Castagnetta L A, Granata O M, Taibi G, Lo Casto M, Comito L, Oliveri G, Di Falco M, Carruba G
Experimental Oncology Unit, Palermo Branch of the National Cancer Institute of Genoa, Palermo, Italy.
J Endocrinol. 1996 Sep;150 Suppl:S73-8.
This paper summarizes our most recent results of steroid enzyme studies on cultured breast and endometrial cancer cells. It deals mainly with estrogen 17 beta-hydroxysteroid oxidoreductase (17 beta HSOR) activity, which presides over estradiol (E2) and estrone (E1) interconversion, a major metabolic pathway of estrogens. Assessment of either the oxidative or reductive component of 17 beta HSOR was carried out on intact cells by means of an original approach based on reverse phase-high performance liquid chromatography and radioactive detection on line. This system allows the continuous monitoring of both precursor degradation and formation of several radiometabolites to assess rates and direction of steroid metabolism. Overall, hormone-responsive, estrogen receptor (ER)-positive cells, regardless of whether they were derived from breast (MCF7) or endometrial (Ishikawa) tumor tissues, showed a prevalence for reductive metabolism (E1-->E2), whilst oxidative pathways (E2-->E1) were largely dominant in non-responsive, ER-poor mammary (MDA-MB231) and endometrial (HEC-1A) cells. The above estimates of 17 beta HSOR activity were at variance with those obtained using the classical enzymology approach, not only in quantitative terms (being markedly lower using intact cell analysis), but also because the prevalent direction of estrogen metabolism was often reversed. Although striking methodological differences may well account for this discrepancy, intact cell analysis is undoubtedly more similar to the in vivo state than the artificial requirements of classical enzymology procedures.
本文总结了我们对培养的乳腺癌和子宫内膜癌细胞进行类固醇酶研究的最新结果。它主要涉及雌激素17β-羟基类固醇氧化还原酶（17βHSOR）活性，该酶负责雌二醇（E2）和雌酮（E1）的相互转化，这是雌激素的主要代谢途径。通过基于反相高效液相色谱和在线放射性检测的原始方法，对完整细胞进行了17βHSOR氧化或还原成分的评估。该系统允许连续监测前体降解和几种放射性代谢物的形成，以评估类固醇代谢的速率和方向。总体而言，激素反应性、雌激素受体（ER）阳性细胞，无论它们是源自乳腺（MCF7）还是子宫内膜（Ishikawa）肿瘤组织，都表现出还原代谢（E1→E2）的优势，而氧化途径（E2→E1）在无反应性、ER含量低的乳腺（MDA-MB231）和子宫内膜（HEC-1A）细胞中占主导地位。上述17βHSOR活性的估计值与使用经典酶学方法获得的估计值不同，不仅在数量上（完整细胞分析得到的结果明显较低），而且因为雌激素代谢的主要方向经常相反。尽管显著的方法学差异很可能解释了这种差异，但完整细胞分析无疑比经典酶学程序的人为要求更类似于体内状态。
