Correlation of expression of ABH blood group carbohydrate antigens with metastatic potential in human lung carcinomas

We have investigated the regulatory role of DNA methylation in the expression of the human histo-blood group ABO genes. The ABO gene promoter region contains a CpG island whose methylation status correlates well with gene expression in the cell lines tested. The CpG island was found hypomethylated in some cell lines that expressed ABO genes, whereas the other cell lines that did not express ABO genes were hypermethylated. The ABO blood group system discovered by Karl Landsteiner (1) at the beginning of this century is of great importance in blood transfusions and organ transplantations. Two carbohydrate antigens, A-and B-antigens, and their antibodies constitute this system. The A and B functional alleles at the ABO genetic locus encode glycosyltransferases ␣133GalNAc transferase (designated A-transferase) and ␣133Gal transferase (designated B-transferase), respectively. A-transferase transfers a GalNAc residue from UDP-GalNAc to the precursor H substrate, producing A antigens as defined by the trisaccharide determinant structure, GalNAc␣133(Fuc␣132)Gal␤13 R. Similarly, B-transferase catalyzes the transfer of a Gal from UDP-Gal to the same H substrate, producing B antigens defined by Gal␣133(Fuc␣132)Gal␤13 R (2-5). Molecular genetic studies of the human ABO genes have identified two critical single base substitutions that result in amino acid substitutions responsible for the different donor nucleotidesugar substrate specificity between A-and B-transferases. A single base deletion, which shifts the reading frame of codons and abolishes the function of A-transferase, has been identified in most O alleles (6, 7).The ABO genes are expressed in a cell type-specific manner; the isoantigens A, B, and H of blood groups A, B, and O are not confined to red cells only but are also found in most secretions and on some epithelial cells. However, they are absent in connective tissues and the central nervous system (8). ABH antigens are known to undergo drastic changes during development, differentiation, and maturation of normal cells (9). In addition to these physiological processes, profound changes have also been documented in pathological processes such as tumorigenesis. Reduction or complete deletion of A/B antigen expression in bladder and oral cancers has been documented, as well as the apparent onco-developmental expression of the ABH antigens in gastric and distal colon tumors (10 -12). Moreover, the loss of ABH antigens has been correlated with tumor progression of various carcinomas including lung and bladder carcinomas (13-16). Thus, delineation of regulatory mechanism is essential to understand these complicated expression patterns of the ABO genes.In an initial attempt to elucidate the molecular mechanism controlling the expression of the human ABO genes, we isolated several genomic clones that covered the ABO genes over 18 kb 1 (17). A 4.7-kb EcoRI/NcoI 5Ј-upstream fragment flanking the coding sequence in exon 1 of the human ABO gene was subcloned into the promoterless pGL3-basic vector upstream of the lucifer...

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Expression of Human Histo-blood Group ABO Genes Is Dependent upon DNA Methylation of the Promoter Region

Kominato¹,

Hata²,

Takizawa³

et al. 1999

“…Reduction or complete deletion of A/B antigen expression in primary lung, bladder, and colorectal carcinomas have been reported. This phenotypic change was well correlated with the invasive and metastatic potentials of the tumors, and with 5-or 10-year mortality rates of the patients (10,11). Expression of H/Le y , the A/B precursor, was inversely correlated with the survival rate of the patients with lung carcinoma after surgery (12).…”

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confidence: 89%

Transcription of Human ABO Histo-blood Group Genes Is Dependent upon Binding of Transcription Factor CBF/NF-Y to Minisatellite Sequence

Kominato¹,

Tsuchiya²,

Hata³

et al. 1997

111

We have studied the transcriptional regulatory mechanism of the human histo-blood group ABO genes, and identified DNA cis-elements and trans-activating protein that control the expression of these genes which are important in blood transfusion and organ transplantation. We introduced the 5 -upstream sequence of ABO genes into the promoterless reporter vector and characterized the promoter activity of deletion constructs using transient transfection assays with gastric cancer cell line KATO III cells. The sequence just upstream of the transcription start site (cap site), and an enhancer element, which is located further upstream (between ؊3899 and ؊3618 base pairs ( Histo-blood group ABH(O) antigens, the major alloantigens in humans (1), have been characterized as defined trisaccharide determinants GalNAc␣133(Fuc␣132)Gal␤13 R, Gal␣133(Fuc␣132)Gal␤13 R, and disaccharide determinant Fuc␣132Gal␤13 R for A, B, and H, respectively (2, 3). These structures represent the secondary gene products which are synthesized from the precursor H substrate by ␣133GalNAc (A transferase) and ␣133Gal transferase (B transferase), the primary gene products coded by the functional alleles at the ABO locus (4, 5). Molecular genetic studies of the ABO genotypes have identified two critical single-base substitutions between A and B genes, the resultant 2-amino acid substitutions being responsible for the different donor nucleotide-sugar substrate specificity between A and B transferases. A single base deletion, which shifts the codon reading frame and abolishes the function of A transferase, has been identified in O allelic cDNAs (6, 7).ABH antigens are known to undergo drastic changes during development, differentiation, and maturation. Studies of these antigens in stratified squamous epithelia provided one of the clearest examples of differential expression during cell maturation (8). In non-keratinized stratified squamous epithelia, the immature cells in the basal layers are characterized by the expression of sialylated or unsubstituted precursor peripheral cores, while differentiated and mature cells in the upper layers sequentially express ␣132-fucosylated H structures, and A and B antigens depending on the ABO genotype of the individual. This sequential expression of carbohydrate antigens is associated with the differentiation pattern of the epithelium. An interesting question is how these changes are controlled during cell differentiation. Since keratinocytes are known to greatly change their gene expression during terminal cell differentiation (9), the switch-on of the ABO genes during the maturation may be governed by the same factor(s). To fill in the gap between the expression of the ABO genes and the appearance of the ABO phenotypes in the terminal differentiation of epithelial cells, it is essential to understand the transcriptional regulatory mechanism of the ABO genes. In addition to the normal cell differentiation process, the changes of ABH antigen expression have also been documented in abnormal processes such as tumorig...

“…Reduction or complete deletion of A/B antigen expression in primary lung, bladder, and colorectal carcinomas has been reported. This phenotypic change was well correlated with the invasive and metastatic potential of the tumors and with patient 5-or 10-year mortality rates (5,6).…”

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confidence: 99%

Epithelial Expression of Human ABO Blood Group Genes Is Dependent upon a Downstream Regulatory Element Functioning through an Epithelial Cell-specific Transcription Factor, Elf5

Sano

Nakajima

Takahashi

et al. 2016

The human ABO blood group system is of great importance in blood transfusion and organ transplantation. The ABO system is composed of complex carbohydrate structures that are biosynthesized by A-and B-transferases encoded by the ABO gene. However, the mechanisms regulating ABO gene expression in epithelial cells remain obscure. On the basis of DNase I-hypersensitive sites in and around ABO in epithelial cells, we prepared reporter plasmid constructs including these sites. Subsequent luciferase assays and histone modifications indicated a novel positive regulatory element, designated the ؉22.6-kb site, downstream from ABO, and this was shown to enhance ABO promoter activity in an epithelial cell-specific manner. Expression of ABO and B-antigen was reduced in gastric cancer KATOIII cells by biallelic deletion of the ؉22.6-kb site using the CRISPR/Cas9 system. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that the site bound to an epithelial cell-specific transcription factor, Elf5. Mutation of the Ets binding motifs to abrogate binding of this factor reduced the regulatory activity of the ؉22.6-kb site. Furthermore, ELF5 knockdown with shRNA reduced both endogenous transcription from ABO and B-antigen expression in KATOIII cells. Thus, Elf5 appeared to be involved in the enhancer potential of the ؉22.6-kb site. These results support the contention that ABO expression is dependent upon a downstream positive regulatory element functioning through a tissue-restricted transcription factor, Elf5, in epithelial cells.The human ABO blood group system is of great importance in blood transfusion and organ transplantation. The system comprises complex carbohydrate structures that are biosynthesized by the A-and B-transferases encoded by the A and B genes, respectively (1). The ABO genes consist of seven exons spanning more than 20 kb of genomic DNA, and two critical single-base substitutions in the last coding exon result in amino acid substitutions responsible for the difference in donor nucleotide sugar substrate specificity between A-and B-transferases (2). A single base deletion in exon 6 has been ascribed to a shift in the reading frame of codons and abolition of A-transferase activity in most O alleles. On the other hand, the distribution of the A-and B-antigens is cell type-specific; for example, the antigens are expressed on red blood cells and epithelial cells, as well as in salivary glands, although they are absent from the central nervous system, muscle, and connective tissue. Moreover, ABH antigens are known to be expressed during the maturation of erythroid and epithelial cells; for example, when erythroid cells differentiate in vitro, ABO is expressed at an undetectable level in the early phase, increases subsequently, and then decreases later (3, 4). In addition to the normal cell differentiation process, changes in ABH antigen expression have also been documented in abnormal processes such as tumorigenesis (1). Reduction or complete deletion of A/B antigen expressi...