Stromal and epithelial cells of the canine prostate express parathyroid hormone-related protein, but not the PTH/PTHrP receptor

BACKGROUND

Parathyroid hormone-related protein (PTHrP), a principal factor in the pathogenesis of humoral hypercalcemia of malignancy, is also widely expressed in many normal tissues, including human prostatic epithelial cells. The role of PTHrP in the prostate is not known, but may include regulation of cell growth and differentiation or calcium secretion into prostatic fluid. The dog is a valuable animal model for human prostatic diseases. The objective was to investigate the expression of PTHrP and the PTH/PTHrP (type 1) receptor in primary cultures of canine stromal and epithelial prostatic cells.

METHODS

Expression and secretion of PTHrP and the PTH/PTHrP receptor was measured in homogeneous primary cultures of canine prostatic stromal and epithelial cells using immunohistochemistry, Northern blots, radioimmunoassay, RT-PCR, and receptor stimulation assays.

RESULTS

Epithelial and stromal cells expressed and secreted abundant PTHrP, but PTH/PTHrP receptor expression was not detected in either cell type.

CONCLUSIONS

PTHrP expression by stromal and epithelial prostatic cells and the absence of the PTH/PTHrP (type I) receptor suggest that some functions previously proposed for PTHrP in the prostate are unlikely. The separation procedure presented is a valuable tool for studying the role and regulation of PTHrP in the prostate.

Assessment of cardiac autonomic nervous activities during heliox exposure at 24 atm abs

BACKGROUND

This experiment was designed to examine the involvement of the autonomic nervous system in the production of hyperbaric bradycardia.

METHODS

Four male divers were exposed to a He-O2 (heliox) environment at 24 atmosphere absolute (atm abs) for 7 d. The heart rate (HR) and respiratory rate were recorded at rest in the morning (0700 h) and at night (2230 h) on 1 d during a 5-d predive control, 2 d during a 7-d saturation dive at 24 atm abs, 2 d during decompression, and on 1 d during a 4-d postdive period. Cardiac sympathetic and parasympathetic activities were estimated by using a spectral analysis of the variability of R-R intervals.

RESULTS

The morning HR did not fluctuate throughout the experimental days. The night time HR decreased (p < 0.05) by 11.8% on the first day at 24 atm abs compared with that of the predive control. The bradycardia diminished gradually and returned to the predive level with continued exposure at 24 atm abs. The high-frequency power of the cardiac variability, an index of cardiac parasympathetic activity, increased (p < 0.05) only in the first night at 24 atm abs, whereas the low-frequency power and a ratio of low- to high-frequency power, an index of cardiac sympathetic activity, were unchanged.

CONCLUSIONS

The present results suggest that an increased parasympathetic activity rather than a decrease in the sympathetic activity is responsible for the bradycardia on exposure to heliox dry saturation dive at 24 atm abs. The mechanism of the gradual disappearance of the bradycardia is unknown, but perhaps it may be related to the development of cardiovascular deconditioning.

The correlation of telomerase and IL-10 with leukemia transformation in a mouse model of chronic lymphocytic leukemia (CLL)

Telomerase activity is upregulated in activated and malignant lymphocytes. We studied the correlation of telomerase and IL-10 to leukemia transformation in the NZB mouse model of human chronic lymphocytic leukemia (CLL). Telomerase levels increased from early to late leukemic stages, likewise IL-10 gene expression levels increased with the leukemic progression. The inverse relationship of telomerase and IL-10 levels to the survival of NZB mice was also established. Our data suggested that telomerase and IL-10 were involved in transformation in the murine model of CLL and the detection of telomerase activities might be of value in the prediction of CLL progression.

Weekly 24 h infusion of high-dose 5-fluorouracil and leucovorin in patients with biliary tract carcinomas

From October 1995 to June 1997, 19 chemotherapy-naive patients with pathology-proven locally advanced or metastatic biliary tract carcinomas (BTC) were enrolled. The regimen consisted of 5-fluorouracil (5-FU) 2600 mg/m2 and leucovorin (LV) 150 mg by weekly 24 h infusion for 6 weeks and followed by a 2 week break. The treatment was terminated if disease progressed, the patient refused or unacceptable toxicity occurred. All patients required a Port-A catheter insertion and were treated at outpatient clinics by portable infusion pumps. There were 12 males and seven females with a median age of 62 years (range 45-77). The primary tumor sites were nine intrahepatic cholangiocarcinomas (CC), three perihilar CC, one distal BTC and six gallbladder cancers. A total of 179 chemotherapy sessions were given with a mean of 9.5 (range 2-18). Eighteen patients were evaluable for response. The response rates were: 33% (six of 18) partial response (PR), 39% (seven of 18) stable disease (SD) and 28% (five of 18) progressive disease (PD). All of the patients were evaluable for toxicity. The most common toxicities were mild fatigue (nine of 19, 47%), loss of appetite (nine of 19, 47%), skin hyperpigmentation (five of 19, 26%) and diarrhea (two of 19, 11%). Only one patient had grade IV myelotoxicity with sepsis but without treatment-related death. The median time to progression was 4 months. The overall median survival time was 7.0 months. The median survival time of the PR was not reached, SD was 8.0 months and PD 3.5 months. In conclusion, weekly high-dose 5-FU with LV by 24 h infusion in an outpatient setting for patients with BTC is effective, only mildly toxic and deserves further study.

Partial purification and characterization of two non-FSH steroid-modulating factors in rat thymic epithelial cell-conditioned medium (TCM)

Previously, we have reported that unknown factor(s) in rat thymic epithelial cell-conditioned medium (TCM) stimulates basal and follicle-stimulating hormone (FSH)-induced steroid hormone production and aromatase enzyme activity in cultured rat granulosa cells. Here we report the partial purification and characterization of two of these activities. Thymic epithelial cells were prepared from immature female rats and used for TCM production. Lyophilized aliquots of TCM were reconstituted with distilled water at 25% of the original volume, applied to a gel filtration column, and column fractions were tested for their stimulation of steroidogenesis in granulosa cells prepared from immature diethylstilbestrol-treated rats. Two distinct biologically active regions were identified that corresponded to apparent molecular weights of approximately 22,000 and less than 1,000. The < 1 kDa activity ("TCM-1") stimulated (P < 0.01) basal production of progestins [progesterone and 20 alpha-hydroxypregn-4-en-4-one (20 alpha-OH-progesterone)] and estrogen, and also induced dramatic morphological changes on the rat granulosa cells. In contrast, the approximately 22 kDa activity ("TCM-22") stimulated (P < 0.01) only basal progestins, and had no effect (P < 0.05) on basal estrogen production or morphology of the cultured rat granulosa cells. In the presence of 100 ng/ml FSH, TCM-1 stimulated (P < 0.01) estradiol and progesterone production, whereas TCM-22 stimulated (P < 0.01) progesterone, but inhibited (P < 0.01) estradiol production. When both activities were assayed together, they were synergistic in stimulating (P < 0.01) basal progesterone production, but TCM-22 antagonized (P < 0.01) TCM-1-induced estradiol production. The biologic and physico-chemical characteristics of TCM-1 and TCM-22 were distinct from one another, as well as from FSH. When subjected to C8 reverse-phase HPLC. TCM-1 retained its characteristic biologic properties and was eluted (54% acetonitrile) as A214-absorbing moiety with a peak retention time of 92-93 minutes. The elution of TCM-22 was not correlated with an identifiable protein peak. These results suggest that ovarian steroid production may be modified by non-FSH factors produced by thymic epithelial cells although amino acid sequencing of TCM-1 was unsuccessful. This highlights a potential role of the thymus gland in regulating ovarian function.

Estrogen-induced keratinocyte growth factor mRNA expression in normal and cancerous human breast cells

The local recurrence rate of breast cancer has been reported to be unusually high at the surgical scar. Such breast cancer recurrence is believed to be triggered by the release of growth factors into the healing wound. Observations from an animal model have also demonstrated that KGF expression is dramatically induced by creation of full thickness wounds in mouse skin. Since KGF is an epithelial cell-specific mitogen in rat mammary epithelium, it is reasonable to speculate that KGF may be also involved in regulating human breast cancer cell growth. The purpose of the present study was to determine the effect of estradiol-17 on KGF gene expression in normal human breast stromal cells, as well as in human breast cancer stromal cells, and the mechanisms by which estradiol-17 regulates breast epithelial proliferation. Our results show that KGF expression was not effected by estradiol-17 treatment in normal human breast stromal cells. In contrast, KGF expression was stimulated by estradiol-17 in human breast cancer stromal cells. KGF mRNA levels have also been examined in normal human breast stromal cells and human breast cancer stromal cells. An interesting correlation was found between KGF expression and estradiol-17 regulation in these cell types. Normal human breast stromal cells which do not response to estradiol-17 have lower KGF mRNA level than the cancer cells which KGF expression is stimulated by estradiol-17. Our data also demonstrate that recombinant human KGF significantly stimulate normal human breast and human breast cancer epithelial cell proliferation in a dose-dependent manner. Since we have shown that estradiol-17 induces KGF mRNA expression in human breast cancer stromal cells, KGF may be involved at least in part in the stimulatory pathway that is initiated by estradiol-17 in human breast cancer epithelial cells.

Decreased PDGF receptor kinase activity in fibroblasts contracting stressed collagen matrices

Fibroblasts cultured in mechanically stressed collagen matrices proliferate, whereas cells in floating collagen matrices become quiescent. Previous research indicated that one factor contributing to cell quiescence in floating matrices was reduced receptor autophosphorylation in response to PDGF stimulation (i.e., PDGF receptor desensitization). To learn more about the mechanism of PDGF receptor desensitization, we analyzed changes in PDGF receptor autophosphorylation and receptor kinase activity after stressed collagen matrices were switched to floating conditions, which results in rapid cell contraction and dissipation of mechanical stress. PDGF receptor desensitization occurred during contraction stimulated by serum but not in the absence of serum, and desensitization was prevented by inhibitors of contraction but not by inhibitors of the contraction-activated cyclic AMP signaling pathway. Receptor desensitization resulted from decreased receptor kinase activity rather than from elevated protein tyrosine phosphatase activity, and only receptors unoccupied at the time of contraction were affected. After contraction, radiolabeled PDGF binding to the cells was decreased, which suggested that receptor desensitization resulted from a contraction-dependent change in receptor availability or affinity.

A study to evaluate the parent-offspring similarity in the maxillofacial profile using fingerprints in Japanese families

An attempt was made to investigate the parent-offspring similarity in the maxillofacial profile by a quantitative analysis of fingerprints. Lateral roentgenographic cephalograms and ten fingerprints were obtained from 98 Japanese patients (44 males and 54 females) and their parents. Analysis showed a significant parent-offspring correlation for both maxillofacial profile and fingerprints. The relatively low father-son correlation for both features suggests a major influence of X-linked genes. The genetic correlation between the maxillofacial profile and fingerprints was significant for parent-son but not for parent-daughter pairings. The parent-offspring correlation in the maxillofacial profile was evaluated in two groups showing differences (distant group) or similarities (near group) in the fingerprint patterns between the father and mother. In the distant group, a greater parent-offspring similarity was observed in the maxillofacial profile. The same finding was also obtained on using only digit II of the parents. Therefore, from a morphogenetical point of view, parental fingerprints appear helpful in clinical applications designed to predict maxillofacial growth in offspring.

Synthesis of 2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carbonitriles as ATP-sensitive potassium channel openers

A series of optically active tetrahydro-oxazino[2,3-c]benzopyran derivatives have been synthesized and evaluated for potassium channel opening activity. (4aR,11bR)-1-Benzoyl- 5,5-dimethyl-2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carb onitrile ((-)-11e) was identified as a bladder-selective potassium channel opener (IC50, bladder = 8.15 microM, IC50, portal vein = 34.5 microM).

Diving pattern and work schedule of construction well divers in Taiwan

Construction well divers in Taiwan reportedly suffer a high prevalence of dysbaric osteonecrosis. We studied five divers working at the same construction site. We recorded their diving methods, diving depths, bottom times, work patterns, water temperatures, and heart rates. We also monitored gas bubbles in the subclavian vein in selected dives. A crude but effective hot-water system protected divers against hypothermia and allowed them to work in 24 degrees-27 degrees C water. Divers worked approximately 6.6 h a day and progressed approximately 3.0 m a day while excavating an average of 148 buckets of sand and rock each weighing 49.5 kg. The divers sustained a heart rate increase of 49%. Sixty percent of their equivalent single dive bottom times exceeded the U.S. Navy's no-decompression limits. Two cases of venous bubbles were detected, and one of these divers showed symptoms of decompression sickness. The prolonged bottom time and lack of a decompression schedule probably contributed to a risk of decompression sickness and dysbaric osteonecrosis.

Plasma concentrations after rectal administration of acetaminophen in preterm neonates

Acetaminophen is frequently administered to infants and children for its antipyretic and analgesic properties. Oral administration is the route of choice in daily practice. In some circumstances this is impractical. Rectal administration of acetaminophen is an alternative route. This study measures plasma concentrations following rectal administration of acetaminophen 20 mg.kg-1 (10% Infants' Tylenol Drops, McNeil Consumer Product Co., diluted with an equal volume of sterile water) in five preterm neonates. Serial arterial blood samples were obtained at 0, 15, 30, 60, 120, and 240 min. Pharmacokinetic parameters were (mean +/- SD): Cmax (maximum plasma concentration) of 8.38 +/- 3.92 micrograms.ml-1 and Tmax (time to reach maximum plasma concentration) of 78.0 +/- 40.2 min. Our results show that 20 mg.kg-1 of acetaminophen rectally results in low plasma levels in preterm neonates.

Differential effect of keratinocyte growth factor (KGF) on aromatase activity in cultured canine prostatic epithelial cells

We have recently cloned the mRNA encoding KGF from canine prostate and produced recombinant canine KGF (rcKGF) which specifically acts on cultured canine prostatic epithelial cells (CCPECs) which possess KGF receptors (Canatan et al., 1996; DNA Cell Biol. 15:247). In the present study, the effect of rcKGF on aromatase activity in CCPECs from young (6-month-old) and mature (3-year-old) dogs was examined. Release of 3H2O from labeled substrate was used as the indicator of aromatase activity. CCPECs were pulsed with [1-beta-3H]-androstenedione (1 microCi/ml, 6 hr). The amounts of 3H2O released into culture medium were measured (dpm) and total cellular proteins were determined. Aromatase activity was expressed as 3H2O dpm/mg cellular protein (mean +/- SEM). The basal level of aromatase activity in CCPECs from mature dogs was approximately 4 times higher (p < 0.05) than that in cells from young dogs. Aromatase activity in CCPECs from mature dogs increased in a dose-dependent manner upon treatment with rcKGF. Interestingly, rcKGF, at any of the concentrations tested, had no significant effect on aromatase activity in CCPECs from young dogs. These results are the first to indicate that aromatase activity is affected by KGF in mature CCPECs, suggesting that KGF may be involved indirectly in the etiology of benign prostatic hyperplasia by increasing aromatase activity and thus increasing aromatization of androgens. Aromatase induction by KGF may explain, at least in part, the increased aromatization of androgens observed in aged dogs. The exact mechanism of how KGF induces aromatase activity in CCPECs is needed to be addressed further.

Cigarette smoking and smoking cessation among older adults: United States, 1965-94

OBJECTIVE

To characterise patterns of cigarette smoking and smoking cessation among older adults in the United States.

DESIGN

Data from the National Health Interview Surveys (NHIS) 1965-94 were analysed. The NHIS is a cross-sectional survey using a representative national sample.

SETTING

In most cases interviews were conducted in the home; telephone interviews were conducted when respondents could not be interviewed in person.

PARTICIPANTS

Participants were from a representative sample of the American civilian, non-institutionalised population aged 18 and older. Sample sizes for the years analysed ranged from n = 19,738 to n = 138,988 overall, and n = 3806 to n = 12,491 for those aged 65 years and older.

MAIN OUTCOME MEASURES

Using the NHIS data from 1965-94, trends in current smoking and the prevalence of smoking cessation by demographic characteristics among older adults (65 years and older) were assessed and compared with trends among younger adults. A logistic regression analysis was conducted to determine the demographic characteristics of former smokers compared with current smokers among those aged 65 and older.

RESULTS

The prevalence of current smoking among 65 year olds and older declined from 1965 to 1994 (17.9% to 12.0%). Although smoking prevalence was lower among older adults than younger adults (aged 18-64), the rate of decline in smoking was slower among older adults. Among older adults, the prevalence of cessation rose with increasing educational attainment, and was consistently higher for men than for women and for whites compared with blacks. After adjustment for demographic factors among older adults who had ever smoked, increasing age and educational attainment were strongly related to the likelihood of being a former smoker. Although there were no racial differences among women, older white (OR = 2.6) and Hispanic (OR = 3.67) men were significantly more likely to be former smokers than older black men. Also, the gender difference in smoking cessation was noted only for whites.

CONCLUSIONS

Given the projected increase in the elderly population, the medical and economic consequences of smoking will become a greater burden in the next decades. Therefore, focusing attention on cessation among the elderly is an immediate and urgent priority for public health professionals and clinicians.

Effects of heat treatment and physical processing of cottonseed on nutrient digestibility and production performance by lactating cows

Four primiparous Holstein cows were used in an experiment with a 5 x 4 Youden square design. The effects of heat processing and particle size of cottonseed used in the diets of dairy cows were investigated. Dietary treatments were control (3.6% tallow, 4.5% casein), whole cottonseed, ground cottonseed, roasted whole cottonseed, and roasted ground cottonseed. Diets consisted of 55% corn silage, 1.54% urea, and cottonseed at 18.1% or dry matter. Cottonseeds were roasted at 149 degrees C and steeped for 30 min. Roasting increased the amount of ruminally undegradable protein measured in vivo, the ratio of ruminal acetate to propionate, pH, and milk protein percentage. Ruminal digestibilities of organic matter (OM) and neutral detergent fiber and biohydrogenation of fatty acids were reduced by roasting. The grinding of cottonseed increased the total tract digestibility of OM and N and tended to increase ruminally undegradable protein of cottonseed in vivo. Interactions between heat treatment and particle size of cottonseed revealed that roasted ground cottonseed resulted in the highest total tract digestibility of OM, N, and neutral detergent fiber. Utilization of cottonseed may be improved by heat or mechanical processing as was indicated by this study.

The zebrafish BMP4 gene: sequence analysis and expression pattern during embryonic development

We have isolated zebrafish BMP4 gene from a zebrafish genomic DNA library. The size of the isolated BMP4 gene was approximately 14.9 kb. The isolated gene contained two exons which formed the complete coding region together with part of the 3'-noncoding region. The deduced BMP4 protein sequence contained 400 amino acids. Sequence comparison showed that it shared 73% amino acid sequence identity with that of human and mouse BMP4. An intron with a size of 8,963 bp was present between two coding exons. Danio retroposon A (DANA)-like retroposon was located in the intron. It contained four conserved boxes and was flanked by a pair of direct repeats of 9 nucleotide sequence (GTTTTAATA). During embryonic development of the zebrafish, a 3.8-kb BMP4 mRNA was detected from gastrula stage up to a month-old hatching larvae via Northern blot analysis. In addition, the use of reverse transcription polymerase chain reaction further demonstrated the presence of BMP4 mRNA in both the early developmental stages (i.e., cleavage and blastula) and in adult fish. Developmental expression of BMP4 protein was also analyzed. Trace amounts of an 18-kD protein were detected at pharyngula stage, while the production increased from hatching larvae to adult fish. In adult fish, the expression of BMP4 mRNA was observed in brain, heart, digestive tracts, testes, and jaw. The results suggest that the zebrafish BMP4 gene may play important roles during zebrafish development.

The signal response of IkappaB alpha is regulated by transferable N- and C-terminal domains

IkappaB alpha retains the transcription factor NF-kappaB in the cytoplasm, thus inhibiting its function. Various stimuli inactivate IkappaB alpha by triggering phosphorylation of the N-terminal residues Ser32 and Ser36. Phosphorylation of both serines is demonstrated directly by phosphopeptide mapping utilizing calpain protease, which cuts approximately 60 residues from the N terminus, and by analysis of mutants lacking one or both serine residues. Phosphorylation is followed by rapid proteolysis, and the liberated NF-kappaB translocates to the nucleus, where it activates transcription of its target genes. Transfer of the N-terminal domain of IkappaB alpha to the ankyrin domain of the related oncoprotein Bcl-3 or to the unrelated protein glutathione S-transferase confers signal-induced phosphorylation on the resulting chimeric proteins. If the C-terminal domain of IkappaB alpha is transferred as well, the resulting chimeras exhibit both signal-induced phosphorylation and rapid proteolysis. Thus, the signal response of IkappaB alpha is controlled by transferable N-terminal and C-terminal domains.

Characterization of Rab3A, Rab3B and Rab3C: different biochemical properties and intracellular localization in bovine chromaffin cells

In this study we examined the biochemical properties and subcellular localization of Rab3A, Rab3B and Rab3C in bovine adrenal chromaffin cells. The Kd for guanosine 5'-[gamma-thio]triphosphate (GTP[S]) of the three Rab3 proteins was 15, 2700 and 204 nM for Rab3A, Rab3B and Rab3C respectively. The intrinsic GTPase activity of the three Rab3 proteins seemed similar and was increased approx. 3-fold by bovine chromaffin cell lysate. Truncation of the C-terminal 31 amino acid residues decreased the binding affinity for GTP[S] of the three Rab3 proteins. When the C-terminus of Rab3C was replaced with that of Rab3A, the binding affinity of Rab3C for GTP[S] was decreased, but the replacement did not affect the affinity of Rab3B for GTP[S]. Immunostaining experiments showed that Rab3A, Rab3B and Rab3C are localized separately within chromaffin cells. Anti-Rab3A and anti-Rab3C antibodies stained vesicle-like structures, whereas anti-Rab3B antibody distinctly stained the plasma membrane. In summary, bovine chromaffin cells express the three Rab3 proteins but the subcellular localization and biochemical properties of the three Rab3 proteins are distinct.

Activation of complement and neutrophils increases vascular permeability during air embolism

Pulmonary air embolism occurs in diving and aviation during acute pressure reductions and in clinical complications. Undoubtedly physical obstructions play a role, but bubbles in blood can produce a number of indirect effects leading to tissue injury. In the present study, we investigated the involvement of the complement system and polymorphonuclear leukocytes (PMN) in altering segmental vascular resistance, lung weight gain, and filtration coefficient (Kf), by using isolated and perfused rat lungs. After establishing ventilation with air and 5% CO2, the lung was removed en bloc and suspended in a humidified chamber at 37 degrees C. Lung weight and arterial and venous pressures were monitored continuously. The buffered salt perfusate contains 4% Ficoll for osmotic balance. We used four series of perfusates containing 20% of: a) normal plasma; b) decomplemented plasma (from donor rats pretreated with a cobra venom factor); c) normal plasma and PMN at 2 x 10(6).ml-1; and d) decomplemented plasma and PMN at 2 x 10(6).ml-1. Pulmonary air embolism, air bubbles introduced through the pulmonary artery, increased pulmonary arterial resistance and pulmonary arterial blood pressure. The lung weight and lung water content were greater than those in the control groups. Air embolism increased vascular permeability, which was shown by an elevated Kf after air infusion. After air embolism, Kf was 0.63 +/- 0.05 g.min-1.cm H2O-1.100 g-1 in lungs perfused with both PMN and plasma, which was significantly greater than those in lungs perfused with either plasma (0.49 +/- 0.04), decomplemented plasma (0.44 +/- 0.03), or PMN and decomplemented plasma (0.47 +/- 0.03). These results demonstrated that air embolism increases vascular permeability of the lung by pulmonary hypertension, activation of the complement, and activation of PMN.

[An exploration of sexual knowledge, attitudes and behavior in aboriginal elementary school students in the Ping-Tung area]

The purpose of this study was to investigate sexual knowledge, attitudes and behavior of fifth and sixth grade students in aboriginal elementary schools in the Ping-Tung area. A structured questionnaire was administered to 1091 students who were selected by cluster sampling. The results showed: (1) The sexual knowledge score was low but sexual attitudes showed a positive trend. (2) 64.7% and 67.4% of students had at some time seen pictures of male or female sexual organs. (3) About 61% of students had seen sexual magazines or videotapes. (4) 66.2% of male and 88.1% of female students had heard about wet dreams or menstruation before their first experience; more than half of the students thought that wet dreams need treatment. (5) 17.8% of students had masturbation experience, and after that 59.3% of students had fear or guilt feeling. (6) Female students had significantly higher knowledge and attitude scores than male students, Demographic variables produced no significant difference in the above scores. (7) 42.4% of students most desired to know what phenomena indicate sexual maturity. (8) Sex knowledge had significantly positive correlation with sex attitude.

Gossypol arrests human benign prostatic hyperplastic cell growth at G0/G1 phase of the cell cycle

Recently we demonstrated that gossypol (GP), a male antifertility agent, is a potent inhibitor of malignant human prostate cancer cell growth that acts by arresting cells in G0/G1 phase and that this inhibitory effect may be mediated by transforming growth factor-beta 1 (TGF-beta 1). In this study we examined the effect of GP on the growth of prostatic cells from human benign prostatic hyperplasia (BPH) patients in vitro. Consistent with its inhibitory effect on the growth of malignant human prostate cancer cells, GP also acts as a potent inhibitor of cultured human BPH cell growth as assessed by thymidine incorporation assay. These results were confirmed by flow cytometric analysis which revealed that treatment of human BPH cells with increasing concentrations of GP resulted in a dose-dependent accumulation of cells in the G0/G1 phase with a concomitant decrease in cells progressing to the S and G2/M phases. Since inhibition of prostate cancer cells by GP appears to be mediated by TGF-beta 1, we also investigated the effect of GP on TGF-beta 1 gene expression in BPH cells. The results show that GP treatment resulted in a marked elevation of TGF-beta 1 gene expression indicating that TGF-beta 1 might be involved at least in part in the inhibitory pathway that is initiated by GP.

Inhibition of xanthine oxidase by synthetic cytokinin analogues

Thirteen synthetic cytokinin analogues were tested for their inhibitory effects on xanthine oxidase. The enzyme, xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and of xanthine to uric acid, which has a gamma max of 295 nm, forming the basis for a spectrophotometric assay of the activity of xanthine oxidase. The results showed that 8-azaadenine(1), 4-amino-6-hydroxypyrazolo [3,4-d] pyrimidine(4), 4-amino-6-mercaptopyrazolo [3,4-d] pyrimidine(5) and 4-aminopyrazolo [3,4-d] pyrimidine(6) display inhibitory effects on xanthine oxidase with an order of activity of IC50 = 0.54, 5.91, 8.17 and 25.46 microM, respectively. Their apparent inhibition constants (Ki) were 0.66, 1.54, 6.61 and 26.79 microM, and induced mixed(competitive-non-competitive), competitive, mixed (competitive-non-competitive), and competitive types of inhibition respectively, with respect to the substrate xanthine.

Gossypol induces spermidine/spermine N1-acetyltransferase in canine prostate epithelial cells

Gossypol is an antisteroidogenic compound naturally found in cottonseed. Gossypol has been shown to inhibit steroidogenesis in the canine prostate and may inhibit canine prostate growth. Its mechanism of action, however, is largely unknown. Our laboratory has previously demonstrated that in vivo administration of gossypol to male dogs can reduce circulating levels of testosterone and estradiol. Gossypol also showed an ability to reduce prostate weights. To search for genes regulated by gossypol in the canine prostate, differential display RT-PCR was performed on total RNAs isolated from control and gossypol-treated male dogs. Gossypol was demonstrated to induce expression of spermidine/spermine-N1-acetyl-transferase (SSAT), the major catabolic enzyme for polyamines. This induction was confirmed by Northern hybridization analysis of total RNA isolated from prostates of mature dogs treated with gossypol for 2 months. Gossypol was also shown to inhibit the progression of cells into the S phase mediated by spermidine. Our findings support the notion that gossypol can inhibit prostate cell proliferation and may be a potential therapeutic agent for use in controlling overgrowth of the prostate.