Liver Cancer-Specific Isoform of Serine Protease Inhibitor Kazal for the Detection of Hepatocellular Carcinoma: Results from a Pilot Study in Patients with Dysmetabolic Liver Disease.

Reliable non-invasive biomarkers for the surveillance of patients at risk of hepatocellular carcinoma (HCC) development represent an unmet medical need. Recently, the liver-cancer-specific isoform of serine protease inhibitor Kazal (LC-SPIK) has been proposed as a valuable biomarker for the detection of HCC in patients with chronic liver disease of viral etiology. In the present study, we assessed the diagnostic accuracy of LC-SPIK, alone or in combination with standard serologic biomarkers (i.e., alpha-fetoprotein and protein induced by vitamin K absence or antagonist-II, PIVKA-II), for the detection of HCC among patients with dysmetabolic liver disease. A total of 120 patients with non-alcoholic fatty liver disease (NAFLD), including 62 patients with a diagnosis of HCC and 58 with cirrhosis but without tumor, were retrospectively analyzed. The serum levels of LC-SPIK were measured by enzyme-linked immunosorbent assay (ImCare Biotech, Doylestown, PA). The serum LC-SPIK values were significantly different between patients with HCC (24.3, 17.6−39.8 ng/mL) and those with cirrhosis but without tumor (11.7, 8.7−18.2 ng/mL) (p < 0.001). By receiver operating characteristic curve analysis, we observed an area under the curve (AUC) of 0.841 for the detection of HCC; the combination with PIVKA-II further increased the accuracy to AUC = 0.926 (cross-validation). The promising results observed in the present pilot study foster additional research to investigate the usefulness of LC-SPIK for the stratification of the risk of HCC development in patients with NAFLD and advanced liver disease.

Podocalyxin as a Prognostic Marker in Gastric Cancer.

BACKGROUND: Podocalyxin-like 1 (PODXL) is a cell-adhesion glycoprotein associated with aggressive tumor phenotype and poor prognosis in several forms of cancer. The aim of this study was to investigate PODXL expression in gastric cancer by use of two different antibodies. METHODS: By tumor-tissue microarrays and immunohistochemistry we evaluated PODXL expression in tumor specimens from 337 patients who underwent surgery for gastric adenocarcinoma at Helsinki University Hospital. We used two different antibodies: HPA2110, which is a polyclonal antibody and an in-house monoclonal antibody called HES9, to investigate the association of PODXL expression with clinicopathologic variables and patient survival. RESULTS: PODXL staining was positive by the polyclonal antibody in 153 (57.5%) cases and by the monoclonal antibody in 212 (76%). Polyclonal antibody expression was associated with intestinal cancer type (p<0.001). Monoclonal antibody staining was associated with age over 66 (p = 0.001), with intestinal cancer (p<0.001), and with small tumor size (≤ 5 cm; p = 0.024). Both antibodies were associated with high S-phase fraction (p = 0.022; p = 0.010), and high tumor proliferation index (Ki-67; p = 0.003; p = 0.001). PODXL positivity by the polyclonal antibody indicated reduced gastric-cancer-specific 5-year survival of 24.0% (95% CI 16.9-31.1), compared to 43.3% (95% CI 33.7-52.9) for patients with PODXL negativity (p = 0.001). The result remained significant in multivariable analysis (HR = 3.17; 95% CI 1.37-7.34, p = 0.007). CONCLUSION: In gastric cancer, PODXL expression by the polyclonal antibody HPA2110 is an independent marker of poor prognosis.

Expression of Stem Cell-associated Marker HES77 in Rectal Neuroendocrine Tumors.

BACKGROUND: Expression of novel stem cell-associated marker human embryonic stem cell 77 (HES77) was studied in rectal neuroendocrine tumors (NETs), which comprise 10 to 15% of gastroenteropancreatic NETs, some with metastatic potential. MATERIALS AND METHODS: WHO 2010 classification was applied, and immunohistochemical positivity for HES77 was assessed in 72 primary tumors and 6 metastases. Correlations were calculated between HES77 expression, metastasis and patient survival. RESULTS: Expression of HES77 strongly positively correlated with metastatic potential and poorer prognosis. The proliferative index determined in the metastasis did not correlate with patient survival. CONCLUSION: Novel stem cell-associated marker HES77 has a strong prognostic value in patients with rectal NETs and may be useful in selecting those who are at-risk for developing metastatic disease, and who may benefit from intensive adjuvant therapy. Proliferative index in the metastasis did not predict for outcome. Characterization of the HES77 epitope would certainly enhance the interest in the antibody.

Podocalyxin Is a Marker of Poor Prognosis in Pancreatic Ductal Adenocarcinoma.

AIM OF THE STUDY: Podocalyxin-like 1 is a transmembrane glyco-protein whose overexpression associates in many cancers with poor prognosis and unfavorable clinicopathological characteristics. Until now, its prognostic value has never been studied in pancreatic ductal adenocarcinoma (PDAC). The aim of this study was to investigate podocalyxin expression in PDAC by a novel monoclonal antibody and a commercially available polyclonal antibody. PATIENTS AND MATERIALS: With tissue microarrays and immuno-histochemistry, podocalyxin expression evaluation involved 168 PDAC patients. The associations of the podocalyxin tumor expression with clinicopathological variables were explored by Fisher's exact test and the linear-by-linear test. Survival analyses were by Kaplan-Meier analysis and the Cox proportional hazard model. RESULTS: The polyclonal antibody revealed membranous podocalyxin expression in 73 (44.0%) specimens and the monoclonal antibody was highly expressed in 36 (21.8%) cases. Membranous expression by the polyclonal antibody was associated with T classification (p=0.045) and perineural invasion (p=0.005), and high expression by the mono-clonal antibody with poor differentiation (p=0.033). High podocalyxin expression associated significantly with higher risk of death from PDAC by both the polyclonal antibody (hazard ratio (HR) = 1.62; 95% confidence interval (CI) 1.12-2.33; p=0.01) and the monoclonal antibody (HR = 2.10, 95% CI 1.38-3.20; p<0.001). The results remained significant in multivariate analysis, adjusted for age, gender, stage, lymph node ratio (≥/< 20%), and perivascular invasion (respectively as HR = 2.03; 95% CI 1.32-3.13, p=0.001; and as HR = 2.36; 95% CI 1.47-3.80, p<0.001). CONCLUSION: We found podocalyxin to be an independent factor for poor prognosis in PDAC. To our knowledge, this is the first such report of its prognostic value.

A novel stem cell associated marker identified by monoclonal antibody HESC5:3 differentiates between neoplastic lesions in follicular thyroid neoplasms.

Follicular thyroid lesions are the bane of cytopathology. Differentiation between adenoma and carcinoma is impossible, and often these neoplasms are indistinguishable even from uninodular goitre. In other cancers as well, a theory of stem cells as the origin of cancer has been discussed in thyroid carcinogenesis. We aimed to examine a novel stem cell associated marker identified by monoclonal antibody HESC5:3 in follicular lesions in an attempt to find a marker for differential diagnosis in thyroid cytopathology. HESC5:3 was raised against and is specific for undifferentiated human embryonic stem cells. The epitope of this novel antibody is to be defined. Immunohistochemical expression of HESC5:3 was examined in clinical material comprised of follicular neoplasms (83 adenomas, 43 carcinomas) and non-neoplastic lesions (41 goitrous, 22 hyperplastic, 23 normal tissue specimens). Staining differed significantly between neoplastic and non-neoplastic lesions. Nuclear staining was increased in non-neoplastic cells, whereas in neoplastic cells expression was mainly cytoplasmic. There was no difference between benign and malignant lesions, suggesting a role in early tumourigenesis. In conclusion, the HESC5:3 epitope may be of benefit as a neoplasia marker in distinguishing between uninodular goitre and neoplasia. Characterization of the epitope would increase the interest in this promising new stem cell associated marker.

Podocalyxin is a marker of poor prognosis in colorectal cancer.

BACKGROUND: Over two decades ago, a proposal was that two different colorectal cancer (CRC) entities existed, based on tumour location either proximal (right) or distal (left) of the splenic flexure. Proximal and distal tumours exhibit different clinical, epidemiological, and biological characteristics. Improvement of the prognostic evaluation of CRC requires new molecular markers. Podocalyxin-like 1 (PODXL), an anti-adhesive transmembrane sialomucin, is associated with an aggressive tumour phenotype and poor prognosis. For colorectal cancer, it has been suggested to be a marker of poor prognosis. The aim of this study was to investigate the role of PODXL in CRC by use of a novel monoclonal antibody. METHODS: In 1983-2001, 840 consecutive colorectal cancer patients were treated at Helsinki University Central Hospital, of whom 767 were successfully scored for PODXL immunohistochemical expression from tumour tissue microarrays by use of a novel monoclonal in-house antibody. Associations of PODXL expression and tumour location with other clinicopathological variables were explored by Fisher's exact-test, linear-by- linear association test, and binary logistic regression. Survival analyses were done by the Kaplan-Meier method and Cox proportional hazards model. RESULTS: PODXL protein expression was high in 44 (5.7%) specimens. High expression associated strongly with poor differentiation (p < 0.0001), advanced stage (p = 0.011), and location of the tumour in the right hemicolon (RHC) (p < 0.001). Tumours of the RHC were more poorly differentiated (p < 0.0001) and showed higher PODXL expression (p < 0.001).High PODXL expression associated significantly with higher risk for disease-specific death from CRC (hazard ratio (HR) = 2.00; 95% confidence interval (CI) 1.31-3.06, p = 0.001) and also in the subgroups of left hemicolon (LHC) cancers (HR = 2.60; 95% CI 1.45-4.66, p = 0.001) and rectal cancers (HR = 3.03; 95% CI 1.54-5.60, p = 0.001). Results remained significant in multivariable analysis (respectively, HR = 1.82; 95% CI 1.15-2.86, p = 0.01; HR = 2.59; 95% CI 1.41-4.88, p = 0.002; and HR = 2.69; 95% CI 1.30-5.54, p = 0.007). CONCLUSION: Podocalyxin was an independent factor for poor prognosis in colorectal cancer and in the subgroups of left hemicolon and rectum. This is, to our knowledge, the first evidence of such difference in PODXL expression, its function possibly being dependent upon tumour location.

A comparative study of two PODXL antibodies in 840 colorectal cancer patients.

BACKGROUND: Podocalyxin (PODXL) is a transmembrane sialomucin, whose aberrant expression and/or allelic variation associates with poor prognosis and unfavourable clinicopathological characteristics in different cancers. Membranous expression of PODXL has been suggested to be an independent marker of poor prognosis in colorectal cancer (CRC), and previously by an in-house monoclonal antibody, we showed that also cytoplasmic overexpression of PODXL predicts poor prognosis. The aim of this study was to compare two PODXL antibodies with different epitopes case-by-case in CRC patients. METHODS: Of 840 consecutively operated CRC patients from Helsinki University Central Hospital, PODXL expression by polyclonal HPA 2110 antibody was evaluated from 780. Associations of PODXL expression with clinicopathological parameters and the impact of PODXL expression on survival were assessed. Kappa-value was used to assess the comparability of the two antibodies. RESULTS: Membranous PODXL expression associated with unfavourable clinicopathological parameters and with higher risk for disease-specific death from CRC within 5 years (unadjusted hazard ratio (HR) = 1.90; 95% confidence interval (CI) (1.32-2.75); adjusted HR = 1.64; 95% CI (1.11-2.43)). The comparability of expressions by the two antibodies was low (kappa =0.219, standard error 0.060, p < 0.0001). Combination of two antibodies identified a group of patients with even worse prognosis (unadjusted HR = 6.00; 95% CI (3.27-13.0); adjusted HR = 2.14; 95% CI (1.12-4.07)). CONCLUSION: Membranous expression by the polyclonal PODXL antibody and cytoplasmic overexpression by the monocolonal PODXL antibody are both independent markers of poor prognosis, but they recognise different groups of patients, both of which have poor prognosis. The combined use of the antibodies reveals a group with an even worse prognosis. The biological reasons for the difference between antibodies warrant further studies.

Detection of human papillomavirus oncoprotein E7 in liquid-based cytology.

The selection and characterization of a set of mouse mAbs against high-risk human papillomavirus (HPV) E7 oncoprotein and the development of protocols for immunocytochemistry (ICC) are described here. A large number of antibodies raised towards HPV16 and 18 E7 were tested for high-risk specificity by ELISA using a panel of HPV E7 proteins. Antibodies detecting low-risk E7 were discarded, resulting in 38 high-risk HPV E7-specific antibodies. The corresponding epitopes were mapped using overlapping HPV E7 fragments displayed on phage particles. Functionality in ICC against formalin-fixed cervical cancer cell lines was demonstrated for ten mAbs; their high-risk specificity was confirmed by Western blot analysis and ICC on transiently transformed cells expressing high- or low-risk HPV E7. These mAbs were specific for one or several of the high-risk strains HPV16, 18, 31, 35 and 45. Specific E7 staining of liquid-based cytology (LBC) samples was demonstrated for seven mAbs and optimized protocols were established. The E716-41 and E718-79 mAbs demonstrated particularly strong and specific staining of cells stored in LBC fluid for at least 6 months. It is proposed that the high-risk HPV E7 staining protocols established in this study may have the potential to be included in a complementary test for the detection and identification of malignantly transformed cells, in for example atypical squamous cells of undetermined significance samples.

Multiplexed homogeneous proximity ligation assays for high-throughput protein biomarker research in serological material.

A high throughput protein biomarker discovery tool has been developed based on multiplexed proximity ligation assays in a homogeneous format in the sense of no washing steps. The platform consists of four 24-plex panels profiling 74 putative biomarkers with sub-pm sensitivity each consuming only 1 µl of human plasma sample. The system uses either matched monoclonal antibody pairs or the more readily available single batches of affinity purified polyclonal antibodies to generate the target specific reagents by covalently linking with unique nucleic acid sequences. These paired sequences are united by DNA ligation upon simultaneous target binding forming a PCR amplicon. Multiplex proximity ligation assays thereby converts multiple target analytes into real-time PCR amplicons that are individually quantified using microfluidic high capacity qPCR in nano liter volumes. The assay shows excellent specificity, even in multiplex, by its dual recognition feature, its proximity requirement, and most importantly by using unique sequence specific reporter fragments on both antibody-based probes. To illustrate the potential of this protein detection technology, a pilot biomarker research project was performed using biobanked plasma samples for the detection of colorectal cancer using a multivariate signature.

TD-11 workshop report: characterization of monoclonal antibodies to S100 proteins.

Fourteen monoclonal antibodies with specificity against native or recombinant antigens within the S100 family were investigated with regard to immunoreactivity. The specificities of the antibodies were studied using ELISA tests, Western blotting epitope mapping using competitive assays, and QCM technology. The mimotopes of antibodies against S100A4 were determined by random peptide phage display libraries. Antibody specificity was also tested by IHC and pair combinations evaluated for construction of immunoradiometric assays for S100B. Out of the 14 antibodies included in this report eight demonstrated specificity to S100B, namely MAbs 4E3, 4D2, S23, S53, 6G1, S21, S36, and 8B10. This reactivity could be classified into four different epitope groups using competing studies. Several of these MAbs did display minor reactivity to other S100 proteins when they were presented in denatured form. Only one of the antibodies, MAb 3B10, displayed preferential reactivity to S100A1; however, it also showed partial cross-reactivity with S100A10 and S100A13. Three antibodies, MAbs 20.1, 22.3, and S195, were specific for recombinant S100A4 in solution. Western blot revealed that MAb 20.1 and 22.3 recognized linear epitopes of S100A4, while MAb S195 reacted with a conformational dependent epitope. Surprisingly, MAb 14B3 did not demonstrate any reactivity to the panel of antigens used in this study.

Lab-on-a-chip for the isolation and characterization of circulating tumor cells.

A smart miniaturized system is being proposed for the isolation and characterization of circulating tumor cells (CTCs) directly from blood. Different microfluidic modules have been designed for cell enrichment and -counting, multiplex mRNA amplification as well as DNA detection. With the different modules at hand, future effort will focus on the integration of the modules in a fully automated, single platform.

Automated genotyping of circulating tumor cells.

Cancer remains a prominent health concern in modern societies. Continuous innovations and introduction of new technologies are essential to level or reduce current healthcare spending. A diagnostic platform to detect circulating tumor cells (CTCs) in peripheral blood may be most promising in this respect. CTCs have been proposed as a minimally invasive, prognostic and predictive marker to reflect the biological characteristics of tumors and are implemented in an increasing number of clinical studies. Still, their detection remains a challenge as they may occur at concentrations below one single cell per ml of blood. To facilitate their detection, here we describe microfluidic modules to isolate and genotype CTCs directly from clinical blood samples. In a first cell isolation and detection module, the CTCs are immunomagnetically enriched, separated and counted. In a second module and after cell lysis, the mRNA is reversely transcripted to cDNA, followed by a multiplex ligation probe amplification of 20 specific genetic markers and two control fragments. Following the multiplex ligation probe amplification reaction, the amplified fragments are electrochemically detected in a third and final module. Besides the design of the modules, their functionality is described using control samples. Further testing using clinical samples and integration of all modules in a single, fully automated smart miniaturized system will enable minimal invasive testing for frequent detection and characterization of CTCs.

Phage display for site-specific immunization and characterization of high-risk human papillomavirus specific E7 monoclonal antibodies.

The paper describes a method to use filamentous phage to display specific regions of proteins for immunization in order to direct the immune response towards a pre-defined region of the protein. The method called site-specific immunization (SSI) was evaluated using the E7 protein of oncogenic (high-risk) human papillomavirus (HPV) type 16 as a model system. This protein consists of sequence blocks also present in other viral and cellular proteins and in the corresponding protein of low-risk HPVs. A fragment of the HPV16 E7 oncoprotein specific for a group of high-risk viruses was identified by sequence comparison and displayed on filamentous phages in fusion with the major phage coat protein VIII. The recombinant phages triggered an immune response in mice against the full-length HPV16 E7 protein. Fusion of B-lymphocytes from the immunized animals with myeloma cells resulted in three hybridomas producing monoclonal antibodies (MAbs) with reactivity against the endogenous E7 protein. The specificity of the MAbs for the HPV16 E7 protein in cancer cell lines was confirmed by Western blot analyses and immunocytochemistry. The epitope of each MAb was roughly mapped by determining the reactivity against overlapping E7 fragments displayed on phage particles. The mimotopes of the MAbs were further determined by biopanning against a randomized peptide library displayed on phage and found to be unique for a sub-set of high-risk HPV E7 proteins. The combination of different phage display techniques for immunization and epitope mapping was efficient for generation and characterization of highly specific MAbs.

Production and Characterization of Monoclonal Antibodies for Immunoassay of the Lung Cancer Marker proGRP.

Progastrin-releasing peptide (proGRP) is a precursor of gastrin-releasing peptide, a hormone which is secreted from neuroendocrine cells. It has been shown to be a useful serum marker for small cell lung cancer. We raised monoclonal antibodies (MAbs) against proGRP with the primary aim of establishing a sensitive immunoassay. Immunization was performed with recombinant proGRP (amino acids 31-98) conjugated to thyroglobulin or with a DNP-modified peptide. Seven of the MAbs recognizing both recombinant and cell line-derived peptide were characterized and epitope-mapped. Based on cross-inhibition studies the antibodies could be categorized into three main groups. The molecular epitope assignment was studied by using phages displaying proGRP peptides, random peptide libraries displayed on phage and by pepscan analysis utilizing 10-mer biotinylated peptides. Two of the MAbs (E146, E172) bound to a defined region on the N-terminal part of proGRP(31-98), three recognized conformational-dependent epitopes in the middle of the peptide (E179, E180, E181) and two bound to the C-terminal part (E149, E168). Consensus sequences were obtained for MAbs E146, E149 and E168. The binding kinetics of the MAbs was determined by surface plasmon resonance, and a time-resolved immunofluorometric assay was established.

Specificity rescue and affinity maturation of a low-affinity IgM antibody against pro-gastrin-releasing peptide using phage display and DNA shuffling.

The objectives of the present study were to use phage display to rescue the specificity of an IgM antibody and by the use of DNA shuffling to construct a sublibrary from which mutants with higher affinity could be selected. As a test system, a hybridoma cell line producing low-affinity IgM against recombinant pro-gastrin-releasing peptide (ProGRP) was chosen as starting material for construction of a single-chain Fv (scFv) phage library. One clone, pGRP5, demonstrating affinity for the antigen, was selected for the study. Random mutations were introduced into the scFv sequence by DNA shuffling, and mutants with raised affinity were selected by biopanning against recombinant ProGRP. Clones with affinities improved by approximately two orders of magnitude were selected after the first round of DNA shuffling. An additional 8- to 9-fold rise in affinity was demonstrated in mutants after the second round of mutagenesis. Sequence analysis demonstrated changes primarily in the complementarity-determining region (CDR) H1, CDR L1 and CDR H3 as compared to the original clone. Thus, by the use of phage display in combination with DNA shuffling, the specificity of an IgM antibody was rescued and the affinity was raised almost three orders of magnitude.