Analysis of the influence of two CD24 genetic variants in Crohn's disease and ulcerative colitis

A Dinucleotide Deletion in the CD24 Gene Is a Potential Risk Factor for Colorectal Cancer

BACKGROUND

CD24 is a sialoglycoprotein anchored to the cell surface via glycosylphosphatidylinositol and is involved in intracellular signaling processes. It plays an important role in the early stages of the multistep process of colorectal carcinogenesis. Several single nucleotide polymorphisms in the CD24 gene are reported to exert a diverse effect on cancer risk. We aimed to elucidate whether CD24 TG/del genetic variants are associated with susceptibility to colorectal cancer (CRC).

METHODS

The study included 179 subjects, 36 with CRC (prior to surgery) and 143 healthy control subjects. Deoxyribonucleic acid was purified from peripheral blood leukocytes, and by using restriction fragment length polymorphism analysis, the CD24 gene was genotyped for the specific genetic variant, TG deletion. Additionally, CD24 protein expression levels were determined by Western blotting analysis.

RESULTS

The incidence of the TG/del was higher among the CRC patients compared with healthy controls, 14% and 10%, respectively (P = .54). CD24 protein levels were significantly higher among CRC patients. There were no significant differences in CD24 expression between CRC patients at different stages of the disease or between patients who carry the mutation and those who did not.

CONCLUSIONS

CD24 genetic variant might be of clinical value for risk assessment as part of cancer prevention programs. Further study on larger populations is needed to validate the importance of this dinucleotide deletion in CRC development. Overexpression of CD24 protein occurs early along the multistep process of CRC carcinogenesis, and a simple blood sample based on CD24 expression on peripheral blood leukocytes can contribute to early diagnosis.

Evaluation of two functional CD24 polymorphisms in primary sclerosing cholangitis

Background: Primary sclerosing cholangitis (PSC) is a progressive liver disease and characterized by chronic inflammation, sclerosis and strictures of bile ducts. Several genetic risk factors might contribute to pathogenesis. Functional single nucleotide polymorphisms (SNPs) in the CD24 gene have been associated with the development of autoimmune and autoinflammatory diseases and might contribute to the susceptibility for inflammatory bowel disease (IBD).Aim: This retrospective study aimed to evaluate the impact of two functional CD24 SNPs on clinical features and disease progression in patients with PSC.Methods: A C to T coding polymorphism (rs8734) and a TG deletion in the 3´- untranslated region (rs3838646) were genotyped. The study cohort comprises of 359 PSC patients for rs3838646 genotype and 335 PSC patients for rs8734 genotype. Clinical and laboratory parameters were collected by chart review.Results: For the rs8734 genotype, 175 patients (52.2%) were found to be homozygous wildtype ('Ala/Ala'), 127 (37.9%) patients were heterozygous ('Ala/Val') and 33 patients (9.9%) were homozygous mutant ('Val/Val'). The rs8734genotype was associated with a decreased risk for dominant strictures at first diagnosis of PSC (p = .04). For the rs3838646 genotype, 322 patients (89.7%) were found to be homozygous wildtype ('TG/TG'); 37 showed the 'TG/del' genotype (10.3%). The 'TG/del'genotype was associated with alower risk of IBD (p = .01).There was no influence of both CD24 SNPs with clinical end points or transplantation-free survival in our PSC cohort.Conclusion: Our results suggest a mild association of the rs8734 CD24 genotype with dominant strictures at first diagnosis of PSC. The rs3838646 CD24 genotype is associated with a lower rate of IBD. Both SNPs seem to modulate the clinical phenotype without major pathogenetic importance for disease progression in PSC.

CD24 expression does not affect dopamine neuronal survival in a mouse model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative condition that is characterised by the loss of specific populations of neurons in the brain. The mechanisms underlying this selective cell death are unknown but by using laser capture microdissection, the glycoprotein, CD24 has been identified as a potential marker of the populations of cells that are affected in PD. Using in situ hybridization and immunohistochemistry on sections of mouse brain, we confirmed that CD24 is robustly expressed by many of these subsets of cells. To determine if CD24 may have a functional role in PD, we modelled the dopamine cell loss of PD in Cd24 mutant mice using striatal delivery of the neurotoxin 6-OHDA. We found that Cd24 mutant mice have an anatomically normal dopamine system and that this glycoprotein does not modulate the lesion effects of 6-OHDA delivered into the striatum. We then undertook in situ hybridization studies on sections of human brain and found-as in the mouse brain-that CD24 is expressed by many of the subsets of the cells that are vulnerable in PD, but not those of the midbrain dopamine system. Finally, we sought to determine if CD24 is required for the neuroprotective effect of Glial cell-derived neurotrophic factor (GDNF) on the dopaminergic nigrostriatal pathway. Our results indicate that in the absence of CD24, there is a reduction in the protective effects of GDNF on the dopaminergic fibres in the striatum, but no difference in the survival of the cell bodies in the midbrain. While we found no obvious role for CD24 in the normal development and maintenance of the dopaminergic nigrostriatal system in mice, it may have a role in mediating the neuroprotective aspects of GDNF in this system.

CD24 genetic variants contribute to overall survival in patients with gastric cancer

AIM

To investigate the role of single nucleotide polymorphisms (SNPs) in CD24 gene in susceptibility and overall survival of gastric cancer (GC).

METHODS

We genotyped 3 tagging SNPs of CD24-P-534 in the promoter region, P170 in the coding region of exon 2 and P1527 in the 3' untranslated region - using polymerase chain reaction-restriction fragment length polymorphism in specimens from 679 histologically-confirmed GC cases, 111 gastric atrophy (GA) cases and 976 tumor-free controls. Serum immunoglobulin G antibodies to Helicobacter pylori (H. pylori) of all subjects were detected by enzyme-linked immunosorbent assay. CD24 expression was evaluated by immunohistochemistry in 131 GC specimens. Correlations between SNPs and risk of GC or GA were shown by P values and odd ratios (ORs) with 95% confidence intervals (95%CI) compared with the most common genotype of each SNP using the unconditional logistic regression model after adjusting for age, sex and H. pylori infection. Survival within each SNP group was plotted by Kaplan-Meier method and compared by log-rank test (recessive model). Hazard ratios with 95%CIs were computed by Cox regression model after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy.

RESULTS

All of the three loci were in Hardy-Weinberg equilibrium in the control group. Median follow-up time for the 600 GC patients included in the survival analysis was 36.2 mo (range, 2.1-66.7 mo; 95%CI: 34.3-36.5 mo). Patients with the P-534 A/A genotype had significantly shorter survival (HR = 1.38, 95%CI: 1.01-1.88, P = 0.042) than did the C/C or C/A genotype carriers after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy. This trend was more evident in patients who lived longer than 2.5 years (HR = 7.55, 95%CI: 2.16-26.32, P = 0.001). The P170 T/T genotype was associated with a shorter lifespan than the non-T/T genotypes, but not significantly so. None of the three genetic variants was found to be associated with risk of GC (including tumor stage, grade and distant metastasis) or with risk of gastric atrophy. Furthermore, no difference of CD24 expression was found among the genotypes.

CONCLUSION

The P-534 site in CD24 gene affects the overall survival of gastric cancer and may serve as a prognostic marker for gastric cancer.

Polymorphisms of the CD24 Gene Are Associated with Risk of Multiple Sclerosis: A Meta-Analysis

CD24 is a cell-surface protein mainly expressed in cells of the immune and central nervous system (CNS), cells that play a critical role in the development of multiple sclerosis (MS). In the current study, we investigated four polymorphisms of the CD24 gene regarding their associations with MS. To this end, univariate and multivariate meta-analysis were applied along with modifications to include data from family-trios so as to increase the robustness of the meta-analysis. We found that the polymorphism 226 C>T (Ala57Val) of the CD24 gene is associated with MS according to the recessive mode of inheritance (odds ratio = 1.75; 95% CI: 1.09, 2.81). Moreover, the 1527–1528 TG>del polymorphism is inversely associated with MS according to the dominant mode of inheritance (odds ratio = 0.57; 95% CI 0.39, 0.83). Conversely, the 1056 A>G and 1626 A>G polymorphisms were not found to be associated with MS. We conclude that the CD24 226 C>T polymorphism increases the risk of MS, while the 1527–1528 TG>del polymorphism seems to have a protective role against MS, suggesting that these two polymorphisms can be used as predictive biomarkers for MS development.

Associations between CD24 gene polymorphisms and inflammatory bowel disease: A meta-analysis

AIM: To evaluate the relationships between CD24 gene polymorphisms and the risk of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn’s disease (CD).

METHODS: The PubMed, Web of Science and Cochrane Library databases were searched (up to May 30, 2014). The search terms “CD24”, “inflammatory bowel disease”, “Crohn’s disease”, “Ulcerative colitis”, “IBD”, “CD” or “UC”; and “polymorphism”, “mutation” or “variant” were used. Association studies were limited to the English language, but no limitations in terms of race, ethnicity or geographic area were employed. Stata SE12 software was used to calculate the pooled odds ratios (ORs) with 95% confidence intervals (CIs). P < 0.05 was considered statistically significant. The information was independently extracted from each eligible study by two investigators. Two common polymorphisms, C170T (rs8734) and TG1527del (rs3838646), in the CD24 gene were assessed.

RESULTS: A total of three case-control studies including 2342 IBD patients and 1965 healthy controls were involved in this meta-analysis. The patients and controls were from Caucasian cohorts. The three articles included in this meta-analysis all conformed to Hardy-Weinberg equilibrium. This meta-analysis revealed that there were no significant associations between the two CD24 polymorphisms and the risk for IBD (all P > 0.05). However, in a disease subgroup analysis, we found that the CD24 C170T polymorphism was associated with an increased risk of UC in a dominant model (OR = 1.79, 95%CI: 1.15-2.77, P = 0.009) and an additive model (OR = 1.87, 95%CI: 1.19-2.93, P = 0.007), but this relationship was not present for CD. The CD24 TG1570del polymorphism was significantly associated with CD in the additive model (OR = 1.24, 95%CI: 1.01-1.52, P = 0.037).

CONCLUSION: Our findings provide evidence that the CD24 C170T polymorphism might contribute to the susceptibility to UC, and the CD24 TG1527del polymorphism might be associated with the risk of CD.

CD24 single nucleotide polymorphisms and cancer risk

Cluster of differentiation 24 (CD24) has been implicated in the development of cancer. Several single nucleotide polymorphisms (SNPs) in CD24 gene are reported to exert diverse effect on cancer risk. However, the association between CD24 SNPs and cancer risk remains unclear due to contradictory published findings. We performed a meta-analysis by pooling all available published studies on the susceptibility of CD24 rs52812045 and rs3838646 polymorphisms to cancer. The pooled odds ratios (ORs) with 95 % confidence intervals (95 % CIs) were calculated. There were five independent case-control studies with 5,539 cases and 10,241 controls included into the present study. The pooled results showed that no appreciable relationship was identified between any of the SNPs of CD24 and cancer risk. Interestingly, a protective role of the CD24 rs3838646 polymorphism was found in the risk of breast cancer, but lack of statistical significance (del allele vs. TG allele: OR = 0.89; 95 % CI, 0.79-1.01; P OR = 0.063; del/del vs.

TG/TG

OR = 0.70; 95 % CI, 0.44-1.12; P OR = 0.135; del/TG vs.

TG/TG

OR = 0.91; 95 % CI, 0.80-1.04, P OR = 0.180; del/del + del/TG vs.

TG/TG

OR = 0.90; 95 % CI, 0.79-1.03; P OR = 0.123; del/del vs. TG/TG + del/TG: OR = 0.69; 95 % CI, 0.44-1.08, P OR = 0.105). Our study firstly provides the evidence that SNPs (rs52812045 and rs3838646) of CD24 may not modify the risk of cancer. Nonetheless, more individual studies with high quality are needed for further elucidation.

Role of CD24 polymorphisms in the susceptibility to inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease (IBD) results from an inappropriate inflammatory response in which genetic, immune, and environmental factors all play important roles. Recently, single nucleotide polymorphisms (SNPs) in the CD24 gene have been associated with the development of several autoimmune diseases.

AIM

To evaluate whether CD24 SNPs, are associated with risk of ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

The CD24 polymorphisms C170T (rs8734), TG1527del (rs3838646), A1626G (rs1058881), and A1056G (rs1058818) were assessed in a case-control study of an Israeli cohort comprising 117 IBD patients and 105 age and gender-matched healthy controls. Restriction fragment length polymorphism (RFLP) analysis was performed using BstX1, Bsr1, Mfe1, and BstU1 restriction enzymes. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by logistic regression models.

RESULTS

Carriers of the C170T SNP were at increased risk of IBD (OR=3.022, 95% CI: 1.748-5.223, p=0.001), UC (OR=3.002, 95% CI: 1.661-5.427, p=0.001) and CD (OR=3.077, 95% CI: 1.334-7.095, p=0.008). Carrying the A1626G and A1056G SNPs was found to be a risk factor for IBD (OR=2.460, 95% CI: 1.420-4.259, p=0.001 and OR=1.856, 95% CI: 1.011-3.405, p=0.01), UC (OR=2.218, 95% CI: 1.207-4.075, p=0.01 and OR=1.944, 95% CI: 0.995-3.798, p=0.01) but not for CD (p=0.086 and p=0.299). The A1626G and TG1527del were found to be associated with younger age of IBD onset (p=0.022 and p=0.027, respectively).

CONCLUSIONS

The CD24 C170T polymorphism is associated with IBD risk. The A1626G and A1056G SNPs might be associated only with UC risk. These findings suggest CD24 as a new genetic susceptibility factor, with clinical implications in the prediction of IBD prognosis and therapy.

Genetic variants associated with Crohn's disease

Crohn’s disease is an immune-related disorder characterized by inflammation of the gastrointestinal mucosa, which can occur in any area throughout the digestive tract. This life-long disease commonly presents with abdominal pain, diarrhea, vomiting, and weight loss. While the exact etiology of this disease is largely unknown, it is thought to arise from an interaction between microbial, immunological, and environmental factors in a genetically susceptible host, whereby the immune system attacks the intestine as it cross reacts against gut microbial antigens. The study of genetic variants associated with Crohn’s disease has shed light on our understanding of disease pathophysiology. A large number of genetic variants identified in Crohn’s disease are related to genes targeting microbial recognition and bacterial wall sensing, the most common being NOD2/CARD15 gene. This review will discuss the recent advance in our knowledge of genetic variants of this disease and how they influence the disease course and prognosis.

NDRG2 down-regulation and CD24 up-regulation promote tumor aggravation and poor survival in patients with gallbladder carcinoma

Recent studies have demonstrated that N-Myc downstream-regulated gene 2 (NDRG2) may reduce the metastatic potential of breast cancer and hepatocellular carcinoma cells by regulating the expression of CD24, which is expressed in a large variety of solid tumors. The aim of this study was to clarify the clinical value of NDRG2 and CD24 expression in primary gallbladder carcinoma (GBC). One hundred and thirty GBC tissues were evaluated by immunohistochemistry for NDRG2 and CD24 expression. The associations of NDRG2 and CD24 expression with the clinicopathological characteristics and the overall survival of patients with GBC were analyzed. NDRG2 and CD24 were positively expressed in 49/130 (37.69%) and 107/130 (82.31%) of GBC tissues, respectively. In addition, the tumors with the down-regulation of NDRG2 and the up-regulation of CD24 more frequently had lymph node metastasis and lymphovascular invasion. Moreover, the tumors with the down-regulation of NDRG2 and the up-regulation of CD24 tended to show deeper invasion depth and higher TNM stage. There was a negative correlation between NDRG2 expression and CD24 expression in GBC tissues (r = -0.86, P < 0.001). The patients with NDRG2 negative expression correlated with poor prognosis of GBC (P = 0.01), as opposed to CD24 (P = 0.01). The survival rate of the patients with NDRG2-/CD24+ expression was the lowest (P < 0.001), and conjoined expression of NDRG2-/CD24+ was an independent prognostic indicator of GBC (P = 0.003). Our data suggest that NDRG2 down-regulation or CD24 up-regulation is an important feature of GBC. A combined detection of NDRG2/CD24 co-expression may benefit us in prediction of the prognosis in GBC.

Common cancer stem cell gene variants predict colon cancer recurrence

PURPOSE

Recent evidence suggests that cancer stem cells (CSC) are responsible for key elements of colon cancer progression and recurrence. Germline variants in CSC genes may result in altered gene function and/or activity, thereby causing interindividual differences in a patient's tumor recurrence capacity and chemoresistance. We investigated germline polymorphisms in a comprehensive panel of CSC genes to predict time to tumor recurrence (TTR) in patients with stage III and high-risk stage II colon cancer.

EXPERIMENTAL DESIGN

A total of 234 patients treated with 5-fluorouracil-based chemotherapy at the University of Southern California were included in this study. Whole blood samples were analyzed for germline polymorphisms in genes that have been previously associated with colon CSC (CD44, Prominin-1, DPP4, EpCAM, ALCAM, Msi-1, ITGB1, CD24, LGR5, and ALDH1A1) by PCR-RFLP or direct DNA-sequencing.

RESULTS

The minor alleles of CD44 rs8193 C>T, ALCAM rs1157 G>A, and LGR5 rs17109924 T>C were significantly associated with increased TTR (9.4 vs. 5.4 years; HR, 0.51; 95% CI: 0.35-0.93; P = 0.022; 11.3 vs. 5.7 years; HR, 0.56; 95% CI: 0.33-0.94; P = 0.024, and 10.7 vs. 5.7 years; HR, 0.33; 95% CI: 0.12-0.90; P = 0.023, respectively) and remained significant in the multivariate analysis stratified by ethnicity. In recursive partitioning, a specific gene variant profile including LGR5 rs17109924, CD44 rs8193, and ALDH1A1 rs1342024 represented a high-risk subgroup with a median TTR of 1.7 years (HR, 6.71, 95% CI: 2.71-16.63, P < 0.001).

CONCLUSION

This is the first study identifying common germline variants in colon CSC genes as independent prognostic markers for stage III and high-risk stage II colon cancer patients.