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Beta-galactoside alpha2,6 sialyltransferase in human colon cancer: contribution of multiple transcripts to regulation of enzyme activity and reactivity with Sambucus nigra agglutinin.

Abstract：

:Colon cancer tissues display an increased activity of beta-galactoside alpha2,6 sialyltransferase (ST6Gal.I) and an increased reactivity with the lectin from Sambucus nigra (SNA), specific for alpha2,6-sialyl-linkages. Experimental and clinical studies indicate a contribution of these alterations to tumor progression, but their molecular bases are largely unknown. In many tissues, ST6Gal.I is transcriptionally regulated through the usage of different promoters that originate mRNAs diverging in the 5;-untranslated regions. RT-PCR analysis of 14 carcinoma samples, all expressing an increased ST6Gal.I enzyme activity, and of the corresponding normal mucosa revealed the presence of at least 2 transcripts. One, containing the 5;-untranslated exons, Y+Z, is thought to represent the "housekeeping" expression, and another previously described in hepatic tissues. Both the Y+Z and the hepatic transcripts were detectable in normal and cancer tissues but that latter form had a marked tendency to accumulate in cancer. The extent of alpha2,6-sialylation of glycoconjugates, as determined by SNA-dot blot analysis, was markedly enhanced in all cancer specimens, but the level of reactivity only partially correlated with the level of enzyme expression. Western blot analysis revealed a strikingly heterogeneous pattern of SNA reactivity among cancer tissues. These data indicate that: i) during neoplastic transformation of colonic cells, ST6Gal.I expression may be modulated through a differential promoter usage; ii) the extent of alpha2,6-sialylation of cancer cell membranes is not a direct function of the ST6Gal.I activity, strongly suggesting the existence of other, more complex mechanisms of regulation.

journal_name

Int J Cancer

journal_title

International journal of cancer

authors

Dall'Olio F,Chiricolo M,Ceccarelli C,Minni F,Marrano D,Santini D

doi

10.1002/1097-0215(20001001)88:1<58::aid-ijc9>3.0.c

keywords:

subject

Has Abstract

pub_date

2000-10-01 00:00:00

pages

58-65

issue

eissn

0020-7136

issn

1097-0215

pii

10.1002/1097-0215(20001001)88:1<58::AID-IJC9>3.0.C

journal_volume

pub_type

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Beta-galactoside alpha2,6 sialyltransferase in human colon cancer: contribution of multiple transcripts to regulation of enzyme activity and reactivity with Sambucus nigra agglutinin.