Pre-operative serum levels of sialyl Tn antigen predict liver metastasis and poor prognosis in patients with gastric cancer

alpha2,3 sialic acid processing enzymes expression in gastric cancer tissues reveals that ST3Gal3 but not Neu3 are associated with Lauren's classification, angiolymphatic invasion and histological grade

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. Despite progress in the last decades, there are still no reliable biomarkers for the diagnosis of and prognosis for GC. Aberrant sialylation is a widespread critical event in the development of GC. Neuraminidases (Neu) and sialyltransferases (STs) regulate the ablation and addition of sialic acid during glycoconjugates biosynthesis, and they are a considerable source of biomarkers in various cancers. This study retrospectively characterized Neu3 and ST3Gal3 expression by immunohistochemistry in 71 paraffin-embedded GC tissue specimens and analyzed the relationship between their expression and the clinicopathological parameters. Neu3 expression was markedly increased in GC tissues compared with non-tumoral tissues (p<0.0001). Intratumoral ST3Gal3 staining was significantly associated with intestinal subtype (p=0.0042) and was negatively associated with angiolymphatic invasion (p=0.0002) and higher histological grade G3 (p=0.0066). Multivariate analysis revealed that ST3Gal3 positivity is able to predict Lauren's classification. No associations were found between Neu3 staining and clinical parameters. The in silico analysis of mRNA expression in GC validation cohorts corroborates the significant ST3Gal3 association with higher histological grade observed in our study. These findings suggest that ST3Gal3 expression may be an indicator for aggressiveness of primary GC.

Truncated O-Glycan-Bearing MUC16 Enhances Pancreatic Cancer Cells Aggressiveness via α4β1 Integrin Complexes and FAK Signaling

Elevated levels of Mucin-16 (MUC16) in conjunction with a high expression of truncated O-glycans is implicated in playing crucial roles in the malignancy of pancreatic ductal adenocarcinoma (PDAC). However, the mechanisms by which such aberrant glycoforms present on MUC16 itself promote an increased disease burden in PDAC are yet to be elucidated. This study demonstrates that the CRISPR/Cas9-mediated genetic deletion of MUC16 in PDAC cells decreases tumor cell migration. We found that MUC16 enhances tumor malignancy by activating the integrin-linked kinase and focal adhesion kinase (ILK/FAK)-signaling axis. These findings are especially noteworthy in truncated O-glycan (Tn and STn antigen)-expressing PDAC cells. Activation of these oncogenic-signaling pathways resulted in part from interactions between MUC16 and integrin complexes (α4β1), which showed a stronger association with aberrant glycoforms of MUC16. Using a monoclonal antibody to functionally hinder MUC16 significantly reduced the migratory cascades in our model. Together, these findings suggest that truncated O-glycan containing MUC16 exacerbates malignancy in PDAC by activating FAK signaling through specific interactions with α4 and β1 integrin complexes on cancer cell membranes. Targeting these aberrant glycoforms of MUC16 can aid in the development of a novel platform to study and treat metastatic pancreatic cancer.

Practical guidance for the evaluation of disease progression and the decision to change treatment in patients with advanced gastric cancer receiving chemotherapy

After failure of first-line chemotherapy with fluoropyrimidines and platinum compounds for advanced gastric cancer, second-line chemotherapy with ramucirumab plus paclitaxel, which elicits a durable response, and third-line or later chemotherapy with nivolumab have been shown to lead to a more favorable prognosis in advanced gastric cancer patients. As new and more effective drugs are now available, sequential chemotherapy would contribute to prolonged survival. From this point of view, the patient's disease course should be frequently monitored in order to adapt treatment regimens. This review summarizes the points to note in regard to radiological assessment, and discusses the integration of prognostic factors, tumor markers, and clinical symptoms that need to be taken into account to change treatment at an appropriate timing.

The sialoglycan-Siglec glyco-immune checkpoint - a target for improving innate and adaptive anti-cancer immunity

Introduction: During cancer progression, tumor cells develop several mechanisms to prevent killing and to shape the immune system into a tumor-promoting environment. One of such regulatory mechanism is the overexpression of sialic acid (Sia) on carbohydrates of proteins and lipids on tumor cells. Sia-containing glycans or sialoglycans were shown to inhibit immune effector functions of NK cells and T cells by engaging inhibitory Siglec receptors on the surface of these cells. They can also modulate the differentiation of myeloid cells into tumor-promoting M2 macrophages. Areas covered: We review the role of sialoglycans in cancer and introduce the Siglecs, their expression on different immune cells and their interaction with cancer-associated sialoglycans. The targeting of this sialoglycan-Siglec glyco-immune checkpoint is discussed along with potential therapeutic approaches. Pubmed was searched for publications on Siglecs, sialic acid, and cancer. Expert opinion: The targeting of sialoglycan-Siglec interactions has become a major focus in cancer research. New approaches have been developed that directly target sialic acids in tumor lesions. Targeted sialidases that cleave sialic acid specifically in the tumor, have already shown efficacy; efforts targeting the sialoglycan-Siglec pathway for improvement of CAR T cell therapy are ongoing. The sialoglycan-Siglec immune checkpoint is a promising new target for cancer immunotherapy.

Different isolation approaches lead to diverse glycosylated extracellular vesicle populations

Extracellular vesicles (EVs) are a heterogeneous group of small secreted particles involved in intercellular communication and mediating a broad spectrum of biological functions. EVs cargo is composed of a large repertoire of molecules, including glycoconjugates. Herein, we report the first study on the impact of the isolation strategy on the EV populations’ glycosylation profile. The use of different state-of-the-art protocols, namely differential ultracentrifugation (UC), total exosome isolation (TEI), OptiPrep^TM density gradient (ODG) and size exclusion chromatography (SEC) resulted in EV populations displaying different sets of glycoconjugates. The EV populations obtained by UC, ODG and SEC methods displayed similar protein and glycan profiles, whereas TEI methodology isolated the most distinct EV population. In addition, ODG and SEC isolation protocols provided an enhanced EV glycoproteins detection. Remarkably, proteins displaying the tumour-associated glycan sialyl-Tn (STn) were identified as packaged cargo into EVs independently of the isolation methodology. STn carrying EV samples isolated by UC, ODG and SEC presented a considerable set of cancer-related proteins that were not detected in EVs isolated by TEI. Our work demonstrates the impact of using different isolation methodologies in the populations of EVs that are obtained, with consequences in the glycosylation profile of the isolated population. Furthermore, our results highlight the importance of selecting adequate EV isolation protocols and cell culture conditions to determine the structural and functional complexity of the EV glycoconjugates.

O-glycans truncation modulates gastric cancer cell signaling and transcription leading to a more aggressive phenotype

BACKGROUND

Changes in glycosylation are known to play critical roles during gastric carcinogenesis. Expression of truncated O-glycans, such as the Sialyl-Tn (STn) antigen, is a common feature shared by many cancers and is associated with cancer aggressiveness and poor-prognosis.

METHODS

Glycoengineered cell lines were used to evaluate the impact of truncated O-glycans in cancer cell biology using in vitro functional assays, transcriptomic analysis and in vivo models. Tumor patients 'samples and datasets were used for clinical translational significance evaluation.

FINDINGS

In the present study, we demonstrated that gastric cancer cells expressing truncated O-glycans display major phenotypic alterations associated with higher cell motility and cell invasion. Noteworthy, the glycoengineered cancer cells overexpressing STn resulted in tumor xenografts with less cohesive features which had a critical impact on mice survival. Furthermore, truncation of O-glycans induced activation of EGFR and ErbB2 receptors and a transcriptomic signature switch of gastric cancer cells. The disclosed top activated genes were further validated in gastric tumors, revealing that SRPX2 and RUNX1 are concomitantly overexpressed in gastric carcinomas and its expression is associated with patients' poor-survival, highlighting their prognosis potential in clinical practice.

INTERPRETATION

This study discloses novel molecular links between O-glycans truncation frequently observed in cancer and key cellular regulators with major impact in tumor progression and patients' clinical outcome.

Clinical Assessment and Prognostic Evaluation of Tumor Markers in Patients with Gastric Cancer

Aim

To investigate the relationship between the serum levels of CEA, CA19-9, CA24-2, CA72-4, and AFP in patients with gastric cancer (GC) and their clinicopathological characteristics; to analyze the efficacy of these tumor markers in evaluating the prognosis of GC.

Methods

Overall, 389 patients with GC either located in the gastric cardia (132), the pyloric antrum (112) or the body of the stomach (145) were included in the study. Serum levels of CEA, CA19-9, CA72-4, and AFP were detected with the ECLIA method, while CA24-2 was measured with ELISA.

Results

First, the serum level of CEA in GC patients with a cardia-located cancer was significantly higher than in patients with pyloric antrum-located cancer (p=0.050). CA72-4 level in patients with GC located in the gastric body was significantly higher than in patients with cardia and pyloric antrum-located cancers (p=0.042 and p=0.039, respectively). Secondly, serum CA19-9 and CA24-2 levels in females with cardia-located GC were significantly higher than those in males with the same type of tumor (p=0.037 and p=0.033, respectively). Additionally, for females with gastric body-located GC the levels of CEA and CA72-4 were significantly higher than those in male patients with the same type of tumor (p=0.047 and p=0.048, respectively). Conversely, in female GC patients with pyloric antrum-located cancer the serum levels of CA19-9 and CA24-2 were significantly lower than those in male patients with the same type of cancer (p=0.013 and p=0.007, respectively). Moreover, CEA, CA19-9, CA24-2, and CA72-4 levels were strongly related to TNM grade and histological anatomy stage, whereas CEA and CA72-4 levels were strongly related to lymph node stage (p=0.000 and p=0.042, respectively). Patients with vascular embolism had higher serum levels of CEA, CA19-9, CA24-2, and CA72-4 compared with patients without vascular embolism (p=0.005, p=0.031, p=0.007, and p=0.014, respectively). In patients with distant metastases and ascites the levels of CEA, CA19-9, and CA24-2 were higher than in patients without these conditions (p=0.003, p=0.001, p=0.001, p=0.016, p= 0.011, and p=0.030, respectively). Serum CEA, CA19-9, and CA24-2 levels showed correlations with tumor invasive depth and growth types (p=0.001, p=0.040, and p=0.035, respectively). Patients with lump and catheter tumor growth types had significantly higher AFP levels than patients with invasion and anabrosis growth types (p=0.034 and p=0.005, respectively). Tumor size was correlated with the preoperative serum levels of CEA, AFP, and CA72-4 (p=0.007, p=0.020, and p=0.008, respectively). Additionally multiple linear regression analysis showed that preoperative levels of CEA and CA72-4 were correlated to TNM stages, CA19-9 and CA24-2 levels were correlated to both gender and distant metastasis, and AFP was correlated only to ascites. During follow-up there were 115 deaths. Median survival time for GC patients with negative preoperative CEA was 18.07 months, and was 10.97 months for patients with preoperative CEA positive levels (p=0.0005). Similarly, the median survival time for GC patients with negative preoperative CA72-4 was 33.60, and was 16.03 months for patients with preoperative CA72-4 positive levels (p=0.0041).

Conclusions

The preoperative levels of CEA, CA19-9, CA24-2, CA72-4, and AFP were closely related to TNM grade, gender, distant metastasis and ascites. These makers seem to play important roles in predicting recurrence and metastasis, and in evaluating prognosis.

A glycoproteomic approach to identify novel glycomarkers for cancer stem cells

Most cancers consist of heterogeneous populations of cells with substantial differences in tumorigenicity. Cells that possess self-renewal and tumor-initiating properties are often called cancer stem cells (CSCs). Since CSCs underlie tumor recurrence and metastasis and are resistant to current anti-cancer therapies, novel therapeutic strategies to efficiently target this subset of cells are needed. Aberrant glycosylation is one of the hallmarks of cancer. Many cancer-associated glycans have been reported to be involved in tumor progression and metastasis, and are used as tumor markers. Over the past several years, we have identified characteristic glycans on CSCs by utilizing recent advances in glycoproteomic technologies. In this review, we would like to summarize a series of our recent studies and discuss possible applications of glycomarkers for CSCs.

Probing the O-glycoproteome of gastric cancer cell lines for biomarker discovery

Circulating O-glycoproteins shed from cancer cells represent important serum biomarkers for diagnostic and prognostic purposes. We have recently shown that selective detection of cancer-associated aberrant glycoforms of circulating O-glycoprotein biomarkers can increase specificity of cancer biomarker assays. However, the current knowledge of secreted and circulating O-glycoproteins is limited. Here, we used the COSMC KO "SimpleCell" (SC) strategy to characterize the O-glycoproteome of two gastric cancer SimpleCell lines (AGS, MKN45) as well as a gastric cell line (KATO III) which naturally expresses at least partially truncated O-glycans. Overall, we identified 499 O-glycoproteins and 1236 O-glycosites in gastric cancer SimpleCells, and a total 47 O-glycoproteins and 73 O-glycosites in the KATO III cell line. We next modified the glycoproteomic strategy to apply it to pools of sera from gastric cancer and healthy individuals to identify circulating O-glycoproteins with the STn glycoform. We identified 37 O-glycoproteins in the pool of cancer sera, and only nine of these were also found in sera from healthy individuals. Two identified candidate O-glycoprotein biomarkers (CD44 and GalNAc-T5) circulating with the STn glycoform were further validated as being expressed in gastric cancer tissue. A proximity ligation assay was used to show that CD44 was expressed with the STn glycoform in gastric cancer tissues. The study provides a discovery strategy for aberrantly glycosylated O-glycoproteins and a set of O-glycoprotein candidates with biomarker potential in gastric cancer.

Clinical significance of serum tumor markers for gastric cancer: a systematic review of literature by the Task Force of the Japanese Gastric Cancer Association

The aim of this review was to evaluate the clinical significance of serum tumor markers, particularly CEA, CA19-9, and CA72-4, in patients with gastric cancer. A systematic literature search was performed using PubMed/MEDLINE with the keywords "gastric cancer" and "tumor marker," to select 4,925 relevant reports published before the end of November 2012. A total of 187 publications contained data for CEA and CA19-9, and 19 publications contained data related to all three tumor markers. The positive rates were 21.1 % for CEA, 27.8 % for CA19-9, and 30.0 % for CA72-4. These three markers were significantly associated with tumor stage and patient survival. Serum markers are not useful for early cancer, but they are useful for detecting recurrence and distant metastasis, predicting patient survival, and monitoring after surgery. Tumor marker monitoring may be useful for patients after surgery because the positive conversion of tumor markers usually occurs 2-3 months before imaging abnormalities. Among other tumor markers, alpha-fetoprotein (AFP) is useful for detecting and predicting liver metastases. Moreover, CA125 and sialyl Tn antigens (STN) are useful for detecting peritoneal metastases. Although no prospective trial has yet been completed to evaluate the clinical significance of these serum markers, this literature survey suggests that combinations of CEA, CA19-9, and CA72-4 are the most effective ways for staging before surgery or chemotherapy. In particular, monitoring tumor markers that were elevated before surgery or chemotherapy could be useful for detection of recurrence or evaluation of the response.

Survival Advantage in Patients with Metastatic Breast Cancer Receiving Endocrine Therapy plus Sialyl Tn-KLH Vaccine: Post Hoc Analysis of a Large Randomized Trial

Background: A multicenter, double blinded, randomized phase III trial of the therapeutic cancer vaccine sialy1-Tn (STn) conjugated to keyhole-limpet Hemocyanin (KLH) was completed in an international cohort of 1,028 women with metastatic breast cancer who had nonprogressive disease or no evidence of disease after first-line chemotherapy (ClinicalTrials.gov, (NCT00003638). STn-KLH was safe and relatively well tolerated but did not affect time to progression (TTP) or overall survival (OS) duration. The purpose of this post hoc analysis was to explore whether patients who received concurrent endocrine therapy and STn-KLH had a TTP or OS benefit.

Methods: A retrospective, blinded review of the data from the phase III trial of STn-KLH was performed to ensure that strata assignments were appropriate. We then studied the effect of concomitant endocrine therapy and STn-KLH or KLH on TTP and OS in the cohort described above. We also assessed the TTP and OS by antibody responses in patients who received endocrine therapy.

Results: The women treated with concomitant endocrine therapy, a pre-stratified subset comprising approximately one-third of the original study population, and STn-KLH had longer TTP and OS than the control group of women who received KLH alone. Moreover, of the women who received endocrine therapy, those who had a median or greater antibody response (titer >1:320 toward ovine sub maxillary mucin) to the STn-KLH vaccine had significantly longer median OS than those who had a below-median antibody response.

Conclusion: Adding STn-KLH to endocrine therapy may improve clinical outcomes with few adverse effects for women with metastatic breast cancer.

Sialyl-tn in cancer: (how) did we miss the target?

Sialyl-Tn antigen (STn) is a short O-glycan containing a sialic acid residue α2,6-linked to GalNAcα-O-Ser/Thr. The biosynthesis of STn is mediated by a specific sialyltransferase termed ST6GalNAc I, which competes with O-glycans elongating glycosyltransferases and prevents cancer cells from exhibiting longer O-glycans. While weakly expressed by fetal and normal adult tissues, STn is expressed by more than 80% of human carcinomas and in all cases, STn detection is associated with adverse outcome and decreased overall survival for the patients. Because of its pan-carcinoma expression associated with an adverse outcome, an anti-cancer vaccine, named Theratope, has been designed towards the STn epitope. In spite of the great enthusiasm around this immunotherapy, Theratope failed on Phase III clinical trial. However, in lieu of missing this target, one should consider to revise the Theratope design and the actual facts. In this review, we highlight the many lessons that can be learned from this failure from the immunological standpoint, as well as from the drug design and formulation and patient selection. Moreover, an irrefutable knowledge is arising from novel immunotherapies targeting other carbohydrate antigens and STn carrier proteins, such as MUC1, that will warrantee the future development of more successful anti-STn immunotherapy strategies.

In-site interaction evaluation of Tn density by inhibition/competition assays

The tumor-associated structure N-acetyl-galactosamine-O-Ser/Thr (Tn antigen), which is overexpressed in various tumor cell types, notably of the breast, ovary and colon, is an interesting determinant that is useful for cancer diagnosis and follow-up. The aim of this research was to study different assay strategies in order to determine the most sensitive system for further application in epitope characterization and binding assessment. The tetrameric isolectin obtained from Vicia villosa seeds (VVLB(4)) shows high affinity for the tumor-associated structure. A monoclonal antibody against VVLB(4), MabVV(34), was generated, and the interaction between MabVV(34) and VVLB(4) was studied by means of binding and inhibition assays. Several synthetic peptides (10 amino acid sequences) designed from the amino acid sequence of VVLB(4) and obtained from trypsin digestion were tested to determine which amino acids were involved in the interaction between MabVV(34) and VVLB(4). The further unraveling of this epitope was investigated by inhibition using designed synthetic peptides as well as mixtures mimicking variable density effect. Under the experimental circumstances, MabVV(34) was able to inhibit the binding of VVLB(4) to Tn. Two of the four peptide sequences assayed showed better inhibition properties. Finally, mixtures containing these selected sequences allowed the evaluation of binding and inhibition as a function of Tn density. We conclude that the present study facilitates the further development of a specific Tn marker and may contribute to the development of Tn-like radiolabelled peptides or Tn-specific radiolabelled fragments providing a highly selective tool for cancer diagnosis and treatment. This strategy may contribute to characterize the new generation of radiopharmaceuticals for diagnosis and therapy based on biomolecules like antibodies, fragments or peptides, whose application is directly guided by their specific molecular recognition.

Strategies for treating liver metastasis from gastric cancer

The prognosis of patients with liver metastasis from gastric cancer is dismal. This article reviews the characteristics of gastric cancer metastasizing to the liver, and multimodality of treatments. Differentiated adenocarcinoma, poorly differentiated adenocarcinoma with a medullary growth pattern, and special types, including endocrine carcinoma and hepatoid carcinoma, are likely to metastasize to the liver. The overexpression of growth factors or adhesion molecules is clinically significant for liver metastasis. Surgery for liver metastases arising from gastric adenocarcinoma is reasonable if a complete resection seems feasible after careful preoperative staging. A hepatic resection should always be considered as an option for gastric cancer patients with hepatic metastases. Newer generation cytotoxic agents such as S-1, irinotecan, and taxanes show promising activity for patients with metastases. Adjuvant chemotherapy or molecular targeted therapy will provide significant benefits to patients in the future.

Role of serum tumor markers in monitoring for recurrence of gastric cancer following radical gastrectomy

It has been suggested that the serum tumor markers AFP, CEA, and CA19-9 may serve as prognostic factors or indicators for recurrence after radical gastrectomy for gastric cancer. We compared the value of these markers in a group with (n=52) and a group without recurrent gastric cancer (n=52) according to the site of recurrence. Serum levels of tumor markers were measured at the time of preoperative diagnosis and at follow-up. At least one tumor marker was positive preoperatively in 20 with recurrence vs. 7 controls (p=0.007). The peritoneum was the most common recurrent site. The positive predictive value of AFP was high at the time of diagnosis and CA19-9 positivity was high at the time of recurrence. Positive CEA suggested recurrence to the liver. In summary, an elevated tumor marker at diagnosis or during follow up may identify patients at higher risk for a recurrence. CA19-9 may be especially useful as a marker for peritoneal recurrence of the gastric cancer, and CEA for recurrence to liver.

CDw75 is a significant histopathological marker for gastric carcinoma

AIM: To study the expression of CDw75 in patients with gastric carcinoma and to correlate CDw75 expression with progression of the tumor.

METHODS: Immunohistochemical method was used to examine the expression of CDw75 in 72 cases of the gastric carcinoma and adjacent normal gastric mucosa, and the percentage of the cells positively stained with CDw75 was calculated using a computer-aided microscopic image analysis system.

RESULTS: CDw75 was not expressed in normal gastric mucosa but detected in 37 of the 72 neoplastic gastric lesions. The expression of CDw75 was associated with the tumor progression as indicated by its close correlation with the depth of the tumor infiltration (χ² = 18.415, P < 0.01), TNM stage (χ² = 10.419, P < 0.05) and lymph node metastasis (χ² = 6.675, P < 0.01). The overall survival rate of the patients with positive CDw75 expression (32.4%) was significantly lower than that of the patients without CDw75 expression (71.4%) (P < 0.01). There was no significant correlation between the expression of CDw75 and the sex and age and histological type of patients (P > 0.05).

CONCLUSION: These findings suggest that the expression of CDw75 is a significant histopathological marker for more advanced stage of gastric carcinoma and indicates a poor prognosis for the patients.

Risk factors for liver metastases after curative surgical procedures for gastric cancer: a prospective study of 208 patients treated with surgical resection

BACKGROUND

The aim of this study was to evaluate the risk of liver metastases after radical surgical treatment for gastric cancer, the potential risk factors involved, and the sensitivity of serum tumor markers during followup.

STUDY DESIGN

A total of 208 patients who had undergone curative resection for primary gastric cancer and a prospective followup protocol were studied. The association between clinicopathologic variables and hepatic recurrence was investigated using standard univariate methods and multivariate Cox regression analysis.

RESULTS

Mean followup time (+/- SD) for the entire patient population was 51 +/- 38 months (median 52 months) and was 88 +/- 24 months (median 81 months) for disease-free patients. Recurrence of gastric cancer was documented in 109 of 208 patients (52.4%). Liver metastases were found in 28 of 208 patients (13.5%); in most of these patients (82.1%) diagnosis was made within 2 years after surgical treatment. The estimated cumulative risk of liver metastases after 5 years was 16.4%. Cox regression analysis identified lymph node involvement (adjusted relative risk [RR] = 6.28, 95% confidence interval [CI] = 2.11 to 18.70, p = 0.001), preoperative positivity for CEA, CA 19-9, or CA 72-4 (RR = 5.18, 95% CI = 1.75 to 15.37, p = 0.003), and intestinal histotype (RR = 3.08, 95% CI = 1.06 to 8.96, p = 0.039) as independent predictors of hepatic recurrence. In 27 of 28 cases hepatic recurrence was associated with an increase in CEA, CA 19-9, or CA 72-4 serum levels above the cutoff, either before or at the time of the clinical diagnosis (sensitivity 96.4%).

CONCLUSIONS

Preoperative positivity for serum tumor markers, lymph node involvement, and intestinal histotype are risk factors for liver metastases after radical surgical treatment for gastric cancer. Postoperative measurement of serum tumor markers may be useful for an early diagnosis of hepatic recurrence during followup.