Monoclonal antibody M3 used in tissue polypeptide-specific antigen assay for the quantification of tissue polypeptide antigen recognizes keratin 18

Time-Course Changes of Serum Keratin Concentrations after Liver Transplantation: Contrasting Results of Keratin-18 and Keratin-19 Fragments

Objective

Under normal conditions, adult hepatocytes express only keratin-8 (K8) and keratin-18 (K18), whereas cholangiocytes also express K19. In this study, we delineate the pattern of normal time-course changes in serum K19 and K18 levels after liver transplantation. Patients and Methods. Serum levels of the K19 fragment CYFRA 21-1 and the K18 fragments tissue polypeptide specific antigen (TPS) and M30 (a neoepitope that is generated after caspase cleavage during apoptosis) were measured at baseline and at regular intervals (up to 6 months) after liver transplantation in 11 adult patients.

Results

There was a gradual decrease in serum K19 concentrations from baseline values after transplantation, following a time-course pattern similar to that of serum bilirubin. In contrast, serum concentrations of K18 fragments increased markedly shortly after transplantation and gradually decreased thereafter, following a time-course pattern similar to that of serum transaminases. The increase in TPS tended to occur earlier than that in M30, suggesting an initial predominance of hepatocyte necrosis followed by a predominance of apoptosis in the first days after transplantation. Five patients presented posttransplant complications (acute rejection in three cases and HCV recurrence in two cases). An early increase in serum K19 concentrations was observed in all cases. An increase in serum concentrations of K18 fragments (M30 and TPS) was observed in the two cases with HCV recurrence and was more variable in the three cases with acute rejection.

Conclusions

Serum concentrations of K19 and K18 fragments follow a dissimilar pattern of time-course changes after liver transplantation. The diagnostic value of variations in these normal patterns should be addressed in future studies.

Mucins and Cytokeratins as Serum Tumor Markers in Breast Cancer

Structural and functional characteristics of mucins and cytokeratins are shortly described. Thereafter, those commonly used in breast cancer as serum tumor markers are considered. First CA15.3, MCA, CA549, CA27.29 mucins and CYFRA21.1, TPA, TPS cytokeratins alone or in association have been examined in different stages and conditions. Then their usefulness in monitoring disease-free breast cancer patients is evaluated. The central role of the established cut-off and critical change, the "early" treatment of recurrent disease and the potential benefit in survival are other issues that have been highlighted and discussed. The successive sections and subsections deal with the monitoring of advanced disease. In them, the current recommendations and the principal findings on using the above mentioned mucins and cytokeratins have been reported. A computer program for interpreting consecutive measurements of serum tumor markers also has been illustrated. The final part of the chapter is devoted to mucins and cytokeratins as markers of circulating and disseminated tumor cells and their usefulness for prognosis.

Serum tissue polypeptide-specific antigen is an independent predictor in breast cancer

Tissue polypeptide-specific antigen (TPS) is a tumor proliferative marker associated with cytokeratin 18. The aim of the study was to investigate the potential relationship between the preoperative serum TPS levels and the outcome in Chinese breast cancer patients. 975 consecutive female patients, affected by invasive breast cancer under investigation from January 2005 to December 2011, had their TPS levels measured with a one-step solid phase radiometric sandwich assay detecting the M3 epitope on cytokeratin 18 fragments. The cut-off value was 80U/L. The average age diagnosed with breast cancer was 48, ranging from 23 to 71. About 19% (185) patients displayed an elevated preoperative TPS level (>80U/L) associated with older age (>45), advanced cancer stage, larger tumor size (>2cm), axillary lymph node metastasis, negative progesterone receptor status, and positive HER2 status. In addition, preoperative TPS levels were also significantly connected with recurrence (p<0.05), particularly distant metastasis and visceral metastasis. The mean preoperative TPS level was 68.4±116.43U/L (range 0-1839U/L). In multivariate analysis, high preoperative TPS level was recognized as an independent prognostic factor for disease-free survival (p<0.001 and overall survival (p=0.023). From these results we conclude that the serum preoperative TPS level may be a valuable and independent marker for breast cancer.

Keratins: markers and modulators of liver disease

PURPOSE OF REVIEW

Keratins are a subgroup of intermediate filaments expressed in the epithelia. Keratins emerged as important tissue-protecting genes and keratin variants cause/predispose to development of more than 50 human disorders. Our review focuses on the importance of keratins in context of liver disease.

RECENT FINDINGS

K8/K18 variants are found in approximately 4% of white population and predispose to development and adverse outcome of multiple liver diseases. K8/K18 are major constituents of Mallory-Denk bodies, that is inclusions found in alcoholic and nonalcoholic steatohepatitis (NASH) and dysregulated keratin expression, K8 hyperphosphorylation, misfolding and crosslinking via transglutaminase 2 facilitate aggregate formation. Necrosis-generated and apoptosis-generated keratin serum fragments are emerging as important noninvasive markers of multiple liver diseases, particularly NASH. Keratins are established markers of tumor origin and in hepatocellular carcinoma, K19 expression is associated with poor prognosis.

SUMMARY

Keratins are established tumor markers and are widely used as noninvasive markers of liver injury. In addition, the data that have become available in recent years have greatly advanced our understanding of keratins as modifiers of liver disease development.

Synergistic effect of alcohol consumption and body mass on serum concentrations of cytokeratin-18

BACKGROUND

Cytokeratin-18 is an essential component of the cytoskeleton of epithelial cells (including hepatocytes). Serum concentrations of cytokeratin-18 (tissue polypeptide-specific antigen [TPS]) are used as a marker of epithelial neoplasms. Here, we investigated the potential interaction between alcohol and obesity in relation to serum TPS concentrations.

METHODS

Alcohol consumption, body mass index, and components of metabolic syndrome were measured in a random sample (n = 420) of the adult population (aged 18 to 92 years, 45% men) from a single municipality. Regular alcohol intake of >20 g/d (women) or >30 g/d (men) was considered risky drinking. Serum TPS was measured with a commercial immunoassay.

RESULTS

Risky drinking was associated with increased serum concentrations of TPS, which was particularly evident among obese individuals. Among individuals without risky drinking, TPS concentrations were similar for all levels of body mass. Conversely, among risky drinkers, serum TPS concentrations increased in parallel with body mass (p = 0.002). The odds ratio of a high (>100 U/l) TPS concentration for the combination of risky drinking and obesity was greater than the additive effect of the 2 separate factors, after adjusting for age and sex. A similar interaction was observed between risky drinking and abdominal adiposity, a major component of the metabolic syndrome. Serum TPS concentrations were correlated with markers of liver damage. Serum TPS was not superior to standard markers (gamma-glutamyl transferase and red blood cell mean volume) for the detection of risky drinking.

CONCLUSIONS

There is a synergism between risky alcohol consumption and common metabolic disorders (particularly obesity) in relation to serum concentrations of cytokeratin-18 (TPS), which probably reflect liver disease.

Serum levels of keratin-18 fragments [tissue polypeptide-specific antigen (TPS)] are correlated with hepatocyte apoptosis in alcoholic hepatitis

Apoptosis is a major feature in alcoholic hepatitis. During apoptosis, the M30 neoepitope becomes exposed after keratin-18 cleavage. The tissue polypeptide-specific antigen (TPS) is a keratin-18 fragment that is routinely used as a tumor marker. Serum TPS levels are increased in patients with alcoholic hepatitis. The aim of this study was to investigate the possible relationship of TPS levels with hepatocyte apoptosis in alcoholic hepatitis. Thirty-one patients with alcoholic hepatitis and 22 with fatty liver were included. Hepatocyte apoptosis was evaluated by M30 immunostaining. Serum TPS levels were measured by a commercial immunoassay. The apoptotic score was higher in patients with alcoholic hepatitis than in patients with fatty liver. There was a significant correlation between the apoptotic score and TPS levels. The correlation of the apoptotic score with TPS levels was stronger than with standard liver tests. Serum TPS may be a marker of apoptosis in alcoholic hepatitis.

Tumor Markers In Biological Fluids Associated With Pregnancy

Proteins that are expressed by both malignant and healthy fetal tissues are recognized as oncofetal. These antigens are associated with cell proliferation and differentiation and are produced in high concentrations in pregnancy and malignancy. Their biological role in malignancy is the suppression of the host's immune system, while in pregnancy they affect the maternal immune response, generating maternal tolerance toward the embryo. This review describes the levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), carcinoembryonic antigen (CEA), cancer antigen 125 (CA 125), squamous cell carcinoma antigen (SCC), cancer antigen 15-3 (CA 15-3), mucin-like carcinoma-associated antigen (MCA), tissue polypeptide-specific antigen (TPS), carbohydrate antigen 19-9 (CA 19-9), and prostate-specific antigen (PSA) in maternal serum (MS), umbilical cord serum (UC), and amniotic fluid (AF) and outlines their roles in the assessment of pregnancy and malignancy. All antigens studied, except CA 15-3, are oncofetal. The presence of considerable concentrations of AFP, hCG, CEA, CA125, SCC, MCA, TPS, CA 19-9, and PSA in AF during pregnancy may be attributed to their involvement in biological functions associated with fetal development, differentiation, and maturation. MS CEA, CA 15-3, and CA 19-9, in contrast to all the others, are not influenced significantly by pregnancy and thus remain reliable tumor markers in monitoring malignancy in pregnant patients.

Cytokeratin fragments in the serum: their utility for the management of oral cancer

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy and is a major cause of cancer morbidity and mortality worldwide. Oral cancer is the most predominant malignancy in the Indian subcontinent due to the widespread habits of chewing tobacco and related products. Patients with oral tumours have a high risk of early locoregional relapse. Early detection of disease progression remains a challenging task mainly due to the lack of adequate early prognostic markers. CEA, SCC Ag, CA-125, serum cytokeratin (CK) fragments, Cyfra 21-1 (CK 19), TPS (CK 18), TPA (CK 8, 18, and 19) etc. are being used as serum markers for the prediction of prognosis of various malignancies. This review presents the available literature on serum CK markers in different malignancies evaluates their utility in the management of oral cancer, and identifies the lacunae which need to be addressed to develop sensitive and specific assays for early detection of recurrence, prognosis, and treatment monitoring.

Serum levels of cytokeratin-18 (tissue polypeptide-specific antigen) in liver diseases

OBJECTIVE

The tissue polypeptide-specific antigen (TPS, cytokeratin-18, a normal constituent of the hepatocyte cytoskeleton) is a standard tumour marker. This study aimed to evaluate serum TPS levels in patients with liver disease.

METHODS

Serum TPS was measured with a commercial immunoassay in 884 individuals (753 outpatients from a liver disease clinic, 131 patients admitted to the hospital with acute liver disease).

RESULTS

Abnormally high (> 80 U/l) TPS levels were found in 57.7% (95% CI 54.0-61.3%) of outpatients with liver disease. Elevated TPS levels were observed for all liver diseases, including fatty liver, alcoholic disease, chronic viral hepatitis, autoimmune hepatitis, cholestasis, transplantation, and hepatocarcinoma. TPS levels correlated with liver markers, particularly serum AST. In addition, TPS levels correlated with Knodell's score in patients with chronic hepatitis. TPS was increased in one-third of patients with normal liver enzyme values. Serum TPS levels decreased after specific therapy in patients with hepatitis C and autoimmune hepatitis. Abnormally high TPS levels were found in the vast majority of patients admitted to the hospital, with markedly high (> 800 U/l) values being observed in 47.5% (95% CI 36.1-55.7%) of patients with alcoholic liver disease and in 80.8% (95% CI 60.0-92.7%) of patients with acute hepatitis.

CONCLUSIONS

Serum TPS (cytokeratin-18) is elevated in patients with non-malignant liver diseases, particularly in those with prominent cytolysis. Further studies are needed to evaluate the use of TPS as a marker of liver disease.

Detection of epithelial cell death in the body by cytokeratin 18 measurement

Cell death is as important as cell division in both physiological and pathological processes. Three major types of cell death have been described: apoptosis, autophagy and necrosis. Apoptosis is a form of programmed cell death, mediated by caspases. Autophagy is an evolutionarily conserved process involving lysosomes, implicated in both cell survival and death. Necrosis is believed to be an unregulated process, followed by release of intracellular components. The epithelial-specific intermediate filament cytokeratin 18 (Kl8) has different fates depending on the type of cell death. During apoptosis, K18 is cleaved at two sites into three fragments, one of which is specifically recognized by the monoclonal antibody, M30. During autophagy K18 is reported to stay uncleaved. Necrotic cells are considered to release K18. Thus, serum levels of different forms of K18 would reflect the type of cell death occurring in the body. Two enzyme-linked immunosorbent assays have been developed: one for the cleaved fragments of K18 and the other for total K18. Detection of serum levels of cleaved and total K18 showed that the ratios between cleaved and total K18 were highly variable among patients with endometrial cancer. Monitoring serum levels of cleaved and total K18 during chemotherapy showed an association between increases in total K18 levels and clinical responses. Monitoring serum levels of K18 may be a promising approach for early detection of therapeutic effects and the levels of different forms of K18 might indicate the mode of cell death occurring in the body.

Clinical utility of cytokeratins as tumor markers

Cytokeratins, belonging to the intermediate filament (IF) protein family, are particularly useful tools in oncology diagnostics. At present, more than 20 different cytokeratins have been identified, of which cytokeratins 8, 18, and 19 are the most abundant in simple epithelial cells. Upon release from proliferating or apoptotic cells, cytokeratins provide useful markers for epithelial malignancies, distinctly reflecting ongoing cell activity. It appears that motifs in certain cytokeratins make them likely substrates for caspase degradation, and their subsequent release occurs during the intermediate events in apoptosis. The clinical value of determining soluble cytokeratin protein fragments in body fluids lies in the early detection of recurrence and the fast assessment of the efficacy of therapy response in epithelial cell carcinomas. The three most applied cytokeratin markers used in the clinic are tissue polypeptide antigen (TPA), tissue polypeptide specific antigen (TPS), and CYFRA 21-1. TPA is a broad spectrum test that measures cytokeratins 8, 18, and 19. TPS and CYFRA 21-1 assays are more specific and measure cytokeratin 18 and cytokeratin 19, respectively. By following patients with repeated testing during management, the oncologist may obtain critical information regarding the growth activity in symptomatic patients. Although their main use is to monitor treatment and evaluate response to therapy, early prognostic information particularly on tumor progression and metastasis formation is also provided for several types of cancers. Cytokeratin tumor markers can accurately predict disease status before conventional methods and offer a simple, noninvasive, cheap, and reliable tool for more efficient management.

Serum levels of tissue polypeptide specific antigen are correlated with hepatocyte cytokeratin expression in alcoholic liver disease

BACKGROUND

Serum levels of the tumor marker tissue polypeptide specific antigen (TPS, cytokeratin 18 fragments) are increased in patients with alcoholic liver disease, particularly in cases of alcoholic hepatitis. Mallory bodies, characteristic of alcoholic hepatitis, are cytokeratin 8 and 18 aggregates. The study was aimed at investigating the possible relationship of serum TPS levels with hepatocyte cytokeratin expression in patients with alcoholic liver disease.

METHODS

Twenty-four patients with alcoholic liver disease were studied. Immunohistochemical staining for cytokeratins 8 and 18 was performed in liver specimens by means of CAM 5.2 monoclonal antibody. The number of hepatocytes containing CAM 5.2-reactive cytokeratin inclusions was compared with serum TPS levels.

MAIN RESULTS AND CONCLUSIONS

The vast majority of alcoholics (95%) showed increased (>100 units/liter) serum TPS levels. Serum TPS levels were significantly correlated with the number of hepatocyte cytokeratin inclusions. Serum TPS levels can predict hepatocyte cytokeratin expression in patients with alcoholic liver disease.

[Study of the cytosolic concentrations of the tissue poly-peptide specific (TPS) antigen in infiltrating ductal carcinomas of the breast. Positive relationship with hormone dependency and negative with cellular proliferation]

INTRODUCTION

The tissue-specific polypeptide antigen (TPS) is an epitope of the tissue polypeptide antigen (TPA) which is defined by the M3 monoclonal antibody and is related to cytokeratin 18. Several groups have demonstrated its value as a useful parameter in the follow-up of some tumors. This work has aimed to study the TPS cytosolic levels in infiltrating ductal carcinomas of the breast (IDC) and their possible correlations with other clinical-biological parameters.

PATIENTS AND METHODS

The TPS was determined by means of an immunoradiometric assay (Beki Diagnostics. Sweden). Other parameters included in the study were the estrogen receptors (ER), progesterone receptors (PR), pS2, cathepsin D, tissue-type plasminogen activator (t-PA), tumor size, axillary lymph node involvement, distant metastases, histological grade, ploidy and S-phase.

RESULTS

The TPS cytosolic levels ranged from 1.8 to 606.3 KU/mg prt. (median 110.2) and had a significant correlation with the ER (r: 0.721), PR (r: 0.287), cathepsin D (r: 0.550) and t-PA (r:0.436). The TPS positive (> 110.2 KU/mg prt.) carcinomas had higher levels of ER (p: 0.001), PR (p: 0.021), pS2 (p: 0.058), cathepsin D (p: 0.000) and t-PA (p: 0.053) than the TPS negative tumors. When the IDC were classified according to S-phase values, we observed that the positive cases (S-phase > 8.1%, which represents the median value of all carcinomas) had lower levels of TPS (p: 0.046) than the negative tumors. Likewise, the GoG1 cellular fraction correlated positively and significantly with the TPS cytosolic levels (p: 0.000).

CONCLUSIONS

Based on our results, we suggest that there is a positive correlation between the TPS cytosolic levels and hormone-dependence parameters, as well as an inverse correlation between these and the cellular proliferation parameters. Based on the above, we consider that it is worthwhile to carry out further studies on cytosolic TPS in order to investigate its possible value as a prognostic parameter in breast carcinomas.

Serum tissue polypeptide specific antigen (TPS): a complementary tumor marker to CA 15-3 in the management of breast cancer

The efficacy of CEA and CA15-3 tumor markers in monitoring breast cancer was evaluated in 1365 patients with either benign (n = 534) or malignant (n = 831) breast diseases. Thirty-nine breast cancer patients were monitored before and after neoadjuvant chemotherapy. Three hundred forty-nine patients were monitored during post-surgical follow-up for either a minimum of 5 years or until time of recurrence. Twenty-one patients with metastases were also monitored during chemotherapy. Elevated CA 15-3 and TPS levels were found in 28.6% and 30.0% of patients. CA 15-3 and TPS sensitivities rose to 71.9% and 66.3% in metastatic patients, respectively. The addition of TPS to CA 15-3 increased the sensitivity up to 44.4% in the overall population, and to 87.6% in patients with metastases. During post-surgical follow-up CA 15-3 was elevated in 65.7% and TPS in 61.3% of patients with recurrence. The combination of TPS and CA 15-3 increased the overall sensitivity by 12.7%. Longitudinal monitoring of metastatic patients undergoing chemotherapy demonstrated that, when positive, both CA 15-3 and TPS paralleled response to treatment. TPS monitoring may provide additional value when used in combination with CA15-3 during post-surgical follow-up of breast cancer patients.

Urinary tissue polypeptide-specific antigen for the diagnosis of bladder cancer

OBJECTIVES

To evaluate the diagnostic characteristics of the urinary measurement of cytokeratin tissue polypeptide-specific antigen (TPS) for the detection of bladder cancer.

METHODS

Three hundred thirty-five individuals in five groups were studied: group 1, subjects with microhematuria under suspicion for primary bladder cancer; group 2, patients being followed up with scheduled cystoscopic examinations; group 3, patients in follow-up receiving chemotherapy instillations; group 4, patients with other urologic diseases; and group 5, healthy subjects. Urine samples belonging to subjects from groups 1, 2, and 3 were collected immediately before cystoscopy. Additionally, patients from groups 2 and 3 were monitored with urinary TPS for a minimum period between two cystoscopies. TPS was measured by an enzyme immunosorbent assay.

RESULTS

Receiver operating characteristic analysis gave a sensitivity of 64% and a specificity of 84% at a threshold value of 279 U/L. The positive and negative predictive value was 66% and 82%, respectively; accuracy was 77%. TPS could discriminate the presence of bladder tumor sooner than the scheduled cystoscopies in 9 of 19 follow-up patients with recurrence. False-positive results during follow-up were found in 112 urine samples, one third of which were associated with urinary tract infections. TPS did not appear to be specific for bladder cancer, with elevated results in 45% of patients from group 4, which might lead to clinical misinterpretation of urinary TPS results.

CONCLUSIONS

Urinary TPS might provide additional information for the detection of bladder cancer as an adjunct to cystoscopy. Considering the false-positive rates, different urologic diseases should be ruled out before making clinical decisions on the basis of elevated urinary TPS results.

Clinical evaluation of serum tissue polypeptide specific antigen in patients with thyroid carcinoma

There is no specific marker for diagnosis of thyroid cancer with the exception of carcinoembryonic antigen (CEA) and calcitonin for medullary thyroid carcinoma. Tissue polypeptide antigen (TPA) is known to be a diagnostic marker of malignant neoplasms. TPA is also one of the tumor markers for thyroid cancer, but serum TPA shows poor specificity because of polyclonal antibody. Tissue polypeptide specific antigen (TPS) is detected by the monoclonal antibody M3, directed at 1 of the 35 epitopes in TPA. TPS appears in proliferative tumor cells. We examined 72 patients (32 thyroid carcinoma, 20 thyroid adenoma, 5 adenomatous goiter, and 15 diffuse goiter) and 24 healthy volunteers for serum TPS, TPA, and thyroglobulin (Tg). The TPS in thyroid carcinoma was significantly higher than in healthy controls and thyroid adenoma (p < 0.05). The mean value of TPS for all diseases except thyroid carcinoma was below the cutoff value (95 U/L). The TPS sensitivity, specificity, and accuracy for thyroid carcinoma was 37.5%, 100%, and 64.9% respectively. There were no significant differences in mean values of serum Tg and TPA between thyroid carcinomas and adenomas. Positive rates of tissue TPS expression in thyroid carcinomas and adenomas were 87.5% (7/8) and 14.3% (1/7), respectively. The positive rates for serum TPS and immunoreactive TPS in the tissue correlated significantly (p < 0.0001). It is concluded that TPS is a useful marker for diagnosis of thyroid carcinoma.

Cytokeratin markers in malignant pleural mesothelioma

Previously available serum tumor markers had a low clinical value in malignant pleural mesothelioma (MPM). The recently developed tissue polypeptide-specific antigen (TPS) and CYFRA 21-1 assays identify the soluble cytokeratin 18 and 19 fragments, respectively. In MPM these cytokeratins are expressed and may therefore be used as serum tumor markers. In this preliminary study, TPS and CYFRA 21-1 assays were evaluated to determine their potential for management of patients with MPM. Carcinoembryonic antigen (CEA) was evaluated as an additional marker. The study group consisted of 95 patients with benign lung and pleural diseases (BLPD), 14 patients with MPM, 41 patients with adenocarcinoma of lung (AC), and 40 patients with squamous cell carcinoma of lung (SQC). The utilized cutoff points corresponded to a 95% specificity for patients with BLPD. In MPM, TPS showed greater sensitivity (64.3%) than CYFRA 21-1 (50.0%), while CEA showed no sensitivity. In SQC, the marker CYFRA 21-1 had the highest sensitivity (52.5%), whereas in AC the most sensitive marker was CEA (56.1%). Significantly lower levels of CEA were found in MPM compared with BLPD (p < 0.001) or AC and SQC (p < 0.0001). Conversely, TPS levels in MPM were significantly higher than in SQC (p < 0.05). Close correlation of various individual pretreatment marker levels was observed only between TPS and CYFRA 21-1, both in MPM (r = 0.84; p < 0.001) and in non-small cell lung cancer (NSCLC) (r = 0.71; p < 0.001). In serial determinations of the markers during chemotherapy of MPM (n = 10), TPS and CYFRA 21-1 were shown to demonstrate more or less the same pattern of reactivity, although the changes in the TPS levels better reflected the clinical response to therapy. In conclusion, TPS seems to be a more sensitive marker than CYFRA 21-1.

Tissue polypeptide specific antigen in the follow-up of ovarian and cervical cancer patients

This retrospective study includes 425 serological examinations of 40 patients with epithelial ovarian cancer and 356 serological examinations of 33 patients with squamous cell cervical cancer. The serum levels of the tumor markers tissue polypeptide specific antigen (TPS), carbohydrate antigen 125 (CA 125) and squamous cell carcinoma antigen (SCC) were determined. Cutoff values of 93 U/l for TPS, 3 microg/l for SCC and 37 U/ml for CA 125 were selected according to the 95th percentile of serum concentrations measured in healthy control patients. For ovarian cancer sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of TPS were 67%, 84%, 59% and 90%, respectively. In 27 patients with recurrent ovarian cancer, CA 125 and TPS showed lead time effects in 8 and 11 cases, respectively. The combination of CA 125 and TPS provided lead time in 14 cases of recurrent disease with a time range from I to 23 months (median 3.9 months). In cervical cancer, TPS showed a sensitivity, specificity, PPV and NPV of 64%, 90%, 85% and 68%, respectively. In 16 patients with recurrent cervical cancer, SCC and TPS showed lead time effects in 7 and 8 cases, respectively. The combination of SCC and TPS provided lead time effects in 12 cases with a time range from 0.5 to 6 months (median 3.5 months). Our data indicate that TPS is a valuable tool in the follow-up of patients with ovarian or cervical cancer. However, TPS does not appear to be adequate to replace tumor markers CA 125 and SCC.

Evaluation of tissue polypeptide specific antigen, CYFRA 21-1, and carcinoembryonic antigen in nonsmall cell lung carcinoma: does the combined use of cytokeratin markers give any additional information?

BACKGROUND

Recently developed tissue polypeptide specific antigen (TPS) and CYFRA 21-1 assays determine the soluble cytokeratin 18 and 19 fragments, respectively, in serum. The authors compared the value of TPS, CYFRA 21-1, and carcinoembryonic antigen (CEA) for the diagnosis, staging, prognosis, and monitoring of patients with nonsmall cell lung carcinoma (NSCLC).

METHODS

The study included 85 patients with benign lung diseases and 94 patients with NSCLC. TPS, CYFRA 21-1, and CEA serum levels were measured with commercial kits.

RESULTS

The following were demonstrated: 1) CYFRA 21-1 and TPS levels, but not CEA levels, differed significantly between NSCLC patients with operable disease (Stages I-IIIA) and those with inoperable disease (Stages IIIB-IV). 2) The correlation coefficient between CYFRA 21-1 and TPS increased with the progression of NSCLC from Stages I-IIIA (r = 0.41, P = 0.04) to Stages IIIB-IV (r = 0.70, P < 0.001). 3) Multivariate analysis identified TPS and CYFRA 21-1 as significant predictors of survival, with relative risks of 2.57 (P = 0.001) and 2.05 (P = 0.01), respectively. For cases in which both cytokeratin markers were positive, the relative risk was 6.4 (P < 0.0001) compared with cases in which both were negative. 4) For the group with inoperable disease, the combined use of TPS and CYFRA 21-1 allowed for the definition of 3 sets of patients with significantly different median survival times (14.3 months vs. 7.4 months vs. 2.6 months). 5) The percentages of marker evaluations concordant with results of clinical assessments of response to therapy were 75.0%, 72.2%, and 61.1% for CYFRA 21-1, TPS, and CEA, respectively.

CONCLUSIONS

These findings suggest that, for NSCLC patients, CYFRA 21-1 and TPS are significant prognostic factors and effective monitors of therapy. The combined use of these cytokeratin markers may provide additional information for prognosis.

Quantification of somatic and spermatogenic cell proliferation in the testes of ruminants, using a proliferation marker and flow cytometry analysis

We compared 2 methods for the quantification of proliferation in somatic and spermatogenic compartments of post mortem-collected testes in cattle and roe deer. Proliferation was evaluated by estimation of the tissue polypeptid specific antigen (TPS) using an ELISA. This proliferation-specific marker was detected in homogenized cells after selective enrichment of different cell types by density gradient centrifugation. The haploid, diploid and tetraploid cells were monitored by one-parameter flow cytometry and analyzed for mitotic cell cycle. Somatic and spermatogenic cells were discriminated by dual-parameter flow cytometry after DNA staining with propidium iodide and selective labelling of stromatic cells with a vimentin antibody. The TPS was related to the ploidy of cells and their somatic or spermatogenic type. High concentrations of TPS were found in both species. The TPS values varied with different contents of spermatogenic and somatic cells in the fractions of the density gradient. The TPS was positively correlated with spermatogenic cells in the G2/M phase of mitotic cycle (r = 0.474; P < 0.01) and negatively correlated with somatic cells (r = -0.676; P < 0.0001) in roe deer (n = 40). Discrimination of germinative and stromatic cells in the G2-M phase showed their varying proliferation during the annual cycle in roe deer. The quantification of tetraploid spermatogenic cells allowed the calculation of an exact meiotic transformation (ratio haploid:tetraploid cells). In conclusion, TPS indicates proliferation in the germinative compartment of the testes. However, this marker provides only relative values, without information on the number and type of proliferating cells. Dual-parameter flow cytometry using specific staining for vimentin proves to be a better method for studying changing mitotic and meiotic steps during the involution and recrudescence of testes in seasonally breeding ruminants, as it relates proliferative processes directly to both spermatogenic and somatic cells.

Functional analysis of mouse keratin 8 in polyoma middle T-induced mammary gland tumours

Keratin 8 and 18 are commonly used as tumorigenic markers for various types of carcinomas. They are known to be involved in cell migration, cell invasiveness, plasminogen activity and drug and radiation resistance. To ascertain a potential function for simple epithelium keratins in mammary adenocarcinoma in vivo, keratin-8-deficient mice (mK8) were mated with transgenic mice carrying the middle T oncogene driven by the MMTV promoter. The resulting mK8 knockout and control progeny carrying the middle T transgene developed mammary gland tumours with the same incidence. However, the onset of palpable mammary gland tumours occurred earlier in mK8 mutant than in control mice. This effect was prominent in males where the onset in control animals is delayed overall, because of the lower hormonal inducibility of the MMTV promoter. Metastatic foci were observed in the lungs of all females and of a few males, independently of the genotype. Histological analysis revealed no morphological differences of the tumorigenic cells in primary tumours nor in metastatic foci. As expected, keratin 8 was absent in the mK8 tumours. Keratin 7 (mK7), keratin 18 (mK18) and keratin 19 (mK19) protein were observed in both primary and metastatic foci. These results constitute the first in vivo analysis of the role of simple epithelium keratins in mammary carcinogenesis. It demonstrates that the latency, but not the incidence nor the morphological features, of PyV middle T-induced mammary gland tumours is affected by keratin 8 deficiency.

Caspase cleavage of keratin 18 and reorganization of intermediate filaments during epithelial cell apoptosis

Keratins 8 (K8) and 18 (K18) are major components of intermediate filaments (IFs) of simple epithelial cells and tumors derived from such cells. Structural cell changes during apoptosis are mediated by proteases of the caspase family. During apoptosis, K18 IFs reorganize into granular structures enriched for K18 phosphorylated on serine 53. K18, but not K8, generates a proteolytic fragment during drug- and UV light-induced apoptosis; this fragment comigrates with K18 cleaved in vitro by caspase-6, -3, and -7. K18 is cleaved by caspase-6 into NH2-terminal, 26-kD and COOH-terminal, 22-kD fragments; caspase-3 and -7 additionally cleave the 22-kD fragment into a 19-kD fragment. The cleavage site common for the three caspases was the sequence VEVD/A, located in the conserved L1-2 linker region of K18. The additional site for caspases-3 and -7 that is not cleaved efficiently by caspase-6 is located in the COOH-terminal tail domain of K18. Expression of K18 with alanine instead of serine at position 53 demonstrated that cleavage during apoptosis does not require phosphorylation of serine 53. However, K18 with a glutamate instead of aspartate at position 238 was resistant to proteolysis during apoptosis. Furthermore, this cleavage site mutant appears to cause keratin filament reorganization in stably transfected clones. The identification of the L1-2 caspase cleavage site, and the conservation of the same or very similar sites in multiple other intermediate filament proteins, suggests that the processing of IFs during apoptosis may be initiated by a similar caspase cleavage.

Tissue polypeptide-specific antigen in pediatric patients: assessment of normal values

Measurement of serum concentrations of tissue polypeptide-specific Antigen (TPS) has been demonstrated to the useful in diagnosis and monitoring of adult epithelial tumors. So far, no data have been available on normal or pathologic TPS values in children. Therefore, the present study was designed to evaluate the normal values of TPS in childhood. Using a commercial enzyme linked immunosorbent assay (ELISA) kit, serum TPS was determined in 361 healthy children. Median (M) TPS was found to be 107 U/l at birth (n = 124). By the end of the first week, the value rose to M = 150 U/l (n = 68) and then continuously decreased with age (1 week-1 year, n = 45, M = 88 U/l; 1-7 years, n = 75, M = 51 U/l) until reaching the adult level (8-18 years, n = 49, M = 34 U/l). Additionally, the serum TPS values of 45 mothers right after delivery (M = 161 U/l) were assessed, and there was no correlation to the marker levels determined in the cord blood of their children. The age-dependent distribution of serum TPS in healthy children must be taken into account in the clinical application of this tumor marker.

Tissue polypeptide-specific antigen in pediatric patients: assessment of normal values

Measurement of serum concentrations of tissue polypeptide-specific Antigen (TPS) has been demonstrated to the useful in diagnosis and monitoring of adult epithelial tumors. So far, no data have been available on normal or pathologic TPS values in children. Therefore, the present study was designed to evaluate the normal values of TPS in childhood. Using a commercial enzyme linked immunosorbent assay (ELISA) kit, serum TPS was determined in 361 healthy children. Median (M) TPS was found to be 107 U/l at birth (n = 124). By the end of the first week, the value rose to M = 150 U/l (n = 68) and then continuously decreased with age (1 week-1 year, n = 45, M = 88 U/l; 1-7 years, n = 75, M = 51 U/l) until reaching the adult level (8-18 years, n = 49, M = 34 U/l). Additionally, the serum TPS values of 45 mothers right after delivery (M = 161 U/l) were assessed, and there was no correlation to the marker levels determined in the cord blood of their children. The age-dependent distribution of serum TPS in healthy children must be taken into account in the clinical application of this tumor marker.

Oncogenic regulation and function of keratins 8 and 18

Keratin 8 (K8) and keratin 18 (K18) are the most common and characteristic members of the large intermediate filament gene family expressed in 'simple' or single layer epithelial tissues of the body. Their persistent expression in tumor cells derived from these epithelia has led to the wide spread use of keratin monoclonal antibodies as aids in the detection and identification of carcinomas. Oncogenes which activate ras signal transduction pathways stimulate expression of the K18 gene through transcription factors including members of the AP-1 (jun and fos) and ETS families. The persistent expression of K8 and K18 may reflect the integrated transcriptional activation of such transcription factors and, in the cases of ectopic expression, an escape from the suppressive epigenetic mechanisms of DNA methylation and chromatin condensation. Comparison of the mechanisms of transcriptional control of K18 expression with expression patterns documented in both normal and pathological conditions leads to the proposal that persistent K8 and K18 expression is a reflection of the action of multiple different oncogenes converging on the nucleus through a limited number of transcription factors to then influence the expression of a large number of genes including these keratins. Furthermore, correlation of various tumor cell characteristics including invasive behavior and drug sensitivity with K8 and K18 expression has stimulated consideration of the possible functions of these proteins in both normal development and in tumorigenesis. Recent developments in the analysis of the functions of these intermediate filament proteins provide new insights into diverse functions influenced by K8 and K18.

Molecular characterization of a tissue-polypeptide-specific-antigen epitope and its relationship to human cytokeratin 18

Tissue-polypeptide-specific antigen (TPS) from the human colon adenocarcinoma cell line WiDr was purified using the monoclonal antibody M3 as a probe. Upon SDS/polyacrylamide gradient gel electrophoresis, several TPS-positive bands were detected (corresponding to 13 kDa, 22 kDa and a doublet at 42 kDa). The 13-kDa moiety was purified about 30,000-fold by a 5-step protocol. The electro-phoretically homogeneous component was obtained in a 7% yield of the total TPS activity of the crude extract. N-terminal sequence analysis showed the presence of an N-terminally truncated molecule and identified the 13-kDa TPS component as a fragment of human cytokeratin 18, with a major from starting at position 284 of the parent molecule. Laser-desorption mass spectrometry showed the presence of one major component with a molecular mass corresponding to a C-terminal end close to position 396 (which gives 12776 Da for the form with non-truncated N-terminus). The M3 antibody was also used to screen a human prostate cDNA lambda gt11 library. Four identical phage clones were detected, each producing a fusion protein with beta-galactosidase and the M3-positive component. PCR amplification showed the presence of an approximately 1200-bp insert, and sequence analysis revealed it to contain a 996-nucleotide fragment corresponding to residues 103-429 of human cytokeratin 18 (plus a non-coding human desmin artifact fragment). Smaller fragments, engineered by PCR and expressed as fusion proteins using the pET3xc vector in Escherichia coli, showed that the M3 epitope is localized to cytokeratin 18, residues 322-340. Two other TPS-active monoclonal antibodies were localized to cytokeratin 18 with similar techniques, ascribing an epitope (to M21) to residues 414-429 and another (to M24) to residues 139-297. Combined, the results demonstrate that TPS reactivity is derived from specific epitopes of human cytokeratin 18.

Differential responsiveness of proliferation and cytokeratin release to stripped serum and oestrogen in the human breast cancer cell line, MCF-7

In vitro research into hormone sensitivity and the relation to proliferation of cytokeratin release from cancer cells is scarce. Therefore, we examined the stimulation of proliferation and the release of cytokeratins in a breast cancer cell culture model. Cell growth was stimulated by 17 beta-oestradiol (10(-11) M), stripped serum (10%) and by the two together. Cytokeratin release was stimulated only by stripped serum, oestradiol having no effect. After long incubation periods (> 12 h), cytokeratin release also commenced in the control and oestradiol treatments. Release rate versus time analysis suggested that there are two different release processes. Cytokeratin release was first stimulated at a stripped serum concentration approximately 100 times lower than that which initiated proliferation. Pharmacological alteration of proliferation with cordyceptin resulted in growth changes without alterations in cytokeratin release. We conclude that cytokeratin release in these cells is unrelated to proliferation, independent of oestrogen action and probably in some way related to growth factor receptor function.

Analytical requirements and standardization of CA 15-3

The CA 15-3 assay could play, probably in combination with cytokeratin markers, a role in the detection of early recurrence and in monitoring therapy in metastatic breast cancer patients. The CA 15-3 assay is, however, not useful for early detection of breast cancer and has no prognostic significance. The analyte is not clearly defined and a primary reference material cannot be synthesized. A reference measurement procedure is not available and many commercial assays use the original Centocor IRMA as such. The comparability of different CA 15-3 assays is not sufficient according to the results of EQAS. The general recommendations of analytical requirements for tumour marker determinations specified by the working group "Quality Control and Standardization" (Hamburger Symposia on Tumour Markers) includes intra-assay and inter-assay precision, drift, carry-over, dilution effect and high-dose hook effect. From a medical point of view reference limits should be established. Specificity/sensitivity profiles should preferentially be represented by ROCcurves. Confounding factors should be analyzed. To improve the clinical value of CA 15-3, the following needs for improvement have been identified: > Standardization of response criteria during treatment; > Definition of significant increase at recurrence; > Investigation of the biological variance during follow-up; > Definition of the analyte; > Preparation of reference material; > Development of an accepted reference method; > Integration of different international activities and > Optimizing decision-making criteria and clinical application.