Serum anti-LRPAP1 is a common biomarker for digestive organ cancers and atherosclerotic diseases

Proteome-Wide Mendelian Randomization Analysis to Identify Potential Plasma Biomarkers and Therapeutic Targets for Epithelial Ovarian Cancer Subtypes

Background

Epithelial ovarian cancer (EOC) remains an unmet medical challenge due to its insidious onset, atypical symptoms, and increasing resistance to conventional chemotherapeutic agents. It is imperative to explore novel biomarkers and generate innovative target drugs.

Methods

To identify potential proteins with causal association to EOC subtypes, we conducted a Mendelian Randomization (MR) analysis using 15,419 protein quantitative trait loci (pQTLs) associated with 2015 proteins. Bayesian colocalization analysis, Summary-data-based MR, and Heterogeneity in Dependent Instruments tests were employed for validation. Enrichment and druggability analyses were performed to assess the biological significance and therapeutic potential of identified proteins.

Results

Our analysis identified 455 unique proteins associated with at least one EOC subtype, with 14 protein-cancer associations confirmed by further validation. Ten proteins were prioritized as potential therapeutic targets, including α1B-glycoprotein (A1BG) and ephrin-A1 (EFNA1), which interact with the known drug targets human epidermal growth factor receptor 2 (HER2) and vascular endothelial growth factor receptor (VEGFR).

Conclusion

This study elucidated the plasma proteins causally associated with EOC subtypes, potentially offering easily detectable biomarkers and promising therapeutic targets. A1BG and EFNA1 were identified as druggable targets and confirmed to correspond with current pharmacological targets. Targeting these proteins in drug development potentially offers an avenue for innovative treatment strategies.

Serum anti‑KIAA0513 antibody as a common biomarker for mortal atherosclerotic and cancerous diseases

Numerous antibody biomarkers have been reported for cancer and atherosclerosis-related diseases. The major complications of atherosclerosis and diabetes mellitus (DM) are acute ischemic stroke (AIS), cardiovascular disease (CVD) and chronic kidney disease (CKD). Cancer development is accompanied by arterial disorders, such as angiogenesis and atherosclerosis, and DM is a risk factor for the development of certain types of cancer. Atherosclerosis-related diseases and cancers are therefore interrelated and could be detected using a common biomarker. In the present study, the initial screening using the protein array method identified KIAA0513 as an antigen recognized by serum IgG antibodies in patients with atherosclerosis. The amplified luminescent proximity homogeneous assay-linked immunosorbent assay revealed significantly higher serum antibody levels against recombinant KIAA0513 protein in patients with AIS, transient ischemic attack (TIA), DM, CVD, obstructive sleep apnea syndrome (OSAS), CKD and solid cancers, such as esophageal, gastric, colon, lung and breast cancers, compared with healthy donors. A receiver operating characteristic (ROC) analysis revealed that the highest areas under the ROC curves of anti-KIAA0513 antibodies were obtained for esophageal cancer, nephrosclerosis-type CKD and DM. Spearman's correlation analysis revealed that serum anti-KIAA0513 antibody levels were associated with maximum intima-media thickness and plaque score, which are indices of atherosclerosis and stenosis. Serum anti-KIAA0513 antibody markers appear to be useful for diagnosing AIS, TIA, DM, CVD, OSAS, CKD and solid cancers, and may reflect common arterial alterations leading to atherosclerotic and cancerous diseases.

Combination of high anti-SKI and low anti-TMED5 antibody levels is preferable prognostic factor in esophageal carcinoma

Given that esophageal cancer is highly malignant, the discovery of novel prognostic markers is eagerly awaited. We performed serological identification of antigens by recombinant cDNA expression cloning (SEREX) and identified SKI proto-oncogene protein and transmembrane p24 trafficking protein 5 (TMED5) as antigens recognized by serum IgG antibodies in patients with esophageal carcinoma. SKI and TMED5 proteins were expressed in Escherichia coli, purified by affinity chromatography, and used as antigens. The serum anti-SKI antibody (s-SKI-Ab) and anti-TMED5 antibody (s-TMED5-Ab) levels were significantly higher in 192 patients with esophageal carcinoma than in 96 healthy donors. The presence of s-SKI-Abs and s-TMED5-Abs in the patients' sera was confirmed by western blotting. Immunohistochemical staining showed that the TMED5 protein was highly expressed in the cytoplasm and nuclear compartments of the esophageal squamous cell carcinoma tissues, whereas the SKI protein was localized predominantly in the nuclei. Regarding the overall survival in 91 patients who underwent radical surgery, the s-SKI-Ab-positive and s-TMED5-Ab-negative statuses were significantly associated with a favorable prognosis. Additionally, the combination of s-SKI-Ab-positive and s-TMED5-Ab-negative cases showed an even clearer difference in overall survival as compared with that of s-SKI-Ab-negative and s-TMED5-Ab-positive cases. The s-SKI-Ab and s-TMED5-Ab biomarkers are useful for diagnosing esophageal carcinoma and distinguishing between favorable and poor prognoses.

Stage-Specific Alteration and Prognostic Relationship of Serum Fumarate Hydratase Autoantibodies in Gastric Cancer

The relationship between energy production and cancer is attracting attention. This study aimed to investigate the clinicopathological significance of fumarate hydratase (FH), a tricarboxylic acid cycle enzyme, in gastric cancer using autoantibodies as biomarkers. The study analyzed 116 patients who underwent gastric cancer surgery and 96 healthy controls. Preoperative serum FH autoantibody (s-FH-Ab) titers were analyzed using an immunosorbent assay with an amplified luminescent proximity homogeneous assay. Receiver operating characteristic analysis was used to determine the cutoff s-FH-Ab titer. Clinicopathological factors and prognosis were compared between the high and low s-FH-Ab groups. The s-FH-Ab levels were significantly higher in the gastric cancer group than in the control group (p = 0.01). Levels were elevated even in patients with stage I gastric cancer compared with healthy controls (p = 0.02). A low s-FH-Ab level was significantly associated with distant metastasis (p = 0.01), peritoneal dissemination (p < 0.05), and poor overall survival (p < 0.01). Multivariate analysis revealed that low s-FH-Ab levels were an independent risk factor for poor prognosis (p < 0.01). Therefore, s-FH-Ab levels may be a useful biomarker for early diagnosis and the prediction of prognosis in patients with gastric cancer.

Atherosclerosis-related biomarker PABPC1 predicts pan-cancer events

BACKGROUND

Atherosclerosis (AS) and tumours are the leading causes of death worldwide and share common risk factors, detection methods and molecular markers. Therefore, searching for serum markers shared by AS and tumours is beneficial to the early diagnosis of patients.

METHODS

The sera of 23 patients with AS-related transient ischaemic attack were screened by serological identification of antigens through recombinant cDNA expression cloning (SEREX), and cDNA clones were identified. Pathway function enrichment analysis was performed on cDNA clones to identify their biological pathways and determine whether they were related to AS or tumours. Subsequently, gene-gene and protein-protein interactions were performed and AS-associated markers would be discovered. The expression of AS biomarkers in human normal organs and pan-cancer tumour tissues were explored. Then, immune infiltration level and tumour mutation burden of various immune cells were evaluated. Survival curves analysis could show the expression of AS markers in pan-cancer.

RESULTS

AS-related sera were screened by SEREX, and 83 cDNA clones with high homology were obtained. Through functional enrichment analysis, it was found that their functions were closely related to AS and tumour functions. After multiple biological information interaction screening and the external cohort validating, poly(A) binding protein cytoplasmic 1 (PABPC1) was found to be a potential AS biomarker. To assess whether PABPC1 was related to pan-cancer, its expression in different tumour pathological stages and ages was screened. Since AS-associated proteins were closely related to cancer immune infiltration, we investigated and found that PABPC1 had the same role in pan-cancer. Finally, analysis of Kaplan-Meier survival curves revealed that high PABPC1 expression in pan-cancer was associated with high risk of death.

CONCLUSIONS

Through the findings of SEREX and bioinformatics pan-cancer analysis, we concluded that PABPC1 might serve as a potential biomarker for the prediction and diagnosis of AS and pan-cancer.

Proteomic analysis reveals LRPAP1 as a key player in the micropapillary pattern metastasis of lung adenocarcinoma

Objectives

Lung adenocarcinomas have different prognoses depending on their histological growth patterns. Micropapillary growth within lung adenocarcinoma, particularly metastasis, is related to dismal prognostic outcome. Metastasis accounts for a major factor leading to mortality among lung cancer patients. Understanding the mechanisms underlying early stage metastasis can help develop novel treatments for improving patient survival.

Methods

Here, quantitative mass spectrometry was conducted for comparing protein expression profiles among various histological subtypes, including adenocarcinoma in situ, minimally invasive adenocarcinoma, and invasive adenocarcinoma (including acinar and micropapillary [MIP] types). To determine the mechanism of MIP-associated metastasis, we identified a protein that was highly expressed in MIP. The expression of the selected highly expressed MIP protein was verified via immunohistochemical (IHC) analysis and its function was validated by an in vitro migration assay.

Results

Proteomic data revealed that low-density lipoprotein receptor-related protein-associated protein 1 (LRPAP1) was highly expressed in MIP group, which was confirmed by IHC. The co-expressed proteins in this study, PSMD1 and HSP90AB1, have been reported to be highly expressed in different cancers and play an essential role in metastasis. We observed that LRPAP1 promoted lung cancer progression, including metastasis, invasion and proliferation in vitro and in vivo.

Conclusion

LRPAP1 is necessary for MIP-associated metastasis and is the candidate novel anti-metastasis therapeutic target.

Serum anti-PCK1 antibody levels are a prognostic factor for patients with diabetes mellitus

BACKGROUND

Autoantibodies develop in autoimmune diseases, cancer, diabetes mellitus (DM), and atherosclerosis-related diseases. However, autoantibody biomarkers have not been successfully examined for diagnosis and therapy.

METHODS

Serological identification of antigens through recombinant cDNA expression cloning (SEREX) was used for primary screening of antigens. The cDNA product was expressed in bacteria and purified. Amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) was used to evaluate antibody levels in serum samples.

RESULTS

Phosphoenolpyruvate carboxykinase 1 (PCK1) was recognized as an antigen by serum IgG antibodies in the sera of patients with atherosclerosis. AlphaLISA showed significantly higher serum antibody levels against recombinant PCK1 protein in patients with DM and cardiovascular disease than in healthy donors, but not in those with acute ischemic stroke, transient ischemic attack, or obstructive sleep apnea syndrome. The area under the receiver operating characteristic curve for anti-PCK1 antibodies was 0.7024 for DM. The serum anti-PCK1 antibody levels were associated with age, platelet count, and blood pressure. Anti-PCK1-antibody-positive patients showed significantly lower overall survival than the negative patients.

CONCLUSIONS

Serum anti-PCK1 antibody levels were found to be associated with DM. The anti-PCK1 antibody marker is useful for predicting the overall survival of patients with DM.

The combination of positive anti‑WDR1 antibodies with negative anti‑CFL1 antibodies in serum is a poor prognostic factor for patients with esophageal carcinoma

WD repeat-containing protein 1 (WDR1) regulates the cofilin 1 (CFL1) activity, promotes cytoskeleton remodeling, and thus, facilitates cell migration and invasion. A previous study reported that autoantibodies against CFL1 and β-actin were useful biomarkers for diagnosing and predicting the prognosis of patients with esophageal carcinoma. Therefore, the present study aimed to evaluate the serum levels of anti-WDR1 antibodies (s-WDR1-Abs) combined with serum levels of anti-CFL1 antibodies (s-CFL1-Abs) in patients with esophageal carcinoma. Serum samples obtained from 192 patients with esophageal carcinoma and other solid cancers. And s-WDR1-Ab and s-CFL1-Ab titers were analyzed using the amplified luminescent proximity homogeneous assay-linked immunosorbent assay. Compared with those of healthy donors, the s-WDR1-Ab levels were significantly higher in the 192 patients with esophageal, whereas these were not significantly higher in the samples from patients with gastric, colorectal, lung, or breast cancer. In 91 patients treated with surgery, sex, tumor depth, lymph node metastasis, stage and C-reactive protein levels were significantly associated with overall survival, as determined using the log-rank test, whereas the squamous cell carcinoma antigen, p53 antibody and s-WDR1-Ab levels tended to be associated with a worse prognosis. Although no significant difference was observed in the survival between the positive and negative groups of s-WDR1-Abs or s-CFL1-Abs alone in the Kaplan-Meier test, the patients in the s-WDR1-Ab-positive and s-CFL1-Ab-negative groups exhibited a significantly poorer prognosis in the overall survival analysis. On the whole, the present study demonstrates that the combination of positive anti-WDR1 antibodies with negative anti-CFL1 antibodies in serum may be a poor prognostic factor for patients with esophageal carcinoma.

Prognostic and diagnostic significance of preoperative Jumonji domain‑containing 6 antibodies in colorectal cancer

Jumonji domain-containing 6 (JMJD6) protein has been reported to be upregulated in different cancer cells; however, to the best of our knowledge, no report has analyzed serum anti-JMJD6 antibodies (s-JMJD6-Abs) in patients with cancer. Therefore, the present study evaluated the clinical significance of s-JMJD6-Abs in patients with colorectal cancer. Preoperative serum samples were analyzed from 167 patients with colorectal cancer who underwent radical surgery between April 2007 and May 2012. The pathological stages were as follows Stage I (n=47), stage II (n=56), stage III (n=49) and stage IV (n=15). In addition, 96 healthy participants were analyzed as controls. s-JMJD6-Abs were analyzed by amplified luminescent proximity homology assay-linked immunosorbent assay. The cutoff value of s-JMJD6-Abs for detecting colorectal cancer was calculated to be 5,720 using the receiver operating characteristic curve. The positive rate of s-JMJD6-Abs was 37% in patients with colorectal cancer (61 of 167), independent of carcinoembryonic antigen or carbohydrate antigen 19-9 and p53-Abs. Clinicopathological factors and prognosis were compared between the s-JMJD6-Abs-positive group and the s-JMJD6-Abs-negative group. The s-JMJD6-Ab-positive status was significantly associated with older age (P=0.03), but was not associated with other clinicopathological variables. Regarding recurrence-free survival, the s-JMJD6-positive status was a significant poor prognostic factor in both univariate (P=0.02) and multivariate (P<0.01) analyses. Similarly, regarding overall survival, the s-JMJD6-Abs-positive status was a significant poor prognostic factor in both univariate (P=0.03) and multivariate (P=0.01) analyses. In conclusion, preoperative s-JMJD6-Abs was positive in 37% of patients with colorectal cancer and may be considered an independent poor prognostic biomarker.

Low anti-CFL1 antibody with high anti-ACTB antibody is a poor prognostic factor in esophageal squamous cell carcinoma

BACKGROUND

Cofilin (CFL1, actin-binding protein) and β-actin (ACTB) are key molecules in the polymerization and depolymerization of actin microfilaments. The levels of these antibodies were analyzed, and the clinicopathological significance in patients with esophageal carcinoma were evaluated.

METHODS

The levels of anti-CFL1 and anti-ACTB antibodies were analyzed in serum samples of patients with esophageal carcinoma and of healthy donors. Eighty-seven cases underwent radical surgery and the clinicopathological characteristics and prognosis was examined.

RESULTS

Serum anti-CFL1 antibody (s-CFL1-Ab) levels and anti-ACTB antibody (s-ACTB-Ab) levels were significantly higher in patients with esophageal carcinoma than in healthy donors. Following the receiver operating characteristic curve analysis between healthy donors and esophageal carcinoma, the sensitivity and specificity for serum anti-CFL1 antibody (s-CFL1-Ab) were 53.3% and 68.8%. The sensitivity and specificity for serum anti-ACTB antibody (s-ACTB-Ab) were 54.9% and 67.7%, respectively. Univariate and multivariate analysis showed that s-CFL1-Ab and s-ACTB-Ab levels were not associated with sex, age, tumor depth, lymph node metastasis, or anti-p53-antibody levels. s-ACTB-Ab levels but not s-CFL1-Ab levels significantly correlated with squamous cell carcinoma antigen. Neither s-CFL1-Ab nor s-ACTB-Ab levels alone were obviously related to overall survival. However, patients with low s-CFL1-Ab levels and high s-ACTB-Ab levels exhibited significantly more unfavorable prognoses than those with high s-CFL1-Ab and low s-ACTB-Ab levels.

CONCLUSIONS

Serum levels of anti-CFL1 and anti-ACTB antibodies were significantly higher in patients with esophageal carcinoma than in healthy donors. A combination of low anti-CFL1 and high anti-ACTB antibodies is a poor prognostic factor in esophageal carcinoma.

Serum Anti-BRAT1 is a Common Molecular Biomarker for Gastrointestinal Cancers and Atherosclerosis

Atherosclerosis (AS) and cancers are major global causes of mortality and morbidity. They also share common modifiable pathogenesis risk factors. As the same strategies used to predict AS could also detect certain cancers, we sought novel serum antibody biomarkers of cancers in atherosclerotic sera sampled by liquid biopsy. Using serological antigen identification by cDNA expression cloning (SEREX) and western blot, we screened and detected the antigens BRCA1-Associated ATM Activator 1 (BRAT1) and WD Repeat Domain 1 (WDR1) in the sera of patients with transient ischemic attacks (TIA). Amplified luminescence proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) established the upregulation of serum BRAT1 antibody (BRAT1-Abs) and WDR1 antibody (WDR1-Abs) in patients with AS-related diseases compared with healthy subjects. ROC and Spearman’s correlation analyses showed that BRAT1-Abs and WDR1-Abs could detect AS-related diseases. Thus, serum BRAT1-Abs and WDR1-Abs are potential AS biomarkers. We used online databases and AlphaLISA detection to compare relative antigen and serum antibody expression and found high BRAT1 and BRAT1-Abs expression in patients with GI cancers. Significant increases (> 0.6) in the AUC for BRAT1-Ab vs. esophageal squamous cell carcinoma (ESCC), gastric cancer, and colorectal cancer suggested that BRAT1-Ab exhibited better predictive potential for GI cancers than WDR1-Ab. There was no significant difference in overall survival (OS) between BRAT1-Ab groups (P = 0.12). Nevertheless, a log-rank test disclosed that the highest serum BRAT1-Ab levels were associated with poor ESCC prognosis at 5–60 weeks post-surgery. We validated the foregoing conclusions by comparing serum BRAT1-Ab and WDR1-Ab levels based on the clinicopathological characteristics of the patients with ESCC. Multiple statistical approaches established a correlation between serum BRAT1-Ab levels and platelet counts. BRAT1-Ab upregulation may enable early detection of AS and GI cancers and facilitate the delay of disease progression. Thus, BRAT1-Ab is a potential antibody biomarker for the diagnosis of AS and GI cancers and strongly supports the routine clinical application of liquid biopsy in chronic disease detection and diagnosis.

Aorta Regulatory T Cells with a Tissue-Specific Phenotype and Function Promote Tissue Repair through Tff1 in Abdominal Aortic Aneurysms

In addition to maintaining immune tolerance, Foxp3⁺ regulatory T cells (Tregs) perform specialized functions in tissue homeostasis and remodeling. However, whether Tregs in aortic aneurysms have a tissue-specific phenotype and function is unclear. Here, a special group of Tregs that potentially inhibit abdominal aortic aneurysm (AAA) progression are identified and functionally characterized. Aortic Tregs gradually increase during the process of AAA and are mainly recruited from peripheral circulation. Single-cell TCR sequencing and bulk RNA sequencing demonstrate their unique phenotype and highly expressed trefoil factor 1 (Tff1). Foxp3^cre/cre Tff1^flox/flox mice are used to clarify the role of Tff1 in AAA, suggesting that aortic Tregs secrete Tff1 to regulate smooth muscle cell (SMC) survival. In vitro experiments confirm that Tff1 inhibits SMC apoptosis through the extracellular signal-regulated kinase (ERK) 1/2 pathway. The findings reveal a tissue-specific phenotype and function of aortic Tregs and may provide a promising and novel approach for the prevention of AAA.

Association of Serum Anti-PCSK9 Antibody Levels with Favorable Postoperative Prognosis in Esophageal Cancer

Background

Esophageal cancer often appears as postoperative metastasis or recurrence after radical surgery. Although we had previously reported that serum programmed cell death ligand 1 (PD-L1) level correlated with the prognosis of esophageal cancer, further novel biomarkers are required for more precise prediction of the prognosis. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with the cholesterol metabolism. But there was no report of relationship between serum PCSK9 antibody and cancer. Therefore, we investigated whether anti-PCSK9 antibodies could be a novel biomarker for solid cancer.

Methods

Serum levels of anti-PCSK9 antibodies and antigens in patients with solid cancer were analyzed using amplified luminescence proximity homogeneous assay-linked immunosorbent assay (AlphaLISA). The reactivity of serum antibodies against recombinant PCSK9 protein was investigated by Western blotting, and the expression of PCSK9 antigens in esophageal cancer tissues was examined by immunohistochemical staining.

Results

AlphaLISA showed that serum anti-PCSK9 antibody (s-PCSK9-Ab) levels were significantly higher in patients with esophageal cancer, gastric cancer, colorectal cancer, lung cancer, and breast cancer than in healthy donors, and patients with esophageal cancer had the highest levels. The presence of serum antibody in patients was confirmed by Western blotting. There was no apparent correlation between s-PCSK9-Ab and PCSK9 antigen levels. Immunohistochemical staining demonstrated the expression of PCSK9 antigen in both the cytoplasm and nuclear compartments of esophageal squamous cell carcinoma tissue but not in normal tissue. Compared with patients with low s-PCSK9-Ab levels, those with high s-PCSK9-Ab levels had a favorable postoperative prognosis after radical surgery for esophageal cancer. In the multivariate analysis, tumor depth and s-PCSK9-Ab level were identified as independent prognostic factors. In the univariate analysis of clinicopathological features, high PCSK9 antibody levels were not associated with sex, age, location, tumor depth, lymph node status, squamous cell carcinoma antigen, or p53-Ab, whereas they correlated significantly with PD-L1 levels, which were associated with unfavorable prognosis. Correlation between s-PCSK9-Ab and PD-L1 levels was also confirmed in the logistic regression analysis; therefore, low s-PCSK9-Ab levels could discriminate another poor prognosis group other than high-PD-L1 group.

Conclusions

Patients with solid cancer had higher s-PCSK9-Ab levels than healthy donors. High s-PCSK9-Ab levels indicated better prognosis for overall survival after surgery in patients with esophageal cancer.

Serum anti-AP3D1 antibodies are risk factors for acute ischemic stroke related with atherosclerosis

Atherosclerosis has been considered as the main cause of morbidity, mortality, and disability worldwide. The first screening for antigen markers was conducted using the serological identification of antigens by recombinant cDNA expression cloning, which has identified adaptor-related protein complex 3 subunit delta 1 (AP3D1) as an antigen recognized by serum IgG antibodies of patients with atherosclerosis. Serum antibody levels were examined using the amplified luminescent proximity homogeneous assay-linked immunosorbent assay (AlphaLISA) using a recombinant protein as an antigen. It was determined that the serum antibody levels against AP3D1 were higher in patients with acute ischemic stroke (AIS), transient ischemic attack, diabetes mellitus (DM), cardiovascular disease, chronic kidney disease (CKD), esophageal squamous cell carcinoma (ESCC), and colorectal carcinoma than those in the healthy donors. The area under the curve values of DM, nephrosclerosis type of CKD, and ESCC calculated using receiver operating characteristic curve analysis were higher than those of other diseases. Correlation analysis showed that the anti-AP3D1 antibody levels were highly associated with maximum intima-media thickness, which indicates that this marker reflected the development of atherosclerosis. The results of the Japan Public Health Center-based Prospective Study indicated that this antibody marker is deemed useful as risk factors for AIS.

Serum anti-DIDO1, anti-CPSF2, and anti-FOXJ2 antibodies as predictive risk markers for acute ischemic stroke

BACKGROUND

Acute ischemic stroke (AIS) is a serious cause of mortality and disability. AIS is a serious cause of mortality and disability. Early diagnosis of atherosclerosis, which is the major cause of AIS, allows therapeutic intervention before the onset, leading to prevention of AIS.

METHODS

Serological identification by cDNA expression cDNA libraries and the protein array method were used for the screening of antigens recognized by serum IgG antibodies in patients with atherosclerosis. Recombinant proteins or synthetic peptides derived from candidate antigens were used as antigens to compare serum IgG levels between healthy donors (HDs) and patients with atherosclerosis-related disease using the amplified luminescent proximity homogeneous assay-linked immunosorbent assay.

RESULTS

The first screening using the protein array method identified death-inducer obliterator 1 (DIDO1), forkhead box J2 (FOXJ2), and cleavage and polyadenylation specificity factor (CPSF2) as the target antigens of serum IgG antibodies in patients with AIS. Then, we prepared various antigens including glutathione S-transferase-fused DIDO1 protein as well as peptides of the amino acids 297-311 of DIDO1, 426-440 of FOXJ2, and 607-621 of CPSF2 to examine serum antibody levels. Compared with HDs, a significant increase in antibody levels of the DIDO1 protein and peptide in patients with AIS, transient ischemic attack (TIA), and chronic kidney disease (CKD) but not in those with acute myocardial infarction and diabetes mellitus (DM). Serum anti-FOXJ2 antibody levels were elevated in most patients with atherosclerosis-related diseases, whereas serum anti-CPSF2 antibody levels were associated with AIS, TIA, and DM. Receiver operating characteristic curves showed that serum DIDO1 antibody levels were highly associated with CKD, and correlation analysis revealed that serum anti-FOXJ2 antibody levels were associated with hypertension. A prospective case-control study on ischemic stroke verified that the serum antibody levels of the DIDO1 protein and DIDO1, FOXJ2, and CPSF2 peptides showed significantly higher odds ratios with a risk of AIS in patients with the highest quartile than in those with the lowest quartile, indicating that these antibody markers are useful as risk factors for AIS.

CONCLUSIONS

Serum antibody levels of DIDO1, FOXJ2, and CPSF2 are useful in predicting the onset of atherosclerosis-related AIS caused by kidney failure, hypertension, and DM, respectively.

Serum anti-LRPAP1 is a common biomarker for digestive organ cancers and atherosclerotic diseases

Some cancers are related to atherosclerotic diseases; therefore, these two types of disease may share some antibody biomarkers in common. To investigate this, a first screening of sera was performed from patients with esophageal squamous cell carcinoma (ESCC) or acute ischemic stroke (AIS) for serological identification of antigens using recombinant cDNA expression cloning (SEREX). The amplified luminescent proximity homogeneous assay‐linked immunosorbent assay (AlphaLISA) method, which incorporates glutathione donor beads and anti‐human IgG acceptor beads, was used to evaluate serum antibody levels. SEREX screening identified low‐density lipoprotein receptor–related protein–associated protein 1 (LRPAP1) as a target antigen of serum IgG antibodies in the sera of patients with ESCC or AIS. Antigens, including recombinant glutathione S‐transferase–fused LRPAP1 protein, were prepared to examine serum antibody levels. AlphaLISA revealed significantly higher antibody levels against the LRPAP1 protein in patients with solid cancers such as ESCC and colorectal carcinoma and some atherosclerosis‐related diseases such as AIS and diabetes mellitus compared with healthy donors. Correlation analysis revealed that the elevated serum antibody levels against LRPAP1 were associated with smoking, a well‐known risk factor for both cancer and atherosclerosis. Serum LRPAP1 antibody is therefore a common marker for the early diagnosis of some cancers and atherosclerotic diseases and may reflect diseases caused by habitual smoking.