Cytokeratins and Tissue Polypeptide Antigen

Biosensors for Cancer Biomarkers Based on Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNs) exhibit highly beneficial characteristics for devising efficient biosensors for different analytes. Their unique properties, such as capabilities for stable covalent binding to recognition groups (e.g., antibodies or aptamers) and sensing surfaces, open a plethora of opportunities for biosensor construction. In addition, their structured porosity offers capabilities for entrapping signaling molecules (dyes or electroactive species), which could be released efficiently in response to a desired analyte for effective optical or electrochemical detection. This work offers an overview of recent research studies (in the last five years) that contain MSNs in their optical and electrochemical sensing platforms for the detection of cancer biomarkers, classified by cancer type. In addition, this study provides an overview of cancer biomarkers, as well as electrochemical and optical detection methods in general.

Effects of jasplakinolide on cytotoxicity, cytoskeleton and apoptosis in two different colon cancer cell lines treated with m-THPC-PDT

Colorectal cancer (CRC) is a common malignant tumor, and metastasis is one of the most important challenges in the treatment of CRC. Photodynamic therapy (PDT) is a novel and non-invasive treatment that influence cytoskeleton and to reduce cancer metastases. In addition, cytoskeleton is related to cancer metastases. Two isogenic colorectal cancer cell lines SW480 and SW620 were used in the present study, we found that m-THPC mediated PDT changed the cytotoxicity, apoptosis and cytoskeleton in both cell lines. Interestingly, the expression of intermediate filaments protein cytokeratin18 were different in the two cell lines. In order to further confirm the relationship between cytoskeleton and cell migration, we combined with microfilament stabilizer jasplakinolide (JASP) to observe the effects of microfilaments on cell migration, cytotoxicity and apoptosis. Taken together, these findings suggest that m-THPC-PDT could induce cytoplasmic cytoskeleton destruction in both types of cells, especially on microfilaments and microtubules. Moreover, in SW480 cells, microtubules may participate in the apoptosis process induced by m-THPC-PDT, while microfilaments may participate in the process of m-THPC-PDT inhibiting cell migration. But in SW620 cells, only microfilaments may be involved in m-THPC-PDT induced apoptosis and inhibition of cell migration.

Detection of Cytokeratin 19 mRNA and CYFRA 21–1 (Cytokeratin 19 Fragments) in Blood of Tunisian Women with Breast Cancer

Cytokeratin 19 (CK19) is an acidic protein of 40 kDa that is part of the cytoskeleton of epithelial cells. It is highly expressed by all epithelial cells and represents a useful indicator of epithelial differentiation. The soluble fragment of CK19 (CYFRA 21–1) can be a useful circulating tumor marker and can be detected in the serum of cancer patients. The development of metastasis in patients with cancer of epithelial origin is due to the migration of tumor cells from the original tumor to distant organs. In order to detect micrometastasis in patients with breast cancer, we evaluated and compared CK19 gene expression using RT-PCR in blood samples collected from 80 healthy women and 80 patients with localized or metastatic breast cancer. The concentration of the soluble CK19 fragment CYFRA 21–1 was measured in serum of all study subjects by radioimmunoassay employing specific monoclonal antibodies. The relationship between the expression of this molecular marker and clinical stage, tumor differentiation and CK19 mRNA transcripts was investigated. We found that CK19 mRNA expression in blood (as a direct index of the presence of circulating tumor cells) was not correlated with CYFRA 21–1.

Comparative morphological evaluation of domestic animal cornea

OBJECTIVE

This study described corneal morphology in different domestic animals using histological and immunohistochemical methods. Specifically, we evaluated the species-specific distribution pattern of cytokeratins (CKs) and aquaporins (AQPs) to assess their contribution to the strength and transparency of the cornea, respectively.

PROCEDURES

Corneal sections (2 μm thick) were obtained from 28 pigs, 11 cows, two goats, six horses, four dogs, and five cats and stained with hematoxylin-eosin and periodic acid-Schiff (PAS) reaction. Immunohistochemistry was also performed using CK1 to 3 and AQP1 and 5 antibodies.

RESULTS

Domestic animal corneas were composed of corneal epithelium, stroma, Descemet's membrane, and corneal endothelium. Bowman's layer was not detected using the PAS reaction. The three-layered epithelium was thinnest in carnivores and thickest in equines and bovines. CKs were demonstrated immunohistochemically in all species examined, especially in the most superficial layer of the corneal epithelium. CKs were more widely distributed in canine and feline corneal epithelial cell layers compared to other species. The corneal monolayer endothelium was immunostained with AQP1 in all species examined, and it was also present in stromal keratocytes in a species-specific manner. In contrast, AQP5 was exclusively localized to the corneal epithelium. Epithelial staining patterns varied markedly between species, and the widest distribution of AQP5 was demonstrated in feline epithelial cell layers.

CONCLUSIONS

Differences in the distribution of CKs and AQPs in various species suggest species differences in the maintenance of structural integrity and fluid balance.

The expression of TTF-1 and Napsin A in early-stage lung adenocarcinoma correlates with the results of surgical treatment

Non-small cell lung cancer (NSCLC) accounts for 80 % of lung cancers, and lung adenocarcinoma (ADC) is one of the main types of NSCLC. Although there are several studies on the relationship between lung ADC immunohistochemical diagnostic markers (thyroid transcription factor 1 (TTF-1) and Napsin A) and survival, some aspects of those studies could be improved. We examined the significance of the commonly used lung ADC diagnostic markers, including TTF-1, Napsin A, and CK7, in the prognosis of early-stage lung ADC. One hundred and nineteen cases of early-stage lung ADC (N0) were selected from the prospective database of lung cancer (Jan 2000 to Dec 2009). The expression levels of TTF-1, Napsin A, and CK7 in inventoried specimens were analyzed using tissue microarray (TMA) and immunohistochemical (IHC) analysis, and the effect of the expression level of each marker on patients' survival was examined. The diagnostic sensitivity and specificity of each marker for lung ADC were as follows: TTF-1, 87.0 and 90.1 %; Napsin A, 72.2 and 90.4 %; and CK7, 94.6 and 76.0 %, respectively. Patients with high expression levels of TTF-1 and Napsin A, and high co-expression levels of TTF-1/Napsin A had better survival rates than those with low levels of expression (P < 0.05). The expression levels of CK7 were not related to patients' survival. Multivariate analysis showed that the expression levels of Napsin A and TTF-1/Napsin A are independent prognostic factors for survival. The IHC detection of TTF-1 and Napsin A in specimens should be routinely performed in postoperative early-stage lung ADC patients. Its significance lies not only in the differential diagnosis, but also in determining the prognosis.

Expression of p63 and CK5/6 in early-stage lung squamous cell carcinoma is not only an early diagnostic indicator but also correlates with a good prognosis

Background

Non-small cell lung cancer (NSCLC) accounts for 80% of lung cancers, and lung squamous cell carcinoma (SQCC) is one of the main types. Advances in the treatment of lung SQCC are lacking when compared to lung adenocarcinoma. The main treatment for early-stage SQCC is surgery. However, factors affecting the efficacy of surgical treatments for early-stage lung SQCC remain unclear. In this study, we examined the significance of commonly used lung SQCC diagnostic markers p63, p40, and cytokeratin (CK)5/6 in prognosis.

Methods

Seventy-six cases of early-stage lung SQCC (N₀) were obtained from our lung cancer database (January 2000 to December 2009). Tissue microarray and immunohistochemical (IHC) staining were used to detect the expression of p63, p40, and CK5/6. The effect of the expression level of each marker on patients' survival was examined.

Results

Sensitivity and specificity of each marker for detecting lung SQCC was 87.0% and 81.0% for p63, 75.9% and 97.9% for p40, and 78.9% and 97.7% for CK5/6. Survival rates of patients with high expression levels of p63 or CK5/6 or both were higher than in patients with low expression levels (P < 0.05). Expression levels of p40 had no effect on survival (P > 0.05). Multivariate analysis showed that high levels of p63 expression p63+CK5/6 co-expression were independent prognostic factors for good survival.

Conclusion

IHC staining detection of p63 and CK5/6 in specimens should be routinely performed in postoperative early-stage lung SQCC patients. Its significance lies not only in differential diagnosis, but also in determining prognosis.

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.

A sandwich-type immunosensor using Pd-Pt nanocrystals as labels for sensitive detection of human tissue polypeptide antigen

A sandwich-type immunosensor was developed for the detection of human tissue polypeptide antigen (hTPA). In this work, a graphene sheet (GS) was synthesized to modify the surface of a glassy carbon electrode (GCE), and Pd-Pt bimetallic nanocrystals were used as secondary-antibody (Ab2) labels for the fabrication of the immunosensor. The amperometric response of the immunosensor for catalyzing hydrogen peroxide (H2O2) was recorded. And electrochemical impedance spectroscopy was used to characterize the fabrication process of the immunosensor. The anti-human tissue polypeptide antigen primary antibody (Ab1) was immobilized onto the GS modified GCE via cross-linking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS). With Ab1 immobilized onto the GS modified GCE and Ab2 linked on Pd-Pt bimetallic nanocrystals, the immunosensor demonstrated a wide linear range (0.0050-15 ng ml(-1)), a low detection limit (1.2 pg ml(-1)), good reproducibility, good selectivity and acceptable stability. This design strategy may provide many potential applications in the detection of other cancer biomarkers.

Cytokeratin-19 as a biomarker in urine and in serum for the diagnosis of endometriosis--a prospective study

Endometriosis compromises the quality of life of countless women worldwide and is a leading cause of disability. Clinical symptoms of endometriosis can be very heterogeneous leading to a long interval between onset of symptoms and surgical diagnosis. A noninvasive, rapid diagnostic test is urgently needed. In this prospective study, we evaluated the usefulness of Cytokeratin-19 (CK19) as a biomarker for the diagnosis of endometriosis through urine and serum ELISA. 76 reproductive-aged women undergoing laparoscopy for benign conditions were included to this study and divided into two groups by the presence (n = 44) or absence (n = 32) of endometriosis. There was no statistically significant correlation between the concentration of CK19 in urine (p = 0.51) or in serum (p = 0.77) and the diagnosis of endometriosis. Assigning the samples to the proliferative or secretory cycle stage did not sufficiently lower the p values. In this study, the promising data reported in the recent literature about CK19 serving as a sufficient biomarker for endometriosis could not be verified when tested in a larger sample size. Further studies are warranted to explore the usefulness of CK19 in the diagnosis of endometriosis.

Serum markers in small cell lung cancer: opportunities for improvement

Lung cancer is one of the leading causes of death from malignancy worldwide. In particular small cell lung cancers, which comprise about 15-20% of all lung cancers, are extremely aggressive and cure rates are extremely low. Therefore, new treatment modalities are needed and detection at an early stage of disease, as well as adequate monitoring of treatment response is essential in order to improve outcome. In this respect, the use of non-invasive tools for screening and monitoring has gained increasing interest and the clinical applicability of reliable, tumor-related substances that can be detected as tumor markers in easily accessible body fluids is subject of intense investigation. Some of these indicators, such as high LDH levels in serum as a reflection of the disease, have been in use for a long time as a general tumor marker. To allow for improved monitoring of the efficacy of new therapeutic modalities and for accurate subtyping, there is a strong need for specific and sensitive markers that are more directly related to the biology and behavior of small cell lung cancer. In this review the current status of these potential markers, like CEA, NSE, ProGRP, CK-BB, SCC, CgA, NCAM and several cytokeratins will be critically analyzed with respect to their performance in blood based assays. Based on known cleavage sites for cytoplasmic and extracellular proteases, a prediction of stable fragments can be obtained and used for optimal test design. Furthermore, insight into the synthesis of specific splice variants and neo-epitopes resulting from protein modification and cleavage, offers further opportunities for improvement of tumor assays. Finally, we discuss the possibility that detection of SCLC related autoantibodies in paraneoplastic disease can be used as a very early indicator of SCLC.

Cytokeratins in hepatitis

Experimental and clinical evidence suggests that cytokeratins (CK), among other physiological functions, are expressed in hepatocytes and can be released in the bloodstream after acute or chronic inflammatory liver injury. Interest in CK in viral and nonviral hepatitis has been rapidly increasing during the last years, especially as they have been proposed as circulating biomarkers of hepatocyte necrosis and apoptosis. In the present review, we sought to summarize and discuss the alterations in circulating CK levels in different form viral and nonviral hepatitis, as well as their potential relation with liver histology. Understanding the mechanisms of hepatitis impact on CK and vice versa is a promising area of research that will positively enhance our understanding of the complexity of acute and chronic inflammatory liver injury.

Utilization of cytokeratin-based biomarkers for pharmacodynamic studies

Cytokeratin (CK)18 is a useful serum biomarker for the determination of cell death of epithelial-derived tumors (carcinomas). ELISAs are available for caspase-cleaved CK18 (M30) released from apoptotic cells, or total CK18 (M65) released by cells undergoing cell death by any cause. These assays have been demonstrated to have prognostic or predictive utility in various types of carcinomas. Encouraging data have been reported by different investigators with regard to the potential use of CK18 as a serum efficacy biomarker for monitoring therapy efficiency in carcinoma patients. The ratio of caspase-cleaved to total CK18 can be determined conveniently in serum or plasma using commercially available ELISA kits (M30-Apoptosense and M65 ELISA, Peviva AB, Bromma, Sweden). M30:M65 ratios potentially provide information as to whether tumor cells undergo apoptosis or necrosis. However, as discussed in this review, M30:M65 ratios should be interpreted with caution and, preferably, only be applied to samples that contain significant levels of CK18. We conclude that M30 and M65 biomarkers provide both quantitative and qualitative information on carcinoma cell death.

National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines for Use of Tumor Markers in Testicular, Prostate, Colorectal, Breast, and Ovarian Cancers

Background: Updated National Academy of Clinical Biochemistry (NACB) Laboratory Medicine Practice Guidelines for the use of tumor markers in the clinic have been developed.

Methods: Published reports relevant to use of tumor markers for 5 cancer sites—testicular, prostate, colorectal, breast, and ovarian—were critically reviewed.

Results: For testicular cancer, α-fetoprotein, human chorionic gonadotropin, and lactate dehydrogenase are recommended for diagnosis/case finding, staging, prognosis determination, recurrence detection, and therapy monitoring. α-Fetoprotein is also recommended for differential diagnosis of nonseminomatous and seminomatous germ cell tumors. Prostate-specific antigen (PSA) is not recommended for prostate cancer screening, but may be used for detecting disease recurrence and monitoring therapy. Free PSA measurement data are useful for distinguishing malignant from benign prostatic disease when total PSA is &lt;10 μg/L. In colorectal cancer, carcinoembryonic antigen is recommended (with some caveats) for prognosis determination, postoperative surveillance, and therapy monitoring in advanced disease. Fecal occult blood testing may be used for screening asymptomatic adults 50 years or older. For breast cancer, estrogen and progesterone receptors are mandatory for predicting response to hormone therapy, human epidermal growth factor receptor-2 measurement is mandatory for predicting response to trastuzumab, and urokinase plasminogen activator/plasminogen activator inhibitor 1 may be used for determining prognosis in lymph node–negative patients. CA15-3/BR27–29 or carcinoembryonic antigen may be used for therapy monitoring in advanced disease. CA125 is recommended (with transvaginal ultrasound) for early detection of ovarian cancer in women at high risk for this disease. CA125 is also recommended for differential diagnosis of suspicious pelvic masses in postmenopausal women, as well as for detection of recurrence, monitoring of therapy, and determination of prognosis in women with ovarian cancer.

Conclusions: Implementation of these recommendations should encourage optimal use of tumor markers.

Assessment of individual lung cancer risk by the proteomic analysis of exhaled breath condensate

BACKGROUND

Lung cancer is one of the leading causes of cancer-related deaths. Several diagnostic strategies are available but these are frequently ineffective, either because of their cost and organizational difficulty or because of the involvement of high radiations. As recent data from spiral computerized axial tomography have shown limited sensitivity and limited impact on cancer-related fatality, several options have been proposed in order to identify biological fluid-based biomarkers.

OBJECTIVE

Evaluating whether proteomic analysis of alveolar fluid obtained in the form of exhaled breath condensate (EBC) can be valuable for detecting and effectively diagnosing lung cancer.

METHODS

Careful review of recently published papers on proteomic EBC analysis, together with experience in the authors' laboratory, allows the discussion of benefits, pitfalls and possible future development of this approach.

RESULTS/CONCLUSIONS

The rapid advancements of proteomics are expected to validate EBC protein(s) as lung pathology biomarker(s). Accessibility of an early marker of lung cancer will be a great advantage for potentially early treatment by surgical procedures with limited tissue removal, possibly preceding metastasis development.

Biomarker method validation in anticancer drug development

Over recent years the role of biomarkers in anticancer drug development has expanded across a spectrum of applications ranging from research tool during early discovery to surrogate endpoint in the clinic. However, in Europe when biomarker measurements are performed on samples collected from subjects entered into clinical trials of new investigational agents, laboratories conducting these analyses become subject to the Clinical Trials Regulations. While these regulations are not specific in their requirements of research laboratories, quality assurance and in particular assay validation are essential. This review, therefore, focuses on a discussion of current thinking in biomarker assay validation. Five categories define the majority of biomarker assays from 'absolute quantitation' to 'categorical'. Validation must therefore take account of both the position of the biomarker in the spectrum towards clinical end point and the level of quantitation inherent in the methodology. Biomarker assay validation should be performed ideally in stages on 'a fit for purpose' basis avoiding unnecessarily dogmatic adherence to rigid guidelines but with careful monitoring of progress at the end of each stage. These principles are illustrated with two specific examples: (a) absolute quantitation of protein biomarkers by mass spectrometry and (b) the M30 and M65 ELISA assays as surrogate end points of cell death.

Cytokeratin Markers Come of Age

Cytokeratins have been extensively used as serum tumour markers for monitoring of disease progression in cancer patients. The source of cytokeratins in the circulation as well as the mechanisms of release from cells have long been unclear. Recent evidence suggests that cytokeratins present in the circulation of cancer patients are released from apoptotic or necrotic tumour cells. CK18 is cleaved by caspases during apoptosis and a monoclonal antibody (M30) specific to caspase-cleaved forms is available. The molecular form of CK18 released from cells (caspase-cleaved or not) can conveniently be determined by immunoassays (M30-Apoptosense and M65 ELISA assays; Peviva AB, Bromma, Sweden) to determine cell death mode--apoptosis or necrosis. Recent studies where these assays were used to evaluate the response to cytotoxic anticancer drugs using cancer patient serum have been encouraging. CK18 is attracting considerable interest as a response biomarker during clinical trials of anticancer drugs. Properties such as excellent antigen stability and the epithelial specificity of cytokeratins contribute to make this biomarker attractive.

Method validation and preliminary qualification of pharmacodynamic biomarkers employed to evaluate the clinical efficacy of an antisense compound (AEG35156) targeted to the X-linked inhibitor of apoptosis protein XIAP

Data are presented on pharmacodynamic (PD) method validation and preliminary clinical qualification of three PD biomarker assays. M65 Elisa, which quantitates different forms of circulating cytokeratin 18 (CK18) as putative surrogate markers of both apoptotic and nonapoptotic tumour cell death, was shown to be highly reproducible: calibration curve linearity r2 = 0.996, mean accuracy > 91% and mean precision < 3%, n = 27. Employing recombinant (r) CK18 and caspase cleaved CK18 (CK18 Asp396 neo-epitope) as external standards, kit to kit reproducibly was < 6% (n = 19). rCK18 was stable in plasma for 4 months at -20 degrees C and -80 degrees C, for 4 weeks at 4 degrees C and had a half-life of 2.3 days at 37 degrees C. Cytokeratin 18 Asp396 NE, the M30 Apoptosense Elisa assay antigen, was stable in plasma for 6 months at -20 degrees C and -80 degrees C, for 3 months at 4 degrees C, while its half-life at 37 degrees C was 3.8 days. Within-day variations in endogenous plasma concentrations of the M30 and M65 antigens were assessed in two predose blood samples collected from a cohort of 15 ovarian cancer patients receiving carboplatin chemotherapy and were shown to be no greater than the variability associated with methods themselves. Between-day fluctuations in circulating levels of the M30 and M65 antigens and in XIAP mRNA levels measured in peripheral blood mononuclear cells by quantitative (q) RT-PCR were evaluated in two predose blood samples collected with a 5- to 7-day gap from 23 patients with advanced cancer enrolled in a phase I trial. The mean variation between the two pretreatment values ranged from 13 to 14 to 25%, respectively, for M65, M30 and qRT-PCR. These data suggest that the M30 and M65 Elisa's and qRT-PCR as PD biomarker assays have favourable performance characteristics for further investigation in clinical trials of anticancer agents which induce tumour apoptosis/necrosis or knockdown of the anti-apoptotic protein XIAP.

Rapid diagnosis and follow up of bladder cancer patients using urinary high molecular weight cytokeratins

We have developed an office-based dot-EIA for the detection of a urinary high molecular weight cytokeratin (CK). Immunohistochemical staining and western blot based on CK1K10 monoclonal antibody were used to identify the CK. Urine of 192 patients with different types, grades, and stages of bladder tumor and 72 controls were evaluated using dot-EIA. An intense and diffuse cytoplasmic reaction was shown in bladder squamous cell carcinoma. The target epitope was identified in urine at 65, 56, and 40-kDa. The CK purified from urine showed single polypeptide at 65-kDa using SDS-PAGE and single peak at 7.4 min using capillary zone electrophoresis. The dot-EIA detected the CK with high sensitivity (97%) and specificity (94%). The CK was not detected in urine of bladder cancer patients showing response to radiotherapy. The sensitive and specific office-based detection of urinary cytokeratin would be helpful in rapid diagnosis and follow up of bladder carcinoma.

Serum CYFRA 21-1 in patients with invasive bladder cancer and its relevance as a tumor marker during chemotherapy

PURPOSE

Previous studies have shown that serum levels of the degradation products of cytokeratins could be used as surrogate markers in the diagnosis and followup of patients with solid tumors, including tumors of the bladder.

MATERIALS AND METHODS

The soluble cytokeratin 19 fragment CYFRA 21-1 was measured by solid phase radioimmunoassay in the serum of 142 patients with invasive transitional cell cancer of the bladder. Of the patients 56 had clinical stage I to III locally confined disease (T1-4aN0M0) and 86 had stage IV metastatic disease with lymph node and/or distant metastases. A control group consisted of 33 healthy volunteers. In a subgroup of 49 patients with metastatic disease receiving combined platinum based chemotherapy serum CYFRA 21-1 was determined prior to the initiation of therapy and after the documentation of response.

RESULTS

Abnormal CYFRA 21-1 was observed in 7% of patients with locally invasive disease and in 66% of those with metastatic disease (p < 0.0001). There was no correlation of CYFRA 21-1 with tumor differentiation. Patients with abnormal CYFRA 21-1 showed statistically significant worse median overall survival. Moreover, in the subgroup of patients with metastatic disease receiving chemotherapy CYFRA 21-1 levels correlated with the response to treatment.

CONCLUSIONS

Patients with transitional cell cancer of the bladder with evidence of distant metastases showed a significant increase in serum CYFRA 21-1. During chemotherapy CYFRA 21-1 appears to be a potentially sensitive and useful indicator for monitoring treatment response.

Newly developed assay measuring cytokeratins 8, 18 and 19 in serum is correlated to survival and tumor volume in patients with esophageal carcinoma

Esophageal carcinoma is the seventh most common cause of cancer-related death in the Western world. In Sweden, approximately 400 new esophageal carcinomas are diagnosed yearly. Cytokeratins (CK) are specific for epithelial cells and the expression profile usually remains unchanged even when the epithelium undergoes malignant transformation. In the present study, MonoTotal, a newly developed RIA-assay detecting circulating CK 8, 18 and 19 fragments, was investigated in sera from patients with esophageal carcinoma. Serum samples from 40 patients with esophageal carcinoma were collected. The median value of circulating CK 8, 18 and 19 measured with MonoTotal was 378 U/L (range 53-6843) and with regard to the defined cut-off (< 75 U/L), 39/40 (98%) patients were shown to have elevated levels of circulating CK 8, 18 and 19. Patients with localized disease had a median value of circulating CK 8, 18 and 19 of 305 U/L (mean: 500 U/L), whereas the corresponding value for metastatic disease was 771 U/L (mean: 1506 U/L). This difference was statistically significant (P = 0.016). Circulating CK 8, 18 and 19, according to cut-off, were not associated with survival in univariate analysis (P = 0.34). However, continuous values of circulating levels of CK 8, 18 and 19 were associated with survival (P = 0.000083) in univariate as well as in the multivariate analysis (P = 0.03). In conclusion, circulating CK 8, 18 and 19 correlates with increased tumor burden and might, in conjunction with other clinical parameters, aid the clinician in estimating the prognosis of the individual patient.

Androgen receptor is targeted to distinct subcellular compartments in response to different therapeutic antiandrogens

PURPOSE

Antiandrogens are routinely used in the treatment of prostate cancer. Although they are known to prevent activation of the androgen receptor (AR), little is known about the mechanisms involved. This report represents the first study of the localization of wild-type AR following expression at physiologic relevant levels in prostate cells and treatment with androgen and antiandrogens.

EXPERIMENTAL DESIGN

We have characterized a cellular model for prostate cancer using in situ cellular fractionation, proteomics, and confocal microscopy and investigated the effect of antiandrogens in clinical use on the subcellular localization of the AR.

RESULTS

Different antiandrogens have diverse effects on the subcellular localization of the AR. Treatment with androgen results in translocation from the cytoplasm to the nucleoplasm, whereas the antiandrogens hydroxyflutamide and bicalutamide lead to reversible association with the nuclear matrix. In contrast, treatment with the antiandrogen cyproterone acetate results in AR association with cytoplasmic membranes and irreversible retention within the cytoplasm. In addition, we demonstrate that AR translocation requires ATP and the cytoskeleton, regardless of ligand.

CONCLUSIONS

These results reveal that not all antiandrogens work via the same mechanism and suggest that an informed sequential treatment regime may benefit prostate cancer patients. The observed subnuclear and subcytoplasmic associations of the AR suggest new areas of study to investigate the role of the AR in the response and resistance of prostate cancer to antiandrogen therapy.

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.

Effect of Opium Smoking on Concentrations of Carcinoembryonic Antigen and Tissue Polypeptide Antigen

Previous studies have related opium and its pyrolysates to the risk of developing certain cancers. The aim of this work was to evaluate the clinical usefulness of determining carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) levels in habitual opium smokers. Serum CEA concentrations were measured in 128 opium smokers and in 44 controls of cigarette only smokers and 47 normal non-smokers by an EIA-based assay. TPA levels were also determined in serum and urine of a subgroup in the study population. The results indicated that serum CEA concentrations are higher in opium smokers than in healthy tobacco smokers (p=0.004) and non-smokers (p=0.001). The amount of opium used correlated with the serum CEA level (r=0.276, p<0.0001). The mean urine and serum TPA levels of the opium-addicted population were also higher than that of the non-smoking control group, but the differences were not statistically significant. We conclude that opium smoking is associated with elevated serum CEA levels. Therefore, for management of opium users with neoplastic diseases, increased levels of serum CEA should be viewed with caution to avoid misdiagnosis.

Expression of cytokeratin 18 during pre- and post-natal porcine lung development

The expression pattern of the intermediate filament protein cytokeratin 18 (CK 18) is described during pre- and post-natal development of the porcine lung using a monoclonal antibody against human CK 18. Lungs from 16 foetuses in pseudoglandular, canalicular, saccular and alveolar stages of lung development and lungs from 12 pigs ranging in age from birth to 49 days after birth were studied by immunohistochemistry. In the early pseudoglandular stage of development (day 70 of gestation) all the columnar epithelial cells lining the tubular endbuds strongly expressed CK 18 predominantly in the apical cell compartment. A modest staining was found in the more cuboidal cells of the canalicular stage (day 80 of gestation) where the labelling occurred as a distinct positive rim at the apical cell membrane in most of the cells lining the canaliculi. In 96- and 100-day-old foetuses, parts of the gas exchanging area were formed as terminal sacs by extreme attenuation of the epithelium. In this stage, CK 18 was clearly detectable in the flat type I as well as in the cuboidal type II alveolar epithelial cells. A marked change of the CK 18 expression pattern occurred during formation of the alveoli by septal outgrowth and maturation of the epithelium in 105- and 111-day-old foetuses. Differentiated type I cells no longer expressed CK 18, whereas type II cells were still labelled. Moreover, a specific change in the subcellular distribution pattern from the luminal periphery in immature porcine type II cells to a cytoplasmic localization in differentiated type II cells could be observed. Our investigation additionally demonstrated that the epithelium of bronchi, bronchioli and terminal bronchioli expressed CK 18 in all pre- and post-natal developmental stages. From the 96 days of gestation onwards the epithelial cells of developing bronchial glands were also labelled. Our results clearly show that during porcine lung development profound changes in the cellular expression pattern of CK 18 occur and that CK 18 can be regarded as a selective marker for differentiated porcine alveolar type II cells from the 105th day of gestation onwards. We also assume that the intermediate filament CK 18 could be of significance in the maturation process of the type II alveolar cells.

Diagnostic value of cytokeratin-18 as a tumor marker in bladder cancer

OBJECTIVES

The aim of the study was to compare serum levels of cytokeratin-18 of patients with bladder cancer with those of the healthy controls, and to investigate the relation between cytokeratin level and the tumor stage.

DESIGN AND METHODS

Serum cytokeratin-18 levels of 38 patients with bladder cancer and of 25 healthy people were determined. Tumor stage was T(1) in 12 patients, T(2) in 9 patients, T(3) in 10 patients and T(4) in 7 patients. The serum cytokeratin-18 levels in these cases were analyzed with respect to the stage of the tumor.

RESULTS

Cytokeratin-18 level in the patient group was found to be significantly higher than that of the control group (p < 0.010) when the groups were totally compared. However, when the levels in patients with different tumor stages were compared with that of the controls, the difference was not significant in patients with stage 1 and 2 tumors (p > 0.05). Regarding the cut off value as 4.0 ng/mL, sensitivity and specificity for serum cytokeratin-18 were found to be 53% and 72% respectively. When sensitivity was calculated with respect to tumor stages, it was 8% for T(1,) 33% for T(2,) 90% for T(3) and 100% for T(4.) On the other hand, considering higher stage (T(3) and T(4)) tumors only, the sensitivity was calculated as 94%, but the sensitivity for lower stage (T(1) and T(2)) tumors was 19%.

CONCLUSIONS

It is clear that serum cytokeratin-18 level increases in patients with bladder cancer. However, it can only be useful as a tumor marker in the diagnosis of T(3) and higher staged tumors. This study indicated that cytokeratin-18 does not have any diagnostic value in lower stage bladder cancers.

Serum cytokeratin fragment 21.1 (CYFRA 21.1) as tumour marker for breast cancer: comparison with carbohydrate antigen 15.3 (CA 15.3) and carcinoembryonic antigen (CEA)

Serum carbohydrate antigen 15.3 (CA 15.3) and carcinoembryonic antigen (CEA) are currently employed in clinical practice as markers for breast cancer, particularly in the follow-up and therapy monitoring. However, the American Society for Clinical Oncology (ASCO) stated in its clinical practice guidelines for the use of tumour markers in breast carcinoma that neither CA 15.3 nor CEA are recommended for routine use in screening, diagnosis and surveillance after primary treatment, or in monitoring response to treatment, because current literature data are insufficient. Cytokeratin fragment 21.1 (CYFRA 21.1) assay detects a serum fragment of cytokeratin 19 (CK19) and is employed in the diagnosis and management of lung cancer, particularly of squamous cell histotype. Breast carcinoma has been demonstrated to express CK19 fragments in the primary and metastatic lesions and CK19 mRNA is detectable in peripheral blood from patients affected by breast cancer. We measured serum markers CYFRA 21.1, CEA and CA 15.3 in the sera from 212 females affected by histologically proven breast carcinoma. Patients comprised 96 individuals with untreated primary disease (54 stage I-II, 18 stage III and 24 stage IV), 30 regional (chest-wall and/or lymph-nodes) relapsing disease and 68 metastatic (haematogenous metastases) relapsing disease. Forty-eight patients previously treated by surgery and without any evidence of disease were enrolled to evaluate the role of serum markers in the monitoring for recurrence of the disease. One hundred healthy age-matched females and 65 patients affected by benign mammary gland disease (including 38 patients with mastopathy and 27 with fibroadenoma) were enrolled as controls. Serum levels of all markers increased from controls to patients affected by breast cancer, from stage I-II to stage IV of the breast cancer and from local to advanced recurrence. The comparison of diagnostic accuracy in the detection of primary and relapsing breast cancer showed no significant differences between markers. Univariate and multivariate survival analysis showed a significant statistically prognostic value for CA 15.3 and CYFRA 21.1 but not for CEA. However, the factors N and M were confirmed to be very strong predictors of the patients' survival. Finally, CEA and CYFRA 21.1 detected less recurrences than CA 15.3. In conclusion, our data show no significant improvement in the diagnosis, prognostic evaluationand follow-up of breast cancer by CYFRA 21.1 and CEA assays compared to CA 15.3 assay. Considering the ASCO statement on tumour markers in breast cancer, the CYFRA 21.1 assay should not be employed in clinical practice.

Lung tumor markers of cytokeratin origin: an overview

Lung tumor markers fall into several categories including oncofetal proteins, structural proteins and their fragments, enzymes, membrane antigens, peptide and non-peptide hormones. Cytokeratins (CK) are well known structural proteins whose degradation gives rise to soluble fragments, measurable in the blood of patients and capable of cancer marking. Among them, Tissue Polypeptide Antigen (TPA), Tissue Polypeptide-Specific Antigen (TPS) and Cytokeratin-19-Fragments (Cyfra 21-1) are the most studied CK fragments' complexes. This article will review biological characteristics and clinical properties of these substances, emphasizing as their concentration in the peripheral blood might reflect the mass of tumor, the rate of cancer cell lysis, and other potentially unfavorable tumor characteristics. Assaying the concentration of CK fragments in the blood is an easy and effective way to assess lung cancer and monitor its clinical evolution.

Diagnostic and prognostic tumor markers in the gastrointestinal tract

The gastrointestinal tract is the most common site of malignancies of any anatomic system in the body. An early detection of primary tumors of the bowel, pancreas, liver, stomach, and esophagus is often difficult in asymptomatic patients and for this reason these tumors are often detected at a relatively advanced stage, when symptoms lead to a diagnostic evaluation. Furthermore, gastrointestinal tract tumors have an extremely variable prognosis; thus, the identification of new prognostic parameters may be useful for selecting patients to more tailored therapies. In this work, the main molecular, genetic, tissular, and circulating tumor markers proposed for diagnosis and prognosis of gastrointestinal malignancies are reviewed and discussed.

Assessment of CA 15.3, CEA and TPA concentrations during monitoring of breast cancer

The variability of the tumor markers cancer antigen (CA) 15.3, carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) during steady state concentrations and the rate of increase during progression is described. One hundred and ninety-two patients were monitored during first-line chemotherapy for metastatic breast cancer and during follow-up. Blood specimens were sampled approximately every four weeks. Steady state concentrations were registered for 77 (CA 15.3), 96 (CEA), and 127 (TPA) patients with below cutoff level values and for 28 (CA 15.3), 25 (CEA), and 11 (TPA) patients with above cutoff level values. Clinical and marker progression was registered for 75 (CA 15.3), 62 (CEA), and 57 (TPA) patients. The coefficients of total variation of steady state concentrations (comprising the intra- and interassay analytical imprecision and the within subject biological variation) were higher below (14.9% CA 15.3, 15.4% CEA, 25.9% TPA) than above cutoffs (9.6% CA 15.3,6.0% CEA, 19.9% TPA). The variability was similar for CA 15.3 and CEA but higher for TPA. During progression the rates of increase in concentrations were similar for CA 15.3 (0.0257) and CEA (0.0214) and lower than for TPA (0.0346). Our data indicate that criteria for assessment of sequential tumor marker concentrations should consider the marker in question, the steady state variability, the cutoff value, and the rate of increase during disease progression.

The effects of transurethral resection and cystoprostatectomy on dissemination of epithelial cells in the circulation of patients with bladder cancer

This study was undertaken to evaluate the risk of haematogenous dissemination of epithelial cells induced by endoscopic resection and/or cystoprostatectomy for transitional cell carcinoma of the bladder. Thirty-three patients were studied. Thirty-one had different stages and grades of bladder cancer and two patients had benign bladder conditions. Twenty-five cancer patients required transurethral resection of their bladder tumour. Of those, 20 had superficial disease (pTaG1-G2: n = 19; pT1G2: n = 1) and five had muscle invasive tumours (pT2G3: n = 2; pT3aG3: n = 1; pT4G3: n = 2). Five patients underwent radical cystoprostatectomy for muscle invasive cancers (pT2G3: n = 3; pT3bG3: n = 1; pT4G3: n = 1) and one man received chemotherapy for metastatic disease. Venous blood (10 ml) was obtained from the antecubital fossa in each patient, before and 1-2 h after completion of surgery, and prior to treatment in the metastatic patient. An indirect immunocytochemical technique was used to detect circulating epithelial cells after centrifugation on Ficoll gradient and fixation of mononuclear cells on slides, using a monoclonal antibody directed against three cytokeratins: CK8, CK18 and CK19. Circulating epithelial cells were detected only in the patient with metastatic disease. None of the other patients had evidence of epithelial circulating cells before or after surgery. The results suggest that irrespective of disease stage and grade, neither endoscopic nor open bladder surgery leads to detectable dissemination of urothelial cells in the peripheral circulation. These procedures are therefore unlikely to increase the risk of progression and metastasis in transitional cell carcinoma of the bladder.

Assessment of biological variation and analytical imprecision of CA 125, CEA, and TPA in relation to monitoring of ovarian cancer

OBJECTIVES

Changes in serial tumor marker results during monitoring of patients with ovarian cancer are due not only to deterioration or amelioration of the patient's condition, but also to preanalytical sources of variation (CPP), total random analytical error, and within-subject normal biological variation. The aim of the study was to assess (i) the analytical imprecision (CVA) and the average inherent intra- and interindividual biological variation (CVTI and CVG, respectively) for CA 125, CEA, and TPA in a group of healthy women; (ii) the significance of changes in serial results of each marker; and (iii) the index of individuality.

METHODS

The study group consisted of 31 healthy women. Sixteen blood samples from each subject were collected in four series over a period of approximately 1 year. Data analysis was based on ANOVA. The index of individuality was calculated as ((CV2A + CV2TI)/CV2G)1/2 and the critical difference for a change between two consecutive concentrations as radical2xZx(CV2P + CV2A + CV2TI)1/2 (Z = 1.65 for unidirectional and 1.96 for bidirectional changes, P </= 0.05).

RESULTS

The averages of CVTI and CVG were 35.5 and 70.6% for CA 125, 13.9 and 58.3% for CEA, and 31.4 and 62.5% for TPA, respectively. The indices of individuality were 0.5 for CA 125, 0.3 for CEA, and 0.5 for TPA. The critical differences of CA 125, CEA, and TPA were 84.6, 37.6, and 76. 3%, respectively (Z = 1.65). There were no significant differences in CA 125, CEA, and TPA concentrations between smokers and nonsmokers or in CA 125 and CEA concentrations between pre- and postmenopausal women. Postmenopausal women had higher TPA concentrations than premenopausal (P = 0.015).

CONCLUSION

CVA and CVTI contribute considerably to the variation in serial results and should, therefore, be included in the criteria for serum tumor marker assessment during monitoring of patients with ovarian cancer.

Squamous cell granulomas of the neck: histologic regression of metastatic squamous cell carcinoma following chemotherapy and/or radiotherapy

BACKGROUND

For patients with squamous cell carcinoma of the head and neck (HNSCC), persistence of cervical adenopathy following organ-preservation therapy is a strong predictor of locoregional failure. Squamous cell granulomas of the neck may represent a regressed state of metastatic HNSCC; however, relevant clinicopathologic features of this lesion including its morphologic characteristics, association with therapy, and relationship to disease progression are not well defined.

METHODS

We reviewed 866 consecutive neck dissections performed at The Johns Hopkins Hospital from 1984 to 1996. A total of eight cases showing a foreign-body giant-cell reaction to keratin in the absence of viable tumor formed the basis of this study.

RESULTS

All eight cases were from patients with stage III or IV HNSCC with concurrent neck masses. Patients were initially treated by chemotherapy (n = 1), radiotherapy (n = 1), or chemotherapy plus radiotherapy (n = 6); and all patients subsequently underwent neck dissection for persistence of their neck masses. Histologically, the neck lesions were characterized by a foreign-body giant-cell reaction to keratin and extensive scarring. None (0%) of the patients developed recurrent regional disease in the treated neck. Two (25%) of the patients had tumor recurrence at the primary site. Two (25%) of the patients developed widely metastatic disease.

CONCLUSIONS

These observations suggest that squamous cell granulomas represent histologic regression of metastatic squamous cell carcinoma in patients with HNSCC treated by chemotherapy and/or radiotherapy. Although persistent cervical adenopathy is an established risk factor for locoregional failure in this group of patients, squamous cell granulomas of the neck paradoxically may reflect enhanced regional tumor sensitivity to cytotoxic agents.

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.

Serum M3/M21 in cervical cancer patients

Cytokeratins are polypeptides which constitute a subclass of intermediate filaments in epithelial cells. The serum tumour marker M3/M21 is based on monoclonal antibodies against the epitopes M3 and M21 of cytokeratin 18. In the present study, we measured M3/M21 serum levels in 50 patients with FIGO stage IB-IIB cervical cancer and in 50 control subjects using a two-site radiometric immunoassay directed against soluble fragments of cytokeratin 18. Median serum levels of M3/M21 in patients with cervical cancer and in normal controls were 70.6 U/ml (range 0-397.7) and 6.5 U/ml (range 0-205.2), respectively (Mann-Whitney U-test, P = 0.0001). Median serum levels of M3/M21 prior to therapy and 4 weeks after therapy were 104.2 U/ml (range 24.6-397.7) and 39.3 U/ml (range 0-234.7), respectively (Mann-Whitney U-test, P = 0.004). We found a significant correlation between elevated M3/M21 serum levels and metastatic disease in pelvic lymph nodes (Mann-Whitney U-test, P = 0.002). 24 patients relapsed after complete remission. In these patients, elevated M3/M21 serum levels before the detection of relapse by computed tomography was observed in 13 cases. Considering these preliminary results, further studies with an increased number of patients are justified to clarify the prognostic value and the monitoring abilities of M3/M21 in cervical cancer patients.

The prognostic application of cytokeratin typing of nonsmall cell lung carcinoma. A retrospective study

BACKGROUND

In a previous study, the authors used a variety of anticytokeratin monoclonal antibodies to show that a large proportion of lung tumors cytologically diagnosed as squamous cell carcinoma contain cells expressing simple epithelial cytokeratins, suggesting that these tumors have their origin in adenocarcinoma. These findings raised the possibility that cytokeratin (CK) typing might have a diagnostic capacity not attainable by standard histopathology. The aim of the current study was to assess the value of CK typing for this purpose by determining the correlation between the diagnosis of lung tumors based on CK typing and the survival rate of the patients.

METHODS

Paraffin embedded tissue sections of 66 nonsmall cell lung carcinoma (NSCLC) specimens were examined. These included 18 adenocarcinomas, 32 squamous cell carcinomas, and 16 undifferentiated carcinomas, all diagnosed surgically and histopathologically, and further classified as either Stage I or II. CK typing was performed using the streptavidin-biotin-peroxidase method, employing the following anti-CK monoclonal antibodies: Ks.B.17 (which reacts with CK 18), A3-3 (which reacts with CK 13), and E5-9 (which reacts with CK 10).

RESULTS

Comparison between the 5-year survival rates (5 ysr) of patients with different NSCLC indicated that all types of Stage II tumors had a much poorer prognosis than Stage I tumors. Differences found in the 5 ysr among patients with different types of Stage I tumors were not statistically significant (adenocarcinomas, 33% 5 ysr; squamous cell carcinomas, 59% 5 ysr; undifferentiated carcinomas, 36% 5 ysr; all diagnosed by conventional histopathology). Similarly, no significant differences were noted in 5 ysr between patients with tumors stained positively or negatively with monoclonal antibodies A3-3 or E5-9 (anti-CK 13 and anti-CK 10, respectively). In contrast, highly significant differences (P = 0.002) were found in the 5 ysr between patients with Stage I tumors positively or negatively stained with monoclonal antibody Ks.B.17 (23% vs. 75% 5 ysr, respectively) regardless of the histologic types of tumors. Especially informative was a combination of immunohistochemical and histologic diagnoses, with best survival rates (87% 5 ysr) in Ks.B.17 negative tumors histologically diagnosed as Stage I squamous cell carcinomas and worst survival rates (14% 5 ysr) in Ks.B.17 positive tumors diagnosed as adenocarcinomas.

CONCLUSIONS

The current study showed that CK 18 typing of lung tumors can provide a more accurate diagnosis and therefore facilitate the planning of more suitable therapeutic approaches.

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.