Importance of serum amyloid A (SAA) level in monitoring disease activity and response to therapy in patients with prostate cancer

Inflammation and Tumor Progression: The Differential Impact of SAA in Breast Cancer Models

Background: Previous research has shown that the Serum Amyloid A (SAA) protein family is intricately involved in inflammatory signaling and various disease pathologies. We have previously demonstrated that SAA is associated with increased colitis disease severity and the promotion of tumorigenesis. However, the specific role of SAA proteins in breast cancer pathology remains unclear. Therefore, we investigated the role of systemic SAA1 and SAA2 (SAA1/2) in a triple-negative breast cancer mouse model. Methods: Syngeneic breast tumors were established in wild-type mice, and mice lacking the SAA1/2 (SAADKO). Subsequently, tumor volume was monitored, species survival determined, the inflammatory profiles of mice assessed with a multiplex assay, and tumor molecular biology and histology characterized with Western blotting and H&E histological staining. Results: WT tumor-bearing mice had increased levels of plasma SAA compared to wild-type control mice, while SAADKO control and tumor-bearing mice presented with lower levels of SAA in their plasma. SAADKO tumor-bearing mice also displayed significantly lower concentrations of systemic inflammatory markers. Tumors from SAADKO mice overall had lower levels of SAA compared to tumors from wild-type mice, decreased apoptosis and inflammasome signaling, and little to no tumor necrosis. Conclusions: We demonstrated that systemic SAA1/2 stimulates the activation of the NLRP3 inflammasome in breast tumors, leading to the production of pro-inflammatory cytokines. This, in turn, promoted apoptosis and tumor necrosis but did not significantly impact tumor growth or histological grading.

Paraneoplastic Glomerular Diseases

Paraneoplastic glomerular disease (PGD) develops from tumor cell products, leading to renal dysfunction. Unlike direct tumor effects, PGD illustrates the complex association between cancer and diverse clinical presentations and outcomes. Initially detected in a Hodgkin's disease patient, current research has defined diagnostic criteria based on PGD symptoms and cancer progression. PGDs, although rare (found in <1% of adult cancer patients with overt renal manifestations), are crucial, as they can signal cancer onset and frequently resist standard glomerulonephritis treatments. The emerging field of onconephrology studies this relationship between kidney disorders and cancers. The exact cause of many PGD cases remains unknown. This review examines PGDs, their clinicopathological features, related cancers, and mechanisms, emphasizing the need for early diagnosis and tailored treatment for kidney disease and linked cancer.

The Etiology and Pathophysiology Genesis of Benign Prostatic Hyperplasia and Prostate Cancer: A New Perspective

Background: The etiology of benign prostatic hyperplasia and prostate cancer are unknown, with ageing being the greatness risk factor. Methods: This new perspective evaluates the available interdisciplinary evidence regarding prostate ageing in terms of the cell biology of regulation and homeostasis, which could explain the timeline of evolutionary cancer biology as degenerative, inflammatory and neoplasm progressions in these multifactorial and heterogeneous prostatic diseases. Results: This prostate ageing degeneration hypothesis encompasses the testosterone-vascular-inflamm-ageing triad, along with the cell biology regulation of amyloidosis and autophagy within an evolutionary tumorigenesis microenvironment. Conclusions: An understanding of these biological processes of prostate ageing can provide potential strategies for early prevention and could contribute to maintaining quality of life for the ageing individual along with substantial medical cost savings.

Identification of serum proteins and multivariate models for diagnosis and therapeutic monitoring of lung cancer

Lung cancer is one of the most prevalent cancers and has very poor treatment outcome. Biomarkers useful for screening and assessing early therapeutic response may significantly improve the therapeutic outcome but are still lacking. In this study, serum samples from 218 non-small cell lung cancer (NSCLC) patients, 34 small cell lung cancer (SCLC) patients and 171 matched healthy controls from China were analyzed for 11 proteins using the Luminex multiplex assay. Eight of the 11 proteins (OPN, SAA, CRP, CYFRA21.1, CEA, NSE, AGP and HGF) are significantly elevated in NSCLC and SCLC (p = 10⁻⁵−10⁻⁵⁹). At the individual protein level, OPN has the best diagnostic value for NSCLC (AUC = 0.92), two acute phase proteins (SAA and CRP) have AUC near 0.83, while CEA and CYFRA21.1 also possess good AUC (0.81 and 0.77, respectively). More importantly, several three-protein combinations that contain OPN and CEA plus one of four proteins (CRP, SAA, CYFRA21.1 or NSE) have excellent diagnostic potential for NSCLC (AUC = 0.96). Four proteins (CYFRA21.1, CRP, SAA and NSE) are severely reduced and three proteins (OPN, MIF and NSE) are moderately decreased after platinum-based chemotherapy. Therapeutic response index (TRI) computed with 3–5 proteins suggests that approximately 25% of the NSCLC patients respond well to the therapy and TRI is significantly correlated with pre-treatment protein levels. Our data suggest that therapeutic response in NSCLC patients can be effectively measured but personalized biomarkers may be needed to monitor different subsets of patients.

Significance of amyloid A immunoexpression in the prognosis of renal cell carcinoma

The study investigated immunoexpression of amyloid A (AA) in clear cell renal cell carcinoma (CCRCC) and evaluated its clinicopathologic correlation, particularly in disease progression. Expression of AA protein was evaluated in patients with CCRCC by immunohistochemistry. 146 cancerous tissue samples from 86 male and 60 female patients were studied. The relationship between AA protein expression and TNM stage, nuclear grade, renal capsule invasion, perirenal invasion, and survival of the patients were assessed. Thirty four percent of CCRCC cases were AA positive. The positive AA immunoexpression was related to higher Fuhrman nuclear grade, presence of perirenal invasion of the tumor, and poor survival of patients with CCRCC. There was not any statistically significant difference between patients' gender, status of capsule invasion, and stages of the tumor in terms of AA immunoexpression. Tumor stage (Hazard ratio (HR) = 7.76 (95% CI: 2.43-24.8) for stage 3 and HR = 29.9 (95% CI: 6.97-128.32) for stage 4) and AA immunoexpression (HR = 2.16 (95% CI: 1.01-4.64) were found to be associated with survival of the patients with CCRCC in Cox regression analysis. Immunoexpression of AA was increased in high grade CCRCCs. Immunoexpression of AA was associated with poor survival in patients with CCRCC. Thus, AA staining might be used as a useful immunohistological marker for the prediction of poor prognosis in renal cell cancer.

Inflammatory serum proteins are severely altered in metastatic gastric adenocarcinoma patients from the Chinese population

BACKGROUND

Inflammation is one of the major hallmarks of cancer. This study was designed to profile a panel of inflammatory mediators in gastric adenocarcinoma (GA) and to identify their potential differences separately in metastatic and non-metastatic patient subgroups.

METHODS

Serum samples from 216 GA patients and 333 healthy controls from China were analyzed for six proteins using the Luminex multiplex assay.

RESULTS

The serum levels for all the six proteins were significantly elevated in metastatic GA compared to non-metastatic GA. Two acute phase proteins (SAA and CRP) and a CXC chemokine (GRO) were significantly elevated in metastatic GA (p <0.01) but smaller changes were observed in non-metastatic GA compared to healthy controls. OPN is moderately increased in non-metastatic GA (2.05-fold) and more severely elevated in metastatic GA (3.34-fold). Surprisingly, soluble VCAM1 and AGP were significantly lower in both non-metastatic and metastatic GA patients compared to controls. Several individual proteins were shown to possess moderate diagnostic value for non-metastatic GA (AUC = 0.786, 0.833, 0.823 for OPN, sVCAM1 and AGP, respectively) and metastatic GA (AUC = 0.931, 0.720, 0.834 and 0.737 for OPN, sVCAM1, SAA and CRP, respectively). However, protein combinations further improve the diagnostic potential for both non-metastatic GA (best AUC = 0.946) and metastatic GA (best AUC = 0.963). The protein combination with best AUC value for both comparisons is OPN+sVCAM1+AGP+SAA.

CONCLUSIONS

These results suggest that several serum proteins are directly related to the severity of gastric cancer. Overall, stronger associations are observed with metastatic than non-metastatic GA as the protein changes are greater with the metastatic status. A combination of these serum proteins may serve as non-invasive markers to assess the severity status and stage of gastric cancer.

Elevated levels of circulating IL-7 and IL-15 in patients with early stage prostate cancer

Background

Chronic inflammation has been suggested to favour prostate cancer (PCA) development. Interleukins (IL) represent essential inflammation mediators. IL-2, IL-7, IL-15 and IL-21, sharing a common receptor γ chain (c-γ), control T lymphocyte homeostasis and proliferation and play major roles in regulating cancer-immune system interactions. We evaluated local IL-2, IL-7, IL-15 and IL-21 gene expression in prostate tissues from patients with early stage PCA or benign prostatic hyperplasia (BPH). As control, we used IL-6 gene, encoding an IL involved in PCA progression. IL-6, IL-7 and IL-15 titres were also measured in patients' sera.

Methods

Eighty patients with BPH and 79 with early (1 to 2c) stage PCA were enrolled. Gene expression in prostate tissues was analyzed by quantitative real-time PCR (qRT-PCR). Serum IL concentrations and acute phase protein titres were evaluated by ELISA. Mann-Whitney, Wilcoxon and χ² tests were used to compare IL gene expression and serum titers in the two groups of patients. Receiver operating characteristic (ROC) curves were constructed to evaluate the possibility to distinguish sera from different groups of patients based on IL titers.

Results

IL-2 and IL-21 gene expression was comparably detectable, with low frequency and at low extents, in PCA and BPH tissues. In contrast, IL-6, IL-7 and IL-15 genes were expressed more frequently (p < 0.0001, p = 0.0047 and p = 0.0085, respectively) and to significantly higher extents (p = 0.0051, p = 0.0310 and p = 0.0205, respectively) in early stage PCA than in BPH tissues. Corresponding proteins could be detected to significantly higher amounts in sera from patients with localized PCA, than in those from patients with BPH (p = 0.0153, p = 0.0174 and p = 0.0064, respectively). Analysis of ROC curves indicates that IL-7 (p = 0.0039), but not IL-6 (p = 0.2938) or IL-15 (p = 0.1804) titres were able to distinguish sera from patients with malignancy from those from patients with benign disease. Serum titres of C reactive (CRP), high mobility group B1 (HMGB1) and serum amyloid A (SAA) acute phase proteins were similar in both groups of patients.

Conclusions

Expression IL-7 and IL-15 genes in prostate tissues and corresponding serum titres are significantly increased in patients with early stage PCA as compared with patients with BPH.

Serum biomarkers which correlate with failure to respond to immunotherapy and tumor progression in a murine colorectal cancer model

PURPOSE

To advance our understanding of mechanisms involved in tumor progression/regression, a CT26 colorectal mouse model treated intra-tumorally with DISC-herpes simplex virus as immunotherapy was used in the discovery and validation phases to investigate and ultimately identify biomarkers correlating with the failure to respond to immunotherapy.

EXPERIMENTAL DESIGN

For the discovery phase, serum protein/peptide profiles of a retrospective sample collection (total n=70) were analyzed using MALDI-TOF-MS combined with artificial neural networks. Following identification of the key predictive peptides using ESI-MS/MS, validation of the identified proteins was carried out on serum and tissues collected in an independent sample set (total n=60).

RESULTS

Artificial neural network analysis resulted in four discriminatory peaks with an accuracy of 86%, sensitivity of 90% and specificity of 81% between the progressor/regressor groups. Three of the identified discriminatory markers were upregulated and demonstrated a positive correlation with tumor progression following DISC-herpes simplex virus therapy. Immunovalidation studies corroborated the MALDI-TOF-MS findings. Immunohistochemistry revealed that serum amyloid A-1 and serum amyloid P produced in the liver localized intracellularly in CT26 tumor tissue.

CONCLUSIONS

MALDI-TOF-MS and BI analysis of the serum proteome of tumor-bearer mice undergoing immunotherapy, identified biomarkers associating with "failure to respond" and biological arrays confirmed these findings.

Identification and validation of SAA as a potential lung cancer biomarker and its involvement in metastatic pathogenesis of lung cancer

Lung cancer is recently regarded as an overhealed inflammatory disease. Serum amyloid A (SAA) is known as an acute phase protein, but it is likely involved in the cancer pathogenesis. We identified both SAA1 and SAA2 in the pooled sera of lung cancer patients but not in the healthy control, by LC-MS/MS analysis. We found that about 14-fold higher levels of SAA in lung cancer patients' sera and plasma compared to healthy controls by ELISA using total 350 samples (13.89 ± 37.18 vs 190.49 ± 234.70 ug/mL). The SAA levels were also significantly higher than in other pulmonary disease or other cancers. An immunohistochemical study using tissue microarray showed that, unlike other cancer tissues, lung cancer tissues highly express SAA. Further in vitro experiments showed that SAA is induced from lung cancer cells by the interaction with THP-1 monocytes and this, in return, induces MMP-9 from THP-1. In in vivo animal models, overexpressed SAA promoted Lewis lung carcinoma (LLC) cells to metastasize and colonize in the lung. Our data suggest that a higher concentration of SAA can serve as an indicator of lung adenocarcinoma and represents a therapeutic target for the inhibition of lung cancer metastasis.

Selenium-responsive proteins in the sera of selenium-enriched yeast-supplemented healthy African American and Caucasian men

BACKGROUND

Studies have shown that supplementation of adult men with selenium-enriched yeast (SY) was protective against prostate cancer (PCa) and also reduced oxidative stress and levels of prostate-specific antigen. Here, we determined the effect of SY supplementation on global serum protein expression in healthy men to provide new insights into the mechanism of selenium chemoprevention; such proteins may also serve as biomarkers of disease progression.

METHODS

Serum samples from 36 adult men were obtained from our previous SY clinical trial, 9 months after supplementation with either SY (247 microg/d; n = 17) or placebo (nonenriched yeast; n = 19).

RESULTS

Proteomic profiling using two-dimensional difference in gel electrophoresis followed by liquid chromatography-tandem mass spectrometry revealed a total of 1,496 candidate proteins, of which, 11 were differentially expressed in the SY group as compared with placebo. Eight proteins were upregulated [clusterin isoform 1 (CLU), transthyretin, alpha-1B-glycoprotein, transferrin, complement component 4B proprotein, isocitrate dehydrogenase, haptoglobin, and keratin 1] and three proteins were downregulated [alpha-1 antitrypsin (AAT), angiotensin precursor, and albumin precursor] by SY. All of the identified proteins were redox-sensitive or involved in the regulation of redox status. Because both AAT and CLU have been previously linked to PCa development, their identities were confirmed by two-dimensional Western blot analysis.

CONCLUSIONS

We identified AAT and CLU as potential candidate proteins involved in the mechanism of PCa prevention by SY. Collectively, proteins identified in this study might serve as potential new biomarkers for monitoring and comparing responses to selenium-based chemopreventive agents.

IMPACT

Proteomic analysis of serum might be useful for the early detection and monitoring efficacy of chemopreventive agents.

Liver proteins as sensor of human malignancies and inflammation

In this review we would like to highlight the importance of acute-phase proteins as sensor of diseases. Both acute-phase protein levels and glycosylation have been reported to be altered in inflammation and other diseases including cancer. Factors that promote acute-phase protein synthesis and enhance the expression of specific glycosyltransferases, such as sialyltransferases and fucosyltransferases, may be up-regulated in some tumours and would explain the changes in acute-phase protein levels and the specific N-glycosylation modifications of some acute-phase proteins in cancer. However, further studies are required to define the potential clinical application of these acute-phase protein cancer-specific modifications as possible cancer diagnostic or monitoring tools.

Plasma levels of C-reactive protein and serum amyloid A and gastric cancer in a nested case-control study: Japan Public Health Center-based prospective study

Gastric carcinogenesis may be under the combined influence of factors related to the host, Helicobacter pylori bacterial virulence and the environment. One possible host-related factor is the inflammatory or immune response. To clarify this point, we investigated the association between plasma levels of C-reactive protein (CRP) and serum amyloid A (SAA) and the subsequent risk of gastric cancer in a population-based nested case-control study. Subjects were observed from 1990 to 2004. Among 36 745 subjects who answered the baseline questionnaire and provided blood samples, 494 gastric cancer cases were identified and matched to 494 controls for our analysis. The overall distribution of CRP and SAA was not apparently associated with the development of gastric cancer. However, a statistically significant increased risk was observed when subjects were categorized dichotomously. The adjusted odds ratio (OR) for the development of gastric cancer for the CRP-positive group (CRP > 0.18 mg/dl) compared with the CRP-negative group was 1.90 [95% confidence interval (CI): 1.19-3.02, P = 0.007]. The OR for the SAA-positive group (SAA > 8 mug/ml) compared with the SAA-negative group was 1.93 (95% CI: 1.22-3.07, P = 0.005). In conclusion, our results suggest that those who react strongly to inflammation or who have a high host immune response, as reflected by extremely elevated plasma levels of CRP and SAA, are at a high risk to develop gastric cancer.

Cancer-specific MALDI-TOF profiles of blood serum and plasma: biological meaning and perspectives

MALDI-TOF mass-spectrometry has become a popular tool of cancer research during the last decade. High throughput and relative simplicity of this technology have made it attractive for biomarker discovery and validation across various platforms in blood serum/plasma. Many technical approaches have been developed for plasma/serum profiling including protein-chip based SELDI-TOF mass-spectrometry, purification of serum on magnetic beads, analysis of carrier-associated fraction and mass-spectrometric immunoassays. Extensive data about the identity of differential features detected on mass-spectra up to now makes it possible to draw conclusions about potency and perspectives of MALDI-TOF mass-spectrometry in this field. A great majority of identified differentially expressed proteins are either house-keeping or inflammatory proteins as well as their modifications or fragments. Discriminating ability of mass-spectra is likely to be based on differential modification and fragmentation patterns of abundant serum proteins reflecting activity of enzymes including proteases and their inhibitors.

Aberrant expression of serum amyloid A in head and neck squamous cell carcinoma

Serum amyloid A (SAA) is an acute-phase reactant, the blood level of which is often elevated in response to some types of neoplasia. Here, we investigated expression of the gene SAA1 and the protein SAA in head and neck squamous cell carcinoma (HNSCC) and normal oral mucosal tissues as well as blood SAA levels in HNSCC patients. Also, we investigated the effects of inhibiting signal transducer and activator of transcription 3 (STAT3) signaling on SAA1 expression in the HNSCC cell line SAS. Serum SAA levels in HNSCC patients were significantly higher than those in healthy volunteers. In addition, real-time quantitative reverse transcription-polymerase chain reaction analysis revealed a significantly higher SAA1 expression level in HNSCC than in normal mucosa (P < 0.0001). Furthermore, Western blot and immunohistochemical analyzes revealed that high expression of SAA in carcinomas was detected predominantly in tumor cells, but not in normal mucosal tissues. An inhibitor of STAT3 activation, AG490, significantly reduced SAA1 expression in SAS cells. These data demonstrated that SAA was up-regulated in HNSCC through the Janus kinase-STAT3 pathway.

Serum amyloid A: an acute-phase protein involved in tumour pathogenesis

The synthesis of acute-phase protein serum amyloid A (SAA) is largely regulated by inflammation- associated cytokines and a high concentration of circulating SAA may represent an ideal marker for acute and chronic inflammatory diseases. However, SAA is also synthesized in extrahepatic tissues, e.g. human carcinoma metastases and cancer cell lines. An increasing body of in vitro data supports the concept of involvement of SAA in carcinogenesis and neoplastic diseases. Accumulating evidence suggests that SAA might be included in a group of biomarkers to detect a pattern of physiological events that reflect the growth of malignancy and host response. This review is meant to provide a broad overview of the many ways that SAA could contribute to tumour development, and accelerate tumour progression and metastasis, and to gain a better understanding of this acute-phase reactant as a possible link between chronic inflammation and neoplasia.

Expression of serum amyloid A transcripts in human bone tissues, differentiated osteoblast-like stem cells and human osteosarcoma cell lines

Although the liver is the primary site of cytokine-mediated expression of acute-phase serum amyloid A (SAA) protein, extrahepatic production has also been reported. Besides its role in amyloidosis and lipid homeostasis during the acute-phase, SAA has recently been assumed to contribute to bone and cartilage destruction. However, expression of SAA in human osteogenic tissue has not been studied. Therefore, we first show that SAA1 (coding for the major SAA isoform) but not SAA2 transcripts are expressed in human trabecular and cortical bone fractions and bone marrow. Next, we show expression of (i) IL-1, IL-6, and TNF receptor transcripts; (ii) the human homolog of SAA-activating factor-1 (SAF-1, a transcription factor involved in cytokine-mediated induction of SAA genes); and (iii) SAA1/2 transcripts in non-differentiated and, to a higher extent, in osteoblast-like differentiated human mesenchymal stem cells. Third, we provide evidence that human osteoblast-like cells of tumor origin (MG-63 and SAOS-2) express SAF-1 under basal conditions. SAA1/2 transcripts are expressed under basal conditions (SAOS-2) and cytokine-mediated conditions (MG-63 and SAOS-2). RT-PCR, Western blot analysis, and immunofluorescence technique confirmed cytokine-mediated expression of SAA on RNA and protein level in osteosarcoma cell lines while SAA4, a protein of unknown function, is constitutively expressed in all osteogenic tissues investigated.

Serum protein profiling to identify high-risk neuroblastoma: preclinical relevance of blood-based biomarkers

INTRODUCTION

Development of early detection assays for advanced stage neuroblastoma (NB) remains elusive. We have previously shown that serum protein profiling technologies can differentiate healthy from NB children. As various sources of patient related bias exist in serum proteins, we hypothesized a well controlled animal model may provide a better method to identify tumor blood-based markers during NB progression.

METHODS

Tumors were induced in the left kidneys of nude mice by the injection of cultured human NB cells (10(6)). Sera were collected from control and tumor-bearing mice at 2, 4, and 6 wk. Albumin-depleted sera were subjected to comparative proteomic profiling using 2D gel electrophoresis. Paired samples at each time point were analyzed and differentially expressed serum proteins were identified by mass spectrometry. Additionally, sera proteomic analysis from children with Stage IV NB and healthy controls were performed.

RESULTS

Overexpression of five mouse serum proteins [alpha(1)-acid glycoprotein, alpha(1)-antitrypsin, alpha(2)-macroglobulin, serum amyloid P-component, and serum amyloid A) were found only in NB-bearing mice. Changes in protein abundance were found to increase 2.5-fold (P < or = 0.05) between 2-, 4-, and 6-wk old mice. Underexpression of immunoglobulin kappa chain constant region was observed in the sera of tumor bearing mice compared with controls (2.5-fold, P < or = 0.05). Among NB patients, alpha(1)-acid glycoprotein, apolipoprotein A-IV, haptoglobin, and serum amyloid A were found to be up-regulated.

CONCLUSIONS

We identified distinct acute phase proteins that show up-regulation in both an animal tumor model and high-risk NB patients. As these serum proteins have been recognized as markers of tumor progression and prognosis in human malignancies, the validation of these polypeptides may enable serum proteomic profiling to become a valuable tool for identifying high-risk NB.

Evaluation of serum amyloid A as a biomarker for gastric cancer

BACKGROUND

Serum amyloid A (SAA) is a useful biomarker for gastric cancer in an animal model. We investigated the potential of SAA as a biomarker for gastric cancer in humans.

METHODS

Serum levels of SAA from 96 gastric cancer patients were measured before and after curative gastrectomy; 32 patients with gastric ulcers and 52 healthy subjects were the control groups. The immunohistochemical study was performed to evaluate the protein expression over gastric cancer tissue slides.

RESULTS

The mean SAA concentration was higher in gastric cancer patients (88.54 +/- 50.44 mg/l) than in healthy subjects (3.36 +/- 2.29 mg/l) and gastric ulcer patients (10.48 +/- 8.97 mg/l) (P < .05). The SAA concentration was associated with tumor stage (P = .0244) and location (P = .0016) but not with Lauren's histological type (P = .839). In the multivariate analysis, SAA level was correlated with tumor location (P < .0001) and lymph node status (P < .05). During follow-up, the mean SAA concentration increased significantly in 24 patients with tumor recurrence (P < .05) but did not change in 77 patients without recurrence. In the survival analysis, patients with SAA levels > 97 mg/l had a nearly fourfold increase in risk of death. Immunoreactivity was most prominent in blood vessel regions but not within cancer cells.

CONCLUSIONS

These data not only demonstrated SAA was useful in predicting survival of patients with gastric cancer, but they also showed that SAA was a valuable tool for postoperative follow-up.

Identification of a plasma proteomic signature to distinguish pediatric osteosarcoma from benign osteochondroma

Osteosarcoma (OS) is the most common malignant bone tumor in children. To identify a plasma proteomic signature that can detect OS, we used SELDI MS to perform proteomic profiling on plasma specimens from 29 OS and 20 age-matched osteochondroma (OC) patients. Nineteen statistically significant ion peaks that were differentially expressed in OS when compared with OC patients were identified (p < 0.001 and false discovery rate < 10%). Using the proteomic profiles, we constructed a multivariate 3-nearest neighbors classifier to distinguish OS from OC patients with a sensitivity of 97% and a specificity of 80% based on external leave-one-out crossvalidation. Permutation test showed that the classification result was statistically significant (p < 0.00005). One of the proteins (m/z 11 704) in the proteomic signature was identified as serum amyloid protein A (SAA) by PMF. The higher plasma level of SAA in OS patients was further validated by Western blotting when compared to that of osteochrondroma patients and normal subjects as reference. The classifier based on this plasma proteomic signature may be useful to differentiate malignant bone cancer from benign bone tumors and for early detection of OS in high-risk individuals.

Correlation between serum prostate-specific antigen and alpha-1-antitrypsin in men without and with prostate cancer

Prostate specific antigen (PSA) is frequently used for prostate cancer (PCa) screening, but serum levels are also increased by prostate inflammation. Elevations in serum levels of alpha1-antitrypsin (ATT), a marker of inflammation, in cancer patients are well documented. However, an association between PSA and ATT has never been investigated. The authors, therefore, measured serum acute phase proteins (APPs) ATT, alpha1-acid glycoprotein, C-reactive protein, and alpha1-antichymotrypsin in 174 men without and 34 with newly diagnosed untreated PCa (38-80 years old). As expected, men with PCa had higher mean PSA levels than those without PCa (P < 0.00001). Men with PCa and those without PCa but with PSA >2 ng/mL (n = 68) had significantly higher ATT concentrations than those without these conditions (n = 106) (mean +/- SEM g/L): 1.94+/-0.083, 1.92+/-0.066, 1.25+/-0.043, respectively; p <0.005). Interestingly, African-American men without PCa (n=111) had higher ATT levels than Caucasian men (n=63) (1.565+/-0.045 g/l versus 1.395+/-0.056 g/l; p <0.005); and differences persisted in men with PSA >2 ng/ml (2.094+/-0.07 g/l versus 1.593 for all0.095 g/l; p<0.0002). There were no differences among groups in the levels of other APP. ATT showed the strongest correlation with PSA (r = 0.346 to 0.395; p <0.001) than any other APP (r < or =0.245). Our data suggest that men with PCa have higher ATT levels than those without PCa; and African-American men without PCa have higher ATT levels than Caucasian men. The possible implications of elevated ATT levels in African-American men on the risk of PCa are discussed.

Distinctive serum protein profiles involving abundant proteins in lung cancer patients based upon antibody microarray analysis

Background

Cancer serum protein profiling by mass spectrometry has uncovered mass profiles that are potentially diagnostic for several common types of cancer. However, direct mass spectrometric profiling has a limited dynamic range and difficulties in providing the identification of the distinctive proteins. We hypothesized that distinctive profiles may result from the differential expression of relatively abundant serum proteins associated with the host response.

Methods

Eighty-four antibodies, targeting a wide range of serum proteins, were spotted onto nitrocellulose-coated microscope slides. The abundances of the corresponding proteins were measured in 80 serum samples, from 24 newly diagnosed subjects with lung cancer, 24 healthy controls, and 32 subjects with chronic obstructive pulmonary disease (COPD). Two-color rolling-circle amplification was used to measure protein abundance.

Results

Seven of the 84 antibodies gave a significant difference (p < 0.01) for the lung cancer patients as compared to healthy controls, as well as compared to COPD patients. Proteins that exhibited higher abundances in the lung cancer samples relative to the control samples included C-reactive protein (CRP; a 13.3 fold increase), serum amyloid A (SAA; a 2.0 fold increase), mucin 1 and α-1-antitrypsin (1.4 fold increases). The increased expression levels of CRP and SAA were validated by Western blot analysis. Leave-one-out cross-validation was used to construct Diagonal Linear Discriminant Analysis (DLDA) classifiers. At a cutoff where all 56 of the non-tumor samples were correctly classified, 15/24 lung tumor patient sera were correctly classified.

Conclusion

Our results suggest that a distinctive serum protein profile involving abundant proteins may be observed in lung cancer patients relative to healthy subjects or patients with chronic disease and may have utility as part of strategies for detecting lung cancer.

Expression of serum amyloid A, in normal, dysplastic, and neoplastic human colonic mucosa: implication for a role in colonic tumorigenesis

Serum amyloid A (SAA) is an acute phase reactant, whose level in the blood is elevated in response to trauma, infection, inflammation, and neoplasia. Elevated levels of SAA in the serum of cancer patients were suggested to be of liver origin rather than a tumor cell product. The role of SAA in human malignancies has not been elucidated. We investigated the expression of SAA at various stages of human colon carcinoma progression. Nonradioactive in situ hybridization applied on paraffin tissue sections from 26 colon cancer patients revealed barely detected SAA mRNA expression in normal looking colonic epithelium. Expression was increased gradually as epithelial cells progressed through dysplasia to neoplasia. Deeply invading colon carcinoma cells showed the highest levels of SAA. Expression was also found in colon carcinoma metastases. Cells of lymphoid follicles of the intestinal wall, inflammatory cells, ganglion cells, and endothelial cells, also expressed SAA mRNA. Immunohistochemical staining revealed SAA protein expression that colocalized with SAA mRNA expression. RT-PCR analysis confirmed the expression of the SAA1 and SAA4 genes in colon carcinomas, expression that was barely detectable in normal colon tissues. These findings indicate local and differential expression of SAA in human colon cancer tissues and suggest its role in colonic tumorigenesis.

Identification of serum amyloid A as a biomarker to distinguish prostate cancer patients with bone lesions

BACKGROUND

Prostate cancer has a propensity to metastasize to the bone. Currently, there are no curative treatments for this stage of the disease. Sensitive biomarkers that can be monitored in the blood to indicate the presence or development of bone metastases and/or response to therapies are lacking. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) is an affinity-based approach that allows sensitive and high-throughput protein profiling and screening of biological samples.

METHODS

We used SELDI-TOF MS for protein profiling of sera from prostate cancer patients (n = 38) with and without bone metastases in our effort to identify individual or multiple serum markers that may be of added benefit to those in current use. Serum was applied to ProteinChip surfaces (H4 and IMAC) to quickly screen samples and detect peaks predominating in the samples obtained from patients with bone metastases. Unique proteins in the bone metastasis cohort observed by SELDI-TOF MS were identified by two-dimensional gel electrophoresis, in-gel trypsin digestion, and tandem MS. The identities of the proteins were confirmed by ELISA and immunodepletion assays.

RESULTS

The cluster of unique proteins in the sera of patients with bone metastases was identified as isoforms of serum amyloid A. Machine-learning algorithms were also used to identify patients with bone metastases with a sensitivity and specificity of 89.5%.

CONCLUSIONS

SELDI-TOF MS protein profiling in combination with other proteomic approaches may provide diagnostic tools with potential clinical applications and serve as tools to aid in the discovery of biomarkers associated with various diseases.

Identification of Serum Amyloid A Protein As a Potentially Useful Biomarker to Monitor Relapse of Nasopharyngeal Cancer by Serum Proteomic Profiling

PURPOSE

Nasopharyngeal cancer (NPC) is a common cancer in Hong Kong, and relapse can occur frequently. Using protein chip profiling analysis, we aimed to identify serum biomarkers that were useful in the diagnosis of relapse in NPC.

EXPERIMENTAL DESIGN

Profiling analysis was performed on 704 sera collected from 42 NPC patients, 39 lung cancer patients, 30 patients with the benign metabolic disorder thyrotoxicosis (TX), and 35 normal individuals (NM). Protein profile in each NPC patient during clinical follow up was correlated with the relapse status.

RESULTS

Profiling analysis identified two biomarkers with molecular masses of 11.6 and 11.8 kDa, which were significantly elevated in 22 of 31 (71%) and 21 of 31 (68%) NPC patients, respectively, at the time of relapse (RP) as compared with 11 patients in complete remission (CR; RP versus CR, P = 0.009), 30 TX (RP versus TX, P < 0.001), or 35 NM (RP versus NM, P < 0.001). The markers were also elevated in 16 of 39 (41%) lung cancer patients at initial diagnosis. By tryptic digestion, followed by tandem mass spectrometry fragmentation, the markers were identified as two isoforms of serum amyloid A (SAA) protein. Monitoring the patients longitudinally for SAA level both by protein chip and immunoassay showed a dramatic SAA increase, which correlated with relapse and a drastic fall correlated with response to salvage chemotherapy. Serum SAA findings were compared with those of serum Epstein-Barr virus DNA in three relapsed patients showing a similar correlation with relapse and chemo-response.

CONCLUSIONS

SAA could be a useful biomarker to monitor relapse of NPC.

Serum amyloid A (SAA) variations in patients with cancer: correlation with disease activity, stage, primary site, and prognosis

Serum amyloid A (SAA) was determined in 160 patients with cancer. Active disease was associated with high titre compared with the titre in non-active condition (31.8 v 5.8 micrograms/ml, respectively; p = 0.0002). SAA value showed a direct correlation with the stage of the disease: it was lowest at stages 1 and 2 and highest at the metastatic stage 4 (stage 1 v 4, p = 0.001; stage 2 v 3, p = 0.05). Cancers of the lung and unknown primary site were characterised by highly increased SAA concentration. Initial SAA value had prognostic significance: a value below 10 micrograms/ml correlated with survival advantage, whereas a higher initial value indicated a greater likelihood of a poor outcome (actuarial survival analysis p less than 0.001). When stage was accounted for, initial SAA value had significant prognostic bearing on survival of patients with advanced disease (stages 3 and 4) but not on that of patients with limited disease (stages 1 and 2). Serial testing showed good concordance between changes in SAA titre and clinical course.