Early detection of cancer in the general population: a blinded case-control study of p53 autoantibodies in colorectal cancer

Autoantibodies in cancer: a systematic review of their clinical role in the most prevalent cancers

Although blood autoantibodies were initially associated with autoimmune diseases, multiple evidence have been accumulated showing their presence in many types of cancer. This has opened their use in clinics, since cancer autoantibodies might be useful for early detection, prognosis, and monitoring of cancer patients. In this review, we discuss the different techniques available for their discovery and validation. Additionally, we discuss here in detail those autoantibody panels verified in at least two different reports that should be more likely to be specific of each of the four most incident cancers. We also report the recent developed kits for breast and lung cancer detection mostly based on autoantibodies and the identification of novel therapeutic targets because of the screening of the cancer humoral immune response. Finally, we discuss unsolved issues that still need to be addressed for the implementation of cancer autoantibodies in clinical routine for cancer diagnosis, prognosis, and/or monitoring.

Clinical practice guidelines for molecular tumor markers, 2nd edition review part 1

With advances in gene and protein analysis technologies, many target molecules that may be useful in cancer diagnosis have been reported. Therefore, the "Tumor Marker Study Group" was established in 1981 with the aim of "discovering clinically" useful molecules. Later, the name was changed to "Japanese Society for Molecular Tumor Marker Research" in 2000 in response to the remarkable progress in gene-related research. Currently, the world of cancer treatment is shifting from the era of representative tumor markers of each cancer type used for tumor diagnosis and treatment evaluation to the study of companion markers for molecular-targeted therapeutics that target cancer cells. Therefore, the first edition of the Molecular Tumor Marker Guidelines, which summarizes tumor markers and companion markers in each cancer type, was published in 2016. After publication of the first edition, the gene panel testing using next-generation sequencing became available in Japan in June 2019 for insured patients. In addition, immune checkpoint inhibitors have been indicated for a wide range of cancer types. Therefore, the 2nd edition of the Molecular Tumor Marker Guidelines was published in September 2021 to address the need to revise the guidelines. Here, we present an English version of the review (Part 1) of the Molecular Tumor Marker Guidelines, Second Edition.

p53 and p63 Proteoforms Derived from Alternative Splicing Possess Differential Seroreactivity in Colorectal Cancer with Distinct Diagnostic Ability from the Canonical Proteins

Colorectal cancer (CRC) is the third most common cancer and the second most frequent cause of cancer-related death worldwide. The detection in plasma samples of autoantibodies against specific tumor-associated antigens has been demonstrated to be useful for the early diagnosis of CRC by liquid biopsy. However, new studies related to the humoral immune response in cancer are needed to enable blood-based diagnosis of the disease. Here, our aim was to characterize the humoral immune response associated with the different p53 and p63 proteoforms derived from alternative splicing and previously described as aberrantly expressed in CRC. Thus, here we investigated the diagnostic ability of the twelve p53 proteoforms and the eight p63 proteoforms described to date, and their specific N-terminal and C-terminal end peptides, by means of luminescence HaloTag beads immunoassays. Full-length proteoforms or specific peptides were cloned as HaloTag fusion proteins and their seroreactivity analyzed using plasma from CRC patients at stages I-IV (n = 31), individuals with premalignant lesions (n = 31), and healthy individuals (n = 48). p53γ, Δ40p53β, Δ40p53γ, Δ133p53γ, Δ160p53γ, TAp63α, TAp63δ, ΔNp63α, and ΔNp63δ, together with the specific C-terminal end α and δ p63 peptides, were found to be more seroreactive against plasma from CRC patients and/or individuals with premalignant lesions than from healthy individuals. In addition, ROC (receiver operating characteristic) curves revealed a high diagnostic ability of those p53 and p63 proteoforms to detect CRC and premalignant individuals (AUC higher than 85%). Finally, electrochemical biosensing platforms were employed in POC-like devices to investigate their usefulness for CRC detection using selected p53 and p63 proteoforms. Our results demonstrate not only the potential of these biosensors for the simultaneous analysis of proteoforms’ seroreactivity, but also their convenience and versatility for the clinical detection of CRC by liquid biopsy. In conclusion, we here show that p53 and p63 proteoforms possess differential seroreactivity in CRC patients in comparison to controls, distinctive from canonical proteins, which should improve the diagnostic panels for obtaining a blood-based biomarker signature for CRC detection.

Antibodies as biomarkers for cancer risk: a systematic review

Increasing evidence has linked the humoral immune response with the development of various cancers. Therefore, there is growing interest in investigating the predictive value of antibodies to assess overall and tissue site-specific cancer risk. Given the large amount of antibody types and the broad scope of the search (i.e. cancer risk), the primary aim of this systematic review was to present an overview of the most researched antibodies (i.e. immunoglobulin (Ig) isotypes (IgG, IgM, IgA, and IgE), tumour and self-antigen-reactive antibodies, infection-related antibodies) in relation to overall and site-specific cancer risk. We identified various antibody types that have been associated with the risk of cancer. While no significant associations were found for IgM serum levels, studies found an inconsistent association among IgE, IgA, and IgG serum levels in relation to cancer risk. When evaluating antibodies against infectious agents, most studies reported a positive link with specific cancers known to be associated with the specific agent recognized by serum antibodies (i.e. helicobacter pylori and gastric cancer, hepatitis B virus and hepatocellular carcinoma, and human papillomavirus and cervical cancer). Several reports identified autoantibodies, as single biomarkers (e.g. anti-p53, anti-MUC1, and anti-CA125) but especially in panels of multiple autoantibodies, to have potential as diagnostic biomarkers for specific cancer types. Overall, there is emerging evidence associating certain antibodies to cancer risk, especially immunoglobulin isotypes, tumour-associated antigen-specific, and self-reactive antibodies. Further experimental studies are necessary to assess the efficacy of specific antibodies as markers for the early diagnosis of cancer.

Seroreactivity Against Tyrosine Phosphatase PTPRN Links Type 2 Diabetes and Colorectal Cancer and Identifies a Potential Diagnostic and Therapeutic Target

Colorectal cancer (CRC) and diabetes are two of the most prevalent chronic diseases worldwide with dysregulated receptor tyrosine kinase signaling and strong co-occurrence correlation. Plasma autoantibodies represent a promising early diagnostic marker for both diseases before symptoms appear. In this study, we explore the value of autoantibodies against receptor-type tyrosine-protein phosphatase-like N (PTPRN; full-length or selected domains) as diagnostic markers using a cohort of individuals with type 2 diabetes (T2D), CRC, or both diseases or healthy individuals. We show that PTPRN autoantibody levels in plasma discriminated between patients with T2D with and without CRC. Consistently, high PTPRN expression correlated with decreased survival of patients with CRC. Mechanistically, PTPRN depletion significantly reduced invasiveness of CRC cells in vitro and liver homing and metastasis in vivo by means of a dysregulation of the epithelial-mesenchymal transition and a decrease of the insulin receptor signaling pathway. Therefore, PTPRN autoantibodies may represent a particularly helpful marker for the stratification of patients with T2D at high risk of developing CRC. Consistent with the critical role played by tyrosine kinases in diabetes and tumor biology, we provide evidence that tyrosine phosphatases such as PTPRN may hold potential as therapeutic targets in patients with CRC.

Autoantibody to GNAS in Early Detection of Hepatocellular Carcinoma: A Large-Scale Sample Study Combined with Verification in Serial Sera from HCC Patients

The aim of this study was to explore the value of autoantibody to GNAS in the early detection of hepatocellular carcinoma (HCC). In a large-scale sample set of 912 participants (228 cases in each of HCC, liver cirrhosis (LC), chronic hepatitis B (CHB), and normal controls (NCs) groups), autoantibody to GNAS was detected with a positive result in 47.8% of HCC patients, which was significantly higher than that in patients with LC (35.1%), CHB (19.7%), and NCs (19.7%). Further analysis showed that the frequency of autoantibody to GNAS started increasing in compensated cirrhosis patients (37.0%) with a jump in decompensated cirrhosis patients (53.2%) and reached a peak in early HCC patients (62.4%). The increasing autoantibody response to GNAS in patients at different stages was closely associated with the progression of chronic liver lesions. The result from 44 human serial sera demonstrated that 5 of 11 (45.5%) HCC patients had elevated autoantibody to GNAS before and/or at diagnosis of HCC. Moreover, 46.1% and 62.4% of high positive rates in alpha-fetoprotein (AFP) negative and early-stage HCC patients can supplement AFP in early detection of HCC. These findings suggest that autoantibody to GNAS could be used as a potential biomarker for the early detection of HCC.

HSymM-guided engineering of the immunodominant p53 transactivation domain putative peptide antigen for improved binding to its anti-p53 monoclonal antibody

A novel engineering strategy to improve autoantibody detection with peptide fragments derived from the parent antigen is presented. The model system studied was the binding of the putative p53 TAD peptide antigen (residues 46-55) to its cognate anti-p53 antibody, ab28. Each engineered peptide contained the full decapeptide epitope and differed only in the flanking regions. Since minimal structural information was available to guide the design, a simple epitope:paratope binding model was applied. The Hidden Symmetry Model, which we recently reported, was used to guide peptide design and estimate per-residue contributions to interaction free energy as a function of added C- and N-terminal flanking peptides. Twenty-four peptide constructs were designed, synthesized, and assessed for binding affinity to ab28 by surface plasmon resonance, and a subset of these peptides were evaluated in a simulated immunoassay for limit of detection. Many peptides exhibited over 200-fold enhancements in binding affinity and improved limits of detection. The epitope was reevaluated and is proposed to be the undecapeptide corresponding to residues 45-55. HSymM calculated binding free energy and experimental data were found to be in good agreement (R2 > 0.75).

IgM and IgA augmented autoantibody signatures improve early-stage detection of colorectal cancer prior to nodal and distant spread

OBJECTIVES

Tumor-associated autoantibodies (AAbs) in individuals with cancer can precede clinical diagnosis by several months to years. The objective of this study was to determine whether the primary immune response in form of IgM and gut mucosa-associated IgA can aid IgG AAbs in the detection of early-stage colorectal cancer (CRC).

METHODS

We developed a novel protein array comprising 492 antigens seropositive in CRC. The array was used to profile IgG, IgM and IgA antibody signatures in 99 CRC patients and 99 sex- and age-matched non-cancer controls. A receiver operating curve (ROC), Kaplan-Meier survival analysis and univariate and multivariate Cox regression analyses were conducted.

RESULTS

We identified a panel of 16 multi-isotype AAbs with a cumulative sensitivity of 91% and specificity of 74% (AUC 0.90, 95% CI: 0.850-0.940) across all CRC stages. IgM and IgG isotypes were conversely associated with disease stage with IgM contributing significantly to improved stage I and II sensitivity of 96% at 78% specificity (AUC 0.928, 95% CI: 0.884-0.973). A single identified IgA AAb reached an overall sensitivity of 5% at 99% specificity (AUC 0.520, 95% CI: 0.440-0.601) balanced across all CRC stages. Kaplan-Meier analysis revealed that se33-1 (ZNF638) IgG AAbs were associated with reduced 5-year overall survival (log-rank test, P = 0.012), whereas cumulative IgM isotype signatures were associated with improved 5-year overall survival (log-rank test, P = 0.024).

CONCLUSION

IgM AAbs are associated with early-stage colorectal cancer. Combining IgG, IgM and IgA AAbs is a novel strategy to improve early diagnosis of cancers.

Autoantibodies in the diagnosis, prognosis, and prediction of colorectal cancer

Colorectal cancer (CRC) is the second-most commonly diagnosed cancer worldwide. Early diagnosis improves prognosis and long-term outcomes. Several studies have found tumor-associated autoantibodies in CRC patients. We aimed to provide an overview on CRC-associated autoantibodies and their reported diagnostic, prognostic, and predictive performance when used singly or in combination. We systematically reviewed studies on CRC-related autoantibodies published till March 2018 and critically analyzed the role of these autoantibodies in CRC. In general, autoantibodies were of low sensitivity when tested individually and the diagnostic characteristics improved when tested in combination. Autoantibodies against CCD83, carcinoembryonic antigen, MAPKAPK3, RPH 3AL, SEC61b, and SPAG9 showed high sensitivity and specificity when tested alone. When tested in combination, autoantibodies against three antigens (PIM1, MAPKAPK3, and ACVR2B) showed high sensitivity and specificity. So far, most CRC-associated autoantibodies have been evaluated in single or in a small number of studies. In contrast, anti-p53 antibodies have been studied in a larger number of CRC studies, but, so far, none of them have high diagnostic characteristics. CRC-associated autoantibodies are detectable from the early stages of malignancy, pointing to their possible use in the early detection of CRC. Some studies suggest that CRC-associated autoantibodies may be a guide to prognosis in CRC.

Global functions of O-glycosylation: promises and challenges in O-glycobiology

Mucin type O-glycosylation is one of the most diverse types of glycosylation, playing essential roles in tissue development and homeostasis. In complex organisms, O-GalNAc glycans comprise a substantial proportion of the glycocalyx, with defined functions in hemostatic, gastrointestinal, and respiratory systems. Furthermore, O-GalNAc glycans are important players in host-microbe interactions, and changes in O-glycan composition are associated with certain diseases and metabolic conditions, which in some instances can be used for diagnosis or therapeutic intervention. Breakthroughs in O-glycobiology have gone hand in hand with the development of new technologies, such as advancements in mass spectrometry, as well as facilitation of genetic engineering in mammalian cell lines. High-throughput O-glycoproteomics have enabled us to draw a comprehensive map of O-glycosylation, and mining this information has supported the definition and confirmation of functions related to site-specific O-glycans. This includes protection from proteolytic cleavage, as well as modulation of binding affinity or receptor function. Yet, there is still much to discover, and among the important next challenges will be to define the context-dependent functions of O-glycans in different stages of cellular differentiation, cellular metabolism, host-microbiome interactions, and in disease. In this review, we present the achievements and the promises in O-GalNAc glycobiology driven by technological advances in analytical methods, genetic engineering, and systems biology.

Identifying Novel Biomarkers Ready for Evaluation in Low-Prevalence Populations for the Early Detection of Lower Gastrointestinal Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Lower gastrointestinal (GI) cancers are a major cause of cancer deaths worldwide. Prognosis improves with earlier diagnosis, and non-invasive biomarkers have the potential to aid with early detection. Substantial investment has been made into the development of biomarkers; however, studies are often carried out in specialist settings and few have been evaluated for low-prevalence populations.

METHODS

We aimed to identify novel biomarkers for the detection of lower GI cancers that have the potential to be evaluated for use in primary care. MEDLINE, Embase, Emcare and Web of Science were systematically searched for studies published in English from January 2000 to October 2019. Reference lists of included studies were also assessed. Studies had to report on measures of diagnostic performance for biomarkers (single or in panels) used to detect colorectal or anal cancers. We included all designs and excluded studies with fewer than 50 cases/controls. Data were extracted from published studies on types of biomarkers, populations and outcomes. Narrative synthesis was used, and measures of specificity and sensitivity were meta-analysed where possible.

RESULTS

We identified 142 studies reporting on biomarkers for lower GI cancers, for 24,844 cases and 45,374 controls. A total of 378 unique biomarkers were identified. Heterogeneity of study design, population type and sample source precluded meta-analysis for all markers except methylated septin 9 (mSEPT9) and pyruvate kinase type tumour M2 (TuM2-PK). The estimated sensitivity and specificity of mSEPT9 was 80.6% (95% CI 76.6-84.0%) and 88.0% (95% CI 79.1-93.4%) respectively; TuM2-PK had an estimated sensitivity of 81.6% (95% CI 75.2-86.6%) and specificity of 80.1% (95% CI 76.7-83.0%).

CONCLUSION

Two novel biomarkers (mSEPT9 and TuM2-PK) were identified from the literature with potential for use in lower-prevalence populations. Further research is needed to validate these biomarkers in primary care for screening and assessment of symptomatic patients.

Auto-antibodies to p53 and the Subsequent Development of Colorectal Cancer in a U.S. Prospective Cohort Consortium

BACKGROUND

Auto-antibodies to tumor suppressor p53 are found in a subset of patients with colorectal cancer. A recent prospective study in the United States has reported a significant 1.8-fold increased odds for colorectal cancer development with prediagnostic seropositivity to p53. In this study, we sought to examine this association in a U.S. colorectal cancer cohort consortium to evaluate the potential utility of p53 auto-antibodies as an early biomarker for colorectal cancer.

METHODS

Auto-antibodies to p53 were measured in prediagnostic blood samples of 3,702 incident colorectal cancer cases and 3,702 controls, matched by age, race, and sex, from 9 U.S. prospective cohorts. The association of seropositivity to p53 with colorectal cancer risk, overall and by time between blood draw and diagnosis, was determined by conditional logistic regression.

RESULTS

Overall, 5% of controls and 7% of cases were seropositive to p53, resulting in a statistically significant 33% increased colorectal cancer risk [odds ratio (OR), 1.33; 95% confidence interval (CI), 1.09-1.61]. By follow-up time, the association was only significant with colorectal cancer diagnoses within 4 years after blood draw (OR, 2.27; 95% CI, 1.62-3.19), but not thereafter (OR, 0.97; 95% CI, 0.76-1.24).

CONCLUSIONS

In this large consortium of prospective cohorts, we found that prediagnostic seropositivity to tumor suppressor p53 was significantly associated with an over 2-fold increased odds of developing colorectal cancer within 4 years after blood draw.

IMPACT

Our finding suggests that p53 seropositivity may not be a useful predictor of long-term colorectal cancer risk; however, it might be considered as a marker to aid in the early diagnosis of colorectal cancer.

Identification and Validation of Novel Serum Autoantibody Biomarkers for Early Detection of Colorectal Cancer and Advanced Adenoma

Background: Colorectal cancer (CRC) comprises a large proportion of malignant tumors, and early detection of CRC is critical for effective treatment and optimal prognosis. We aimed to discover and validate serum autoantibodies for early detection of CRC.

Methods: Combined with CRC-associated autoantibodies discovered by serological proteome and multiplex analyses, 26 predefined autoantibodies were evaluated in 315 samples (130 CRCs, 75 advanced adenomas, and 110 healthy controls) by protein microarray analysis. Autoantibodies with potential detection value were verified by enzyme-linked immunosorbent assays (ELISAs). Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the accuracy of the biomarkers.

Results: Four serum autoantibodies (ALDH1B1, UQCRC1, CTAG1, and CENPF) showed statistically different levels between patients with advanced neoplasm (CRC or advanced adenoma) and controls in microarray analysis, which were validated by ELISAs. Among the four biomarkers, the ALDH1B1 autoantibody showed the highest detection value with area under the curve (AUC) values of 0.70 and 0.74 to detect CRC and advanced adenoma with sensitivities of 75.68 and 62.31% and specificities of 63.06 and 73.87%, respectively. By combining the four biomarkers, the performance was improved with an AUC of 0.79 to detect CRC and advanced adenomas.

Conclusion: The ALDH1B1 autoantibody has a good potential for early detection of CRC and advanced adenoma, and measuring serum autoantibodies against tumor-associated antigens may improve detection of early CRC.

Impaired O-Glycosylation at Consecutive Threonine TTX Motifs in Mucins Generates Conformationally Restricted Cancer Neoepitopes

Autoantibody signatures of circulating mucin fragments stem from cancer tissues, and microenvironments are promising biomarkers for cancer diagnosis and therapy. This study highlights dynamic epitopes generated by aberrantly truncated immature O-glycosylation at consecutive threonine motifs (TTX) found in mucins and intrinsically disordered proteins (IDPs). NMR analysis of synthetic mucin models having glycosylated TTX motifs and colonic MUC2 tandem repeats (TRs) containing TTP and TTL moieties unveils a general principle that O-glycosylation at TTX motifs generates a highly extended and rigid conformation in IDPs. We demonstrate that the specific conformation of glycosylated TTX motifs in MUC2 TRs is rationally rearranged by concerted motions of multiple dihedral angles and noncovalent interactions between the carbohydrate and peptide region. Importantly, this canonical conformation of glycosylated TTX motifs minimizes steric crowding of glycans attached to threonine residues, in which O-glycans possess restricted orientations permitting further sugar extension. An antiadhesive microarray displaying synthetic MUC2 derivatives elicited the presence of natural autoantibodies to MUC2 with impaired O-glycosylation at TTX motifs in sera of healthy volunteers and patients diagnosed with early stage colorectal cancer (CRC). Interestingly, autoantibody levels in sera of the late stage CRC patients were distinctly lower than those of early stage CRC and normal individuals, indicating that the anti-MUC2 humoral response to MUC2 neoepitopes correlates inversely with the CRC stage of patients. Our results uncovered the structural basis of the creation of dynamic epitopes by immature O-glycosylation at TTX motifs in mucins that facilitates the identification of high-potential targets for cancer diagnosis and therapy.

Multiplexed monitoring of a novel autoantibody diagnostic signature of colorectal cancer using HaloTag technology-based electrochemical immunosensing platform

Background and Purpose: The humoral immune response in cancer patients can be used for early detection of the disease. Autoantibodies raised against tumor-associated antigens (TAAs) are promising clinical biomarkers for reliable cancer diagnosis, prognosis, and therapy monitoring. In this study, an electrochemical disposable multiplexed immunosensing platform able to integrate difficult- and easy-to-express colorectal cancer (CRC) TAAs is reported for the sensitive determination of eight CRC-specific autoantibodies. Methods: The electrochemical immunosensing approach involves the use of magnetic microcarriers (MBs) as solid supports modified with covalently immobilized HaloTag fusion proteins for the selective capture of specific autoantibodies. After magnetic capture of the modified MBs onto screen-printed carbon working electrodes, the amperometric responses measured using the hydroquinone (HQ)/H2O2 system were related to the levels of autoantibodies in plasma. Results: The biosensing platform was applied to the analysis of autoantibodies against 8 TAAs described for the first time in this work in plasma samples from healthy asymptomatic individuals (n=3), and patients with high-risk of developing CRC (n=3), and from patients already diagnosed with colorectal (n=3), lung (n=2) or breast (n=2) cancer. The developed bioplatform demonstrated an improved discrimination between CRC patients and controls (asymptomatic healthy individuals and breast and lung cancer patients) compared to an ELISA-like luminescence test. Conclusions: The proposed methodology uses a just-in-time produced protein in a simpler protocol, with low sample volume, and involves cost-effective instrumentation, which could be used in a high-throughput manner for reliable population screening to facilitate the detection of early CRC patients at affordable cost.

Autoantibodies as biomarkers for colorectal cancer: A systematic review, meta-analysis, and bioinformatics analysis

Colorectal cancer is a very common cancer worldwide. Serum tumor-associated autoantibodies (TAAbs), especially the anti-p53 autoantibody, may be promising biomarkers to detect early-stage colorectal cancer. This study aimed to identify all known autoantibodies and their value in colorectal cancer diagnosis, as well as exploring the underlying connections and mechanisms through a bioinformatics analysis. Databases were used to select available articles of TAAbs in colorectal cancer. In a meta-analysis of the anti-p53 autoantibody, the diagnostic odds ratio and area under the curve (AUC) of the summary receiver-operating characteristic (SROC) curve were calculated using Stata 12.0 and Meta-Disc 1.4. We identified 73 articles including 199 single autoantibodies and 42 multiple autoantibodies. The maximum value of Youden's index was 0.76, combining c-MYC, p53, cyclin B1, p62, Koc, IMP1, and survivin. The diagnostic odds ratio for anti-p53 autoantibody at all stages was 10.86 (95% CI 8.40, 14.06) with low heterogeneity (I² = 40.3%) and the AUC of the SROC curve was 0.82. For the anti-p53 autoantibody in early-stage colorectal cancer, the diagnostic odds ratio was 4.82 (95% CI 2.95, 7.87) with heterogeneity (I² = 7.9%) and the AUC of the SROC curve was 0.72. Eighty-seven autoantibodies were selected for bioinformatics analyses. We found that the most enriched functional terms and protein-protein interactions may relate to the mechanism of autoantibody generation. In summary, our study summarized the diagnostic value of TAAbs in colorectal cancer, either as single molecules or in combination. Bioinformatics analyses may be a new approach to explore the mechanism of autoantibody generation.

The specific seroreactivity to ∆Np73 isoforms shows higher diagnostic ability in colorectal cancer patients than the canonical p73 protein

The p53-family is tightly regulated at transcriptional level. Due to alternative splicing, up to 40 different theoretical proteoforms have been described for p73 and at least 20 and 10 for p53 and p63, respectively. However, only the canonical proteins have been evaluated as autoantibody targets in cancer patients for diagnosis. In this study, we have cloned and expressed in vitro the most upregulated proteoforms of p73, ΔNp73α and ΔNp73β, for the analysis of their seroreactivity by a developed luminescence based immunoassay test using 145 individual plasma from colorectal cancer, premalignant individuals and healthy controls. ∆Np73α seroreactivity showed the highest diagnostic ability to discriminate between groups. The combination of ∆Np73α, ∆Np73β and p73 proteoforms seroreactivity were able to improve their individual diagnostic ability. Competitive inhibition experiments further demonstrated the presence of unique specific epitopes in ΔNp73 isoforms not present in p73, with several colorectal patients showing unique and specific seroreactivity to the ΔNp73 proteoforms. Overall, we have increased the complexity of the humoral immune response to the p53-family in cancer patients, showing that the proteoforms derived from the alternative splicing of p73 possess a higher diagnostic ability than the canonical protein, which might be extensive for p53 and p63 proteins.

Species-specific mechanisms of tumor suppression are fundamental drivers of vertebrate speciation: critical implications for the 'war on cancer'

We recently reported our detection of an anthropoid primate-specific, 'kill switch' tumor suppression system that reached its greatest expression in humans, but that is fully functional only during the first twenty-five years of life, corresponding to the primitive human lifespan that has characterized the majority of our species' existence. This tumor suppression system is based upon the kill switch being triggered in cells in which p53 has been inactivated; such kill switch consisting of a rapid, catastrophic increase in ROS caused by the induction of irreversible uncompetitive inhibition of glucose-6- phosphate dehydrogenase (G6PD), which requires high concentrations of both inhibitor (DHEA) and G6P substrate. While high concentrations of intracellular DHEA are readily available in primates from the importation and subsequent de-sulfation of circulating DHEAS into p53-affected cells, both an anthropoid primate-specific sequence motif (GAAT) in the glucose-6-phosphatase (G6PC) promoter, and primate-specific inactivation of de novo synthesis of vitamin C by deletion of gulonolactone oxidase (GLO) were required to enable accumulation of G6P to levels sufficient to enable irreversible uncompetitive inhibition of G6PD. Malignant transformation acts as a counterforce opposing vertebrate speciation, particularly increases in body size and lifespan that enable optimized exploitation of particular niches. Unique mechanisms of tumor suppression that evolved to enable niche exploitation distinguish vertebrate species, and prevent one vertebrate species from serving as a valid model system for another. This here-to-fore unrecognized element of speciation undermines decades of cancer research data, using murine species, which presumed universal mechanisms of tumor suppression, independent of species. Despite this setback, the potential for pharmacological reconstitution of the kill switch tumor suppression system that distinguishes our species suggests that 'normalization' of human cancer risk, from its current 40% to the 4% of virtually all other large, long-lived species, represents a realistic near-term goal.

A novel algorithm to improve specificity in ovarian cancer detection

BACKGROUND

Measurement of autoantibodies (AAbs) to tumor associated antigens has been proposed to aid in the early detection of ovarian cancer with high specificity. Here we describe a multiplex approach to evaluate selected peptide epitopes of p53 protein, and propose a novel approach to increase specificity and potentially sensitivity for discrimination between healthy women and women with cancerous masses.

MATERIALS AND METHODS

20-mer overlapping peptide epitopes of p53, generated by mapping the complete p53 sequence, were evaluated in a multiplex immunoassay for their detection of serum AAbs in patients with ovarian cancer, using Luminex technology. AAbs to the selected peptides and to p53 full length protein were then detected in a multiplex immunoassay evaluating 359 sera from healthy women and 285 sera from patients with early and late stage ovarian cancer. CA-125 levels were measured in all p53 AAb-positive sera.

RESULTS

We considered the AAb results together to identify sera where both the full length protein and at least one selected peptide epitope were positive and chose cutoffs that reduced false positives from these AAbs to 1/359 samples, improving specificity. Using this combined approach, we could identify 7 AAb-positive patients that were negative for CA-125 (concentrations below 35 IU/mL); this represents 26% of the p53 positive patients in the total population.

CONCLUSION

By detecting p53 AAbs in CA-125-negative sera, we demonstrated that combining measurement of AAbs to the full length p53 protein and one or more selected epitopes can potentially improve sensitivity and specificity for ovarian cancer detection.

Developments in Point-of-Care Diagnostic Technology for Cancer Detection

Cancer is the cause of death for one in seven individuals worldwide. It is widely acknowledged that screening and early diagnosis are of vital importance for improving the likelihood of recovery. However, given the costly, time-consuming, and invasive nature of the many methods currently in use, patients often do not take advantage of the services available to them. Consequently, many researchers are exploring the possibility of developing fast, reliable, and non-invasive diagnostic tools that can be used directly or by local physicians at the point-of-care. Herein, we look at the use of established biomarkers in cancer therapy and investigate emerging biomarkers exhibiting future potential. The incorporation of these biomarkers into point-of-care devices could potentially reduce the strain currently experienced by screening programs in hospitals and healthcare systems. Results derived from point-of-care tests should be accurate, sensitive, and generated rapidly to assist in the selection of the best course of treatment for optimal patient care. Essentially, point-of-care diagnostics should enhance the well-being of patients and lead to a reduction in cancer-related deaths.

Zoledronic Acid Regulates Autophagy and Induces Apoptosis in Colon Cancer Cell Line CT26

Zoledronic acid (ZOL) is the third generation of bisphosphonates, which can inhibit many tumors growth, especially to inhibit the growth of colon cancer. However, the molecular mechanism is still very mysterious. In this study, we observed that ZOL could regulate CT26 colon cancer cells autophagy, promote CT26 cells apoptosis, and inhibit CT26 cells proliferation. Western blotting analysis showed that proapoptosis protein caspase-3 was basically unchanged, whereas the expression of the activated caspase-3 was significantly increased, after CT26 cells were treated with different doses of zoledronic acid. Western blot also showed that ZOL could significantly affect the expression of p-p53 and autophagy-related proteins beclin-1 and p62. In conclusion, the antitumor effect of ZOL on CT26 colon cancer cells in vitro is achieved by apoptosis induction and autophagy regulation, resulting in inhibition of cell proliferation.

Prediagnostic Antibodies to Serum p53 and Subsequent Colorectal Cancer

Background: The presence of circulating antibodies to the p53 tumor suppressor protein is a potential early detection colorectal cancer biomarker. However, studies of prediagnostic measures of p53 seropositivity in relation to colorectal cancer risk are limited.Methods: We conducted a nested case-control study of serum p53 autoantibodies and risk of colorectal cancer within the Cancer Prevention Study-II Nutrition Cohort. Among cohort participants who were cancer free at the time of blood collection, 392 were subsequently diagnosed with colorectal cancer over 11 years of follow-up. Two controls were matched to each case on birth date, blood draw date, race, and sex. Autoantibodies to p53 were detected in 41 of the 392 cases (10.5%) and 49 of the 774 controls (6.3%).Results: Participants who were seropositive for p53 antibodies before diagnosis were more likely to be subsequently diagnosed with colorectal cancer [RR = 1.77; 95% confidence interval (CI), 1.12-2.78]. This association was strongest within 3 years of diagnosis (RR = 2.26; 95% CI, 1.06-4.83). An association was also suggested when colorectal cancer was diagnosed 4 to <6 years after p53 measurement (RR = 1.84; 95% CI, 0.89-3.79), but not 6 or more years later (RR = 1.15; 95% CI, 0.44-2.99).Conclusions: If these results are confirmed, serum p53 antibodies may be useful on a panel of early detection markers for colorectal cancer.Impact: Individuals who were seropositive for p53 antibodies were twice as likely to develop colorectal cancer within the next 3 years compared with those who were seronegative. This marker is a good candidate for inclusion on an early detection marker panel for colorectal cancer. Cancer Epidemiol Biomarkers Prev; 27(2); 219-23. ©2017 AACR.

De novo expression of human polypeptide N-acetylgalactosaminyltransferase 6 (GalNAc-T6) in colon adenocarcinoma inhibits the differentiation of colonic epithelium

Aberrant expression of O-glycans is a hallmark of epithelial cancers. Mucin-type O-glycosylation is initiated by a large family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) that target different proteins and are differentially expressed in cells and organs. Here, we investigated the expression patterns of all of the GalNAc-Ts in colon cancer by analyzing transcriptomic data. We found that GalNAc-T6 was highly up-regulated in colon adenocarcinomas but absent in normal-appearing adjacent colon tissue. These results were verified by immunohistochemistry, suggesting that GalNAc-T6 plays a role in colon carcinogenesis. To investigate the function of GalNAc-T6 in colon cancer, we used precise gene targeting to produce isogenic colon cancer cell lines with a knockout/rescue system for GALNT6 GalNAc-T6 expression was associated with a cancer-like, dysplastic growth pattern, whereas GALNT6 knockout cells showed a more normal differentiation pattern, reduced proliferation, normalized cell-cell adhesion, and formation of crypts in tissue cultures. O-Glycoproteomic analysis of the engineered cell lines identified a small set of GalNAc-T6-specific targets, suggesting that this isoform has unique cellular functions. In support of this notion, the genetically and functionally closely related GalNAc-T3 homolog did not show compensatory functionality for effects observed for GalNAc-T6. Taken together, these data strongly suggest that aberrant GalNAc-T6 expression and site-specific glycosylation is involved in oncogenic transformation.

Prospective evaluation of 64 serum autoantibodies as biomarkers for early detection of colorectal cancer in a true screening setting

Novel blood-based screening tests are strongly desirable for early detection of colorectal cancer (CRC). We aimed to identify and evaluate autoantibodies against tumor-associated antigens as biomarkers for early detection of CRC. 380 clinically identified CRC patients and samples of participants with selected findings from a cohort of screening colonoscopy participants in 2005–2013 (N=6826) were included in this analysis. Sixty-four serum autoantibody markers were measured by multiplex bead-based serological assays. A two-step approach with selection of biomarkers in a training set, and validation of findings in a validation set, the latter exclusively including participants from the screening setting, was applied. Anti-MAGEA4 exhibited the highest sensitivity for detecting early stage CRC and advanced adenoma. Multi-marker combinations substantially increased sensitivity at the price of a moderate loss of specificity. Anti-TP53, anti-IMPDH2, anti-MDM2 and anti-MAGEA4 were consistently included in the best-performing 4-, 5-, and 6-marker combinations. This four-marker panel yielded a sensitivity of 26% (95% CI, 13–45%) for early stage CRC at a specificity of 90% (95% CI, 83–94%) in the validation set. Notably, it also detected 20% (95% CI, 13–29%) of advanced adenomas. Taken together, the identified biomarkers could contribute to the development of a useful multi-marker blood-based test for CRC early detection.

Development of a multiplexed tumor-associated autoantibody-based blood test for the detection of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignancies worldwide, and early diagnosis is vital to improving prognoses. We explored the diagnostic potential of a multiplex autoantibody panel as a biomarker for the detection of CRC by ELISA.

METHODS

In total, 192 serum samples (92 CRC and 100 matched controls) were tested against a panel of 12 tumor-associated antigens (TAAs): RPH3AL, RPL36, SLP2, p53, survivin, ANAXA4, SEC61B, CCCAP, NYCO16, NMDAR, PLSCR1, and HDAC5. Individual and combined autoantibody signatures were examined.

RESULTS

Compared to individual autoantibody markers, the combinations of TAAs provided better discrimination between tumorous and normal sera. The overall sensitivity of a selected panel of four antibodies (anti-SLP2, -p53, -SEC61B, and -PLSCR1) was 64.1%, with a specificity of 80% that increased to 83.7% when carcinoembryonic antigen (CEA) measurement was added. Furthermore, the sensitivity of the panel of four antibodies for early and advanced stages of CRC was 66.7% and 62%, increasing to 88.3% and 84%, respectively, when CEA was added.

CONCLUSIONS

We identified a panel of four antibodies as a promising diagnostic biomarker for the detection of CRC.

Elevation of TP53 Autoantibody Before CA125 in Preclinical Invasive Epithelial Ovarian Cancer

Purpose: The TP53 tumor-suppressor gene is mutated in >95% of high-grade serous ovarian cancers. Detecting an autologous antibody response to TP53 that might improve early detection.Experimental Design: An immunoassay was developed to measure TP53 autoantibody in sera from 378 cases of invasive epithelial ovarian cancer and 944 age-matched healthy controls from the United States, Australia, and the United Kingdom. Serial preclinical samples from cases and controls were also assayed from the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).Results: Using a cutoff value of 78 U/mL to achieve a specificity of 97.4%, TP53 autoantibody was elevated in 30% of 50 cases from MD Anderson, 21.3% of 108 cases from the Australian Ovarian Cancer Study, and 21% of 220 cases from the UKCTOCS. Among 164 cases with rising CA125 detected with the UKCTOCS risk of ovarian cancer algorithm (ROCA), 20.7% had elevated TP53 autoantibody. In cases missed by the ROCA, 16% of cases had elevated TP53 autoantibody. Of the 34 ovarian cancer cases detected with the ROCA, TP53 autoantibody titers were elevated 11.0 months before CA125. In the 9 cases missed by the ROCA, TP53 autoantibody was elevated 22.9 months before cancer diagnosis. Similar sensitivity was obtained using assays with specific mutant and wild-type TP53.Conclusions: TP53 autoantibody levels provide a biomarker with clinically significant lead time over elevation of CA125 or an elevated ROCA value. Quantitative assessment of autoantibodies in combination with CA125 holds promise for earlier detection of invasive epithelial ovarian cancer. Clin Cancer Res; 23(19); 5912-22. ©2017 AACR.

The Prevalence of Cancer-Associated Autoantibodies in Patients with Gastric Cancer and Progressive Grades of Premalignant Lesions

Background: Serum autoantibodies against tumor-associated antigens (TAAs) are detectable in early-stage gastric cancer patients; however, the time point during cancerogenesis when they appear in circulation is still obscure.Methods: In this study, we developed a recombinant antigen microarray and analyzed the prevalence of autoantibodies against 102 TAAs in 829 gastric cancer patients and 929 healthy controls from Caucasian and Asian populations, as well as 100 patients with chronic atrophic gastritis and 775 individuals staged according to different grades of intestinal metaplasia.Results: Six antigens, including CTAG1B/CTAG2, DDX53, IGF2BP2, TP53, and MAGEA3, were predominantly reacting with sera from gastric cancer patients when compared with healthy controls, and the seroreactivity was associated with intestinal-type gastric cancer, but not with patients' Helicobacter pylori status, grade, age, gender, or stage of gastric cancer. We detected gastric cancer-associated seroreactivity in 13% of patients with advanced/severe intestinal metaplasia, which was increased in comparison with mild/moderate intestinal metaplasia (5.3%) and was comparable with that seen in early-stage gastric cancer patients (12%). Moreover, by testing serum samples taken 1 to 9 years before the clinical diagnosis of 18 incident gastric cancer cases, we detected autoantibody responses against several TAAs-SOX2, MYC, BIRC5, IGF2BP1, and MUC1.Conclusions: Our results suggest that humoral immune response against TAAs is generated already during premalignant stages.Impact: Based on the obtained results, cancer-associated autoantibodies might make a valuable contribution to the stratification of high-risk patients with premalignant lesions in the stomach through enhancing the positive predictive power of existing risk models. Cancer Epidemiol Biomarkers Prev; 26(10); 1564-74. ©2017 AACR.

Gold-loaded nanoporous iron oxide nanocubes: a novel dispersible capture agent for tumor-associated autoantibody analysis in serum

Autoantibodies are produced against tumor associated antigens (TAAs) long before the appearance of any symptoms and thus can serve as promising, non-invasive biomarkers for early diagnosis of cancer. Current conventional methods for autoantibody detection are highly invasive and mostly provide diagnosis in the later stages of cancer. Herein we report a new electrochemical method for early detection of p53 autoantibodies against colon cancer using a strategy that combines the strength of gold-loaded nanoporous iron oxide nanocube (Au@NPFe₂O₃NC)-based capture and purification while incorporating the inherent simplicity, inexpensive, and portable nature of the electrochemical and naked-eye colorimetric readouts. After the functionalisation of Au@NPFe₂O₃NC with p53 antigens, our method utilises a two-step strategy that involves (i) magnetic capture and isolation of autoantibodies using p53/Au@NPFe₂O₃NC as 'dispersible nanocapture agents' in serum samples and (ii) subsequent detection of autoantibodies through a peroxidase-catalyzed reaction on a commercially available disposable screen-printed electrode or naked-eye detection in an Eppendorf tube. This method has demonstrated a good sensitivity (LOD = 0.02 U mL^-1) and reproducibility (relative standard deviation, %RSD = <5%, for n = 3) for detecting p53 autoantibodies in serum and has also been successfully applied to analyse a small cohort of clinical samples obtained from colorectal cancer. We believe that the highly inexpensive, rapid, sensitive, and specific nature of our assay could potentially aid in the development of an early diagnostic tool for cancer and related diseases.

Autoantibody biomarkers for the detection of serous ovarian cancer

Objective The purpose of this study was to identify a panel of novel serum tumor antigen-associated autoantibody (TAAb) biomarkers for the diagnosis of high-grade serous ovarian cancer.

METHODS

To detect TAAb we probed high-density programmable protein microarrays (NAPPA) containing 10,247 antigens with sera from patients with serous ovarian cancer (n=30 cases/30 healthy controls) and measured bound IgG. We identified 735 promising tumor antigens and evaluated these with an independent set of serous ovarian cancer sera (n=30 cases/30 benign disease controls/30 healthy controls). Thirty-nine potential tumor autoantigens were identified and evaluated using an orthogonal programmable ELISA platform against a total of 153 sera samples (n=63 cases/30 benign disease controls/60 healthy controls). Sensitivities at 95% specificity were calculated and a classifier for the detection of high-grade serous ovarian cancer was constructed.

RESULTS

We identified 11-TAAbs (ICAM3, CTAG2, p53, STYXL1, PVR, POMC, NUDT11, TRIM39, UHMK1, KSR1, and NXF3) that distinguished high-grade serous ovarian cancer cases from healthy controls with a combined 45% sensitivity at 98% specificity.

CONCLUSION

These are potential circulating biomarkers for the detection of serous ovarian cancer, and warrant confirmation in larger clinical cohorts.

Application of flat panel OLED display technology for the point-of-care detection of circulating cancer biomarkers

Point-of-care molecular diagnostics can provide efficient and cost-effective medical care, and they have the potential to fundamentally change our approach to global health. However, most existing approaches are not scalable to include multiple biomarkers. As a solution, we have combined commercial flat panel OLED display technology with protein microarray technology to enable high-density fluorescent, programmable, multiplexed biorecognition in a compact and disposable configuration with clinical-level sensitivity. Our approach leverages advances in commercial display technology to reduce pre-functionalized biosensor substrate costs to pennies per cm². Here, we demonstrate quantitative detection of IgG antibodies to multiple viral antigens in patient serum samples with detection limits for human IgG in the 10 pg/mL range. We also demonstrate multiplexed detection of antibodies to the HPV16 proteins E2, E6, and E7, which are circulating biomarkers for cervical as well as head and neck cancers.

Paradoxical Reductions in Serum Anti-p53 Autoantibody Levels by Chemotherapy in Unresectable Colorectal Cancer: An Observational Study

OBJECTIVE

The anti-p53 autoantibody is an emerging tumor marker that is commonly produced in response to p53 mutations. The usefulness of this antibody has been suggested in screening for and the monitoring of recurrence in colorectal cancer; however, its significance as a marker during chemotherapy remains largely unknown.

METHODS

We measured serum anti-p53 antibody levels in patients with unresectable colorectal cancer who underwent first-line systemic chemotherapy. Tumor responses were evaluated by computed tomography. We determined whether temporal changes in this antibody during therapy are associated with radiological responses.

RESULTS

Of the 83 patients in our study, 29 (35%) had elevated serum anti-p53 antibody levels before chemotherapy. Among these, antibody levels decreased in all 14 responders. In contrast, among those patients with elevated pretherapeutic serum anti-p53 antibody levels, 89% showed a paradoxical decrease in antibody levels and exhibited disease progression after chemotherapy. Moreover, serum anti-p53 antibody levels before and after chemotherapy were not associated with survival.

CONCLUSION

These results suggest that serum anti-p53 antibody levels are of limited value in the evaluation of responses to palliative chemotherapy in patients with colorectal cancer.

Proteomic mapping of p53 immunogenicity in pancreatic, ovarian, and breast cancers

PURPOSE

Mutations in TP53 induce autoantibody immune responses in a subset of cancer patients, which have been proposed as biomarkers for early detection. Here, we investigate the association of p53-specific autoantibodies with multiple tumor subtypes and determine the association with p53 mutation status and epitope specificity.

EXPERIMENTAL DESIGN

IgG p53 autoantibodies (p53-AAb), were quantified in 412 serum samples using a programmable ELISA assay from patients with serous ovarian, pancreatic adenocarcinoma, and breast cancer. To determine if patients generated mutation-specific autoantibodies we designed a panel of the most relevant 51 p53 point mutant proteins, to be displayed on custom programmable protein microarrays. To determine the epitope specificity we displayed 12 overlapping tiling fragments and 38 N- and C-terminal deletions spanning the length of the wild-type p53 protein.

RESULTS

We detected p53-AAb with sensitivities of 58.8% (ovarian), 22% (pancreatic), 32% (triple negative breast cancer), and 10.2% (HER2+ breast cancer) at 94% specificity. Sera with p53-AAb contained broadly reactive autoantibodies to 51 displayed p53 mutant proteins, demonstrating a polyclonal response to common epitopes. All p53-AAb displayed broad polyclonal immune response to both continuous and discontinuous epitopes at the N- and C-terminus as well as the DNA-binding domain.

CONCLUSION AND CLINICAL RELEVANCE

In this comprehensive analysis, mutations in tumor p53 induce strong, polyclonal autoantibodies with broadly reactive epitope specificity.

Short O-GalNAc glycans: regulation and role in tumor development and clinical perspectives

BACKGROUND

While the underlying causes of cancer are genetic modifications, changes in cellular states mediate cancer development. Tumor cells display markedly changed glycosylation states, of which the O-GalNAc glycans called the Tn and TF antigens are particularly common. How these antigens get over-expressed is not clear. The expression levels of glycosylation enzymes fail to explain it.

SCOPE OF REVIEW

We describe the regulation of O-GalNAc glycosylation initiation and extension with emphasis on the initiating enzymes ppGalNAcTs (GALNTs), and introduce the GALA pathway--a change in GALNTs compartmentation within the secretory pathway that regulates Tn levels. We discuss the roles of O-GalNAc glycans and GALNTs in tumorigenic processes and finally consider diagnostic and therapeutic perspectives.

MAJOR CONCLUSIONS

Contrary to a common hypothesis, short O-glycans in tumors are not the result of an incomplete glycosylation process but rather reveal the activation of regulatory pathways. Surprisingly, high Tn levels reveal a major shift in the O-glycoproteome rather than a shortening of O-glycans. These changes are driven by membrane trafficking events.

GENERAL SIGNIFICANCE

Many attempts to use O-glycans for biomarker, antibody and therapeutic vaccine development have been made, but suffer limitations including poor sensitivity and/or specificity that may in part derive from lack of a mechanistic understanding. Deciphering how short O-GalNAc glycans are regulated would open new perspectives to exploit this biology for therapeutic usage. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Prognostic Role of Serum Antibody Immunity to p53 Oncogenic Protein in Ovarian Cancer: A Systematic Review and a Meta-Analysis

Objective

Serum p53 autoantibodies (p53-AAbs) are the product of an endogenous immune response against p53 overexpression driven by the ovarian tumour. The p53-AAbs are detectable only in a subset of patients. To date, the evidence of an association between the presence of p53-AAbs and ovarian cancer outcomes has been poorly investigated.

Methods

A systematic literature search was performed to identify eligible studies investigating the association of serum p53-AAbs and overall survival (OS) and disease free survival (DFS). Associations between presence of serum p53-AAbs and baseline tumour characteristics were also evaluated. Pooled hazard ratios (HRs) and corresponding 95% confidence intervals (CI) were computed to estimate the prognostic impact of serum p53-AAbs. Heterogeneity between studies was assessed.

Results

A total of 583 patients (7 studies) for OS and 356 patients (4 studies) for DFS were included in the meta-analysis. Presence of p53-AAbs was not associated to OS (pooled uni- multivariate HR = 1.09; 95% CI: 0.55–2.16), and a large heterogeneity was found. When only multivariate HRs were pooled together (4 studies), presence of p53-AAbs was significantly associated to a better OS (pooled HR = 0.57; 95% CI: 0.40–0.81), and no significant heterogeneity was observed. A reduced DFS was associated to p53-AAbs (pooled uni- multivariate HR = 1.37; 95% CI: 0.83–2.25), though not significantly and with a moderate heterogeneity.

Conclusions

The prognostic significance of serum p53-AAbs in ovarian cancer was diverging according to uni or multivariate models used. Since the results of this work were based on only few investigations, large prospective studies are needed to better define the role of antibody immunity against p53.

Developments in Screening Tests and Strategies for Colorectal Cancer

BACKGROUND

Worldwide, colorectal cancer (CRC) is the third most common cancer in men and second most common in women. It is the fourth most common cause of cancer mortality. In the United States, CRC is the third most common cause of cancer and second most common cause of cancer mortality. Incidence and mortality rates have steadily fallen, primarily due to widespread screening.

METHODS

We conducted keyword searches on PubMed in four categories of CRC screening: stool, endoscopic, radiologic, and serum, as well as news searches in Medscape and Google News.

RESULTS

Colonoscopy is the gold standard for CRC screening and the most common method in the United States. Technological improvements continue to be made, including the promising "third-eye retroscope." Fecal occult blood remains widely used, particularly outside the United States. The first at-home screen, a fecal DNA screen, has also recently been approved. Radiological methods are effective but seldom used due to cost and other factors. Serum tests are largely experimental, although at least one is moving closer to market.

CONCLUSIONS

Colonoscopy is likely to remain the most popular screening modality for the immediate future, although its shortcomings will continue to spur innovation in a variety of modalities.

WITHDRAWN: Dual display bacteriophage as a platform for high sensitive detection of serum p53 antibodies in breast cancer patients

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Sensitive Multiplexed Quantitative Analysis of Autoantibodies to Cancer Antigens with Chemically S-Cationized Full-Length and Water-Soluble Denatured Proteins

Humoral immune responses against tumor-associated antigens (TAAs) or cancer/testis antigens (CTAs) aberrantly expressed in tumor cells are frequently observed in cancer patients. Recent clinical studies have elucidated that anticancer immune responses with increased levels of anti-TAA/CTA antibodies improve cancer survival rates. Thus, these antibody levels are promising biomarkers for diagnosing the efficiency of cancer immunotherapy. Full-length antigens are favored for detecting anti-TAA/CTA antibodies because candidate antigen proteins contain multiple epitopes throughout their structures. In this study, we developed a methodology to prepare purified water-soluble and full-length antigens by using cysteine sulfhydryl group cationization (S-cationization) chemistry. S-Cationized antigens can be prepared from bacterial inclusion bodies, and they exhibit improved protein solubility but preserved antigenicity. Anti-TAA/CTA antibodies detected in cancer patients appeared to recognize linear epitopes, as well as conformational epitopes, and because the frequency of cysteine side-residues on the epitope-paratope interface was low, any adverse effects of S-cationization were virtually negligible for antibody binding. Furthermore, S-cationized antigen-immobilized Luminex beads could be successfully used in highly sensitive quantitative-multiplexed assays. Indeed, patients with a more broadly induced serum anti-TAA/CTA antibody level showed improved progression-free survival after immunotherapy. The comprehensive anti-TAA/CTA assay system, which uses S-cationized full-length and water-soluble recombinant antigens, may be a useful diagnostic tool for assessing the efficiency of cancer immunotherapy.

Cancer serum biomarkers based on aberrant post-translational modifications of glycoproteins: Clinical value and discovery strategies

Due to the increase in life expectancy in the last decades, as well as changes in lifestyle, cancer has become one of the most common diseases both in developed and developing countries. Early detection remains the most promising approach to improve long-term survival of cancer patients and this may be achieved by efficient screening of biomarkers in biological fluids. Great efforts have been made to identify specific alterations during oncogenesis. Changes at the cellular glycosylation profiles are among such alterations. The "glycosylation machinery" of cells is affected by malignant transformation due to the altered expression of glycogens, leading to changes in glycan biosynthesis and diversity. Alterations in the post-translational modifications of proteins that occur in cancer result in the expression of antigenically distinct glycoproteins. Therefore, these aberrant and cancer-specific glycoproteins and the autoantibodies that are produced in response to their presence constitute targets for cancer biomarkers' search. Different strategies have been implemented for the discovery of cancer glycobiomarkers and are herein reviewed, along with their potentialities and limitations. Practical issues related with serum analysis are also addressed, as well as the challenges that this area faces in the near future.

Serum anti-p53 antibody as a tumour marker for colorectal cancer screening

A 60-year-old Japanese man presented to our hospital for further investigation of an elevated serum anti-p53 antibody level. He was diagnosed with colon cancer and the tumour was surgically resected. Histological diagnosis of advanced colon cancer without lymph node involvement or distant metastasis was made. It was noteworthy that both serum carcinoembryonic antigen (CEA) and a fecal occult blood test that were performed preoperatively were non-diagnostic. This case highlights the potential usefulness of serum anti-p53 antibody tests for detection of colorectal cancers. Moreover, sequential changes in the anti-p53 antibody levels after curative resection were observed.

Diagnostic potential of zinc finger protein-specific autoantibodies and associated linear B-cell epitopes in colorectal cancer

Colorectal cancer is one of the most common cancers worldwide with almost 700,000 deaths every year. Detection of colorectal cancer at an early stage significantly improves patient survival. Cancer-specific autoantibodies found in sera of cancer patients can be used for pre-symptomatic detection of the disease. In this study we assess the zinc finger proteins ZNF346, ZNF638, ZNF700 and ZNF768 as capture antigens for the detection of autoantibodies in colorectal cancer. Sera from 96 patients with colorectal cancer and 35 control patients with no evidence of cancer on colonoscopy were analysed for the presence of ZNF-specific autoantibodies using an indirect ELISA. Autoantibodies to individual ZNF proteins were detected in 10-20% of colorectal cancer patients and in 0-5.7% of controls. A panel of all four ZNF proteins resulted in an assay specificity of 91.4% and sensitivity of 41.7% for the detection of cancer patients in a cohort of non-cancer controls and colorectal cancer patients. Clinicopathological and survival analysis revealed that ZNF autoantibodies were independent of disease stage and did not correlate with disease outcome. Since ZNF autoantibodies were shared between patients and corresponding ZNF proteins showed similarities in their zinc finger motifs, we performed an in silico epitope sequence analysis. Zinc finger proteins ZNF700 and ZNF768 showed the highest sequence similarity with a bl2seq score of 262 (E-value 1E-81) and their classical C2H2 ZNF motifs were identified as potential epitopes contributing to their elevated immunogenic potential. Our findings show an enhanced and specific immunogenicity to zinc finger proteins, thereby providing a multiplexed autoantibody assay for minimally invasive detection of colorectal cancer.

Expression of Caspase3, P53 and Ki-67 in colon cancer and colon adenoma

AIM: To explore the expression of Caspase3, P53 and Ki-67 in colon cancer and colon adenoma.

METHODS: The expression of Caspase3, P53 and Ki-67 in 100 colon cancer tissues and 100 colon adenoma tissues was detected by immunohistochemistry. Correlations between Caspase3, P53 and Ki-67 expression and between their expression and clincopatholgical parameters were investigated using Spearman correlation analysis.

RESULTS: The expression of Caspase3, P53 and Ki-67 had no significant correlation with age, sex, tumor differentiation or infiltration (P > 0.05). The positive expression rates of Caspase3, P53 and Ki-67 differed significantly between the lymph node metastasis group (18.18%, 31.82%, and 90.91%, respectively) and non-lymph node metastasis group (52.56%, 89.74%, and 61.54%, respectively) and between Duke's stage A-B (52.56%, 89.74%, and 61.54%, respectively) and C-D (18.18%, 31.82%, and 90.91%, respectively) (P < 0.05). The positive expression rates of Caspase3, P53 and Ki-67 were 45.00%, 77.00% and 68.00%, respectively, in colon cancer tissues and 83.00%, 49.00% and 26.00%, respectively, in adenoma tissues (P < 0.01). The expression of P53 was positively correlated with that of Caspase3 (r = 0.315, P < 0.01), but negatively correlated with that of Ki-67 (r = -0.302, P < 0.01).

CONCLUSION: Caspase3, P53 and Ki-67 are all involved in the development and progression of colon cancer, and combined detection of their expression can help determine the invasion, metastasis and prognosis of this malignancy.

Serum autoantibody measurement for the detection of hepatocellular carcinoma

Background

Individuals with liver disease, and especially those with Hepatitis B or C, are at an increased risk of developing hepatocellular carcinoma (HCC) which is the third most common cause of cancer-related death worldwide. Inadequate screening tests largely account for presentation of advanced tumours and high mortality rates. Early detection of HCC amongst high-risk groups is paramount in improving prognosis. This research aimed to further characterise the previously described humoral immune response raised to tumour-associated antigens (TAAs) in the serum of patients with HCC.

Methods

Serum from 96 patients with confirmed HCC, 96 healthy controls matched for age and sex, 78 patients with confirmed liver cirrhosis and 91 patients with confirmed chronic liver disease were analysed for the presence of IgG autoantibodies raised to 41 recombinant TAAs/antigen fragments by ELISA.

Results

Varying autoantibody specificities (97–100%) and sensitivities (0–10%) were observed to individual TAAs. A 21-antigen panel achieved a specificity of 92% and sensitivity of 45% for the detection of HCC. This same panel identified 21% of 169 high-risk controls as having elevated autoantibody levels. A reproducible panel of 10 antigens achieved a specificity of 91% and sensitivity of 41% in HCC. 15% of 152 high-risk controls gave positive results with this panel.

Conclusions

This minimally invasive blood test has the potential to offer advantages over currently available tools for the identification of HCC amongst pre-disposed patients. Results are comparable to current gold standards in HCC (Ultrasonography) and to similar tests in other cancers (EarlyCDT-Lung).