Search

This review reports studies on long-term prostate cell lines using multiple experimental approaches. The main goal was to investigate the metabolism of testosterone (T) through in vitro conversion rates. Extensive studies were also carried out on growth curves, tritiated thymidine incorporation, and morphometry by either hormone-responsive or hormone-unresponsive, normal and neoplastic human (PC3 and DU-145) and canine (CAPE and CPA) cell lines. All of them were characterized for their content of both soluble and nuclear androgen receptors. Receptor studies at site I binding in both soluble and nuclear fractions were carried out to establish the hormone sensitivity status of cells. In two prostate epithelial cells, steroid metabolic conversions in vitro show predominantly an oxidative metabolism of T, forming mainly androstenedione. Conversion rates were greater than 50% in the first 24 hours and still higher after 72 hours. At the same time and under exactly the same experimental conditions, the other cells showed metabolic pathways in which reductive metabolism prevails, dihydrotestosterone (DHT) being the prevalent metabolite. Different metabolic patterns of steroids of several cell lines relate to the hormone sensitivity status of the cells; steroid receptor-endowed cells are maintaining higher levels of unconverted precursor than are receptor-empty cells. In fact, hormone-sensitive cells, such as cancer canine CPA and human DU-145, produced DHT early through slowly converting T. On the contrary, unresponsive cells such as human cancer cells PC3 and normal canine CAPE quickly metabolize T, but DHT formation was not observed. These significant differences between cells are highly reproducible provided the proportion between cell number and molar concentration of precursors is constant. Differences we observe cannot be attributed to different experimental conditions. Cell viability, extraction efficiency, and all other parameters used for monitoring cell growth kinetics do not substantiate these reported significant differences in metabolic abilities of cells. The divergent steroid metabolic pathway we observe in different prostate long-term cells appears to be an intrinsic, consistent, highly reproducible property of each cell line.

This paper presents a short review of the results obtained to date in our laboratory, with respect to the studies of steroid excretion profiles in both breast and endometrial cancer patients, by using gas-liquid chromatographic analysis. These data demonstrate the importance of minor estrogens, including catechol estrogens, and of their ratios with the classical ones, in studies of steroid metabolism in both breast and endometrial cancer. New data concerning postmenopausal endometrial cancer are consistent with our previous observations and demonstrate the necessity of measuring these steroids directly in tumors and examining patterns of metabolism in vitro. In order to analyze steroid metabolic patterns in vitro, however, high-performance liquid chromatography rather than gas-liquid chromatography methods are preferable on account of their selectivity, specificity, sensitivity and capacity to handle labile materials. With the aim of providing methods suitable for the complete resolution and analysis of these complex natural mixtures a method of computer-aided optimization of HPLC has been developed and its practical utility has been tested.