The radioimmunoassay of circulating carcinoembryonic antigen of the human digestive system

Unusual elevation of CEA in a patient with history of colon cancer

A 35-year-old female received right hemicolectomy for a poorly differentiated adenocarcinoma of the ascending colon with lymph node metastasis (1/28) in February 1997. CEA was 1.68 ng/microl prior to colectomy. Adjuvant chemotherapy with weekly 5-FU and leucovorin intravenously was started following surgery and discontinued after 17 doses in May 1997. She received bilateral salpingo-ophorecctomy for metastatic cancer in August 1999. Intravenous chemotherapy was resumed with weekly 5-FU and leucovorin intravenously in August 1999. CEA was 93.8 ng/microl in November 1999. Intravenous chemotherapy was discontinued after 20 doses and oral chemotherapy with futraful and leucovorin was started in January 2000. CEA was found to be 240.3 ng/microl in December 1999 and then elevated to 1521.3 ng/microl in June 2001, which was 10 months after resection of metastatic ovarian cancer. No metastatic lesions could be detected, however, with image studies. The CEA decreased to 396.6 ng/microl three months later. Futraful was switched to uracil-tegafur (UFUR) in September 2001. The CEA for the patient ranged from 68.5 to 298.9 ng/microl for the following 5 years without aggressive chemotherapy. No evidence of recurrence could be demonstrated by imaging studies. The patient is not a smoker and denied exposure to a smoking environment. She was also not known to have persistent infections, inflammatory bowel disease, pancreatitis, cirrhosis of the liver, or any benign tumors. The current case suggested that: (i) elevation of CEA is not necessarily well correlated with presence of metastatic colon cancer; (ii) some patients may live with elevated CEA for years without evidence of recurrence or metastasis; (iii) aggressive chemotherapy may not be necessary in patients with only elevated CEA.

Identification of PSME3 as a novel serum tumor marker for colorectal cancer by combining two-dimensional polyacrylamide gel electrophoresis with a strictly mass spectrometry-based approach for data analysis

The purpose of this study was to identify and validate novel serological protein biomarkers of human colorectal cancer (CRC). Proteins from matched CRC and adjacent normal tissue samples were resolved by two-dimensional gel electrophoresis. From each gel all spots were excised, and enveloped proteins were identified by MS. By comparison of the resulting protein profiles, dysregulated proteins can be identified. A list of all identified proteins and validation of five exemplarily selected proteins, elevated in CRC was reported previously (Roessler, M., Rollinger, W., Palme, S., Hagmann, M. L., Berndt, P., Engel, A. M., Schneidinger, B., Pfeffer, M., Andres, H., Karl, J., Bodenmuller, H., Ruschoff, J., Henkel, T., Rohr, G., Rossol, S., Rosch, W., Langen, H., Zolg, W., and Tacke, M. (2005) Identification of nicotinamide N-methyltransferase as a novel serum tumor marker for colorectal cancer. Clin. Cancer Res. 11, 6550-6557). Here we describe identification and initial validation of another potential marker protein for CRC. Comparison of tissue protein profiles revealed strong elevation of proteasome activator complex subunit 3 (PSME3) expression in CRC tissue. This dysregulation was not detectable based on the spot pattern. The PSME3-containing spot on tumor gels showed no visible difference to the corresponding spot on matched control gels. MS analysis revealed the presence of two proteins, PSME3 and annexin 4 (ANXA4) in one and the same spot on tumor gels, whereas the matched spot contained only one protein, ANXA4, on control gels. Therefore, dysregulation of PSME3 was masked by ANXA4 and could only be recognized by MS-based analysis but not by image analysis. To validate this finding, antibody to PSME3 was developed, and up-regulation in CRC was confirmed by Western blot analysis and immunohistochemistry. Finally by developing a highly sensitive immunoassay, PSME3 could be detected in human sera and was significantly elevated in CRC patients compared with healthy donors and patients with benign bowel disease. We propose that PSME3 be considered a novel serum tumor marker for CRC that may have significance in the detection and in the management of patients with this disease. Further studies are needed to fully assess the potential clinical value of this marker candidate.

Differential gene expression profile reveals deregulation of pregnancy specific beta1 glycoprotein 9 early during colorectal carcinogenesis

Background

APC (Adenomatous polyposis coli) plays an important role in the pathogenesis of both familial and sporadic colorectal cancer. Patients carrying germline APC mutations develop multiple colonic adenomas at younger age and higher frequency than non-carrier cases which indicates that silencing of one APC allele may be sufficient to initiate the transformation process.

Methods

To elucidate the biological dysregulation underlying adenoma formation we examined global gene expression profiles of adenomas and corresponding normal mucosa from an FAP patient. Differential expression of the most significant gene identified in this study was further validated by mRNA in situ hybridization, reverse transcriptase PCR and Northern blotting in different sets of adenomas, tumours and cancer cell lines.

Results

Eighty four genes were differentially expressed between all adenomas and corresponding normal mucosa, while only seven genes showed differential expression within the adenomas. The first group included pregnancy specific β-1 glycoprotein 9 (PSG9) (p < 0.006). PSG9 is a member of the carcinoembryonic antigen (CEA)/PSG family and is produced at high levels during pregnancy, mainly by syncytiotrophoblasts. Further analysis of sporadic and familial colorectal cancer confirmed that PSG9 is ectopically upregulated in vivo by cancer cells. In total, deregulation of PSG9 mRNA was detected in 78% (14/18) of FAP adenomas and 75% (45/60) of sporadic colorectal cancer cases tested.

Conclusion

Detection of PSG9 expression in adenomas, and at higher levels in FAP cases, indicates that germline APC mutations and defects in Wnt signalling modulate PSG9 expression. Since PSG9 is not found in the non-pregnant adult except in association with cancer, and it appears to be an early molecular event associated with colorectal cancer monitoring of its expression may be useful as a biomarker for the early detection of this disease.

Noninvasive testing for colorectal cancer: a review

OBJECTIVES

Colorectal cancer (CRC) is the second leading cause of cancer-related death in the United States. Endoscopic screening is now in favor and its use is increasing, but overall participation rates are poor. A substantial percentage of the population will likely continue to resist endoscopic screening. As such, a noninvasive biomarker for the early detection of CRC remains a priority. Herein, we (i) review the currently available noninvasive screening markers for the early detection of CRC, (ii) discuss newer markers that have undergone preliminary testing, and (iii) introduce and explain potentially promising markers of the future.

METHODS

The published literature on markers for early detection of CRC was identified using a MEDLINE/PubMed search with secondary review of cited publications.

RESULTS

Noninvasive testing for CRC is most advanced in testing for stool fecal occult blood, globin, or DNA mutations. Study of abnormal mucins has also been explored. Research for serum-based markers is just beginning and includes serum proteomics, nuclear matrix proteins, and serum DNA testing.

CONCLUSIONS

Serial guaiac-based fecal occult blood testing (FOBT) is simple, inexpensive, and proven effective at reducing mortality from CRC. Immunochemical fecal occult blood tests facilitate compliance and offer improved specificity, but at increased cost in comparison to FOBT. Fecal DNA testing may provide enhanced sensitivity for detection of CRC in comparison with FOBT, but its high cost limits its use for generalized screening. Rectal mucin testing requires additional evaluation to determine its sensitivity and specificity in comparison with guaiac-based FOBT. Serum tests, such as proteomics, nuclear matrix proteins, and serum DNA, are still in their infancy, but remain a hope for the future.

How to Appraise a Diagnostic Test

Clinicians frequently confront challenges when using diagnostic tests to help them decide whether the patient before them suffers from a particular target condition or diagnosis. The primary issues to consider when determining the validity of a diagnostic test study are how the authors assembled the patients and whether they used an appropriate reference standard in all patients to determine whether the patients did or did not have the target condition. Surgeons should be interested in the characteristics of the test that indicates the direction and magnitude of change in the probability of the target condition associated with a particular test result. The likelihood ratio best captures the link between the pretest probability of the target condition and the probability after the test results are obtained (also called the posttest probability). Many studies, however, present the properties of diagnostic tests in less clinically useful terms: sensitivity and specificity. Sensitivity denotes the proportion of people with the disorder in whom the test result is positive. Specificity denotes the proportion of people without the disorder in whom the test result is negative. Application of the guides presented in this article can allow surgeons to assess critically studies regarding a diagnostic test.

Determining tumor apoptosis and necrosis in patient serum using cytokeratin 18 as a biomarker

Intracellular macromolecules are released from dying tumor cells and may subsequently be detected in patient blood. In this review, we will discuss the use of cytokeratin-18 as a serum biomarker for monitoring therapy-induced cell death. Cytokeratins are abundant intracellular proteins expressed by most types of carcinoma, but not by treatment-sensitive cells from bone marrow and other tissues. Release of cytokeratins into blood is therefore expected to show some specificity for tumor cell death. Cytokeratin-18 (CK18) is cleaved by caspases specifically during apoptosis, and the molecular form of this protein (caspase-cleaved vs. non-cleaved) released from dying tumor cells is therefore diagnostic as to the type of cell death (apoptosis vs. necrosis). Analyses of different CK18 forms in patient sera have suggested that tumor apoptosis may not necessarily be the dominating death mode in many tumors in vivo. Measurements of increased levels of CK18 in serum during therapy of prostate and breast cancer patients have been encouraging with regard to the possible future use of CK18 as a biomarker for monitoring therapy efficiency.

Clinical utility of biochemical markers in colorectal cancer: European Group on Tumour Markers (EGTM) guidelines

In recent years, numerous serum and cell/tissue-based markers have been described for colorectal cancer (CRC). The aim of this article was to provide guidelines for the routine clinical use of some of these markers. Lack of sensitivity and specificity preclude the use of any available serum markers such as carcinoembryonic antigen (CEA), CA 19-9, CA 242, CA 72-4, tissue polypeptide antigen (TPA) or tissue polypeptide-specific antigen (TPS) for the early detection of CRC. However, preoperative measurement of CEA is desirable as this may give independent prognostic information, help with surgical management and provide a baseline level for subsequent determinations. For patients with stage 2 (Dukes' B) and 3 (Dukes' C) disease who may be candidates for liver resection, CEA levels should be measured every 2-3 months for at least 3 years after diagnosis. For monitoring treatment of advanced disease, CEA should also be tested every 2-3 months. Insufficient evidence is presently available to recommend the routine use of other serum markers for monitoring purposes. Similarly, the new cell and tissue-based markers (e.g, ras, P53) cannot yet be recommended for routine clinical use.

Polarized distribution of carcinoembryonic antigen is associated with a tight junction molecule in human colorectal adenocarcinoma

This study we presents a novel anti-occludin monoclonal antibody that can be used for formalin-fixed, paraffin-embedded tissue sections. The relationships between aberrant localization of carcinoembryonic antigen (CEA) and abnormalities of tight junctions were studied in human colorectal cancers by this antibody. Abnormalities in the cell surface expression of CEA have been shown to be characteristic of human colorectal cancer cells. Cancer cells that participated in the formation of glandular structures expressed occludin at the apical cell border and CEA was expressed more apically than occludin. Where cancer cells showed solid nests without glandular structures, occludin was completely lost and CEA was demonstrated in a diffuse pattern throughout the cells. These findings suggest that the polarized apical expression of CEA in neoplastic glandular structures depends on the expression of occludin and the fence function of tight junctions. During tumour progression, loss of occludin may lead to the loss of membrane polarity and the non-polarized expression of CEA. The antibody described provides a powerful tool for the study of tight junctions in surgically resected human tissue.

Preoperative serum levels of CA 72-4, CEA, CA 19-9, and alpha-fetoprotein in patients with gastric cancer

INTRODUCTION

The clinical importance of preoperative serum levels of CA 72-4, carcinoembryonic antigen (CEA), CA 19-9, and alpha-fetoprotein (AFP) was prospectively evaluated in 44 patients with gastric cancer.

METHOD

The serum tumor marker levels were determined by commercial radioimmunoassay kits. Positivity for CA 72-4 (>4 U/mL), CEA (>5 ng/mL), CA 19-9 (>37 U/mL), and AFP (>10 ng/mL) were correlated according to the stage, histology, and lymph node metastasis.

RESULTS AND DISCUSSION

CA 72-4 showed a higher positivity rate for gastric cancer (47.7%) than CEA (25%), CA 19-9 (25%), and AFP (0%). The combination of CA 72-4 with CEA and CA 19-9 increased the sensitivity to 61.4%. The positivity rates of CA 72-4 in patients at stages I and II (initial disease) and in patients at stages III and IV (advanced disease) were 9% and 60.6%, respectively (P < 0.005). No correlation was found between CEA and CA 19-9 levels and the stage of gastric cancer. There was a tendency of positivity for CA 72-4 to suggest lymph node involvement, but it was not significant (P = 0.075). Serum levels of tumor markers did not show a correlation with the histological types of gastric cancer.

CONCLUSION

Preoperative serum levels of CA 72-4 provided a predictive value in indicating advanced gastric cancer.

Tumor-associated antigen expression and growth requirements predict tumorigenesis in squamous cell carcinoma

Squamous cell carcinomas (SCCs) are the most common malignancies in man. While clinical specimens are theoretically ideal to study tumor development and progression, practical difficulties such as normal cell contamination, the presence of different cell types. and limited material make preclinical studies of model systems involving a homogeneous population of normal or transformed cells preferable. Tumor-associated antigens (TAAs) found on the cell surface, including integrins, mucins, cadherins, growth factor receptors, membrane bound antigens, and glycoproteins are known to play an important role in squamous carcinogenesis. We hypothesized that (1) alterations in TAA expression in vitro predict in vivo alterations, (2) analysis of a group of TAAs would provide a better indication of SCC tumorigenesis than any single marker, and (3) SCCs with independence from exogenous growth factors in vitro would demonstrate the most aggressive growth in vivo. The cell line which grew best in vitro without serum or other supplements demonstrated the most rapid tumor growth. whereas cell lines which grew only with supplements rarely formed tumors. Normal keratinocytes. eight SCC and two immortal keratinocyte cell lines were evaluated by flow cytometry for the expression of 10 cell surface markers, including alpha and beta integrins, minor blood group-related carbohydrate determinants. carcinoembryonic antigen-related proteins, E-cadherin, and GA733 (epithelial glycoprotein. epithelial cell adhesion molecule). None of the cell lines with abnormal expression of < or = 2 markers formed tumors, whereas all lines with altered expression of > or = 3 markers formed tumors. Using GA733 expression as an example, we found that altered TAA expression in vitro predicted the presence of TAA alterations in clinical specimens. In summary, in vitro independence from supplements for optimal growth and altered expression of > or = 3 cell surface markers were good predictors of SCC tumorigenesis. These findings may be useful in decreasing the need for whole animal tumorigenicity experiments.

Carcinoembryonic Antigen as a Marker for Colorectal Cancer: Is It Clinically Useful?

Background: Carcinoembryonic antigen (CEA) is one of the most widely used tumor markers worldwide. Its main application is mostly in gastrointestinal cancers, especially in colorectal malignancy. Although in use for almost 30 years, the clinical value of CEA in colorectal cancer is still not clear.

Methods: The literature relevant to the clinical value of CEA in colorectal cancer was reviewed. Particular attention was paid to studies involving metaanalyses and guidelines issued by Expert Panels.

Results: Although of little use in detecting early colorectal cancer, high preoperative concentrations of CEA correlate with adverse prognosis. Serial CEA measurements can detect recurrent colorectal cancer with a sensitivity of ∼80%, a specificity of ∼70%, and can provide a lead time of ∼5 months. CEA is the most frequent indicator of recurrence in asymptomatic patients and currently is the most cost-effective test for the preclinical detection of resectable disease. CEA is most useful for the early detection of liver metastasis in patients with diagnosed colorectal cancer. Overall, however, little evidence is available that monitoring of all patients with diagnosed colorectal cancer leads to enhanced patient outcome or quality of life.

Conclusions: Currently, the most useful application of CEA is in the detection of liver metastasis from colorectal cancers. Because of the relative success of surgery in resecting hepatic metastases, serial determinations of the marker are recommended for detecting cancer spread to the liver. In the future, preoperative concentrations of CEA may be included with the standard staging procedures for assessing prognosis.

Clinical significance of the preoperative plasma carcinoembryonic antigen (CEA) level in patients with carcinoma of the large bowel

Preoperative levels of perchloric acid extractable plasma CEA were measured in 911 patients with complaints of the digestive system. A final diagnosis of benign disease was made for 579 patients; 332 patients were found to have cancer. Data for the preoperative CEA values were examined for clinical significance as an aide to diagnosis, preoperative disease staging, and prognosis. The results of our analysis support the conclusions of many investigators that the CEA assay is not a clinically useful diagnostic test, but it shows limited value in preoperative staging and a somewhat stronger correlation with prognosis.

Biological markers of risk in nipple aspirate fluid are associated with residual cancer and tumour size

We previously demonstrated that nipple aspirate fluid (NAF) can be obtained from virtually all non-Asian women between the ages of 30 and 72. The focus of this report is to (1) determine the association of candidate markers of breast cancer risk in NAF obtained from fresh mastectomy specimens with residual breast carcinoma, and (2) evaluate the association of the markers with breast tumour progression. Nipple aspiration was performed on 97 specimens. Cytology, DNA index (including % hypertetraploid cells), cell cycle parameters (S phase fraction, % cells in G2/M), prostate-specific antigen (PSA), epidermal growth factor (EGF), testosterone, carcinoembryonic antigen (CEA) and prostaglandin D synthase (PGDS) were evaluated in NAF for their association with (1) residual ductal carcinoma in situ (DCIS) or invasive cancer, and (2) pathologic tumour size. NAF was obtained from 99% (96/97) of specimens. Atypical and malignant NAF cytology were significantly associated with residual DCIS or invasive cancer (P = 0.001) and with larger tumours (P = 0.004). One hundred per cent and 88% of subjects with malignant and atypical NAF cytology, respectively, had residual carcinoma. The percentage of cells in G2/M and DNA index were associated both with risk of residual carcinoma (P = 0.01 for each) and larger tumour size (DNA index, P = 0.03; G2/M, P = 0.05), although neither biomarker improved the ability of NAF cytology, to predict residual breast cancer. Higher DNA index was associated with atypical cytology (P = 0.0001). In summary, atypical and malignant NAF cytology are associated with larger tumour size, and are highly predictive of residual carcinoma after needle or excisional biopsy of the breast.

The carcinoembryonic antigen (CEA) family: structures, suggested functions and expression in normal and malignant tissues

The human CEA family has been fully characterized. It comprises 29 genes of which 18 are expressed; 7 belonging to the CEA subgroup and 11 to the pregnancy specific glycoprotein subgroup. CEA is an important tumor marker for colorectal and some other carcinomas. The CEA subgroup members are cell membrane associated and show a complex expression pattern in normal and cancerous tissues with notably CEA showing a selective epithelial expression. Several CEA subgroup members possess cell adhesion properties and the primordial member, biliary glycoprotein, seems to function in signal transduction or regulation of signal transduction possibly in association with other CEA sub-family members. A modified ITAM/ITIM motif is identified in the cytoplasmatic domain of BGP. A role of CEA in innate immunity is envisioned.

Elevated carcinoembryonic antigen levels correlating with disease recurrence in a patient with adenoid cystic carcinoma

BACKGROUND

Carcinoembryonic antigen (CEA) is an oncofetal glycoprotein involved in cell recognition and adhesion. Serum CEA has been extensively studied as a potential chemical marker for malignancy, most notably in patients with colon carcinoma. Serum CEA measurements have not been reported for patients with salivary gland carcinomas.

METHODS

Serum CEA was measured in a case study using enzyme immunoassay with monoclonal antibody specific for CEA. Tissue was examined with standard histologic and immunohistologic methods.

RESULTS

A patient was initially seen with adenoid cystic carcinoma (ACC) of the trachea and had a markedly elevated serum CEA level which declined after surgical resection. The serum CEA level became elevated again when the patient developed abdominal metastases and then declined after debulking of the tumor. Immunohistochemical study of the tumor was positive for CEA.

CONCLUSIONS

The measurement of serum CEA levels may play a role in the management of patients with ACC. Clinical investigation utilizing monoclonal antibodies against CEA, for imaging and for the delivery of chemotherapy and radiotherapy may be worthwhile.

Serological tumor markers for small cell lung cancer and their therapeutic implications

Serological tumor markers may become widely used as inexpensive and non-invasive methods of cancer detection. Markers of current interest for small cell lung cancer (SCLC) comprise enzymes, peptides, proteins, and carbohydrates. None of the serological markers for SCLC have yet proven to be of diagnostic value and at present their use is limited to monitoring disease and indicating prognosis. However, whilst serological markers related to the metabolic state of SCLC cells, such as neuron-specific enolase, serum thymidine kinase and tissue polypeptide antigen, may only be used for monitoring patients and for estimating prognosis, the other serological markers under current investigation may be used to indicate new treatment forms. Several novel approaches, including interference in the autocrine growth-regulating loop of SCLC by either peptides or antibodies, have been tried, SCLC is a highly heterogeneous tumor with respect to antigen expression, regulation of growth, and differentiation state. It is therefore important that new interventions are directed against both antigen-positive and antigen-negative tumor cells. For instance, radioisotopes or enzymes coupled to antibodies may be effective by exerting toxicity at some distance from the target. Antigens expressed on SCLC cells, such as peptide receptors involved in growth regulation, carbohydrate antigens like Lewis antigens, carcinoembryonic antigen and the ganglioside fucosylGM1, provide potential targets for antibody-conjugated therapy.

Carcinoembryonic antigen in anal carcinoma

Patients with squamous cell carcinoma of the anal canal occasionally present with an elevated level of carcinoembryonic antigen (CEA) in serum. The present study was performed to evaluate the clinical importance of this observation. Serum CEA was measured in 106 patients prior to chemo- and radiotherapy and during follow-up. Twenty patients had elevated serum CEA level before treatment. In 6 of 12 cases, serum CEA did not normalize after successful treatment and in 4 of 7 cases it rose no further despite progressive disease. CEA-positive tumours were more often poorly differentiated than CEA-negative tumours. There was no significant correlation between serum CEA, tumour CEA and prognosis. We conclude that measurement of serum CEA and staining of tumour CEA lack clinical importance.

Clinical significance of tumor marker NCC-ST 439 in large bowel cancers

We examined serum NCC-ST 439 for its significance as a tumor marker of large bowel cancer in 121 patients with primary and 36 with recurrent large bowel cancer. Serum NCC-ST 439 was positive in 27.3 percent of the former and 66.7 percent of the latter. It was false-positive in only 5.6 percent of patients with benign diseases. Positive serum NCC-ST 439 correlated with lymph node and liver metastases. The combination assay for NCC-ST 439, CEA, and CA19-9 was positive in 49.6 percent of the patients with primary tumors and 88.9 percent of those with recurrent tumors; in other words, the diagnostic accuracy improved. The results demonstrated that the determination of serum NCC-ST 439 in large bowel cancer might be useful in cancer staging and that NCC-ST 439, if used in combination with CEA, is particularly useful in diagnosing recurrences because of its improved diagnostic accuracy.

Epithelial cyst of the fourth ventricle. Case report

A case of epithelial cyst in the fourth ventricle of a 4-year-old child is described. A single epithelial layer with a clear basement membrane lining the cyst wall was observed. There were no prominent histological findings to suggest a pathogenesis for this cyst based on immunohistochemical or ultrastructural studies; however, the cyst fluid contained significant amounts of carcinoembryonic antigen. It is considered that the epithelial layer lining the cyst wall was possibly of endodermal origin.

CA 72-4 radioimmunoassay in the diagnosis of malignant effusions. Comparison of various tumor markers

We evaluated the utility of the CA 72-4, CEA, CA 125, CA 19-9 and CA 15-3 radioimmunoassays for the detection of tumor-associated antigens (TAAs) in effusions of malignant vs. benign origin. Fluids were obtained from 51 patients with adenocarcinomas, 27 with non-epithelial malignancies, and 68 with benign disorders. The CA 72-4 radioimmunoassay (cut-off value 8.5 U/ml) detected the TAG-72 antigen in 51% of adenocarcinoma patients' effusions, while only 1 of 68 benign specimens had an elevated TAG-72 level. Similarly, CEA levels above 5 ng/ml were found in 55% of the fluids from patients with adenocarcinoma and 3.2% of effusions from patients with benign disease. CA 19-9 (cut-off value 37 U/ml) exhibited a lower degree of sensitivity, with positive values in 23.5% of the effusions due to adenocarcinomas and in 4.5% of the effusions due to benign disease. At a cut-off value of 29 U/ml, CA 15-3 was positive in 49% of fluids from patients with adenocarcinoma and in 3.0% of the benign fluids. The CA 125 RIA failed to show any specificity using the established cut-off value of 35 U/ml, with approximately 80% of all the effusions giving positive results. The specificity of the assay was increased by using a cut-off value of 3000 U/ml, but with a substantial loss in sensitivity (23.5%). Using a combination of the CA 72-4 and CEA RIAs the sensitivity for malignant effusions was increased to 73.5%. No additional improvement in the overall sensitivity was observed when using the CA 72-4 assay in combination with assays for the other markers, except in the case of 1 effusion. We conclude that the CA 72-4 RIA, possibly in combination with other assays such as CEA, may be useful in distinguishing between adenocarcinomatous and benign effusions.

Cloning of the complete gene for carcinoembryonic antigen: analysis of its promoter indicates a region conveying cell type-specific expression

Carcinoembryonic antigen (CEA) is a widely used tumor marker, especially in the surveillance of colonic cancer patients. Although CEA is also present in some normal tissues, it is apparently expressed at higher levels in tumorous tissues than in corresponding normal tissues. As a first step toward analyzing the regulation of expression of CEA at the transcriptional level, we have isolated and characterized a cosmid clone (cosCEA1), which contains the entire coding region of the CEA gene. A close correlation exists between the exon and deduced immunoglobulin-like domain borders. We have determined a cluster of transcriptional starts for CEA and the closely related nonspecific cross-reacting antigen (NCA) gene and have sequenced their putative promoters. Regions of sequence homology are found as far as approximately 500 nucleotides upstream from the translational starts of these genes, but farther upstream they diverge completely. In both cases we were unable to find classic TATA or CAAT boxes at their expected positions. To characterize the CEA and NCA promoters, we carried out transient transfection assays with promoter-indicator gene constructs in the CEA-producing adenocarcinoma cell line SW403, as well as in nonproducing HeLa cells. A CEA gene promoter construct, containing approximately 400 nucleotides upstream from the translational start, showed nine times higher activity in the SW403 than in the HeLa cell line. This indicates that cis-acting sequences which convey cell type-specific expression of the CEA gene are contained within this region.

Cloning of the complete gene for carcinoembryonic antigen: analysis of its promoter indicates a region conveying cell type-specific expression

Carcinoembryonic antigen (CEA) is a widely used tumor marker, especially in the surveillance of colonic cancer patients. Although CEA is also present in some normal tissues, it is apparently expressed at higher levels in tumorous tissues than in corresponding normal tissues. As a first step toward analyzing the regulation of expression of CEA at the transcriptional level, we have isolated and characterized a cosmid clone (cosCEA1), which contains the entire coding region of the CEA gene. A close correlation exists between the exon and deduced immunoglobulin-like domain borders. We have determined a cluster of transcriptional starts for CEA and the closely related nonspecific cross-reacting antigen (NCA) gene and have sequenced their putative promoters. Regions of sequence homology are found as far as approximately 500 nucleotides upstream from the translational starts of these genes, but farther upstream they diverge completely. In both cases we were unable to find classic TATA or CAAT boxes at their expected positions. To characterize the CEA and NCA promoters, we carried out transient transfection assays with promoter-indicator gene constructs in the CEA-producing adenocarcinoma cell line SW403, as well as in nonproducing HeLa cells. A CEA gene promoter construct, containing approximately 400 nucleotides upstream from the translational start, showed nine times higher activity in the SW403 than in the HeLa cell line. This indicates that cis-acting sequences which convey cell type-specific expression of the CEA gene are contained within this region.

Usefulness of a new tumor marker, Span-1, for the diagnosis of pancreatic cancer

Levels of serum Span-1, a new tumor marker for pancreatic cancer, were assayed in 64 patients with pancreatic cancer, 90 with nonpancreatic cancer, and 254 with nonmalignancies, involving 55 healthy controls. Furthermore, Span-1 was compared with other tumor markers (CA19-9, carcinoembryonic antigen [CEA], and DU-PAN-2). Frequency of elevated Span-1 levels was 81.3% in pancreatic cancer. False-positive elevations of serum Span-1 levels were rather common in liver cirrhosis (53.8%) and chronic hepatitis (26.3%). The sensitivity, specificity, and efficiency of this assay for pancreatic cancer, was 81.3%, 75.6%, and 76.5% against all subjects without pancreatic cancer, respectively. In comparison with other markers, sensitivity of Span-1 tended to be highest with similar specificity to those of CA19-9 and CEA. The Span-1 assay has a high sensitivity and specificity for pancreatic cancer. It is almost equivalent to CA19-9 assay. However, this assay is not specific for chronic liver diseases.

Diagnostic value of serum tumor markers in skeletal metastasis of carcinomas

Levels of serum tumor markers including tissue polypeptide antigen (TPA), CA 15-3, CA 19-9, squamous cell carcinoma antigen, carcinoembryonic antigen, alpha-fetoprotein, and PAP were measured in 26 patients with bone metastasis and in 9 patients with primary bone tumors. More than one markers was elevated in 19 of the 26 patients with bone metastasis, although there was no elevation of the markers in 3 patients with renal cell carcinoma. TPA was the most sensitive marker in the diagnosis of metastasis. CA 15-3 was also a sensitive marker in this study, since metastasis from breast carcinoma may be the most common of all metastases in the skeleton. On the other hand, alpha-fetoprotein was uniformly unresponsive except in one case of gastric cancer. Combinations of markers are valuable for metastasis screening tests. No definite correlations were found between the markers in this study. On the other hand, there was a slight elevation of the markers observed in two of the nine patients with primary bone lesions. Serum tumor markers are useful in the diagnosis of bone metastasis to differentiate it from primary bone lesions. Especially in solitary bone lesions, serum markers may be the only way to make a differential diagnosis between the two.

Carcinoembryonic antigen: function in metastasis by human colorectal carcinoma

Carcinoembryonic antigen (CEA) is a glycoprotein that has been useful as a tumor marker to predict recurrence in gastrointestinal malignancies, but whose biological function has not been elucidated. With the recent evidence that CEA is a member of the immunoglobulin supergene family, CEA may be involved in intercellular recognition and binding. This review examines the role that CEA plays in the development of metastases by colorectal carcinoma.

Carcinoembryonic antigen: a rat model

It has been shown that a TAA termed rat CEA had the tissue distribution and physico-chemical properties similar to those of human CEA. In addition, it has been demonstrated that these two antigens shared antigenic determinants. These findings supported our contention that rat CEA and human CEA are analogous moieties. The production of CEA-specific autoantibodies and the induction of resistance to CEA-positive rat tumors after immunization of rats with extracts containing rat CEA raises the possibility that human CEA may be immunogenic in man. Treatment with heat, proteolytic enzymes and periodate oxidation revealed that rat CEA, similar to human CEA contained both carbohydrate and protein epitopes. The epitopes shared by rat and human CEA that were detectable by the monkey anti-human CEA serum appeared to be carbohydrate, whereas the epitopes on rat CEA with which the rat mAb combined appeared to be protein, and those detected by the rabbit anti-rat CEA serum appeared to be carbohydrate, as well as protein. These studies also indicated that, although the rat, rabbit and monkey produced antibodies specific for rat CEA, the epitopes detectable by antibodies from one species appeared to be distinct from those detectable by antibodies from the other two species. These observations have important implications in studies on human CEA. Its use as a reliable diagnostic marker for malignancy hinges on the detection of tumor-specific epitopes on the molecule. Such epitopes have not yet been clearly identified by antibodies produced in foreign species. Indeed, our finding that the rat mAb to rat CEA bound only to tumor extracts and not to extracts of normal tissues, including intestinal tissues, suggests that human beings would be the most likely source of a tumor-specific antibody to human CEA. In future studies, the role antibodies play in immunity against CEA-positive tumors will be explored and attempts will be made to determine whether all of the serologically detectable epitopes on rat CEA can induce tumor resistance, or whether this activity is limited to epitopes detectable only by rat antibodies. This information could have important implications in the use of human CEA in the immunotherapy of malignancies.

CA 72-4 radioimmunoassay for the detection of the TAG-72 carcinoma-associated antigen in serum of patients

Monoclonal antibody (MAb)B72.3 has been used to detect the presence of TAG-72 in the serum of carcinoma patients. We have developed new anti-TAG-72 MAbs and have selected one of these, CC49, as the "catcher" MAb with 125I-B72.3 as the detecting antibody in a double-determinant immunoradiometric assay. This combination enabled the development of a sequential assay (designated CA 72-4) that showed optimal quantitative properties as demonstrated by such parameters as linear dose-response, high re-producibility, and lack of serum-matrix and "hook-back" effects. Only 3.5% of 744 normal sera and 6.7% of 134 sera from patients with benign gastrointestinal diseases had TAG-72 levels greater than 6 U/ml. Approximately 40% of 303 patients with gastrointestinal malignancies had serum TAG-72 levels of greater than 6 U/ml (55% of the patients with advanced disease). Thirty-six percent of patients with adenocarcinomas of the lung and 24% of patients with ovarian cancer (53% stage IV patients) also had elevated serum TAG-72 levels. A poor correlation was found between the carcinoembryonic antigen (CEA) and TAG-72 values of sera obtained from gastric cancer patients. Thirty-four percent of CEA negative cases were scored positive in the CA 72-4 assay, suggesting the complementarity of the CA 72-4 assay to CEA assays in the analysis of sera from patients with certain malignancies.

Tumor markers carcinoembryonic antigen, CA 50, and CA 19-9 and squamous cell carcinoma of the esophagus. Pretreatment screening

Pretreatment serum levels of the tumor markers carcinoembryonic antigen (CEA), CA 50, and CA 19-9 in 95 patients with squamous cell carcinoma of the esophagus and 32 age-matched controls were compared. Thirty-nine percent of the cancer patients showed elevated (greater than or equal to 5 micrograms/l) serum CEA levels, 41% had elevated (greater than or equal to 17 U/ml) CA 50 levels, and 13% showed elevated (greater than or equal to 37 U/ml) CA 19-9 levels. The tumor markers showed a considerable degree of complementarity, and combined tumor marker analysis increased the sensitivity to 59%. Raised CEA levels were found significantly more frequently in intrathoracically localized tumors than in cervical cancers. Patients surviving less than 6 months showed a higher rate of elevated CEA assays than those who survived 6 to 18 months. No certain correlation was established between tumor marker elevation and tumor stage or tumor differentiation.

Profiles of epitope-defined markers in sera from patients with testicular germ cell tumors

Epitope-defined tumor markers of AFP (FA), HCG (PM), PLAP (H7) and CEA (D/AH) were determined by monoclonal antibodies in sera of patients with germ cell tumors of the testis. Characteristic profiles of PLAP (H7) were seen in localized and metastatic seminoma and in sera of patients with mixed tumors with seminoma components. PLAP (H7) levels started to rise 10 months before clinical detection of recurrence in one case. Persisting elevated levels of PLAP (H7) in several cases were indicative of metastatic seminoma. PLAP (H7) occurred rarely in sera of patients with metastasing non-seminomatous tumors. AFP (FA) detected in seminoma sera led to identification of non-seminomatous disease in one case. High AFP (FA) alone occurred in yolk sac tumors, HCG (PM) with AFP (FA) or PLAP (H7) in patients where the tumors had components of teratoma and/or embryonal carcinoma, moderately elevated levels of AFP (FA) and sometimes also HCG (PM) occurred.

Villin: a cytoskeletal protein and a differentiation marker expressed in some human adenocarcinomas

We studied the expression of villin, a microfilament-associated, actin-binding protein typical of brush-border microvilli, in a variety of human carcinomas by applying immunofluorescence microscopy to frozen sections and immunoblotting methods to tissue extracts using a rabbit antiserum and a monoclonal antibody specific for villin. All of the 24 primary and metastatic colorectal adenocarcinomas tested were uniformly and strongly positive for villin, with the immunocytochemical labeling concentrated at the luminal cell margin. In poorly differentiated tumor areas, rudimentary tubules were stained. All of the six tubular adenocarcinomas of the stomach studied as well as two adenocarcinomas of the gall bladder and a hepatocellular carcinoma were also villin-positive. Villin was detectable in 12 of 14 adenocarcinomas of the pancreas; in some of these cases, its distribution was heterogeneous. Among 21 renal cell carcinomas investigated, positivity for villin was seen in nine of 13 clear cell tumors (especially those of grade II), and in all four chromophilic cell tumors; however, all four chromophobe cell tumors studied were negative. Four of 11 endometrial but none of nine ovarian carcinomas were (uniformly or focally) villin positive. Of 18 adenocarcinomas of the lung studied, one was uniformly and four focally positive for villin, while the remainder were negative. All of the other epithelial tumors studied, including 12 adenocarcinomas of the breast and seven epithelial or biphasic pleural mesotheliomas, were villin negative. Our results show that the expression of villin in intestinal epithelial cells is consistently maintained in their corresponding carcinomas, even when the organized brush-border structure has been lost. The presence of villin in some endometrial and pulmonary adenocarcinomas--in contrast to its absence in the respective normal epithelia--suggests that this protein is newly expressed during hyperplasia, dysplasia, or carcinogenesis. Determining the presence or absence of villin and its immunocytochemical staining pattern in metastatic adenocarcinomas may be of some help in determining the type and site of the primary tumor.

The structural relationship of blood group-related oligosaccharides in human carcinoma to biological function: a perspective

Blood group-related oligosaccharides have been isolated from a limited number of carcinomas. The carcinoma-associated oligosaccharides show chain elongation, for example due to repeating Gal 1,4 GlcNAc 1,3 sequences, or a higher degree of branching, which permit increased sialylation and fucosylation. Abnormal carbohydrate structures have been demonstrated on tumor cell membranes by immunological techniques, which suggests deletion of ABH, accumulation of 'crypt' antigens such as I and T antigens, and abnormal expression of Lewis antigens. Changes in carcinoma-associated oligosaccharides can result from altered biosynthetic processing in the Golgi apparatus or the occurrence of abnormal tumor glycosyltransferase isoenzymes. Structural alterations of oligosaccharides on the tumor cell membrane are related to the regulation of tumor growth, cell-cell interaction, cell differentiation, and metastasis. Glycoproteins secreted by tumor cells into the circulation evoke cellular and humoral immunity and cause immune suppression by binding to cytotoxic T lymphocytes and lymphocyte subsets. The relationship of oligosaccharide structures to biologic function awaits elucidation.

Comparison of circulating MAM-6 and CEA levels and correlation with the estrogen receptor in patients with breast cancer

MAM-6 and CEA serum levels of 136 staged breast cancer patients were determined concomitantly. The sensitivities of the MAM-6 assay using monoclonal antibody (MAb) 115D8 and a polyclonal CEA assay were equally low and only a limited number of patients with early stages of breast cancer showed elevated antigen levels. However, the sensitivity rose to 75% for MAM-6 and to 60% for CEA in stage-IV patients. The levels of both antigens correlated well in the sera of these patients, although MAM-6 serum levels were elevated more frequently, while only in a few cases were MAM-6-negative sera CEA-positive. A group of stage-II breast cancer patients who eventually developed distant metastases was followed in a longitudinal study. Tumor progression or regression was clinically determined and compared with the MAM-6 and CEA serum levels in order to establish the value of each assay for the monitoring of breast cancer. The course of the disease correlated significantly better with changes in MAM-6 antigen levels than with changes in CEA levels (p less than 0.05), being 79% and 42% respectively. The lower correlation of CEA levels with the course of the disease was mainly due to a lower sensitivity of the CEA assay for advanced breast cancer. The specificity of changing MAM-6 and CEA levels was not significantly different. The main advantage of the MAM-6 assay over the CEA assay is the higher sensitivity of the former. In a preliminary study among stage-IV patients a correlation was found between elevated MAM-6 levels and the presence of the estrogen receptor in the primary tumor.

Capture and detection of carcinoembryonic antigen on antibody coated beads used in enzyme immunoassay

We have evaluated antibody coated beads for capture and detection of carcinoembryonic antigen (CEA). Assay parameters of time, temperature, buffer molarity, specificity of antibody on the bead and reagent addition sequence have been studied. Optimal assay kinetics occurred at a temperature of 45 degrees C and a buffer molarity of 0.1M or above. The type and quantity of antibody on the bead surface were also critical to optimal CEA detection. Beads coated with baboon or goat anti-CEA antibody were able to capture a higher percentage of CEA than monoclonal mouse anti-CEA antibody or guinea pig anti-CEA antibody. The sequence of addition of CEA, anti-CEA antibody coated bead, and anti-CEA-horse radish peroxidase conjugate was important for optimal CEA detection. Formation of an immune complex of CEA with the anti-CEA horse radish peroxidase conjugate prior to capture of the CEA on an antibody bead resulted in the optimal detection of CEA.

Carcinoembryonic antigen (CEA) in blood in cases of pneumonia

Serum levels of carcinoembryonic antigen (CEA) were analysed in patients with pneumonia of different etiology. Significant (p less than 0.01) increases in blood CEA levels occurred in all groups of pneumonia of bacterial etiology, i.e., pneumococcal, gram-negative or chlamydial. In viral pneumonia similar increases were observed, but the changes were not statistically significant, probably due to the small number of patients. In pneumonia of unknown etiology CEA behaved as in bacterial pneumonias. Maximal values between 5 and 15 micrograms/l CEA were common in pneumonia, the basal level usually being less than 5 micrograms/l. The severity of pneumonia, as judged by maximal erythrocyte sedimentation rate, correlated weakly with CEA levels in the bacterial group (p less than 0.05). In pneumonias of unknown etiology white blood cell counts and C-reactive protein levels correlated significantly with maximal CEA (p less than 0.01). In conclusion we have demonstrated, that in pneumonias of different etiology strongly but transiently increased blood CEA levels are the rule. The severity of pneumonia is not clearly correlated with CEA levels.

Carcinoma of the ureter with extensive squamous differentiation and positive immunoperoxidase staining for carcinoembryonic antigen: a case report

A case of ureteral carcinoma with extensive squamous differentiation and positive staining for carcinoembryonic antigen by the immunoperoxidase method is presented. Ureteral carcinoma should be added to the list of tumors that may produce carcinoembryonic antigen or antigen-like material.