Alzheimer's disease (AD) is the most common form of dementia in developed countries. A better understanding of the events taking place at the molecular level would help to identify novel protein alterations, which might be used in diagnosis or for treatment development. In this study, we have performed the high-throughput analysis of 706 molecules mostly implicated in cell-cell communication and cell signaling processes by using two antibody microarray platforms. We screened three AD pathological groups -each one containing four pooled samples- from Braak stages IV, V and VI, and three control groups from two healthy subjects, five frontotemporal and two vascular dementia patients onto Panorama and L-Series antibody microarrays to identify AD-specific alterations not common to other dementias. Forty altered proteins between control and AD groups were detected, and validated by i) meta-analysis of mRNA alterations, ii) WB, and iii) FISH and IHC using an AD-specific tissue microarray containing 44 samples from AD patients at different Braak stages, and frontotemporal and vascular dementia patients and healthy individuals as controls. We identified altered proteins in AD not common to other dementias like the E3 ubiquitin-protein ligase TOPORS, Layilin and MICB, and validated the association to AD of the previously controverted proteins DDIT3 and the E3 ubiquitin-protein ligase XIAP. These altered proteins constitute interesting targets for further immunological analyses using sera, plasma and CSF to identify AD blood- or cerebrospinal fluid-biomarkers and to perform functional analysis to determine their specific role in AD, and their usefulness as potential therapeutic targets of intervention.

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.

Nucleic acid-based analytical bioplatforms have gained importance as diagnostic tests for genomics and as early detection tools for diseases such as cancer. In this context, we report the development of an amperometric bioplatform for the determination of a specific human papillomavirus type 16 (HPV16) sequence. The bioplatform utilizes an immune-nucleic acid hybrid-sandwich assay. A biotinylated RNA capture probe (RNAbCp), complementary to the selected HPV16 target DNA sequence, was immobilised on the surface of streptavidin coated magnetic microbeads (Strep-MBs). The RNA/DNA heteroduplex resulting from the hybridization of the RNAbCP and the HPV16 target sequence was recognised by a commercial antibody that specifically bound to the heteroduplex (AbDNA-RNA). A horseradish-peroxide labeled secondary antibody (antiIgG-HRP) was used for the detection of AbDNA-RNA. Relying on amperometric detection of the resulting HRP-labeled magnetic bioconjugates captured on screen-printed electrodes (SPCEs) in the presence of H2O2 and hydroquinone (HQ), the biotool achieved a low limit of detection (0.5 pM) for the synthetic HPV16 target DNA. In addition, the developed bioplatform was able to discriminate between HPV16 positive and negative human cancer cells using only 25 ng of amplified DNA in a test time of 45 min.

An amperometric magnetoimmunosensor for the determination of human p53 protein is described in this work using a sandwich configuration involving the covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic beads (HOOC-MBs) and incubation of the modified MBs with a mixture of the target protein and horseradish peroxidase-labeled antibody (HRP-anti-p53). The resulting modified MBs are captured by a magnet placed under the surface of a disposable carbon screen-printed electrode (SPCE) and the amperometric responses are measured at -0.20 V (vs. an Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as a redox mediator and H₂O₂ as the enzyme substrate. The magnetoimmunosensing platform was successfully applied for the detection of p53 protein in different cell lysates without any matrix effect after a simple sample dilution. The results correlated accurately with those provided by a commercial ELISA kit, thus confirming the immunosensor as an attractive alternative for rapid and simple determination of this protein using portable and affordable instrumentation.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer related death worldwide. Its diagnosis at early stages would significantly improve the survival of CRC patients. The humoral immune response has been demonstrated useful for cancer diagnosis, predating clinical symptoms up to 3 years. Here, we employed an in-depth seroproteomic approach to identify proteins that elicit a humoral immune response in CRC patients. The seroproteomic approach relied on the immunoprecipitation with patient-derived autoantibodies of proteins from CRC cell lines with different metastatic properties followed by LC-MS/MS. After bioinformatics, we focused on 31 targets of CRC autoantibodies. After WB and IHC validation, ERP44 and TALDO1 showed potential to discriminate disease-free and metastatic CRC patients, and time to recurrence of CRC patients in stage II. Using plasma samples of 30 healthy individuals, 28 premalignant individuals, and 32 CRC patients, nine out of 13 selected targets for seroreactive analysis showed significant diagnostic ability to discriminate either CRC patients or premalignant subjects from controls. Our results suggest that the here defined panel of CRC autoantibodies and their target proteins should be included in CRC blood-based biomarker panels to get a clinically useful blood-based diagnostic signature for CRC detection. SIGNIFICANCE: Colorectal cancer is one of the deadliest cancer types mainly due to its late diagnosis. Its early diagnosis, therefore, is of great importance since it would significantly improve the survival of CRC patients. In our work, the in-depth seroproteomic analysis of colorectal cancer using isolated IgGs from colorectal cancer patients and controls and protein extract of colorectal cancer cells provide the identification of valuable biomarkers with diagnostic and prognostic ability of the disease.

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death worldwide. Alterations in proteins of the p53-family are a common event in CRC. ΔNp73, a p53-family member, shows oncogenic properties and its effectors are largely unknown. We performed an in-depth proteomics characterization of transcriptional control by ∆Np73 of the secretome of human colon cancer cells and validated its clinical potential. The secretome was analyzed using high-density antibody microarrays and stable isotopic metabolic labeling. Validation was performed by semiquantitative PCR, ELISA, dot-blot and western blot analysis. Evaluation of selected effectors was carried out using 60 plasma samples from CRC patients, individuals carrying premalignant colorectal lesions and colonoscopy-negative controls. In total, 51 dysregulated proteins were observed showing at least 1.5-foldchange in expression. We found an important association between the overexpression of ∆Np73 and effectors related to lymphangiogenesis, vasculogenesis and metastasis, such as brain-derived neurotrophic factor (BDNF) and the putative aminoacyl tRNA synthase complex-interacting multifunctional protein 1 (EMAP-II)-vascular endothelial growth factor C-vascular endothelial growth factor receptor 3 axis. We further demonstrated the usefulness of BDNF as a potential CRC biomarker able to discriminate between CRC patients and premalignant individuals from controls with high sensitivity and specificity.

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 constitute a powerful tool to study protein function, protein localization and protein-protein interactions, as well as for diagnostic and therapeutic purposes. High-throughput antibody development requires faster methodologies with lower antigen consumption.

Fibroblast growth factor receptor 4 (FGFR4) is vital in early development and tissue repair. FGFR4 expression levels are very restricted in adult tissues, except in several solid tumors including colorectal cancer, which showed overexpression of FGFR4. Here, FGFR4 mutation analysis discarded the presence of activating mutations, other than Arg(388), in different colorectal cancer cell lines and tumoral samples. Stable shRNA FGFR4-silencing in SW480 and SW48 cell lines resulted in a significant decrease in cell proliferation, adhesion, cell migration and invasion. This decrease in the tumorigenic and invasive capabilities of colorectal cancer cells was accompanied by a decrease of Snail, Twist and TGFβ gene expression levels and an increase of E-cadherin, causing a reversion to a more epithelial phenotype, in three different cell lines. In addition, FGFR4-signaling activated the oncogenic SRC, ERK1/2 and AKT pathways in colon cancer cells and promoted an increase in cell survival. The relevance of FGFR4 in tumor growth was supported by two different strategies. Kinase inhibitors abrogated FGFR4-related cell growth and signaling pathways at the same extent than FGFR4-silenced cells. Specific FGFR4-targeting using antibodies provoked a similar reduction in cell growth. Moreover, FGFR4 knock-down cells displayed a reduced capacity for in vivo tumor formation and angiogenesis in nude mice. Collectively, our data support a crucial role for FGFR4 in tumorigenesis, invasion and survival in colorectal cancer. In addition, FGFR4 targeting demonstrated its applicability for colorectal cancer therapy.

Although autoantibody detection has been proposed for diagnosis of colorectal cancer, little is known about their initial production and development correlation with cancer progression. Azoxymethane/dextran sodium sulfate (AOM/DSS)-treated mice developed colon adenocarcinoma in the distal colon similar to human sporadic colon cancer. We assessed this model together with AOM and DSS-only models for their applicability to early detection of cancer. All AOM/DSS-treated mice produced autoantibodies to tumor-associated antigens analogous to those observed in human colon cancer patients. Autoantibody response was related to tumor antigen overexpression. Cancer autoantibodies were detected 21 days after starting treatment, when no malignant histopathological features were detectable, and they increased according to tumor progression. When carcinogenesis was induced separately by AOM or DSS, only those mice that developed malignant lesions produced significant levels of autoantibodies. These findings demonstrate that autoantibody development is an early event in tumorigenesis and validates its use for preclinical colon cancer diagnosis.

A dual immunosensor is reported for the simultaneous determination of two important immunity-related cytokines: BAFF (B cell activation factor) and APRIL (a proliferation-induced signal). Sandwich-type immunoassays with specific antibodies (cAbs) and a strategy for signal amplification based on labelling the detection antibodies (dAbs) with binary MoS2/MWCNTs nanostructures and using horseradish peroxidase (HRP) were implemented. Amperometric detection was carried out at screen-printed dual carbon electrodes (SPdCEs) through the hydroquinone HQ/H2O2 system. The developed dual immunosensor provided limit of detection (LOD) of 0.08 and 0.06 ng mL-1 for BAFF and APRIL, respectively, and proved to be useful for the determination of both cytokines in cancer cell lysates and serum samples from patients diagnosed with autoimmune diseases and cancer. The obtained results agreed with those found using ELISA methodologies.

This paper describes two different electrochemical affinity biosensing approaches for the simple, fast and bisulfite and PCR-free quantification of 5-methylated cytosines (5-mC) in DNA using the anti-5-mC antibody as biorecognition element. One of the biosensing approaches used the anti-5-mC as capture bioreceptor and a sandwich type immunoassay, while the other one involved the use of a specific DNA probe and the anti-5-mC as a detector bioreceptor of the captured methylated DNA. Both strategies, named for simplicity in the text as immunosensor and DNA sensor, respectively, were implemented on the surface of magnetic microparticles and the transduction was accomplished by amperometry at screen-printed carbon electrodes by means of the hydrogen peroxide/hydroquinone system. The resulting amperometric biosensors demonstrated reproducibility throughout the entire protocol, sensitive determination with no need for using amplification strategies, and competitiveness with the conventional enzyme-linked immunosorbent assay methodology and the few electrochemical biosensors reported so far in terms of simplicity, sensitivity and assay time. The DNA sensor exhibited higher sensitivity and allowed the detection of the gene-specific methylations conversely to the immunosensor, which detected global DNA methylation. In addition, the DNA sensor demonstrated successful applicability for 1 h-analysis of specific methylation in two relevant tumor suppressor genes in spiked biological fluids and in genomic DNA extracted from human glioblastoma cells.

The first electrochemical immunosensor for the determination of fibroblast growth factor receptor 4 (FGFR4) biomarker is reported in this work. The biosensor involves a sandwich configuration with covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic microcarriers (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs). The biosensor exhibits a great analytical performance regarding selectivity for the target protein and a low LOD of 48.2 pg mL-1. The electrochemical platform was successfully applied for the determination of FGFR4 in different cancer cell lysates without any apparent matrix effect after a simple sample dilution and using only 2.5 μg of the raw lysate. Comparison of the results with those provided by a commercial ELISA kit shows competitive advantages by using the developed immunosensor in terms of simplicity, analysis time, and portability and cost-affordability of the required instrumentation for the accurate determination of FGFR4 in cell lysates.

Low-grade, early-stage endometrial carcinoma (EC) is the most frequent malignant tumor of the uterine corpus. However, the molecular alterations that underlie these tumors are far from being fully understood. The purpose of this study is to describe dysregulated molecular pathways from EC patients. Sixteen samples of tumor tissue and paired healthy controls were collected and both were subjected to mass spectrometry (MS)/MS proteomic analysis. Gene ontology and pathway analysis was performed to discover dysregulated pathways and/or proteins using different databases and bioinformatic tools. Dysregulated pathways were cross-validated in an independent external cohort. Cell signaling, immune response, and cell death-associated pathways were robustly identified. The SLIT/ROBO signaling pathway demonstrated dysregulation at the proteomic and transcriptomic level. Necroptosis and ferroptosis were cell death-associated processes aberrantly regulated, in addition to apoptosis. Immune response-associated pathways showed a dominance of innate immune responses. Tumor immune infiltrates measured by immunofluorescence demonstrated diverse lymphoid and myeloid populations. Our results suggest a role of SLIT/ROBO, necroptosis, and ferroptosis, as well as a prominent role of innate immune response in low-grade, early-stage EC. These results could guide future research in this group of tumors.

Olive pollen is a major cause of immunoglobulin E (IgE)-mediated allergy in Mediterranean countries. It is expected to become a worldwide leading allergenic source because olive cultivation is increasing in many countries. Ole e 15 belongs to the cyclophilin pan-allergen family, which includes highly cross-reactive allergens from non-related plant, animal and mold species. Here, the amino acid differences between Ole e 15 and its weak cross-reactive human homolog PPIA were grafted onto Ole e 15 to assess the contribution of specific surface areas to the IgE-binding. Eight Ole e 15-PPIA chimeras were produced in E. coli, purified and tested with 20 sera from Ole e 15-sensitized patients with olive pollen allergy by ELISA experiments. The contribution of linear epitopes was analyzed using twelve overlapping peptides spanning the entire Ole e 15 sequence. All the patients displayed a diverse reduction of the IgE-reactivity to the chimeras, revealing a highly polyclonal and patient-specific response to Ole e 15. IgE-epitopes are distributed across the entire Ole e 15 surface. Two main surface areas containing relevant conformational epitopes have been characterized. This is the first study to identify important IgE-binding regions on the surface of an allergenic cyclophilin.

Spry2 is a molecular modulator of tyrosine kinase receptor signaling pathways that has cancer-type-specific effects. Mammalian Spry2 protein undergoes tyrosine and serine phosphorylation in response to growth factor stimulation. Spry2 expression is distinctly altered in various cancer types. Inhibition of the proteasome functionality results in reduced intracellular Spry2 degradation. Using in vitro and in vivo assays, we show that protein kinase D (PKD) phosphorylates Spry2 at serine 112 and interacts in vivo with the C-terminal half of this protein. Importantly, missense mutation of Ser112 decreases the rate of Spry2 intracellular protein degradation. Either knocking down the expression of all three mammalian PKD isoforms or blocking their kinase activity with a specific inhibitor contributes to the stabilization of Spry2 wild-type protein. Downregulation of CSN3, a component of the COP9/Signalosome that binds PKD, significantly increases the half-life of Spry2 wild-type protein but does not affect the stability of a Spry2 after mutating Ser112 to the non-phosphorylatable residue alanine. Our data demonstrate that both PKD and the COP9/Signalosome play a significant role in control of Spry2 intracellular stability and support the consideration of the PKD/COP9 complex as a potential therapeutic target in tumors where Spry2 expression is reduced.

Clathrin assembles at the cells' plasma membrane in a multitude of clathrin-coated structures (CCSs). Among these are flat clathrin lattices (FCLs), alternative clathrin structures that have been found in specific cell types, including cancer cells. Here we show that these structures are also present in different colorectal cancer (CRC) cell lines, and that they are extremely stable with lifetimes longer than 8 h. By combining cell models representative of CRC metastasis with advanced fluorescence imaging and analysis, we discovered that the metastatic potential of CRC is associated with an aberrant membranous clathrin distribution, resulting in a higher prevalence of FCLs in cells with a higher metastatic potential. These findings suggest that clathrin organization might play an important yet unexplored role in cancer metastasis.

The glycosylation status of proteins is increasingly used as biomarker to improve the reliability in the diagnosis and prognosis of diseases as relevant as cancer. This feeds the need for tools that allow its simple and reliable analysis and are compatible with applicability in the clinic. With this objective in mind, this work reports the first bioelectronic immunoplatforms described to date for the determination of glycosylated haptoglobin (Hp) and the simultaneous determination of total and glycosylated Hp. The bioelectronic immunoplatform is based on the implementation of non-competitive bioassays using two different antibodies or an antibody and a lectin on the surface of commercial magnetic microcarriers. The resulting bioconjugates are labeled with the horseradish peroxidase (HRP) enzyme, and after their magnetic capture on disposable electroplatforms, the amperometric transduction using the H2O2/hydroquinone (HQ) system allows the single or multiple detection. The developed immunoplatform achieves limits of detection (LODs) of 0.07 and 0.46 ng mL-1 for total and glycosylated Hp in buffer solution, respectively. The immunoplatform allows accurate determination using simple and relatively short protocols (approx. 75 min) of total and glycosylated Hp in the secretomes of in vitro-cultured colorectal cancer (CRC) cells with different metastatic potentials, which is not feasible, due to lack of sensitivity, by means of some commercial ELISA kits and Western blot methodology.

Endometrial cancer (EC) is the most common cancer of the female reproductive organs. Despite the good overall prognosis of most low-grade ECs, FIGO I and FIGO II patients might experience tumor recurrence and worse prognosis. The study of alterations related to EC pathogenesis might help to get insights into underlying mechanisms involved in EC development and progression.

The proteome characterization of complex, deteriorated, or cross-linked protein mixtures as paired clinical FFPE or exosome samples isolated from low plasma volumes (250 µL) might be a challenge. In this work, we aimed at investigating the benefits of FAIMS technology coupled to the Orbitrap Exploris 480 mass spectrometer for the TMT quantitative proteomics analyses of these complex samples in comparison to the analysis of protein extracts from cells, frozen tissue, and exosomes isolated from large volume plasma samples (3 mL). TMT experiments were performed using a two-hour gradient LC-MS/MS with or without FAIMS and two compensation voltages (CV = -45 and CV = -60). In the TMT experiments of cells, frozen tissue, or exosomes isolated from large plasma volumes (3 mL) with FAIMS, a limited increase in the number of identified and quantified proteins accompanied by a decrease in the number of peptides identified and quantified was observed. However, we demonstrated here a noticeable improvement (>100%) in the number of peptide and protein identifications and quantifications for the plasma exosomes isolated from low plasma volumes (250 µL) and FFPE tissue samples in TMT experiments with FAIMS in comparison to the LC-MS/MS analysis without FAIMS. Our results highlight the potential of mass spectrometry analyses with FAIMS to increase the depth into the proteome of complex samples derived from deteriorated, cross-linked samples and/or those where the material was scarce, such as FFPE and plasma-derived exosomes from low plasma volumes (250 µL), which might aid in the characterization of their proteome and proteoforms and in the identification of dysregulated proteins that could be used as biomarkers.