Antiprostasome antibodies: possible serum markers for prostate cancer metastasizing liability

Annexin A3, a Calcium-Dependent Phospholipid-Binding Protein: Implication in Cancer

Annexin A3 (ANXA3), also known as lipocortin III and placental anticoagulant protein III, has been reported to be dysregulated in tumor tissues and cancer cell lines, and harbors pronounced diagnostic and prognostic value for certain malignancies, such as breast, prostate, colorectal, lung and liver cancer. Aberrant expression of ANXA3 promotes tumor cell proliferation, invasion, metastasis, angiogenesis, and therapy resistance to multiple chemotherapeutic drugs including platinum-based agents, fluoropyrimidines, cyclophosphamide, doxorubicin, and docetaxel. Genetic alterations on the ANXA3 gene have also been reported to be associated with the propensity to form certain inherited, familial tumors. These diverse functions of ANXA3 in tumors collectively indicate that ANXA3 may serve as an attractive target for novel anticancer therapies and a powerful diagnostic and prognostic biomarker for early tumor detection and population risk screening. In this review, we dissect the role of ANXA3 in cancer in detail.

High expression of tumor susceptibility gene 101 (TSG101) is associated with more aggressive behavior in colorectal carcinoma

INTRODUCTION

Identification of genetic determinants such as exosomal content that drives progression and metastasis of colorectal cancer (CRC) has received considerable attention. The present study aims to identify a suitable biomarker in CRC tissues and exosomes based on bioinformatics data to evaluate its expression patterns in CRC tissues as well as its clinicopathological significance.

MATERIALS AND METHODS

Protein-protein interaction (PPI) network and enrichment analysis were applied to identify up-regulated genes that contributed in CRC exosomes to select the marker. The expression patterns and clinical significance of selected exosomal marker were evaluated in tissue microarrays (TMAs) of 445 CRC tumors and 39 adjacent normal tissues using immunohistochemistry method.

RESULTS

Based on bioinformatics data, TSG101 gene was prominent amongst the tumor tissues and exosomes. Expression of TSG101 was significantly up-regulated in tumor cells compared to adjacent normal tissues (p-value = 0.04). Moreover, higher expressions of TSG101 (cytoplasmic and nuclear) were significantly associated with tumor differentiation (p-value = 0.042) and distant metastasis (p-value = 0.027). A significant association was found in the cytoplasmic expression of TSG101 between well and moderate tumor differentiation (p-value = 0.005) as well as moderate and poor differentiation (p-value = 0.050).

CONCLUSION

These findings indicate that the exploration of crosstalk between exosome content and CRC may be valuable for the development of novel exosomal biomarkers. Increased expression of TSG101, as a promising exosome marker, is more associated with more aggressive tumor behaviors, metastasis, and progression of CRC, which paves the way for therapeutic strategies and CRC management. However, further investigations are warranted to clarify the molecular mechanisms of TSG101 in CRC.

Human prostasomes an extracellular vesicle - Biomarkers for male infertility and prostrate cancer: The journey from identification to current knowledge

Extracellular vesicles (EVs) are gaining attention among the cell biologists and researchers over the last two decades. Prostasomes are considered to be (Evs) secreted by prostate epithelial cells into the semen during emission or ejaculation. Prostasomes contain various proteins required for immune regulation namely, amino and dipeptidyl peptidase; endopeptidase (neutral); decay accelerating factor; angiotensin-converting enzyme. Sperm cells need a few prerequisites in order to fertilize the egg. The role of prostasomes in enhancing the male fertility was reviewed extensively throughout the manuscript. Also, prostasomes have an immunosuppressive, immunomodulatory, antibacterial role in the female reproductive tract, and in some cases they can be used as immunocontraceptive agent to regulate the fertility status. This review will give insights to many active researchers in the field of prostasomal research and male infertility/fertility research. This review will open many unanswered mechanisms of prostasomes with respect to structure-function analysis, fatty acids patterns in diagnosis as well as prognosis of male infertility/fertility. More scientific reports are in need to support the mechanism of prostasomes and its role in immunomodulation. The development of prostasomes as a biomarker for the prostate cancer is still miserable with a lot of controversial results by various researchers.

Prostasomes as a source of diagnostic biomarkers for prostate cancer

New biomarkers are needed to improve the diagnosis of prostate cancer. Similarly to healthy cells, prostate epithelial cancer cells produce extracellular vesicles (prostasomes) that can be isolated from seminal fluid, urine, and blood. Prostasomes contain ubiquitously expressed and prostate-specific membrane and cytosolic proteins, as well as RNA. Both quantitative and qualitative changes in protein, mRNA, long noncoding RNA, and microRNA composition of extracellular vesicles isolated from prostate cancer patients have been reported. In general, however, the identified extracellular vesicle-associated single-marker molecules or combinations of marker molecules require confirmation in large cohorts of patients to validate their specificity and sensitivity as prostate cancer markers. Complications include variable factors such as prostate manipulation and urine flux, as well as masking by ubiquitously expressed free molecules and extracellular vesicles from tissues other than the prostate. Herein, we propose that the most promising methods include comprehensive combinational screening for (mutant) RNA in prostasomes that are immunoisolated with antibodies targeting prostate-specific epitopes.

Predicting the risk of bone metastasis in prostate cancer

The ability to identify prostate cancer patients at 'high risk' for bone metastasis development could allow early selection of those most likely to benefit from interventions to prevent or delay bone metastasis. This review is aimed to identify potential predictors of risk for bone metastasis in newly diagnosed patients and in those who have already received treatment. At diagnosis, established predictors of prostate cancer aggressiveness (e.g. PSA level, clinical stage, Gleason score) can identify patients at risk for bone metastasis. Following treatment of the disease, increasing evidence suggests that absolute PSA levels and other measures of PSA kinetics are useful to aid prediction of bone metastasis risk in patients both with and without a history of ADT. However, which PSA parameter most accurately predicts risk and the cut-off values that should be employed are unclear. Inclusion of PSA parameters to identify a high risk population may be beneficial in whom bone-modifying treatments are being considered. Other novel (but unvalidated) biomarkers that potentially predict the development of bone metastases have been identified, although it is unclear whether they will have value as independent markers or when combined with other parameters (e.g. measures of PSA kinetics). Further prospective studies of PSA kinetics and other predictive markers are, therefore, required to define the optimal criteria for identifying patients at high risk of bone metastases and those who are most likely to benefit from intensive monitoring and therapeutic intervention.

Local radiotherapy increases the level of autoantibodies to ribosomal P0 protein but not to heat shock proteins, extracellular matrix molecules and EGFR/ErbB2 receptors in prostate cancer patients

Prostate cancer is a common cancer among men in developed countries. Although hormonotherapy and radiotherapy (RT) represent valid therapies for prostate cancer treatment, novel immunological approaches have been explored. The development of clinical trials employing cancer vaccines has indicated that immune response to tumor antigens can be boosted and that vaccine administration can improve patient survival. Immune response to tumor antigens could also be enhanced after standard therapies. In the present study, we determined the occurrence of antibodies to extracellular matrix (ECM) molecules, heat shock protein (HSP), ribosomal P0 protein, EGFR, ErbB2 and prostate-specific antigen (PSA) in 35 prostate cancer patients prior to and following local RT and hormonotherapy. We demonstrated that immunity to P0, ECM molecules [collagens (C) CI, CIII, CV, fibronectin (FN) and laminin (LM)] and to HSP90 was associated with malignancy in untreated patients. None of the patient sera showed antibodies to EGFR, while 2 and 1 patients showed reactivity to ErbB2 and PSA, respectively. We also demonstrated that 8 months after therapy the IgG serum levels to CI, CIII, FN and HSP90 significantly decreased. Conversely, the level of P0 autoantibodies increased after therapy in 10 patients. Five of the 10 patients with increased levels of P0 autoantibodies were treated with RT plus hormonotherapy. Treatment of patients did not change the levels of antibodies against EGFR, ErbB2 and PSA. Our results indicated that the modification of antibody level to self molecules after standard treatment of prostate cancer patients is influenced by the type of antigen. Ribosomal P0 protein appears to be a high immunogenic antigen and its immunogenicity increases following RT. In addition, 10 patients with increased levels of autoantibodies to P0 showed PSA mean levels lower than the remaining 25 patients at 18 months. This study may contribute to a better understanding of the immunobiological behavior of prostate cancer patients following standard treatment.

Prostasomes are mediators of intercellular communication: from basic research to clinical implications

Prostasomes are nanosized microvesicles secreted by acinar epithelial cells of the prostate gland. Furthermore, they are intracellular microvesicles inside another larger vesicle, a so-called storage vesicle, equivalent to multivesicular bodies of late endosomal origin. Prostasomes are thought to play an important role in intercellular communication by direct interaction primarily between the immobile acinar cells of the prostate gland and the mobile spermatozoa. Prostasomes transfer not only membrane components but also genetic material to spermatozoa. They are rich in various transferable bioactive molecules (e.g., receptors and enzymes) that promote the fertilizing ability of spermatozoa. In this review, the pleiotropic biological effects of prostasomes that are relevant for successful fertilization will be discussed. The ability to synthesize and export prostasomes to the extracellular space is observed not only in normal prostate epithelial cells but also in malignant prostate cells. Release of prostasomes by prostate cancer cells suggests a role in malignant cell growth and proliferation. These findings may provide new therapeutic and diagnostic strategies.

Autoantibody against hypoxia-inducible factor prolyl hydroxylase-3 is a potential serological marker for renal cell carcinoma

PURPOSE

To verify the efficacy of a serum autoantibody against hypoxia-inducible factor prolyl hydroxylase-3 (PHD3) as a serological marker for RCC.

METHODS

Serum samples and surgically resected tumor tissue specimens were obtained from 22 patients with primary RCC, 15 of whom underwent radical nephrectomy and 7 partial nephrectomy. Preoperative serum samples were obtained just before tumor resection. Postoperative serum samples were obtained from 17 patients at least 1 month after tumor removal. Serum samples were also obtained from 26 healthy volunteers. Titers of the anti-PHD3 antibody (Ab) were determined by enzyme-linked immunosorbent assay.

RESULTS

Serum anti-PHD3 Ab titers were significantly higher in patients with RCC than in healthy volunteers (0.610 ± 0.023 vs. 0.591 ± 0.031, P = 0.0001). Using a cutoff point of 0.599, sensitivity, specificity, and positivity for prediction of RCC were 86.4, 57.7, and 63.3%, respectively. In all 17 patients, titers of serum anti-PHD3 were decreased after the surgical resection compared with those before operation (0.622 ± 0.023 vs. 0.580 ± 0.024, P = 0.0003).

CONCLUSIONS

The present study suggests that the anti-PHD3 Ab may be a novel serological marker for RCC and the titer may reflect the tumor burden in each individual.

Molecular biomarkers in prostate cancer

BACKGROUND

After more than two decades of clinical use, serum prostate-specific antigen (PSA) has increased the early diagnosis of prostate cancer, detecting the disease even when small volumes are present. Although stage migration of prostate cancer has occurred, PSA has well-known limitations, despite attempts at refinement and modification, such as the use of PSA velocity, which have been used to improve it. New biomarkers for prostate cancer have been discovered, with promising early results.

OBJECTIVE/METHODS

This article reviews the ubiquitous current literature on biomarkers in prostate cancer. A search using MEDLINE and EMBASE databases was performed and those articles reporting biomarkers in prostate cancer with clinically significant findings in terms of detection were analyzed. Immunohistochemical markers were not considered for this review.

RESULTS/CONCLUSION

Despite many markers being promising, no single marker has satisfied the criteria as a perfect candidate. Limited clinical use of IL-6, TGF-β1 and PCA3 has commenced, and further widespread availability of these tests is expected in the coming years. The future lies in artificial neural networks and panels of markers instead of individual assays. Although PSA has some well-known limitations, it is at present the best marker available for prostate cancer when used in conjunction with nomograms or risk calculators.

Antiprostasome antibodies are not an appropriate prognostic marker for prostate cancer

OBJECTIVE

Antiprostasome antibodies (APAs) have been identified in serum of patients with prostate cancer and have been proposed as a new marker for metastatic disease. This study reassesses the role of APAs as a prognostic indicator for prostate cancer.

MATERIAL AND METHODS

Serum samples from healthy controls (n=7) and patients with prostate cancer (n=22) were assayed for APAs using an enzyme-linked immunosorbent assay.

RESULTS

APAs in varying amounts were present in healthy individuals as well as in men with prostate cancer. Higher levels were inversely and significantly associated with prostate-specific antigen (PSA). No significant relationships were noted between APA levels and other parameters such as age, time since diagnosis, metastatic status, Gleason histological score and hormonal treatment.

CONCLUSIONS

The presence of serum APA is unlikely to be a strong prognostic indictor for prostate cancer on an individual basis as false positives will occur. However, such immune reactions which may be associated with PSA in cancer patients are in any case of interest in both the biology of prostate cancer and male fertility. The source of prostasomal antigen may be of critical importance to the outcome of the assay. However, immune reactions to prostasomes may be of considerable interest and warrant continued investigation.

Profiling tumor-associated autoantibodies for the detection of colon cancer

PURPOSE

The purpose of the present study was to screen the autoantibody signature of colon cancers to develop serum markers for colon cancer detection.

EXPERIMENTAL DESIGN

A phage cDNA expression library of colon cancer was built. The library was sequentially screened by a pool of 10 colon cancer sera, goat antihuman IgG, and a pool of two healthy sera to identify phage-expressed antigens recognized by tumor-associated antibodies. The clones picked out by these screening were subjected to a training set with 24 colon cancer sera and 24 healthy sera. The antigen combination, which got the most satisfactory classification, was tested by an independent set of 24 colon cancer sera with equal number of sera from normal donors. The carcinoembryonic antigen (CEA) level of these sera was detected for the additional classification analysis with or without the antigen combination.

RESULTS

A cDNA expression library consisting of 2 x 10(6) primary clones was prepared. After three turns of screening, 24 antigens recognized by tumor-associated antibodies were picked out for serum marker identification. The training set showed that a six-marker combination got the most satisfactory classification in a logistic regression model; leave-one-out validation achieved 91.7% sensitivity and 91.7% specificity. In a testing set with this marker panel, we correctly predicted 85% of the samples. Although according to CEA level alone, we correctly predicted 75% of the samples with 42% of cancer patients misclassified. When CEA was combined with the six markers, the sensitivity and specificity increased to 91.7% and 95.8%, respectively. The six antigen sequences in the phage display system are relatively short peptides. Only two of them showed homology to known protein sequences.

CONCLUSIONS

Autoantibodies against phage-expressed antigens derived from colon cancer tissues could be used as serum markers for the detection of colon cancer.

Serum antibodies against prostasomal clusterin in prostate cancer patients

OBJECTIVE

Clusterin is a ubiquitous secretory sulphated glycoprotein present in prostasomes. It is an anti-apoptotic mediator in prostate cancer and is among the most frequently occurring prostasomal proteins immunogenic in prostate cancer patients. The aim of the present study was to investigate the occurrence of anti-clusterin antibodies in the serum of patients with prostate cancer and whether there is a relationship between anti-clusterin antibody titres and other clinico-pathological variables.

MATERIAL AND METHODS

Serum samples were collected from 391 consecutive patients with suspected prostate cancer (150 benign prostate and 241 prostate cancer). The patients' serum samples were used in an ELISA where microtitre wells were coated with purified clusterin from serum of a healthy volunteer. Flow cytometric studies of clusterin and prostasomes were performed.

RESULTS

Flow cytometric analyses revealed the presence of clusterin on the surface of seminal prostasomes. Anti-clusterin ELISA titres in sera of patients did not differ significantly from those of a control group. A significant "inverse" correlation existed between anti-clusterin ELISA titres and lymph node metastases (p = 0.047), but only 11 out of 161 patients had metastases. These titres correlated significantly with total prostate (p = 0.021) and transitional zone (p = 0.015) volumes of the patients.

CONCLUSIONS

The correlation between serum anti-clusterin antibody titres and other clinico-pathological variables was generally weak in prostate cancer patients, although clusterin has been assigned an important role in tumourigenesis and progression of prostate cancer. However, the anti-clusterin antibody titre appeared to be related to prostate volume, correlating to both transitional zone volume and total volume of the prostate.

Cholesterol regulates prostasome release from secretory lysosomes in PC-3 human prostate cancer cells

Prostasomes are vesicles secreted by epithelial cells of the prostate gland. However, little is known about the mechanism and the regulation of prostasome secretion. Since endocytic organelles may be involved in prostasome release, PC-3-derived prostasomes were investigated by Western blot analysis for the presence of marker proteins normally associated with these organelles. Prostasomes secreted by PC-3 cells contain clathrin, Tsg101, Hrs, Rab11, Rab5, LAMP-1, LAMP-2, LAMP-3/CD63, and annexin II. Moreover, electron microscopy of PC-3 cells revealed the presence of characteristic multivesicular body-like secretory lysosomes containing vesicles with the same size-distribution as released prostasomes. Ultrastructural immunogold labelling showed that LAMP-1, LAMP-2 and LAMP-3/CD63 were associated with these vesicles. In addition, we have investigated whether cholesterol plays a role in prostasome release by the human prostate cancer cell line PC-3. Interestingly, prostasome release was significantly increased when the cholesterol levels of PC-3 cells were reduced by the cholesterol-sequestering agent methyl-beta-cyclodextrin (MBCD), or by treatment with lovastatin and mevalonate. In conclusion, these studies indicate that cholesterol plays an important role in the release of prostasomes by the human prostate cancer PC-3 cells, and suggest that prostasomes may be released after fusion of secretory lysosomes with the plasma membrane.