Janice G. Dodd

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

Androgen regulation and prostatic‐specific expression of targeted genes in transgenic mice can be controlled by a small DNA fragment of the probasin (PB) promoter (−426 +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.

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-α) 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 cancerin 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-α 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-α 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-α mRNA and EGFR mRNA. In general, overexpression of these mRNAs was not associated with amplification or detectable gene rearrangment; only DU145 cells demonstrated any alteration in these genes, with apparent amplification of the TGF-α 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. Thus enhanced expression of the ligands and co-expression of the EGF receptor are frequent events in human prostate tumors, consistent with the cell culture data supporting autocrine growth regulation via EGFR-mediated pathways.

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.

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.

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.

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.

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.

Post-castration rebound of an androgen regulated prostatic gene.

SummaryAfter 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.

Expression of the mouse homologue for the human GCDFP-15/PIP gene during pre- and early post-natal development

The function of the mouse submaxillary gland/prolactin inducible protein (mSMGP/mPIP), the homologue of the human gross cystic disease fluid protein 15 (GCDFP-15)/prolactin inducible protein (hPIP) remains unknown. The human gene, normally expressed in apocrine glands of healthy individuals, is aberrantly expressed in human breast cancers where it is regulated by hormones including androgens, and in prostate cancers. We have previously reported that in the adult mouse and rat, gene expression is tissue-specific for the salivary and lacrimal glands, and is hormonally regulated. In this study, we examine the endogenous pattern of mouse SMGP/PIP (mSMGP/mPIP) gene expression in mid- and late-embryonic, and in early postnatal development. Gene expression was analyzed by RT-PCR followed by Southern blot analysis, and by in situ hybridization. Gene expression was detected in the submandibular gland as early as embryonic day 14 (E14), a period that coincides with the initiation of submandibular gland development in the embryo, suggesting that mSMGP/mPIP may have a functional role in the developing gland. Nearing the end of gestation, E18, mSMGP/mPIP transcripts were localized in the proacinar cells of the gland, and gene expression continued to be maintained following birth. In addition, during early postnatal development, mSMGP/mPIP gene expression was detected in the other two major salivary glands, the sublingual and parotid, as well as in the lacrimal gland and in reproductive tissues. In the prostate, gene expression was turned off by 10 weeks of age. The spatial and temporal pattern of the mSMGP/mPIP gene expression, in addition to our recent demonstration that mSMGP/mPIP is found in mouse saliva and can bind bacteria, suggest that this protein may have a protective role in the mouse.

Feminist Science Fiction Utopia and Stargate: SG-1: “I Doubt Very Much Colonel Carter Has Even Scratched the Surface of What is Possible”

To watch the science fiction television show Stargate: SG-1 (1997–2008) is to temporarily enter a feminist world of the “possible-but-not-real” (Russ qtd. in Melzer 2). It is a deeply satisfying world, in which women scientists in the United States Air Force (USAF) occupy senior positions and have extensive, warm, and collegial interactions with each other. This is a vision of the world as it could be. Present-day women scientists do enjoy working together to solve problems rather than advancing their own careers at the expense of those around them, or at the cost of finding solutions. They do respect each other for their intelligence, commitment, and creativity. But they are also seriously underrepresented in many disciplines and their creativity is stifled by the patriarchal culture of competitive contemporary scientific inquiry. Thus the world depicted by Stargate: SG-1 is possible, but it is not real. In this article we argue that Stargate: SG-1 uses three tropes of feminist utopian science fiction (women as expert practitioners of science; a model of feminist community; and woman as alien), combined with carefully researched and accurate depictions of selected elements of USAF life, in order to make it seem possible