Annals of Surgical Oncology Sign the Guestbook
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
10.1245/s10434-006-9091-z
Annals of Surgical Oncology 14:84-93 (2007)
© 2007 Society of Surgical Oncology
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chan, D.-C.
Right arrow Articles by Chen, J.-H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chan, D.-C.
Right arrow Articles by Chen, J.-H.

Original Article

Evaluation of Serum Amyloid A as a Biomarker for Gastric Cancer

De-Chuan Chan, MD1, Cheng-Jueng Chen, MD1, Heng-Cheng Chu, MD2, Wei-Kuo Chang, MD2, Jyh-Cherng Yu, MD1, Yu-Ju Chen3, Li-Li Wen4, Su-Ching Huang5, Chih-Hung Ku6, Yao-Chi Liu, MD1 and Jenn-Han Chen, MD5

1 Division of General Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
2 Division of Gastroenterology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
3 Institute of Chemistry, Academia Sinica, Taipei, Taiwan
4 Department of Clinical Laboratory, En Chu Kong Hospital, Taipei, Taiwan
5 Department of Dentistry, Tri-Service General Hospital, National Defense Medical Center, National Defense University, Taipei, 114, Taiwan
6 School of Public Health, National Defense Medical Center, Taipei, Taiwan

Correspondence: Address correspondence and reprint requests to: De-Chuan Chan, MD; E-mail: chrischan1168{at}yahoo.com.tw, Jenn-Han Chen, MD; E-mail: jhc.ndmc{at}msa.hinet.net


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
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.

Key Words: Serum amyloid A (SAA) protein • Stomach neoplasm • Serum marker • Mass spectrometry (MS)


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Gastric cancer is one of the most common malignancies in Asia.1,2 Currently, the most effective treatment for gastric cancer is surgical resection, but the prognosis is still poor because of advanced disease at diagnosis.3 Identifying early-stage lesions is vital to achieving a high survival rate. In our previous study,4 we investigated five different cancer cell lines in a tumor xenotransplantation model of nude mice and used comparative proteomic technology to identify protein profiles present in the serum of transplantable mice. We identified a unique plasma protein, serum amyloid A (SAA), which appears only in mice transplanted with a gastric cancer cell line (SC-M1).5 This result suggested that SAA could be used as a biomarker for the diagnosis of gastric cancer.

SAA is a major, acute-phase protein synthesized in the liver. It appears at low concentration in the serum of healthy individuals and is upregulated in patients with inflammation or various malignancies.6 An association has been postulated between high SAA concentration and malignant diseases, including lung cancer,7 renal cell carcinoma,8 colorectal cancer,9 prostate cancer,10 nasopharyngeal cancer,11 and breast cancer.12 Moreover, in patients with certain solid malignancies, the SAA concentration increases in the advanced stage or recurrence of disease and in distant metastasis,13 suggesting that SAA is involved in the progression of cancer and may have prognostic value for several types of malignancies.

Based on the work of others and our previous study,4 we propose that SAA might be a good serum biomar-ker for the detection of gastric cancer and its recurrence. To our knowledge, no reports have focused on the relationship between SAA and gastric cancer. We analyzed serum samples from patients with gastric cancer using two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry (MS) identification. We measured SAA concentration by an enzyme immunoassay system in patients with gastric cancer to examine whether it is related to clinical–pathological characteristics and compared SAA concentrations in patients with gastric cancer, patients with gastric ulcers, and healthy subjects.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Patient Population
One hundred and thirty-nine patients with histo-logically confirmed gastric adenocarcinoma were enrolled onto this study between January 2002 and January 2004. All patients received preoperative staging, including chest X-ray, abdominal computed tomography (CT), and bone scan, to exclude the possibility of distal metastasis. Some patients underwent prelaparotomy laparoscopy for detection of peritoneal dissemination. Because SAA concentration is elevated in most infectious or inflammatory condition, patients with obvious infectious or inflammatory disease were excluded from this study. Ninety-six patients without distant metastasis or peritoneal dissemination were enrolled.

Serum samples were drawn from these patients 1 day before surgery. The procedure was approved by the Review Boards of the Tri-Service General Hospital (TSGH), National Defense Medical Center. The average age [± standard deviation (SD)] of patients was 69.11 ± 13.66 years, and 61 men and 35 women were enrolled (Table 1Go). No patient had received chemotherapy, radiotherapy, or immuno-modulatory agents before surgery. All patients underwent curative gastrectomy, including subtotal or total gastrectomy with D2 lymphadenectomy. Curative resection means that there was no residual tumor and a high probability of cure. Curability of gastric resection was defined according to the General Rules for the Gastric Cancer Society, 12th edition, by the Japanese Research Society for Gastric Cancer.14 Thirty-one patients had stage I or II disease, and 65 patients had stage III or IV disease (Table 2Go) according to the revised TNM Classification of Malignant Tumors, 5th edition, by the International Union Against Cancer (UICC).15 The histological type was categorized as the intestinal or diffuse type according to Lauren’s classification.16 Patients were followed after discharge at 3-month intervals for the first 2 years and at 6-month intervals thereafter. Evaluation consisted of medical history, physical examination, blood routine, chest X-ray, abdominal sonography, and tumor markers such as carcinoem-bryonic antigen (CEA) and cancer antigen (CA) 19-9 at every follow-up visit. Bone scan, abdominal CT, and gastroscopy were also conducted at 6-month intervals. Recurrence was defined as clinical and radiological signs of disease with or without histological proof.


View this table:
[in this window]
[in a new window]

  		TABLE 1. Demographic data of patients with gastric cancer, patients with gastric ulcers, and healthy subjects
 

View this table:
[in this window]
[in a new window]

  		TABLE 2. Serum amyloid A (SAA) concentration in patients with gastric cancer, patients with gastric ulcer, and healthy subjects
 
SAA concentration was measured again in 83 patients who were available 1 month postoperatively and in 77 of these patients who were available 6 months postoperatively. Recurrence was confirmed in 24 patients by diagnostic imaging or surgery at the end of the study, and SAA concentration was measured. Normal control serum was obtained from 52 individuals who were proven healthy by routine checks, such as serological examination, urinalysis, chest radiography, electrocardiography, abdominal sonography, and gastroscopy at the Health Care Center of TSGH. In addition, serum samples were collected from 35 patients with benign gastric ulcers proven by endoscopy, with biopsy as another disease control. Informed consent was obtained from all patients and healthy persons in the study.

Two-Dimensional Gel Electrophoresis and Mass Spectrometry Analysis
We performed 2-DE using the isoelectric focusing (IEF) system (IPGphor; Amersham Pharmacia Biotec, Freiburg, Germany) and PROTEAN II MULTI-CELL electrophoresis chamber (Bio-Rad; Hercules, CA, USA).17 Serum samples were solubilized in 350 µl lysis buffer containing 7 M urea (Boehringer, Mannheim, Germany), 4% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) (J.T. Baker, Phillipsburg, NJ, USA), and Tri-N-butylphosphine (TBP; SHOWA, Tokyo, Japan). After sonication, 500 µg of protein was loaded into immobilized pH gradient (IPG) gel strips (pH 3–10 or pH 4–7, 18-cm long, Amersham Biosciences, Uppsala, Sweden). The IPG strips were rehydrated overnight in a solution of 8 M urea, 4% CHAPS, 2% IPG ampholyte, 65 mM dithioerythritol (DTE), 5 mM TBP, and 0.0002% bromophenol blue before use. The IEF system was run at 18°C at 6,000 V for 35 kV/h. After IEF, the IPG strips were equilibrated for 15 min in buffer containing 50 mM Tris (hydroxymethyl) aminomethane hydrochloride (Tris–HCl), pH 8.8, 6 M urea, 2% Sodium dodecyl sulfate (SDS), 30% glycerol, 2% DTE, and attached with 0.5% agarose to the top of a vertical 8–18% linear gradient SDS–polyacrylamide gel. A 2-DE was run at 45 mA for 5 h. The gels were fixed in 10% methanol and 7% acetic acid for 30 min, stained in 400 ml SYPRO Ruby solution overnight, and soaked in deionized water for 20 min. The 2-DE images were scanned using fluorescence image scanning Typhoon 9200 (Amersham Pharmacia Biotech) and analyzed by ImageMaster software (Amersham Biosciences). Protein spots of interest were digested with trypsin using the ProGest workstation (Genomic Solutions, Ann Arbor, MI, USA) with the long trypsin protocol supplied with the instrument.

For the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis,4 peptide powders were resuspended with 0.1 trifluoroacetic acid in 50% acetonitrile and then mixed with matrix (10 mg/ml {alpha}-cyano-4-hydroxycinnamic acid), and analyzed using an Voyager-DE-PRO mass spectrometer (PerSeptive Biosystem, Foster City, CA, USA). The liquid chromatography tandem mass spectrometric (LC–MS/MS) analysis used an UltiMate capillary LC system (LC Packings) coupled to a QSTAR Pulsar i quadrupole time-of-flight mass spectrometer (Applied Biosystem/MDS SCIEX).

Measurement of SAA Concentration
Preoperative blood samples from 96 patients undergoing gastrectomy for gastric cancer were collected. Blood was obtained from 32 patients with gastric ulcers and 52 healthy subjects, who served as the control groups. The blood sample was centrifuged (Kubota, Osaka, Japan) at 3,100 g for 10 min and stored at –20°C until analyzed. Serum was collected for proteomic analysis by 2-DE and MS. The concentration of SAA was measured using a latex particle-enhanced immunonephelometric assay on a nephelometer (Dade Behring Inc., Marburg, Germany). The cutoff value for normal SAA was set at 6.4 mg/l, as indicated in the instructions supplied with the kits.

Immunohistochemistry
Tumors were immunohistochemically stained to locate cells expressing SAA. Tissue specimens were fixed in 4.5% buffered formaldehyde for at least 24 h then embedded in paraffin. Sections (3- to 4-µm thick) were cut on a microtome and mounted onto adhesive-treated glass slides. The paraffin was removed, and mounted sections were rehydrated with descending concentrations of aqueous ethanol. The sections were immersed in DAKO ChemMate Buffer (DAKO, Glostrup, Denmark) and heated in boiling water for 30 min to retrieve antigen. The sections were kept for 15 min at room temperature and subsequently immunostained with primary monoclonal antibodies against SAA (DAKO). The immunoreaction was revealed using the LSAB2 kit and horseradish peroxidase (DAKO) by a standard immunoperoxidase staining method.

Statistical Analysis
SAS 8.0 statistical software was used for statistical analysis. Statistical analysis included the {chi}2 test, Student’s t test, simple linear regression, and one-way analysis of variance (ANOVA). Univariate analyses were performed using a Student’s t test to assess the differences in the protein concentrations between patients with gastric cancer, patients with ulcers, and healthy subjects. The Student’s t test was also used to examine the relationships between protein concentration and clinical–pathological features of gastric cancer, such as age, gender, tumor size, tumor location, Lauren’s histological classification, depth of cancer invasion (T), lymph node metastasis (N), and TNM stage. In addition, a cutoff point for SAA was determined by inspection of martingale residual plots and further assessed in the Cox proportional hazards regression. Survival distribution curves were estimated using Kaplan–Meier methods and compared with the log-rank test. P < .05 was considered statistically significant.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
The 2-DE protein profile of serum proteins from patients with gastric cancer was similar to that of mouse serum reported in our previous study,4 suggesting a similarity in serological variables between the animal model and human patients. Spots 1 and 2 were identified in one gastric cancer patient (Fig. 1Go). Their tryptic peptides, determined using the MS techniques by peptide mass fingerprinting and tandem MS sequencing, matched those predicted for SAA (Fig. 2Go; the corresponding amino acid sequences are underlined). The MS sequence coverage was as high as 57%. As shown in Fig. 3Go, SAA levels detected by enzyme-linked immunosorbent assay (ELISA) correlated with those detected by 2-DE electrophotogram analysis. To verify the linearity of the ELISA, we analyzed dilutions of serum from a patient with gastric cancer with a high level of SAA. There was complete correlation between the dilutions and the levels detected by ELISA (data not shown). Moderate or strong intensities were demonstrated in serum from 71 patients with gastric cancer.


Figure 1
View larger version (29K):
[in this window]
[in a new window]

  		FIG. 1. Gel view of two-dimensional gel electrophoresis (2-DE) electrophotogram of serum from a healthy control subject (a) and a patient with gastric cancer (b). The isoelectric focusing (IEF) was for pH 3–10. Upregulated proteins (spots) in serum from a cancer patient subjected to further analysis and identification by mass spectrometry (MS) using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) are marked.

 

Figure 2
View larger version (12K):
[in this window]
[in a new window]

  		FIG. 2. Identification of serum amyloid A (SAA) by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). MALDI-TOF-MS mass spectrum of the spots shown in Fig. 1Go from the gastric cancer patient is shown (a). The unique cluster of proteins was identified as SAA according to the matched peaks at 15.5 kDa marked by the asterisk (*). The amino acid sequence of SAA in the patient with gastric cancer (b). The identified tryptic peptide sequences are underlined.

 

Figure 3
View larger version (41K):
[in this window]
[in a new window]

  		FIG. 3. Two-dimensional gel electrophoresis (2-DE) electrophotogram of serum of the patient with gastric cancer. Three different intensities of serum amyloid A (SAA) production are evident in samples from the three patients with gastric cancer: Strong intensity [103.7 mg/l by enzyme-linked immunosorbent assay (ELISA)] (a); moderate intensity (33.5 mg/l) (b); weak intensity (3.8 mg/l) (c).

 
Preoperative Serum SAA Levels
As shown in Table 1Go, the SAA concentration of 96 patients with gastric cancer was 88.54 ± 50.44 mg/l (mean ± SD), which was significantly higher than that of 32 gastric ulcer patients (10.48 ± 8.97 mg/l, P = .037) and 52 healthy controls (3.36 ± 2.29 mg/ l, P = .018) (Student’s t test). The concentration was higher than the cutoff values of 6.4 mg/l in 71 (74%) of 96 patients with gastric cancer, nine (28%) of 32 patients with gastric ulcers, and ten (19%) of 52 healthy controls (Table 2Go).

Table 3Go shows the further analysis of the SAA concentration and clinical–pathological features in patients with gastric cancer. Age and gender were not significantly related to concentration (P > .05). Tumor size was significantly related to concentration: for each 1-mm increase in tumor size, SAA concentration increased by 2.10 mg/l (P = .0002, Table 3Go). The mean concentration was higher in 29 patients whose gastric cancer was located in the upper portion than in the other gastric cancer patients (P = .0016). Fifty-two patients were diagnosed with lymph node metastasis by histological examination, and 55 patients had serosal invasion (T3) or invasion in an adjacent organ (T4), as determined by intraoperative findings or histological examination. Patients with serosal invasion or lymph node involvement had significantly higher concentrations than those without such involvement (P < .05). The 65 patients with advanced gastric cancer (stages III and IV) had significantly higher concentrations than the 31 patients with less-advanced disease. The mean concentration of the 12 patients with early gastric cancer (T1), defined according to Japanese Society of Gastrointestinal Endoscopy15, was 28.27 ± 15.23 mg/l, which was higher than that of healthy subjects and patients with gastric ulcer. SAA concentration was not significantly related to Lauren’s histological type. In multivariate analysis, we found that position and lymph node stages were significantly associated with SAA. Patients with proximal gastric cancer have highly significant SAA concentration compared with patients with distal cancer (P < .0001, Table 4Go). In addition, SAA concentration in patients with N0 and N1 were significantly lower than in those with N3: P = .0001 and P = .0340, respectively (Table 4Go).


View this table:
[in this window]
[in a new window]

  		TABLE 3. Serum amyloid A (SAA) concentration and clinical–pathological features of patients with gastric cancer
 

View this table:
[in this window]
[in a new window]

  		TABLE 4. Relationship between serum amyloid A (SAA) concentrations and stomach cancer parameters
 
Changes in SAA Concentration After Tumor Resection
We determined SAA concentrations in 83 patients with gastric cancer 1 month after curative resection of the tumors. Regardless of the original stages of the tumors, the mean concentration decreased significantly to 3.38 ± 2.79 mg/l, which was similar to the concentration in healthy controls (Fig. 4Go). We also measured SAA concentration six months after surgery in 77 patients whose concentrations had been checked preoperatively and 1 month postoperatively. Six months after surgery, the mean concentration was 5.21 ± 2.54 mg/l, and we found no evidence of recurrence in these patients (Fig. 4Go).


Figure 4
View larger version (14K):
[in this window]
[in a new window]

  		FIG. 4. Serial follow-up of serum amyloid A (SAA) concentration before and after curative resection in patients with gastric cancer. The concentration decreased significantly 1 month after resection in 83 patients. The values at 1 month and 6 months after resection did not differ significantly in patients without clinical recurrence. In patients with recurrent cancer, SAA concentration increased significantly compared with the value 6 months after resection. * P < .05 by independent Student’s t test.

 
SAA in Patients with Recurrent Cancer
There were 24 patients with recurrent gastric cancer after curative resection during postoperative follow-up (mean follow-up period 14.6 months; range 6–24 months). These 24 patients comprised five with liver metastasis, ten with peritoneal metastasis, three with bone metastasis, and six with lymph node metastasis. All metastases were confirmed by CT, cytology of ascites, or reexploration. The level of SAA was measured, and recurrent cancer was confirmed. The mean concentration was 170.34 ± 61.72 mg/l, which differed significantly (P < .05) from the concentration in patients whose cancer was did not recur (Fig. 4Go). SAA concentration did not differ significantly according to site of recurrence. Of the 24 patients with recurrent gastric cancer, 20 (83%) exhibited SAA concentrations higher than the cutoff value.

SAA and Survival
Using a univariate Cox proportional hazards model with SAA as a continuous variable, higher levels of SAA were shown to be associated with shorter survival time (P = .002). As expected, univariate Cox models confirmed the correlations between shorter survival times in relation to lymph node metastasis (P = .012) and invasion depth (P = .005). Using the Martingale residual plot for SAA, a cutoff point of 97 mg/l was used to separate the patients into two groups—one with high expression and one with low expression. The risk of death in patients with SAA level greater double equals 97 mg/l was increased more than threefold (95% confidence interval, 0.108–0.605; P = .0019; Fig. 5Go).


Figure 5
View larger version (12K):
[in this window]
[in a new window]

  		FIG. 5. Kaplan–Meier curve showing significantly shorter survival for patients with high levels of serum amyloid A (SAA) (P = .0019, log-rank test).

 
Immunohistochemistry of SAA Expression
To validate the upregulation of SAA, we performed an immunohistochemical study. Immunohistochemical staining demonstrated visible immunoreactivity for SAA on resected tumor specimens from patients with gastric cancer. Immunoreactivity was most prominent in blood vessel regions but not within the cancer cells (Fig. 6Go).


Figure 6
View larger version (58K):
[in this window]
[in a new window]

  		FIG. 6. Immunohistochemistry of the specimen of a gastric tumor. The section (B) was stained with anti-serum-amyloid-A (SAA) antibody and photographed at x200 magnification. SAA was stained prominently in blood vessels (C) but not in cancer cells (A).

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
We evaluated the SAA concentration in patients with gastric cancer, whose mean concentration was significantly higher than that of healthy controls and patients with gastric ulcers (P < .05). SAA concentration decreased 1 month after curative tumor resection and did not increase significantly during the 6-month follow-up in patients without clinical recurrence (P < .05). In contrast, in patients whose cancer recurred, the concentration was significantly higher at the time of recurrence than at 1 month after resection (P < .05). These findings suggest that SAA may have a role as a biomarker during the postsurgical care of patients with gastric cancer.

SAA, produced mainly in the liver, is called a "first-class," acute-phase reactant because it is the most sensitive plasma protein indicating inflammatory activity.6 A previous study18 reported healthy subjects have low concentrations, which is consistent with data in our study. The protein has received considerable attention as a potential marker for neoplastic activity because its concentration increases in patients with lung, renal, colorectal, breast, and other forms of cancer.7–13 In our study, the SAA concentration was 30 times higher than normal in patients with gastric cancer. The sensitivity (74%) of SAA in our study was higher than that reported using conventional tumor markers for gastric cancer (e.g., 20–50% for CEA, CA 19-9, and CA 125).19–24 We believe that it might be a useful new biomarker for detecting gastric cancer.

SAA concentrations in our patients reflected disease status, such as tumor size, location, invasion depth, lymph node metastasis, clinical stage, and tumor recurrence, suggesting that it might predict cancer status. Similar results have been reported in other cancer patients. Rosenthal and Sullivan found a positive correlation between SAA concentration and the presence of distant metastatic disease in patients with a variety of solid tumors—in particular, lung cancer.13 Biran et al. found that SAA concentration is directly correlated with disease stage.7 O’Hanlon et al. found the highest concentrations of SAA in patients with ulcerating T4 breast cancer.12 Cho et al. found that SAA concentration can be used to monitor nasopharyngeal cancer relapse.11 Rosenthal and Sullivan reported that SAA concentration was positively correlated with the size of the primary tumor in 85% of their patients,13 a finding that is similar to our data showing that each 1-mm increase in tumor size was accompanied by a 2.10- mg/l increase in concentration (P = .0002, Table 3Go). In our series, SAA concentration was significantly higher in patients with lymph node metastasis or serosal invasion than in those without, suggesting that advanced T and N tumors might be predicted for patients with higher preoperative concentration. Moreover, patients with gastric cancer in the upper region had significantly higher concentrations than those with cancers in middle and lower locations.

The association between chronic Helicobacter pylori infection and growth of gastric cancer is well established,25,26 and distal gastric cancer is more strongly associated with H. pylori infection.27 Nevertheless, Delanghe et al. detected that there is no significant correlation between SAA concentration and H. pylori infection.28 We did not differentiate the association between SAA concentrations and H. pylori infection in this study; however, patients with distal gastric cancer have lower SAA concentrations than those with proximal gastric caner, which suggested the protein may be independent of H. pylori infection.

Our results suggest that tumorigenesis of gastric cancer might increase SAA production although the mechanisms underlying the association between increased concentration and cancer have not been identified. It is uncertain whether the cancer cells secrete SAA or whether SAA secretion is mediated via another type of tissue response. Our study using immunohistochemical staining demonstrated that immunoreactivity was most prominent in blood vessel regions but not in cancer cells (Fig. 5Go). Therefore, SAA does not appear to be a tumor-derived product but a host-generated substance. This has been reported previously in patients with nasopharyngeal cancer.11 One possible explanation of the relationship between SAA and cancer is that interleukin 6 (IL-6), a potent proinflammatory cytokine, is a principal regulator of SAA production.29 Clinical research has shown increased serum IL-6 concentration in patients with gastric cancer.30–35 It is also possible that gastric cancer cells secrete IL-6.36,37 Wu et al.33 reported that five of six gastric cancer cell lines could secrete IL-6 at concentrations ranging from 0.4 pg/ml to more than 13 pg/ml; the IL-6 concentration produced by the SC-M1 cell line was 13 pg/ ml. Interestingly, unlike patients with gastric cancer, the 32 patients with gastric ulcers in our study did not have elevated SAA concentration, suggesting that the two conditions generate different cytokine profiles and the potential value of SAA in distinguishing between the two conditions.

In our previous study,4 we transplanted five different cancer cell lines into nude mice and used comparative proteomic technology to display the serum protein profile. We identified SAA only in sera of nude mice transplanted with SC-M1 gastric cancer cell line, suggesting that different types of cancer cells have different abilities to induce SAA production. Similarly, Biran et al.7 and Rosenthal and Sullivan13 noted that cancers of the lung seem to produce more SAA than do breast and colorectal cancers. This implies that the heterogeneity of the cancer may induce various degrees of the acute-phase response, probably through different immunological mechanisms in the host.

SAA is not considered as a cancer-specific marker because an increased concentration is associated with a broad spectrum of diseases. We did not construct our study to compare SAA concentrations in patients with various types of cancer. Further studies should be performed to identify the protein expression profile of serum from patients with other types cancers and to compare these with samples obtained from patients with gastric cancer in the hope of revealing specific biomarkers for gastric cancer. However, SAA still receives attention as a potential biomarker for malignancy because of a close correlation between elevated concentration and tumor progression, recurrence, and survival. Regardless of the mechanisms that lead to SAA, our current data indicate that SAA levels reflect the clinical behavior of gastric cancer, namely, that higher levels of the marker are associated with more aggressive disease and poor outcome (Fig. 6Go). In, addition, SAA concentration is an ideal marker for postoperative follow-up of gastric cancer patients: SAA concentration returned to normal in our patients when they received curative gastrectomy. SAA concentration might provide a means of evaluating the effectiveness of treatment and of detecting recurrence. We believe that serial measurement of SAA concentration has a potential role in monitoring patients after therapeutic intervention.

In the current study, we demonstrated that patients with gastric cancer have higher SAA concentrations than do patients with gastric ulcers and healthy subjects and that levels of SAA correlate with tumor status, prognosis, and recurrence. We thought that SAA may be a valuable prognostic predictor for gastric cancer and a useful tool during postoperative follow-up in patients with gastric cancer. The biological function of SAA in gastric cancer remains to be investigated.

Received for publication July 7, 2006. Accepted for publication July 7, 2006.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Stadtlander CT, Waterbor JW. Molecular epidemiology, pathogenesis and prevention of gastric cancer. Carcinogenesis 1999; 20:2195–208.[Abstract/Free Full Text]
  2. Health and Vital Statistics. Taipei: Department of Health, Executive Yuan, Republic of China, 1997.
  3. Collard JM, Malaise J, Mabrut JY, et al. Skeletonizing. En--bloc gastrectomy for adenocarcinoma in Caucasian patients. Gastric Cancer 2003; 6:210–16.[CrossRef][Medline]
  4. Juan HF, Chen JH, Hsu WT, et al. Identification of tumor-associated plasma biomarkers using proteomic techniques: From mouse to human. Proteomics 2004; 4:2766–775.[CrossRef][Medline]
  5. Sheu LF, Chen A, Wei YH, et al. Epstein-Barr virus LMP1 modulates the malignant potential of gastric carcinoma cells involving apoptosis. Am J Pathol 1998; 152:63–74.[Abstract]
  6. Yamada T. Serum amyloid A (SAA): a concise review of biology, assay methods and clinical usefulness. Clin Chem Lab Med 1999; 37:381–8.[CrossRef][Medline]
  7. Biran H, Friedman N, Neumann PM, et al. Serum amyloid A (SAA) variations in patients with cancer: correlation with disease activity, stage, primary site, and prognosis. J Clin Pathol 1986; 39:794–7.[Abstract/Free Full Text]
  8. Kimura M, Tomita Y, Imai T, et al. Significance of serum amyloid A on the prognosis in patients with renal cell carcinoma. Cancer 2001; 92(8):2072–5.[CrossRef][Medline]
  9. Glojnaric I, Casl MT, Simic D, et al. Serum amyloid A protein (SAA) in colorectal carcinoma. Clin Chem Lab Med 2001; 39(2):129–33.[CrossRef][Medline]
  10. Kaneti J, Winikoff Y, Zimlichman S, et al. Importance of serum amyloid A (SAA) level in monitoring disease activity and response to therapy in patients with prostate cancer. Urol Res 1984; 12(5):239–41.[Medline]
  11. Cho WC, Yip TT, Yip C, et al. Identification of serum amyloid a protein as a potentially useful biomarker to monitor relapse of nasopharyngeal cancer by serum proteomic profiling. Clin Cancer Res 2004; 10(1 Pt 1):43–52.[Abstract/Free Full Text]
  12. O’Hanlon DM, Lynch J, Cormican M, Given HF. The acute phase response in breast carcinoma. Anticancer Res 2002; 22:1289–93.[Medline]
  13. Rosenthal CJ, Sullivan LM. Serum amyloid A to monitor cancer dissemination. Ann Intern Med 1979; 91:383–90.[Abstract/Free Full Text]
  14. Japanese Research Society for Gastric Cancer. (1993). The General Rules for the Gastric Cancer Study. 12th edn. Tokyo: Kanehara, pp 30–3.
  15. Sobin LH, Wittekind CH. (1997). International Union Against Cancer (UICC): TNM classification of malignant tumors, 5th edn. New York: John Wiley.
  16. Lauren P. The two histological main types of gastric carcinoma: Diffuse and so-called intestinal-type carcinoma. Acta Pathol Microbiol Scand 1965; 64:31–49.[Medline]
  17. Juan HF, Lin JY, Chang WH, et al. Biomic study of human myeloid leukemia cells differentiation to macrophages using DNA array, proteomic, and bioinformatics analytical methods. Electrophoresis 2002; 23:2490–504.[CrossRef][Medline]
  18. d’Eril GM, Anesi A, Maggiore M, et al. Biological variation of serum amyloid A in healthy subjects. Clin Chem 2001; 47:1498–9.[Free Full Text]
  19. Shimizu N, Wakatsuki T, Murakami A. Carcinoembryonic antigen in gastric cancer patients. Oncology 1987; 44:240–4.[Medline]
  20. Nakane Y, Okamura S, Akehira K, et al. Correlation of preoperative carcinoembryonic antigen levels and prognosis of gastric cancer patients. Cancer 1994; 73:2703–8.[CrossRef][Medline]
  21. Koga T, Kano T, Souda K. The clinical usefulness of preoperative CEA determination in gastric cancer. Jpn J Surg 1987; 17:342–7.[CrossRef][Medline]
  22. Sakamoto K, Haga Y, Yoshimura R, et al. Comparative effectiveness of the tumour diagnostics, CA 19-9, CA125 and carcinoembryonic antigen in patients with diseases of the digestive system. Gut 1987; 28:323–9.[Abstract/Free Full Text]
  23. Marrelli D, Roviello F, De Stefano A, et al. Prognostic significance of CEA, CA 19-9 and CA 72-4 preoperative serum levels in gastric carcinoma. Oncology 1999; 57:55–62.[CrossRef][Medline]
  24. Safi F, Kuhns V, Beger HG. Comparison of CA72-4, CA19-9 and CEA in the diagnosis and monitoring of gastric cancer. Int J Biol Markers 1995; 10:100–6.[Medline]
  25. Parsonnet J, Friedman GD, Vandersteen DP, et al. Helicobacter pylori infection and the risk of gastric carcinoma. N Engl J Med 1991; 325:1127–31.[Abstract]
  26. Forman D, Newell DG, Fullerton F, et al. Association between infection with Helicobacter pylori and risk of gastric cancer: evidence from a prospective investigation. BMJ 1991; 302:1302–5.[Abstract/Free Full Text]
  27. Hansen S, Melby KK, Aase S, Jellium E, Vollset SE. Helicobacter pylori infection and risk of cardia cancer and non-cardia cancer. Scand J Gastroenterol 1999; 4:353–60.
  28. Delanghe JR, Langlois MR, De Bacquer D, Mak R, Capel P, Van Renterghem L, De Backer G. Discriminative value of serum amyloid A and other acute-phase proteins for coronary heart disease. Atherosclerosis 2002; 160(2):471–6.[CrossRef][Medline]
  29. Hagihara K, Nishikawa T, Isobe T, et al. IL-6 plays a critical role in the synergistic induction of human serum amyloid A (SAA) gene when stimulated with proinflammatory cytokines as analyzed with an SAA isoform real-time quantitative RT-PCR assay system. Biochem Biophys Res Commun 2004; 314(2):363–9.[CrossRef][Medline]
  30. Galizia G, Lieto E, De Vita F, et al. Circulating levels of interleukin-10 and interleukin-6 in gastric and colon cancer patients before and after surgery: Relationship with radicality and outcome. J Interferon Cytokine Res 2002; 22:473–82.[CrossRef][Medline]
  31. Yamaoka Y, Kodama T, Kita M, et al. Relation between cytokines and Helicobacter pylori in gastric cancer. Helicobacter 2001; 6:116–24.[CrossRef][Medline]
  32. De Vita F, Romano C, Orditura M, et al. Interleukin-6 serum level correlates with survival in advanced gastrointestinal cancer patients but is not an independent prognostic indicator. J Interferon Cytokine Res 2001; 21:45–52.[CrossRef][Medline]
  33. Wu CW, Wang SR, Chao MF, et al. Serum interleukin-6 levels reflect disease status of gastric cancer. Am J Gastroenterol 1996; 91:1417–22.[Medline]
  34. Kabir S, Daar GA. Serum levels of interleukin-1, interleukin-6 and tumor necrosis factor-alpha in patients with gastric cancer. Cancer Lett 1995; 95:207–12.[CrossRef][Medline]
  35. Tatsuno I, Nishikawa T, Sasano H, et al. Interleukin 6-producing gastric carcinoma with fever, hypergammaglobulinemia, and plasmacytosis in bone marrow. Gastroenterology 1994; 107:543–7.[Medline]
  36. Lin MT, Juan CY, Chang KJ, et al. IL-6 inhibits apoptosis and retains oxidative DNA lesions in human gastric cancer AGS cells through up-regulation of anti-apoptotic gene mcl-1. Carcinogenesis 2001; 22:1947–53.[Abstract/Free Full Text]
  37. Ding SZ, Cho CH, Lam SK. Regulation of IL-6 production in human gastric epithelial cell line MKN-28. Cytokine 2000; 12:1129–35.[CrossRef][Medline]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Chan, D.-C.
Right arrow Articles by Chen, J.-H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chan, D.-C.
Right arrow Articles by Chen, J.-H.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS