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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., (© 2024 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

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., (© 2022. The Author(s) under exclusive licence to The Japan Esophageal Society.)

Background: RalA is a member of the Ras superfamily of small GTPases. The Anti-RalA autoantibodies (s-RalA-Abs) act as tumor markers in various types of cancer and are negatively associated with the p53 autoantibodies (s-p53-Abs). This study aimed to evaluate the relationship between s-RalA-Abs and s-p53-Abs in various types of cancer., Methods: A total of 1833 cancer patients (esophageal cancer, 172; hepatocellular carcinoma, 91; lung cancer, 269; gastric cancer, 317; colon cancer, 262; breast cancer, 364; and prostate cancer, 358) and 73 healthy subjects were enrolled in the study. The levels of s-RalA-Abs and s-p53-Abs were analyzed using enzyme-linked immunosorbent assay, and the positivity rates and relations between the two autoantibodies were evaluated. The cutoff values for s-RalA abs and s-p53 abs were set as mean + 2 standard deviation and the values higher than the cutoff values were defined as positive., Results: The titers in all cancer types were significantly higher than those in the controls (P < 0.01). The positivity rates for s-RalA-Abs ranged between 11.7 and 21.5%, and those for s-p53-Abs ranged between 12 and 28.5%. A combined assay of the two antibodies revealed positivity rates of 20.9 and 44.2%. In Stage 0/I/II tumors, the positivity rates of the combination of the two antibodies ranged between 21.5 and 42.3%. The two autoantibodies were complementary to each other in the prostate and breast cancers, but independent in other carcinomas., Conclusion: The combined use of s-RalA-Abs and s-p53-Abs tended to increase the positivity rate in all cancers, including Stage 0/I/II cancers., (© 2021. Japan Society of Clinical Oncology.)

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., (© 2020 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Anti-PUF60 autoantibodies are reportedly detected in the sera of patients with dermatomyositis and Sjögren's syndrome; however, little is known regarding its existence in the sera of cancer patients. FIR, a splicing variant of the PUF60 gene, is a transcriptional repressor of c-myc. In colorectal cancer, there is an overexpression of the dominant negative form of FIR, in which exon 2 is lacking (FIRΔexon2). Previously, large-scale SEREX (serological identification of antigens by recombinant cDNA expression cloning) screenings have identified anti-FIR autoantibodies in the sera of cancer patients. In the present study, we revealed the presence and significance of anti-FIR (FIR/FIRΔexon2) Abs in the sera of patients with esophageal squamous cell carcinoma (ESCC). Our results were validated by an amplified luminescence proximity homogeneous assay using sera of patients with various cancer types. We revealed that anti-FIRΔexon2 Ab had higher sensitivity than anti-FIR Ab. Receiver operating characteristic (ROC) analysis was applied for evaluating the use of anti-FIRΔexon2 Ab as candidate markers such as anti-p53 Ab and carcinoembryonic antigen, and the highest area under the ROC curve was observed in the combination of anti-FIRΔexon2 Ab and anti-p53 Ab. In summary, our results suggest the use of anti-FIRΔexon2 Ab in combination with the anti-p53 Ab as a predictive marker for ESCC. The area under the ROC curve was further increased in the advanced stage of ESCC. The value of anti-FIRΔexon2 autoantibody as novel clinical indicator against ESCC and as a companion diagnostic tool is discussed., (© 2019 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Background: Esophageal squamous cell carcinoma (SCC) represents one of the most malignant tumors. To improve the poor prognosis, it is necessary to diagnose esophageal SCC at early stages using new tumor markers. SEREX (serological identification of antigens by recombinant cDNA expression cloning) is suitable for large-scale screening of tumor antigens and has been applied for various types of human tumors., Methods: Tumor markers of esophageal squamous cell carcinoma (SCC) were screened by SEREX method. The presence of serum anti-makorin 1 (MKRN1) antibodies (s-MKRN1-Abs) was examined by Western blotting using bacterially expressed MKRN1 protein. The expression levels of MKRN1 mRNA in tissues were examined by RT-PCR. The biological activity of MKRN1 was examined by transfection of ras-NIH3T3 mouse fibroblasts with MKRN1 cDNA. Major ubiquitinated proteins in MKRN1-transfected cells were identified by immunoprecipitation with anti-ubiquitin antibody followed by mass spectrometry., Results: MKRN1 was identified as a novel SEREX antigen of esophageal SCC. Although a total of 18 (25%) of 73 patients with esophageal SCC had s-MKRN1-Abs, none of the 43 healthy donors had a detectable level of s-MKRN1-Abs. There was no correlation between the presence of s-MKRN1-Abs and clinicopathological variables other than histological grading. Well-differentiated tumors were associated significantly with the presence of s-MKRN1-Abs in the patients. The mRNA levels of MKRN1 were frequently higher in esophageal SCC tissues than in the peripheral normal esophageal mucosa. Stable transfection of ras-NIH3T3 cells with MKRN1 cDNA induced prominent morphological changes such as enlargement of the cell body and spreading. Ubiquitination of 80- and 82-kDa proteins were clearly observed in MKRN1-transfected cells but not in the parental cells, which were identified as L-FILIP (filamin A interacting protein 1)., Conclusion: MKRN1 is a novel SEREX antigen of esophageal SCC, and s-NKRN1-Abs can be a candidate of diagnostic markers of esophageal SCC with high specificity. It is plausible that MKRN1 is involved in carcinogenesis of the well-differentiated type of tumors possibly via ubiquitination of L-FILIP.

We performed SEREX (serological identification of antigens by recombinant cDNA expression cloning) using the sera of patients with esophageal squamous cell carcinoma (SCC), and examined whether some of the SEREX antigens can affect chemosensitivity against anticancer drugs. We isolated a novel gene which was designated as AISEC (antigen identified by SEREX for esophageal carcinoma). RT-PCR analysis showed that the mRNA expression levels of AISEC were higher in esophageal SCC tissues than in their normal counterparts. By transfection into activated Ha-ras-transformed NIH3T3 (ras-NIH) mouse fibroblasts, we isolated a clone, FAISEC-3, which stably expressed AISEC. FAISEC-3 cells were more resistant to anticancer drugs, such as mitomycin C, ifosfamide, vincristine, camptothecin and etoposide, than parental ras-NIH cells. Luciferase reporter assay after a transient transfection with AISEC cDNA or the control vector revealed that the transactivity of p53 was suppressed by AISEC in a dose-dependent manner. These results suggested that esophageal SCC tissues produce AISEC in increased amounts, which can reduce the chemosensitivity against anticancer drugs possibly by suppressing the p53 transactivation ability.

Background: Serological identification of antigens by recombinant cDNA expression cloning (SEREX) is an established method for detecting new tumor-specific antigens. Antibodies to SEREX antigens may be useful for the detection of esophageal squamous cell carcinoma (SCC)., Methods: A phage cDNA library of a human esophageal SCC cell line was screened using sera of patients with esophageal SCC. The presence and levels of serum antibodies to SEREX antigens were established by Western blotting and enzyme-linked immunosorbent assay (ELISA) using purified recombinant antigen proteins, respectively., Results: The newly identified esophageal SCC antigen is encoded by a novel gene located on chromosome 1, here designated CUEC-23. Serum CUEC-23-antibodies (s-CUEC-23-Abs) were detected in 14 of 54 patients with esophageal SCC (26%) by Western blot analysis. Esophageal SCCs were positive for s-CUEC-23-Abs together with CEA, SCC-Ag or CYFRA21-1 in 44, 41 and 52% of cases, respectively. There was no detectable association between the presence of s-CUEC-23-Abs and clinicopathological variables. ELISA showed that the levels of s-CUEC-23-Abs were significantly higher in patients with esophageal SCC than in healthy volunteers (17% in the former using the mean+3 SD of s-CUEC-23-Abs in healthy controls as the cutoff)., Conclusion: A new tumor antigen, CUEC-23, was identified by SEREX screening. s-CUEC-23-Abs might be a useful serum marker to detect esophageal SCC.

In order to identify new serum markers of esophageal squamous cell carcinoma (SCC), we performed serological identification of antigens by recombinant cDNA expression cloning (SEREX). E. coli was transformed with a lambdaZAPII phage cDNA library prepared from mRNA of an esophageal cancer cell line (T.Tn), and IPTG-induced cDNA products were screened for interaction with antibodies in allogeneic sera of patients with esophageal SCC. We identified myomegalin (MMGL, phosphodiesterase 4D interacting protein/PDE4DIP) as a new SEREX antigen for esophageal SCC. Western blot analysis revealed that serum anti-myomegalin antibodies (s-MMGL-Abs) were present in 43 (47%) of 91 patients, but in only one (2.2%) of 45 healthy controls. Of the 21 patients with stage I disease, 8 (38%) were sero-positive. The positive rate of s-MMGL-Abs was greater than those of other conventional tumor markers. Reverse transcription-PCR analysis suggested that alternative splicing from myomegalin variant 1 to variant 5 may explain, in part, the development of s-MMGL-Abs. Although the presence of s-MMGL-Abs was not related to any clinicopathological features of the patients, multivariate analysis indicated that the presence of s-MMGL-Abs was significantly associated with a favorable prognosis. Consequently, s-MMGL-Abs may be a useful tumor marker to diagnose and establish a prognosis in patients with esophageal SCC.

SEREX has been applied to esophageal SCC, and the TRIM21 gene was identified as a novel SEREX antigen of esophageal SCC. The presence of s-TRIM21-Abs was confirmed by Western blotting using bacterially expressed TRIM21 gene product and was evaluated for clinicopathological significance in patients with esophageal SCC. s-TRIM21-Abs were detected in 18 (20%) of 91 patients with esophageal SCC but not in 42 healthy donors. The presence of s-TRIM21-Abs was partly associated with tumor size (P = 0.063) and poor survival (P = 0.067). To measure serum antibody levels, ELISA using purified recombinant TRIM21 protein was developed. The levels of s-TRIM21-Abs were significantly higher in patients with esophageal SCC than in healthy donors (P = 0.013). s-TRIM21-Abs may be a useful tumor marker to diagnose and predict disease progression in patients with esophageal SCC.

We have carried out SEREX (serological identification of antigens by recombinant cDNA expression cloning), and identified SLC2A1 (solute carrier family 2/facilitated glucose transporter, member 1) as an antigen recognized by serum IgG antibodies in patients with esophageal squamous cell carcinoma (SCC). The levels of serum anti-SLC2A1 antibodies (s-SLC2A1-Abs), examined by enzyme-linked immunosorbent assay using bacterially expressed glutathione-S-transferase-SLC2A1 fusion protein, were significantly higher in patients with esophageal SCC than in healthy donors. When using a cut-off level as the mean + 2x standard deviations of healthy donors, a total of 12 (21%) out of 57 SCC patients were revealed as positive for s-SLC2A1-Abs. The presence of s-SLC2A1-Abs was not associated with either clinicopathological factors or survival. Because s-SLC2A1-Abs were not associated with the positivity of other conventional serum markers, a combination assay of s-SLC2A1-Abs with these conventional serum markers may be useful for the diagnosis and monitoring of esophageal SCC.

Autoantibodies are often detected in the patients with esophageal cancer. We applied serological analysis of recombinant cDNA expression libraries (SEREX) to a case of esophageal squamous cell carcinoma in order to identify tumor antigens. A cDNA library derived from an esophageal cancer cell line was bacterially expressed and screened for interaction with antibodies in five allogeneic sera of patients with esophageal squamous cell carcinoma. To examine the specific immunoreactivity of the antigens, sera from 16 more patients with esophageal squamous cell carcinoma, 16 patients with gastric cancer, 16 patients with colon cancer, 16 patients with breast cancer and 37 healthy volunteers were screened. We identified 11 independent cDNA clones that potentially encoded esophageal cancer tumor antigens. The identified cDNA clones were SURF1, HOOK2, CENP-F, ZIC2, hCLA-iso, Ki-1/57, enigma, HCA25a, SPK and two EST clones named LOC146223 and AGENCOURT&#95;7565913. The sero-positive rates of antibodies against SURF1 (48%), LOC146223 (38%), HOOK2 (14%) and AGENCOURT&#95;7565913 (14%) were significantly higher in esophageal cancer patients than in healthy controls. At least one of these antibodies was detected in 18 (86%) of 21 sera from esophageal cancer patients. A disease-specific humoral immune response against SURF1, LOC146223, HOOK2 or AGENCOURT&#95;7565913 was observed in most patients with esophageal squamous cell carcinoma. Antibodies against these SEREX antigens may represent a pool of candidates for serum tumor markers of esophageal squamous cell carcinoma.

We applied serological analysis of recombinant cDNA expression libraries (SEREX) to cases of esophageal squamous cell carcinoma (SCC) to identify tumor antigens. One of the clones identified was TROP2, which is known as calcium signal transducer. To evaluate the clinical significance of serum anti-TROP2 antibodies (s-TROP2-Abs) in patients with esophageal SCC, the presence of s-TROP2-Abs was analyzed by Western blotting using bacterially expressed TROP2 protein. We found that 23 of 75 (31%) patients were positive for s-TROP2-Abs. Positivity in terms of s-TROP2-Abs showed a significant association with tumor size but not with other clinicopathological features. The protein expression levels of TROP2 were much higher in esophageal SCC cell lines as compared to those in normal esophageal mucosa and its immortalized cells although the mRNA expression levels were not necessarily elevated in malignant cell lines and tissues. Immunohistochemical studies showed that the expression of TROP2 protein in esophageal SCC specimens was noticeably higher than that found in mild hyperplasia of esophageal mucosae. Thus, s-TROP2-Abs seemed useful in the diagnosis of SCC and may be a candidate for serum tumor markers., ((c) 2004 Wiley-Liss, Inc.)

Heavy carbon-ion beam therapy has revealed several potential advantages over X-rays. Heavy-ion therapy has been applied for various solid tumors including esophageal squamous cell carcinoma (SCC). Although the local control rate in carbon ion radiotherapy for esophageal cancer has revealed better rates than conventional radiotherapy, severe mucosal damage was observed in adjacent normal mucosa. A suitable treatment strategy is required to reduce irradiation dose by introducing combined local therapy. Recently, we initiated clinical p53 gene therapy for esophageal SCC. We herein evaluate the cytotoxic effects of heavy carbon-ion beams combined with p53 gene transfer on human esophageal SCC. We assessed the induction of apoptosis and growth suppression with the use of recombinant adenoviral vector Ad.p53 or heavy carbon-ion beam irradiation or both. Growth suppression was significantly potentiated by combined treatment with heavy carbon-ion beams and Ad.p53 as compared to that treated with either of them alone. Western blot analysis confirmed the expression of both exogenous p53 and p21 proteins after irradiation of Ad.p53 infected cells. Enhanced apoptotic cell death was observed with a terminal deoxynucleotidyl transferase-mediated nick end-labeling assay. These data suggest that heavy carbon-ion beam irradiation combined with Ad.p53 may be a potentially effective therapeutic strategy for locally advanced esophageal SCC.

To investigate the effect of p33(ING1) on wild-type p53 gene therapy, T.Tn human esophageal carcinoma cells were stably transfected with p33(ING1) cDNA. Infection with Ad-p53 (recombinant adenovirus containing wild-type p53) into p33-transfected cells reduced cell viability, while infection with empty vector had little effect. This reduced viability was shown to be due to apoptotic cell death by the TUNEL (terminal deoxynucleotidyl transferase-mediated nick end-labeling) assay. Following infection with Ad-p53, levels of p53 were similar in p33-expressing cells and in the parental line. However, levels of p21 and Mdm2 were elevated in p33-transfected cells. Nonetheless, this enhanced expression of Mdm2 appeared to be ineffective in downregulating p53. Transient transfection with mutant Mdm2 prior to Ad-p53 infection provided a significant protection as compared with cells transfected with wild-type Mdm2. These results imply a synergistic effect between p33 and p53 in the induction of apoptosis of human esophageal carcinoma cells. A role for Mdm2 in this synergism is suggested.