Detection of gastric carcinoma-associated antigen MG7-Ag in human sera using surface plasmon resonance sensor

Clinical value of serum Mg7-Ag detection combined with magnifying endoscopy with narrow-band imaging in diagnosis of high-risk gastric low-grade intraepithelial neoplasia

BACKGROUND

Human gastric cancer associated antigen (Mg7-Ag) can be highly expressed in gastric cancer cell lines, and is closely related to gastric cancer progression. Magnifying endoscopy with narrow-band imaging (ME-NBI) has high sensitivity and specificity in the diagnosis of early gastric cancer, especially for differentiated gastric cancer. This study assessed the clinical diagnostic value of serum Mg7-Ag detection combined with ME-NBI for high-risk low grade intraepithelial neoplasia (LGIN).

AIM

To evaluate the clinical value of serum Mg7-Ag detection combined with ME-NBI in judging whether there is pathological upgrading of gastric LGIN after endoscopic dissection (ESD).

METHODS

Patients who were diagnosed with LGIN at our hospital from January 2019 to December 2022 and underwent diagnostic ESD within 1 mo were selected and divided into a high-risk group (pathologically upgraded), a low-risk group (pathologically not upgraded), and an inflammation group (pathologically downgraded) according to the differences in pathological results after ESD and preoperative endoscopic biopsy. Serum Mg7-Ag levels were detected in all cases within 1 week before ESD, and gastroscopic ME-NBI screening was performed. The levels of serum Mg7-Ag, the number of Mg7-Ag (+) and Mg7-Ag (-) patients, and the number of ME-NBI (+) and ME-NBI (-) patients in the three groups were recorded. The sensitivity, specificity, accuracy, and positive likelihood ratio of serum Mg7-Ag and ME-NBI, alone and in combination, for predicting pathological upgrading after ESD of LGIN lesions were calculated and analyzed.

RESULTS

A total of 125 patients with gastric LGIN who underwent diagnostic ESD were included in this study, including 37 in the high-risk group, 76 in the low-risk group, and 12 in the inflammation group. Serum Mg7-Ag levels were significantly different among the three groups (P < 0.05), and Mg7-Ag levels in the high-risk group were significantly higher than those in the low-risk group and the inflammation group (P < 0.05). The positive rate of ME-NBI in the inflammation group was significantly lower than those in the other two groups (P < 0.05), and the rate in the high-risk group was higher than that in the low-risk group (P < 0.05). There was no significant difference in the sensitivity, specificity, accuracy, and positive likelihood ratio of Mg7-Ag and ME-NB alone in predicting the pathological upgrading of LGIN (P > 0.05). The sensitivity of combined Mg7-Ag detection and ME-NBI in predicting high-risk LGIN was slightly lower than that of either of them alone; the specificity was 90.5%, the accuracy was 84.0%, and the positive likelihood ratio was 2.417, all of which were significantly higher than those of single tests (P < 0.05). When Mg7-Ag + ME-NBI results were negative, the accuracy and positive likelihood for cases in the inflammation group were significantly higher than those of single tests (P < 0.05).

CONCLUSION

Combined serum Mg7-Ag detection and ME-NBI screening has important clinical value in judging whether gastric LGIN lesions will undergo pathological upgrading.

PGC-MG7 combination could be used as a follow-up panel for monitoring dynamical progression of gastric precancerous diseases

Objective

The aim of this study was to investigate the value of the combined expression of the gastric mucosal differentiation protein pepsinogen C (PGC) and gastric cancer (GC)-associated antigen MG7 for the diagnosis of GC and prediction of the development from precancerous conditions to GC.

Methods

The gastric mucosal biopsies of 285 subjects enrolled from a region with a high incidence of GC were obtained and histopathologically examined. Subjects testing negative for GC (n=208) were followed up from 1998 to 2015. The levels of PGC and MG7 in the biopsies were determined by immunohistochemistry.

Results

PGC was positive in 91.4% of the non-atrophic gastritis, 26.5% of the atrophic gastritis, and 0% of the GC. MG7 was positive in 15.0% of the non-atrophic gastritis, 82.4% of the atrophic gastritis, and 94.8% of the GC. The non-atrophic gastritis group was predominantly “PGC+MG7−”. The atrophic gastritis and GC groups were predominantly “PGC−MG7+”. The rate of GC in subjects with “PGC−MG7+” staining was 113.4-fold higher [95% confidence interval (95% CI): 15.3−869.4, P<0.001] than that in subjects with other staining patterns. The sensitivity and specificity of the “PGC−MG7+” pattern were 92.2% and 78.8% for the detection of GC and 77.2% and 97.9% for GC and precancerous disease, respectively. In the follow-up cohort of non-GC subjects, the risk of developing GC was higher in those with the “PGC−MG7+” staining pattern.

Conclusions

Our data suggest that the “PGC−MG7+” pattern can be employed as a useful follow-up panel for detecting individuals with a high risk of GC, and the dynamic assessment of the follow-up panel needs multi-centre large-scale validation in the future.

Detection of serum Mg7-Ag, CEA and pepsinogens combined with magnifying narrow-band imaging endoscopy for screening early gastric carcinoma in high risk patients

AIM

To assess the clinical value of serum Mg7-Ag, carcinoembryonic antigen (CEA), pepsinogen (PG) I, PGⅡ and PGI/PGⅡ ratio (PGR) combined with magnifying narrow-band imaging endoscopy (ME-NBI) for screening early gastric cancer (GC) in high-risk patients.

METHODS

A total of 802 patients at a high risk for GC were selected for the study. ELISA was used to detect serum Mg7-Ag, PGI, PGII, and CEA levels, and the PGR was calculated. According to the results, the patients were categorized as Mg7-Ag (+) and Mg7-Ag (-), PGI (+) and PGI (-), PGR (+) and PGR (-), and CEA (+) and CEA (-). Gastroscopy was performed for all enrolled patients, and gastric lesions were examined by ME-NBI and pathological examination was performed. According to the pathological results, the patients were divided into an inflammatory group, a precancerous disease group, an atypical hyperplasia group, an early GC group and an advanced GC group. Serum Mg7-Ag, PGI and PGR values and the number of patients with positive results were compared among different groups, and the sensitivity, specificity and accuracy of these indexes, alone or in combination, for early diagnosis of GC were calculated.

RESULTS

Serum level of PGI in the non-inflammatory group was significantly lower than that in the simple inflammatory group (P < 0.05). Serum levels of Mg7-Ag and CEA in the GC group were significantly higher than those in the non-GC group (P < 0.05). However, serum level of Mg7-Ag in the early GC group was not significantly different from that in the advanced GC group, while serum CEA level of the advanced GC group was significantly higher than that in the early GC group (P < 0.05). The sensitivity of Mg7-Ag combined with ME-NBI for diagnosing early GC was significantly higher than that of PGR and PGI (P < 0.05), but there was no significant difference in specificity between each group (P > 0.05). The accuracy of CEA in the diagnosis of GC was the lowest, and the accuracy of Mg7-Ag and ME-NBI detection was significantly higher than that of PGR and PGI. The sensitivity and accuracy of combined detection of PGI + PGR, PGI + PGR + Mg7-Ag, and PGI + PGR + Mg7-Ag + ME-NBI increased gradually, while there was no significant difference in specificity (P > 0.05). Positive result of PGI + PGR + Mg7-Ag + ME-NBI combined with CEA (-) had significantly higher sensitivity and accuracy than PGI + PGR + Mg7-Ag + ME-NBI (P < 0.05), although there was no significant difference in specificity (P > 0.05).

CONCLUSION

Combined detection of serum Mg7-Ag, PG and CEA plus ME-NBI examination is of great clinical significance for screening early GC in highly suspicious people.

A global burden of gastric cancer: the major impact of China

Gastric cancer (GC) is a highly aggressive cancer and a major cause of cancer-related deaths worldwide. Approximately half of the world's GC cases and deaths occur in china. GC presents challenges in early diagnosis and effective therapy due to a lack of understanding of the underlying molecular biology. The primary goals of this review are to outline current GC research in china and describe future trends in this field. Areas covered: This review mainly focuses on a series of GC-related advances China has achieved. Considerable progress has been made in understanding the role of H. pylori in GC by a series of population-based studies in well-established high-risk areas; A few germline and somatic alterations have been identified by 'omics' studies; Studies on the mechanisms of malignant phenotypes have helped us to form an in-depth understanding of GC and advance drug discovery. Moreover, identification of potential biomarkers and targeted therapies have facilitated the diagnosis and treatment of GC. However, many challenges remain. Expert commentary: To combat GC, sufficient funding is important. More attention should be paid on early diagnosis and the discovery of novel efficient biomarkers and the development of biomarker-based or targeted therapeutics in GC.

Emerging microfluidic devices for cancer cells/biomarkers manipulation and detection

Circulating tumour cells (CTCs) are active participants in the metastasis process and account for ∼90% of all cancer deaths. As CTCs are admixed with a very large amount of erythrocytes, leukocytes, and platelets in blood, CTCs are very rare, making their isolation, capture, and detection a major technological challenge. Microfluidic technologies have opened-up new opportunities for the screening of blood samples and the detection of CTCs or other important cancer biomarker-proteins. In this study, the authors have reviewed the most recent developments in microfluidic devices for cells/biomarkers manipulation and detection, focusing their attention on immunomagnetic-affinity-based devices, dielectrophoresis-based devices, surface-plasmon-resonance microfluidic sensors, and quantum-dots-based sensors.

Elevated amino acids in gastric juice as potential biomarkers for gastric cancer

Early diagnosis plays a vital role in the improvement of the curative rate of gastric cancer. However, the poor specificity and sensitivity of traditional gastric cancer biomarkers, such as carcino-embryonic antigen and carbohydrate antigen 199, make it difficult to screen early gastric cancer. Gastric juice amino acid profile may be an alternative tumor marker, since abnormal elevation of amino acids in gastric juice has been reported in precancerous patients. Normal concentration of amino acids is extremely low in gastric juice, and special techniques are required to detect amino acids in gastric juice. The change of amino acids in gastric juice is more significant than in blood and tumor tissue. The amino acid profile in gastric juice may work as efficient biomarkers for gastric cancer with the development of amino acid detection technique.

Conjugation of toll-like receptor-7 agonist to gastric cancer antigen MG7-Ag exerts antitumor effects

AIM: To investigate the effects of our tumor vaccines on reversing immune tolerance and generating therapeutic response.

METHODS: Vaccines were synthesized by solid phase using an Fmoc strategy, where a small molecule toll-like receptor-7 agonist (T7) was conjugated to a monoclonal gastric cancer 7 antigen mono-epitope (T7-MG1) or tri-epitope (T7-MG3). Cytokines were measured in both mouse bone marrow dendritic cells and mouse spleen lymphocytes after exposed to the vaccines. BALB/c mice were intraperitoneally immunized with the vaccines every 2 wk for a total of three times, and then subcutaneously challenged with Ehrlich ascites carcinoma (EAC) cells. Three weeks later, the mice were killed, and the tumors were surgically removed and weighed. Serum samples were collected from the mice, and antibody titers were determined by ELISA using an alkaline phosphate-conjugated detection antibody for total IgG. Antibody-dependent cell-mediated cytotoxicity was detected by the lactate dehydrogenase method using natural killer cells as effectors and antibody-labeled EAC cells as targets. Cytotoxic T lymphocyte activities were also detected by the lactate dehydrogenase method using lymphocytes as effectors and EAC cells as targets.

RESULTS: Vaccines were successfully synthesized and validated by analytical high performance liquid chromatography and electrospray mass spectrometry, including T7, T7-MG1, and T7-MG3. Rapid inductions of tumor necrosis factor-α and interleukin-12 in bone marrow dendritic cells and interferon γ and interleukin-12 in lymphocytes occurred in vitro after T7, T7-MG1, and T7-MG3 treatment. Immunization with T7-MG3 reduced the EAC tumor burden in BALB/c mice to 62.64% ± 5.55% compared with PBS control (P < 0.01). Six or nine weeks after the first immunization, the monoclonal gastric cancer 7 antigen antibody increased significantly in the T7-MG3 group compared with the PBS control (P < 0.01). As for antibody-dependent cell-mediated cytotoxicity, antisera obtained by immunization with T7-MG3 were able to markedly enhance cell lysis compared to PBS control (31.58% ± 2.94% vs 18.02% ± 2.26%; P < 0.01). As for cytotoxic T lymphocytes, T7-MG3 exhibited obviously greater cytotoxicity compared with PBS control (40.92% ± 4.38% vs 16.29% ± 1.90%; P < 0.01).

CONCLUSION: A successful method is confirmed for the design of gastric cancer vaccines by chemical conjugation of T7 and multi-repeat-epitope of monoclonal gastric cancer 7 antigen.

The diagnostic value of monoclonal gastric cancer 7 antigen: a systematic review with meta-analysis

The aim of this study is to explore the clinical characteristic and the diagnostic role of MG7-Ag in detecting gastric cancer (GC) through a systematic review and meta-analysis. Relevant manuscripts aiming at the application of serum MG7-Ag level in GC diagnosis were searched in PubMed, Embase, Chinese National Knowledge Infrastructure, VIP, and Wan Fang Data independently,which were published between January 1, 1980 and February 28, 2013. The pooled sensitivity, specificity,positive diagnostic likelihood ratio (DLR+), negative diagnostic likelihood ratio (DLR-), diagnostic odds ratio,and the area under the summary receiver operating characteristic(AUC) were used to evaluate the value of serum MG7-Ag in diagnosis of GC by using the Meta-DiSc and STATA 11.0 statistical software. 410 manuscripts were retrieved, and 7 manuscripts of high quality including 652 patients were of high quality in this meta-analysis. Overall,the pooled sensitivity, specificity, DLR+, DLR-, and AUC were 0.73 (95 % CI 0.63-0.82), 0.91 (95 % CI 0.84-0.94), 8.59 (95 % CI 5.62-13.11), 0.29 (95 % CI 0.21-0.42), and 0.92 (95 % CI 0.89-0.94), respectively. MG7-Ag is a potential biomarker for the diagnosis of GC.However, more studies are needed to confirm the standard criteria.

Evaluation of 68Ga-labeled MG7 antibody: a targeted probe for PET/CT imaging of gastric cancer

MG7-Ag, a specific gastric cancer-associated antigen, can be used to non-invasively monitor gastric cancer by molecular imaging with positron emission tomography/computed tomography (PET/CT). In this study, we prepared and evaluated a ⁶⁸Ga-labeled MG7 antibody as a molecular probe for nanoPET/CT imaging of gastric cancer in a BGC-823 tumor xenografted mouse model. Macrocyclic chelator 1,4,7-triazacyclononane-N,N0,N00-triacetic acid (NOTA)-conjugated MG7 antibody was synthesized and radiolabeled with ⁶⁸Ga (t_1/2 = 67.71 min). Then, ⁶⁸Ga-NOTA-MG7 was tested using in vitro cytological studies, in vivo nanoPET/CT and Cerenkov imaging studies as well as ex vivo biodistribution and histology studies. The in vitro experiments demonstrated that ⁶⁸Ga-NOTA-MG7 has an excellent radiolabeling efficiency of approximately 99% without purification, and it is stable in serum after 120 min of incubation. Cell uptake and retention studies confirmed that ⁶⁸Ga-NOTA-MG7 has good binding affinity and tumor cell retention. For the nanoPET imaging study, the predominant uptake of ⁶⁸Ga-NOTA-MG7 was visualized in tumor, liver and kidneys. The tumor uptake reached at its peak (2.53 ± 0.28%ID/g) at 60 min pi. Cherenkov imaging also confirmed the specificity of tumor uptake. Moreover, the biodistribution results were consistent with the quantification data of nanoPET/CT imaging. Histologic analysis also demonstrated specific staining of BGC-823 tumor cell lines.

Serum protein and genetic tumor markers of gastric carcinoma

The high incidence of gastric cancer and consequent mortality pose severe threats to human health. Early screening, diagnosis and treatment are the key to improve the prognosis of the patients with gastric cancer. Gastroscopy with biopsy is an efficient method for the diagnosis of early gastric cancer, but the associated discomfort and high cost make it difficult to be a routine method for screening gastric cancer. Serum tumor marker assay is a simple and practical method for detection of gastric cancer, but it is limited by poor sensitivity and specificity. Therefore, people have been looking for novel serum markers of gastric cancer in recent years. Here we review the novel serum tumor markers of gastric cancer and their diagnostic significance, focusing on the discoveries from serum proteomics analyses and epigenetics researches.