Loss of ABH antigen expression in bladder cancer is not caused by loss of heterozygosity of the ABO locus

Regulation of ABO blood group antigen expression by miR-331-3p and miR-1908-5p during hematopoietic stem cell differentiation

The ABO blood group system is the most important factor in clinical transfusion medicine and is implicated in a number of human diseases. ABO antigens are not confined to red blood cells (RBCs) and are widely expressed in a variety of human cells and tissues. To date, many alleles with variant ABO expression have been identified and in many cases traced to one of the >250 reported genetic variations in the respective glycosyltransferase. The role of microRNAs (miRNAs) in the regulation of blood group antigens during erythropoiesis has not been addressed, however. Here, we show that miR-331-3p and miR-1908-5p directly target the mRNA of glycosyltransferases A and B. Expression levels of miR-331-3p and miR-1908-5p inversely correlated with levels of blood group A antigen. In addition, we found that overexpression of these miRNAs in hematopoietic stem cells led to a significantly reduced number of blood group A antigens per RBC. Simultaneous targeting of the transcription factor (TF) SP1 by miR-331-3p further enhanced these effects. The targeting rendered SP1 incapable of binding to the ABO gene promoter, causing further downregulation of blood group A antigen expression by up to 70%. Taken together, expression changes in these miRNAs may account for rare cases of weak A/B phenotypes that genetic variations in the glycosyltransferase coding region cannot explain. These results also suggest an explanation for the disappearance of ABH antigens during carcinogenesis and point to new therapeutic targets in ABO mismatched organ transplantation.

ABO blood type and the risk of cancer - Findings from the Shanghai Cohort Study

ABO blood type is an inherited characteristic. The associations between ABO blood type and risk of all cancer and specific cancers were examined in a prospective cohort study of 18,244 Chinese men enrolled in 1986. During the 25 years of follow-up, 3,973 men developed cancer including 964 lung cancers, 624 colorectal cancers, 560 gastric cancers, 353 liver cancers, and 172 urinary bladder cancers. Hazard ratios (HR) for all cancer and specific cancers by ABO blood type were calculated using Cox proportional hazards models. Compared with blood type A, blood type B was associated with statistically significant reduced risk of all cancers (HR, 0.91, 95% CI:0.84, 0.99). Both blood types B and AB were associated with significantly lower risk of gastrointestinal cancer and colorectal cancer, respectively. Blood type B was also associated with significantly lower risk of stomach cancer and bladder cancer, while blood type AB was associated with significantly increased risk of liver cancer. By histological type, blood types B and AB were associated with lower risk of epidermoid carcinoma and adenocarcinoma, but were not associated with risk of sarcoma, lymphoma, leukemia or other cell types of cancer. The findings of this study support a role of genetic traits related to ABO blood type in the development of cancers in the gastrointestinal and urinary tracts.

Loss of blood group A antigen expression in bladder cancer caused by allelic loss and/or methylation of the ABO gene

Loss of ABO blood group antigen expression has been reported in transitional cell carcinoma (TCC) of the bladder. Synthesis of the ABO blood group antigen was genetically determined by allelic variants of the ABO gene assigned on 9q34.1. We analyzed loss of heterozygosity (LOH) and promoter hypermethylation of the ABO gene in TCC and compared them with alterations of A antigen expression in TCC, dysplasia and normal urothelium. A total of 81 samples of TCC of the bladder obtained from transurethral resection (TUR) (n=44) and radical cystectomy (n=37) were examined. Expression of the A antigen was evaluated by immunohistochemical staining (IHC) using anti-A antigen monoclonal antibody. LOH of the ABO gene locus was examined by blunt-end single-strand DNA conformational polymorphism (SSCP) analysis using flouresence-based auto sequencer. Promoter hypermethylation of the ABO gene were examined by bisulfite PCR-SSCP (BiPS) analysis and/or methylation-specific PCR (MSP). Loss of A allele and/or hypermethylation were significantly associated with abnormal expression of the A antigen in cases undergoing TUR (P=0.02) and radical cystectomy (P=0.0005). For the analysis of the concomitant dysplasia in 23 cases with TCC of the bladder, the expression of the A antigen was maintained, regardless of the A allelic loss or methylation status in the tumor. In conclusion, A allelic loss and hypermethylation in the promoter region of the ABO gene showed significant correlation with reduction of A antigen expression in TCC, while the expression of the A antigen is maintained in concomitant dysplasia or normal urothelium, suggesting that loss of the ABO gene and/or its promoter hypermethylation is a specific marker for TCC.

Histo-blood group ABO antigen in oral potentially malignant lesions and squamous cell carcinoma--genotypic and phenotypic characterization

Loss of histo-blood group A/B antigens is frequent in oral cancer. It is unclear whether this alteration is due to loss of the chromosomal region encoding the genes. The aim was to investigate genotypic alterations in the ABO locus in oral potentially malignant lesions and carcinomas. Seventy-three cases which expressed A/B antigen in normal epithelium by immunohistochemical (IHC) staining were investigated. Both tumour and normal cells were collected from paraffin-embedded tissue by laser microdissection. DNA was extracted and analysed by PCR coupled with restricted digestion analysis in order to establish the ABO genotype. Total and patchy loss of A/B antigen expression was found in 24/32 carcinomas, 6/7 leukoplakias with severe dysplasia, 12/17 leukoplakias with mild and moderate dysplasia, and 6/17 leukoplakias without dysplasia. Specific A/B allele loss was found in 8/24 cases with carcinoma and 3/24 cases with mild and moderate dysplasia by genotyping analysis. O allele loss was found in 10 cases involving all four groups. In patients with heterozygous genotypes, A/B allelic loss by genotyping analysis was always followed by loss of A/B antigen expression by IHC staining. Loss of A/B antigen expression in tissues which had intact ABO alleles was, however, found and may be explained by other genetic and epigenetic changes.

ABH and Lewis histo-blood group antigens in cancer

Antigens of the ABH and Lewis histo-blood group family can be found on many normal cells, mainly of epithelial type. In carcinomas, altered expression of the various carbohydrate epitopes of this family occur, and are often strongly associated with either a good or bad prognosis. A review of the available data on these tumor-associated markers, their biosynthesis and their prognostic value is proposed here. For a long time it has been unclear whether their presence could affect the behavior of carcinoma cells. Recent data, however, indicate that they play biological roles in the course of tumor progression. The presence of sialyl-Le(a) or sialyl-Le(x), which are ligands for selectins, promotes the metastatic process by facilitating interaction with the endothelium of distant organs. The loss of A and B antigens increases cellular motility, while the presence of H epitopes increases resistance to apoptosis by mechanisms that remain to be defined. The Le(y) antigen has procoagulant and angiogenic activities. All these observations are used to present a model that may account for the described associations between the presence or loss of these markers and the outcome of disease. Finally, their potential clinical applications as tumor-associated markers or as targets of immunotherapy are reviewed.

Four tumor suppressor loci on chromosome 9q in bladder cancer: evidence for two novel candidate regions at 9q22.3 and 9q31

The most common genetic alteration identified in transitional cell carcinoma (TCC) of the bladder is loss of heterozygosity (LOH) on chromosome 9. However, localization of tumor suppressor genes on 9q has been hampered by the low frequency of subchromosomal deletions. We have analysed 139 primary, initial low stage TCC of the bladder using a panel of 28 microsatellite markers spanning chromosome 9 at an average distance of 5 Mb, following a primer-extension preamplification (PEP) technique. Sixty-seven (48%) tumors showed LOH at one or more loci and partial deletions were detected in 62 (45%) tumors; apparent monosomy 9 was detected in only five (4%) tumors. Deletions were more frequent on 9q (44%) than on 9p (23%), the latter being mostly associated with 9q deletion, suggesting that alteration of genes on 9q may be an early event associated with superficial papillary tumors. Combined data from the cases with partial 9q deletions displayed four candidate regions for tumor suppressor loci, based on the frequency of deletion observed and tumors with unique deletions at these sites. In two tumors, the unique partial deletion comprised D9S12 at 9q22.3, a region encompassing loci for the Gorlin syndrome and multiple self-healing squamous epithelioma gene. In two other tumors, the single LOH was identified at the D9S172 locus at 9q31-32 where the dysautonia and Fukuyama-type congenital muscular dystrophy genes have been located. One tumor showed unique LOH at the GSN locus at 9q33, a region frequently deleted in other sporadic tumors while the fourth region of deletion was observed at 9q34 between ASS and ABL-1, in two tumors. This region is frequently deleted in tumors and encompasses the locus for the hereditary hemorrhagic telangiectasia gene. These findings suggest four target regions on 9q within which suppressor genes for TCC may reside.

Genotypic and phenotypic characterization of the histoblood group ABO(H) in primary bladder tumors

The ABO(H) histoblood group genes have been mapped by linkage analysis to 9q34.1-34.2, an area of common deletions in bladder cancer. Lack of ABO(H) antigen expression in bladder tumors is a frequent and well-documented event. In bladder neoplasms the loss of A and B transferase activity is due to down-regulation of the ABO gene transcripts. Our study was undertaken in order to determine the presence of structural alterations of the ABO(H) gene-encoding locus in primary bladder tumors, to estimate the extent of allelic deletions and to characterize further the pattern of histoblood group antigen expression. Fifty-three primary bladder tumors were analyzed by immuno-histochemistry (IHC) using a panel of well-characterized antibodies and fresh frozen tissue sections. Normal and tumor DNA also were analyzed by PCR coupled with restriction enzyme analysis in order to establish the ABO genotype. Results obtained from these analyses were then compared to allelotyping data at the 9q34.1-4 region by Southern blotting. IHC data showed undetectable levels of antigen expression on neoplastic cells in 59% of informative cases. PCR-based genotypic results revealed allelic losses in 27% of heterozygous cases. Four of the 16 pheno- and/or genotypically altered cases (25%) presented loss of heterozygosity at D9S10 or D9S7 loci. Our data indicate that the lack of ABO antigen expression in certain bladder tumors is due to the allelic loss of the ABO glycosyltransferase-encoding genes and that in some of these tumors the loss involves the surrounding chromosomal region at 9q34.1-4.