A population of oligodendrocytes derived from multipotent neural precursor cells expresses a cholinergic phenotype in culture and responds to ciliary neurotrophic factor.

Because oligodendrocytes and their precursors possess receptors for classical transmitters, and neurotransmitters such as glutamate and noradrenaline can mediate oligodendroglial proliferation and differentiation, it is possible that other neurotransmitters can also exert regulatory roles in oligodendrocyte function. We used mitogen-proliferated multipotent neuroepithelial precursors (neurospheres) and identified oligodendroglia that expressed markers traditionally found in cholinergic neurons. Regardless of culture conditions, there existed a large population of cells that resembled oligodendrocytes morphologically and coexpressed the oligodendrocyte-specific marker galactocerebroside (GalC) and the acetylcholine (ACh)-synthesizing enzyme choline acetyltransferase (ChAT). These cells did not express neuronal markers, and whole-cell recordings from cells with similar morphology displayed only outward currents in response to depolarizing voltage steps, further supporting their oligodendroglial identity. Another cholinergic marker, the vesicular ACh transporter, was also detected in GalC(+) oligodendrocytes. Furthermore, neurospheres cultured in the presence of the cholinergic receptor antagonist atropine showed a decrease in the number of GalC(+) spheres, implicating the muscarinic ACh receptor in oligodendrocyte development. The actions of neurotrophins and ciliary neurotrophic factor (CNTF) on these ChAT(+) oligodendrocytes were examined. Among these, CNTF treatment significantly increased oligodendrocytic process outgrowth. These results demonstrate classical cholinergic neuronal markers in oligodendrocytes as well as an effect of muscarinic receptor blockade on oligodendrocyte differentiation.

Detection of placental growth hormone variant and chorionic somatomammotropin-L RNA expression in normal and diabetic pregnancy by reverse transcriptase-polymerase chain reaction.

Diabetes is a common complication encountered during pregnancy. Earlier studies indicated that diabetic placentas bear morphological alterations consistent with modified placental differentiation, including alterations in the villous cellular content, structure, and total surface. Limited data associating the diabetic status with the expression of terminal placental differentiation markers are available. The human growth hormone/chorionic somatomammotropin (hGH/CS) family consists of five genes, one of which (GH-N) is expressed efficiently in pituitary while the other four (CS-A, B, L, and hGH-V) are expressed in placenta and represent ultimate placental differentiation markers. We developed and applied a sensitive RT-PCR method coupled with diagnostic restriction digestion to determine the relative levels of the hGH/CS family in normal pregnancies and examine whether their mRNA expression pattern is altered in pregnancies complicated by diabetes. We show that relative hCS-L content changes during placental development. Specifically, normal term placentas express higher relative levels of hCS-L, lower relative hGH-V levels and a 70-fold lower hGH-V/CS-L mRNA ratio compared to early placentas. Also, many term placentas from diabetic pregnancies express lower relative levels of hCS-L mRNA and a much higher hGH-V/CS-L mRNA ratio compared to normal term placenta, resembling more an early placenta pattern of expression. Thus, our study suggests that the expression of terminal placental differentiation markers, such as the hGH/CS genes, is altered in term placentas from these diabetics reflecting either impaired placental differentiation or post-differentiation impairment of normal placental function.

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer.

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Development, progression, and androgen-dependence of prostate tumors in probasin-large T antigen transgenic mice: a model for prostate cancer.

Probasin (PB) gene product is prostate-specific, epithelial cell in origin, and androgen-regulated. A large 12-kb promoter fragment of the PB gene (LPB) was linked to the simian virus 40 (SV40) large T antigen (Tag) deletion mutant (that removes the expression of the small t antigen) to deliver consistently high levels of transgene expression to the transgenic mouse prostate. Seven male founders, their male offspring, and all the male offspring from two female founders developed at least prostatic epithelial cell hyperplasia by 10 weeks of age, indicating that the incidence of transformation was 100%. Tumorigenesis in the LPB-Tag animals progressed in a manner similar to that observed in the human prostate. Initially, multifocal proliferating lesions were detected in the prostatic epithelium, which continued to progress into hyperplasia involving the entire epithelium and then low-grade dysplasia. Reactive stromal proliferation was induced and continued to develop throughout the progression to high-grade dysplasia, carcinoma in situ, and adenocarcinoma. Immunohistochemical studies indicated that most stromal cells stained positively for both androgen receptor and smooth muscle alpha-actin, suggesting that stromal overgrowth largely represented mesenchymal cells that had differentiated into smooth muscle cells. Epithelial cell transformation was accompanied by the down-regulation of differentiated function, as suggested by the loss of dorsolateral prostate-specific secretory proteins. Tumor growth was regarded as androgen-dependent because tumors regressed in animals castrated at 11 weeks of age, and androgen treatment restored both epithelial/stromal cell ratio and tumor growth. Furthermore, small populations of prostatic epithelial cells in castrated animals continued to proliferate, suggesting the potential for androgen-independent growth. Although prostatic metastasis to other organs was not observed, local invasion was detected. In summary, the LPB-Tag animal model is unique in that it is the only model generated with the Tag alone, thereby eliminating any influences of the small t antigen on prostate tumor formation. Moreover, this model undergoes molecular changes similar to those found in human prostate including: (a) the multi-focal nature of tumorigenesis, (b) the progressive histopathologic changes from low- to high-grade dysplasia similar to human prostatic intraepithelial neoplasia, (c) stimulation of reactive stromal proliferation, and (d) the androgen-dependent growth of the primary tumor. Thus, the LPB-Tag prostate tumor model will be useful for studying the sequential mechanisms underlying the development of multistep tumorigenesis.

Large fragment of the probasin promoter targets high levels of transgene expression to the prostate of transgenic mice.

BACKGROUND: Androgen regulation and prostate-specific expression of targeted genes in transgenic mice can be controlled by a small DNA fragment of the probasin (PB) promoter (-426 to +28 base pairs, bp). Although the small PB fragment was sufficient to direct prostate-specific expression, the low levels of transgene expression suggested that important upstream regulatory sequences were missing. METHODS: To enhance transgene expression, a large fragment of the PB promoter (LPB, -11,500 to +28 bp) was isolated, linked to the bacterial chloramphenicol acetyl transferase (CAT) gene, and microinjected into CD1 mouse oocytes to generate transgenic mouse lines. RESULTS: As shown by the immunohistochemical studies, CAT gene expression was restricted to the prostatic epithelial cells in a tissue-specific manner. High levels of CAT gene expression were observed in two of the six LPB-CAT transgenic lines. In Line 1, developmental regulation of LPB-CAT was detected early, from 1 to 4 weeks of age, with the activity of CAT increasing from 3 to 40,936 dpm/min/mg protein. Upon sexual maturation and elevated serum androgen levels (7 weeks of age), a further 18-fold rise in CAT activity occurred. Hormone ablation by castration in mature mice dramatically reduced transgene expression, whereas treatment with androgens returned LPB-CAT expression to precastration levels. In contrast, treatment with glucocorticoids had no significant effect on CAT gene expression. Zinc treatment of the castrated animals also increased LPB-CAT expression three- to four-fold in two prostatic lobes. CONCLUSIONS: This study demonstrates that important regulatory DNA sequences located in the LPB fragment contribute to tissue-specific expression and greatly increase levels of transgene expression induced by androgens and zinc.

Detection of placental growth hormone variant and chorionic somatomammotropin ribonucleic acid expression in human trophoblastic neoplasms by reverse transcriptase-polymerase chain reaction.

Attempts to assess human placental GH variant (hGH-V) and chorionic somatomammotropin (hCS) RNA in choriocarcinoma cell lines have been hampered by low levels of expression and limited sensitivity of RNA blotting analysis. We examined human choriocarcinoma BeWo, JAR, and JEG-3 cell lines as well as samples of complete hydatidiform moles for expression of members of the human GH (hGH) gene family using reverse transcriptase-polymerase chain reaction. A single and common set of primers was designed and used to detect products of the hGH/hCS genes as well as distinguish processed RNA from any contaminating DNA. Transcripts from the hCS genes hCS-A and -B were distinguished from placental hGH variant (hGH-V) and hCS-like (hCS-L) gene RNA by diagnostic restriction digestion of the polymerase chain reaction products. The expected pattern of hGH/hCS RNA expression was detected in term placenta, where hCS and hGH-V/hCS-L transcripts represented approximately 95% and approximately 5% of the total hGH/hCS RNA, respectively. The level of hCS RNA varied from 22-99% of the total hGH/hCS RNA in the neoplastic trophoblast samples, and variable levels of hGH-V and hCS-L RNA were also observed. In choriocarcinoma JAR cells, hGH-V RNA represented approximately 78% of the total hGH/hCS RNA compared to approximately 22% for hCS. Further, although low hCS-L RNA levels (< 1%) were found in term placenta and two of the hydatidiform moles, hCS-L transcripts represented 11% of the total hGH/hCS RNA in a third hydatidiform mole. Finally, in contrast to the detection of variable levels of hCS-L RNA in term placenta and hydatidiform mole samples, no hCS-L transcripts were detected in the three choriocarcinoma cell lines examined. These patterns reflect either deregulated hGH/hCS gene expression in neoplastic trophoblasts or differences that accompany the process of differentiation of trophoblast subpopulations. Regardless, this suggests that the control of hGH-V and hCS-L gene expression is distinct from that of the hCS-A and hCS-B genes and raises questions about the possible involvement of hGH/hCS family members in the pathology of placental abnormalities.

The rat probasin gene promoter directs hormonally and developmentally regulated expression of a heterologous gene specifically to the prostate in transgenic mice.

An expression cassette carrying 426 basepairs of the rat probasin (PB) gene promoter and 28 basepairs of 5'-untranslated region is sufficient to target the expression of the bacterial chloramphenicol acetyltransferase (CAT) gene specifically to the prostate in transgenic mice. The PB-CAT transgene was expressed in three of five (60%) independent lines of mice, and this expression, as reported previously for the endogenous rat gene, was male specific, restricted primarily to the lateral, dorsal, and ventral lobes of the prostate, with only very low levels of CAT activity detected in the anterior prostate and seminal vesicles. The developmental and hormonal regulation of the transgene also paralleled that reported for the rat gene, with a 70-fold increase in CAT activity in the mouse prostate observed between 2-7 weeks of age, a time corresponding to sexual maturation. PB-CAT activity in the prostate declined after castration to 3.5% of the precastration level, and the CAT activity in castrated males approached precastration levels when mice were supplemented with testosterone. Transgene expression in castrated males was not induced by dexamethasone. Coinjection of PB-CAT with a chicken lysozyme gene matrix attachment region resulted in their cointegration and further restricted the pattern of PB-CAT to the dorsolateral prostate, with suppressed expression observed in the ventral prostate. These studies demonstrate that a minimal rat probasin promoter can target heterologous gene expression specifically to the prostate in a developmentally and hormonally regulated fashion.

Expression of mRNA for epidermal growth factor, transforming growth factor-alpha and their receptor in human prostate tissue and cell lines.

Enhanced expression of the epidermal growth factor receptor (EGFR) or its ligands, epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) can increase signalling via receptor-mediated pathways which may lead to excessive proliferation and cellular transformation. Such autocrine regulation of growth has been demonstrated for prostate cancer cell lines in culture but its role in prostate cancer in vivo has not been established. To assess the potential of such a mechanism, we have examined the pathway components in prostate carcinomas (CaP) in comparison with non-malignant benign prostatic hyperplasias (BPH). In the present study, we investigate the dosage, structure and expression of EGF, TGF-alpha and EGFR genes in a series of 34 human prostate samples and 3 prostate cancer cell lines. All of the samples contained transcripts from each of the genes. The expression of pre-pro-TGF-alpha mRNA and pre-pro-EGF mRNA were significantly higher in CaP (n = 13) than BPH (n = 21) specimens (p < 0.05). The androgen-responsive prostatic carcinoma cell line, LNCaP, expressed high levels of EGF mRNA while the androgen-independent DU145 and PC-3 cell lines expressed high levels of TGF-alpha mRNA and EGFR mRNA. In general, overexpression of these mRNAs was not associated with amplification or detectable gene rearrangement; only DU145 cells demonstrated any alteration in these genes, with apparent amplification of the TGF-alpha gene. Relative to BPH, all prostate carcinomas and cell lines studied had elevated levels of mRNA for one or both mRNA coding for the ligands for EGFR.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of human papillomavirus 16 transcription in human prostate tissue.

Previously we demonstrated human papillomavirus type 16 DNA in a high proportion of benign hyperplastic (BPH) and cancerous (CaP) prostate specimens using the polymerase chain reaction (PCR). While these data designate the prostate as a possible reservoir for sexual transmission of HPV, an etiological role for the virus in prostatic neoplasia is uncertain. Since transcription of the E6/E7 genes of HPV 16 is essential for both viral replication and cellular transformation, we sought to assess the transcriptional activity of HPV 16 found in prostate tissues. The E6/E7 viral gene transcripts were identified in 5 of 10 BPH specimens and 3 of 7 CaP specimens known to contain HPV 16 DNA. Expression of the HPV viral genes is not associated preferentially with either BPH or CaP, nor is transcription observed in all samples which contain the viral genome. These findings suggest that the prostate may act as a site for HPV replication, but that HPV is unlikely to be involved in the transformation of prostatic cells.

High prevalence of human papillomavirus in prostate tissues.

Specific human papillomavirus (HPV) types are associated with benign and malignant lesions of the anogenital region including the prostate gland. Using polymerase chain reaction (PCR) amplification of type-specific HPV sequences, we have assessed the prevalence of HPV DNA in prostate tissue from 88 individuals. Amplified sequences specific for HPV 16 were found in 34 of 56 benign prostatic hyperplasias and in 14 of 27 prostatic carcinomas. In contrast, HPV 18 was identified in only three benign hyperplasias and one carcinoma, all of which also contained HPV 16 DNA. Four of five normal prostates obtained at autopsy had no detectable HPV infection; one contained HPV 16 sequences. No significant difference in the prevalence of HPV DNA is observed between patients with benign disease and those with evidence of malignancy when fragments of surgical material are analyzed. Surgical method (transurethral resection or suprapubic prostatectomy) had no effect on the frequency of HPV detection. The prevalence of HPV DNA in the small number of normal prostates analyzed was not significantly different from that in the surgical samples. The presence of HPV in prostate tissues suggests a possible reservoir for sexual transmission of types with oncogenic potential. A role for the virus in the etiology of prostatic neoplasia remains to be demonstrated.

Structural characterization of the rat seminal vesicle secretion II protein and gene.

The gene encoding rat seminal vesicle secretion II (SVS II) protein has been cloned from a rat genomic DNA library using a cDNA probe generated from rat dorsal prostate androgen-dependent mRNA. The cloned 7.3-kilobase pair genomic fragment contains approximately 5000 base pairs (bp) of the 5'-flanking region and the entire coding region of the SVS II protein within two exons. A sequence of 4156 bp of the rat SVS II gene has been determined, including 2037 bp of the 5'-flanking region, exon 1 (95 bp), intron 1 (236 bp), exon 2 (1171 bp), and 614 bp of the 3'-flanking region. The 5'-flanking region contains three conserved elements found in other seminal vesicle secretion genes (SVS IV-VI proteins) within 250 bp of the transcription start site as well as a glucocorticoid response element at position -314 in the SVS II gene. The first exon encodes a 22-amino acid leader peptide plus the first 2 amino acids of the secreted protein. The second exon encodes the remaining amino acids in the SVS II protein sequence. The mature protein contains 392 residues and has an Mr of 43,116. Concomitant with the gene analysis, the rat SVS II protein was purified to homogeneity, and 333 residues (85%) of the amino acid sequence were determined by automated Edman degradation. The DNA-deduced sequence and that determined by direct analysis of the protein are in complete agreement. The blocked NH2-terminal amino acid was identified as pyroglutamic acid by mass spectrometry and aminopeptidase digestion. A 13-residue structure with the consensus sequence GSQLKSFGQVKSS is repeated 13 times within the SVS II protein and appears to be involved in the formation of the rat copulatory plug via a transglutaminase reaction cross-linking glutamine and lysine residues. Overall, the SVS II protein sequence exhibits little structural relatedness to any other known protein sequence; however, some similarity can be found between the 13-residue repeat and another repeating structure and apparent transglutaminase substrate in the guinea pig seminal vesicle clotting protein.

Epidermal growth factor receptor mRNA levels in human prostatic tumors and cell lines.

The mitogenic activity of epidermal growth factor (EGF) is mediated by a cell surface receptor (EGF-R) which has been identified in human prostate tissues. Because of conflicting reports on the relative levels of EGF-R in prostate tumors as measured by binding of radiolabelled EGF, we have examined EGF-R expression at the level of the specific messenger RNA using a sensitive RNase protection assay. Expression of the mRNA for EGF-R was higher in carcinoma (CaP, N = 38) than in benign prostatic hyperplasia (BPH, N = 35) samples (p less than 0.01). The highest levels of EGF-R mRNA were found in the human prostatic carcinoma cell lines, PC-3 and DU145. Among the CaP samples, there was an association of higher EGF-R mRNA levels with higher tumor extent and dedifferentiation. Since EGF has also been found in prostatic tissues, the enhanced expression of the EGF-R gene may play a role in the growth of prostate tumors, possibly by an autocrine pathway.

Detection of papillomavirus DNA in human prostatic tissue by Southern blot analysis.

Human papillomavirus deoxyribonucleic acid was detected in prostate tissue from patients with benign prostatic hyperplasia or prostatic carcinoma. Radiolabelled genomic probes, specific for the sexually transmitted human papillomavirus types 16 and 18, were used to detect viral genomic sequences in prostate DNA samples analyzed by the Southern blot technique. Viral sequences were identified in DNA from 7 of 16 prostate samples including both hyperplastic and carcinoma tissues and including tissues obtained by transurethral resection or suprapubic prostatectomy. These data indicate that the prostate gland can be infected with human papillomavirus and imply that the prostate may act as a reservoir for the sexual transmission of papillomavirus via seminal fluid. The detection of both episomal and integrated viral DNA sequences in prostate tissue may have important implications for the etiology of prostate disease.

Detection of human papillomavirus DNA in prostate gland tissue by using the polymerase chain reaction amplification assay.

Human papillomavirus (HPV) is associated with specific benign and malignant lesions of the epithelial and mucosal surfaces. Of the sexually transmitted types, HPV type 16 (HPV 16) and HPV 18 are commonly associated with severe dysplasia and carcinoma of the uterine cervix. In men, genital HPV infections which have been studied are manifest as external lesions usually involving types other than 16 and 18. The nature of HPV 16 and 18 infections in men has not been explored. Since the most common neoplasias of the male genital tract involve the prostate gland, we assayed benign hyperplastic and cancerous prostate tumors for the presence of HPV DNA, using type-specific primers in polymerase chain reaction amplifications. Normal prostatic tissue obtained at autopsy was included in the survey. Amplified sequences specific for HPV 16 were found in 14 of 15 benign prostatic hyperplasias and in all of four carcinomas tested. In contrast, HPV 18 was identified in only three benign hyperplasias, which also contained HPV 16 DNA. Four of five normal prostates demonstrated no HPV infection; one contained HPV 16 sequences. The presence of these oncogenic HPV types in prostate tissues suggests a reservoir for sexual transmission; a potential role for the virus in the etiology of prostatic neoplasia remains to be demonstrated.

Regulation of a bifunctional mRNA results in synthesis of secreted and nuclear probasin.

Probasin, a rat prostatic protein, is statistically related to members of a protein family that includes serum, cellular, and nuclear proteins. In vivo, probasin appears both in the secretions and in the nucleus of prostatic epithelial cells. Using primer extension and S1 nuclease protection assays we detected only one probasin mRNA. Thus, the localization of this protein to two separate cellular regions must be encoded by this one mRNA. Furthermore, in vitro translation of synthetic probasin mRNA demonstrated that a protein containing a signal peptide and a protein lacking a signal peptide were synthesized by initiation at different AUG codons. These data are consistent with a mechanism of translational regulation of a eukaryotic bifunctional mRNA.

Post-castration rebound of an androgen regulated prostatic gene.

After castration, the rat dorsolateral prostate M-40 mRNA initially decreased then rebounded to precastrated levels. The cellular site of M-40 expression and its renewed expression after castration was defined by in situ hybridization histochemistry. In situ hybridization with either a 32P-labeled or biotin-labeled M-40 cDNA probe demonstrated that M-40 mRNA levels were higher in the lateral than dorsal prostate. A second androgen regulated gene, RWB, also was highly expressed in the lateral prostate. The biotinylated cDNA probes provided microscopic resolution of the expressing cells, revealing two distinct morphologies of lateral epithelium which expressed both the M-40 and RWB mRNA. These morphologies appeared in ducts which contained either epithelial cell sheets that were highly convoluted or thinner epithelial cells with a minimal degree of convolution. The RWB mRNA decreased in both cell populations in response to androgen withdrawal. The decline and reappearance of M-40 mRNA also appeared in both epithelial cell types. These data demonstrated that after castration the M-40 mRNA initially decreased as expected for an androgen sensitive gene and then progressed to a fully inducible state. The mechanism of this progression remains to be elucidated.

Effect of androgens on mRNA for a secretory protein of rat dorsolateral prostate and seminal vesicles.

The androgen dependence of a highly abundant mRNA found in the rat dorsolateral prostate and seminal vesicles has been investigated using a complementary DNA clone from a rat dorsal prostate library. The 1.5 kilobase (kb) mRNA codes for a 52 000 Da translation product which is processed to 49 000 Da in the presence of microsomal membranes. This product appears to correspond to the previously described SVS II protein secreted by rat seminal vesicles and can be immunoprecipitated with anti-SVS II antiserum. Dot hybridization assays indicated that the mRNA is abundant in the dorsal and lateral prostate glands and in seminal vesicles but not in the ventral prostate, coagulating gland or other non-accessory sex tissues. Castration of mature male rats reduces the 1.5 kb mRNA 10-fold in the seminal vesicles and 7-fold in the dorsolateral prostate in 9 days. Androgen administration to one-week castrates returned the mRNA level to normal in both tissues within 48 h. The levels of the 1.5 kb mRNA are very similar in the dorsolateral prostate and seminal vesicles at maturity but distinct patterns of developmental regulation of this gene exist in the two tissues. Between 3 and 6 weeks of age, the level of the 1.5 kb mRNA increases approximately 3-fold in the dorsolateral prostate while the increase in the seminal vesicles is more than 600-fold.

Regulation of prostatic genes: role of androgens and zinc in gene expression.

Gene expression in the rat dorsolateral prostate gland has been studied using cloned cDNA probes to the most abundant expressed mRNAs. One cDNA clone (pM-40) corresponds to two closely homologous mRNAs of about 880 nucleotides which code for two proteins of 23 and 21 kilodaltons (kDa). At least the 23-kDa protein contains a signal peptide. Another clone (pRWB) corresponds to a 1550-nucleotide mRNA which codes for a 52-kDa protein which also contains a signal peptide. The steady-state levels of these specific mRNAs increase in the dorsolateral prostate with sexual maturation. In castrated mature male rats, the M-40 mRNAs are inducible either by androgens or zinc, while the RWB mRNA is only responsive to androgens. In situ cDNA-mRNA hybridization histochemistry has been used to study the localization of the M-40 and RWB gene transcripts. Both M-40 and RWB mRNAs are most abundant in the epithelium of the lateral tip of the dorsolateral prostate. Following castration, the RWB mRNA decreases, while the M-40 mRNAs continue to be expressed in isolated areas of the epithelium. These castration-resistant cells maintain normal morphology in the absence of androgens.

Expression of the c-myc protooncogene in human prostatic carcinoma and benign prostatic hyperplasia.

We have examined the level of c-myc transcripts in prostate tissue obtained from patients with both benign prostatic hyperplasia and adenocarcinoma of the prostate. A significantly higher level of c-myc transcripts is observed in patients with adenocarcinoma (P less than 0.05). In addition, a subset of patients with adenocarcinoma had levels of c-myc transcripts 2-fold higher than the mean level for this group. These preliminary results indicate that the investigation of c-myc levels as a prognostic indicator in prostatic carcinoma is warranted.