Apolipoprotein-D: a novel cellular marker for HGPIN and prostate cancer

The Lipocalin Apolipoprotein D Functional Portrait: A Systematic Review

Apolipoprotein D is a chordate gene early originated in the Lipocalin protein family. Among other features, regulation of its expression in a wide variety of disease conditions in humans, as apparently unrelated as neurodegeneration or breast cancer, have called for attention on this gene. Also, its presence in different tissues, from blood to brain, and different subcellular locations, from HDL lipoparticles to the interior of lysosomes or the surface of extracellular vesicles, poses an interesting challenge in deciphering its physiological function: Is ApoD a moonlighting protein, serving different roles in different cellular compartments, tissues, or organisms? Or does it have a unique biochemical mechanism of action that accounts for such apparently diverse roles in different physiological situations? To answer these questions, we have performed a systematic review of all primary publications where ApoD properties have been investigated in chordates. We conclude that ApoD ligand binding in the Lipocalin pocket, combined with an antioxidant activity performed at the rim of the pocket are properties sufficient to explain ApoD association with different lipid-based structures, where its physiological function is better described as lipid-management than by long-range lipid-transport. Controlling the redox state of these lipid structures in particular subcellular locations or extracellular structures, ApoD is able to modulate an enormous array of apparently diverse processes in the organism, both in health and disease. The new picture emerging from these data should help to put the physiological role of ApoD in new contexts and to inspire well-focused future research.

Based on biomedical index data: Risk prediction model for prostate cancer

ABSTRACT

To explore the influencing factors of prostate cancer occurrence, set up risk prediction model, require reference for the preliminary diagnosis of clinical doctors, this model searched database through the data of prostate cancer patients and prostate hyperplasia patients National Clinical Medical Science Data Center.With the help of Stata SE 12.0 and SPSS 25.0 software, the biases between groups were balanced by propensity score matching. Based on the matched data, the relevant factors were further screened by stepwise logistic regression analysis, the key variable and artificial neural network model are established. The prediction accuracy of the model is evaluated by combining the probability of test set with the area under receiver operating characteristic curve (ROC).After 1:2 PSM, 339 pairs were matched successfully. There are 159 cases in testing groups and 407 cases in training groups. And the regression model was P = 1 / (1 + e (0.122 ∗ age + 0.083 ∗ Apo lipoprotein C3 + 0.371 ∗ total prostate specific antigen (tPSA) -0.227 ∗ Apo lipoprotein C2-6.093 ∗ free calcium (iCa) + 0.428 ∗ Apo lipoprotein E-1.246 ∗ triglyceride-1.919 ∗ HDL cholesterol + 0.083 ∗ creatine kinase isoenzyme [CKMB])). The logistic regression model performed very well (ROC, 0.963; 95% confidence interval, 0.951 to 0.978) and artificial neural network model (ROC, 0.983; 95% confidence interval, 0.964 to 0.997). High degree of Apo lipoprotein E (Apo E) (Odds Ratio, [OR], 1.535) in blood test is a risk factor and high triglyceride (TG) (OR, 0.288) is a protective factor.It takes the biochemical examination of the case as variables to establish a risk prediction model, which can initially reflect the risk of prostate cancer and bring some references for diagnosis and treatment.

Comprehensive analysis of tumor mutation burden and immune microenvironment in gastric cancer

Tumor mutation burden (TMB) was a promising marker for immunotherapy. We aimed to investigate the prognostic role of TMB and its relationship with immune cells infiltration in gastric cancer (GC). We analyzed the mutation landscape of all GC cases and TMB of each GC patient was calculated and patients were divided into TMB-high and TMB-low group. Differentially expressed genes (DEGs) between the two groups were identified and pathway analysis was performed. The immune cells infiltration in each GC patient was evaluated and Kaplan-Meier analysis was performed to investigate the prognostic role of immune cells infiltration. At last, hub immune genes were identified and a TMB prognostic risk score (TMBPRS) was constructed to predict the survival outcome of GC patients. The relationships between mutants of hub immune genes and immune infiltration level in GC was investigated. We found higher TMB was correlated with better survival outcome and female patients, patients with T1-2 and N0 had higher TMB score. Altogether 816 DEGs were harvested and pathway analysis demonstrated that patients in TMB-high group were associated with neuroactive ligand-receptor interaction, cAMP signaling pathway, calcium signaling pathway. The infiltration of activated CD4+ memory T cells, follicular helper T cells, resting NK cells, M0 and M1 macrophages and neutrophils in TMB-high group were higher compared than that in TMB-low group and high macrophage infiltration was correlated with inferior survival outcome of GC patients. Lastly, the TMBPRS was constructed and GC patients with high TMBPRS had poor prognosis.

Apolipoprotein D

ApoD is a 25 to 30 kDa glycosylated protein, member of the lipocalin superfamily. As a transporter of several small hydrophobic molecules, its known biological functions are mostly associated to lipid metabolism and neuroprotection. ApoD is a multi-ligand, multi-function protein that is involved lipid trafficking, food intake, inflammation, antioxidative response and development and in different types of cancers. An important aspect of ApoD's role in lipid metabolism appears to involve the transport of arachidonic acid, and the modulation of eicosanoid production and delivery in metabolic tissues. ApoD expression in metabolic tissues has been associated positively and negatively with insulin sensitivity and glucose homeostasis in a tissue dependent manner. ApoD levels rise considerably in association with aging and neuropathologies such as Alzheimer's disease, stroke, meningoencephalitis, moto-neuron disease, multiple sclerosis, schizophrenia and Parkinson's disease. ApoD is also modulated in several animal models of nervous system injury/pathology.

Mass Spectrometry Reveals New Insights into the Production of Superoxide Anions and 4-Hydroxynonenal Adducted Proteins in Human Sperm

The free-radical theory of male infertility suggests that reactive oxygen species produced by the spermatozoa themselves are a leading cause of sperm dysfunction, including loss of sperm motility. However, the field is overshadowed on several fronts, primarily because: i) the probes used to measure reactive oxygen species (ROS) are imprecise; and ii) many reports suggesting that oxygen radicals are detrimental to sperm function add an exogenous source of ROS. Herein, a more reliable approach to measure superoxide anion production by human spermatozoa based on MS analysis is used. Furthermore, the formation of the lipid-peroxidation product 4-hydroxynonenal (4-HNE) during in vitro incubation using proteomics is also investigated. The data demonstrate that neither superoxide anion nor other free radicals that cause 4-HNE production are related to the loss of sperm motility during incubation. Interestingly, it appears that many of the 4-HNE adducted proteins, found within spermatozoa, originate from the prostate. A quantitative SWATH analysis demonstrate that these proteins transiently bind to sperm and are then shed during in vitro incubation. These proteomics-based findings propose a revised understanding of oxidative stress within the male reproductive tract.

Apolipoproteins and cancer

The role of apolipoproteins in cardiovascular disease has been well investigated, but their participation in cancer has only been explored in a few published studies which showed a close link with certain kinds of cancer. In this review, we focused on the function of different kinds of apolipoproteins in cancers, autophagy, oxidative stress, and drug resistance. The potential application of apolipoproteins as biomarkers for cancer diagnosis and prognosis was highlighted, together with an investigation of their potential as drug targets for cancer treatment. Many important roles of apolipoproteins and their mechanisms in cancers were reviewed in detail and future perspectives of apolipoprotein research were discussed.

Serum and tissue proteomic signatures of patients with hepatocellular carcinoma using 2‑D gel electrophoresis

Hepatocellular carcinoma (HCC) accounts for ~85% of primary liver cancer cases and is a leading cause of mortality worldwide. Effective early diagnosis is difficult for HCC; however, effective biomarkers may be beneficial for diagnosis. In the current study, serum samples, and HCC and adjacent tissue samples were obtained from patients with HCC for the detection of biomarkers using 2-D gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight (TOF)/TOF mass spectrometry. The crude serum samples did not need to be prepared for removal of high abundance proteins. The mRNA expression levels of HCC-associated proteins were detected in tissues using reverse transcription-quantitative PCR. Statistical analysis and database matching were used to identify the differentially expressed proteins detected in the serum and tissue groups. Immunohistochemistry (IHC) was performed to detect the expression of significant proteins in HCC and adjacent tissues. The results revealed ~800 protein spots on a 2-DE gel that were detected in serum samples, and 1,200 spots were identified in the tissue samples. The protein and mRNA expression levels of oxysterol binding protein-like 11 (OSBPL11) in HCC serum and tissue samples were consistent. Pathway analysis demonstrated that members of the apolipoprotein family, particularly apolipoprotein E (APOE), and RAS family members were closely associated in HCC, either directly or via ferratin heavy polypeptide 1. IHC results demonstrated that the APOE protein serves an important role in liver cancer development. The lysis buffer used in the current study was effective for serum protein separation in 2-DE sample preparation. In addition, the present study revealed that downregulated OSBPL11 may be a potential indicator for HCC, and the apolipoprotein family, particularly APOE, and the RAS family may cooperatively serve an important role.

Production of a soluble and functional recombinant apolipoproteinD in the Pichia pastoris expression system

ApolipoproteinD (ApoD) is a human glycoprotein from the lipocalin family. ApoD contains a conserved central motif of an 8-stranded antiparallel β-sheet, which forms a beta-barrel that can be used for transport and storage of diverse hydrophobic ligands. Due to hydrophobic nature of ApoD, it has been difficult to generate a recombinant version of this protein. In the present work, we aimed at the production of ApoD in the robust Pichia pastoris expression system. To this end, the ApoD gene sequence was synthesized and subcloned for expression in the yeast host cells. Following integration of the ApoD gene into the yeast genomic region using homologous recombination, the ApoD recombinant protein was induced using methanol, reaching its maximum induction at 96 h. Having purified the ApoD recombinant protein by affinity chromatography, we measured the dissociation constant (KD) using its natural ligands: progesterone and arachidonic acid. Our results provide a viable solution to the production of recombinant ApoD protein in lieu of previous obstacles in generating soluble and functional ApoD protein.

The menagerie of human lipocalins: a natural protein scaffold for molecular recognition of physiological compounds

While immunoglobulins are well-known for their characteristic ability to bind macromolecular antigens (i.e., as antibodies during an immune response), the lipocalins constitute a family of proteins whose role is the complexation of small molecules for various physiological processes. In fact, a number of low-molecular-weight substances in multicellular organisms show poor solubility, are prone to chemical decomposition, or play a pathophysiological role and thus require specific binding proteins for transport through body fluids, storage, or sequestration. In many cases, lipocalins are involved in such tasks. Lipocalins are small, usually monomeric proteins with 150-180 residues and diameters of approximately 40 Å, adopting a compact fold that is dominated by a central eight-stranded up-and-down β-barrel. At the amino-terminal end, this core is flanked by a coiled polypeptide segment, while its carboxy-terminal end is followed by an α-helix that leans against the β-barrel as well as an amino acid stretch in a more-or-less extended conformation, which finally is fixed by a disulfide bond. Within the β-barrel, the antiparallel strands (designated A to H) are arranged in a (+1)7 topology and wind around a central axis in a right-handed manner such that part of strand A is hydrogen-bonded to strand H again. Whereas the lower region of the β-barrel is closed by short loops and densely packed hydrophobic side chains, including many aromatic residues, the upper end is usually open to solvent. There, four long loops, each connecting one pair of β-strands, together form the entrance to a cup-shaped cavity. Depending on the individual structure of a lipocalin, and especially on the lengths and amino acid sequences of its four loops, this pocket can accommodate chemical ligands of various sizes and shapes, including lipids, steroids, and other chemical hormones as well as secondary metabolites such as vitamins, cofactors, or odorants. While lipocalins are ubiquitous in all higher organisms, physiologically important members of this family have long been known in the human body, for example with the plasma retinol-binding protein that serves for the transport of vitamin A. This prototypic human lipocalin was the first for which a crystal structure was solved. Notably, several other lipocalins were discovered and assigned to this protein class before the term itself became familiar, which explains their diverse names in the scientific literature. To date, up to 15 distinct members of the lipocalin family have been characterized in humans, and during the last two decades the three-dimensional structures of a dozen major subtypes have been elucidated. This Account presents a comprehensive overview of the human lipocalins, revealing common structural principles but also deviations that explain individual functional features. Taking advantage of modern methods for combinatorial protein design, lipocalins have also been employed as scaffolds for the construction of artifical binding proteins with novel ligand specificities, so-called Anticalins, hence opening perspectives as a new class of biopharmaceuticals for medical therapy.

Shotgun proteomic analysis of plasma from dairy cattle suffering from footrot: characterization of potential disease-associated factors

The plasma proteome of healthy dairy cattle and those with footrot was investigated using a shotgun LC-MS/MS approach. In total, 648 proteins were identified in healthy plasma samples, of which 234 were non-redundant proteins and 123 were high-confidence proteins; 712 proteins were identified from footrot plasma samples, of which 272 were non-redundant proteins and 138 were high-confidence proteins. The high-confidence proteins showed significant differences between healthy and footrot plasma samples in molecular weight, isoelectric points and the Gene Ontology categories. 22 proteins were found that may differentiate between the two sets of plasma proteins, of which 16 potential differential expression (PDE) proteins from footrot plasma involved in immunoglobulins, innate immune recognition molecules, acute phase proteins, regulatory proteins, and cell adhesion and cytoskeletal proteins; 6 PDE proteins from healthy plasma involved in regulatory proteins, cytoskeletal proteins and coagulation factors. Of these PDE proteins, haptoglobin, SERPINA10 protein, afamin precursor, haptoglobin precursor, apolipoprotein D, predicted peptidoglycan recognition protein L (PGRP-L) and keratan sulfate proteoglycan (KS-PG) were suggested to be potential footrot-associated factors. The PDE proteins PGRP-L and KS-PG were highlighted as potential biomarkers of footrot in cattle. The resulting protein lists and potential differentially expressed proteins may provide valuable information to increase understanding of plasma protein profiles in cattle and to assist studies of footrot-associated factors.

Apolipoprotein A1: A new serum marker correlated to JAK2 V617F proportion at diagnosis in patients with polycythemia vera

Polycythemia vera (PV) is a myeloproliferative disorder (MPD) characterized by an acquired gain-of-function mutation of the JAK2 protein (JAK2 V617F). Allele-specific quantitative PCR has showed a JAK2 V617F dosage effect on haematological and clinical parameters of PV at diagnosis, but it is unknown whether the level of certain serum proteins might correlate with the proportion of mutated JAK2. Taking into account that such proteins could represent useful prognostic marker, we investigated the serum protein profile of PV patients by SELDI-TOF MS. We identified apolipoprotein A1 (Apo-A1) as a serum marker correlated to the percentage of JAK2 V617F alleles; Apo-A1 expression being the highest for PV patients with more than 75% of mutated alleles. Immuno-assay on an automated random immuno-analyser confirmed the correlation between Apo-A1 concentrations and JAK2 V617F percentages, and showed that serum Apo-A1 assay allowed the specific discrimination of PV patients with high levels of mutated alleles (≥75%). These data suggest that Apo-A1 assay could be a useful assay for the stratification of PV patients at diagnosis.

Precursors of prostate cancer

High-grade prostatic intraepithelial neoplasia (PIN) is the only accepted precursor of prostatic adenocarcinoma, according to numerous studies of animal models and man; other proposed precursors include atrophy and malignancy-associated changes (with no morphologic changes). PIN is characterized by progressive abnormalities of phenotype and genotype that are intermediate between benign prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of prostatic carcinogenesis. The only method of detection of PIN is biopsy because it does not significantly elevate serum prostate-specific antigen concentration and cannot be detected by ultrasonography. The mean incidence of PIN in biopsies is 9% (range, 4%-16%), representing about 115,000 new cases of isolated PIN diagnosed each year in the United States. The clinical importance of PIN is its high predictive value as a marker for adenocarcinoma, and its identification warrants repeat biopsy for concurrent or subsequent carcinoma, especially when multifocal or observed in association with atypical small acinar proliferation (ASAP). Carcinoma develops in most patients with PIN within 10 years. Androgen deprivation therapy and radiation therapy decrease the prevalence and extent of PIN, suggesting that these forms of treatment may play a role in prevention of subsequent cancer. Multiple clinical trials to date of men with PIN have had modest success in delaying or preventing subsequent cancer.

Increased JNK1 activity contributes to the upregulation of ApoD in the apocrine secretory gland cells from axillary osmidrosis

Axillary osmidrosis is a benign disorder that causes functional and emotional problems in Asian patients. Recently, ApoD has been identified as an axillary odorant binding protein. The present study was designed to compare the expression of ApoD in normal and osmidrosis subjects. Compared with the normal subjects, osmidrosis subjects had a higher expression of AR and ApoD in the apocrine samples, both at mRNA and protein level. Further study showed that, consistent with the increased ApoD and AR, phosphorylated JNK1 was higher in apocrine samples from axillary osmidrosis subjects, while with no obvious differences of the total expression of JNK1. In the cultured apocrine epithelial cells from normal subjects, 5α-dihydrotestosterone (5α-DHT) increased the expression of ApoD in a dose dependent manner, which can be inhibited by the JNK1 inhibitor. In contrast, in the cultured apocrine epithelial cells from axillary osmidrosis subjects, inhibition of JNK1 significantly reduced the expression of ApoD. Taken together, our study here revealed that increased JNK1 activation in the apocrine cells from axillary osmidrosis contributes to the increased ApoD expression, which in turn involved in the process of axillary osmidrosis.

Stromal activation associated with development of prostate cancer in prostate-targeted fibroblast growth factor 8b transgenic mice

Expression of fibroblast growth factor 8 (FGF-8) is commonly increased in prostate cancer. Experimental studies have provided evidence that it plays a role in prostate tumorigenesis and tumor progression. To study how increased FGF-8 affects the prostate, we generated and analyzed transgenic (TG) mice expressing FGF-8b under the probasin promoter that targets expression to prostate epithelium. Prostates of the TG mice showed an increased size and changes in stromal and epithelial morphology progressing from atypia and prostatic intraepithelial neoplasia (mouse PIN, mPIN) lesions to tumors with highly variable phenotype bearing features of adenocarcinoma, carcinosarcoma, and sarcoma. The development of mPIN lesions was preceded by formation of activated stroma containing increased proportion of fibroblastic cells, rich vasculature, and inflammation. The association between advancing stromal and epithelial alterations was statistically significant. Microarray analysis and validation with quantitative polymerase chain reaction revealed that expression of osteopontin and connective tissue growth factor was markedly upregulated in TG mouse prostates compared with wild type prostates. Androgen receptor staining was decreased in transformed epithelium and in hypercellular stroma but strongly increased in the sarcoma-like lesions. In conclusion, our data demonstrate that disruption of FGF signaling pathways by increased epithelial production of FGF-8b leads to strongly activated and atypical stroma, which precedes development of mPIN lesions and prostate cancer with mixed features of adenocarcinoma and sarcoma in the prostates of TG mice. The results suggest that increased FGF-8 in human prostate may also contribute to prostate tumorigenesis by stromal activation.

Comparative biomarker expression and RNA integrity in biospecimens derived from radical retropubic and robot-assisted laparoscopic prostatectomies

BACKGROUND

Knowledge of preanalytic conditions that biospecimens are subjected to is critically important because novel surgical procedures, tissue sampling, handling, and storage might affect biomarker expression or invalidate tissue samples as analytes for some technologies.

METHODS

We investigated differences in RNA quality, gene expression by quantitative real-time PCR, and immunoreactive protein expression of selected prostate cancer biomarkers between tissues from retropubic radical prostatectomy (RRP) and robot-assisted laparoscopic prostatectomy (RALP). Sections of tissue microarray of 23 RALP and 22 RRP samples were stained with antibodies to androgen receptor (AR) and prostate-specific antigen (PSA) as intersite controls, and 14 other candidate biomarkers of research interest to three laboratories within the Australian Prostate Cancer BioResource tissue banking network. Quantitative real-time PCR was done for AR, PSA (KLK3), KLK2, KLK4, and HIF1A on RNA extracted from five RALP and five RRP frozen tissue cores.

RESULTS

No histologic differences were observed between RALP and RRP tissue. Biomarker staining grouped these samples into those with increased (PSA, CK8/18, CKHMW, KLK4), decreased (KLK2, KLK14), or no change in expression (AR, ghrelin, Ki67, PCNA, VEGF-C, PAR2, YB1, p63, versican, and chondroitin 0-sulfate) in RALP compared with RRP tissue. No difference in RNA quality or gene expression was detected between RALP and RRP tissue.

CONCLUSIONS

Changes in biomarker expression between RALP and RRP tissue exist at the immunoreactive protein level, but the etiology is unclear.

IMPACT

Future studies should account for changes in biomarker expression when using RALP tissues, and mixed cohorts of RALP and RRP tissue should be avoided.

The isolation and identification of apolipoprotein C-I in hormone-refractory prostate cancer using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Androgens play a central role in prostate cancer pathogenesis, and hence most of the patients respond to androgen deprivation therapies. However, patients tend to relapse with aggressive prostate cancer, which has been termed as hormone refractory. To identify the proteins that mediate progression to the hormone-refractory state, we used protein-chip technology for mass profiling of patients' sera. This study included 16 patients with metastatic hormone-refractory prostate cancer who were initially treated with androgen deprivation therapy. Serum samples were collected from each patient at five time points: point A, pre-treatment; point B, at the nadir of the prostate-specific antigen (PSA) level; point C, PSA failure; point D, the early hormone-refractory phase; and point E, the late hormone-refractory phase. Using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry, we performed protein mass profiling of the patients' sera and identified a 6 640-Da peak that increased with disease progression. Target proteins were partially purified, and by amino acid sequencing the peak was identified as a fragment of apolipoprotein C-I (ApoC-I). Serum ApoC-I protein levels increased with disease progression. On immunohistochemical analysis, the ApoC-I protein was found localized to the cytoplasm of the hormone-refractory cancer cells. In this study, we showed an increase in serum ApoC-I protein levels in prostate cancer patients during their progression to the hormone-refractory state, which suggests that ApoC-I protein is related to progression of prostate cancer. However, as the exact role of ApoC-I in prostate cancer pathogenesis is unclear, further research is required.

A proteomics approach to identify changes in protein profiles in serum of Familial Adenomatous Polyposis patients

Familial adenomatous polyposis (FAP) is one of the most important clinical hereditary forms of inherited susceptibility to colorectal cancer and is characterized by a high degree of phenotypic heterogeneity. We used a mass spectrometry driven-proteomic strategy to identify serum molecules differently expressed in FAP patients. The data obtained were subsequently processed by bioinformatic analysis and confirmed by Western blotting. Significant differences were highlighted in the expression of serum proteins of FAP patients. In particular, two proteins (alpha-2-HS-glycoprotein and apoliprotein D) were down-regulated (about 0.5- and 0.7-fold, respectively) in carpeting versus diffuse FAP patients and healthy donors, while alpha-2-antiplasmin was up-regulated (about 1.4-fold). Moreover, mass spectrometry approach enabled us to identify serum biomarkers specific for two distinct clinical form of FAP, i.e. carpeting and diffuse FAP. In particular, vitronectin was up-regulated (more than 1.4-fold) in diffuse FAP patients versus carpeting FAP and versus healthy donors, and two additional proteins (Haptoglobin and alpha-1-acid glycoprotein 1) were up-regulated in 2 out of 3 carpeting FAP patients. Our study suggests that mass spectrometry combined to a strong bioinformatics analysis is a valuable tool for the identification of quali/quantitative differences in the serum proteome of otherwise indistinguishable FAP phenotypes. Moreover, the definition of a proteomic profile, supported by the supervised classification, is a powerful and highly sensitive approach for the identification molecular signatures that are able to outperform the traditional disease markers and can therefore be efficiently applied for the diagnosis and clinical management of FAP patients.

Genetic background influences murine prostate gene expression: implications for cancer phenotypes

Microarray analyses to quantitate transcript levels in the prostates of five inbred mouse strains identified differences in gene expression in benign epithelium that correlated with the differentiation state of adjacent tumors.

Background

Cancer of the prostate is influenced by both genetic predisposition and environmental factors. The identification of genes capable of modulating cancer development has the potential to unravel disease heterogeneity and aid diagnostic and prevention strategies. To this end, mouse models have been developed to isolate the influences of individual genetic lesions in the context of consistent genotypes and environmental exposures. However, the normal prostatic phenotypic variability dictated by a genetic background that is potentially capable of influencing the process of carcinogenesis has not been established.

Results

In this study we used microarray analysis to quantify transcript levels in the prostates of five commonly studied inbred mouse strains. We applied a multiclass response t-test and determined that approximately 13% (932 genes) exhibited differential expression (range 1.3-190-fold) in any one strain relative to other strains (false discovery rate ≤10%). Expression differences were confirmed by quantitative RT-PCR, or immunohistochemistry for several genes previously shown to influence cancer progression, such as Psca, Mmp7, and Clusterin. Analyses of human prostate transcripts orthologous to variable murine prostate genes identified differences in gene expression in benign epithelium that correlated with the differentiation state of adjacent tumors. For example, the gene encoding apolipoprotein D, which is known to enhance resistance to cell stress, was expressed at significantly greater levels in benign epithelium associated with high-grade versus low-grade cancers.

Conclusion

These studies support the concept that the cellular, tissue, and organismal context contribute to oncogenesis and suggest that a predisposition to a sequence of events leading to pathology may exist prior to cancer initiation.

Contemporary clinical management of isolated high-grade prostatic intraepithelial neoplasia

High-grade prostatic intraepithelial neoplasia (HGPIN) is a premalignant lesion associated with increased risk of coexistent cancer or delayed progression to carcinoma. Extended biopsy schemes have improved the ability to rule out concurrent cancers, increased the detection of isolated HGPIN and removed the routine necessity for immediate repeat biopsy. As the natural history of HGPIN is poorly defined, and no non-invasive marker allows monitoring of progression to cancer, routine delayed interval biopsy should be considered in all patients. In this article, we present an overview of the existing literature on HGPIN and a proposed strategy for clinical management.

Structural Insight into the Dual Ligand Specificity and Mode of High Density Lipoprotein Association of Apolipoprotein D

Human apolipoprotein D (ApoD) occurs in plasma associated with high density lipoprotein. Apart from the involvement in lipid metabolism, its binding activity for progesterone and arachidonic acid plays a role in cancer development and neurological diseases. The crystal structures of free ApoD and its complex with progesterone were determined at 1.8A resolution and reveal a lipocalin fold. The narrow, mainly uncharged pocket within the typical beta-barrel accommodates progesterone with its acetyl side chain oriented toward the bottom. The cavity adopts essentially the same shape in the absence of progesterone and allows complexation of arachidonic acid as another cognate ligand. Three of the four extended loops at the open end of the beta-barrel expose hydrophobic side chains, which is an unusual feature for lipocalins and probably effects association with the high density lipoprotein particle by mediating insertion into the lipid phase. This mechanism is in line with an unpaired Cys residue in the same surface region that can form a disulfide cross-link with apolipoprotein A-II.

Prostate stem cell antigen (PSCA) mRNA expression in prostatic intraepithelial neoplasia: implications for the development of prostate cancer

BACKGROUND

Prior data clearly demonstrated the expression of prostate stem cell antigen (PSCA) mRNA in prostatic intraepithelial neoplasia (PIN) tissues. The purpose of the present investigation was to determine whether PSCA mRNA expression was associated with the presence of cancer in this disease.

METHODS

One hundred seventeen men were diagnosed with isolated PIN on initial prostate biopsy, 51 with low-grade form (LGPIN), and 66 with high-grade form (HGPIN). PSCA mRNA expression in initial PIN and subsequent cancer was examined by in situ hybridization (ISH). The differences of the PSCA mRNA expression level between the groups were analyzed by the Chi-square and Student's t-test. Univariate and multivariate logistic regression analyses were performed to evaluate the predictive performance of PSCA mRNA.

RESULTS

PSCA mRNA expression level in 34 subsequent cancers was statistically increased compared with their paired PIN (P < 0.001), with a Gleason's dependence. HGPIN showed statistically high PSCA mRNA expression compared with LGPIN (P < 0.01). PSCA mRNA expression levels were significantly stronger in the initial isolated LGPIN and isolated HGPIN with subsequent cancer than those without (P < 0.001 and P < 0.001, respectively). Multivariate logistic regression analysis demonstrated that only PSCA mRNA was predictive of the onset of subsequent cancer in patients with isolated LGPIN and in those with isolated HGPIN, respectively.

CONCLUSIONS

Our data identify PSCA mRNA in initial PIN as a significant predictor of subsequent cancer, suggesting that PSCA implies in prostatic tumorigenesis and may be used to identify the patients with isolated PIN who are at high risk for cancer onset in the disease process.

Solubility engineering and crystallization of human apolipoprotein D

Human apolipoprotein D (ApoD) is a physiologically important member of the lipocalin protein family that was discovered as a peripheral subunit of the high-density lipoprotein (HDL) but is also abundant in other body fluids and organs, including neuronal tissue. Although it has been possible to produce functional ApoD in the periplasm of Escherichia coli and to demonstrate its ligand-binding activity for progesterone and arachidonic acid, the recombinant protein suffers from a pronounced tendency to aggregate and to adsorb to vessel surfaces as well as chromatography matrices, thus hampering further structural investigation. Here, we describe a systematic mutagenesis study directed at presumably exposed hydrophobic side chains of the unglycosylated recombinant protein. As a result, one ApoD mutant with just three new amino acid substitutions--W99H, I118S, and L120S--was identified, which exhibits the following features: (1) improved yield upon periplasmic biosynthesis in E. coli, (2) elution as a monomeric protein from a gel permeation chromatography column, and (3) unchanged binding activity for its physiological ligands. In addition, the engineered ApoD was successfully crystallized (space group I4 with unit cell parameters a = 75.1 A, b = 75.1 A, c = 166.0 A, alpha = beta = gamma = 90 degrees), thus demonstrating its conformationally homogeneous behavior and providing a basis for the future X-ray structural analysis of this functionally still puzzling protein.