Clinicopathologic evaluation of CDw75 antigen expression in patients with gastric carcinoma

Sialylated glycoproteins and sialyltransferases in digestive cancers: Mechanisms, diagnostic biomarkers, and therapeutic targets

Sialic acid (SA), as the ultimate epitope of polysaccharides, can act as a cap at the end of polysaccharide chains to prevent their overextension. Sialylation is the enzymatic process of transferring SA residues onto polysaccharides and is catalyzed by a group of enzymes known as sialyltransferases (SiaTs). It is noteworthy that the sialylation level of glycoproteins is significantly altered when digestive cancer occurs. And this alteration exhibits a close correlation with the progression of these cancers. In this review, from the perspective of altered SiaTs expression levels and changed glycoprotein sialylation patterns, we summarize the pathogenesis of gastric cancer (GC), colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), and hepatocellular carcinoma (HCC). Furthermore, we propose potential early diagnostic biomarkers and prognostic indicators for different digestive cancers. Finally, we summarize the therapeutic value of sialylation in digestive system cancers.

Disease-free survival of colorectal cancer patients in relation to CDw75 antigen expression

OBJECTIVE

CDw75 is an α(2,6)-sialylated antigen associated with a poor prognosis in gastric cancer. In the present study, we examined if CDw75 expression in colorectal cancer (CRC) predicts tumour recurrence. Besides, we evaluated CDw75 expression in different colorectal tissue specimens to clarify their role in tumour development and progression.

METHODS

We analyzed CDw75 expression in 34 specimens of healthy disease-free colorectal mucosa, 19 specimens of inflammatory colorectal mucosa, 73 colorectal adenomas, 35 specimens of healthy tissue and 101 specimens of tumoural tissue from CRC patients.

RESULTS

None of the healthy disease-free and inflammatory colorectal mucosa specimens showed the presence of the epitope. CDw75 was expressed in 26% of the colorectal adenomas. In healthy and tumoural tissue from CRC patients, CDw75 was detected in 22.9% and 82.2% of the specimens, respectively. CDw75 expression in tumoural tissue was correlated with growth pattern (p = 0.044), Dukes stage (p = 0.002), TNM stage (p = 0.020) and distant metastasis (p = 0.005). Survival analysis showed that CDw75 expression is not associated with tumour recurrence.

CONCLUSION

CDw75 expression in CRC is not a prognostic factor for predicting disease-free survival. Nevertheless, CDw75 expression may be a good marker of tumour progression and of the malignant potential of CRC.

Synthesis and expression of CDw75 antigen in human colorectal cancer

Background

Increased ST6Gal I activity has been associated with the α(2,6)sialylation enhancement of membrane glycoconjugates observed in metastatic colorectal carcinomas (CRC). Siaα(2,6)Galβ(1,4)GlcNAc sequence, known as CDw75, is a sialylated carbohydrate determinant generated by the ST6Gal I. This epitope has been reported to be associated with the progression of gastric and colorectal tumours, hence there are only a few conclusive studies to date.

Methods

By radioisotopic techniques we evaluated the ST6Gal I activity in healthy, transitional and tumour tissues from 43 patients with CRC. By immunohistochemistry we assessed the CDw75 expression in 25 colorectal adenomas, 43 tumours, 13 transitional and 28 healthy tissues of CRC patients.

Results

ST6Gal I activity was likewise found to be statistically higher in tumour tissue respect to healthy tissue from CRC patients. CDw75 expression was positive in 20% of colorectal adenomas. Furthermore, 70% of tumour specimens and 8.3% of transitional specimens were positive for CDw75 expression, whereas none of the healthy ones showed the presence of the epitope.

Conclusion

The major contribution of this study is the inclusion of data from transitional tissue and the analysis of CDw75 antigen expression in CRC and in colorectal adenomas, little known so far. ST6Gal I activity and CDw75 antigen expression were increased in CRC. Although their comparison did not reach the statistical significance, a great extent of patients showed both, an enhanced tumour ST6Gal I activity and an increased CDw75 expression in the tumour tissue. So, these two variables may play a role in malignant transformation. The expression of CDw75 in colorectal adenomas suggests that this antigen may be a tumour marker in CRC.

Elevation of ST6Gal I activity in malignant and transitional tissue in human colorectal cancer

OBJECTIVES

The aim of the present study was to investigate the activity of CMP-NeuAc:Galbeta(1,4)GlcNAc sialyltransferase (ST6Gal I) in colorectal cancer (CRC).

METHODS

ST6Gal I activity was determined in healthy, transitional and tumor tissues from the same patient using asialotransferrin and N-acetyllactosamine as acceptors.

RESULTS

ST6Gal I activities with asialotransferrin (n = 85) and N-acetyllactosamine (n = 40) as acceptors were statistically significantly enhanced in CRC tissue compared with healthy mucosa from the same patient (p = 0.001). Using transitional tissue (n = 27), enhancement versus healthy tissue was observed (p < 0.05). A positive correlation was found between ST6Gal I activity with N-acetyllactosamine and asialotransferrin in healthy (n = 32), tumorous (n = 32) and transitional tissue (n = 27), supporting the fact that the same enzyme was detected using both acceptors. Furthermore, we studied the relationship between some patients' clinicopathological features and ST6Gal I activity. Although the differences were not statistically significant, the levels of ST6Gal I activity in tumorous and transitional tissues varied with the histological grade of the tumor; however, we failed to find a correlation with the AJCC tumor classification.

CONCLUSIONS

This work reports enhanced ST6Gal I activity in tumor and transitional tissues from CRC patients. However, our overall results suggest that ST6Gal I activity is not indicative of the patient's outcome.

Clinical relevance of sialyltransferases ST6GAL-I and ST3GAL-III in gastric cancer

Aberrant glycosylation of membrane components due to specific alterations of glycosyltransferase activity is a common feature of carcinoma cells and is usually associated with invasion and metastasis. In a prospective study, the enzyme activity of the sialyltransferases ST6GAL-I and ST3GAL-III was studied in gastric cancer and normal mucosa in 55 patients by a radiometric assay. Cellular localization of sialyltransferase ST6GAL-I mRNA expression was studied by in situ hybridization. Sialyltransferase ST6GAL-I mRNA expression was mainly localized to epithelial cells. ST6GAL-I enzyme activity was enhanced within the tumor tissue. Significant correlations were found between the presence of signet ring cells and enhanced ST6GAL-I activity in the tumor tissue (p = 0.047) or in the mucosa (p = 0.024), and between signet ring cells and ST3GAL-III activity in the mucosa (p < 0.001). Multivariate Cox analysis demonstrated that only lymph node metastases (p = 0.044) had a significant influence on tumor-related survival. ST3GAL-III and ST6GAL-I activity showed no independent prognostic relevance in multivariate analysis, but high levels of ST3GAL-III and ST6GAL-I in the tumor tissue correlated with secondary local tumor recurrence (p = 0.005; p = 0.012). Interestingly, also the nonmalignant and uninvolved mucosa of tumor patients was altered on the molecular level and in some cases showed enhanced sialyltransferase levels indicative of the alteration of glycosylation very early during tumorigenesis.

Enhanced expression of alpha 2,6-sialyltransferase ST6Gal I in cervical squamous cell carcinoma

OBJECTIVE

Increased messenger ribonucleic acid (mRNA) expression of beta-galactoside alpha 2,6-sialyltransferase I (ST6Gal I) is important in squamous cell carcinoma (SCC) of the cervix. In many tissues, ST6Gal I is transcriptionally regulated through the use of promoters that originate in the mRNA species that diverge in the 5'-untranslated regions. To clarify the roles of ST6Gal I mRNA species in cervical SCC, we investigated their expression, including a "constitutive" promoter (placental or Y + Z form), "hepatic" promoter (H form), and a specific lymphoblastic promoter (X form), in normal and SCC tissues of the cervix using real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR).

METHODS

Expression of the ST6Gal I species was investigated in normal cervical tissue samples (n = 38) and FIGO IB1 cervical SCC samples (n = 38) by relatively quantitative real-time RT-PCR, using primers designed for amplification of a portion of the coding region common to all mRNA species or ones for amplification of the placental transcript, the hepatic transcript, or lymphoblastic transcript.

RESULTS

ST6Gal I mRNA expression was significantly increased in cancerous tissues compared to that in normal tissues (P = 0.004, Mann-Whitney U test; P < 0.001, paired t test). Expression of the Y + Z form did not appear to be affected by cancer transformation, since it was detected at comparable levels in normal and cancerous tissues (P = 0.986), but H form expression was significantly enhanced in cancerous tissues compared to that in normal tissues (P < 0.001, Mann-Whitney U test and paired t test). Surprisingly, the X form could be detected in some patients with and without cancer, but the detection rate was significantly higher in patients with cancer (86.8% vs 52.6%, respectively; P = 0.021, Fisher's exact test). Although the X transcript was detected at a low level compared to the H and Y + Z transcripts, its expression was also significantly enhanced in patients with cancers compared to those without cancers (P < 0.001, Mann-Whitney U test and paired t test).

CONCLUSIONS

An increased level of hepatic transcripts may be important in cancer transformation because the transcripts contribute to enhance ST6Gal I expression in cancerous tissues.

Expression of sialyltransferase family members in cervix squamous cell carcinoma correlates with lymph node metastasis

OBJECTIVE

Altered messenger ribonucleic acid (mRNA) expression of the four sialyltransferases (STs including ST3Gal I, ST3Gal III, ST3Gal IV, and ST6Gal I) is important in squamous cell carcinoma of the cervix. This study further investigates their changes in mRNA expression of the four STs in FIGO stage IB1 squamous cell carcinoma to assess the extent of sialylation associated with lymph node metastases.

METHODS

Alterations in ST mRNA expression in FIGO IB1 cervical squamous cell carcinomas (n = 79) were examined by semiquantitative reverse transcription-polymerase chain reaction.

RESULTS

Both ST6Gal I mRNA and ST3Gal III mRNA expressions were significantly increased in patients with lymph node metastases compared to those without lymph node metastases (P = 0.002 and P = 0.001, respectively, Mann-Whitney U test). Using receiver operating characteristic curves of ST ratio index for accuracy comparison of lymph node metastases, ST3Gal III and ST6Gal I were observed to be fairly interchangeable (area under the curve (AUC) of 3Gal I = 0.810; AUC of 6Gal I = 0.786, significance of difference between AUC = 0.810). High ST6Gal I expression was associated with other invasive properties of cervical cancer, such as deep stromal invasion and presence of lymph-vascular space involvement. ST6Gal I expression seemed to be more enhanced in bigger tumors.

CONCLUSIONS

Our results suggested that ST3Gal III and ST6Gal I were of importance for the lymph node metastases in FIGO IB1 cervical cancer patients; more specifically, overexpression of ST6Gal I was of crucial relevance for the presence of poor prognostic factors, such as deep stromal invasion and lymph-vascular space involvement and lymph node metastases.

Clinicopathologic evaluation of CDw75 antigen expression in colorectal adenocarcinomas

CDw75, a B lymphocyte surface antigen, is a sialylated carbohydrate epitope, which is generated by the enzyme beta galactosyl alpha 2,6 sialyltransferase (Sia-T1). In colon carcinomas, although higher levels of Sia-T1 has been described and found to be correlated with metastatic potential of tumor cells, the expression of CDw75 antigen still remains unknown. To address this issue, we investigated immunohistochemically CDw75 antigen expression in 195 colorectal adenocarcinomas and their nodal metastases. The correlation between CDw75 antigen expression with selected clinicopathologic variables was analyzed by using Chi-square and Fisher s exact tests. Positive staining was observed in 101 cases. Non-neoplastic mucosa was negative consistently. The frequency of positivity was decreased according to the degree of differentiation (p<0.001). Antigen expression was found to be associated with deeper penetration (p<0.006), positive lymph nodes (p<0.001), distant metastases (p<0.006) and advanced stage (p<0.001). Same relationships were detected in well and moderately differentiated tumors when CDw75 immunoreactivity was evaluated in each histologic grade separately. Our findings indicate that CDw75 antigen expression may be a good indicator of the biological aggressiveness of colorectal adenocarcinomas especially in tumors with well and moderately differentiated morphology.