Androgen receptor content of the normal and hyperplastic canine prostate.

A procedure was developed for measurement of androgen receptors in cytoplasmic extracts of prostates from intact dogs. The protocol utilized exchange saturation analysis at 15 degrees C employing the synthetic androgen R1881 (17beta-hydroxy-17alpha-methylestra-4,9,11-trien-3-one) as the ligand probe and quantitatively detected total cytoplasmic androgen receptor (R(c), androgen-free receptor, and R(c)A, androgen-occupied receptor) present at the initiation of the assay. This protocol was employed in conjunction with a tissue mince saturation analysis procedure (for quantitation of nuclear androgen receptor) to quantitate total androgen receptor content of normal and hyperplastic prostates obtained from young (2.5- or 4.6-yr old) and aged (12.5-yr old) purebred dogs of known birth date. The total cytoplasmic androgen receptor content (picomoles per prostate) of hyperplastic prostates was 4.6-fold greater than that of normal prostates. The total nuclear androgen receptor content of hyperplastic prostates (picomoles per prostate measured in crude nuclear preparations) was either 5.0- (4.6-yr-old dogs) or 7.8-fold (2.5-yr-old dogs) greater than that of normal prostates. However, androgen receptor content per cell was identical for hyperplastic and normal canine prostates, with the exception that nuclear androgen receptor was diminished in prostates from 2.5-yr-old dogs. The cell content per gram dry weight was identical for hyperplastic and normal canine prostates. We conclude that canine prostate hyperplasia is characterized by coordinate proliferation of androgen receptor-positive and androgen receptor-negative cells and is not a consequence of increased accumulation of 5alpha-dihydrotestosterone due to proliferation of androgen receptors per prostate cell.

Spontaneous adenocarcinomas of the ventral prostate of aged A X C rats.

Spontaneous adenocarcinomas of the ventral prostate were present in 7 of 41 aged (34- to 37-month-old), virgin, untreated male A X C rats. The only consistent gross evidence of possible neoplastic involvement was intraprostate hemorrhage. The principally intraglandular neoplasms were composed of markedly anaplastic epithelial cells which retained a moderate propensity to form glandular patterns. The nuclei of the neoplastic cells were pleomorphic, vesiculated, enlarged, and hyperchromatic. Mitotic figures were frequent. Interglandular connective tissue was invaded in one rat; however, metastases were not demonstrated.

C19-steroid metabolism by spontaneous adenocarcinoma of the A X C rat ventral prostate.

Specimens of ventral prostate from 37- to 46-month-old Andradurin-treated A X C rats demonstrated three primary morphologic patterns, each being divisible into two sub-groups based upon the extent of glandular alteration. The principal groups were: group 1, hyperplasia; group 2, atypical hyperplasia; and group 3, adenocarcinoma. The secondary classifications were: subgroup (+), few glands involved; and subgroup (++), most glands involved. Multiple parameters of ventral prostate testosterone metabolic potential failed to distinguish the morphologically diverse prostate specimens of groups (1+). 1(++), 2(+), 2(++), and 3(+) which predominantly metabolized testosterone to 5alpha-reduced 17beta-hydroxysteroids. By contrast, testosterone metabolism by ventral prostate specimens predominantly composed of neoplastic epithelium, group 3(++), was distinct from all other prostate specimens. The distinguishing feature was a shift to more prominent elaboration of 17-ketosteroids, principally delta4-androstenedione, and a cteroids. The change in this biochemical parameter of prostate epithelial cell function was indicated to be an early manifestation of the neoplastic transformation.

A x C rat prostate adenocarcinoma: initial characterization of testosterone regulation of hormone receptors of cultured cancer cells and derived tumors.

A x C rat prostate cancer cells were established in continuous culture. The polygonal epithelial cells had granular cytoplasm and well-defined cell margins, contained round to oval nuclei with prominent nucleoli, and were tumorigenic when inoculated into A x C male rats. The tumors produced by the injected prostate cancer cells grew as well-vascularized, solid, cribriform adenocarcinomas. The rat prostate cancer cells and derived tumors contained cytoplasmic and nuclear androgen receptors and prolactin receptors. Androgen regulation of prolactin receptor content and androgen receptor distribution in A x C rat prostate cancer cells were comparable to those of the normal ventral prostate gland. These studies suggest that the A x C rat prostate cancer cells and tumors may represent a unique model for studies of hormonal regulation of prostate cancer cell behavior.

Oncorna-like viruses in baboon prostate tissue.

Oncorna-like virus particles were observed in prostate tissue of 2 of 11 baboons inoculated 3 years previously with a chemical carcinogen. There were no indications, however, of any relationship between the carcinogen and the development of virus particles. Biopsy specimens from the animals showed no evidence of neoplasia, and electron microscopic examination suggested that this virus should be categorized as a B-type oncornavirus.

Differential androgen modulation of AXC/SSh rat prostate cancer cell proliferation in vitro and its antagonism by antiandrogen.

We examined androgen modulation of proliferation of clonally derived AXC/SSh rat prostate cancer cells. C-family cells were maintained on medium without addition of androgens. D-family cells were maintained on medium containing 10(-7) M 5 alpha-dihydrotestosterone and T-family cells were maintained on medium containing 10(-7) M testosterone. Proliferation of all AXC/SSh prostate cancer cell lines during propagation on media containing fetal bovine serum was not altered by changes in media testosterone concentration through the range 10(-6) to 10(-9) M. Similarly, proliferation of C- or D-family cell lines, during propagation on media containing steroid depleted, charcoal stripped fetal bovine serum, was not altered by changes in media testosterone concentration through the range 10(-6) to 10(-9) M. By contrast, proliferation of T-family cell lines during propagation on charcoal stripped fetal bovine serum was modulated by androgens; effects were androgen concentration dependent and maximum at 10(-8) to 10(-7) M. Androgens decreased T5 cell proliferation rate and diminished achievable saturation density, whereas T1 cell proliferation rate was increased by androgens. In contrast, T6 cell proliferation rate was unaffected by androgens; however, saturation density was increased. Effects were antagonized by the antiandrogen RU 23908, Anandron, establishing androgen specificity of testosterone or 5 alpha-dihydrotestosterone mediated changes in proliferation.

Differences in responsiveness of clonally derived AXC/SSh rat prostate cancer cells to secreted or prototypic mitogens.

AXC/SSh rat prostate cancer cells elaborate heat-sensitive, heparin-binding mitogens which include members of the fibroblast growth factor (FGF)-like family of growth factors. The quantity of FGF-like growth factors, relative to total growth factor production, was cell line specific as was prostate cancer cell response to secreted or the prototypic mitogens basic FGF (bFGF), acidic FGF (aFGF), or epidermal growth factor (EGF). C3 cell proliferation, assayed either by cell counting or thymidine incorporation, was not affected by mitogens secreted by C3, D1, T1, or T5 prostate cancer cells or by bFGF, aFGF, or EGF. In contrast, C3, D1, T1, or T5 cell-secreted mitogens enhanced proliferation of T1 and T5 cells, and proliferation of D1, T1, and T5 cells was enhanced by bFGF, aFGF, and EGF. D1 cell response to prototypic mitogens was 3- to 12-fold less than that of T1 or T5 cells. By comparison, the NRKF cell response to prototypic mitogens was qualitatively comparable but quantitatively greater than that of rat prostate cancer cells. The relative and absolute bFGF or aFGF concentrations necessary for half-maximum stimulation of prostate cancer or normal rat kidney fibroblast cell thymidine incorporation were comparable to that known to effect half-maximum increase in proliferation of mesoderm-derived cells. Similarly, the EGF concentration required for half-maximum prostate cancer or normal rat kidney fibroblast cell thymidine incorporation was comparable to that known to effect half-maximum fibroblast thymidine incorporation or granulosa cell proliferation. Our data establish that prostate cancer cell response to prototypic mitogens is representative of that of nonneoplastic cells and imply that C3 cell insensitivity to prostate cancer cell or prototypic mitogens represents defects in cellular response mechanisms. The basis for C3 cell unresponsiveness or D1 cell-diminished responsiveness remains to be elaborated.

Biochemical and morphological characterization of clonal AXC rat prostate cancer cells.

We used three heterogeneous parental cultures of LSC-AXC rat prostate cancer cells: LSC-AXC-C/O, cells maintained on culture medium; LSC-AXC-D/O, cells maintained on culture medium containing 10(-7) M 5 alpha-dihydrotestosterone; and LSC-AXC-T/O, cells maintained on culture medium containing 10(-7) M testosterone, to isolate clonally derived cell lines. Eleven of 15 clonal cell lines were tumorigenic when inoculated into intact male AXC rats. Eight tumorigenic clonal cell lines were selected for further evaluation, and all were found to possess features characteristic of secretory epithelium, as judged by light and electron microscopy. All parental cell lines and the eight selected clonal cell lines contained cytoplasmic and nuclear androgen receptors. Total receptor content was 131 +/- 61 (S.D.), 43 +/- 32, and 274 +/- 96 fmol/100 micrograms of DNA, respectively, for C-, D-, and T-cells. The differences were significant (p less than 0.05). Androgen receptor content of young mature or senescent AXC rat ventral prostate, respectively, is 518 +/- 58 and 266 +/- 40 fmol/100 micrograms of DNA. Since chromosomal analysis established that LSC-AXC prostate cancer cells are hypotriploid, androgen receptor content per cell in C- and T-cells is indicated to be either greater than or equal to that of senescent AXC rat ventral prostate, the tissue in which the original adenocarcinoma arose. Parental and clonal cell lines contained 5 alpha-reductase activity. There were significant differences (p less than 0.05) in both total reductase activity and metabolite distribution. Consequently, the intracellular content of testosterone metabolites was cell line specific. All characterized cell lines contained a higher concentration (p less than 0.05) of APase activity than did young mature or senescent AXC rat ventral prostate. In 6 of 11 cell lines, prostate-secretory APase concentration exceeded (p less than 0.05) that of AXC rat ventral prostate. However, the relative content of secretory APase compared to total APase in carcinoma cells consistently was less (p less than 0.05) than that of AXC rat ventral prostate. These studies document the establishment of clonal AXC rat prostate adenocarcinoma cell lines which have retained important morphological and phenotypic markers characteristic of differentiated prostate epithelium. Since these cells are tumorigenic and represent a spectrum of retained differentiated phenotypic markers, they should be particularly useful for in vivo and in vitro studies of hormonal regulation of prostate cancer cell behavior.

Human prostate androgen receptor quantitation: effects of temperature on assay parameters.

When cytoplasmic extracts of human prostatic tissues were split to permit quantitation of total androgen receptor (RCT) content by saturation analysis at 15 degrees and 2 degrees, we observed that 30% (10 of 32) of the specimens yielded statistically increased values for RCT following incubation at 15 degrees as compared to 2 degrees. Considering only those specimens (13 of 32) showing statistically differentiated RCT yield, 77% (10 of 13) yielded greater RCT content following incubation at 15 degrees. The families of association constants (Ka) obtained for RCT determinations at 2 degrees and 15 degrees were not statistically differentiated. The increased yield of RCT content determined at 15 degrees was 95% (mean) and 20 to 350% (range). Nuclear androgen receptor content determined at 15 degrees was greater for 25% (2 of 8) of the patient specimens when compared to split determinations performed at 2 degrees. Incubation of nuclear extracts at 15 degrees resulted in a significant 3-fold reduction in receptor Ka for methyltrienolone (R1881). This did not appear to affect assay precision. These studies showed that incubation at 15 degrees is preferable to incubation at 2 degrees for quantitation of RCT and nuclear androgen receptor content by saturation analysis. Single saturating dose determinations of RCT consistently yielded underestimates. The extent of underestimate was variable from specimen to specimen and was both ligand concentration and assay temperature dependent. Our data suggest that results of single saturating dose determinations of RCT require cautious interpretation.

Inability of cytoplasmic or nuclear androgen receptor content or distribution to distinguish benign from carcinomatous human prostate.

We used exchange saturation analysis at 15 degrees to quantitate total cytoplasmic and nuclear androgen receptor content of 70 patient specimens. Cytoplasmic androgen receptor contents (fmol/mg DNA) for eight specimens of clinically benign hyperplasia, 14 specimens of histologically hyperplastic prostate obtained at cystoprostatectomy, and carcinomatous and noncarcinomatous prostate obtained at radical prostatectomy for prostatic carcinoma, 48 specimens, respectively, were 830 +/- 165 (mean +/- S.E.), 890 +/- 445, 955 +/- 240, and 750 +/- 95. Nuclear androgen receptor contents of these same specimens, respectively, were 275 +/- 40, 235 +/- 30, 345 +/- 25, and 350 +/- 30; whereas, the values of the cytoplasmic/nuclear receptor content, respectively, were 3.25 +/- 0.55, 3.05 +/- 0.80, 2.50 +/- 0.50, and 2.80 +/- 0.40. Multiway analyses of variance of these cross-sectional data showed that there was no significant difference (p greater than 0.05) between group mean values. This result principally reflects the fact that the families of values for the four tissue groups were highly heterogenous with broad overlap. The results would not appear to be unduly influenced by carcinomatous epithelial cell content of the specimens, because cytoplasmic and nuclear androgen receptor content were not related to specimen carcinomatous epithelial cell content. Paired analyses of receptor content in carcinomatous and noncarcinomatous prostate specimens from the same prostate showed enhanced or unchanged receptor content in 58% (cytoplasmic) and 62% (nuclear) of specimens. Our studies show that cross-sectional analyses of androgen receptor content fail to distinguish carcinomatous prostate from noncarcinomatous prostate. However, paired analyses of these tissues from the same gland identify distinguishing differences. The clinical relevance of these observations remains to be examined.

Sexual dimorphism characterizes steroid hormone modulation of rat aortic steroid hormone receptors.

Quantification of aortic androgen and estrogen receptor content and distribution in AXC/SSh rats established that the total androgen receptor content in intact young mature males (mean +/- SD, 55 +/- 13 fmol/mg DNA) was indistinguishable (P greater than 0.05) from that in proestrous females (50 +/- 3 fmol/mg DNA). However, 60% of male aortic androgen receptors were in the nuclear fraction, whereas all proestrous female aortic androgen receptors were in the cytoplasmic fraction. The total aortic estrogen receptor content of intact young mature males (70 +/- 16 fmol/mg DNA) was indistinguishable (P greater than 0.05) from that of proestrous (92 +/- 12) or diestrous (77 +/- 4) females. However, 50% of proestrous female aortic estrogen receptors were in the nuclear fraction, whereas male or diestrous female aortic estrogen receptors were restricted to the cytoplasmic fraction. To assess estrogen receptor function, we characterized aortic cytoplasmic progesterone receptors and established that the receptor content of intact male aortae (101 +/- 3 fmol/mg DNA) was not significantly different (P greater than 0.05) from that of diestrous female aortae (100 +/- 11). 17 beta-Estradiol injection of intact males failed to affect aortic progesterone receptor content (93 +/- 17 fmol/mg DNA). However, injection of orchiectomized males with 17 beta-estradiol significantly (P less than 0.05) increased progesterone receptor content to 208 +/- 24 fmol/mg DNA. This value is twice that of intact males and is not significantly different (P greater than 0.05) from the aortic cytoplasmic progesterone receptor content (190 +/- 32 fmol/mg DNA) of 17 beta-estradiol-injected oophorectomized females. These studies establish that intracellular distribution of aortic androgen and estrogen receptors of male or female AXC/SSh rats is regulated by endogenous hormones. The observation that 17 beta-estradiol modulates aortic progesterone receptor content indicates that rat aortic estrogen receptors are physiologically functional. Our data imply that steroid hormones directly regulate aspects of rat cardiovascular cell function and that sexually dimorphic differential regulation may characterize male and female aortic metabolism.

Aging in the AXC rat: differential effects of chronic testosterone treatment on restoration of diminished prostate L-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase activities.

L-Ornithine decarboxylase (ODC) activity per 100 mg prostate was diminished 88% and S-adenosyl-L-methionine decarboxylase (AMDC) activity similarly ws diminished 57% in the ventral prostate of aged (26-month-old) as compared to that of young (3.8-month-old) AXC rats. Dorsolateral prostate ODC activity was too low to be reliably quantitated. Dorsolateral prostate AMDC activity per 100 mg prostate was diminished 55% in aged AXC rats. The age-related declines in prostate ODC and AMDC were not attributable to changes in the properties of the enzymes in aged AXC rats compared to young rats. There also was no evidence for an age-related production of inhibitors or inactivators of these prostate enzymes. The sensitivities of prostate ODC and AMDC to orchiectomy were comparable in young and aged AXC rats. Treatment of aged AXC rats with exogenous testosterone did not enhance ventral prostate AMDC activity per 100 micrograms DNA, but it did elevate dorsolateral prostate AMDC activity per 100 micrograms DNA to levels indistinguishable from those characteristic of untreated young AXC rats and caused a 303% increase in ventral prostate ODC activity per 100 micrograms DNA. However, ODC activity per 100 micrograms DNA in the ventral prostate of testosterone-treated aged rats was only 49% of that characteristic of untreated young AXC rats. We have identified three categories of age-related changes in prostatic enzyme activity: 1) decline fully reversible by exogenous testosterone, 2) decline partially reversible by exogenous testosterone, and 3) decline not reversible by exogenous testosterone. These alterations may reflect age-related changes in androgen-regulated prostate gene function.

Aging in the AXC rat: equivalence of the rates of inactivation of l-ornithine decarboxylase and S-adenosyl-L-methionine decarboxylase in prostate of young and aged rats.

The incorporation of leucine into proteins of ventral and dorsolateral prostates of young (3- to 4-month-old) and aged (24- to 26-month-old) AXC rats was examined in vivo. We established that a single injection of cycloheximide (500 micrograms/100 g BW) maintained 91% (ventral) or 86% (dorsolateral) inhibition of protein synthesis in prostates of young AXC rats and 90% (ventral) or 88% (dorsolateral) inhibition of protein synthesis in prostates of aged AXC rats through at least 120 min post injection. During cycloheximide-maintained inhibition of protein synthesis, the rate of inactivation of ventral prostate L-ornithine decarboxylase (ODC) or S-adenosyl-L-methionine decarboxylase (AMDC) activity and dorsolateral prostate AMDC activity was comparable in the prostates of young and aged AXC rats. The absence of an age-related change in the rate of inactivation of prostatic ODC or AMDC activity provides additional evidence that the age-related decrease in prostatic ODC and AMDC activities reported in the companion article may reflect altered androgen regulation of prostatic gene activity.

Effect of aging on AXC/SSh rat ventral and dorsolateral prostate S-adenosyl-L-methionine decarboxylase and L-ornithine decarboxylase messenger ribonucleic acid content.

Ventral prostate S-adenosyl-L-methionine decarboxylase (AMDC) and L-ornithine decarboxylase (ODC) transcript content decreased 5-fold as males aged from 6 to 26 months. In contrast, dorsolateral prostate AMDC and ODC transcript content in these individuals was age invariant. The differential effect of aging on tissue transcript levels reflected respective 3.5- and 5-fold decreases in ventral prostate total and poly(A)+ RNA content in aging males, whereas dorsolateral prostate RNA levels essentially were age invariant. Testosterone injection of 26-month-old males increased ventral and dorsolateral prostate content of AMDC and ODC transcripts 4- and 2.5-fold, respectively. Changes in ventral prostate ODC transcript levels correlated well with previously reported age- and testosterone-mediated changes in prostate ODC protein content; however, the relation between ventral or dorsolateral prostate AMDC mRNA levels and previously determined AMDC protein content was less stringent. Our observation that ventral prostate ODC transcript content was 7-fold greater than that of dorsolateral prostate was insufficient to account for the established 200-fold difference in ODC activity in these tissues. Our data imply that transcript content is a principal determinant of ventral prostate ODC activity in aging AXC/SSh rats. However, this relationship does not appear to characterize either ventral or dorsolateral prostate AMDC activity or relative ventral and dorsolateral prostate ODC activity and transcript content. The cause of the age-related preferential loss of ventral prostate RNA remains to be evaluated.

Aging in the AXC rat: diminished prostatic S-adenosyl-L-methionine decarboxylase (AMDC) activity appears to reflect altered expression of the AMDC gene.

We purified AXC rat hepatic S-adenosyl-L-methionine decarboxylase (AMDC) 4900-fold and obtained a preparation that was 75% AMDC. This material caused elaboration of rabbit antirat AMDC antibodies that essentially were monoprecipitating. Antibody from one rabbit was highly effective as an inactivator of prostatic AMDC activity and was used to evaluate the quantitative relationship between antigenic mass and AMDC activity in ventral and dorsolateral prostates of young mature (185-day-old) and aged (776-day-old) AXC rats. Although AMDC activity of aged AXC rat prostates was diminished (ventral, 68%; dorsolateral, 50%), the quantities of antibody required to inactivate 1 U AMDC activity in prostates of young mature and aged rats were identical. This antibody effectively recognized enzymatically inactive AMDC, which is antigenically similar to active AMDC. Therefore, the age-related reductions in prostatic AMDC activity are not due to the production of so-called altered AMDC. Four days of exogenous testosterone treatment of aged AXC rats failed to enhance ventral prostate AMDC activity, whereas AMDC activity in dorsolateral prostates was elevated 2.3-fold. New AMDC activity was antigenically identical to that in dorsolateral prostates of untreated young mature or aged AXC rats. Because we previously established that age-related reductions in AXC rat prostatic AMDC activity are due to neither trivial causes nor enhanced inactivation, our present studies imply that reductions in AMDC activity are due to decreased prostatic AMDC content. These studies are an initial demonstration of senescence-related quantitative reductions in the prostatic content of AMDC molecules, which appear to represent altered expression of a specific androgen-responsive prostatic gene.

Aging in the AXC/SSh rat: diminished prostate L-ornithine decarboxylase (ODC) activity reflects diminished prostate ODC protein and transcript content.

Immunotitration of L-ornithine decarboxylase (ODC) activity in ventral prostates of young mature (6-month-old) and aged (26-month-old) AXC/SSh rats established that the relation between enzyme activity and prostate ODC mass content was age invariant, demonstrating that the 4-fold diminution in prostate ODC activity in aged subjects represents decreased ODC protein content. Testosterone treatment of aged rats increased prostate ODC activity 2-fold and did not affect prostate ODC half-life. These latter findings and the preceding observation established that the testosterone-mediated increase in prostate ODC activity in aged individuals reflected increased ODC mass content. The half-life of prostate S-adenosyl-L-methionine decarboxylase, another prominent enzyme of polyamine biosynthesis, also was not altered by testosterone treatment of 26-month-old animals. The age-related diminution and testosterone-mediated increase in ventral prostate ODC activity occurred in concert with comparable quantitative changes in ventral prostate ODC transcript content. Because plasma testosterone content was age invariant between 3 and 18 months, the age span during which much of the reduction in prostate ODC activity occurs, and then declined by 50% at 26 months, our studies suggest that age-related diminutions in prostate ODC activity and transcript content reflect altered prostate sensitivity to androgen rather than response to diminished plasma testosterone content. Our data imply that age-related alterations in androgen regulation of androgen-responsive genes may be characteristic of the prostate during aging.

Rat prostate cancer cells contain functional receptors for transforming growth factor-beta.

Clonally derived C-, D-, and T-family AXC/SSh rat prostate cancer cell lines contain transforming growth factor-beta (TGF beta) receptors. The content in C3, D1, T1, and T5 cells, respectively, was 8,560 +/- 1,450, 13,160 +/- 1,240, 2,425 +/- 490, and 10,540 +/- 1,025 sites/cell (mean +/- SEM). Respective Kd values were 160 +/- 48, 200 +/- 53, 24 +/- 3, and 115 +/- 15 pM (mean +/- SEM). T1 cell TGF beta receptor site content and Kd differed significantly from those of other prostate cancer cell lines (P less than 0.05). TGF beta is a bifunctional concentration-dependent modulator of T1 and T5 cell thymidine incorporation. At low concentrations, thymidine incorporation was inhibited, whereas as the medium TGF beta content was increased, T1 and T5 cell thymidine incorporation was stimulated. The concentrations of TGF beta causing half-maximum inhibition of T1 or T5 cell thymidine incorporation, respectively, were 0.11 and 0.24 pM, whereas the respective TGF beta concentrations causing half-maximum stimulation of thymidine incorporation were 14.4 and 134 pM. These findings establish that rat prostate cancer cell sensitivity to TGF beta inhibition of function is at least 2 orders of magnitude greater than that of most other mammalian cells. In contrast, the sensitivity of rat prostate cancer cells to TGF beta enhancement of function is comparable to that of other mammalian cells. TGF beta inhibited basic fibroblast growth factor (bFGF) stimulation of T1 and T5 cell thymidine incorporation. Because the concentration of bFGF required for half-maximum increase of T5 cell thymidine incorporation was independent of medium TGF beta content, the effect of TGF beta is distal to the T5 cell bFGF receptor. In contrast, the concentration of bFGF required for half-maximum increase in T1 cell thymidine incorporation increased 5-fold as the medium TGF beta content was increased; suggesting that the effect of TGF beta in T1 cells is proximal to the T1 cell bFGF receptor. Our studies establish that rat prostate cancer cells contain functional TGF beta receptors, imply the presence of functional bFGF receptors, and demonstrate that mitogen modulation of prostate cancer cell function is multifactorial. The finding that TGF beta is a bifunctional effector of prostate cancer cell DNA synthesis provides some insight into the potential complexity of mitogen modulation of prostate cancer cell proliferation. The mechanism by which these mitogens interact is unknown; however, our studies suggest that some interactive effects may be cell line specific.

Testosterone metabolism by the prostate of the aging canine.

Examination of testosterone metabolism in the dorsal, lateral, and ventral regions of the beagle prostate showed an absence of regional heterogeneity for testosterone metabolite production and metabolic capacity. Testosterone metabolism by the hyperplastic prostate of aged beagles (11.1 years old) was distinguished from that of young mature (2.5-year-old) and mature adult (4.5-year-old) beagle prostate by increased reductive metabolism. The change was principally the consequence of increased production of 5 alpha-dihydrotestosterone and decreased production of 4-androstenedione. These alterations in testosterone metabolism occurred progressively and may be weakly linked to other changes in canine prostate which occur during aging. 5 alpha-Androstane-3 alpha, 17 beta-diol production was maximal for prostate from 4.5-year-old beagles and the amount of this metabolite produced appeared to be unrelated to prostate size. Co-incubation of prostate from any of the beagles with testosterone and estradiol showed that estradiol had no in vitro effect upon testosterone metabolism. Mean plasma testosterone content of aged beagles (11.1 years old) was not significantly different from that of younger individuals; however, the heterogeneity of the values for the subject groups was notable. The data demonstrate that the consequences of aging upon testosterone metabolism by canine prostate, which principally develops benign prostatic hyperplasia, are opposite to those characteristic of senescent rat prostate, which does not develop bening prostatic hyperplasia and has a high incidence of spontaneous adenocarcinoma.

Testosterone metabolism by the prostate of the aging AXC rat.

Testosterone metabolism by the ventral prostate of inbred, senescent (36-month-old) AXC rats showed a shift to increased oxidative and diminished reductive metabolism when compared to young mature (3-month-old) or mature adult (6-month-old) AXC rats. The change was principally attributable to diminished production of 5 alpha-dihydrotestosterone and increased production of 4-androstenedione. By contrast, dorsolateral prostate testosterone metabolism in these same rats was always more reductive than that of ventral prostate and failed to show the post-maturation shift to oxidative testosterone metabolism which characterized ventral prostate. Co-incubation of either ventral or dorsolateral prostate from any of these rats with testosterone and estradiol showed that estradiol did not significantly affect prostate testosterone metabolism. Plasma testosterone content of senescent AXC rats was only 28% of that of mature adult rats. Chronic exogenous testosterone treatment enhanced reductive testosterone metabolism by ventral prostate and eliminated those changes in metabolite distribution which had differentiated testosterone metabolism by young and senescent AXC rats. The data support the interpretation that the aging-related diminution in AXC rat ventral prostate reductive metabolic capacity is primarily the consequence of diminished 5 alpha-dihydrotestosterone production secondary to diminished plasma testosterone content.

Aging in the AXC/SSh rat: characterization of moderately abundant ventral prostate proteins showing age-dependent diminution and one protein exhibiting age-invariant content.

To determine whether prior demonstrations of age-related decrements in prostate content of minor, androgen regulated proteins represent a generalized phenomenon, we validated a denaturing polyacrylamide gel electrophoretic protocol for separation and quantification of moderately abundant ventral prostate cytoplasmic proteins. We established age-related, progressive 3- to 3.5-fold decreases in prostate content of proteins of 90, 79, 63, and 58 kDa and found that content of a 46 kDa protein was age-invariant. The amount of 90 and 46 kDa proteins was not significantly altered, whereas the level of 79, 63 and 58 kDa proteins decreased during 72 h post-orchiectomy of 3-month-old rats. Testosterone injection of intact 26-month-old rats caused an average 2-fold increase in 90, 79, 63, and 58 kDa protein content and did not affect 46 kDa protein level. Because we demonstrated the 46 kDa protein is not a secretory protein, absence of an affect of aging or testosterone on prostate content is not due to secretion mediated inaccessibility to intracellular processing. The apparent relation between age and prostate content of these proteins is not a consequence of potential age-related changes in ventral prostate cell content or distribution because biochemical and histologic analyses show this does not significantly occur. Our studies establish age-related decreases in ventral prostate content of moderately abundant, androgen responsive proteins and show that content of at least one protein is age- and androgen-independent. It remains to be determined whether these findings reflect direct effects of gene regulation.