Canine prostate carcinomas express markers of urothelial and prostatic differentiation

Prostate carcinoma and transitional cell carcinoma (TCC) occur in the prostate gland of older dogs and have morphologic similarities when evaluated by light microscopy. The dog is a commonly used animal model for studying human prostate carcinoma; therefore, it is important to accurately differentiate canine prostate carcinomas from TCCs. We investigated whether keratin 7 (K7) and arginine esterase (AE) would aid differentiation of canine prostate carcinoma from TCC. K7 expression was evaluated in normal and neoplastic canine prostate and bladder tissues using immunohistochemistry. The expression of AE messenger ribonucleic acid (mRNA) in normal and neoplastic canine prostate and bladder was detected using northern blots and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, AE enzyme activity was measured in normal and neoplastic canine prostate and bladder tissues. We found marked similarities in K7 expression in prostate carcinomas and TCCs. AE mRNA was present in high levels in normal prostatic tissue but was reduced in prostate carcinoma by northern blot assay. Nested RT-PCR detected AE mRNA both in TCCs (13 of 15) and in prostate carcinomas (13 of 13). Enzymatic activity of AE was high in normal prostate gland and in some prostate carcinomas, whereas normal bladder and TCCs produced lower levels of AE. In conclusion, K7 and AE cannot be used to differentiate TCC from prostate carcinoma in dogs.

Prostatic intraepithelial neoplasia in mice expressing an androgen receptor transgene in prostate epithelium

Prostate cancer (PCa) is an androgen dependent disease that can be treated by androgen ablation therapy, and clinical trials are under way to prevent PCa through the reduction of androgen receptor (AR) activity. However, there are no animal models of AR-mediated prostatic neoplasia, and it remains unclear whether the AR is a positive or negative regulator of cell growth in normal prostate secretory epithelium. To assess the direct effects of the AR in prostate epithelium, a murine AR transgene regulated by the rat probasin promoter (Pb) was used to generate transgenic mice expressing increased levels of AR protein in prostate secretory epithelium. The prostates in younger (<1 year) Pb-mAR transgenic mice were histologically normal, but Ki-67 immunostaining revealed marked increases in epithelial proliferation in ventral prostate and dorsolateral prostate. Older (>1 year) transgenic mice developed focal areas of intraepithelial neoplasia strongly resembling human high-grade prostatic intraepithelial neoplasia (PIN), a precursor to PCa. These results demonstrate that the AR is a positive regulator of cell growth in normal prostate epithelium and provide a model system of AR-stimulated PIN that can be used for assessing preventative hormonal therapies and for identifying secondary transforming events relevant to human PCa.

Role of canine basal cells in postnatal prostatic development, induction of hyperplasia, and sex hormone-stimulated growth; and the ductal origin of carcinoma

BACKGROUND

The canine prostate has often been proposed as a model for abnormal growth of the human gland. Hyperplasia of the prostate is common in aging men and has been estimated to be present in 100% of old intact dogs. While prostatic carcinoma is common in older men, it appears to be rare in dogs and unlike the disease in humans, it occurs with relatively high frequency in castrated animals. Since basal cells are thought to be key participants in normal and abnormal growth of the human gland, we used immunohistochemistry to investigate the role that they may play in canine prostatic development, the evolution of hyperplasia and carcinoma, and the effects of sex hormones on these cells.

METHODS

Prostate specimens were obtained at autopsy from seven sexually immature dogs, autopsy and biopsy samples from 14 sexually mature intact animals, from four castrates, and from19 dogs with prostatic carcinoma. In addition, we also studied the prostates from two intact dogs treated with 5alpha-dihydrotestosterone (DHT) for 6 months and two castrated dogs that were subsequently treated with 5alpha-androstane-3alpha diol and estradiol-17alpha, as well as specimens from two sexually ablated animals given DHT for 2 weeks. All specimens were immunostained for high molecular weight cytokeratin (HMC), pancytokeratin, androgen receptor (AR), and the proliferative marker KI-67.

RESULTS

We find that basal cells are the major proliferative cell type in the neonatal and adult canine prostate and that the expression of HMC staining, which defines these cells, may be regulated by androgens. In the adult gland, ductal basal cells formed a contiguous layer, whereas those lining acini were discontinuous. Populations of both basal cell types were variably AR positive, but while HMC immunostaining was abolished in acinar cells following long-term castration, staining remained in ductal cell counterparts. Paralleling the histological development of hyperplasia, the acinar basal cell population increased with age and were the major cell type that expressed KI-67. In contrast, ductal basal cell populations did not expand in the prostates of older dogs and were seldom positively stained for KI-67. The numbers of HMC and KI-67-stained acinar basal cells were dramatically increased in the prostates of intact dogs treated with DHT when compared with glands of untreated controls. This was not the case with ductal basal cells. Androgens given alone or together with estrogen to castrated dogs induced widespread HMC and KI-67 immunostaining in both populations of basal cells. In addition, our results indicate that the majority of canine prostatic carcinomas likely arise exclusively from ductal epithelium. Only one of the 19 cases of carcinoma contained cells that expressed AR, which suggests that androgens may not be required for the initiation or progression of these cancers.

CONCLUSIONS

Our findings indicate that two biologically distinct populations of basal cells may exist in the canine prostate. In this regard, the age-related expansion of proliferating acinar basal cell populations, probably mediated by sex steroids, is a key factor in the pathogenesis of canine prostatic hyperplasia. Additionally, we find that prostatic carcinoma in the dog likely arises from ductal cells. Taken together, these findings may indicate that canine acinar basal cells and ductal epithelium have separate susceptibilities to factors that promote hyperplastic or neoplastic development.

Role of canine basal cells in prostatic post natal development, induction of hyperplasia, sex hormone-stimulated growth; and the ductal origin of carcinoma

BACKGROUND

The canine prostate has often been proposed as a model for abnormal growth of the human gland. Hyperplasia of the prostate is common in aging men and has been estimated to be present in 100% of old intact dogs. While prostatic carcinoma is common in older men it appears to be rare in dogs and unlike the disease in humans it occurs with relatively high frequency in castrated animals. Since basal cells are thought to be key participants in normal and abnormal growth of the human gland, we used immunohistochemistry to investigate the role that they may play in canine prostatic development, the evolution of hyperplasia and carcinoma, and the effects of sex hormones on these cells.

METHODS

Prostate specimens were obtained at autopsy from seven sexually immature dogs, autopsy and biopsy samples from 14 sexually mature intact animals, from four castrates, and from 19 dogs with prostatic carcinoma. In addition, we also studied the prostates from two intact dogs treated with 5 alpha-dihydrotestosterone (DHT) for 6 months and two castrated dogs that were subsequently treated with 5 alpha-androstane-3 alpha diol and estradiol-17 alpha as well as specimens from two sexually ablated animals given DHT for 2 weeks. All specimens were immunostained for high molecular weight cytokeratin (HMC), Pancytokeratin, androgen receptor (AR), and the proliferative marker KI-67.

RESULTS

We find that basal cells are the major proliferative cell type in the neonatal and adult canine prostate and that the expression of HMC staining, which defines these cells, may be regulated by androgens. In the adult gland, ductal basal cells formed a contiguous layer whereas those lining acini were discontinuous. Populations of both basal cell types were variably AR positive but while HMC immunostaining was abolished in acinar cells following long-term castration, staining remained in ductal cell counterparts. Paralleling the histological development of hyperplasia, the acinar basal cell population increased with age and were the major cell type that expressed KI-67. In contrast, ductal basal cell populations did not expand in the prostates of older dogs and were seldom positively stained for KI-67. The numbers of HMC and KI-67-stained acinar basal cells were dramatically increased in the prostates of intact dogs treated with DHT when compared with glands of untreated controls. This was not the case with ductal basal cells. Androgens given alone or together with estrogen to castrated dogs induced widespread HMC and KI-67 immunostaining in both populations of basal cells. In addition, our results indicate that the majority of canine prostatic carcinomas likely arise exclusively from ductal epithelium. Only one of the 19 cases of carcinoma contained cells that expressed AR which suggests that androgens may not be required for the initiation or progression of these cancers.

CONCLUSIONS

Our findings indicate that two biologically distinct populations of basal cells may exist in the canine prostate. In this regard the age-related expansion of proliferating acinar basal cell populations, probably mediated by sex steroids, is a key factor in the pathogenesis of canine prostatic hyperplasia. Additionally we find that prostatic carcinoma in the dog likely arises from ductal cells. Taken together these findings may indicate that canine acinar basal cells and ductal epithelium have separate susceptibilities to factors that promote hyperplastic or neoplastic development. Prostate 47:149-163, 2001.

Androgen-driven prostate epithelial cell proliferation and differentiation in vivo involve the regulation of p27

Androgens control both growth and differentiation of the normal prostate gland. However, the mechanisms by which androgens act upon the cell cycle machinery to regulate these two fundamental processes are largely unknown. The cyclin-dependent kinase (cdk) inhibitor p27 is a negative cell cycle regulator involved in differentiation-associated growth arrest. Here, we investigate the role and regulation of p27 in the testosterone proprionate (TP)-stimulated regeneration of the ventral prostate (VP) of castrated rats. Continuous TP administration to castrated rats triggered epithelial cell proliferation, which peaked at 72 h, and then declined despite further treatment. Castration-induced atrophy of the VP was associated with a significant increase in p27 expression as compared with the VP of intact animals. Twelve hours after the initiation of androgen treatment, total p27 levels as well as its fraction bound to cdk2, its main target, significantly dropped in the VP of castrated rats. Thereafter, concomitantly to the induction of epithelial cell proliferation, the glandular morphology of VP was progressively restored at 48-96 h of TP treatment. During this period of the regenerative process, whereas both proliferating basal and secretory epithelial cells did not express p27, the protein was selectively up-regulated in the nonproliferating secretory epithelial compartment. This up-regulation of p27 expression was coincident with an increase in its association with, and presumably inhibition of, cdk2. At each time point of TP treatment, p27 abundance in the VP was inversely correlated with the level of its proteasome-dependent degradation activity measured in vitro in VP lysates, whereas only slight changes in the amount of p27 transcripts were detected. In addition, the antiandrogen flutamide blocked maximal TP-induced p27 degradation completely. Finally, the expression of skp2, the ubiquitin ligase that targets p27 for degradation, was seen to increase with androgen administration, preceding maximal proliferation and concomitantly to augmented p27 degradation activity. Taken together, our data indicate that androgens mediate both proliferation and differentiation signals in normal prostate epithelial cells in vivo, through regulation of p27.

Immunohistochemical localization of cyclooxygenase-1 and cyclooxygenase-2 in the human fetal and adult male reproductive tracts

The first rate-limiting step in the conversion of arachidonic acid to PGs is catalyzed by cyclooxygenase (Cox). Two isoforms of Cox have been identified, Cox-1 (constitutively expressed) and Cox-2 (inducible form), which are the products of two different genes. In this study we describe the immunohistochemical localization of Cox-1 and -2 in the human male fetal and adult reproductive tracts. There was no Cox-1 expression in fetal samples (prostate, seminal vesicles, or ejaculatory ducts), and only minimal expression in adult tissues. There was no expression of Cox-2 in the fetal prostate. In a prepubertal prostate there was some Cox-2 expression that localized exclusively to the smooth muscle cells of the transition zone. In adult hyperplastic prostates, Cox-2 was strongly expressed in smooth muscle cells, with no expression in the luminal epithelial cells. Cox-2 was strongly expressed in epithelial cells of both fetal and adult seminal vesicles and ejaculatory ducts. The Cox-2 staining intensity in the fetal ejaculatory ducts during various times of gestation correlated with previously reported testosterone production rates by the fetal testis. These data indicate that Cox-2 is the predominant isoform expressed in the fetal male reproductive tract, and its expression may be regulated by androgens. The distinct cell type-specific expression patterns of Cox-2 in the prostate (smooth muscle) vs. the seminal vesicles and ejaculatory ducts (epithelium) may reflect the different roles of PGs in these tissues.

Prolactin receptor expression in the developing human prostate and in hyperplastic, dysplastic, and neoplastic lesions

In situ hybridization and immunohistochemistry were used to localize and compare the expression of the long form of the human prolactin receptor in fetal, prepubertal, and adult prostate. Results were then compared with hyperplastic, dysplastic, and neoplastic lesions. Both receptor message and protein were predominately localized in epithelial cells of the fetal, neonatal, prepubertal, and normal adult prostate. In hyperplastic lesions the expression of the receptor was unchanged with respect to normal epithelial cells. Irrespective of grade, markedly enhanced expression of the receptor was evident in dysplastic lesions. In lower Gleason grade carcinomas the intensity of receptor signal at the message and protein levels approximated that found in normal prostatic epithelium. However, in foci within higher grade cancers, receptor expression appeared diminished. Results from our study suggest that prolactin action plays a role in the development and maintenance of the human prostate and may also participate in early neoplastic transformation of the gland. Diminution of receptor expression in high grade neoplasms could reflect the emergence of a population of cells that are no longer responsive to the peptide hormone.

The localization of transforming growth factor alpha and epidermal growth factor receptor in stromal and epithelial compartments of developing human prostate and hyperplastic, dysplastic, and carcinomatous lesions

To gain insight into autocrine/paracrine mechanisms that may influence normal and abnormal growth of the human prostate, we studied the immunohistochemical localization of transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFr) in fetal, neonatal, prepubertal, and young adult glands. Results were compared with findings in specimens of benign prostatic hyperplasia (BPH), dysplasia (prostatic intraepithelial neoplasia--PIN), and carcinoma. EGFr was strongly and exclusively expressed in fetal basal cells, whereas TGF-alpha was localized in these and secretory cells as well as in differentiating smooth muscle cells. In neonatal and prepubertal glands, EGFr continued to be found only in basal cells, whereas TGF-alpha was now present in smooth muscle and infrequently in secretory cells. In the normal adult prostate, the receptor was strictly localized in basal cells and in the lateral plasma membranes of secretory cells, whereas its ligand was exclusively expressed in smooth muscle. This pattern persisted in PBH, but both EGFr and TGF-alpha staining appeared to be enhanced in their respective cellular compartments. Irrespective of grade, in dysplasia diffuse-moderate EGFr and strong TGF-alpha staining were both present in a majority of secretory cells. Similarly, most cells in Gleason grade 3 and 4 carcinomas expressed both EGFr and TGF-alpha. Our findings suggest that an unregulated paracrine mode of growth attends the development of BPH, whereas malignant transformation and progression involves autocrine/paracrine mechanisms reminiscent of those found in the developing prostate.

Lack of association between enhanced TRPM-2/clusterin expression and increased apoptotic activity in sex-hormone-induced prostatic dysplasia of the Noble rat

Although the functional role of TRPM-2/clusterin in the prostate remains controversial, it has been postulated that transcriptional activation of the gene is an important mechanism in castration-induced prostatic involution and perhaps is a means for prostatic cells to escape apoptotic induction. In the present study, we have measured expression levels of TRPM-2/clusterin and apoptotic activities in the prostates of castrated Noble (NBL) rats and those treated with testosterone (T) and estradiol-17beta (E2) for 16 weeks. We have previously shown that the combined sex hormone treatment (T+E2) induces dysplasia, a purported preneoplastic lesion, exclusively in the dorsolateral prostates (DLPs) of all treated rats. In the present study, we demonstrate that, as expected, castration readily induced enhanced TRPM-2/clusterin expression, which was accompanied by increased apoptotic activity in the epithelia of DLP and ventral prostate (VP). The increase in TRPM-2/clusterin expression appeared earlier and was more dramatic in the VP than in the DLP. In sharp contrast, treatment of rats with T+E2 for 16 weeks induced augmentation of TRPM-2/clusterin expression selectively in the dysplastic lesions of the DLP but not in the lesion-free VP. The enhanced expression of TRPM-2/clusterin in the dysplastic epithelium was, however, not attended by an increase in apoptotic activity within the lesion. Thus, the observed up-regulation of TRPM-2/clusterin expression in the dysplastic foci of T+E2-treated rats occurred in animals whose androgen status remained normal and, despite the increased level of expression of this gene, apoptotic activity in these lesions was unchanged from basal values measured in the DLPs of untreated rats. These findings suggest that TRPM-2/clusterin expression in dysplastic lesions was no longer repressed by androgen nor was it associated with apoptosis. We propose that overexpression of the gene is likely a phenotype of neoplastic transformation. In addition, we speculate that TRPM-2/clusterin may serve as a survival factor, which could favor accumulation of transformed cells in dysplastic foci and thus promote the carcinogenic process.

Rat estrogen receptor-alpha and -beta, and progesterone receptor mRNA expression in various prostatic lobes and microdissected normal and dysplastic epithelial tissues of the Noble rats

Semiquantitative RT-PCR was used to determine if transcripts of the two estrogen receptor (ER) subtypes, ER alpha and ER beta, and the progesterone receptor (PR) are differentially expressed and/or regulated in the various normal lobes of the Noble (NBL) rat prostate. We found that ER beta mRNA was present at comparable, high levels in all three major prostatic lobes: dorsal (DP), lateral (LP) and ventral (VP) prostate. ER alpha mRNA was, however, expressed at low levels among the various lobes in the following descending order of abundance: LP>DP>VP. Expression of PR transcript was low and paralleled the expression pattern of ER alpha mRNA. Treatments of rats with testosterone (T) plus estradiol-17beta (E2) (T+E2) or T alone induced no discernible alterations in ER alpha, ER beta, and PR mRNA levels in the VP, DP and LP, while those with E2 caused a general decline in the expression of all three transcripts. We then studied the expression of the three receptors in the normal and dysplastic epithelium of the dorsolateral prostates (DLPs) of rats treated with T+E2. Comparable levels of ER beta mRNA were found in microdissected dysplastic and normal epithelia. In contrast, significantly higher levels of PR mRNA were present in epithelial samples from dysplastic acini. ER alpha mRNA was not detected in any of the microdissected epithelial samples. Results from this study suggest that upregulation of PR mRNA expression, likely mediated via ER beta action, is involved in the genesis of T+E2-induced dysplasia in this animal model.

Suppression of testosterone and estradiol-17beta-induced dysplasia in the dorsolateral prostate of Noble rats by bromocriptine

We, and others, have previously described the histological changes that occur in the prostate gland of intact Noble (NBL) rats following prolonged hormonal treatment. Dysplasia, a pre-neoplastic lesion, develops specifically in the dorsolateral prostates (DLPs) of NBL rats treated for 16 weeks with a combined regimen of testosterone (T) and estradiol-17beta (E2) (T + E2-treated rats). Concurrent with DLP dysplasia induction, the dual hormone regimen also elicits hyperprolactinemia, in addition to an elevation of nuclear type II estrogen binding sites (type II EBS), no alteration in estrogen receptors (ER), and marked epithelial cell proliferation in the dysplastic foci. The aim of this study was to investigate whether the dual hormone action is mediated via E2-induced hyperprolactinemia. Bromocriptine (Br), at a dose of 4 mg/kg body wt per day, was used to suppress pituitary prolactin (PRL) release. Serum PRL levels were lowered from values of 341 +/- 50 ng/ml in T + E2-treated rats to 32 +/- 10 ng/ml in Br co-treated animals. The latter values were comparable to those in untreated control rats. In addition, Br co-treatment effectively inhibited the evolution of dysplasia (six out of eight rats) and the often associated inflammation (five out of eight rats) in most animals. In contrast, Br co-treatment did not suppress the T + E2-induced type II EBS elevation nor alter ER levels in the DLPs of these rats, when compared with T + E2-treated rats. These data extend the many previous studies that have detailed marked influences of PRL on rat prostatic functions. However, the current study is the first to implicate PRL in prostatic dysplasia induction in vivo.

Involvement of transforming growth factor alpha (TGFalpha) and epidermal growth factor receptor (EGFR) in sex hormone-induced prostatic dysplasia and the growth of an androgen-independent transplantable carcinoma of the prostate

We previously reported the induction of dysplasia, a putative precursor of carcinoma, in the dorsolateral prostates (DLPs) of Noble rats by the combined administration of testosterone (T) and estradiol-17beta (E2) for 16 weeks. Additionally, we demonstrated growth of the AIT, a DLP-derived, androgen-independent, transplantable solid tumor, in castrated syngeneic hosts. In this investigation, using Northern blot hybridization, radioimmunoassays and radioligand assays, we showed that transforming growth factor-alpha (TGFalpha) and epidermal growth factor receptor (EGFR) were expressed at close to non-detectable levels in the ventral prostates but at low, but measurable, levels in the DLPs of untreated rats. Enhanced expression of this ligand and its receptor was detected in the DLPs harboring dysplasia and marked overexpression of these molecules was noted in the AIT. In contrast, epidermal growth factor (EGF) expression was found to be constitutively expressed, at high levels, in both normal and dysplastic DLPs, but virtually absent in the AIT. Immunohistochemical data suggested that EGF, TGFalpha and EGFR were aprocine secretory products of the normal DLP, with TGFalpha and EGF localized to the supranuclear complexes and EGFR to the apical membranes of epithelial cells. Alterations in immunostaining patterns for TGFalpha and EGFR were exclusively detected in the dysplastic lesions in the DLPs of T + E2-treated rats. Enhanced intracytoplasmic localization for both peptides were found to accompany the loss of cell polarity in dysplastic foci. Strong intracytoplasmic immunostaining for TGFalpha was observed in some AIT cells whilst staining for EGFR was present in the membranes of tumor cells that formed psuedoacini. Taken together, our findings suggest that autocrine mechanisms may play an important role early in the carcinogenic process and that progression to an androgen-independent neoplastic growth may be modulated by this signaling pathway.

Androgen receptor expression in prostatic dysplasia (prostatic intraepithelial neoplasia) in the human prostate: an immunohistochemical and in situ hybridization study

To evaluate the role of androgens in the pathogenesis of prostatic dysplasia, we compared the localization of androgen receptor (AR) in proliferative and nonproliferative cells in normal and dysplastic acini. Basal cells, the only proliferating cells identified in normal acini, contained AR mRNA but lacked an immunodetectable receptor. Both AR mRNA and immunodetectable receptor were present, however, in secretory and stromal cells. Androgen receptor localization in dysplastic lesions was identical to normal but here the proliferative marker Ki-67 was found in both basal and secretory cells. Our findings suggest that androgens do not directly initiate the division of basal cells, the putative precursors of secretory cells. Instead, the hormone may act through its fully translated receptor to mainly mediate the differentiation of secretory cells. The presence of both AR and Ki-67 in dysplastic secretory cells may indicate an abnormal direct androgen-mediated proliferation in this compartment. This is consistent with previous evidence that secretory cell differentiation is impaired in dysplasia.

Mitogen-activated protein kinase and mitogen-activated kinase phosphatase-1 expression in the Noble rat model of sex hormone-induced prostatic dysplasia and carcinoma

Our recent studies have implicated the TGF-alpha/epidermal growth factor receptor pathway in the genesis of testosterone (T) and estradiol-17 beta (E2)-induced dysplasia in the dorsolateral prostate (DLP) of Noble rats. This pathway was also found to be markedly up-regulated in the androgen-independent transplantable carcinoma that arose from the DLP of a Noble rat. In the current study, we investigated the expression of mitogen-activated protein kinase (MAP-kinase) and mitogen-activated kinase phosphatase-1 (MKP-1), key downstream regulators of growth factor-activated signal transduction in the DLP of castrated, castrated T-supplemented, and T+E2-treated rats and in the androgen-independent transplantable carcinoma. Both MAP-kinase and MKP-1 expression in the DLP were found to be dependent on androgen stimulation. Immunoblots of DLP from T+E2 treated rats demonstrated a selective decline in MKP-1 levels with no alteration in MAP-kinase expression. These findings suggest that the dual hormone treatment induces changes in the signal transduction pathway, which favors the protracted mitogenic action of MAP-kinase. In situ hybridization and immunohistochemistry findings corroborated the immunoblot data but also revealed that both MAP-kinase and MKP-1 were strongly expressed in severely dysplastic lesions, which may indicate the presence of transformed cells in these foci. In this regard, both proteins were strongly expressed in samples of the androgen-independent transplantable carcinoma. Taken together, results from this and our recent study suggest that alterations in a growth factor-MAP-kinase pathway may be important events in the initiation and progression of prostatic carcinoma.

The interaction among glucose transport, hexokinase, and glucose-6-phosphatase with respect to 3H-2-deoxyglucose retention in murine tumor models

The development of new diagnostic/therapeutic modalities for cancer requires a specific understanding of how tumors differ from normal tissues. Though the key components involved in the selective accumulation of 2-deoxy-D-glucose (2-DG) analogs in tumors are known, the relative importance of each is controversial. For this reason glucose transport protein (GLUT) density, hexokinase/glucose-6-phosphatase (GP) activity, and 2-DG biodistribution were measured together in four tumor models and normal murine tissues. Direct binding studies with 3H-cytochalasin B showed that GLUT density was elevated 20-fold in LX-1 tumors. Immunohistochemically in all tumors, the expression of GLUT-1 was highest in the necrotic/ perinecrotic foci and similar in cells not adjacent to necrotic foci. As the retention of 3H-2-DG was similar in all tumors, these data suggest that the GLUT-1 in perinecrotic tumor cells were not rate limiting for 3H-2-DG uptake. Kidney, liver, and lung had high GP activity and rapid clearance of 3H-2-DG. Sodium orthovanadate (5 mumol), a GP inhibitor, increased the concentration of 3H-2-DG in these tissues, suggesting that GP is a rate-limiting enzyme for 3H-2-DG clearance. All tumor homogenates had low GP activity, and hexokinase activity was not elevated compared to normal tissues. Thus, in the tumors studied, the selective accumulation of 3H-2-DG consistently occurred in the absence of significant GP activity without the marked overexpression of hexokinase or GLUT.

Autoradiography and radioscintigraphy of technetium-99m-sestamibi in c-neu transgenic mice

Intratumor distribution patterns of 99mTc-sestamibi and 14C-2-deoxy-D-glucose were compared in the c-neu OncoMouse, a transgenic mouse that spontaneously develops breast tumors.

METHODS

Thirty or 60 min after intravenous injection of 5 muCi 14C-2-deoxy-D-glucose and 3 mCi 99mTc-sestamibi into mice (n = 3 per time point) bearing mammary tumors (0.3-1.5 cm), the animals were analyzed for organ and tumor distribution using dual-label, whole-body autoradiography. The retention patterns of the two compounds were related to tumor morphology and viability, based on H&E-stained adjacent sections. For imaging studies, the transgenic mice (n = 9) were anesthetized with pentobarbital, injected intravenously with 5-20 mCi 99mTc-sestamibi and imaged for 60 min using a gamma camera equipped with a 1-mm pinhole collimator.

RESULTS

All positively stained tumors retained both agents, with a mean 99mTc-sestamibi tumor retention of 0.38% +/- 0.2% ID/g at 30 min compared to 4.18% +/- 0.62% ID/g for 14C-2-deoxy-D-glucose. Tumor retention of the agents remained the same at 60 min, and neither compound localized within necrotic or cystic regions of the neoplasms. Repeat imaging at 2-8-day intervals indicated a predicted sensitivity to detect a 30% difference in tumor retention of a test versus reference compound in preclinical screening.

CONCLUSION

The c-neu OncoMouse is a useful model for in vivo imaging and provides a spontaneous tumor model for preclinical screening of breast tumor imaging agents.

Induction of atypical hyperplasia, apoptosis, and type II estrogen-binding sites in the ventral prostates of Noble rats treated with testosterone and pharmacologic doses of estradiol-17 beta

BACKGROUND

We have previously shown that combined administration of testosterone (T) and a low dose of estradiol 17 beta (T+LDE2) for 16 weeks induces an atypical proliferative lesion, termed dysplasia, in the dorsolateral prostates of intact Noble rats (1, 2). The lesion was accompanied by increases in the levels of a moderate affinity, high capacity, estrogen-binding site (type II sites) found exclusively in dorsolateral prostates of these animals (1, 3). In contrast, a proliferative response and type II sites were not observed in the ventral prostates (VP) of the same rats treated with this hormonal regimen. In the current study, rats were treated with a higher dose of E2 (4 x LDE2) but the same dose of T (T+HDE2) for 16 weeks. Our aims were to determine how the VP would respond to the T+HDE2 treatment.

EXPERIMENTAL DESIGN

Intact Noble rats were treated with T+HDE2 for 16 weeks. Prostatic tissues were removed for histology, electronmicroscopy, and type II site measurements. Proliferating cells were identified by the histochemical detection of proliferating cell nuclear antigen and colcemid-arrested mitotic figures. Apoptotic cells were recognized by their characteristic histologic and ultrastructural features and by in situ detection of nuclear DNA fragmentation. Data were compared with results previously obtained from VP of rats treated with T+LDE2.

RESULTS

The VP of T+HDE2-treated animals contained focal atypical hyperplasia and wide-spread apoptosis. Proliferating cell nuclear Ag-positive-stained epithelial cells and mitotic figures were only present in foci of atypical hyperplasia. Total DNA content of the VP was significantly increased, but the tissue wet weight was not augmented. Nuclear type II sites, never observed in untreated or T+LDE2-treated rats, were detected in the VP of the majority of T+HDE2-treated animals.

CONCLUSIONS

The administration of a high dose of E2 with T produced a unique lesion in the VP, characterized by simultaneous occurrence of apoptosis and proliferation. The synergy between androgens and estrogens, via type II site induction, likely produces the proliferative response. On the other hand, inhibition of intracellular androgen activation pathways, leading to reduction in cell survival factors, may be the cause for the apoptotic development. Our model, thus, provides a unique opportunity to further study the balance/switch between cell proliferation and apoptosis that is often disturbed during cancer development.

Early alterations in ras protooncogene mRNA expression in testosterone and estradiol-17 beta induced prostatic dysplasia of noble rats

BACKGROUND

The simultaneous treatment of intact Noble rats with testosterone and estradiol-17 beta for 16 weeks consistently induces intraductal dysplasia exclusively in the dorsolateral lobe (DLP) of the prostate. The lesion closely resembles human prostatic dysplasia and is considered to be a preneoplastic alteration, since invasive carcinoma frequently develop after long-term treatment of rats with both steroids. In our current study, we investigated steady-state ras transcript expression at the earliest recognized stages of sex steroid-induced dysplasia in the DLP. Our interest in studying ras expression in these evolving lesions stems from the pivotal role this family of genes are thought to play in the regulation of cell division and differentiation as well as in the genesis of a variety of human and animal neoplasms.

EXPERIMENTAL DESIGN

Northern blotting and in situ hybridization were used to study ras protooncogene mRNA expression in the DLPs of NBL rats harboring sex steroid-induced ductal dysplasia and to compare findings with those from prostates of castrated and castrated androgen-treated animals. Since the prostate is an androgen-dependent gland, alterations in ras expression were compared with changes in the transcript levels of two androgen-responsive genes that encode for a prostatic secretory protein, seminal vesicle secretion protein II, and the androgen receptor.

RESULTS

Similar to the situation for androgen receptor expression, orchiectomy initially enhanced levels of both H- and K-ras transcripts, whereas T administration to castrates was found to return the values to levels found in intact rats. Sixteen weeks of T and E2 administration to intact rats caused levels of H-ras mRNA and a 2.4 kb K-ras transcript to rise by 50 and 60%, respectively in the DLPs with dysplasia when compared with counterpart lobes from untreated control animals. In situ hybridization revealed markedly enhanced H-ras expression in some dysplastic DLP foci and no changes in histologically normal ducts and acini.

CONCLUSIONS

Taken together, results from our studies suggest that the enhanced focal expression of ras protooncogenes may participate in early aberrant proliferation of prostatic ductal cells of the DLP. Early alterations of ras expression in dysplastic lesions may therefore be a key contributing event in the multistage development of prostate cancer in this animal model.

Immunohistochemical and in situ hybridization studies of androgen receptor expression in a transplantable androgen-independent prostatic carcinoma line (AIT) of Noble rats

BACKGROUND

In a previous study, we had shown that testosterone (T) administration to castrated Noble (NBL) rats, bearing an androgen-independent prostatic carcinoma line (AIT), caused a dramatic increase in high-affinity nuclear-androgen binding sites in the neoplasms. This increase in nuclear androgen receptors (AR) was accompanied by a transient doubling of the mitotic index in the tumors.

EXPERIMENTAL DESIGN

In our current study we used immunohistochemistry and in situ hybridization to investigate the effects of androgen withdrawal and replacement on AR expression at the molecular/cellular level in the AIT. Results from immunohistochemical studies of AR expression in the AIT were compared with those from the prostates of intact, castrated, and castrated T-treated rats.

RESULTS

Immunopositive staining for AR was found only in the nuclei of prostatic cells from the glands of intact, castrated or castrated T-treated animals. A few immunopositive tumor cells were present in AITs carried in untreated castrated hosts. In all instances, the reaction product was found in the cytoplasm, but it was also present in the nuclei of some tumor cells. Five days of T administration to castrated AIT-bearing rats caused a dramatic increase in immunopositive tumor cells. Nuclear staining was observed in all positive cells, but the reaction product was also present as well in the cytoplasm of some tumor cells. No differences in AR mRNA expression was detected by in situ hybridization studies of the AITs from castrated and castrated T-treated rats.

CONCLUSIONS

The differences in localization of AR between normal prostate and carcinoma cells may reflect alterations in DNA binding domains of the AR protein that occurred with neoplastic transformation. Our in situ findings suggest that unlike the normal prostate, where AR mRNA levels are autoregulated by androgen, AIT cells constitutively express these transcripts. Taken together, our findings suggest that the T-mediated increases in nuclear AR in the AIT, detected previously by binding assay and now by immunohistochemistry, are likely the result of post-transcriptional modifications in the receptor protein.

Comparison of 35S- and digoxigenin-labeled RNA and oligonucleotide probes for in situ hybridization. Expression of mRNA of the seminal vesicle secretion protein II and androgen receptor genes in the rat prostate

The sensitivity of radiolabeled and digoxigenin-labeled RNA probes and synthetic oligonucleotide probes for the detection of seminal vesicle secretion protein II (SVS II) and androgen receptor (AR) mRNA was compared by in situ hybridization in paraformaldehyde-fixed cryostat sections of the rat prostate. Both genes are expressed in different amounts in the various prostatic lobes and contiguous glands. SVS II or AR RNA probes were either labeled with digoxigenin-11-UTP or [35S]UTP by in vitro transcription. A synthetic SVS II oligonucleotide probe was 3' end-labeled (tailed) with either digoxigenin-11-dUTP or [35S]dATP. Hybridized 35S-labeled probes were detected by autoradiography and digoxigenin-labeled probes by immunohistochemistry using alkaline phosphatase conjugated anti-digoxigenin antibody or gold-labeled antibody followed by protein A-gold and silver enhancement. Digoxigenin-labeled probes provided the same degree of sensitivity as their 35S-labeled counterparts for the detection by in situ hybridization of weakly and strongly expressed mRNA. Using both labeling methods, the SVS II RNA probes were more sensitive than the oligonucleotide probes and background labelling of the 35S-labeled oligonucleotide probe was high. The digoxigenin method produced less background with all probe types, hybridization signals showed higher resolution and results were obtained faster than with radiolabeled probes. The immunogold silver enhancement system provided the fastest detection of digoxigenin-labeled probes with a sensitivity and resolution similar to that provided by alkaline phosphatase anti-digoxigenin immunohistochemistry. It is concluded that digoxigenin probe labeling and detection provides a sensitive, reliable, and efficient alternative to radiolabeled probes for in situ hybridization of mRNA.

Metabolism of estradiol and estrone in organ cultures of dorsolateral and ventral prostate of untreated and sex hormone-implanted rats

Since dorsolateral but not ventral prostate undergoes estrogen-induced dysplasia in the androgen-supported Noble rat in 16 weeks, we studied estrogen metabolism by these tissues from untreated and sex hormone-implanted animals. We incubated 8.5 nM [6,7-3H]-labeled estradiol (E2) and estrone (E1) for 21 hours in serum-free, prostate-lobe cultures and 8.5 nM [2-3H]E2 with explants from untreated rats and animals treated with testosterone, 5 alpha-dihydrotestosterone, or E2 plus testosterone. Untreated rat ventral prostate metabolized 3.7 times as much E2 to E1 as dorsolateral prostate, whereas the latter tissue converted 2.5 times as much E1 to E2 as the former. After dorsolateral prostate culture with 8.5 nM [6,7-3H]-labeled E2 or E1, 0.6 M KCl-extracted, Sephadex G25-excluded nuclear protein bound preponderantly E2, whereas the counterpart nuclear protein fraction from ventral prostate explants incubated with E2 bound substrate and E1 almost equally. The combination sex hormone treatment decreased E2 metabolism and increased its uptake by the dysplastic dorsolateral prostate. Implantation of 5 alpha-dihydrotestosterone, but not of testosterone, also decreased E2 metabolism to E1 by dorsolateral prostate cultures. Treatments with E2 plus testosterone and with 5 alpha-dihydrotestosterone changed E2 uptake/E1 retention in dorsolateral prostate explants from 2.4 to 7.4 and 8.5, respectively. C-2 tritium release marking the 2,3-catechol estrogen pathway was greater for ventral than dorsolateral prostate, but was unaffected by the sex hormone treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Generation of monoclonal antibodies specific for ras p21 Glu-12 oncoproteins: detection in carcinogen-induced mammary carcinomas

ras genes have been shown to become oncogenes by single point mutations which result in amino acid substitutions that affect either their GTPase activity (positions 12, 13, 59, 61) or their affinity for GTP and GDP. Ras oncogenes and their corresponding proteins have been described in a variety of human cancers as well as in animal tumors induced by physical and chemical carcinogens. One of these animal tumor systems involves the induction of mammary carcinomas in rats by a single dose of N-nitroso-N-methylurea (NMU), a methylating carcinogen. These NMU-induced mammary carcinomas contain transforming H-ras genes activated by G----A transitions in the second nucleotide of their 12th codon, presumably a consequence of the pre-mutagenic lesions induced by NMU. These G----A mutations result in the replacement of the normal glycine in the 12th position of the ras p21 protein by a glutamic acid residue. In this study, we report the generation of monoclonal antibodies (Mab) reactive with oncogenic ras p21 proteins containing glutamic acid at position 12 (p21 Glu-12). Mab designated E184 specifically recognized activated ras p21 Glu-12 proteins but not normal p21 (Gly-12) or p21 proteins activated by other position 12 substitutions including arginine, aspartic acid, cysteine, valine or serine residues. Western blot analysis of NMU-induced mammary carcinomas demonstrated that Mab E184 recognized p21 proteins expressed in these rat tumors but not p21 present in normal tissues nor in other carcinogen-induced tumors known to carry H-ras oncogenes activated by mutations at position 61.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequent activation of the Ki-ras oncogene at codon 12 in N-methyl-N-nitrosourea-induced rat prostate adenocarcinomas and neurogenic sarcomas

Rat neoplasms induced by methylating carcinogens frequently contain ras genes activated by a single point mutation. Rat prostatic tumors induced by a combination of a single injection of N-methyl-N-nitrosourea (MNU) and long-term treatment with testosterone were examined for the presence of such activating point mutations in ras genes. These tumors, which arose exclusively in the dorsolateral prostate, included both adenocarcinomas and sarcomas. Activating mutations in codon 12 of the Ki-ras gene were found in 7 of 10 carcinomas and 4 of 5 sarcomas, using selective oligonucleotide hybridization analysis of DNA amplified by the polymerase chain reaction (PCR). However, no mutated Ha-ras oncogenes were detected. The presence of PCR-engineered Hphl restriction sites created by the existence of a G35----A mutation in the rat Ki-ras oncogene identified the mutation as a GC----AT transition at the second position of codon 12. Production of O6-methylguanine adducts in the Ki-ras codon 12 followed by base mispairing during replicative DNA synthesis is thus the likely molecular mechanism of initiation of prostatic carcinogenesis by MNU in the rat. Three of the four sarcomas positive for the Ki-ras G35----A mutation were immunohistochemically defined as of Schwann cell origin, indicating that involvement of the ras gene family is possible in tumorigenesis of this cell lineage. Loss of the wild-type Ki-ras allele was also observed in all four of these sarcomas.

Heterogeneity of [3H]estradiol binding sites in the rat prostate: properties and distribution of type I and type II sites

In order to assess the rat prostate as a target tissue for receptor-mediated estrogen action, we have studied the properties and distributions of estrogen binding sites in the dorsolateral (DLP) and ventral (VP) prostate. Saturation analyses over a wide range of [3H]estradiol ([3H]E2) concentrations (0.5-100 nM) revealed two distinct types of binding sites in the cytosol and nuclear fractions of DLP of intact rats. The high affinity (type I) estrogen binding sites saturated at 2-4 nM of [3H]E2 and had a capacity of 170 fmol/mg DNA in the cytosol and 400 fmol/mg DNA in the nuclei. DLP type I sites had ligand specificity similar to that described for the classical estrogen receptors (ERs) found in female target tissues. The moderate affinity (type II) estrogen binding sites saturated at 15-30 nM of [3H]E2 and had a capacity of 850 fmol/mg DNA in the cytosol and 1600 fmol/mg DNA in the nuclei. DLP type II sites shared some characteristics of the type II ERs described for the rat uterus; they were estrogen specific, heat labile, and sensitive to reducing agents such as dithiothreitol. Saturation analyses on VP cytosols and nuclear fractions revealed only high affinity sites but no moderate affinity sites in the tissue preparations. Our finding that prostatic type II estrogen binding sites are present exclusively in the DLP supports the concept that basic biological differences exist between the two major prostatic lobes of the rat. Furthermore, our findings may help elucidate the observed differences in susceptibility between these two lobes to the hormonal induction of proliferative prostatic lesions.

Androgen-supported estrogen-enhanced epithelial proliferation in the prostates of intact Noble rats

Using a stathmokinetic in vivo metaphase-arrest technique, we studied cell proliferation and histological changes in the ventral (VP) and dorsolateral (DLP) prostate lobes of intact Noble (Nb) rats following a 16 week treatment with testosterone (T) or 5 alpha-dihydrotestosterone (DHT) administered separately or in combination with various estrogens. The combined treatment of rats with T and either estradiol-17 beta, estradiol-17 alpha, or moxestrol induced florid dysplasia and markedly elevated the mitotic index (MI) in affected regions of the DLP. In contrast, joint DHT and estrogen treatment caused only mild proliferative lesions in this lobe. The separate administration of either androgens or estrogens suppressed epithelial proliferation in both the VP and DLP, but they differed in their histological effects on these tissues. Thus DHT or T alone maintained the morphological integrity of VP and DLP, whereas E2-17 beta or moxestrol caused massive atrophy of both lobes. Although dysplastic foci were randomly scattered throughout the DLP, the most dramatic lesions occurred in periurethral ducts. With the exception of joint T and E2-17 alpha treatment, which induced proliferative alterations in the VP, dysplasia was always restricted to the DLP of all animals receiving both androgens and estrogens. Concomitant comparative stathmokinetic studies of the prostates of T-treated castrates suggest that protracted androgen-supported estrogen stimulation of the DLP is necessary to overcome factors that normally limit cell proliferation.

Biochemical alterations in sex hormone-induced hyperplasia and dysplasia of the dorsolateral prostates of Noble rats

Simultaneous implantation of intact Noble (Nb) rats with testosterone and 17 beta-estradiol (E2)-filled silastic capsules for 16 weeks caused atypical hyperplasia (dysplasia) and striking enlargement exclusively in the dorsolateral prostates (DLPs) of all animals. The dysplastic lesion may be preneoplastic since long-term administration of these steroids to Nb rats is known to induce a high incidence of adenocarcinoma in the DLP. Treatment of rats with nonaromatizable 5 alpha-dihydrotestosterone (DHT) for 16 weeks caused enlargement but not dysplasia, implicating estrogen as a key factor in the genesis of the proliferative lesion. Compared with controls, the testosterone plus E2 treatment caused a 2.5-fold increase in nuclear type II estrogen binding sites which were confined to the DLP. Neither treatment significantly altered androgen content or levels of androgen receptor in the ventral prostate or DLP. Organ cultures of enlarged DLP containing foci of dysplasia metabolized more [3H]DHT than control tissue, which resulted in increased formation of the 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-androstanediol) metabolite by these explants. Because 3 beta-androstanediol has previously been shown to displace [3H]E2 from cytosolic type I estrogen binding sites, the dysplasia may be caused by hyperstimulation of the DLP by the hormones and their normal metabolites produced in abnormal amounts.

Immunohistochemical evidence for impaired cell differentiation in the premalignant phase of prostate carcinogenesis

Epithelial cell differentiation was evaluated in 15 samples of duct-acinar dysplasia, a putative premalignant lesion of the prostate, through immunohistochemical staining for five differentiation markers. Prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), Leu-7, pepsinogen II (PG II), and tissue plasminogen activator (t-PA) are all constituents of seminal fluid that are produced by prostatic epithelium. Dysplasia foci were classified into three grades of severity and their locations mapped by camera lucida drawings of each slide. The degree of abnormal staining with each antibody was recorded on the map, and its correlation with dysplasia grade was evaluated. PSA, PAP, and Leu-7 staining were reduced in dysplasia and often absent in severe dysplasia, indicating that reduced differentiation is an early change in prostatic carcinogenesis. PG II and t-PA stains were sometimes positive in a region where they are usually absent, suggesting that deregulation of differentiation markers may accompany reduction in differentiation in these preneoplastic lesions.

Testosterone-mediated increase in 5 alpha-dihydrotestosterone content, nuclear androgen receptor levels, and cell division in an androgen-independent prostate carcinoma of Noble rats

An androgen-independent, transplantable prostate carcinoma line (AIT), originally derived from the dorsolateral prostate (DLP) of Noble rat, was implanted into orchiectomized Noble rats and its response to androgen stimulation was studied and compared to that of the regenerating DLP tissue in sexually ablated rats. AIT tumors carried in castrated hosts displayed a high basal level of proliferative activity (mitotic index (MI), 15.0 +/- 0.5) while DLP tissue in untreated castrates exhibited no proliferative activity. Following androgen stimulation by testosterone capsule implantation into host rats, the AIT responded with a marked increase in cell proliferation; MI values doubled to 30.0 +/- 2.9 on Day 5 following androgen stimulation. This androgen-induced increase in MI values was coincident with elevations in nuclear androgen receptor (20-fold increase) and 5 alpha-dihydrotestosterone content (3-fold increase) in the tumor. However, by Day 10 following androgen treatment, indices of cell proliferation in the AIT declined to pre-androgen-stimulated levels (MI, 14.8 +/- 1.9) despite the continued elevations in nuclear androgen receptor and tissue 5 alpha-dihydrotestosterone contents. Parallel changes in MI were also observed in the normal regenerating DLP following androgen stimulation. MI values in this tissue increased from nondetectable levels to 38.1 +/- 4.7 on Day 5 but declined to relatively low levels (4.5 +/- 0.9) by Day 10 following androgen replacement. Taken together these findings led us to conclude that the AIT carried in castrates is capable of responding to testosterone in a manner similar to that observed for androgen-stimulated DLP of sexually ablated rats. Thus, in both the neoplastic and regenerating tissues, the initial response to androgen is characterized by a marked enhancement of cell proliferation which was correlated with an increase in androgen receptor and 5 alpha-dihydrotestosterone content. However, like its tissue of origin, the AIT possesses mechanisms which act to limit androgen-induced cell division despite continued elevations in key parameters of androgen activation.

Differential lectin staining of central and peripheral zones of the prostate and alterations in dysplasia

Histochemical staining with a battery of ten lectins demonstrated differences in lectin binding patterns between seminal vesicle, prostatic central and peripheral zones, and foci of prostate intraductal dysplasia, a putative premalignant lesion. Lectin binding patterns of seminal vesicle and central zone of the prostate were identical except for a single lectin, supporting the concept that these two structures have a common embryologic origin from the wolffian duct. Three of the lectins that bound to central zone were not bound in peripheral zone, indicating a biologic difference between these two regions of the prostate. Dysplasia foci showed markedly reduced binding with all lectins, consistent with impaired processing of glyco-conjugates. Lectin binding patterns appear to have value as sensitive markers of differences in terminal differentiation of closely related tissues and of early impairment of differentiated function in lesions that are precursors to carcinoma. Specific patterns of lectin binding provide information on the differential carbohydrate composition of the regions of the prostate.

Calcium antagonists and heat-induced hepatic injury

Several laboratories have demonstrated the value of the isolated perfused rat liver as a suitable model for heat-induced hepatic injury in vivo. Membrane changes caused by perfusion of rat livers at 42 degrees C for 90 min were similar to those induced by toxic chemicals or hypoxia. In an evaluation of several categories of drugs reported to reduce cell injury, calcium antagonists (nifedipine, dantrolene, and verapamil), were evaluated for their therapeutic potential for heat injury. Isolated rat livers were perfused at 42 degrees C for 90 min with and without calcium antagonists. Livers were also perfused at 37 degrees C. Potassium and transaminase leakage, bile production and ultrastructure were used to evaluate their responses. Neither of the three calcium antagonists significantly improved any of the functional parameters measured. However, dantrolene produced dilated or vesicular rough endoplasmic reticulum in the heated livers. These changes suggest selective intracellular action on endoplasmic reticulum of heated livers. Ring-shaped mitochondria and vesicular endoplasmic reticulum were observed in the heated, verapamil-treated livers, but these could not be quantitatively distinguished from controls. Nifedipine did not appear to alter intracellular membranes, but did increase bile production.

C19-radiosteroid disposition in organ cultures of transplanted prostatic adenocarcinomas of the Noble rat

This study compares the disposition of 8.5-nM C19-radiosteroids in 21-h cultures of Noble rat dorsolateral prostate (DLP) and transplanted adenocarcinomas derived from the DLP. Our purpose was to determine whether differences in androgen activation could be detected between the androgen-stimulated tumor (AST) line, an androgen-independent tumor line carried in intact (AIT-I) and castrated (AIT-C) rats and their DLP tissue of origin. No differences were found between DLP, AST, AIT-I, and AIT-C for the following parameters: 5 alpha-reduction of [3H]testosterone to dihydrotestosterone (DHT); however, conversion to total 5 alpha-reduced metabolites was lower in AIT-C than DLP cultures; explant retention of [3H]testosterone-derived DHT; tissue capacity to hydroxylate [3H]5 alpha-androstane-3 beta,17 beta-diol; total and nuclear high-affinity binding of [3H]DHT to salt-extractable explant protein, except for one AIT-C which yielded half the number of binding sites. Since AIT carried in either intact or castrated hosts is competent as regards formation, retention and high-affinity binding of [3H]DHT in organ culture, we conclude that the neoplasm possesses some of the characteristics considered essential for the expression of androgen responsiveness in vivo.

Multiple phenotypes of prostatic glandular cells in castrated dogs after individual or combined treatment with androgen and estrogen. Morphometric, ultrastructural, and cytochemical distinctions

To demonstrate a potential for multidirectional differentiation in mature prostatic epithelium, 17 beta-estradiol 17-cyclopentylpropionate (ECP) and 5 alpha-androstane-3 alpha, 17 beta-diol dipropionate (3 alpha-diol DP) were administered individually and in combination to castrated dogs. Quantitative ultrastructural and cytochemical methods were used to distinguish phenotypes of glandular cells in the various hormonal environments. Castration-induced glandular cell regression was accompanied by an increased nuclear to cytoplasmic ratio; by enhanced keratin positivity, expressed as dispersed immunolabeled tonofilaments; and by an absence of peanut agglutinin (PNA) binding sites on luminal membranes. Administration of ECP resulted in squamous metaplasia as well as hypertrophy of the glandular epithelium. The hypertrophied estrogen-modified glandular (EMG) cells were characterized by a new population of small (0.29 micron in diameter) secretory granules, bundles of tonofilaments, and PNA-positive luminal membranes. Treatment of castrated dogs with 3 alpha-diol DP produced a greater epithelial hypertrophy than ECP. These cells were characterized by larger (0.49 micron in diameter) secretory granules, dispersed tonofilaments, and no detectable PNA receptors. Joint administration of ECP and 3 alpha-diol DP caused a florid response including squamous metaplasia and hypertrophy of the glandular epithelium which was associated with the emergence of a novel phenotype in androgen-estrogen modified glandular (A-EMG) cells. In A-EMG cells, secretory granules were similar in size to those found in 3 alpha-diol DP-dominated epithelium whereas tonofilaments often appeared in bundles and luminal membranes were PNA positive, i.e., features found in EMG cells. Our results indicate that atrophic canine prostatic glandular cells possess pluripotentiality of response to sex hormones.

Androgen receptor levels and androgen contents in the prostate lobes of intact and testosterone-treated Noble rats

Plasma testosterone (T) levels were correlated with androgen receptors, tissue content of T, and 5 alpha-dihydrotestosterone (DHT) in the three anatomically-discrete prostate lobes of intact and castrated Noble (Nb) rats bearing T-filled silastic capsules. Differences in androgen receptor content and tissue androgen levels were observed among the three prostatic lobes of intact Nb rats. Total (cytosolic and nuclear) androgen receptor levels were highest in the ventral prostate followed by the dorsolateral and anterior prostate lobes. In the ventral and anterior prostate, androgen receptors were found to be equally distributed between cytosols and nuclear extracts, whereas in the dorsolateral prostate, androgen receptors were predominantly nuclear (cytosolic: nuclear = 1.5). The ventral prostate had the highest total androgen content and DHT was the major tissue androgen in all three lobes. The ratio of tissue DHT:T varied among the lobes; the highest value was observed in the dorsolateral prostate. The higher proportions of nuclear androgen receptor, as well as the elevated tissue DHT:T found in the dorsolateral prostate compared to other lobes, suggest that differences in the androgen activation process may exist between the dorsolateral prostate and other prostatic lobes. Despite lower plasma and tissue T levels, the DHT content, weight and cytodifferentiation in all lobes of T-treated castrated rats closely approximated the situation found in intact animals. Total androgen receptor levels were, however, elevated in all prostatic lobes of T-treated, castrated rats as compared to intact controls. These increases were primarily attributed to the augmented levels of androgen receptor in the nuclear extracts of the three prostate lobes. Exposure of the prostate to a constant level of T, produced by silastic implantation, might be responsible for the higher total androgen receptor levels and enhanced nuclear androgen receptor retention found in the prostates of T-treated, castrated rats.

Insulin and cortisol improve heat tolerance in isolated perfused rat liver

Isolated rat livers were perfused at 37 degrees, 41 degrees, 42 degrees, and 43 degrees C with and without insulin and cortisol. Two additional groups were perfused at 42 degrees C with either hormone alone. The perfusate contained red blood cells, amino acids, and albumin in Krebs-Ringer bicarbonate. Bile flow was significantly increased by hormones at 37 degrees C. Bile flow was also increased by hormones at all other temperatures. At 41 degrees C, K+ leakage was the only parameter that indicated injury. Insulin and cortisol significantly reduced K+ leakage at this temperature compared to those without hormones. At 42 degrees C, insulin and cortisol reduced K+ leakage, increased bile flow, reduced transaminase release, and improved ultrastructural integrity. The enhanced bile flow was due primarily to insulin. A reduction in K+ leakage required both insulin and cortisol. Transaminase leakage responded to either hormone alone or in combination; however, only the cortisol-treated group showed a statistically significant reduction in transaminase leakage. At 43 degrees C, indications of irreversible injury were evident and hormones had no beneficial effects. Loss of membrane homeostasis appeared to be the initial event.

Characterization of a human, sex steroid-responsive transitional cell carcinoma maintained as a tumor line (R198) in athymic nude mice

We have established a transplantable tumor line, R198, derived from a papillary (transitional cell) carcinoma of the human urinary bladder. In nude mice, the tumor line exhibits properties attributable to both prostatic and transitional epithelia. In tumor-bearing animals given androgens, the neoplasm has a rapid growth rate, possesses low levels of measurable androgen receptors, produces tartrate-inhibitable acid phosphatase, and forms well-encapsulated, cystic tumors composed of transitional, glandular, and squamous cells. The administration of estrogens or transplantation of the tumor into female mice causes regression of the tumor. In a small percentage of the transplants placed into females or estrogenized animals, selection occurs for tumor cells which can grow under these conditions. The resulting tumors are infiltrating scirrhous carcinomas that closely resemble squamous cell carcinomas of the urinary bladder. These neoplasms grow slowly and do not possess androgen receptors or secretory material. They are composed of a homogeneous population of squamous cells which are locally invasive. The paradox of a bladder tumor with some prostatic characteristics may be explained by the fact that the tumor was derived from the trigone region of the bladder, which embryologically is formed by an admixture of tissue from the wolffian duct and the urogenital sinus. Some trigone-derived neoplasms have characteristics of both bladder and prostate. We hypothesize that sex steroid-sensitive R198, with characteristics of both bladder transitional cells and prostatic epithelia, is a tumor which phenotypically expresses the embryological origins of these tissues. As such, the tumor line will serve as a useful model for studying sex steroid-responsive cells of the urogenital epithelium.

Ultrastructural and biochemical expressions of divergent differentiation in prostates of castrated dogs treated with estrogen and androgen

To investigate the role of estrogen and androgen in prostatic differentiation and induction of epithelial hyperplasia, we studied ultrastructural and biochemical responses to estradiol-17 beta 17-cyclopentylpropionate (ECP) and 5 alpha-androstane-3 alpha, 17 beta-diol dipropionate (3 alpha-diol DP) in glands of castrated dogs. The hormones were injected individually or in combination. Organ cultures, incubated with 1.7 microM radioisotope-labeled testosterone in serum-free Trowell T8 medium, were used to compare capacities of key transforming enzymes in hormone-modified glands. High-affinity binding of labeled 8.5 nM estradiol-17 beta and 5 alpha-dihydrotestosterone (5 alpha-DHT) to 0.4 M KCl-extractable explant protein was also determined. Treatment with 1 mg. of ECP per week for 2 weeks produced basal cell mitosis and early squamous metaplasia. The glandular epithelium hypertrophied but was not repopulated. When compared with radiotestosterone disposition by explanted prostate from untreated castrates, increased formation and egress of 17-oxo C19O2 steroids, predominantly 4-androstene-3,17-dione, occurred at the expense of 5 alpha-reduced 17 beta-hydroxy C19O2-steroids and hydroxylated metabolites. Administration of 2 x 50 mg. of 3 alpha-diol DP per week for 2 weeks also induced basal cell proliferation. The glandular epithelium was repopulated, and atrophic glandular cells were partially restored. This treatment increased accumulation of radiotestosterone-derived 5 alpha-reduced C19O2-metabolites and C19O3-steroids in the explants. Joint administration of ECP and 3 alpha-diol DP yielded proliferating squamous and glandular cells within the same acinus. Each type of proliferating cell was identified by specific cytologic markers. Chromosomes were observed with tonofilament bundles in squamous cells and with secretory granules in glandular cells. However, most glandular cells were not dividing. They were characterized by co-existing tonofilament bundles and secretory granules. The dual hormone administration increased radiotestosterone metabolism. The separate effect of each hormone was notable since estrogen increased the ratio of 17-oxo C19O2 to 5 alpha-reduced 17 beta-hydroxy C19O2-metabolites, whereas androgen restored both terminal hydroxylations and high-affinity binding of 5 alpha-DHT. The levels of saturable binding of estradiol-17 beta were high but variable in explants of each treatment group. We conclude that estrogen and androgen act cooperatively and synergistically on basal cells of regressed canine prostate to induce divergently differentiated epithelial cells. Together with stromal components, these glandular and squamous cells express distinctive pathways of androgen disposition.

Estrogen-mediated exocytosis in the glandular epithelium of prostates in castrated and hypophysectomized dogs

Glandular cells in the prostate of the intact, adult dog contain numerous, large secretory granules that are released by exocytosis. Following hypophysectomy or castration, the glandular epithelium atrophies and the secretory granules degenerate and eventually disappear. Pharmacologic doses of estradiol-17 beta 17-cyclopentylpropionate cause the regressed glandular cells to synthesize a new population of smaller granules that are also released by exocytosis, even though estrogen is known to inhibit fluid secretion by the canine prostate. Thus, the mechanisms involved in prostatic synthesis and exocytosis of secretory granules are independent of those regulating fluid secretion and are operative in the absence of androgen or pituitary hormones.

Effect of low-potassium diet on rat exercise hyperthermia and heatstroke mortality

A total of 182 male Sprague-Dawley rats weighing 250-300 g were fed either a control (n = 122) diet for 32 days. The diets contained either 125 or 8 meq potassium/kg, respectively. Rats fed the low-K diet gained weight at only one-third the rate of controls (1.7 vs. 5.2 g/day), and their skeletal muscle and plasma potassium levels were reduced by 28 and 47%, respectively. When run to exhaustion at either 15 or 20 degrees C, low K+-fed rats accomplished less than one-half of the work done by the controls (26 vs. 53 kg. m) but exhibited a markedly greater rate of heat gain per kilogram-meter of work than controls (0.12 vs. 0.05 degrees C)ambient temperature of 20 degrees C, the rats of the low-K+ group despite large differences in body weight (-25%), run time temperature and twice (33 vs 17%) the mortality rate of the controls. Postexercise increases in circulating potassium (less than 90%) of heat-injured rats raised the plasma levels of low K+-fed rats to normal (5.9 +/- 2.2 meq/l). These results appear to characterize the existence of an insidious and, therefore, undocumented form of fatal exertion-induced heat illness.

Integrity of perfused rat liver at different heat loads

Isolated rat livers were perfused for 90 minutes at temperatures from 37 degrees to 43 degrees C. to evaluate the effects of heat alone on bile production, alanine aminotransferase, and asparate aminotransferase release, and light and electron microscopic structure. Bile production reached a plateau after 45 minutes at 43 degrees C. and after 60 minutes at 42 degrees C. At temperatures between 39 degrees and 41 degrees C., bile production was not significantly different from that produced at 37 degrees C. The timing and levels of alanine aminotransferase and aspartate aminotransferase released into the perfusates were similar, with increases after 45 minutes at 43 degrees C., after 60 minutes at 41 degrees and 42 degrees C. and after 75 minutes at 39 degrees and 40 degrees C. At the end of the 90-minute perfusion, light microscopy indicated vacuolization and severe dissociation of hepatocytes at 42 degrees and 43 degrees C., and pronounced centrilobular vacuolization at 41 degrees C. Electron microscopy demonstrated that hepatocytes had sustained extensive damage at 41 degrees to 43 degrees C. Mild focal and probably reversible damage occurred at 39 degrees and 40 degrees C. Since pH and O2 levels were regulated in a nonrecirculating system and perfusion rates were constant, neither acidosis, hypoxia, nor circulatory inadequacy were responsible for the alterations. Therefore, changes were attributed to the direct effects of heat, reflected a continuum from no detectable damage at 37 degrees C. to occasional necrosis of individual cells at 39 degrees to 40 degrees C. and culminated in widespread necrosis at 41 degrees to 43 degrees C. with a 90-minute exposure. These results reflect a time/temperature relationship over a range of temperatures. A hypothesis for the sequence of events in the pathogenesis of heat-induced hepatic injury is described.

Use of polyestradiol phosphate and anti-17 beta estradiol antibodies for the localization of estrogen receptors in target tissues: a critique

Polyestradiol phosphate (PEP) has been used for localization of estrogen receptors in human carcinoma. The nature of PEP binding to the receptor molecule and the ability of antiestradiol antibodies to react with estrogen receptor complexes were investigated, using an animal model system. Castrated adult female rats were injected with PEP, estradiol 17 beta-diethylstilbestrol or saline. An estrogen target organ (uterus) and a non-target organ (diaphragm) were removed from each animal. In each organ, unoccupied cytosolic estrogen receptors were quantified by DCC assay. The tissue sections were processed to ascertain the PEP binding and the ability of antiestradiol antibodies to detect hormone-occupied sites. Comparison of the results obtained by DCC assay and immunohistochemical technique revealed that antiestradiol antibodies do not react with estradiol receptor complexes formed in vitro or in vivo; that PEP cannot compete with estradiol for the receptor sites in vitro; and that PEP binds to proteins other than those measured by DCC as receptor molecules having high affinity for estradiol.

C19-Steroid metabolism by canine prostate, epididymis and perianal glands. Application of the twin-ion technique of gas chromatography/mass spectrometry to establish 7 alpha-hydroxylation

The present study applied the twin-ion technique of gas chromatography/mass spectrometry to establish 7 alpha-hydroxylation of 5 alpha-androstane-3 beta, 17 beta-diol by canine prostate, epididymis and perianal glands. 5 alpha-[4-14C, 7 beta-2H0.52]Androstane-3 beta, 17 beta-diol (0.5 microM) was incubated for 60 min at 37 degrees C with minced canine prostate and epididymis in 50 ml 0.067 M phosphate buffer (pH 7.4) containing NADPH (0.2 mM). The principal radioactive metabolite fraction was isopolar in thin-layer chromatography with 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol and contained 24% (prostate incubation) and 23% (epididymis incubation) of the radioactivity added. Following gas chromatography of the trimethylsilyl ether derivative of these metabolites, the peak with the retention time of the derivative of 5 alpha-androstane-3 beta, 7 alpah, 17 beta-triol yielded a mass spectrum consistent with that of the authentic standard triol and gave the characteristic twin-ion, though with some loss of deuterium. Incubation of 5 alpha-[4-14C, 7 beta-2H0.46]dihydrotestosterone (7 microM) and minced canine perianal glands and NADPH (0.2 mM) gave in 5% yield a transformation product with an RF-value of 5 alpha-androstane-3 beta, 7 alpha, 17 beta-triol. One half of the chromatographic fraction was subjected to gas chromatography/mass spectrometry as the free steroid, the other as the CrO3-oxidation product. The site of hydroxylation was identified as 7 alpha from the gas chromatography retention time of the free 7 beta-deuterated (twin-ion) triol and mass-spectrometry loss of deuterium in the 3,7,17-trione produced by mild CrO3 oxidation. Results of a comparative study of the metabolism of [4-14C]testosterone and 5 alpha-dihydro[4-14C]-testosterone with minced canine perianal glands and shoulder skin showed that, whereas both tissues contain a high level of 3 beta-hydroxysteroid oxidoreductase, only the perianal glands were able to transform radioactive testosterone to the 5 alpha-reduced derivatives and thence to the 7 alpha-hydroxylated product.

Effects of estrogen and androgen on the ultrastructure of secretory granules and intercellular junctions in regressed canine prostate

Epithelial cells in the prostate of the castrated or hypophysectomized dog were studied by thin-section and freeze-fracture electron microscopy to determine in vivo responses to estradiol-17 beta 17-cyclopentylpropionate (ECP) and testosterone cyclopentylpropionate (TCP). Particular attention was given to changes in specific organelles and intercellular junctions that might reflect hormone action. The few secretory granules that remain in the regressed epithelium (vestigial granules) serve as markers of prior androgen responsiveness. Pharmacologic doses of ECP caused regressed glandular cells to acquire a novel phenotype. Characteristic features of these estrogen-modified glandular (EMG) cells are newly formed secretory granules and tonofilament bundles that coexist with vestigial granules, thus demonstrating bipotentiality of response. Glandular cell-tight junctions appear unaltered by the endocrine manipulations. Although EMG cells have squamous cell features, tight junctions remain intact. Desmosomes in the canine prostate are dimorphic and are classified 70F and 100F according to the width of the filaments that converge on the dense plaques. In intact dogs, 100F desmosomes are associated with basal-reserve cells, whereas only the 70F variety is found between glandular cells. TCP treatment does not alter this distribution. Following ECP administration, both 70F and 100F desmosomes are present between EMG cells. The coexistence of newly formed secretory granules and tonofilaments of 100F desmosomes in the same EMG cell represents estrogen-induced bidirectional differentiation. Our findings indicate that androgens and estrogens are individually capable of controlling the expression of secretory granules and desmosomes. In intact animals, male and female sex hormones may act in concert to direct epithelial cell differentiation of the prostate.

Gap junctions in the myometrium of hypophysectomized estrogen-treated rats

Gap junctions, which appear in the myometrium at parturition, are believed to permit the flow of ions between smooth muscle-cell interiors thereby facilitating coordinated contractions. Gap junctions are not observed in thin-sectioned myometrium of immature hypophysectomized rats. Following estrogen administration, numerous gap junctions are present suggesting that this hormone is capable of promoting electrotonic coupling in uterine smooth muscle.

Increased survival in experimental dog heatstroke after reduction of gut flora

A study was undertaken to determine if gut flora contribute to the pathophysiology of experimental canine heatstroke. Fifty animals in four groups were anesthetized with sodium pentobarbital (25 mg/kg) intravenously. An air temperature of 42-46 degrees C was maintained adjacent to the dog with a water-heated blanket for approximately 2 h until rectal temperatures rose to 43.5 +/- 0.4 degrees C. Animals were then cooled passively in room air (28 degrees C, 20% RH) until death or until 18 h elapsed, and were euthanized. Reduction of intestine stool and bacterial contents with antibiotics, cathartics, and enemas prior to heatstroke increased the incidence of 18-h survival from 20.0% to 70.6%; antibiotics administered after heatstroke did not alter the incidence of survival over control values. These data suggest that gut flora, presumably through endotoxemia, contribute to the evolution of heatstroke pathophysiology.

Diagnostic significance of selected serum enzymes in a rat heatstroke model

A total of 171 untrained, unacclimatized, and unanesthetized rats were either exercised to exhaustion at one of four ambient temperatures (5, 20, 26, or 30 degrees C), or were restrained and heated at an ambient temperature of 41.5 degrees C until their core temperatures reached a preselected end point between 41.0 and 43.3 degrees C. The serum levels of creatine phosphokinase (CRK) and two transaminases (SGOT and SGPT) were determined at 30 min, 24, 48, 72, and 96 h posttreatment. Peak enzyme activity for CPK was noted primarily at the 30-min sampling period and at 24 h for the transaminases. The data indicated that under these conditions a) the transaminase SGOT was elevated in the serum as a consequence of the extent and duration of prior hyperthermia, b) the transaminase SGOT was released in moderate amounts after exhaustive exercise but reached its greatest activity levels following hyperthermia, and c) the activity of CPK was increased by the duration of exhaustive exercise and was less sensitive than either transaminase to prior hyperthermia. As a result, each of the three experimental conditions: a) exercise without hyperthermia, b) exercise with hyperthermia, and c) sedentary hyperthermia, produced a unique pattern of serum enzyme activity that would appear useful in diagnosing a variety of heat- and/or work-induced disorders.

Bipotentiality of response to sex hormones by the prostate of castrated or hypophysectomized dogs. Direct effects of estrogen

Prostatic response to administered estradiol-17beta 17-cyclopentylpropionate (ECP) was studied in castrated or hypophysectomized dogs. Ultrastructural investigation identified two types of epithelial cells, squamous and modified glandular, that resulted from estrogen action. Squamous cells, which predominated, appeared to evolve from basal reserve cells. Estrogen-modified glandular cells have features attributable to estrogen and previous androgen stimulation. Thaw-mount autoradiography of explants located radiolabeled estrogen in prostatic epithelium and stroma of normal and ECP-treated animals, suggesting a role of estrogen in prostatic homeostasis. Epithelium from ECP-treated dogs incorporated 3H-thymidine, indicating that estrogen promotes DNA synthesis in these cells. Greatly enhanced conversion of radiotestosterone to 4-androstene-3,17-dione, with sharply decreased formation of 5alpha-reduced hydroxylation products, and attendant elevation in estradiol-17beta oxidoreductase activity are metabolic markers attributable to the induced squamous and responding stromal cells. The duality of prostatic response to sex hormones is apparent from observations that estrogen stimulates regressed glandular epithelium which had undergone androgen-mediated differentiation before ablation.

Alterations of intercellular junctions in acinic cell carcinoma of the canine pancreas

Intercellular junctions in spontaneous canine pancreatic acinic cell adenocarcinomas were compared to those in control canine pancreas. The neoplastic cells displayed proliferation and fragmentation of tight junctions and reduction in size and number of gap junctions. Marked decrease in desmosomal density was observed only in the poorly differentiated carcinoma. In the well differentiated carcinomas a few of the desmosomes were characteristic of those found in squamous cells. No quantatitive or qualitative differences in cell junctions were noted between primary and metastatic tumor.

Peritoneal lavage cooling in an anesthetized dog heatstroke model

This study was undertaken to compare cooling in room air (27 degrees C, 20% RH), ice slush surface cooling, and peritoneal lavage cooling (6-10 degrees C) as methods for lowering body temperature in an anesthetized dog heatstroke model. We anesthetized 19 animals with sodium pentobarbital (25 mg/kg) intravenously, and maintained them in an ambient temperature of 42-46 degrees C with a water heating blanket approximately 2.0 h until rectal temperatures rose to 43.2 +/- 0.2 degrees C. At the maximum rectal temperature, the heating blankets were removed, and animals were cooled, observed until death occurred or 18 h elapsed, and then sacrificed. The data demonstrate that maximum cooling rates of rectal temperature were: peritoneal lavage, 0.56 degrees C/min; ice slush, 0.11 degrees C/min; and 27 degrees C air cooling, 0.06 degrees C/min. The incidence of 18-h survival for lavage-cooled dogs when supported with normothermic dialysis every 4 h was significantly greater than for either ice slush or air cooled dogs.