FX enzyme and GDP-L-Fuc transporter expression in colorectal cancer.

AIMS: Fucosylation is regulated by fucosyltransferases, the guanosine diphosphate-L-fucose (GDP-L-Fuc) synthetic pathway, and the GDP-L-fucose transporter (GDP-L-Fuc Tr). We have reported previously an increased level of α(1,6)fucosyltransferase activity and expression in colorectal cancer (CRC). The present study aimed to analyse the expression profiles of the FX enzyme and GDP-L-Fuc Tr in a cohort of operated CRC patients to elucidate their role in α(1,6)fucosylation in this neoplasm. METHODS AND RESULTS: We assessed the immunohistochemical expression of FX and GDP-L-Fuc Tr in a series of tumour samples and healthy tissues from CRC specimens. FX expression was observed in 58 of 91 (63.7%) tumours and 23 of 28 (82.1%) corresponding healthy samples. GDP-L-Fuc Tr expression was detected in 86 of 102 (84.3%) colorectal tumours, and 13 of 27 (48.1%) healthy tissue specimens. The expression of GDP-L-Fuc Tr was statistically higher in tumours than in healthy tissues (P < 0.001). A correlation was found between FX and GDP-L-Fuc Tr expression in tumour samples (P = 0.003). CONCLUSION: GDP-L-Fuc Tr overexpression in the tumour tissue of CRC patients suggests that GDP-L-Fuc transport to the Golgi apparatus may be an important factor associated with increased α(1,6)fucosylation in CRC.

Identification of α(1,6)fucosylated proteins differentially expressed in human colorectal cancer.

BACKGROUND: A universal hallmark of cancer cells is the change in their glycosylation phenotype. One of the most frequent alterations in the normal glycosylation pattern observed during carcinogenesis is the enhancement of α(1,6)linked fucose residues of glycoproteins, due to the up-regulation of the α(1,6)fucosyltransferase activity. Our previous results demonstrated the specific alteration of this enzyme activity and expression in colorectal cancer, suggesting its implication in tumour development and progression. METHODS: In the current work we combined a LCA-affinity chromatography with SDS-PAGE and mass spectrometry in order to identify α(1,6)fucosylated proteins differentially expressed in colorectal cancer. This strategy allowed the identification of a group of α(1,6)fucosylated proteins candidates to be involved in CRC malignancy. RESULTS: The majority of the identified proteins take part in cell signaling and interaction processes as well as in modulation of the immunological response. Likewise, we confirmed the increased expression of GRP94 in colorectal cancer tissue and the significant down-regulation of the IgGFcBP expression in tumour cells. CONCLUSION: All these results validate the importance of core-fucosylated proteins profile analysis to understand the mechanisms which promote cancer onset and progression and to discover new tumour markers or therapeutic targets.

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 alpha(2,6)sialylation enhancement of membrane glycoconjugates observed in metastatic colorectal carcinomas (CRC). Siaalpha(2,6)Galbeta(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.

Expression and enzyme activity of alpha(1,6)fucosyltransferase in human colorectal cancer.

Changes in enzyme activity and the expression levels of alpha(1,6)fucosyltransferase [alpha(1,6)FT] have been reported in certain types of malignant transformations. To develop a better understanding of the role of alpha(1,6)FT in human colorectal carcinoma (CRC), we analysed the enzyme activity in healthy and tumour tissues. alpha(1,6)FT activity was considerably higher in tumour tissue than in healthy tissue and was related to gender, lymph node metastasis, type of growth and tumour stage. We also observed a significant increase in the alpha(1,6)FT expression in tumour tissues as compared to healthy and transitional tissues, inflammatory lesions and adenomas. The immunohistochemical expression in tumour tissues was correlated with the degree of infiltration through the intestinal wall. Finally, a statistical correlation was found between enzyme activity and expression obtained by Western blot in colorectal tumours when compared in the same patient. All these findings demonstrate an alteration of alpha(1,6)FT activity and expression in CRC.