The chromogranin-A (CgA) in prostate cancer

Biosensors for prostate cancer detection

Prostate cancer (PC) is one of the most common tumors and a leading cause of mortality among men, resulting in ~375 000 deaths annually worldwide. Various analytical methods have been designed for quantitative and rapid detection of PC biomarkers. Electrochemical (EC), optical, and magnetic biosensors have been developed to detect tumor biomarkers in clinical and point-of-care (POC) settings. Although POC biosensors have shown potential for detection of PC biomarkers, some limitations, such as the sample preparation, should be considered. To tackle such shortcomings, new technologies have been utilized for development of more practical biosensors. Here, biosensing platforms for the detection of PC biomarkers such as immunosensors, aptasensors, genosensors, paper-based devices, microfluidic systems, and multiplex high-throughput platforms, are discussed.

Multiplexed Prostate Cancer Companion Diagnostic Devices

Prostate cancer (PCa) remains one of the most prominent forms of cancer for men. Since the early 1990s, Prostate-Specific Antigen (PSA) has been a commonly recognized PCa-associated protein biomarker. However, PSA testing has been shown to lack in specificity and sensitivity when needed to diagnose, monitor and/or treat PCa patients successfully. One enhancement could include the simultaneous detection of multiple PCa-associated protein biomarkers alongside PSA, also known as multiplexing. If conventional methods such as the enzyme-linked immunosorbent assay (ELISA) are used, multiplexed detection of such protein biomarkers can result in an increase in the required sample volume, in the complexity of the analytical procedures, and in adding to the cost. Using companion diagnostic devices such as biosensors, which can be portable and cost-effective with multiplexing capacities, may address these limitations. This review explores recent research for multiplexed PCa protein biomarker detection using optical and electrochemical biosensor platforms. Some of the novel and potential serum-based PCa protein biomarkers will be discussed in this review. In addition, this review discusses the importance of converting research protocols into multiplex point-of-care testing (xPOCT) devices to be used in near-patient settings, providing a more personalized approach to PCa patients’ diagnostic, surveillance and treatment management.

The role of serum neuron-specific enolase in patients with prostate cancer: a systematic review of the recent literature

In this systematic review, we evaluated the value of serum concentrations of neuron-specific enolase (NSE) in patients with prostate cancer (PCa) in order to clarify the possible role of NSE in the diagnosis, management, treatment and monitoring of PCa. A comprehensive search of the recent literature was conducted to find relevant data on the role of NSE in PCa. Two hundred and eighty-two records were revealed, and 19 articles including 1,772 patients with PCa (either confirmed or suspected) were selected. After reviewing the articles, the major result was that elevated serum NSE appears to correlate with prognosis in advanced PCa, particularly in patients with progressive and metastatic castration-resistant PCa. Based on the existing literature, the role of serum NSE in PCa patients should be further evaluated.

Calcium role in human carcinogenesis: a comprehensive analysis and critical review of literature

The central role played by calcium ion in biological systems has generated an interest for its potential implication in human malignancies. Thus, lines of research, on possible association of calcium metabolism regulation with tumorigenesis, implying disruptions and/or alterations of known molecular pathways, have been extensively researched in the recent decades. This paper is a critical synthesis of these findings, based on a functional approach of the calcium signaling toolkit. It provides strong support that this ubiquitous divalent cation is involved in cancer initiation, promotion, and progression. Different pathways have been outlined, involving equally different molecular and cellular structures. However, if the association between calcium and cancer can be described as constant, it is not always linear. We have identified several influencing factors among which the most relevant are (i) the changes in local or tissular concentrations of free calcium and (ii) the histological and physiological types of tissue involved. Such versatility at the molecular level may probably account for the conflicting findings reported by the epidemiological literature on calcium dietary intake and the risk to develop certain cancers such as the prostatic or mammary neoplasms. However, it also fuels the hypothesis that behind each cancer, a specific calcium pathway can be evidenced. Identifying such molecular interactions is probably a promising approach for further understanding and treatment options for the disease.

Small cell carcinoma of the prostate presenting with Cushing Syndrome. A narrative review of an uncommon condition

Small cell carcinoma (SCC) of the prostate is an uncommon condition; there are very few cases in which presenting symptoms are consistent with Cushing Syndrome (CS). We report a new case in which CS triggers the suspicion of an SCC of the prostate and a review of the published cases of SCC of the prostate presenting with CS. The origin of these neoplasms is still unclear. It may be suspected when laboratory features appear in patients diagnosed with prostatic adenocarcinoma which becomes resistant to specific therapy. SCC usually occurs after the 6th decade. Patients suffering SCC of the prostate presenting with CS usually present symptoms such as hypertension, hyperglycemia, alkalosis or hypokalemia; cushingoid phenotype is less frequent. Cortisol and ACTH levels are often high. Prostatic-specific antigen levels are usually normal. CT scan is the preferred imaging test to localize the lesion, but its performance may be improved by adding other tests, such as FDG-PET scan. All patients have metastatic disease at the time of diagnosis. Lymph nodes, liver and bone are the most frequent metastases sites. Surgery and Ketokonazole are the preferred treatments for CS. The prognosis is very poor: 2- and 5-year survival rates are 27.5 and 14.3%, respectively. Key messages When a patient presents with ectopic Cushing Syndrome but lungs are normal, an atypical localization should be suspected. We should suspect a prostatic origin if Cushing Syndrome is accompanied by obstructive inferior urinary tract symptoms or in the setting of a prostatic adenocarcinoma with rapid clinical and radiological progression with relatively low PSA levels. Although no imaging test is preferred to localize these tumors, FDG-PET-TC can be very useful. Hormone marker scintigraphy (e.g. somatostatin) could be used too. As Cushing Syndrome is a paraneoplastic phenomenon, treatment of the underlying disease may help control hypercortisolism manifestations. These tumors are usually metastatic by the time of diagnosis. They have very poor prognosis.

Prostate cancer and neuroendocrine differentiation: more neuronal, less endocrine?

Neuroendocrine differentiation (NED) marks a structural and functional feature of certain cancers, including prostate cancer (PCa), whereby the malignant tissue contains a significant proportion of cells displaying neuronal, endocrine, or mixed features. NED cells produce, and can secrete, a cocktail of mediators commonly encountered in the nervous system, which may stimulate and coordinate cancer growth. In PCa, NED appears during advanced stages, subsequent to treatment, and accompanies treatment resistance and poor prognosis. However, the term “neuroendocrine” in this context is intrinsically vague. This article seeks to provide a framework on which a unified view of NED might emerge. First, we review the mutually beneficial interplay between PCa and neural structures, mainly supported by cell biology experiments and neurological conditions. Next, we address the correlations between PCa and neural functions, as described in the literature. Based upon the integration of clinical and basic observations, we suggest that it is legitimate to seek for true neural differentiation, or neuromimicry, in cancer progression, most notably in PCa cells exhibiting what is commonly described as NED.

Chromogranin A is a reliable serum diagnostic biomarker for pancreatic neuroendocrine tumors but not for insulinomas

BACKGROUND

Pancreatic neuroendocrine tumors (PNETs) are a group of rare tumors. Chromogranin A (CgA) was considered as the most practical and useful serum tumor marker in PNET patients. But peripheral blood levels of CgA are not routinely tested in Chinese patients with PNETs. This study was to assess the diagnostic value of CgA in Chinese patients with PNETs especially in patients with insulinomas.

METHODS

Eighty-nine patients with PNETs including 57 insulinomas and 32 non-insulinoma PNETs as well as 86 healthy participants were enrolled in this study between September 2003 and June 2013. Serum levels of CgA were measured by ELISA method. Expression of CgA protein was detected in 26 PNET tissues including 14 insulinomas by immunohistochemical staining.

RESULTS

Serum levels of CgA in 89 PNET patients were significantly higher than that in healthy controls (P = 7.2 × 10-9). Serum levels of CgA in 57 patients with insulinomas (median 64.8 ng/ml, range 25-164) were slightly higher than the levels in healthy controls (median 53.4 ng/ml, range 39-94) but much lower than the levels in 32 patients with non-insulinoma PNETs (median 193 ng/ml, range 27-9021), P = 0.001. The serum CgA levels were reduced in 16 of 17 patients with insulinomas after tumor resection. ROC curve showed that CgA values at 60 ng/ml distinguished patients with insulinomas from healthy controls but its sensitivity and specificity were 66.7% and 73.3%, respectively. In contrast, CgA values at 74 ng/ml distinguished patients with non-insulinoma PNETs from healthy controls, and the sensitivity and specificity were 65.6% and 91.9%, respectively. Except for two insulinomas with negative staining of CgA, 12 insulinoma tissues showed positive staining of CgA.

CONCLUSION

CgA is a reliable serum diagnostic biomarker for PNETs but not for insulinomas.

Hepatocellualar carcinoma serum markers

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world. In most cases, HCC is diagnosed at a late stage. Therefore, the prognosis of patients with HCC is generally poor. The recommended screening strategy for patients with cirrhosis includes the determination of serum α-fetoprotein (AFP) levels and an abdominal ultrasound every 6 months to detect HCC at an earlier stage. AFP, however, is a marker characterized by poor sensitivity and specificity, and abdominal ultrasound is highly dependent on the operator's experience. In addition to AFP, Lens culinaris agglutinin-reactive AFP (AFP-L3), des-γ-carboxy prothrombin (DCP), glypican-3 (GPC-3), osteopontin (OPN), and several other biomarkers (such as squamous cell carcinoma antigen-immunoglobulin M complexes [SCCA-IgM], alpha-1-fucosidase [AFU], chromogranin A [CgA], human hepatocyte growth factor, insulin-like growth factor) have been proposed as markers for the early detection of HCC. For these markers, we describe the mechanisms of production, and their diagnostic and prognosis roles. None of them is optimal; however, when used together, their sensitivity in detecting HCC is increased. Recent research has shown that some biomarkers have mitogenic and migratory activities in the angiogenesis of HCC and are a factor of tumor growth.

Prognostic significance of neuroendocrine differentiation in prostate adenocarcinoma

Much progress has been made toward an understanding of the development and progression of prostate cancer (PC) and the factors that drive the development of androgen independence. Neuroendocrine (NE) cells may provide an intriguing link between NE cell differentiation (NED) and tumor progression in PC. NED in PC generally confers a more aggressive clinical behavior and less favorable prognosis than conventional PC. In this article, we review the known functions of NE cells in PC and discuss the current knowledge on stimulation of cancer proliferation, invasion, apoptosis resistance, serum and immunohistochemical markers, and the prognostic significance of NED in human PC.

Increased plasma concentrations of tumour markers in the absence of neoplasia

Tumour markers are a very heterogeneous group of molecules that are generally found in very small concentrations in the plasma and serum of healthy individuals. In the process of neoplastic differentiation the cell can synthesize, release, or induce synthesis of other cells, thus increasing their concentration in plasma and serum. These substances may also increase their plasma concentration in patients without cancer due to processes that increase the release or reduce catabolism, and so give rise to false positives. An understanding of the main physiopathological processes that increase the concentrations of these substances could improve our interpretation of tumour markers and their clinical application. In this study we review the physiopathological processes that may increase the plasma concentrations of tumour markers. We performed a bibliography review in PubMed, searching for causes of false positives for the following tumour markers: α-Fetoprotein, CA 125, CA 15-3, CA 19-9, CA 72-4, carcinoembryonic antigen, CYFRA 21-1, squamous cell carcinoma, prostatic specific antigen, β(2)-microglobulin, choriogonadotropin (β chain), chromogranin A, neuron specific enolase, HER2-neu, progastrin releasing peptide, S-100, and thyroglobulin. The results favour the use of tests which can identify pathological processes that may increase tumour marker concentrations.

Markers of bile duct tumors

Biliary tract carcinomas are relatively rare, representing less than 1% of cancers. However, their incidence has increased in Japan and in industrialized countries like the USA. Biliary tract tumors have a poor prognosis and a high mortality rate because they are usually detected late in the course of the disease; therapeutic treatment options are often limited and of minimal utility. Recent studies have shown the importance of serum and molecular markers in the diagnosis and follow up of biliary tract tumors. This review aims to introduce the main features of the most important serum and molecular markers of biliary tree tumors. Some considerable tumor markers are cancer antigen 125, carbohydrate antigen 19-9, carcinoembryonic antigen, chromogranin A, mucin 1, mucin 5, alpha-fetoprotein, claudins and cytokeratins.

Incidence of high chromogranin A serum levels in patients with non metastatic prostate adenocarcinoma

Background

ChromograninA in prostate carcinoma (PC) indicate NE differentiation. This tumour is more aggressive and resistant to hormone therapy.

Patients and methods

We analyzed the incidence of pre-operative ChromograninA serum levels in non metastatic PC patients. Serum PSA and ChromograninA were analyzed before treatment. Clinicopathological parameters were evaluated in relation to serum ChromograninA. 486 patients were enrolled.

Results

We found 352 pT2 and 134 pT3. 21 patients were N+. 278 patients had Gleason score levels <7; 173 patients had levels = 7 (122 were 3+4 and 51 4+3); and 35 patients with levels >7. Median PSA pre-operative level was 7.61 ng/ml. PSA was significantly associated with pT stage (pT2 with PSA abnormal 23.6% vs pT3 48.5%, p < 0.0001) and with a Gleason score (PSA abnormal 60% in the Gleason score was >7 vs 29.5% in the Gleason score = 7 vs 27.3% in the Gleason score <7, p < 0.0001). In 114 patients pre-operative ChromograninA levels were elevated (23.5%). Serum ChromograninA levels had no significant association with PSA (p = 0.44) and pT stage (p = 0.89). abnormal ChromograninA levels increased from a Gleason score of <7 (25.5%) to >7 (31.4%) (p = 0.12). The serum ChromograninA levels in the two groups of patients were subdivided before and after 2005 on the basis of different used assays, showing no correlation with serum ChromograninA and other parameters.

Conclusions

This study showed that ChromograninA levels correlated to NE differentiation and possible aggressiveness of PC. Pre-operative circulating ChromograninA could complement PSA in selecting more aggressive PC cases, particularly in the presence of a higher Gleason score. Complementary information is provided by the absence of a correlation between serum ChromograninA and PSA levels.

Serum markers of hepatocellular carcinoma

BACKGROUND

The hepatocellular carcinoma is one of the most common malignant tumors and carries a poor survival rate. The management of patients at risk for developing HCC remains intricate.

METHODS

A literature search identified potential markers for hepatocellular carcinoma. These markers were analysed and justification was provided for these factors' inclusion to (or exclusion from) the markers of hepatocellular carcinoma (HCC). A search of the literature was made using cancer literature and the PubMed database for the following keywords: "markers and HCC," "Lens culinaris agglutinin reactive AFP (AFP-L3) and HCC," "Des-γ-carboxy prothrombin (DCP) and HCC," "Glypican-3 and HCC," "Chromogranin A and HCC," "Transforming growth factor β1(TGF) and HCC," "α-l-fucosidase (AFU) and HCC," "Golgi protein-73 (GP73) and HCC," "Hepatocyte growth factor (HGF) and HCC," "Nervous growth factor (NGF) and HCC."

CONCLUSIONS

Despite the large number of studies devoted to the immunohistochemistry of HCC, at the present time, the absolute positive and negative markers for HCC are still lacking, and even those characterized by very high sensitivity and specificity do not have an universal diagnostic usefulness. Given the poor response to current therapies, a better understanding of the molecular pathways active in this disease could potentially provide new targets for therapy. However, AFP shows a low sensitivity, therefore other biomarkers have been developed to make an early diagnosis and improve patients' prognosis.

Clinical significance of polymorphism and expression of chromogranin a and endothelin-1 in prostate cancer

PURPOSE

We investigated the clinical significance of chromogranin A and endothelin-1 polymorphism and expression in prostate cancer.

MATERIALS AND METHODS

We analyzed 2 CHGA polymorphisms by polymerase chain reaction-restriction fragment length polymorphism in DNA samples of 435 patients with prostate cancer and 316 age matched male controls. Chromogranin A and endothelin-1 expression was evaluated by immunohistochemistry in prostate specimens of 114 men with prostate cancer who underwent radical retropubic prostatectomy and in 27 with bladder cancer who underwent radical cystectomy and served as controls.

RESULTS

For the CHGA Glu264Asp polymorphism men with the GG genotype were at 2.05 times higher risk for prostate cancer than men with the CC genotype (p = 0.014). In men with prostate cancer higher chromogranin A immunohistochemistry grade was associated with higher stage and higher Gleason score (p = 0.011 and 0.044, respectively). Multivariate analysis showed that chromogranin A immunohistochemistry grade was an independent variable for predicting biochemical failure after radical prostatectomy (p = 0.023). Higher endothelin-1 expression was observed in prostate cancers (p = 0.011), especially those with a higher Gleason score (p = 0.042). There was no significant relationship between chromogranin A polymorphisms, and chromogranin A and endothelin-1 expression.

CONCLUSIONS

Polymorphism and expression of chromogranin A and endothelin-1 have clinical significance in prostate cancer. Chromogranin A expression was an independent predictor of biochemical failure after prostatectomy in patients with localized prostate cancer.

Chromogranin A (CgA) serum level as a marker of progression in hepatocellular carcinoma (HCC) of elderly patients

The observation of neuroendocrine (NE) activity during clinical course of hepatocellular carcinoma (HCC), suggested the use of NE serum markers to detect it. Thus we have evaluated the usefulness of serum measurements of CgA in monitoring disease activity of HCC. We investigated the role of serum concentrations of CgA, alpha-fetoprotein (AFP) and des-gamma-carboxyl-prothrombin (DCP) in 55 patients with HCC, 27 patients with cirrhosis, 22 patients with chronic hepatitis and a control group of 20 volunteers and the relationship between the pre-treatment serum CgA and clinical stages of the disease. CgA was significantly higher in the patients affected by HCC as compared with those affected by either hepatitis or cirrhosis (p<0.001). We also observed significant differences, comparing CgA serum levels in the tumor classes T1-T4: T1 vs. T2 (p<0.001), T1 vs. T3 (p<0.001), T1 vs. T4 (p<0.001), T2 vs. T3 (p<0.001), T2 vs. T4 (p<0.001) and T3 vs. T4 (p<0.001). CgA levels were significantly higher in poorly differentiated HCC vs. well differentiated (p<0.05) and medium differentiated ones (p<0.001). Also the comparison between Child-Pugh degree A and C showed a significant difference in CgA levels (p<0.001). Thereby, patients with higher CgA level had poor survival and showed poor prognosis, compared to those with lower CgA level, i.e., the CgA is useful in monitoring progression of disease and may assist as a prognostic indicator.

Terminal and progenitor lineage-survival oncogenes as cancer markers

Tumour classification has traditionally focused on differentiation and cellular morphology, and latterly on the application of genomic approaches. By combining chromatin immunoprecipitation with expression array, it has been possible to identify direct gene targets for transcription factors for nuclear hormone receptors. At the same time, there have been great strides in deriving stem and progenitor cells from tissues. It is therefore timely to propose that pairing the isolation of these cell subpopulations from tissues and tumours with these genomics approaches will reveal conserved gene targets for transcription factors. By focusing on transcription factors (lineage-survival oncogenes) with roles in both organogenesis and tumourigenesis at multiple organ sites, we suggest that this comparative genomics approach will enable developmental biology to be used more fully in relation to understanding tumour progression and will reveal new cancer markers. We focus here on neurogenesis and neuroendocrine differentiation in tumours.

Neuroendocrine differentiation in stage D2 prostate cancers

OBJECTIVES

Chromogranin A (CgA) and neuro-specific enolase (NSE) are gaining acceptance as markers of several types of neuroendocrine tumors and the concentration of CgA and NSE have been reported to be elevated in relation to neuroendocrine differentiation of prostate cancer. The aim of the present study was to examine the correlation between the immunohistochemical (IHC) findings and serum value for CgA and NSE in untreated stage D(2) prostate cancer patients.

METHODS

Immunohistochemistry was carried out using antibodies against CgA and NSE in 58 patients and, pretreatment serum CgA and NSE levels were measured by monoclonal immunoradiometric assay in 18 patients with stage D(2) prostate cancer treated by androgen ablation. We examined the relationship of the pretreatment serum level to IHC findings for CgA and NSE in prostate cancer patients to clinicopathological parameters, and prognosis. Also, we evaluated the correlation of IHC findings to serum levels for CgA and NSE.

RESULTS

There was a statistically significant correlation between CgA positivity and serum CgA level (P = 0.0421). However, there was no statistically significant correlation between NSE positivity and serum NSE level (P > 0.05). We divided stage D(2) patients into three groups according to IHC positivity of CgA and NSE. The cause-specific survival was significantly poorer in patients with strongly positive (++) patients for independent CgA and combined CgA with NSE (P = 0.0379). Multivariate analysis of cause-specific survivals in patients with stage D(2) prostate cancer demonstrated that strong IHC stain was considered as independent variable associated with greater risk of death (P = 0.0142).

CONCLUSION

Neuroendocrine differentiation in stage D(2) prostate cancer has attracted considerable attention as a potentially findings prognosis. Thus, CgA had a stronger relationship between serum levels and IHC positivity in contrast to NSE, suggesting clinical usefulness as a tumor marker in predicting the extent of neuroendocrine differentiation in prostate cancer.

Loss of mitochondrial membrane potential is inhibited by bombesin in etoposide-induced apoptosis in PC-3 prostate carcinoma cells

Neuroendocrine secretory products and their interactions with epithelial prostate cells are currently under investigation in order to understand their significance in the pathogenesis, prognosis, and therapy of prostate carcinoma. These neuropeptides have the potential to disrupt the balance between cell death and cell growth in the tumor. Our research was based on the role of bombesin in modulating the mitochondrial membrane potential (Delta psi(m)) in cell death induced by etoposide on PC-3 cells. Cells were cultured and stained with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1). At low membrane potentials, JC-1 produces a green fluorescence, and at high membrane potentials, it forms "J aggregates" with red fluorescence. Cells were examined in a confocal microscope. For quantitative analyses, regions of interest were selected. The size, number of pixels, and ratios between fluorescence intensity in the red and green channels in each region of interest were calculated. The loss of Delta psi(m) in etoposide-treated PC-3 cells was prevented by bombesin. The quantitative analysis of JC-1-stained cells revealed a significant decrease in the red (high Delta psi(m)) to green (low Delta psi(m)) ratio in etoposide-treated cells when compared with control cells, which was restored in the presence of bombesin (P < 0.00001). The interaction between treatments and area (P = 0.0002) was highly significant, and confirms that PC-3 cells keep their apoptosis machinery, showing an apoptotic volume decrease in response to etoposide. The protection by bombesin occurs by inhibition of apoptosis and maintenance of mitochondrial integrity. New therapeutic protocols and trials need to be developed to test drugs acting through the neutralization of antiapoptotic intracellular pathways mediated by neuroendocrine hormones.

Investigation of the molecular profile of basal cell carcinoma using whole genome microarrays

Background

Skin cancer accounts for 1/3 of all newly diagnosed cancer. Although seldom fatal, basal cell carcinoma (BCC) is associated with severe disfigurement and morbidity. BCC has a unique interest for researchers, as although it is often locally invasive, it rarely metastasises. This paper, reporting the first whole genome expression microarray analysis of skin cancer, aimed to investigate the molecular profile of BCC in comparison to non-cancerous skin biopsies. RNA from BCC and normal skin specimens was analysed using Affymetrix whole genome microarrays. A Welch t-test was applied to data normalised using dCHIP to identify significant differentially-expressed genes between BCC and normal specimens. Principal component analysis and support vector machine analysis were performed on resulting genelists, Genmapp was used to identify pathways affected, and GOstat aided identification of areas of gene ontology more highly represented on these lists than would be expected by chance.

Results

Following normalisation, specimens clustered into groups of BCC specimens and of normal skin specimens. Of the 54,675 gene transcripts/variants analysed, 3,921 were differentially expressed between BCC and normal skin specimens. Of these, 2,108 were significantly up-regulated and 1,813 were statistically significantly down-regulated in BCCs.

Conclusion

Functional gene sets differentially expressed include those involved in transcription, proliferation, cell motility, apoptosis and metabolism. As expected, members of the Wnt and hedgehog pathways were found to be significantly different between BCC and normal specimens, as were many previously undescribed changes in gene expression between normal and BCC specimens, including basonuclin2 and mrp9. Quantitative-PCR analysis confirmed our microarray results, identifying novel potential biomarkers for BCC.

Molecular markers of prostate cancer

Although prostate-specific antigen (PSA) has evolved as a very useful tool for detection of prostate cancer, there remains an urgent need for more accurate biomarkers to diagnose prostate cancer and predict cancer-related outcomes. Recent advances in the study of proteomics and high throughput techniques have led to the discovery of many potential biomarkers for prostate cancer. This article briefly reviews the current status of PSA testing and discusses several candidate protein biomarkers for prostate cancer, as well as highlighting some recent proteomic discoveries with the potential to supplement or even replace PSA for the diagnosis and prognosis of prostate cancer.