Steroid hormone regulation of prostatic acid phosphatase expression in cultured human prostatic carcinoma cells

We have investigated the modulation of prostatic acid phosphatase expression in the human prostatic cancer cell line LNCaP in response to the natural androgens testosterone and dihydrotestosterone, the female sex steroid estradiol and the synthetic androgen R1881 (methyltrienolone). Testosterone and dihydrotestosterone at 1 microgram/ml enhance the acid phosphatase synthesis by a factor of 3.5, while a hundred-fold lower concentration of the synthetic androgen R1881 induces an almost five-fold increase in the expression of this enzyme. The stimulation by all androgens tested and estradiol was dose-dependent. The synthetic glucocorticoid triamcinolone acetonide does not modulate the prostatic acid phosphatase expression in LNCaP cells, neither alone nor in combination with R1881.     

Anti-proliferative effects of heating on the human prostatic carcinoma cells in culture

Prostatic cancers are well-known to be sensitive to heat stress. However, the mechanism by which the cancer cells are killed by high temperature remains poorly understood. The present study was undertaken to determine the anti-proliferative effects of heat stress on the prostatic cancer cells in culture. Heat shock at 43 degrees C inhibited the cell growth of three different prostatic cell lines. Flow cytometrical analysis using BrdU and PI showed a decrease in the proportion of cells in an S phase, accompanied by cell accumulation in G1 and G2, in both JCA-1 and PC-3 but not in LNcap. Both JCA-1 and PC-3 presented a strong expression of hsp70 at 37 degrees C. The heat shock caused apparent enhancement of the expression of hsp70 through the cell cycle. A treatment at 43 degrees C for 8 hours resulted in not only an apparent increment of positive hsp70 cells, but cells with subdiploid DNA content in LNcap. Flow cytometrical analysis by FITC-labeled Annexin V showed increment of apoptotic cells at 43 degrees C for 8 hours in LNcap cells. The results suggest that apoptosis is an important pathway of heat-induced killing of these cells. In conclusion, the cell growth of prostatic cancers may be affected by the temperature through relationship of the cell cycle and hsp70.     

Cholesterol modulation of the expression of mitochondrial aconitase in human prostatic carcinoma cells

Mitochondrial aconitase (mACON) is the key enzyme for the citrate oxidation in the mitochondrial Krebs cycle. Cholesterol treatment (10 microg/ml of cholesterol and 1 microg/ml of 25-hydroxycholesterol) for 24 h stimulates mACON enzymatic activity in human prostatic carcinoma cells (PC-3) and hepatoma cells (HepG2). Mevastatin, a cholesterol synthesis antagonist, blocked the effect of cholesterol treatment on mACON. The cholesterol treatment stimulated mACON enzymatic activity, which enhanced the citrate utility but decreased intracellular ATP levels in PC-3 cells. The immunoblotting and transient gene expression assays demonstrated that cholesterol treatment enhances the gene expression of mACON. Mutation of the putative sterol response element (SRE) from GACGCCCCACT to GACGCCCATAT abolished the stimulating effects of cholesterol on the promoter activity of mACON gene. The results suggest that cholesterol treatment induces the mACON gene expression through the SRE signal transduction pathway. Our study demonstrated the deregulation of cholesterol on the citrate metabolism.     

Value of the cribriformity factor in grading prostatic carcinoma.

Architectural and histometric features for the objective grading of prostate adenocarcinoma in histologic specimens were analyzed in five cases each of Gleason primary grades 2, 3A, 3B, 3C, 4A and 4B, selected as "typical" for the histopathologic images. Tissue sections from the selected cases were stained by the Feulgen method. Fifteen fields for each grade, for a total of 4,430 glands, were digitized by a video-based microphotometer at low resolution (pixel spacing of 2 microns). Outer and inner outlines of the glandular epithelium were traced manually using a mouse. For each field the number of glands, the gland area, the lumen area, the area of the glandular epithelium and the cribriformity factor were computed. The gland area and its variance proved to be useful indicators for lower-grade lesions, whereas the variance of cribriformity resulted in an excellent grading indicator in the Gleason 3-4 range when cribriform glands were present.     

Inactivation of AR activates HGF/c-Met system in human prostatic carcinoma cells

Clinical studies with prostate cancer tissue indicate that alterations in androgen receptor (AR) or c-Met overexpression are associated with androgen-independent progression. We investigated the interaction between AR and c-Met signaling in human prostate cancer cells. Androgen withdrawal or AR-specific small interfering RNA significantly reduced the growth rate while each maneuver induced the expression of c-Met. Knockdown of both AR and c-Met expression markedly inhibited the cell growth. Furthermore, microarray analysis indicated that the activation of c-Met down-regulated the expression of DNA repair-related genes including 8-oxoguanine DNA glycosylase. Exogenous hepatocyte growth factor also induced the production of intracellular reactive oxygen species and resulted in the accumulation of DNA damages. These results suggested that the activation of c-Met signaling may lead to induction of spontaneous mutations or genomic instability, which may lead to the progression of androgen-independent state. Thus, c-Met signaling is utilized for survival and growth under the androgen-depleted condition.     

Cytology of prostatic carcinoma. Quantification and validation of diagnostic criteria

The validity of diagnostic criteria for the cytologic differentiation between benign and malignant cases and between normal (hyperplastic) and inflammation-activated (prostatitis) prostatic cells was tested by means of semiautomated image analysis and cytophotometry. The following criteria were found to have significant differences between benign and malignant prostatic cells: nucleoli (number, size and size variability), regularity of nuclear arrangement, anisonucleosis, nuclear size, nuclear polymorphism and dissociation of cells. The following criteria were found to be invalid for the detection of prostatic cancer cells: nuclear-cytoplasmic ratio, hyperchromasia and anisochromasia. the cytologic diagnosis of prostatic cancer was achieved by observing a variable constellation of at least three of six pathognomically altered diagnostic criteria. No fixed pattern of diagnostic criteria was found either for prostatic cancer cells in general or for the different malignancy grades.     

The effects of estramustine on metaphase and anaphase in DU 145 prostatic carcinoma cells

The chemotherapeutic drug, estramustine, has been shown to cause the disassembly of microtubules via binding to microtubule-associated proteins. In this report, estramustine is shown to be a potent inhibitor of mitotic progression in the human prostatic carcinoma cell line, DU 145. Examination of individual living cells via video-enhanced differential interference contrast (DIC) optics shows that the drug delays the onset of anaphase, reduces anaphase spindle-pole elongation (anaphase B), and delays cytokinesis. In addition, immunofluorescent studies demonstrate that estramustine causes a rapid disorganization of the mitotic apparatus at significantly lower concentrations than those reported previously. Electron microscopic studies show that microtubule bundles are present in drug-treated mitotic cells in association with kinetochores and centrioles.     

Production of IGF-II-related peptide by an anaplastic cells line (AT-3) established from the dunning prostatic carcinoma of rats

Summary AT-3 cells, one of anaplastic cell lines established from the Dunning prostatic carcinoma of rats, were able to grow under serum-free conditions in a state of suspension detached from a substratum. Radioimmunoassays using monoclonal antibody against rat insulin-like growth factor II (IGF-II) revealed the presence of IGF-II-related peptide in acid-ethanol extracts extracsts of lyophilized serum-free media conditioned by AT-3 cell. The peptide contents in the culture media increased with increase in cell number; 71 ng at 3.0 × 10⁶ cells and 449 ng at 4.6 × 10⁷ cells. IGF-II-related peptide was hardly detectable in acid-ethanol extracts of AT-3 cells harvested after 13-days culture. These results indicate that AT-3 cells produce IGF-II-related peptide ana may release it into the culture media. Editor's statement One or more members of the insulin-like growth factor family have been established previously as mitogen for isolated prostate cells. This report suggests that IGF-II member of the family may be involved in autocrine support of cells from highly malignant prostate tumors.     

Purification of a colony-stimulating factor from cultured pancreatic carcinoma cells.

Serum-free conditioned medium prepared from an established line of human pancreatic carcinoma (MIA PaCa-2) provides a rich source of colony-stimulating factor (CSF). Two activities distinctly separable by isoelectrofocusing have been identified: a high molecular weight CSF exhibiting greater activity in mouse bone marrow and a low molecular weight CSF more active in human bone marrow. The high molecular weight CSF has been purified 1000-fold to apparent homogeneity by a two-step procedure including isoelectrofocusing and gel filtration chromatography. The purified CSF has a molecular weight of 50,000 and an isoelectric point of 3.7 to 4.6. It is a glycoprotein as shown by periodic acid-Schiff stain and exhibits greater activity in mouse marrow than in human marrow.     

Comparison of the nuclear 5 alpha-reduction of testosterone and androstenedione in human prostatic carcinoma and benign prostatic hyperplasia.

The nuclear conversion of testosterone (T) to dihydrotestosterone (DHT) and androstenedione (delta 4A) to androstanedione (5 alpha-Adione) was compared in the separated stromal and epithelial fractions of hyperplastic (n = 6) and malignant (n = 3) prostatic tissues. Assay conditions were linear with respect to time and protein concentration and were optimal for NADPH concentration. The apparent Km values for the stromal enzymes were 0.2 and 0.02 microM for hyperplasia and carcinoma, respectively, using T as substrate. The apparent Km values, using delta 4A as substrate, were 0.03 and 0.02 microM, respectively. Apparent Vmax values for the stromal formation of DHT were 16.5 +/- 5.4 and 1.97 +/- 0.45 pmol/mg protein/30 min incubation, respectively, for the hyperplastic and malignant tissues. The apparent Vmax values for the formation of 5 alpha-Adione were 2.8 +/- 1.3 and 6.5 +/- 1.2 pmol/mg/protein/30 min incubation. The apparent Km values for the epithelial enzyme, for hyperplastic and malignant tissue were 0.04 and 0.04 microM, for T, and 0.05 and 0.03 microM for delta 4A. The respective apparent Vmax values were 4.6 +/- 0.93 and 0.65 +/- 0.07 for DHT and 2.0 +/- 0.86 and 6.4 +/- 0.45 pmol/mg protein/30 min incubation for 5 alpha-Adione. delta 4A was a competitive inhibitor of T 5 alpha-reduction. These results provide further evidence that different rates of 5 alpha-reduction at least partially explain the differences in androgen levels seen in the hyperplastic and the malignant prostate.     

Serum prostate-specific antigen determination in prostatic carcinoma

Prostate-specific antigen (PSA) is a tissue-specific glycoprotein identified by Wang in 1979. It is synthesized in the prostate independently of prostatic acid phosphatase (PAP). A total of 199 subjects were divided into four groups: controls aged less than 50 years, controls aged more than 50 years, patients with benign prostatic hyperplasia (BPH) and patients with prostatic carcinoma. PSA cut-off value was set at 10 ng/ml (mean for the BPH group plus 2 SD). With this cut-off value PSA could not be used as an early predictor of prostatic carcinoma. The association of PSA and PAP in prostatic cancer increases the number of patients with positive biological markers.