和cc 152-c3细胞的生长刺激作用被糖皮质激素受体拮抗剂RV 486抑制。RV 486还阻断氢化可的松诱导的条件培养基的生长刺激作用。这些结果表明，氢化可的松刺激cc 152-c3细胞导致自分泌生长因子的分泌，条件培养基中生长因子的初步鉴定表明生长因子是一种多肽。正在进行实验以纯化和进一步表征糖皮质激素诱导的生长因子。

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).