Isolation and characterization of the promoter of the human prostate cancer-specific DD3 gene

Rho GTPase activating protein 21-mediated regulation of prostate cancer associated 3 gene in prostate cancer cell

The overexpression of the prostate cancer antigen 3 (PCA3) gene is well-defined as a marker for prostate cancer (PCa) diagnosis. Although widely used in clinical research, PCA3 molecular mechanisms remain unknown. Herein we used phage display technology to identify putative molecules that bind to the promoter region of PCA3 gene and regulate its expression. The most frequent peptide PCA3p1 (80%) was similar to the Rho GTPase activating protein 21 (ARHGAP21) and its binding affinity was confirmed using Phage Bead ELISA. We showed that ARHGAP21 silencing in LNCaP prostate cancer cells decreased PCA3 and androgen receptor (AR) transcriptional levels and increased prune homolog 2 (PRUNE2) coding gene expression, indicating effective involvement of ARHGAP21 in androgen-dependent tumor pathway. Chromatin immunoprecipitation assay confirmed the interaction between PCA3 promoter region and ARHGAP21. This is the first study that described the role of ARHGAP21 in regulating the PCA3 gene under the androgenic pathway, standing out as a new mechanism of gene regulatory control during prostatic oncogenesis.

CRISPR editing to mimic porphyria combined with light: A new preclinical approach for prostate cancer

Thanks to its very high genome-editing efficiency, CRISPR-Cas9 technology could be a promising anticancer weapon. Clinical trials using CRISPR-Cas9 nuclease to ex vivo edit and alter immune cells are ongoing. However, to date, this strategy still has not been applied in clinical practice to directly target cancer cells. Targeting a canonical metabolic pathway essential to good functioning of cells without potential escape would represent an attractive strategy. We propose to mimic a genetic metabolic disorder in cancer cells to weaken cancer cells, independent of their genomic abnormalities. Mutations affecting the heme biosynthesis pathway are responsible for porphyria, and most of them are characterized by an accumulation of toxic photoreactive porphyrins. This study aimed to mimic porphyria by using CRISPR-Cas9 to inactivate UROS, leading to porphyrin accumulation in a prostate cancer model. Prostate cancer is the leading cancer in men and has a high mortality rate despite therapeutic progress, with a primary tumor accessible to light. By combining light with gene therapy, we obtained high efficiency in vitro and in vivo, with considerable improvement in the survival of mice. Finally, we achieved the preclinical proof-of-principle of performing cancer CRISPR gene therapy.

Oncolytic Adenovirus with SPAG9 shRNA Driven by DD3 Promoter Improved the Efficacy of Docetaxil for Prostate Cancer

Prostate cancer (PCa) is a common malignant tumor of the male urinary system and ranks the second in the causes of tumor-related deaths. Differential display code 3 (DD3) is a noncoding gene that is specifically expressed in PCa. High expression of sperm-associated antigen 9 (SPAG9) is closely related to tumorigenesis of PCa, and SPAG9 is a therapeutic target for PCa. In this study, a new oncolytic adenovirus DD3-ZD55-SPAG9 was constructed by using DD3 promoter to enhance the efficacy and safety of adenovirus. The combined use of DD3-ZD55-SPAG9 and docetaxel showed that DD3-ZD55-SPAG9 significantly improved the anti-tumor efficacy of docetaxel in PCa both in vitro and in vivo. The mechanism was related to the induction of tumor cell apoptosis and the inhibition of tumor cell invasion. In conclusion, DD3-ZD55-SPAG9 combined with docetaxel is an effective strategy for PCa therapy.

PCA3 in Prostate Cancer

Prostate cancer antigen 3 (PCA3) is a urinary biomarker for prostate cancer and has demonstrated a good specificity and sensitivity representing a minimally invasive test.PCA3 assay could be useful in combination with PSA to suggest an eventual rebiopsy in men who have had one or more previous negative prostate biopsies.Combination of multiple tumor biomarkers will be the trend in the near future to achieve the goal of evaluate the aggressiveness of cancer and at the same time reducing the number of unnecessary biopsies.

Enhancing Prostate-Cancer-Specific MRI by Genetic Amplified Nanoparticle Tumor Homing

Precise localization and visualization of early-stage prostate cancer (PCa) is critical to improve the success of focal ablation and reduce cancer mortality. However, it remains challenging under the current imaging techniques due to the heterogeneous nature of PCa and the suboptimal sensitivity of the techniques themselves. Herein, a novel genetic amplified nanoparticle tumor-homing strategy to enhance the MRI accuracy of ultrasmall PCa lesions is reported. This strategy could specifically drive TfR expressions in PCa under PCa-specific DD3 promoter, and thus remarkably increase Tf-USPIONs concentrations in a highly accurate manner while minimizing their non-specific off-target effects on normal tissues. Consequently, this strategy can pinpoint an ultrasmall PCa lesion, which is otherwise blurred in the current MRI, and thereby addresses the unmet key need in MRI imaging for focal therapy. With this proof-of-concept experiment, the synergistic gene-nano strategy holds great promise to boost the MRI effects of a wide variety of commonly used nanoscale and molecular probes that are otherwise limited. In addition, such a strategy may also be translated and applied to MR-specific imaging of other types of cancers by using their respective tumor-specific promoters.

A PCA3 gene-based transcriptional amplification system targeting primary prostate cancer

Targeting specifically primary prostate cancer (PCa) cells for immune therapy, gene therapy or molecular imaging is of high importance. The PCA3 long non-coding RNA is a unique PCa biomarker and oncogene that has been widely studied. This gene has been mainly exploited as an accurate diagnostic urine biomarker for PCa detection. In this study, the PCA3 promoter was introduced into a new transcriptional amplification system named the 3-Step Transcriptional Amplification System (PCA3-3STA) and cloned into type 5 adenovirus. PCA3-3STA activity was highly specific for PCa cells, ranging between 98.7- and 108.0-fold higher than that for benign primary prostate epithelial or non-PCa cells, respectively. In human PCa xenografts, PCA3-3STA displayed robust bioluminescent signals at levels that are sufficient to translate to positron emission tomography (PET)-based reporter imaging. Remarkably, when freshly isolated benign or cancerous prostate biopsies were infected with PCA3-3STA, the optical signal produced from primary PCa biopsies was significantly higher than from benign prostate biopsies (4.4-fold, p < 0.0001). PCA3-3STA therefore represents a PCa-specific expression system with the potential to target, with high accuracy, primary or metastatic PCa epithelial cells for imaging, vaccines, or gene therapy.

Snail-activated long non-coding RNA PCA3 up-regulates PRKD3 expression by miR-1261 sponging, thereby promotes invasion and migration of prostate cancer cells

Rapidly accumulated evidence has shown that long non-coding RNA (lncRNAs) disregulation is involved in human tumorigenesis in many cancers, including prostate cancer (PCa). LncRNAs can regulate essential pathways that contribute to tumor initiation and progression with tissue specificity, which suggests that lncRNAs could be valuable biomarkers and therapeutic targets. Prostate cancer antigen 3 (PCA3), also known as differential display code 3 (DD3), is one such lncRNA that maps to chromosome 9q21-22. PCA3 expression is highly specific to PCa. In the present study, the level of PCA3 expression in prostate cancer cells was reduced by small interfering RNA (siRNA). Subsequently, the ability of LNCaP cell proliferation, invasion, and migration of PCa was compromised both in vivo and in vitro with the occurrence of cell autophagy. Recently, a novel regulatory mechanism has been proposed in which RNAs cross talk via competing with the shared microRNAs (miRNAs). In addition, lncRNAs can directly interact with RNA-binding proteins and then bind to the gene promoter region to further regulate gene expression. The proposed competitive endogenous RNAs mediate the bioavailability of miRNAs on their targets, thus imposing another level of post-transcriptional regulation. Here, we demonstrated that binding of Snail to the promoter region of PCA3 could activate the expression of PCA3. Down-regulation of PCA3 by silencing could increase the expression of the miRNA-1261, which then targeted at the PRKD3 gene (protein kinase D3) through competitive sponging. In summary, these results suggest that the transcription factor, Snail, activated the expression of lncRNA PCA3, which could inhibit the translation of PRKD3 protein via competitive miR-1261 sponging, and thus high expression of PRKD3 further promoted invasion and migration of prostate cancer.

Long noncoding RNA PCA3 gene promoter region is related to the risk of prostate cancer on Chinese males

INTRODUCTION

Long noncoding RNA prostate cancer gene antigen 3 (PCA3) is one of the most prostate cancer-specific genes at present. Consequently, the prostate-specific expression and the sharp up-regulation of PCA3 RNA in prostate cancer suggest a unique transcriptional regulation, which possibly can be attributed to promoter polymorphism. In this study, we investigated a short tandem repeat (STR) polymorphism of TAAA in the promoter region of PCA3 gene found in our previous study in prostate cancer (PCa) patients and benign prostatic hypertrophy (BPH) patients, aiming to evaluate the association between the STR and increased risk for PCa.

MATERIAL AND METHODS

120 PCa cases and 120 benign prostatic hypertrophy (BPH) cases were identified among participants. The region encompassing the TAAA repeat was amplified with a specific primer set we designed and screened by PCR-based cloning and sequencing in paired peripheral blood leukocytes and prostate tissues. Genotype-specific risks were estimated as odds ratios (ORs) associated with 95% confidence intervals (CIs) and adjusted for age by means of unconditional logistic regression.

RESULTS

5 PCA3 TAAA STR polymorphisms and 8 genotypes were found in both peripheral blood leukocytes and prostate tissues, the carriers with more TAAA repeats were associated with increased risk for PCa than individuals having less TAAA repeats. Interestingly, 18 (15.0%) of 120 PCa patients had more (TAAA)n repeats in prostate tissues than that in peripheral blood leukocytes, and 3 (2.5%) of 120 had less (TAAA)n repeats in prostate tissues.

CONCLUSIONS

The results of this study suggest that short tandem repeat polymorphism of TAAA in the promoter region of PCA3 gene is a risk-increasing factor for prostate cancer in the Chinese population. In addition to the hereditary factor, the insertion mutation of (TAAA)n in a local tissue maybe another mechanism of the onset of PCa.

PCA3 noncoding RNA is involved in the control of prostate-cancer cell survival and modulates androgen receptor signaling

BACKGROUND

PCA3 is a non-coding RNA (ncRNA) that is highly expressed in prostate cancer (PCa) cells, but its functional role is unknown. To investigate its putative function in PCa biology, we used gene expression knockdown by small interference RNA, and also analyzed its involvement in androgen receptor (AR) signaling.

METHODS

LNCaP and PC3 cells were used as in vitro models for these functional assays, and three different siRNA sequences were specifically designed to target PCA3 exon 4. Transfected cells were analyzed by real-time qRT-PCR and cell growth, viability, and apoptosis assays. Associations between PCA3 and the androgen-receptor (AR) signaling pathway were investigated by treating LNCaP cells with 100 nM dihydrotestosterone (DHT) and with its antagonist (flutamide), and analyzing the expression of some AR-modulated genes (TMPRSS2, NDRG1, GREB1, PSA, AR, FGF8, CdK1, CdK2 and PMEPA1). PCA3 expression levels were investigated in different cell compartments by using differential centrifugation and qRT-PCR.

RESULTS

LNCaP siPCA3-transfected cells significantly inhibited cell growth and viability, and increased the proportion of cells in the sub G0/G1 phase of the cell cycle and the percentage of pyknotic nuclei, compared to those transfected with scramble siRNA (siSCr)-transfected cells. DHT-treated LNCaP cells induced a significant upregulation of PCA3 expression, which was reversed by flutamide. In siPCA3/LNCaP-transfected cells, the expression of AR target genes was downregulated compared to siSCr-transfected cells. The siPCA3 transfection also counteracted DHT stimulatory effects on the AR signaling cascade, significantly downregulating expression of the AR target gene. Analysis of PCA3 expression in different cell compartments provided evidence that the main functional roles of PCA3 occur in the nuclei and microsomal cell fractions.

CONCLUSIONS

Our findings suggest that the ncRNA PCA3 is involved in the control of PCa cell survival, in part through modulating AR signaling, which may raise new possibilities of using PCA3 knockdown as an additional therapeutic strategy for PCa control.

Prostate cancer-specific and potent antitumor effect of a DD3-controlled oncolytic virus harboring the PTEN gene

Prostate cancer is a major health problem for men in Western societies. Here we report a Prostate Cancer-Specific Targeting Gene-Viro-Therapy (CTGVT-PCa), in which PTEN was inserted into a DD3-controlled oncolytic viral vector (OV) to form Ad.DD3.E1A.E1B(Δ55)-(PTEN) or, briefly, Ad.DD3.D55-PTEN. The woodchuck post-transcriptional element (WPRE) was also introduced at the downstream of the E1A coding sequence, resulting in much higher expression of the E1A gene. DD3 is one of the most prostate cancer-specific genes and has been used as a clinical bio-diagnostic marker. PTEN is frequently inactivated in primary prostate cancers, which is crucial for prostate cancer progression. Therefore, the Ad.DD3.D55-PTEN has prostate cancer specific and potent antitumor effect. The tumor growth rate was almost completely inhibited with the final tumor volume after Ad.DD3.D55-PTEN treatment less than the initial volume at the beginning of Ad.DD3.D55-PTEN treatment, which shows the powerful antitumor effect of Ad.DD3.D55-PTEN on prostate cancer tumor growth. The CTGVT-PCa construct reported here killed all of the prostate cancer cell lines tested, such as DU145, 22RV1 and CL1, but had a reduced or no killing effect on all the non-prostate cancer cell lines tested. The mechanism of action of Ad.DD3.D55-PTEN was due to the induction of apoptosis, as detected by TUNEL assays and flow cytometry. The apoptosis was mediated by mitochondria-dependent and -independent pathways, as determined by caspase assays and mitochondrial membrane potential.

Conditionally replicating adenoviruses carrying mda-7/IL-24 for cancer therapy

BACKGROUND

Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) suppresses growth and induces apoptosis in a broad range of human cancers without significant cytotoxicity to normal cells. Conditionally replicating adenoviruses (CRAds) not only have the ability to destroy cancer cells but may also be potential vectors for the expression of therapeutic genes.

METHODS

This review provides an overview of specifications for a novel anti-tumor approach CRAds carrying IL-24, and discusses recent progress in this field.

RESULTS

Studies in multiple laboratories report that CRAds carrying IL-24 selectively induced apoptosis in some cancer cells, and enhanced selective toxicity to cancer cells when combined with chemotherapeutic agents.

CONCLUSION

CRAds carrying IL-24 may prove a novel and effective approach for the treatment of cancers.

Molecular diagnosis of prostate cancer: PCA3 and TMPRSS2:ERG gene fusion

PURPOSE

Widespread prostate specific antigen screening together with the increase in the number of biopsy cores has led to increased prostate cancer incidence. Standard diagnostic tools still cannot unequivocally predict prostate cancer progression, which often results in a significant overtreatment rate. We present recent findings on PCA3 and TMPRSS:ERG fusion, and describe their clinical implications and performance.

MATERIALS AND METHODS

The PubMed® database was searched for reports on PCA3 (130 articles), TMPRSS:ERG and ETS fusion (180 publications) since 1999.

RESULTS

In recent years advances in genetics and biotechnology have stimulated the development of noninvasive tests to detect prostate cancer. Serum and urine molecular biomarkers have been identified, of which PCA3 has already been introduced clinically. The identification of prostate cancer specific genomic aberrations, ie TMPRSS2:ERG gene fusion, might improve diagnosis and affect prostate cancer treatment.

CONCLUSIONS

Although several recently developed markers are promising, often showing increased specificity for prostate cancer detection compared to that of prostate specific antigen, their clinical application is limited. The only 2 true prostate cancer specific biomarkers identified to date remain PCA3 and TMPRSS2:ERG gene fusion.

Association of short tandem repeat polymorphism in the promoter of prostate cancer antigen 3 gene with the risk of prostate cancer

Background

PCA3 (prostate cancer antigen 3) gene is one of the most prostate cancer-specific genes at present. Consequently, the prostate-specific expression and the sharp up-regulation of PCA3 mRNA in prostate cancer suggest a unique transcriptional regulation, which possibly can be attributed to promoter polymorphism. In our study, we evaluated whether there is polymorphism in PCA3 promoter region and also assess the association of the polymorphism with prostate cancer.

Methodology/Principal Findings

We designed a specific primer set to screen the promoter of PCA3 gene by polymerase chain reaction (PCR)-based cloning and sequencing with the DNA extracted from peripheral blood samples of prostate cancer (PCa) cases (n = 186) and healthy control cases (n = 135). Genotype-specific risks were estimated as odds ratios (ORs) with associated 95% confidence intervals (CIs) by chi-square test. Possible deviation of the genotype frequencies from controls and PCa cases expected under Hardy-Weinberg equilibrium was assessed by the chi-square test. Short tandem repeat polymorphism of TAAA was found in the promoter region of PCA3 gene, five polymorphisms and eight genotypes were identified. The eight genotypes were divided into three groups: ≤10TAAA, 11TAAA, ≥12TAAA. The group 11TAAA and ≥12TAAA were associated with higher relative risk for prostate cancer than group ≤10TAAA (OR = 1.76, 95%CI = 1.07–2.89[for group 11TAAA]; OR = 5.28, 95%CI = 1.76–15.89[for group ≥12TAAA]).

Conclusions/Significance

The presence of the (TAAA)n short tandem repeat polymorphisms in the PCA3 promoter region may be a risk factor for prostate cancer in the Chinese population.

Targeting Gene-ViroTherapy for prostate cancer by DD3-driven oncolytic virus-harboring interleukin-24 gene

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in Western male population. Previous studies have demonstrated that differential display code 3 (DD3 or DD3(PCA3)) is one of the most PCa-specific genes; therefore, it has been used as a clinical diagnostic marker for PCa. In this study, we constructed an oncolytic adenovirus Ad.DD3-E1A by using the minimal DD3 promoter to replace the native viral promoter of E1A gene. In addition, Ad.DD3-E1A was armed with therapeutic gene IL-24 to enhance its antitumor activity. The resulting adenovirus, Ad.DD3-E1A-IL-24, demonstrated PCa specificity and excellent antitumor effect. Further analyses on its antitumor mechanism revealed that it has the capacity to induce apoptosis in PCa cells and inhibit angiogenesis. These results suggest that Ad.DD3-E1A-IL-24 is a promising antitumor agent that may be able to be used in the future as a treatment for PCa.

Differential expression of PCA3 and its overlapping PRUNE2 transcript in prostate cancer

BACKGROUND

PCA3 is one of the most prostate cancer (PrCa)-specific markers described so far. Recently, a new genomic structure of PCA3 as well as new flanking and overlapping gene transcripts has been identified. Furthermore, a co-regulation of PCA3 and its overlapping gene PRUNE2(BMCC1) has been suggested. Our aim was to assess the diagnostic performance of a new PCA3 isoform (PCA3-TS4) and to study the interactions between PCA3 and BMCC1 in PrCa.

METHODS

We used SYBR Green quantitative (q)PCR with specific primers to compare PCA3 and BMCC1 expression of normal versus tumor tissue of human prostate. PCA3-TS4 plasmid was created to calculate the absolute amounts of PCA3 transcripts. The androgen regulation of PCA3 and BMCC1 expression was studied in LNCaP and 22Rv1 cells stimulated with 5alpha-dihydrotestosterone.

RESULTS

We have not found any relevant diagnostic advantage of the PCA3-TS4 isoform over the "classical" PCA3 isoform in our group of PrCa patients. Additionally, PCA3-TS4 appears to be only a minor PCA3 transcript. We were also unable to confirm the hypothesis that BMCC1 isoforms are androgen-induced in vitro.

CONCLUSIONS

Despite the presence of the recently identified marginal PCA3 transcripts in human PrCa, the previously described major PCA3 isoform still constitutes the best target for diagnostic purposes. PCA3 and BMCC1 are overlapping genes in reverse orientation that do not appear to be co-regulated.

Identification of PCA3 (DD3) in prostatic carcinoma by in situ hybridization

PCA3 is a specific marker of prostatic carcinoma. However, PCA3 has been detected only at RNA level and a corresponding PCA3 protein has never been identified. The aim of this study was to develop a technique capable of detecting PCA3 RNA on histology sections and to assess the cellular location of the molecule. Forty-eight formalin-fixed paraffin-embedded blocks of prostatectomy specimens were selected for PCA3 detection by in situ hybridization by both radioactive and chromogenic methods. Of the 48 sections, 28 contained prostatic adenocarcinoma and 20 had benign tissue located distant from the tumor. Using the radioactive detection method, 26 of 28 available cases (93%) of cancers presented at least focal cytoplasmic PCA3 expression. The benign glands located in proximity of the cancer presented PCA3 expression in eight (29%) cases, whereas those situated distant to the tumor showed focal expression in 2 of 20 (10%) cases only. High-grade prostatic intraepithelial neoplasia (HGPIN) expressed PCA3 in 25 of 26 (96%) cases. With the chromogenic detection method, 22 of the 24 interpretable cases (92%) of cancers had at least focal cytoplasmic staining. Benign glands located close to neoplastic glands expressed PCA3 in 8 (33%) cases, but none of those distant to the tumor expressed the marker. HGPIN was positive in 17 of 24 (71%) cases. The sensitivity, specificity, positive predictive value and negative predictive value for the detection of cancer were 93, 79, 71 and 95% for the radioactive detective method and 92, 80, 71 and 95% for the chromogenic detection method, respectively. Our study shows that PCA3 RNA is expressed by most prostate cancers and HGPIN. Normal glands rarely express the marker, except those located in immediate proximity of neoplastic glands, suggesting the presence of precursor molecular changes.

Marqueurs biologiques du cancer de la prostate

Screening for prostate cancer is currently based on the assessment of blood prostate specific antigen (PSA). Although PSA was shown to be an adequate tool in prostate cancer screening, beginning from 4.0 ng/mL, its specificity is less significant. In men with a PSA between 4.0 and 10 ng/mL its predictive value is low. Therefore, there is a need for new instruments likely to improve the specificity of blood PSA levels between 4.0 and 10 ng/mL and the screening for prostate cancer in subjects with low PSA. Recent data are reviewed.

APTIMA PCA3 molecular urine test: development of a method to aid in the diagnosis of prostate cancer

BACKGROUND

Prostate cancer gene 3 (PCA3) encodes a prostate-specific mRNA that has shown promise as a prostate cancer diagnostic tool. This report describes the characterization of a prototype quantitative PCA3-based test for whole urine.

METHODS

Whole-urine specimens were collected after digital rectal examination from 3 groups: men scheduled for prostate biopsy (n = 70), healthy men (<45 years of age with no known prostate cancer risk factors; n = 52), and men who had undergone radical prostatectomy (n = 21). PCA3 and prostate-specific antigen (PSA) mRNAs were isolated, amplified, and quantified by use of Gen-Probe DTS400 Systems. Prostate biopsy results were correlated with the PCA3/PSA mRNA ratio, and PSA mRNA concentrations were used to normalize PCA3 signals and confirm the yield of prostate-specific RNA. Assay precision, specimen stability, and mRNA yield were also evaluated.

RESULTS

The specimen informative rate (fraction of specimens yielding sufficient RNA for analysis) was 98.2%. In this clinical research study, ROC curve analysis of prebiopsy specimens yielded an area under the curve of 0.746; sensitivity was 69% and specificity 79%. Serum PSA assay specificity was 28% for this same group. PCA3 and PSA mRNAs were undetectable in postprostatectomy specimens except for one man with recurrent prostate cancer. Assay interrun CVs were < or =12%. Both mRNAs were stable in processed urine up to 5 days at 4 degrees C and after 5 freeze-thaw cycles.

CONCLUSION

The APTIMA PCA3 assay combines simple specimen processing with precise assays and existing instruments and could add specificity to the current algorithm for prostate cancer diagnosis.

Validation of molecular targets in prostate cancer

As prostate cancer is not a single disease, it is important to identify the pivotal pathway in the patient being treated. The molecular environment is the site of current oncological research to define new therapeutic targets for hormone-refractory disease, offering the potential to eventually individualize treatment through stratification of pathways. Targets may be validated either phenotypically (e.g. androgen receptor, cadherin) or functionally (e.g. prostate cancer-specific genes). In addition, several other candidates are potentially suitable, while others await discovery. Important initial steps have been made in the search for prostate cancer stem cells; identifying stem cells and the stromal, hormonal, and other signalling molecules that influence their behaviour would have important implications for managing prostate cancer. Although individual therapeutic pathways might be ineffective in a particular molecular environment, combinations of approaches might be capable of producing synergistic effects. A multimodal approach thus might be the best solution. Determining where best to search for a molecular target, and validating whether the target is associated with a sufficiently aggressive malignant process to justify further study is difficult, but the potential benefits are enormous.

Strict regulation of CAIX(G250/MN) by HIF-1alpha in clear cell renal cell carcinoma

Renal cell carcinoma of the clear cell type (ccRCC) is associated with loss of functional von Hippel-Lindau (VHL) protein and high, homogeneous expression of the G250MN protein, an isoenzyme of the carbonic anhydrase family. High expression of G250MN is found in all ccRCCs, but not in most normal tissues, including normal human kidney. We specifically studied the mechanism of transcriptional regulation of the CAIXG250 gene in RCC. Previous studies identified Sp1 and hypoxia-inducible factor (HIF) as main regulatory transcription factors of G250MN in various non-RCC backgrounds. However, G250MN regulation in RCC has not been studied and may be differently regulated in view of the HIF accumulation under normoxic conditions due to VHL mutations. Transient transfection of different G250MN promoter constructs revealed strong promoter activity in G250MN -positive RCC cell lines, but no activity in G250MN -negative cell lines. DNase-I footprint and band-shift analysis demonstrated that Sp1 and HIF-1alpha proteins in nuclear extracts of RCC cells bind to the CAIX promoter and mutations in the most proximal Sp1 binding element or HIF binding element completely abolished CAIX promoter activity, indicating their critical importance for the activation of G250 expression in RCC. A close correlation between HIF-1alpha expression and G250MN expression was observed. In contrast, no relationship between HIF-2alpha expression and G250MN was seen. The participation of cofactor CBP/p300 in the regulation of G250 transcription was shown. In conclusion, HIF-1alpha and Sp1, in combination with CBP/p300, are crucial elements for G250MN expression in ccRCC, and CAIXG250 can be regarded as a unique HIF-1alpha target gene in ccRCC.

New targets for therapy in prostate cancer: differential display code 3 (DD3PCA3), a highly prostate cancer–specific gene

Identification of new markers for diagnosis and new targets for therapy would represent a considerable advance in the treatment of prostate cancer. Differential display code 3 (DD3(PCA3)) is a novel gene with characteristics that indicate its potentially valuable role in early identification of malignancy and in the construction of interventions directed specifically toward malignantly transformed cells. DD3(PCA3) has a messenger RNA product that is highly overexpressed in tumors. Compared with other genetic markers that are associated with prostate tissue, DD3(PCA3) is the most specific marker for malignant disease. Indeed, it is not expressed in any other normal human tissue, including breast, bladder, testis, gastrointestinal organ, and musculoskeletal tissue. This specific relation of DD3(PCA3) to prostate tissue has been confirmed by reverse transcription-polymerase chain reaction analysis. Clonal investigation of the DD3(PCA3) transcription unit indicates that the gene has 4 distinct exons, which can give rise to a number of differently sized transcripts. Open reading frame analysis has also confirmed that the DD3(PCA3) exons are populated by an unusual number of stop codons. The dramatic prostate-specific expression and pronounced upregulation of DD3(PCA3) in prostate cancer suggest a unique transcriptional regulation. A quantitative assay for DD3(PCA3) would be a potentially valuable tool for the detection of malignant cells in blood, urine, or other clinical specimens, and it could have important implications for the earlier diagnosis and molecular staging of prostate cancer. Although further studies are needed, gene therapies based on identification to delineate the range of transcription factors that interact with the DD3(PCA3) promoter represent a promising area for preclinical investigation.

[Molecular diagnostics of prostate cancer]

Although a number of studies have identified molecular markers for prostate cancer, their clinical utility remains mainly unclear. Markers, which allow improved determination of the biological aggressiveness of individual prostate cancers, may help to optimize therapeutic management of this heterogeneous tumor type. Here, a subset of molecular markers, which are intensively discussed in the literature or which are supposed to gain clinical utility in the future, are described in more detail. For a better survey, the markers are divided into (a) susceptibility markers, (b) malignancy markers, and (c) aggressiveness markers. The number of markers described as well as the inconsistency across studies in assessing their clinical utility reflect the heterogeneity of prostate cancer also on a genetic level so that it is unlikely that a single marker will gain clinical relevance. Future research must include systematic analysis of the clinical utility of not only single markers but rather of marker profiles in appropriate studies.

Non-coding ribonucleic acids--a class of their own?

Non-coding ribonucleic acids (RNAs) do not contain a peptide-encoding open reading frame and are therefore not translated into proteins. They are expressed in all phyla, and in eukaryotic cells they are found in the nucleus, cytoplasm, and mitochondria. Non-coding RNAs either can exert structural functions, as do transfer and ribosomal RNAs, or they can regulate gene expression. Non-coding RNAs with regulatory functions differ in size ranging from a few nucleotides to over 100 kb and have diverse cell- or development-specific functions. Some of the non-coding RNAs associate with human diseases. This chapter summarizes the current knowledge about regulatory non-coding RNAs.

Baculoviruses as Vectors for Gene Therapy against Human Prostate Cancer

Current curative strategies for prostate cancer are restricted to the primary tumour, and the effect of treatments to control metastatic disease is not sustained. Therefore, the application of gene therapy to prostate cancer is an attractive alternative. Baculoviruses are highly restricted insect viruses, which can enter, but not replicate in mammalian cells. Baculoviruses can incorporate large amounts of extra genetic material, and will express transgenes in mammalian cells when under the control of a mammalian or strong viral promoter. Successful gene delivery has been achieved both in vitro and in vivo and into both dividing and nondividing cells, which is important since prostate cancers divide relatively slowly. In addition, the envelope protein gp64 is sufficiently mutable to allow targeted transduction of particular cell types. In this review, the advantages of using baculoviruses for prostate cancer gene therapy are explored, and the mechanisms of viral entry and transgene expression are described.

A novel method for the determination of basal gene expression of tissue-specific promoters: an analysis of prostate-specific promoters

Because the toxicity of suicide gene therapeutics is directly related to basal promoter activity, we developed an assay to test for promoter "leakiness" using a diphtheria toxin mutant. Sequences of 15 prostate-specific gene promoter constructs were cloned in an expression plasmid (pBK; Stratagene, La Jolla, CA) backbone driving expression of an attenuated mutant of diphtheria toxin A (tox176). Low expression levels of the DT-tox176 result in significant protein synthesis inhibition reflected by a decreased expression of the luciferase activity of a simultaneously transfected CMV luciferase construct. ID50 (dose of plasmid with 50% luciferase inhibition) was calculated for each promoter construct in different cell lines. Highest transactivational activity (ID50 <75 ng) was found for the CMV promoter in all cell lines, which is in agreement with the dual luciferase assay findings. Unlike the dual luciferase findings, however, the DT-tox176 assay showed protein inhibition of CN65 (PSA promoter/enhancer) and PSE-hK2 (PSA enhancer and basal human kallikrein 2 promoter) in HEK293 and DLD cells indicating "leakiness" of these promoter constructs. Low basal promoter activity in nonprostate cell lines was found for the minimal PSA promoter, hK2, DD3, and OC promoters. The DT-tox176 assay can better predict basal promoter activity compared to less sensitive dual luciferase assay.

Gene structure and transcriptional regulation of human Gal beta1,4(3) GlcNAc alpha2,3-sialyltransferase VI (hST3Gal VI) gene in prostate cancer cell line

We describe transcriptional regulation of the human Gal beta1,4(3) GlcNAc alpha2,3-sialyltransferase VI (hST3Gal VI) gene. The 5'-RACE results indicated that two mRNA forms differ only in the 5'-untranslated region (types 1 and 2). The genomic structure shows that the transcriptional regulation of type 1 and type 2 mRNA depends on the P1 and P2 promoters, respectively. Northern blots of RNA derived from various human tissues showed that the expression level of type 2 mRNA is higher than that of type 1 in the prostate. To elucidate the molecular basis of hST3Gal VI gene expression, we isolated and functionally characterized the genomic region containing the P1 and P2 promoters of hST3Gal VI. The activity of the P2 promoter is much higher than that of the P1 promoter in the prostate adenocarcinoma cell line PC-3. The results suggested that the hST3Gal VI gene is expressed specifically by alternative promoter utilization and is regulated in a tissue-restricted fashion at the level of transcription.