Measurement of a breast cancer associated antigen detected by monoclonal antibody SP-2 in sera of cancer patients

LGALS3BP is a novel and potential biomarker in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common solid renal tumor. Therefore, it is necessary to explore the related tumor markers. LGALS3BP (galectin 3 binding protein) is a multifunctional glycoprotein implicated in immunity and cancer. Some studies have shown that LGALS3BP promotes the occurrence and development of tumors. However, their exact role in renal tumorigenesis remains unclear. Our study used a webserver to explore the mRNA expression and clinical features of LGALS3BP in ccRCC. Survival analysis showed that patients with high LGALS3BP expression had significantly worse OS and DFS than those with low LGALS3BP expression. LGALS3BP expression is significantly related to B cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells. Furthermore, we determined that LGALS3BP is significantly associated with angiogenesis, stemness and proliferation in renal cancer. Three phenotypes may be associated with a poor prognosis. Genes related to proliferation, angiogenesis and stemness were derived from a Venn diagram of FGF2. FGF2 is negatively correlated with proliferation and positively correlated with angiogenesis. Finally, we screened for drugs that may have potential therapeutic value for ccRCC. The PCR results showed that the expression of LGALS3BP in the normal cell line was lower than that in the tumor cell lines. After LGALS3BP knockdown, the proliferation of 769-P and 786-O cells decreased. The present findings show that LGALS3BP is critical for ccRCC cell proliferation and may be a potential target and biomarker for ccRCC.

Role of galectin 3 binding protein in cancer progression: a potential novel therapeutic target

The lectin galactoside-binding soluble 3 binding protein (LGALS3BP) is a secreted, hyperglycosylated protein expressed by the majority of human cells. It was first identified as cancer and metastasis associated protein, while its role in innate immune response upon viral infection remains still to be clarified. Since its discovery dated in early 90 s, a large body of literature has been accumulating highlighting both a prognostic and functional role for LGALS3BP in cancer. Moreover, data from our group and other have strongly suggested that this protein is enriched in cancer-associated extracellular vesicles and may be considered a promising candidate for a targeted therapy in LGALS3BP positive cancers. Here, we extensively reviewed the literature relative to LGALS3BP role in cancer and its potential value as a therapeutic target.

CA 549 and SP2 in postoperative breast cancer patients. Comparison with CA 15.3, CEA and TPA

The levels of CA 549 and SP2 were measured in 430 subjects: 100 healthy blood donors, 130 patients with benign diseases and 200 postoperative breast cancer patients. In the latter group, the serum levels of CA 15.3, CEA and TPA were also measured. The Kolmogorov-Smirnov, Mann Whitney and McNemar tests were used for statistical analysis. The upper normal limits were established on the basis of the values obtained in the healthy blood donors group, the benign diseases group and R.O.C. analysis of the breast cancer group. They were: CA 549 = 13 U/ml, SP2 = 14 U/ml, CA 15.3 = 35 U/ml, CEA = 5 ng/ml and TPA = 110 U/ml. The sensitivity, specificity and accuracy in the breast cancer group were, respectively: CA 549 = 78.1%, 97.1% and 88%; SP2 = 21.9%, 90.4% and 57.5%; CEA = 66.7%, 95.2% and 81.5%; CA 15.3 = 80.2%, 98.1% and 89.5%, and TPA = 73.9%, 78.8% and 76.5%. Statistical analysis showed significant differences only between CA 15.3, the marker which gave the best results, and SP2 (p<0.001). There were no significant differences with the association of two or three tumor markers.

Are 90K/MAC-2BP Serum Levels Correlated with Poor Prognosis in HCC Patients? Preliminary Results

In this study we assessed the prognostic significance of 90K/MAC-2BP serum levels in a group of 40 hepatocellular carcinoma patients. This glycoprotein is a new, interesting serum marker that reflects the immune reaction of the host against certain viral infections and tumors such as breast, ovarian and pancreatic cancer. Hepatocellular carcinoma (HCC) is one of the most widespread tumors in the world. AFP is currently the most useful marker for HCC, in spite of its poor diagnostic sensitivity. In this study 40 cirrhotic HCC patients were enrolled. The prevalence of viral hepatic infections in this group was 73% for HCV, 8% for HBV, and 8% for both viruses. Thirteen percent of the patients showed non-virus-related liver damage. 90K serum levels were assayed by an ELISA kit and AFP levels by a chemiluminescent enzyme immunometric system. The overall survival curves were estimated by the Kaplan-Meier method, taking into account age, sex, 90K and AFP serum levels. Statistical analysis showed a highly significant influence on overall survival of age below 70 years and 90K serum levels below the cutoff of 14 ng/mL. Serum AFP (≤20 ng/mL) had positive prognostic value only when it was associated with 90K levels (p<0.02, log-rank).

90K immunostimulatory glycoprotein in children with juvenile idiopathic arthritis

OBJECTIVES

To assess whether circulating levels of 90K glycoprotein are increased in children with juvenile idiopathic arthritis (JIA) at different stages of the disease, compared to healthy controls and to evaluate potential over time changes in its concentrations following treatment with the antitumor-necrosis factor (TNF) drug etanercept.

METHODS

90K glycoprotein, C-reactive protein, erythrocyte sedimentation rate, TNF, antinuclear antibodies, rheumatoid factor and the Juvenile Arthritis Disease Activity Score were assessed in 71 children: 23 with newly diagnosed JIA, 23 with established and active JIA and 25 healthy controls. Patients, eligible for anti-TNF treatment, underwent a similar clinical/laboratory assessment after 6- and 12-month etanercept therapy.

RESULTS

At baseline, significant differences were found in 90K levels between the three study groups: JIA at onset (157.7 [131.4-241.5] μg/ml), JIA on treatment (90.0 [68.8-120.2] μg/ml) and control group (58.0 [44.5-79.0] μg/ml), (p for trend <.001), with the JIA at onset group showing the highest values. In the JIA on treatment group, following one-year etanercept treatment, a significant reduction in 90K was detected already at 6 months (74.3 [56.0-104.1] μg/ml p = .001) and a further decline was observed at 12 months (49.3 [46.0-67.6] μg/ml p < .001).

CONCLUSION

Our study showed that 90K glycoprotein levels are increased in JIA children compared to healthy controls, suggesting a potential pathogenetic role in the JIA. Besides, 12 months of therapy with etanercept can reduce 90K levels.

Circulating autoantibodies to LGALS3BP: a novel biomarker for cancer

Purpose. Circulating autoantibodies have been extensively investigated as possible markers for early diagnosis of cancer. The present study was carried out to investigate whether anti-LGALS3BP IgG autoantibodies could be classified as a biomarker for malignant tumors. Methods. An in-house developed enzyme-linked immunosorbent assay was used to detect autoantibodies to LGALS3BP in sera from 71 patients with various types of cancers and 54 healthy subjects matched by age and gender. Results. Patients with cancer have significant higher circulating levels of anti-LGALS3BP antibodies as compared to control subjects (P < 0.001). The test has a sensitivity of 33% and a specificity of 98%. Conclusions. Anti-LGALS3BP IgG autoantibodies are a promising biomarker for malignant tumors and could play a role in the development of a multimarker assay for the early detection of cancer.

Tumor biomarker glycoproteins in the seminal plasma of healthy human males are endogenous ligands for DC-SIGN

DC-SIGN is an immune C-type lectin that is expressed on both immature and mature dendritic cells associated with peripheral and lymphoid tissues in humans. It is a pattern recognition receptor that binds to several pathogens including HIV-1, Ebola virus, Mycobacterium tuberculosis, Candida albicans, Helicobacter pylori, and Schistosoma mansoni. Evidence is now mounting that DC-SIGN also recognizes endogenous glycoproteins, and that such interactions play a major role in maintaining immune homeostasis in humans and mice. Autoantigens (neoantigens) are produced for the first time in the human testes and other organs of the male urogenital tract under androgenic stimulus during puberty. Such antigens trigger autoimmune orchitis if the immune response is not tightly regulated within this system. Endogenous ligands for DC-SIGN could play a role in modulating such responses. Human seminal plasma glycoproteins express a high level of terminal Lewis(x) and Lewis(y) carbohydrate antigens. These epitopes react specifically with the lectin domains of DC-SIGN. However, because the expression of these sequences is necessary but not sufficient for interaction with DC-SIGN, this study was undertaken to determine if any seminal plasma glycoproteins are also endogenous ligands for DC-SIGN. Glycoproteins bearing terminal Lewis(x) and Lewis(y) sequences were initially isolated by lectin affinity chromatography. Protein sequencing established that three tumor biomarker glycoproteins (clusterin, galectin-3 binding glycoprotein, prostatic acid phosphatase) and protein C inhibitor were purified by using this affinity method. The binding of DC-SIGN to these seminal plasma glycoproteins was demonstrated in both Western blot and immunoprecipitation studies. These findings have confirmed that human seminal plasma contains endogenous glycoprotein ligands for DC-SIGN that could play a role in maintaining immune homeostasis both in the male urogenital tract and the vagina after coitus.

The conserved scavenger receptor cysteine-rich superfamily in therapy and diagnosis

The scavenger receptor cysteine-rich (SRCR) superfamily of soluble or membrane-bound protein receptors is characterized by the presence of one or several repeats of an ancient and highly conserved protein module, the SRCR domain. This superfamily (SRCR-SF) has been in constant and progressive expansion, now up to more than 30 members. The study of these members is attracting growing interest, which parallels that in innate immunity. No unifying function has been described to date for the SRCR domains, this being the result of the limited knowledge still available on the physiology of most members of the SRCR-SF, but also of the sequence versatility of the SRCR domains. Indeed, involvement of SRCR-SF members in quite different functions, such as pathogen recognition, modulation of the immune response, epithelial homeostasis, stem cell biology, and tumor development, have all been described. This has brought to us new information, unveiling the possibility that targeting or supplementing SRCR-SF proteins could result in diagnostic and/or therapeutic benefit for a number of physiologic and pathologic states. Recent research has provided structural and functional insight into these proteins, facilitating the development of means to modulate the activity of SRCR-SF members. Indeed, some of these approaches are already in use, paving the way for a more comprehensive use of SRCR-SF members in the clinic. The present review will illustrate some available evidence on the potential of well known and new members of the SRCR-SF in this regard.

Role of STAT3 as a negative regulator in Mac2- binding protein expression

BACKGROUND

Mac-2 binding protein (Mac-2BP) is a secreted glycoprotein from the culture fluid of several human cancer cells, especially breast, lung, and gastric cells. Mac-2BP plays a role in immune response and cell adhesion activity in patients with various cancer and infectious diseases. In this study, we attempted to identify the regulators of Mac-2BP expression at the transcriptional level.

METHODS

To determine the effect of epidermal growth factor (EGF) to Mac-2BP expression in gastric cancers, we constructed the different lengths of Mac-2BP promoter plasmids and measured the promoter activity and Mac-2BP expression. In addition to investigating the role of signal transducer and activator of transcription3 (STAT3) or human telomerase reverse transcriptase (hTERT) as a regulator of Mac-2BP, we transfected the small interfering RNA (siRNA) specific for STAT3 or hTERT, and Mac-2BP level was observed by a quantitative ELISA.

RESULTS

EGF treatment could suppress the Mac-2BP transcription in HEK293 or gastric cancer cell lines (SNU-638 or AGS). In 5'-deleted promoter experiment, pGL3-Mac Pro-2377 transfected cells showed a decreased luciferase activity compared to pGL3-Mac Pro-2277. We also identified that (-2,366/-2,356) on Mac-2BP promoter is a putative STAT3 binding site and suppression of STAT3 with STAT3 specific siRNA increased the Mac-2BP level, suggesting the role of STAT3 as a negative regulator, in contrast to hTERT, which is known as a positive regulator.

CONCLUSIONS

EGF signal is critical for the Mac-2BP expression, and more importantly, STAT3 could work as a negative regulator, while hTERT as a positive regulator in Mac-2BP transcription.

High expression of 90K (Mac-2 BP) is associated with poor survival in node-negative breast cancer patients not receiving adjuvant systemic therapies

90K (Mac-2 BP) expression was evaluated by immunohistochemistry in paraffin-embedded tissue from a consecutive series of lymph-node negative breast cancer patients who did not receive adjuvant systemic treatment. An independent series of patients served as validation set. The association of 90K expression with risk of recurrence and death was examined in survival analyses together with known prognostic factors. High levels of 90K expression (IHC score>8) were observed in 43 (25.3%) of 170 tumors examined. We found elevated risks of distant recurrence and overall mortality in patients with high 90K expression compared with patients with low 90K expression in their tumors. This increase persisted after adjusting for other prognostic factors in multivariate analysis (hazard ratio=4.084; p<0.001 for recurrence; hazard ratio=4.298; p<0.001 for death). These findings were confirmed in the validation set. Therefore, evaluation of 90K expression may be beneficial to identify lymph-node negative breast cancer patients at lower risk of disease recurrence and death.

Upstream stimulatory factor regulates constitutive expression and hormonal suppression of the 90K (Mac-2BP) protein

We previously reported that hormones important for the normal growth and function of FRTL-5 rat thyroid cells, TSH, or its cAMP signal plus insulin or IGF-I, could transcriptionally suppress constitutive and gamma-interferon (IFN)-increased synthesis of the 90K protein (also known as Mac-2BP). Here we cloned the 5'-flanking region of the rat 90K gene and identified a minimal promoter containing an interferon response element and a consensus E-box or upstream stimulator factor (USF) binding site, which are highly conserved in both the human and murine genes. We show that suppression of constitutive and gamma-IFN-increased 90K gene expression by TSH/cAMP plus insulin/IGF-I depends on the ability of the hormones to decrease the binding of USF to the E-box, located upstream of the interferon response element. This site is required for the constitutive expression of the 90K gene. Transfection with USF1 and USF2 cDNAs increases constitutive promoter activity, attenuates the ability of TSH/cAMP plus insulin/IGF-I to decrease constitutive or gamma-IFN-increased 90K gene expression but does not abrogate the ability of gamma-IFN itself to increase 90K gene expression.

Up-regulation of Mac-2 binding protein by hTERT in gastric cancer

Mac-2 binding protein (Mac-2BP) is a secreted tumor antigen that is elevated in many cancers and implicated in tumor metastasis, as well as cell adhesion and immune functions. We focused on the human telomerase reverse transcriptase (hTERT) induced Mac-2BP expression and the relationship between Mac-2BP expression and the progression of gastric cancer. A cDNA expression array analysis was performed on the telomerase-negative cell line, SW13, which was engineered to overexpress hTERT when compared with the parental SW13 cell. hTERT-induced Mac-2BP expression was confirmed via RT-PCR and Northern blotting. ELISA and flow cytometric analyses revealed that Mac-2BP protein was increased by 2- to 4-fold in hTERT-overexpressing cells compared with the mock control. Mac-2BP expression was significantly reduced when the overexpressed hTERT was neutralized by the introduction of hTERT-specific siRNA. These results suggest that Mac-2BP expression is modulated by hTERT. Mac-2BP levels in both gastric cancer cells and tumor tissues were determined via Northern blot analysis and immunohistochemistry. Mac-2BP protein was highly expressed in most gastric cancer cell lines, and gastric tumor tissues were stained more densely than normal tissues. The intracellular and secreted Mac-2BP levels were also evaluated via ELISA, indicating that Mac-2BP was expressed and secreted more abundantly in gastric cancer patients than in healthy donors. The elevated serum Mac-2BP level in gastric tumor patients was also significantly associated with distant metastasis (p = 0.05) and higher tumor stage (p = 0.04). Our findings suggest that Mac-2BP is induced by hTERT, and that it may prove to be a useful prognostic marker for the detection of malignant progression of metastatic stomach cancers.

Suppression of progression and metastasis of established colon tumors in mice by intravenous delivery of short interfering RNA targeting KITENIN, a metastasis-enhancing protein

KITENIN promotes invasion of mouse colon adenocarcinoma (CT-26) cells in vivo. Here, we studied the effects of in vivo KITENIN ablation on established tumors by using pSUPER vectors (pSUPER-KITENIN) producing short interfering RNA (siRNA). When pSUPER-KITENIN was given weekly or semiweekly for 1 month into tail vein of syngeneic mice that have established colon tumors, tumor size regressed markedly and metastases were inhibited. In mice injected with pSUPER-KITENIN, serum interleukin-2 (IL-2) and IFN-gamma increased and CD4+ and CD8+ T cells infiltrated in the regressed tumor tissues. These effects, observed beginning 2 days after i.v. injection, imply that immune response is involved in the antitumor action of pSUPER-KITENIN. Using a yeast two-hybrid assay, we identified two KITENIN-interacting proteins for the possible mediators of these actions: 90K protein, a known immune modulatory glycoprotein, and protein kinase C inhibitor (PKCI). 90K was increased in the culture medium from CT-26/antisense KITENIN/90K cells. Double culture of accessory cells with CT-26/antisense KITENIN/90K cells revealed increased secretion of IL-1 and IL-6. Overexpression of 90K in CT-26/antisense KITENIN cells further delayed tumor growth compared with that of CT-26/antisense KITENIN cells. Actin arrangement was distorted in CT-26/antisense KITENIN and CT-26/antisense PKCI cells, whereas overexpression of PKCI resulted in increased invasiveness to fibronectin. Thus, antitumor effects of KITENIN siRNA derives from both the generation of a tumor-specific immune response in vivo through increased 90K secretion from tumor cells and the suppression of tumor invasion in which PKCI is related to increased invasiveness. Moreover, siRNA targeting of KITENIN can function as a chemotherapeutic strategy against colon cancer.

Comprehensive proteomic analysis of human pancreatic juice

Proteomic technologies provide an excellent means for analysis of body fluids for cataloging protein constituents and identifying biomarkers for early detection of cancers. The biomarkers currently available for pancreatic cancer, such as CA19-9, lack adequate sensitivity and specificity contributing to late diagnosis of this deadly disease. In this study, we carried out a comprehensive characterization of the "pancreatic juice proteome" in patients with pancreatic adenocarcinoma. Pancreatic juice was first fractionated by 1-dimensional gel electrophoresis and subsequently analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). A total of 170 unique proteins were identified including known pancreatic cancer tumor markers (e.g., CEA, MUC1) and proteins overexpressed in pancreatic cancers (e.g., hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP) and lipocalin 2). In addition, we identified a number of proteins that have not been previously described in pancreatic juice (e.g., tumor rejection antigen (pg96) and azurocidin). Interestingly, a novel protein that is 85% identical to HIP/PAP was identified, which we have designated as PAP-2. The proteins identified in this study could be directly assessed for their potential as biomarkers for pancreatic cancer by quantitative proteomics methods or immunoassays.

90K (Mac-2 BP) and galectins in tumor progression and metastasis

Galectins and their ligands have been implicated in cell transformation and cancer metastasis, and found to have prognostic value. Mac-2 BP, also known as 90K, is a highly glycosylated, secreted protein extensively studied in human cancer, which binds galectin-1, galectin-3 and galectin-7. High expression levels of 90K are associated with a shorter survival, the occurrence of metastasis or a reduced response to chemotherapy in patients with different types of malignancy. The mechanisms underlying the prognostic significance of 90K and galectins in cancer are far from being understood, although they may be related to the ability of these proteins to interact and, to some extent, modulate cell-cell and cell-matrix adhesion and apoptosis. The resulting scenario is even more complex, as data have been presented that all these proteins might be associated with either a positive or a negative outcome of the patients. It is hypothesised that different galectins and galectin ligands with overlapping or opposite functions, expressed in different tumors during the different steps of the metastatic cascade might play a crucial role in tumor progression.

90K (Mac-2 BP) and galectins in tumor progression and metastasis

Galectins and their ligands have been implicated in cell transformation and cancer metastasis, and found to have prognostic value. Mac-2 BP, also known as 90K, is a highly glycosylated, secreted protein extensively studied in human cancer, which binds galectin-1, galectin-3 and galectin-7. High expression levels of 90K are associated with a shorter survival, the occurrence of metastasis or a reduced response to chemotherapy in patients with different types of malignancy. The mechanisms underlying the prognostic significance of 90K and galectins in cancer are far from being understood, although they may be related to the ability of these proteins to interact and, to some extent, modulate cell-cell and cell-matrix adhesion and apoptosis. The resulting scenario is even more complex, as data have been presented that all these proteins might be associated with either a positive or a negative outcome of the patients. It is hypothesised that different galectins and galectin ligands with overlapping or opposite functions, expressed in different tumors during the different steps of the metastatic cascade might play a crucial role in tumor progression.

Proteomic characterization of nipple aspirate fluid: identification of potential biomarkers of breast cancer

Mammary ductal cells are the origin for 70-80% of breast cancers. Nipple aspirate fluid (NAF) contains proteins directly secreted by the ductal and lobular epithelium in non-lactating women. Proteomic approaches offer a largely unbiased way to evaluate NAF as a source of biomarkers and are sufficiently sensitive for analysis of small NAF volumes (10-50 microl). In this study, we initially evaluated a new process for obtaining NAF and discovered that this process resulted in a volume of NAF that was suitable for analysis in approximately 90% of subjects. Proteomic characterization of NAF identified 64 proteins. Although this list primarily includes abundant and moderately abundant NAF proteins, very few of these proteins have previously been reported in NAF. At least 15 of the NAF proteins identified have previously been reported to be altered in serum or tumor tissue from women with breast cancer, including cathepsin D and osteopontin. In summary, this study provides the first characterization of the NAF proteome and identifies several candidate proteins for future studies on breast cancer markers in NAF.

Expression and immunogenicity of a tumor-associated antigen, 90K/Mac-2 binding protein, in lung carcinoma

BACKGROUND

The authors attempted to obtain shared proteins among lung carcinoma cells by column chromatographies. A glycoprotein with approximately 500 kDa isolated from QG56 cells showed an identical amino acid sequence to 90K/Mac-2 binding protein (M2BP). This protein has been reported to be highly expressed and to modulate the expression of surface molecules involved in immune responses on cultured cancer cells. Therefore, it would be beneficial for M2BP to be targeted in cancer immunotherapy.

METHODS

The authors analyzed the expression of M2BP in lung carcinoma cells and M2BP's immunogenicity as a tumor antigen. Eight cultured lung carcinoma cell lines and 28 tumor tissues from patients with lung carcinoma were examined for the expression of M2BP mRNA and protein. Sera from cancer patients (n = 23) and healthy donors (n = 19) were studied for their reactivity to M2BP peptides by enzyme-linked immunosorbent assay.

RESULTS

Seven of the 8 (87.5%) lung carcinoma cell lines and 17 of the 28 (60.7%) tumor tissues expressed high levels of M2BP mRNA. Most of the M2BP mRNA-positive cancer cell lines and tumors also showed M2BP protein expression. The serum levels of antibodies to M2BP were elevated in 30.4% of the patients. In addition, M2BP-specific immunoglobulin G was observed in all patients with anti-M2BP antibodies.

CONCLUSIONS

M2BP is highly expressed in lung carcinoma cells and is sufficiently immunogenic to elicit specific immunity to this molecule in patients with lung carcinoma. M2BP is expected to be useful as a tumor marker and a target antigen in cancer immunotherapy.

Functional studies on recombinant domains of Mac-2-binding protein

Mac-2-binding protein (M2BP) is a secreted glycoprotein suggested to have a role in host defense. It forms linear and ring-shaped oligomers, with each ring segment being composed of two monomers. We have produced recombinant human M2BP fragments comprising domains 1 and 2 (M2BP-1,2) and domains 3 and 4 (M2BP-3,4) in 293 human kidney cells to characterize structural and functional properties of M2BP. Both fragments were obtained in a native and glycosylated form, as analyzed by CD spectroscopy, trypsin susceptibility, and enzymatic deglycosylation. These results strongly suggest that both fragments are autonomous folding units. All three potential N-glycosylation sites in M2BP-1,2 and all four in M2BP-3,4 were found to be occupied. M2BP-1,2 expressed in tunicamycin-treated cells contained no glycosyl residues, indicating that O-glycosylation is not occurring. Ultracentrifugation revealed that M2BP-1,2 is homogeneously dimeric in the nanomolar range reflecting the properties of intact M2BP. Domain 2 (BTB/POZ domain) is thus identified as the dimerization domain of M2BP, because it has been formerly shown that recombinant domain 1 is monomeric. M2BP-3,4 showed a concentration-dependent self-association, and aggregates of different size and shape were shown by electron microscopy. In contrast to this irregular aggregation of M2BP-3,4, it has been formerly shown that a fragment comprising domains 2-4 still has the ability to form ring-like structures, although the rings are protein-filled, and thus domain 2 appears to be indispensable for ring formation. Solid phase assays showed that M2BP-3,4 contains binding sites for galectin-3, nidogen, and collagens V and VI, whereas M2BP-1,2 is inactive in binding. Both fragments showed no cell adhesive activity in contrast to native M2BP, suggesting that a concerted binding action and/or multivalent interactions of rings are necessary for cell attachment.

Variations in serum IL-7 and 90K/Mac-2 binding protein (Mac-2 BP) levels analysed in cohorts of HIV-1 patients and correlated with clinical changes following antiretroviral therapy

Serum levels of interleukin-7 (IL-7), a non-redundant cytokine that plays a crucial role in lymphopoiesis, are known to be elevated in HIV-1-infected subjects. To examine further the association between levels of IL-7, CD4+ cell counts and viraemia, we analysed these parameters in a large cohort of HIV-1 patients along with serum levels of 90K, a marker of disease severity but with no established involvement in lymphopoiesis. While IL-7 levels were only found to correlate with CD4+ cell counts, 90K levels presented strong correlations with both CD4+ cell numbers and with plasma viral loads (VLs). These correlations were maintained in patients naive to treatment with antiretrovirals (n = 38) but were abolished when the analysis was restricted to the group receiving highly active antiretroviral therapy (HAART, n = 82). Moreover, although 90K levels were significantly reduced in patients on HAART, IL-7 levels continued to be elevated despite successful treatment. The influence of HAART on the variations in these serum parameters was further assessed in a longitudinal study on 32 subjects. The HAART-induced decrease in VLs and increase in CD4+ counts were found to correlate with a reduced serum level of 90K and IL-7, respectively. Nevertheless, following a median period of 33 months of immunological and virological successful HAART, serum levels of IL-7 continued to be significantly elevated compared with those detected in healthy controls. These findings suggest that immunotherapy with IL-7, aimed to replenish T-cell stock in HAART-treated subjects, may have a limited impact on the process of immune reconstitution.

Serum 90K/MAC-2BP glycoprotein in patients with liver cirrhosis and hepatocellular carcinoma: a comparison with alpha-fetoprotein

Glycoprotein 90K/MAC-2BP is a member of the scavenger receptor cystein-rich protein superfamily, which is thought to be involved in immune surveillance, defending the body against pathogens and cancer. 90K serum levels are elevated in patients with cancer of various origins and in viral infections, such as human immunodeficiency virus and hepatitis C virus (HCV). Because in patients with HCV-related cirrhosis the incidence of hepatocellular carcinoma (HCC) is high, in the present paper we examined, by means of an enzyme-linked immunosorbent assay, the 90K serum levels in 103 patients with liver cirrhosis, and in 69 with HCC, and compared them to alpha-fetoprotein, the reference tumor marker for this neoplasm. Serum levels of 90K (cut-off 14 microg/ml) were elevated both in cirrhosis (39%) and HCC (46%) compared to controls (14.1 microg/ml vs. 10.6 microg/ml in cirrhosis, and 14.8 microg/ml vs. 9.1 microg/ml in HCC, p < or = 0.001). There was a significant association with the presence of anti-HCV antibodies. 90K was found to be a non-specific tumor marker which is complementary to alpha-fetoprotein on the basis of its probable different biological significance. In fact, 74% of HCC patients had at least one positive marker. Combined use of 90K and alpha-fetoprotein could improve the sensitivity of a single test in the diagnosis of HCC.

Serum protein 90K/Mac-2BP is an independent predictor of disease severity during hepatitis C virus infection

The serum protein designated 90K/Mac-2BP has been found at elevated concentrations in the sera of patients with various types of cancer and viral infections. The importance of the 90K/Mac-2BP serum concentrations in predicting the response towards interferon-alpha treatment for hepatitis C virus (HCV) infection prompted us to utilize a new ELISA for soluble human 90K/Mac-2BP to monitor the serum concentrations of this protein in our HCV-positive patients. Seventy HCV-PCR and anti-HCV antibody positive patients were analyzed for their serum levels of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, cholinesterase, HCV-viral load, viral subtypes, and 90K/Mac-2BP. On correlation of age and 90K/Mac-2BP levels, we found an apparent correlation that was proved rather to be a strong dependence of 90K/Mac-2BP concentrations on disease severity/duration, which increases with age. Multiple correlation analysis demonstrated the independent nature of 90K/Mac-2BP concentrations, underscoring the potential high utility of this new marker. Our data corroborate the potential of the scavenger receptor family protein 90K/Mac-2BP as an independent predictor of disease severity during HCV infection.

Cyclophilin C-associated protein: a normal secreted glycoprotein that down-modulates endotoxin and proinflammatory responses in vivo

Mouse cyclophilin C-associated protein (CyCAP) is a member of the scavenger-receptor cysteine-rich domain superfamily and is 69% identical to the human Mac-2 binding protein. Here, we show that CyCAP is a widely expressed secreted glycoprotein that modulates the host response to endotoxin. Gene-targeted CyCAP-deficient mice are more sensitive to the lethal effects of endotoxin. In response to endotoxin, CyCAP-deficient mice overproduced interleukin 12 and interferon-gamma systemically and tumor necrosis factor alpha locally; these are proinflammatory molecules that also promote T helper 1 responses. Furthermore, macrophages stimulated in vitro with endotoxin in serum deficient in CyCAP secreted more tumor necrosis factor alpha, supporting the proposal that CyCAP specifically down-modulates endotoxin signaling.

Elevated levels of circulating immunostimulatory 90K in Henoch-Schoenlein purpura

In order to clarify the immunologic reaction present in Henoch-Schoenlein purpura (HSP), 20 children (11 boys and 9 girls; median age, 5.8 +/- 2.8 years) with HSP and 20 sex- and age-matched healthy children were studied. The 90K/Mac-2 BP serum concentrations were significantly higher in the patients than in the healthy controls (12.5 +/- 7.5 vs 4.5 +/- 2.7 micrograms/ml, respectively; P < 0.0001). 90K/Mac-2 BP values higher than the cutoff value were observed in 13 of 20 (65%) patient. The soluble intercellular adhesion molecule 1 concentrations were significantly higher in HSP patients than controls (P < 0.0001), with mean values of 1631 +/- 703 and 85 +/- 16 ng/ml, respectively. The 90K/Mac-2 BP serum levels were significantly correlated with soluble intercellular adhesion molecule 1 (r = 0.90, P < 0.0001). Although the underlying causes of these immunological abnormalities are unclear, these observations suggest that the 90K/Mac-2 BP protein may play a role in the immunological reactions involved in the development of HSP.

Human milk 90K (Mac-2 BP): possible protective effects against acute respiratory infections

Eighty-six children fed human milk were followed prospectively from birth to 12 months of age to assess the effect of milk 90K, a secreted glycoprotein with immune-stimulatory properties, on development of acute respiratory infections (ARI). The level of human milk 90K was inversely related to episodes of ARI (r = - 0.34; P = 0.001). The average 90K level in human milk fed to children who did not develop ARI was significantly higher than in milk fed to children in whom infection occurred on multiple occasions (156.6 +/- 144.8 microg/ml versus 70.9 +/- 92.3 microg/ml; P = 0.001). These data suggest that the protective effects of human milk against ARI may be due in part to immune maturation effects by secreted 90K.

Differential effect on TCR:CD3 stimulation of a 90-kD glycoprotein (gp90/Mac-2BP), a member of the scavenger receptor cysteine-rich domain protein family

We studied the effects of a 90-kD glycoprotein (gp90/Mac-2BP) belonging to the scavenger receptor family, present in normal serum and at increased levels in inflammatory disease and cancer patients, on some T cell function parameters. Whereas the lymphocyte proliferative response to non-specific mitogens such as phytohaemagglutinin (PHA) and concanavalin A (Con A), but not pokeweed mitogen (PWM), was strongly reduced, probably due to the lectin-binding properties of gp90/Mac-2BP, the response to T cell receptor (TCR) agonists such as superantigens and allogeneic cells was potentiated. When lymphocytes were stimulated with different anti-TCR:CD3 MoAbs, both in soluble and solid-phase form, gp90/Mac-2BP was able to down-regulate the proliferative response to anti-CD3 MoAb, whereas the response to anti-TCR alphabeta MoAb was enhanced. A similar differential effect was observed when a MoAb against CD5 (another member of the scavenger receptor superfamily) was added to anti-CD3 or anti-TCR-stimulated cells; anti-CD5 MoAb strongly down-modulated the CD3-mediated response, whereas its presence in culture was associated with potentiation of the response to TCR alphabeta agonists. gp90/Mac-2BP was able per se to up-regulate Ca2+ levels in freshly isolated lymphocytes; moreover, its presence in culture was associated with increased Ca2+ mobilization following stimulation with anti-TCR alphabeta, but not anti-CD3 MoAb. These data indicate that gp90/Mac-2BP could be able to influence some immune responses, possibly through multiple homologous interactions with other members of the scavenger receptor family; moreover, our findings suggest that signalling through the different components of the TCR:CD3 complex may follow distinct activation pathways into the cells.

90K (MAC-2 BP) gene expression in breast cancer and evidence for the production of 90K by peripheral-blood mononuclear cells

The tumor-derived antigen 90K (Mac-2 BP) is a widely expressed, secreted glycoprotein found in the serum of healthy individuals and at elevated levels in the serum of patients with breast cancer and other types of cancer. The precise function of 90K, particularly in the context of tumor-host relationships, has not yet been established. In this study, the clinical significance of 90K mRNA expression was studied in relation to other established prognostic parameters in 86 patients with primary breast carcinoma. The 2.2-kb 90K message was detected in all tumor samples, but there was marked variation in expression levels from tumor to tumor. Patients were classified into 2 groups on the basis of 90K expression: group 1 (n = 62) included patients with low expression, and group 2 (n = 24) consisted of patients with high expression. An inverse significant correlation was found between the levels of 90K mRNA expression and overexpression of c-erbB2/Neu receptor kinase, a marker of poor prognosis for patients with breast cancer. There was no significant difference between the groups with respect to tumor size, number of involved axillary lymph nodes, hormone-receptor status, p53 expression or proliferation activity as estimated by Ki-67 count. Similarly, no association was found between the level of 90K expression and the risk of death from breast cancer. These data are at variance with published findings showing that high serum 90K levels are associated with poor survival. Significantly, investigation of 90K-gene expression in peripheral-blood mononuclear cells (PBMC) revealed higher levels of 90K message in PBMC of breast-cancer patients than in healthy individuals. This new finding suggests that PBMC activated in response to tumor growth and progression may be an important source of serum 90K in breast cancer.

Identification of the tumor antigen 90K domains recognized by monoclonal antibodies SP2 and L3 and preparation and characterization of novel anti-90K monoclonal antibodies

The tumor antigen 90K (Mac-2BP, L3 antigen), which has been shown to have T cell costimulatory activity, is a approximately 90 kDa secreted protein found in high levels in plasma, saliva, breast milk and other human fluids. The 90K antigen can be divided into three domains: an amino terminal scavenger receptor cysteine-rich (SRCR)-like domain (D1), followed by a heavily glycosylated mucin-like domain (D2) and a approximately 27 kDa carboxy-terminal domain (D3). In this study we report on the construction of six different 90K immunoglobulin (Ig) fusion proteins containing different 90K domain combinations. Initially these fusion proteins were used to identify which 90K domain contains the epitopes recognized by the anti-90K monoclonal antibodies (mAb) SP2 and L3. Both of these mAbs were found to recognize 90K-D2. A new panel of anti-90K mAb was then generated by immunizing mice with ascites derived 90K protein. The 90K domain specific fusion proteins were then used to identify novel anti-90K mAbs which recognize the amino terminal SRCR domain and the carboxy terminal approximately 27 kDa domain of 90K. Two novel anti-90K SRCR (D1) and one anti-90 27 kDa domain (D3) mAbs were obtained. These 90K-Ig fusion proteins, as well as the novel and existing anti-90K mAbs, provide a set of tools which will allow further dissection of the structure and function of this immune modulatory protein.

Tumor-associated antigen 90K activates myelomonocytic cell line THP-1

90K is a tumor-associated antigen. Using myelomonocytic cell line THP-1 we determined neopterin production and tryptophan degradation after exposure of cells to 90K in the presence and the absence of interferon-gamma. Interferon-gamma is a well known stimulus for THP-1 cells inducing e.g. neopterin production and tryptophan degradation. Treatment of cells with 50 micrograms/ml 90K induced significant neopterin formation, and the exposure of cells to 90K in addition to 100 U/ml interferon-gamma amplified neopterin production compared to the sole effect of interferon-gamma. In parallel, a significant degradation of tryptophan was observed in culture supernatants leading to the formation of kynurenine. When the cells were treated with the combination of 90K and interferon-gamma the degradation of tryptophan was further enhanced. The data demonstrate that tumor-associated antigen 90K interferes with immunocompetent target cells and is able to induce a biochemical response in monocytic cells.

Circulating immunostimulatory protein 90K and soluble interleukin-2-receptor in human ovarian cancer

The tumor-associated antigen 90K is thought to play an important role in cellular immune defense against malignant cells. It is therefore of interest to investigate whether circulating 90K could be used as a prognostic variable in ovarian cancer, and whether this immunostimulatory antigen is related to other parameters known to be involved in the cellular immune response. In the present retrospective study, circulating levels of antigen 90K were measured before primary surgery in 152 ovarian-cancer patients. A very close association between antigen 90K and s-IL-2R concentrations was pointed out in a stepwise logistic regression model. Univariate analysis of overall survival revealed that antigen 90K and s-IL-2R were associated with poor prognosis. In the multivariate Cox regression, however, neither antigen 90K nor s-IL-2R retained independent prognostic significance. Urinary neopterin was shown to be the only independent prognostic variable among the "immunological parameters" investigated. Additionally, residual disease after primary tumor debulking and histopathologic tumor grade were the most prominent clinico-pathologic parameters for the independent prediction of poor clinical outcome in ovarian-cancer patients.

Expression of tumor-associated 90K-antigen in human breast cancer: no correlation with prognosis and response to first-line therapy with tamoxifen

It has been shown that a 90-kDa protein (90K), with an as yet unknown function, is expressed in the majority of human breast-cancer tissues. In addition, the serum level of this 90K antigen is elevated in a certain proportion of breast-cancer patients, and high serum levels are associated with a poor overall survival. It was therefore of interest to determine whether levels of 90K in tumor tissues could be used as a prognostic variable in breast cancer. In the present study, the levels of 90K in primary breast tumor cytosols were studied with respect to the length of relapse-free or overall survival in 547 patients (median follow-up, 81.4 months), and the relationship with response to first-line tamoxifen therapy and the length of progression-free survival in 184 patients with recurrent disease (median follow-up, 59.8 months). 90K levels in tumor cytosols were determined with an immunoradiometric assay. The cytosolic contents of 90K were not significantly correlated with age, menopausal status, tumor size, nodal status or differentiation grade. On the other hand, the levels of 90K were positively correlated with those of cytosolic estrogen receptor, progesterone receptor, urokinase-type plasminogen activator, its inhibitor PAI-I, cathepsin D and PS2. The cytosolic tumor level of 90K was not associated with the rate of relapse or death in primary breast cancer, nor with response to first-line therapy with tamoxifen or the length of progression-free survival in recurrent disease.

Effects of type-I and -II interferons on 90K antigen expression in ovarian carcinoma cells

Antigen 90K is produced by several tumor-cell lines and by patients with cancer. Its function has not yet been clarified, although recent reports suggest that it plays a role in the tumor-host relationship--for example by stimulation of natural killer and lymphokine-activated killer-cell activity. Previous studies have indicated that 90K expression may be under the influence of interferon-alpha. Here, we provide evidence that both interferon-alpha and -gamma can enhance the secretion of 90K and augment the level of specific mRNA expression in 3 ovarian carcinoma cell lines (OVCAR-3, HTB-77 and SKOV-6). However, interferon-gamma leads to depletion of cellular 90K whereas interferon-alpha increases both secreted and cellular 90K levels. In equimolar concentrations, Interferon-alpha was always superior to interferon-gamma in augmenting 90K protein or mRNA levels. Combinations of TNF with interferon-gamma were highly synergistic both in reducing cell proliferation and in increasing 90K secretion and mRNA expression. This synergism was seen to a lesser extent with interferon-alpha.

Relationship between the tumour-associated antigen 90K and cytokines in the circulation of persons infected with human immunodeficiency virus

A tumour-associated antigen known as 90K has been found in high concentrations in the serum of patients infected with human immunodeficiency virus (HIV) even in the absence of neoplastic complications. In order to investigate the relationship between the production of 90K and soluble inflammatory mediators, we studied serum concentrations of the antigen, tumour necrosis factor-alpha (TNF-alpha), interleukin-I-alpha (IL-I-alpha), interferon-gamma (IFN-gamma), IFN-alpha, neopterin and beta 2-microglobulin (beta 2-m) in patients with non-neoplastic HIV infection at various stages of disease and in control persons. The antigen was detected in all those studied but its concentration was higher in HIV-infected patients compared with controls (P < 0.001), increasing progressively with advancing stages of disease. There was a negative correlation between concentrations of 90K and IL-I-alpha in patients in U.S.A. Centers for Disease Control groups II and III (P < 0.02) and also between that of 90K and both TNF-alpha (P < 0.01) and IL-I-alpha (P < 0.05) in control persons. The results indicate that 90K is not merely a tumour-associated antigen and that its production may be part of immune and inflammatory responses in the absence of neoplasia. The correlation between the concentrations of 90K and of some cytokines in asymptomatic patients and healthy persons suggests that 90K may be part of a network of immune and inflammatory reactants.

Prognostic value of a novel circulating serum 90K antigen in breast cancer

Monoclonal antibody SP-2 to the tumour-associated antigen 90K was generated by immunisation with conditioned medium of human breast cancer cells. We investigated whether circulating levels of 90K can influence the prognosis of patients with breast cancer. Serum samples were obtained from 425 patients with histologically proven breast cancer with no clinical evidence of disease after surgery (NED) and in 310 patients with metastatic disease. Serum 90K was determined by a new immunoradiometric assay (IRMA). Antigen levels in NED patients were elevated in 18.5% of cases, mean levels being higher than in healthy controls (P = 0.001). Among 375 evaluable patients, the 75-month overall survival for 90K-negative (< or = 11 U ml-1) and 90K-positive (> 11 U ml-1) patients was 78% and 53% respectively (P = 0.004). The prognostic value of 90K appeared to be limited to patients with node-positive disease. Number of metastatic axillary lymph nodes and level of 90K antigen were the only independent variables for predicting overall survival. Patients with metastatic breast cancer had elevated 90K in 51.3% of cases. High 90K levels were significantly associated with the presence of metastases to liver, shorter disease-free interval and younger age. We conclude that an elevated 90K antigen level in serum is a predictor of poor prognosis in breast cancer.

Purification and characterization of a 90 kDa protein released from human tumors and tumor cell lines

A novel tumor-associated protein, termed 90K, and recognized by mAb SP-2 was purified from serum of breast cancer patients, ovarian cancer ascitic fluid and conditioned medium of human breast cancer cells. In these three sources, native 90K is present as a high molecular weight complex that was dissociated by SDS-PAGE into a major band of approximately 90,000 Da. On the basis of electrophoretic mobility, buoyant density value, amino acid composition, and immunoreactivity, the 90K from the different sources appeared to be identical. NH2-terminal amino acid sequence revealed no homology to known protein.

Dynamic test with recombinant interferon-alpha-2b: effect on 90K and other tumour-associated antigens in cancer patients without evidence of disease

We have previously shown that a short course of recombinant interferon-alpha-2b (rIFN-alpha-2b) (3 million units day for 5 days) for patients with primary gynaecologic malignancies was able to increase the circulating levels of a newly discovered tumour associated antigen, termed 90K. In this study, we have investigated the effects of the same modality of administration of rIFN-alpha-2b in 62 patients with breast and colorectal cancer whose primary tumour was surgically removed 1 month before and who were without evidence of disease (NED) at the time of the study. A significant increase of 90K serum concentration was already observed 24 h after the first r-IFN-alpha-2b injection and persisted throughout the investigational period. The increase was more pronounced in patients with a basal 90K-negative than a 90K-positive assay. Of 54 patients who started the test with a 90K negative assay, 17 (31%) shifted to a positive assay after rIFN-alpha-2b. Twenty-eight of 62 (45%) patients exhibited a 90K value above the mean increment of the whole population. The serum levels of CEA, CA-15-3, CA 19-9, and alpha-fetoprotein measured in the same serum samples were not modified. After 2 years of follow-up, ten patients relapsed. Six of them showed a 90K increase above the mean increment of the whole population. As with ovarian cancer, the increase of 90K following r-IFN-alpha-2b administration might be of importance for the early detection of disease recurrence in clinically NED breast and colon cancer patients.

Recombinant alpha-2b-interferon dynamic test as a potential tool in predicting disease status during second look in ovarian cancer. A preliminary report

The circulating levels of a 90-kilodalton (KD) tumor-associated antigen were measured in the blood of 26 patients with ovarian cancer in clinical remission who received a short course of recombinant alpha-2b-interferon (rIFN-alpha-2b, 3 million U/m2/d intramuscularly for 3 days) before second-look procedures. The administration of rIFN-alpha-2b to 90-KD antigen-positive patients produced a slight increase of the marker. However, in patients without the marker but with evidence of disease, a remarkable increase above the cutoff level was observed. Less pronounced modifications of 90-KD antigen serum levels were found in patients with no disease at second look. Moreover, considering the 90-KD antigen mean percentage increase, the dynamic test with rIFN-alpha-2b was able to eliminate five of six false-negative results obtained with the 90-KD antigen basal assay alone. The sensitivity of the assay increased to 92% after IFN compared with 54% for the 90-KD antigen assay alone. An increase (greater than 100% above pretreatment titer) of 90-KD antigen levels during the test also was observed in four patients with no evidence of disease at second look. In two of these false-positive cases, recurrence of disease was observed 13 and 24 months later. At the time of this analysis, none of the patients with a negative second look and negative dynamic test had relapsed. These results suggest that the dynamic test with rIFN-alpha-2b might be a new tool to assess disease status in patients with ovarian cancer before second-look procedures.

Recombinant alpha-2b-interferon enhances the circulating levels of a 90-kilodalton (K) tumor-associated antigen in patients with gynecologic and breast malignancies

The circulating levels of a 90-kilodalton (K) tumor-associated antigen were measured in the blood of 43 patients with gynecologic and breast malignancies who underwent a short course of recombinant alpha-2b-interferon (rIFN alpha-2b) (3 million U/m2/d intramuscularly [IM] for 3 days). Of the 43 patients, 23 showed abnormal 90-K levels (greater than 1.7 U/ml). A significant increase of antigen levels was already observed 24 hours after the first administration and persisted throughout the investigation period. Of 20 patients with 90-K levels below the normal limit, 12 went over the normal cutoff value after two rIFN alpha-2b injections. No significant modifications of 90-K levels were detected in nine women receiving rIFN alpha-2b for the treatment of genital condylomata. The serum levels of two other tumor-associated antigens, CA 125 and CA 15-3, were not modified by rIFN alpha-2b administration. The ability of rIFN alpha-2b to increase the circulating levels of 90-K might have important clinical implications for the serodetection of cancer.

Predictive value of multiple tumor marker assays in second-look procedures for ovarian cancer

Sera from 51 ovarian cancer patients in clinical remission undergoing a second-look operation were studied. CA 125, CA 15-3, and 90K assays were performed in the week preceding surgery. Twenty-seven patients (53%) had no evidence of disease; 3 (6%) and 21 (41%) had microscopic and macroscopic disease. All patients but two with no evidence of disease had normal CA 125 serum levels, as did the three cases with microscopic disease and 6 patients with macroscopically detectable tumor. Of 17 patients with high CA 125 values, 15 (88%) were found to have persistent disease. Hence, the sensitivity and specificity of a CA 125 assay were 62 and 93%, respectively. CA 15-3 levels were low in all patients with no evidence of disease, in 2 cases with microscopic disease, and in 2 cases with residual tumor greater than 1 cm. All patients with high CA 15-3 titers had a positive second-look. The sensitivity and specificity of assay were 69 and 100%, respectively. With the 90K assay, 4 false-positive and 4 false-negative results were found and the sensitivity and specificity were 69 and 67%, respectively. However, 3 of 4 cases with a false-positive 90K assay had recurrence of disease with 7, 9, and 20 months later. Combination of the three markers increased sensitivity to 79%. These data suggest that more effective surveillance of disease status at second-look is obtained by using a combination of tumor marker assays.

Circulating tumor marker levels in advanced breast carcinoma correlate with the extent of metastatic disease

The importance of the extent of metastatic disease in the circulating levels of CA 15-3 and carcinoembryonic antigens (CEA) was studied in 173 patients with advanced breast carcinoma. Estimates of the extent of metastatic disease were obtained by an objective arbitrary scale. Patients were observed clinically after serum samples were obtained, and survival was recorded. Elevated values of CA 15-3 (greater than 40 U/ml) were seen in 130 patients and CEA values (greater than 5 ng/ml) in 97 cases (75% versus 56%, P less than .0001). Elevated CA 15-3 values correlated with the estimated extent of metastatic disease (P less than .0001), number of metastases (P = .0006), and survival from study entry (P = .01). Elevated CEA values correlated with extent of disease (P less than .0001), but not with the number of metastases or with survival. No correlation was found between the elevated values of CA 15-3 or CEA and age, menopausal status, and initial tumor size or nodal status. The combination of the elevated values of CA 15-3 and CEA was more sensitive than CA 15-3 alone (P = .04), but there were no significant improvements when subgroups were considered. Significant differences, that depended on which specific organ was affected dominantly by metastases, were seen in the mean levels of CA 15-3 antigen. Similarly, patients with liver involvement had higher mean levels of CA 15-3 than those without hepatic metastases. A stepwise regression analysis of the dominant site of metastases, liver involvement, and estimated extent of disease showed that only the latter parameter retained a significant correlation with CA 15-3 antigen levels (P less than .0001). Median survival of patients who showed abnormal CA 15-3 levels was significantly shorter than that of patients with nonelevated CA 15-3 (10.1 versus 18.0 months, P = .04). This difference was not appreciated with CEA levels (10.2 versus 12.2 months, P = .4). We conclude that tumor marker levels in patients with advanced breast carcinoma correlate with the extent of metastatic disease. In addition, the CA 15-3 assay is more sensitive and correlates more accurately with the extent of disease than CEA. Finally, the observed CA 15-3 differences by organ involvement are related to the extent of disease variations. The objective evaluation of the extent of metastatic disease provides a new approach in the study and comparison of breast cancer-associated tumor markers.