Two BRM promoter polymorphisms predict poor survival in patients with hepatocellular carcinoma

Genetic Polymorphisms in CD35 Gene Contribute to the Susceptibility and Prognosis of Hepatocellular Carcinoma

CD35, an important molecule implicated in inflammation and immunity, is reportedly associated with several cancers. However, very few studies have investigated the relationship between CD35 polymorphisms and hepatocellular carcinoma (HCC). The current study was conducted to investigate the association between tag SNPs in CD35 and HCC susceptibility and postoperative recurrence, in an attempt to elucidate the gene-environment interactions in HCC. A total of 1233 Chinese Han people, including 647 healthy controls and 586 HCC cases, were sampled in this study. Six Tag SNPs (rs10494885, rs2296160, rs3737002, rs3849266, rs669117, and rs7525160) of CD35 were selected using the HaploView 4.2 program and genotyped by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Overall, the mutation genotypes CC/CG of CD35 rs7525160 significantly increased the risk of HCC. Stratification analysis indicated that CD35 rs7525160 CC/CG genotypes increased HCC risk in patients younger than 65 years and were closely related to the pathological type of poor prognosis of HCC. Cox proportional hazard ratio model analysis revealed that the rs7525160 CC/CG genotype remains a significant independent risk factor for postoperative recurrence of HCC. In conclusion, CD35 rs7525160 polymorphism may contribute to the susceptibility and prognosis of HCC in the Chinese Han population.

HELLS serves as a poor prognostic biomarker and its downregulation reserves the malignant phenotype in pancreatic cancer

BACKGROUND

SMARCAs, belonged to SWI/SNF2 subfamilies, are critical to cellular processes due to their modulation of chromatin remodeling processes. Although SMARCAs are implicated in the tumor progression of various cancer types, our understanding of how those members affect pancreatic carcinogenesis is quite limited and improving this requires bioinformatics analysis and biology approaches.

METHODS

To address this issue, we investigated the transcriptional and survival data of SMARCAs in patients with pancreatic cancer using ONCOMINE, GEPIA, Human Protein Atlas, and Kaplan-Meier plotter. We further verified the effect of significant biomarker on pancreatic cancer in vitro through functional experiment.

RESULTS

The Kaplan-Meier curve and log-rank test analyses showed a positive correlation between SMARCA1/2/3/SMARCAD1 and patients' overall survival (OS). On the other hand, mRNA expression of SMARCA6 (also known as HELLS) showed a negative correlation with OS. Meanwhile, no significant correlation was found between SMARCA4/5/SMARCAL1 and tumor stages and OS. The knockdown of HELLS impaired the colony formation ability, and inhibited pancreatic cancer cell proliferation by arresting cells at S phase.

CONCLUSIONS

Data mining analysis and cell function research demonstrated that HELLS played oncogenic roles in the development and progression of pancreatic cancer, and serve as a poor prognostic biomarker for pancreatic cancer. Our work laid a foundation for further clinical applications of HELLS in pancreatic cancer.

WSB1 and IL21R Genetic Variants Are Involved in Th2 Immune Responses to Ascaris lumbricoides

Genetic and epigenetic factors are considered to be critical for host-parasite interactions. There are limited data on the role of such factors during human infections with Ascaris lumbricoides. Here, we describe the potential role of genetic factors as determinants of the Th2 immune response to A. lumbricoides in Brazilian children. Stool samples were collected from the children to detect A. lumbricoides by microscopy and peripheral blood leukocytes (PBLs) were cultured in whole blood cultures for detection of cytokines (IL-5, IL-10, and IL-13) in vitro. Levels of anti-A. lumbricoides IgE and IgG4 were measured in plasma. DNA was extracted from PBLs and genotyped using Illumina 2.5 Human Omni Beadchip. Candidate genes associated with A. lumbricoides responses were identified and SNVs in these selected genes associated with the Th2 immune response to A. lumbricoides. Haplotype, gene expression, and epigenetic analyses were done to identify potential associations with Th2 immune responses. GWAS on samples from 1,189 children identified WSB1 as a candidate gene, and IL-21R was selected as a biologically relevant linked gene for further analysis. Variants in WSB1 and IL21R were associated with markers of Th2 immune responses: increased A. lumbricoides-specific IgE and IL-5/IL-13 by PBLs from infected compared to uninfected individuals. In infected children, WSB1 but not IL21R gene expression was suppressed and increased methylation was observed in the WSB1 promoter region. This is the first study to show an association between genetic variants in WSB1 and IL21R and Th2 immune responses during A. lumbricoides infections in children. WSB1/IL21R pathways could provide a potential target for the treatment of Th2-mediated diseases.

A genetic variant in the promoter of CD46 is associated with the risk and prognosis of hepatocellular carcinoma

CD46 (also known as membrane cofactor protein), which is a member of the membrane-bound complement regulatory protein family, has been reported to cause cancer cells to escape complement-dependent cytotoxicity. However, the association between CD46 polymorphisms and the risk of hepatocellular carcinoma (HCC) has not been investigated. This two-stage association study was conducted to assess the relationship between the tagging single nucleotide polymorphisms (tagSNPs) of CD46 and HCC risk and prognosis. A series of functional analyses were performed to study the underlying mechanisms. Among the eight tagSNPs, rs2796267 (P = .003) and rs2796268 (P = .011) were found to modify HCC risk in the discovery set. Only rs2796267 (P < .0001) was confirmed to be associated with HCC susceptibility in the validation set. Compared with the wild-type AA genotype, the GG genotype significantly increased the HCC risk (adjusted odds ratio [OR] = 2.03; 95% confidence interval [CI], 1.34-3.08; P = .001). Moreover, subgroups analysis suggested a positive correlation among male and younger patients, especially among drinkers, smokers, and hepatitis B surface antigen-positive individuals. In functional analyses, we found that the rs2796267 G allele in the promoter region of CD46 could increase the expression of CD46 by affecting the binding affinity of STAT5a. Furthermore, Cox regression analysis revealed that the rs2796267 AG/GG genotype was significantly associated with worse prognosis of resected patients with HCC (hazard ratio = 2.27; 95% CI, 1.27-4.05; P = .006). These results suggest that the CD46 rs2796267 polymorphism may contribute to susceptibility and prognosis of HCC by altering promoter activity.

BRM: the core ATPase subunit of SWI/SNF chromatin-remodelling complex-a tumour suppressor or tumour-promoting factor?

BRM (BRAHMA) is a core, SWI2/SNF2-type ATPase subunit of SWI/SNF chromatin-remodelling complex (CRC) involved in various important regulatory processes including development. Mutations in SMARCA2, a BRM-encoding gene as well as overexpression or epigenetic silencing were found in various human diseases including cancer. Missense mutations in SMARCA2 gene were recently connected with occurrence of Nicolaides-Baraitser genetics syndrome. By contrast, SMARCA2 duplication rather than mutations is characteristic for Coffin-Siris syndrome. It is believed that BRM usually acts as a tumour suppressor or a tumour susceptibility gene. However, other studies provided evidence that BRM function may differ depending on the cancer type and the disease stage, where BRM may play a role in the disease progression. The existence of alternative splicing forms of SMARCA2 gene, leading to appearance of truncated functional, loss of function or gain-of-function forms of BRM protein suggest a far more complicated mode of BRM-containing SWI/SNF CRCs actions. Therefore, the summary of recent knowledge regarding BRM alteration in various types of cancer and highlighting of differences and commonalities between BRM and BRG1, another SWI2/SNF2 type ATPase, will lead to better understanding of SWI/SNF CRCs function in cancer development/progression. BRM has been recently proposed as an attractive target for various anticancer therapies including the use of small molecule inhibitors, synthetic lethality induction or proteolysis-targeting chimera (PROTAC). However, such attempts have some limitations and may lead to severe side effects given the homology of BRM ATPase domain to other ATPases, as well as due to the tissue-specific appearance of BRM- and BRG1-containing SWI/SNF CRC classes. Thus, a better insight into BRM-containing SWI/SNF CRCs function in human tissues and cancers is clearly required to provide a solid basis for establishment of new safe anticancer therapies.

Association of two BRM promoter polymorphisms and smoking status with malignant pleural mesothelioma risk and prognosis

Brahma (BRM), of the SWI/SNF complex, has two 6 to 7 bp insertion promoter polymorphisms (BRM-741/BRM-1321) that cause epigenetic BRM suppression, and are associated with risk of multiple cancers. BRM polymorphisms were genotyped in malignant pleural mesothelioma (MPM) cases and asbestos-exposed controls. Multivariable logistic regression (risk) and Cox regression (prognosis) were performed, including stratified analyses by smoking status to investigate the effect of polymorphisms on MPM risk and prognosis. Although there was no significant association overall between BRM-741/BRM-1321 and risk in patients with MPM, a differential effect by smoking status was observed (P-interaction < .001), where homozygous variants were protective (aOR of 0.18-0.28) in ever smokers, while never smokers had increased risk when carrying homozygous variants (aOR of 2.7-4.4). While there was no association between BRM polymorphisms and OS in ever-smokers, the aHR of carrying homozygous-variants of BRM-741, BRM-1321 or both were 4.0 to 8.6 in never-smokers when compared to wild-type carriers. Mechanistically, lower mRNA expression of BRM was associated with poorer general cancer prognosis. Electrophoretic mobility shift assays and chromatin immunoprecipitation experiments (ChIP) revealed high BRM insertion variant homology to MEF2 regulatory binding sites. ChIP experimentation confirmed MEF2 binding only occurs in the presence of insertion variants. DNA-affinity purification assays revealed YWHA scaffold proteins as vital to BRM mRNA expression. Never-smokers who carry BRM homozygous variants have an increased chance of developing MPM, which results in worse prognosis. In contrast, in ever-smokers, there may be a protective effect, with no difference in overall survival. Mechanisms for the interaction between BRM and smoking require further study.

Recurrent chromosomal and epigenetic alterations in oral squamous cell carcinoma and its putative premalignant condition oral lichen planus

Head and neck squamous cell carcinoma (HNSCC) affects about 700.000 individuals per year worldwide with oral squamous cell carcinoma (OSCC) as a major subcategory. Despite a comprehensive treatment concept including surgery, radiation, and chemotherapy the 5-year survival rate is still only about 50 percent. Chronic inflammation is one of the hallmarks of carcinogenesis. Until now, little is known about the premalignant status of oral lichen planus (OLP) and molecular alterations in OLP are still poorly characterized. Our study aims to delineate differential DNA methylation patterns in OLP, OSCC, and normal oral mucosa.

By applying a bead chip approach, we identified altered chromosomal patterns characteristic for OSCC while finding no recurrent alterations in OLP. In contrast, we identified numerous alterations in the DNA methylation pattern in OLP, as compared to normal controls, that were also present in OSCC. Our data support the hypothesis that OLP is a precursor lesion of OSCC sharing multiple epigenetic alterations with OSCC.

Brahma deficiency in keratinocytes promotes UV carcinogenesis by accelerating the escape from cell cycle arrest and the formation of DNA photolesions

BACKGROUND

Ultraviolet radiation (UVR) is the principal cause of keratinocyte skin cancers. Previous work found that levels of the chromatin remodelling protein, Brahma (Brm), are diminished during the progression from actinic keratoses to cutaneous squamous cell carcinomas in humans, and its loss in UV-irradiated mouse skin causes epidermal hyperplasia and increased tumour incidence.

METHODS

The skins of mice and mouse and human keratinocytes deficient in Brm were exposed to UVR and evaluated for cell cycle progression and DNA damage response.

OBJECTIVE

To identify the mechanisms by which loss of Brm contributes to UVR-induced skin carcinogenesis.

RESULTS

In both mouse keratinocytes and HaCaT cells, Brm deficiency led to an increased cell population growth following UVR exposure compared to cells with normal levels of Brm. Cell cycle analysis using a novel assay showed that Brm-deficient keratinocytes entered cell cycle arrest normally, but escaped from cell cycle arrest faster, enabling them to begin proliferating earlier. In mouse keratinocytes, Brm primarily affected accumulation in G₀/G₁-phase, whereas in HaCaT cells, which lack normal p53, accumulation in G₂/M-phase was affected. Brm-deficient keratinocytes in mouse skin and human cell cultures also had higher levels of UVR-induced cyclobutane pyrimidine dimer photolesions. These effects occurred without any compensatory increase in DNA repair or cell death to remove photolesions or the cells that harbor them from the keratinocyte population.

CONCLUSION

The loss of Brm in keratinocytes exposed to UVR enables them to resume proliferation while harboring DNA photolesions, leading to an increased fixation of mutations and, consequently, increased carcinogenesis.

Two functional indel polymorphisms in the promoter region of the Brahma gene (BRM) and disease risk and progression-free survival in colorectal cancer

Background and objective

The Brahma gene (BRM) encodes a catalytic ATPase subunit of the Switch/Sucrose non-fermentable (SWI/SNF) complex, which modulates gene expression and many important cellular processes. Two indel polymorphisms in the promoter region of BRM (BRM-741 and BRM-1321) are associated with its reduced expression and the risk of susceptibility or survival outcomes in multiple solid cancers. In this study, we have examined these variants in relation to susceptibility and survival outcomes in colorectal cancer.

Methods

Genotypes were obtained using TaqMan assays in 427 cases and 408 controls. Multivariate logistic and Cox regression models were fitted to examine the associations of the BRM-741 and BRM-1321 genotypes adjusting for relevant covariates. Sub-group analyses based on tumor location and patient sex were also performed. In all analyses, indels were examined individually as well as in combination.

Results

Our results showed that there was no association between the BRM polymorphisms and the risk of colorectal cancer. However, genotype combinations of the BRM-741 and BRM-1321 variants were associated with the risk of colon cancer. Particularly, patients having at least one variant allele had increased risk of colon cancer when compared to patients with the double wild-type genotype. In the survival analyses, BRM-741 heterozygosity was associated with longer progression-free survival time in the colorectal cancer patients. A stronger association was detected in the male patients under the recessive genetic model where the homozygosity for the variant allele of BRM-741 was associated with shorter progression-free survival time.

Conclusions

Our analyses suggest that BRM-741 and BRM-1321 indels are associated with the risk of developing colon cancer and the BRM-741 indel is associated with the disease progression in colorectal cancer patients, especially in the male patients. Although our results show a different relationship between these indels and colorectal cancer compared to other cancer sites, they also suggest that BRM and its promoter variants may have biological roles in susceptibility and survival outcomes in colorectal cancers. Performing further analyses in additional and larger cohorts are needed to confirm our conclusions.

The association of lncRNA-HULC polymorphisms with hepatocellular cancer risk and prognosis

BACKGROUND

Genetic polymorphisms in lncRNA HULC may affect the susceptibility and clinical outcome of cancer. We aimed to investigate the association of HULC tagSNPs with the risk and prognosis of hepatocellular cancer, as well as the influence of the SNPs on lncRNA expression level.

METHODS

A total of 1338 samples were recruited in the risk study. Among them, 351 HCC patients were involved in the prognosis study. SNP genotyping was performed using KASP method and lncRNA expression was detected by Real-time PCR.

RESULTS

We found a promoter SNP, rs1041279, was associated with a 1.41-fold increased HCC risk (P = 0.032). In the stratified analysis, rs1041279 had greater ORs for the increased HCC risk in the male subgroup (P = 0.014, OR = 1.54). Furthermore, multi-logistic regression analysis revealed a two-way interaction effect of smoking-rs2038540 SNP on HCC risk (OR = 4.20). And MDR analysis consistently demonstrated a SNP-environmental interaction among smoking-drinking-rs2038540 SNP as the best model for predicting HCC risk (P = 0.0107). In our study, no significant association was found between HULC SNPs and the overall survival (P > 0.05), and no significant effect was observed of rs1041279 SNP on lncRNA-HULC expression (P > 0.05).

CONCLUSION

lncRNA-HULC rs1041279 SNP and the interaction of rs2038540 SNP with environmental factors could enhance HCC risk.