Prostate-specific antigen

Circulating cell-free DNA-based multi-cancer early detection

Patients benefit considerably from early detection of cancer. Existing single-cancer tests have various limitations, which could be effectively addressed by circulating cell-free DNA (cfDNA)-based multi-cancer early detection (MCED). With sensitive detection and accurate localization of multiple cancer types at a very low and fixed false-positive rate (FPR), MCED has great potential to revolutionize early cancer detection. Herein, we review state-of-the-art approaches for cfDNA-based MCED and their limitations and discuss both technical and clinical challenges in the development and application of MCED tests. Given the constant improvements in technology and understanding of cancer biology, we propose that a cfDNA-based targeted sequencing assay that integrates multimodal features should be optimized for MCED.

A non-invasive method for concurrent detection of early-stage women-specific cancers

We integrated untargeted serum metabolomics using high-resolution mass spectrometry with data analysis using machine learning algorithms to accurately detect early stages of the women specific cancers of breast, endometrium, cervix, and ovary across diverse age-groups and ethnicities. A two-step approach was employed wherein cancer-positive samples were first identified as a group. A second multi-class algorithm then helped to distinguish between the individual cancers of the group. The approach yielded high detection sensitivity and specificity, highlighting its utility for the development of multi-cancer detection tests especially for early-stage cancers.

Raman Imaging and Fluorescence Lifetime Imaging Microscopy for Diagnosis of Cancer State and Metabolic Monitoring

Hurdles for effective tumor therapy are delayed detection and limited effectiveness of systemic drug therapies by patient-specific multidrug resistance. Non-invasive bioimaging tools such as fluorescence lifetime imaging microscopy (FLIM) and Raman-microspectroscopy have evolved over the last decade, providing the potential to be translated into clinics for early-stage disease detection, in vitro drug screening, and drug efficacy studies in personalized medicine. Accessing tissue- and cell-specific spectral signatures, Raman microspectroscopy has emerged as a diagnostic tool to identify precancerous lesions, cancer stages, or cell malignancy. In vivo Raman measurements have been enabled by recent technological advances in Raman endoscopy and signal-enhancing setups such as coherent anti-stokes Raman spectroscopy or surface-enhanced Raman spectroscopy. FLIM enables in situ investigations of metabolic processes such as glycolysis, oxidative stress, or mitochondrial activity by using the autofluorescence of co-enzymes NADH and FAD, which are associated with intrinsic proteins as a direct measure of tumor metabolism, cell death stages and drug efficacy. The combination of non-invasive and molecular-sensitive in situ techniques and advanced 3D tumor models such as patient-derived organoids or microtumors allows the recapitulation of tumor physiology and metabolism in vitro and facilitates the screening for patient-individualized drug treatment options.

Non-invasive early detection of cancer four years before conventional diagnosis using a blood test

Early detection has the potential to reduce cancer mortality, but an effective screening test must demonstrate asymptomatic cancer detection years before conventional diagnosis in a longitudinal study. In the Taizhou Longitudinal Study (TZL), 123,115 healthy subjects provided plasma samples for long-term storage and were then monitored for cancer occurrence. Here we report the preliminary results of PanSeer, a noninvasive blood test based on circulating tumor DNA methylation, on TZL plasma samples from 605 asymptomatic individuals, 191 of whom were later diagnosed with stomach, esophageal, colorectal, lung or liver cancer within four years of blood draw. We also assay plasma samples from an additional 223 cancer patients, plus 200 primary tumor and normal tissues. We show that PanSeer detects five common types of cancer in 88% (95% CI: 80-93%) of post-diagnosis patients with a specificity of 96% (95% CI: 93-98%), We also demonstrate that PanSeer detects cancer in 95% (95% CI: 89-98%) of asymptomatic individuals who were later diagnosed, though future longitudinal studies are required to confirm this result. These results demonstrate that cancer can be non-invasively detected up to four years before current standard of care.

Ratiometric Mass Spectrometry for Cell Identification and Quantitation Using Intracellular "Dual-Biomarkers"

This study proposed an easy-to-use method for cell identification and quantitation by ratiometric matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Two pairs of MS peaks in the molecular fingerprint of cells were selected as intracellular dual-biomarkers due to the stability and specificity of their ratio values in different types of hepatocellular cancer (HCC) cell lines. Five types of HCC cells can be thereafter differentiated based on these two pairs of intracellular peptides/proteins. Two types of HCC cells, Huh7 and LM3 were co-cultured as a model to test whether the method is feasible for cell quantitation. The results indicated that the ratiometric peak intensity of the two pair biomarkers exhibits linear relationship with the proportion of Huh7 cells. Furthermore, tumor heterogeneity was simulated by subcutaneously injecting the co-cultured cells into nude mice. The cell type and proportion in the section of grown tumor tissue can be discriminated using the ratiometric MALDI imaging approach. LC-MS/MS detection revealed that one of the biomarker pairs belongs to thymosin family, β4 and β10. The ratiometric MS spectral approach using intracellular dual-biomarkers might become a pervasive strategy for high-throughput cell identification and quantitation, which is vital in tumor heterogeneity study, clinical diagnosis and drug screening.

Metabolomic profiling of prostate cancer by matrix assisted laser desorption/ionization-Fourier transform ion cyclotron resonance mass spectrometry imaging using Matrix Coating Assisted by an Electric Field (MCAEF)

In this work, we combined the use of two MALDI matrices (quercetin and 9-aminoacridine), a recently developed new matrix coating technique - matrix coating assisted by an electric field (MCAEF), and matrix-assisted laser desorption/ionization - Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) to detect and image endogenous compounds in the cancerous and non-cancerous regions of three human prostate cancer (stage II) tissue specimens. After three rounds of imaging data acquisitions (i.e., quercetin for positive and negative ion detection and 9-aminoacridine for negative ion detection), and metabolite identification, a total of 1091 metabolites including 1032 lipids and 59 other metabolites were routinely detected and successfully localized. Of these compounds, 250 and 217 were only detected in either the cancerous or the non-cancerous regions respectively, although we cannot rule out the presence of these metabolites at concentrations below the detection limit. In addition, 152 of the other 624 metabolites showed differential distributions (p<0.05, t-test) between the two regions of the tissues. Further studies on a larger number of clinical specimens will need to be carried out to confirm this large number of apparently cancer-related metabolites. The successful determination of the spatial locations and abundances of these endogenous biomolecules indicated significant metabolism abnormalities - e.g., increased energy charge and under-expression of neutral acyl glycerides, in the prostate cancer samples. To our knowledge, this work has resulted in MALDI-MS imaging of the largest group of metabolites in prostate cancer thus far and demonstrated the importance of using complementary matrices for comprehensive metabolomic imaging by MALDI-MS. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.

Sensitive and selective detection of prostate-specific antigen using a photonic crystal nanolaser

The detection of low-concentration biomarkers is expected to facilitate the early diagnosis of severe diseases, including malignant tumors. Using photonic crystal nanolaser sensors, we detected prostate-specific antigen (PSA) from a concentration of 1 fM, which is difficult to detect by conventional enzyme-linked immunosorbent assay. The signal intensity and stability were improved by using a surfactant (i.e., ethanolamine). Even when a contaminant such as bovine serum albumin was mixed into the PSA sample, thereby increasing the concentration of the contaminant ten billion times, it was still possible to maintain a high level of detection.

The use of matrix coating assisted by an electric field (MCAEF) to enhance mass spectrometric imaging of human prostate cancer biomarkers

In this work, we combined a newly developed matrix coating technique - matrix coating assisted by an electric field (MCAEF) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to enhance the imaging of peptides and proteins in tissue specimens of human prostate cancer. MCAEF increased the signal-to-noise ratios of the detected proteins by a factor of 2 to 5, and 232 signals were detected within the m/z 3500-37500 mass range on a time-of-flight mass spectrometer and with the sinapinic acid MALDI matrix. Among these species, three proteins (S100-A9, S100-A10, and S100-A12) were only observed in the cancerous cell region and 14 proteins, including a fragment of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase 2, a fragment of cAMP-regulated phosphoprotein 19, 3 apolipoproteins (C-I, A-I, and A-II), 2 S100 proteins (A6 and A8), β-microseminoprotein, tumor protein D52, α-1-acid glycoprotein 1, heat shock protein β-1, prostate-specific antigen, and 2 unidentified large peptides at m/z 5002.2 and 6704.2, showed significantly differential distributions at the p < 0.05 (t-test) level between the cancerous and the noncancerous regions of the tissue. Among these 17 species, the distributions of apolipoprotein C-I, S100-A6, and S100-A8 were verified by immunohistological staining. In summary, this study resulted in the imaging of the largest group of proteins in prostate cancer tissues by MALDI-MS reported thus far, and is the first to show a correlation between S100 proteins and prostate cancer in a MS imaging study. The successful imaging of the three proteins only found in the cancerous tissues, as well as those showing differential expressions demonstrated the potential of MCAEF-MALDI/MS for the in situ detection of potential cancer biomarkers. Copyright © 2015 John Wiley & Sons, Ltd.

Plasma vascular endothelial growth factors A and C in patients undergoing prostatic biopsy and TURP for suspected prostatic neoplasia

BACKGROUND

Formation of new blood vessels is necessary for the development and spread of neoplasms more than 1 mm3 in volume, angiogenesis being responsible for formation of new from pre-existing blood vessels. Vascular endothelial growth factor (VEGF) is pivotal and the best studied angiogenic factor in all human cancers. Therefore we designed this study to investigate the role of VEGF-A and VEGF-C in prostate cancer in comparison with BPH controls in a north Indian population.

METHODS

In this case-control study a total of 100 subjects were included on the basis of confirmed histopathological reports, out of which 50 were prostate cancer patients and the other 50 were BPH patients with PSA levels >2 ng/ml and abnormal digital rectal examination (DRE) findings during September 2009 to August 2011 from the Department of Urology, KGMU, Lucknow, India. Plasma levels of VEGF were determined using quantitative immunoassay (ELISA- enzyme linked immunosorbent assay). Statistical analysis was carried out using SPSS 15.0 version.

RESULTS

The mean age of prostate cancer (67.6±5.72) patients was significantly higher (p=0.005) than BPH (63.6±7.92) patients. Expression of VEGF-A was not significantly higher in disease stage C1 than D1 or D2 and A or B (p=0.13) while the level of VEGF-A was significantly higher (p=0.04) in prostate cancer as compared to BPH subjects (PCa=13.0 pg/ml, BPH=6.8 pg/ml). Levels of VEGF-C were similar in both groups (PCa=832.6 pg/ml, BPH=823.7 pg/ml). In ROC curve, the area under curve (AUC) was 0.70 (95%CI: 0.60-0.80) and the cut-off value for which a higher proportion of patients was correctly classified (20%) was 26.0 pg/mL.

CONCLUSION

Although VEGF-A is increased in cancer prostate patients a statistically significant correlation could not be established in this study. VEGF-C was not found to be a useful biomarker.

Metabolomic imaging of prostate cancer with magnetic resonance spectroscopy and mass spectrometry

Metabolomic imaging of prostate cancer (PCa) aims to improve in vivo imaging capability so that PCa tumors can be localized noninvasively to guide biopsy and evaluated for aggressiveness prior to prostatectomy, as well as to assess and monitor PCa growth in patients with asymptomatic PCa newly diagnosed by biopsy. Metabolomics studies global variations of metabolites with which malignancy conditions can be evaluated by profiling the entire measurable metabolome, instead of focusing only on certain metabolites or isolated metabolic pathways. At present, PCa metabolomics is mainly studied by magnetic resonance spectroscopy (MRS) and mass spectrometry (MS). With MRS imaging, the anatomic image, obtained from magnetic resonance imaging, is mapped with values of disease condition-specific metabolomic profiles calculated from MRS of each location. For example, imaging of removed whole prostates has demonstrated the ability of metabolomic profiles to differentiate cancerous foci from histologically benign regions. Additionally, MS metabolomic imaging of prostate biopsies has uncovered metabolomic expression patterns that could discriminate between PCa and benign tissue. Metabolomic imaging offers the potential to identify cancer lesions to guide prostate biopsy and evaluate PCa aggressiveness noninvasively in vivo, or ex vivo to increase the power of pathology analysis. Potentially, this imaging ability could be applied not only to PCa, but also to different tissues and organs to evaluate other human malignancies and metabolic diseases.

Selective enrichment and sensitive detection of peptide and protein biomarkers in human serum using polymeric reverse micelles and MALDI-MS

Reverse-micelle forming amphiphilic homopolymers with carboxylic acid and quaternary amine substituents are used to selectively enrich biomarker peptides and protein fragments from human serum prior to matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis. After depletion of human serum albumin (HSA) and immunoglobulin G (IgG), low abundance peptide biomarkers can be selectively enriched and detected by MALDI-MS at clinically relevant concentrations by using the appropriate homopolymer(s) and extraction pH value(s). Three breast cancer peptide biomarkers, bradykinin, C4a, and ITIH(4), were chosen to test this new approach, and detection limits of 0.5 ng mL(-1), 0.08 ng mL(-1), and 0.2 ng mL(-1), respectively, were obtained. In addition, the amphiphilic homopolymers were used to detect prostate specific antigen (PSA) at concentrations as low as 0.5 ng mL(-1) by targeting a surrogate peptide fragment of this protein biomarker. Selective enrichment and sensitive MS detection of low abundance peptide/protein biomarkers by these polymeric reverse micelles should be a sensitive and straightforward approach for biomarker screening in human serum.

Vascular endothelial growth factor (VEGF) and prostate pathology

PURPOSE

Previous studies suggest that vascular endothelial growth factor (VEGF) circulating levels might improve identification of patients with prostate cancer but results are conflicting. Our aim was to compare serum VEGF levels across different prostate pathologies (including benign prostatic hyperplasia, prostatitis, high grade prostate intraepithelial neoplasia and prostate cancer) in patients at high risk of prostate cancer.

MATERIALS AND METHODS

We consecutively enrolled 186 subjects with abnormal digital rectal examination and/or total PSA (tPSA) > or = 2.5 ng/mL. Blood was collected before diagnostic ultrasound guided trans-rectal prostate biopsy, or any prostate oncology treatment, to measure PSA isoforms and VEGF. Unconditional logistic regression was used to compute age-, tPSA- and free/total PSA-adjusted odds ratios (OR) and respective 95% confidence intervals (95% CI) for the association between serum VEGF and different prostatic pathologies.

RESULTS

Prostate biopsy main diagnoses were normal or benign prostatic hyperplasia (27.3%), prostatitis (16.6%), and prostatic cancer (55.0%). The median VEGF levels (ng/mL) in these groups were 178.2, 261.3 and 266.4 (p = 0.029), respectively, but no significant differences were observed for benign vs. malignant pathologies (215.2 vs. 266.4, p = 0.551). No independent association was observed between VEGF (3rd vs. 1st third) and prostate cancer, when compared to benign conditions (adjusted OR = 1.44; CI 95%: 0.64-3.26).

CONCLUSIONS

In patients at high risk of prostate cancer, circulating VEGF levels have no clinical role in deciding which patients should be submitted to prostate biopsy. Prostatitis patients, often with higher PSA levels, also present high serum levels of VEGF, and their inclusion in control groups might explain the heterogeneous results in previous studies.

Measurement of blood E2F3 mRNA in prostate cancer by quantitative RT-PCR: a preliminary study

The use of serum prostate-specific antigen (PSA) measurements necessitates biopsies for accurate prostate cancer (CaP) diagnosis. Overall efficiency of accurate diagnosis, when PSA levels are used alone, is less than 60%. E2F3 was evaluated as an alternative biomarker using patient blood samples. Expression levels were measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and correlated with accurate clinicopathological data. Statistical analysis demonstrated significant differences in E2F3 expression levels (p<0.0001), and high levels of discrimination (receiver operator curve/area under curve analysis values (AUC) >0.88), in particular at early stages of disease development, between benign disease and localized CaP. Limited levels of discrimination were observed at the later stages of disease development, between localized and metastatic disease (p=0.076, AUC=0.633). A cut-off point of 0.34 with high specificity for benign disease (92.3%) and sensitivity for CaP diagnosis (81.0%) was identified. At this cut-off point, 85% patients were correctly diagnosed with either malignant or benign disease. This study demonstrates the strength of E2F3 as a potential marker for discriminating benign and malignant disease, addressing the current limitations of serum PSA measurements.

PSA and new biomarkers within multivariate models to improve early detection of prostate cancer

This review gives an overview of the use of prostate-specific antigen (PSA) and percent free-PSA (%fPSA)-based artificial neural networks (ANNs) and logistic regression models (LR) to reduce unnecessary prostate biopsies. There is a clear advantage in including clinical data such as age, digital rectal examination and transrectal ultrasound (TRUS) variables like prostate volume and PSA density as additional factors to tPSA and %fPSA within ANNs and LR models. There is also positive impact of tPSA and fPSA assays on the outcome of ANNs. New markers provide additional value within ANNs but to prove their clinical usefulness further testing is necessary.

Usefulness of an immunochromatographical assay, PSA Rapid Test as a primary screening test for prostate cancer

BACKGROUND

The recent rapid increase of mass screening for prostate cancer by measuring PSA in Japan will increase the economic burden to the healthcare system. PSA Rapid Test (PRT) is a simple inexpensive test. The usefulness of PRT as a primary screening test for prostate cancer was evaluated.

METHODS

When we conducted educational lectures for prostate cancer in our city, screening for prostate cancer using PRT was offered to the male participants. The results of the tests were handed to participants in writing at the end of the lectures. When the results were judged as positive, letters of referral to our institute were enclosed.

RESULTS

One hundred and fourteen (18.6%) of 614 men were judged as positive by PRT. Of the 114 men with positive PRT, 73 (64%) visited our institution. Finally, 37 men underwent a transrectal prostate biopsy and a diagnosis of prostate cancer was made in 21 men (3.4% of all participants). The total costs for the PSA tests in this study were summed to be approximately $2,300, while they would be approximately $9,200 if all participants had undergone screening using the conventional quantitative method from the outset.

CONCLUSION

PRT is a low-cost method to detect patients with prostate cancer. We believe the PRT is useful as an initial screening test for detecting prostate cancer and that the combination of the PRT and more precise quantitative testing would be a reasonable way to reduce the cost and achieve high detection rate.

Common cancer biomarkers

There is an increasing interest in complementing conventional histopathologic evaluation with molecular tools that could increase the sensitivity and specificity of cancer staging for diagnostic and prognostic purposes. This study strove to identify cancer-specific markers for the molecular detection of a broad range of cancer types. We used 373 archival samples inclusive of normal tissues of various lineages and benign or malignant tumors (predominantly colon, melanoma, ovarian, and esophageal cancers). All samples were processed identically and cohybridized with an identical reference RNA source to a custom-made cDNA array platform. The database was split into training (n = 201) and comparable prediction (n = 172) sets. Leave-one-out cross-validation and gene pairing analysis identified putative cancer biomarkers overexpressed by malignant lesions independent of tissue of derivation. In particular, seven gene pairs were identified with high predictive power (87%) in segregating malignant from benign lesions. Receiver operator characteristic curves based on the same genes could segregate malignant from benign tissues with 94% accuracy. The relevance of this study rests on the identification of a restricted number of biomarkers ubiquitously expressed by cancers of distinct histology. This has not been done before. These biomarkers could be used broadly to increase the sensitivity and accuracy of cancer staging and early detection of locoregional or systemic recurrence. Their selective expression by cancerous compared with paired normal tissues suggests an association with the oncogenic process resulting in stable expression during disease progression when the presently used differentiation markers are unreliable.

Dual activation of pathways regulated by steroid receptors and peptide growth factors in primary prostate cancer revealed by Factor Analysis of microarray data

Background

We use an approach based on Factor Analysis to analyze datasets generated for transcriptional profiling. The method groups samples into biologically relevant categories, and enables the identification of genes and pathways most significantly associated to each phenotypic group, while allowing for the participation of a given gene in more than one cluster. Genes assigned to each cluster are used for the detection of pathways predominantly activated in that cluster by finding statistically significant associated GO terms. We tested the approach with a published dataset of microarray experiments in yeast. Upon validation with the yeast dataset, we applied the technique to a prostate cancer dataset.

Results

Two major pathways are shown to be activated in organ-confined, non-metastatic prostate cancer: those regulated by the androgen receptor and by receptor tyrosine kinases. A number of gene markers (HER3, IQGAP2 and POR1) highlighted by the software and related to the later pathway have been validated experimentally a posteriori on independent samples.

Conclusion

Using a new microarray analysis tool followed by a posteriori experimental validation of the results, we have confirmed several putative markers of malignancy associated with peptide growth factor signalling in prostate cancer and revealed others, most notably ERRB3 (HER3). Our study suggest that, in primary prostate cancer, HER3, together or not with HER4, rather than in receptor complexes involving HER2, could play an important role in the biology of these tumors. These results provide new evidence for the role of receptor tyrosine kinases in the establishment and progression of prostate cancer.

AGR2, an androgen-inducible secretory protein overexpressed in prostate cancer

AGR2, the human homologue of Xenopus anterior gradient 2 (XAG2), was identified by a suppression subtractive hybridization-based technique as an androgen-inducible gene. There are two AGR2 transcripts, which encode the same secretory protein of 175 amino acids. The androgen induction was time- and dose-dependent, with more than a 10-fold increase in the level of AGR2 mRNA after 48 hr of treatment with 10(-9) M R1881. Expression of AGR2 mRNA was specifically detected in limited human tissue rich in epithelial cells, including the prostate gland. Analysis of 46 microdissected primary prostate adenocarcinoma samples showed that AGR2 mRNA expression was markedly elevated in the majority of tumors as compared to matched adjacent benign tissues. Androgen-induced AGR2 protein expression was demonstrated in LNCaP cells by Western blot analysis with an anti-AGR2 antibody. Immunohistochemistry analysis indicated that AGR2 protein expression was highly restricted to the secretory epithelial cells in the prostate gland. In tissue sections from radical prostatectomy specimens, immunohistochemical staining of AGR2 showed markedly increased expression in high-grade prostatic intraepithelial neoplasia and Gleason pattern 3-4 prostatic adenocarcinoma. Therefore, the androgen-induced secretory protein AGR2 may serve as a potential therapeutic target and/or molecular marker for prostate cancer.

Prostate-specific antigen screening in a high-risk population: Lessons from the community and how they relate to large-scale population-based studies

OBJECTIVES

To estimate the incidence of prostate cancer among African-American men and Caribbean immigrants to the United States, to assess the applicability of large-scale prostate screening trials to a community screening program, and to recruit unscreened men.

METHODS

African-American and Caribbean-American men were targeted with a community-based prostate cancer screening program in Jamaica, New York. Serum prostate-specific antigen determination and digital rectal examination were used to determine abnormal findings. The incidence of an abnormal screening examination was used to project the incidence of prostate cancer, which was compared with that in other reported trials.

RESULTS

The projected incidence of prostate cancer among African-Americans and Caribbean-Americans older than 50 years was 8% and 7%, respectively, similar to that reported in other trials of African-American men. The projected incidence of prostate cancer in Caribbean-American men aged 40 to 49 years was 1%, the same as the high rate reported among Caribbean men. As in other trials, a family history of prostate cancer and age were strong predictors of abnormal findings. Of the recruited men older than 50 years, 58% had never been screened compared with 42% nationally.

CONCLUSIONS

Large population-based screening trials have identified ethnic groups at high risk of prostate cancer. This trial detected high rates of abnormal screening findings by targeting ethnicity. The incidence of an abnormal examination was high in Caribbean-American men younger than 50 years old. Finally, this trial successfully recruited underscreened men.

Multiclass cancer classification and biomarker discovery using GA-based algorithms

MOTIVATION

The development of microarray-based high-throughput gene profiling has led to the hope that this technology could provide an efficient and accurate means of diagnosing and classifying tumors, as well as predicting prognoses and effective treatments. However, the large amount of data generated by microarrays requires effective reduction of discriminant gene features into reliable sets of tumor biomarkers for such multiclass tumor discrimination. The availability of reliable sets of biomarkers, especially serum biomarkers, should have a major impact on our understanding and treatment of cancer.

RESULTS

We have combined genetic algorithm (GA) and all paired (AP) support vector machine (SVM) methods for multiclass cancer categorization. Predictive features can be automatically determined through iterative GA/SVM, leading to very compact sets of non-redundant cancer-relevant genes with the best classification performance reported to date. Interestingly, these different classifier sets harbor only modest overlapping gene features but have similar levels of accuracy in leave-one-out cross-validations (LOOCV). Further characterization of these optimal tumor discriminant features, including the use of nearest shrunken centroids (NSC), analysis of annotations and literature text mining, reveals previously unappreciated tumor subclasses and a series of genes that could be used as cancer biomarkers. With this approach, we believe that microarray-based multiclass molecular analysis can be an effective tool for cancer biomarker discovery and subsequent molecular cancer diagnosis.

Tip110, the Human Immunodeficiency Virus Type 1 (HIV-1) Tat-interacting Protein of 110 kDa as a Negative Regulator of Androgen Receptor (AR) Transcriptional Activation

Upon binding to androgen, androgen receptor (AR) can activate expression of target genes through its direct binding to the androgen-responsive elements (AREs), which are located within the target gene promoters and/or enhancers. A number of cellular proteins have been identified as co-regulators to regulate this transactivation process. One common structural feature among these co-regulators is the presence of the LXXLL motif (X, any amino acid), the so-called nuclear receptor (NR) box, through which binding of these regulatory proteins to AR occurs. We have recently shown that Tip110 functions to potentiate the transactivation activity of human immunodeficiency virus type I (HIV-1) Tat protein. In this study, we report that Tip110 is a potent AR-binding protein that can suppress AR activity. Tip110 bound to AR in an NR box-dependent manner and inhibited AREs-mediated reporter gene expression. The inhibitory effects were abolished by removal of the NR box. Moreover, knock-down of the constitutive Tip110 expression significantly augmented AR transcriptional activation. In agreement with these findings, Tip110 overexpression blocked the prostate-specific antigen (PSA) gene, a well characterized target gene of AR from expression in LNCaP cells. Further analysis revealed that Tip110 prevented the complex formation between AR and AREs. Taken together, these results indicate that Tip110 is a negative regulator of AR transcriptional activation, and may be directly involved in AR-related developmental, physiological, and pathological processes.

Expression of Tip60, an androgen receptor coactivator, and its role in prostate cancer development

Prostate cancer (CaP) is initially androgen sensitive and responsive to hormone ablation therapy. However, cancer growth recurs despite androgen deprivation in the majority of cases of advanced disease. The molecular basis of this progression still remains unknown. The significance of androgen receptor (AR) coactivator proteins in this androgen-dependent malignancy is only beginning to emerge. In the present study, we examined the role of Tat interactive protein, 60 kDa (Tip60), an AR coactivator, in CaP progression. In hormone refractory CaP biopsies, we observed a nuclear accumulation of Tip60 expression in contrast to a more diffuse distribution pattern observed in benign prostate hyperplasia and primary CaP. Furthermore, in both the prostate xenograft model CWR22 and the LNCaP CaP cell line, we observed that androgen withdrawal promoted upregulation of Tip60 as well as nuclear accumulation. In contrast, androgen exposure resulted in decreased Tip60 expression that was more closely linked to a cytoplasmic presence. Chromatin immunoprecipitation analysis revealed Tip60's recruitment to the PSA gene promoter in both androgen-dependent and -independent cell lines. Thus, in vitro and in vivo data support a possible role for Tip60 in the molecular pathway leading to the development of androgen-independent CaP following long-term androgen deprivation therapy.

Cost-benefit analysis of total, free/total, and complexed prostate-specific antigen for prostate cancer screening

Refinements in prostate-specific antigen (PSA) through the use of its derivatives have augmented early detection rates of prostate cancer. However, these improvements are coupled with relatively large increases in unit cost per detected cancer. We used decision-analytic modeling to determine the most appropriate PSA derivative for population-based screening. We constructed a decision-analytic model to determine the PSA derivative with the highest cost-benefit ratio for prostate cancer screening. We defined 5 screening strategies: total PSA (tPSA) 4.0 ng/mL; free PSA/tPSA (f/tPSA) in conjunction with tPSA; and complexed PSA (cPSA) 3.8, 3.4, and 3.0 ng/mL. Prostate cancer prevalence, false-positive rates, and false-negative rates for each test strategy were calculated from a database of 2138 men. The direct costs were obtained from literature review and our department of clinical chemistry. The derivative cPSA with a positive threshold of 3.8 ng/mL was the dominant strategy. The average cost of screening was 138.93 dollars. The strategy of tPSA became dominant when the cost of cPSA was >35.00 dollars or the cost of a prostate biopsy was <67.30 dollars. To match the false-negative rate of tPSA 4.0 ng/mL, a cPSA threshold of 3.0 ng/mL is necessary (sensitivity 92.5%). At this level, the marginal cost increase over tPSA is 9.40 dollars. The dominant strategy for population-based prostate cancer screening is use of cPSA with a positive threshold of 3.8 ng/mL. The use of cPSA with a threshold of 3.0 ng/mL identifies a similar number of cancers with fewer biopsies than tPSA at 4.0 ng/mL.

Formation of the androgen receptor transcription complex

Androgen receptor (AR) is required for sexual differentiation and is implicated in the development of prostate cancer. Here we describe distinct functions for cofactor proteins and gene regulatory elements in the assembly of AR-mediated transcription complexes. The formation of an activation complex involves AR, coactivators, and RNA polymerase II recruitment to both the enhancer and promoter, whereas the formation of a repression complex involves factors bound only at the promoter and not the enhancer. These results suggest a model for the functional coordination between the promoter and enhancer in which communication between these elements is established through shared coactivators in the AR transcription complex.

Generation of CD4(+) and CD8(+) T lymphocyte responses by dendritic cells armed with PSA/anti-PSA (antigen/antibody) complexes

Dendritic cells (DC) acquire antigens through a number of cell surface structures including receptors for the Fc portion of immunoglobulins and mannose. Little is known about the effects of antigen uptake via these receptors on antigen processing and presentation. We compared the capacity of DC to generate CD4(+) and CD8(+) T cell responses after exposure to prostate-specific antigen (PSA) alone, PSA targeted to the mannose receptor (mannosylated PSA (PSA-m)), or PSA targeted to Fc receptors by combining PSA with an anti-PSA antibody (AR47.47). Autologous CD3(+) T cells were added to monocyte-derived immature DC that had been cultured with GM-CSF/IL-4 for 4 days, exposed to antigen, and matured with CD40L or TNFalpha/IFN-alpha. After several rounds of stimulation, T cell responses were assessed by intracellular IFN-gamma production using flow cytometry. Both CD4(+) and CD8(+) T cell responses were observed after stimulation with DC exposed to the PSA/anti-PSA complexes, whereas CD4(+) predominated over CD8(+) T cell responses after stimulation with PSA-armed DC or PSA-m. These CD8(+) T cells responded when rechallenged with DC pulsed with HLA allele-restricted PSA peptides. These results indicate that PSA and PSA-m are processed primarily through pathways that favor HLA Class II presentation, while the PSA/anti-PSA immune complexes are processed through both Class I and Class II pathways in monocyte-derived DC. These findings have potential applications in designing more effective cancer vaccines for prostate cancer.

Impact of preoperative serum PSA level from 0 to 10 ng/ml on pathological findings and disease-free survival after radical prostatectomy

BACKGROUND

To determine the impact of various preoperative serum prostate specific antigen (PSA) levels in the range from 0.1 to 10 ng/ml on pathological stage and disease-free survival after radical prostatectomy.

METHODS

We selected a cohort of 585 patients who underwent radical prostatectomy between 1991-1996 for clinically localized prostate cancer and presented with preoperative serum PSA levels from 0.1 to 10 ng/ml.

RESULTS

Pathological organ-confined disease was present in 57.6% of patients. The rate of organ-confined disease decreased from an average of 85% for patients with a PSA value < 2 ng/ml, to 46.8% for patients with a PSA value > 7 ng/ml. We found statistically significant correlations between preoperative serum PSA level and overall pathological stage (P = 0.001), pathologically organ-confined disease (P = 0.001), margin positive rates (P = 0.001), extra prostatic extension (P = 0.001), and seminal vesicle invasion (P = 0.001). The overall disease-free survival rate was 87%, with a median follow up of 42.4 months. Disease free survival was significantly better for patients with PSA up to 4 ng/ml (P = 0.005).

CONCLUSIONS

Our data suggests that PSA detection programs should strive to detect prostate cancer in men before the PSA level rises above 7 ng/ml. In addition, since patients with a PSA level < 4 ng/ml had better disease-free survival rates than those with a PSA level between 4.1-10 ng/ml, eliminating an arbitrary cutoff of 4 ng/ml, may lead to improved disease-free survival.

Complexed prostate-specific antigen improvement in detecting prostate cancer

This article presents the current reports of complexed prostate-specific antigen (PSA) aimed for the enhancement of prostate cancer detection. Further studies are needed to ascertain the variability of complexed PSA. Comparisons of percent free PSA, potential additive value of alpha(1)-antichymotripsin-bound PSA (PSA-ACT) and Bayer complexed PSA (cPSA) remains controversial in men with intermediate elevated total PSA concentration. Volume-referenced complexed PSA (PSA-ACT and cPSA) can enhance prostate cancer detection. Preliminary results show that PSA-alpha(2)-macrobloblin (PSA-a(2)M) and PSA-alpha(1)-protease inhibitor (PSA-API) are promising assays for improving cancer detection.