The six-nucleotide deletion/insertion variant in the CASP8 promoter region is inversely associated with risk of squamous cell carcinoma of the head and neck

Circulating tumour DNA alterations: emerging biomarker in head and neck squamous cell carcinoma

Head and Neck cancers (HNC) are a heterogeneous group of upper aero-digestive tract cancer and account for 931,922 new cases and 467,125 deaths worldwide. About 90% of these cancers are of squamous cell origin (HNSCC). HNSCC is associated with excessive tobacco and alcohol consumption and infection with oncogenic viruses. Genotyping tumour tissue to guide clinical decision-making is becoming common practice in modern oncology, but in the management of patients with HNSCC, cytopathology or histopathology of tumour tissue remains the mainstream for diagnosis and treatment planning. Due to tumour heterogeneity and the lack of access to tumour due to its anatomical location, alternative methods to evaluate tumour activities are urgently needed. Liquid biopsy approaches can overcome issues such as tumour heterogeneity, which is associated with the analysis of small tissue biopsy. In addition, liquid biopsy offers repeat biopsy sampling, even for patients with tumours with access limitations. Liquid biopsy refers to biomarkers found in body fluids, traditionally blood, that can be sampled to provide clinically valuable information on both the patient and their underlying malignancy. To date, the majority of liquid biopsy research has focused on blood-based biomarkers, such as circulating tumour DNA (ctDNA), circulating tumour cells (CTCs), and circulating microRNA. In this review, we will focus on ctDNA as a biomarker in HNSCC because of its robustness, its presence in many body fluids, adaptability to existing clinical laboratory-based technology platforms, and ease of collection and transportation. We will discuss mechanisms of ctDNA release into circulation, technological advances in the analysis of ctDNA, ctDNA as a biomarker in HNSCC management, and some of the challenges associated with translating ctDNA into clinical and future perspectives. ctDNA provides a minimally invasive method for HNSCC prognosis and disease surveillance and will pave the way in the future for personalized medicine, thereby significantly improving outcomes and reducing healthcare costs.

From Apoptosis to Necroptosis: The Death Wishes to Cancer

DNA mutation is a common event in the human body, but in most situations, it is fixed right away by the DNA damage response program. In case the damage is too severe to repair, the programmed cell death system will be activated to get rid of the cell. However, if the damage affects some critical components of this system, the genetic scars are kept and multiply through mitosis, possibly leading to cancer someday. There are many forms of programmed cell death, but apoptosis and necroptosis represent the default and backup strategy, respectively, in the maintenance of optimal cell population as well as in cancer prevention. For the same reason, the ideal approach for cancer treatment is to induce apoptosis in the cancer cells because it proceeds 20 times faster than tumor cell proliferation and leaves no mess behind. Induction of necroptosis can be the second choice in case apoptosis becomes hard to achieve, however, necroptosis finishes the job at a cost-inflammation.

Synthesis of novel unnatural α-amino acids (UAAs) containing 7-hydroxy-2,2-dimethyl-chroman using isoxazole as a linker

An efficient and novel method for the preparation of unnatural α-amino acids (UAAs) containing 7-hydroxy-2,2-dimethyl-chroman via a 1,3-di-polar-cyloaddition reaction has been described.

A systematic review of genes affecting mitochondrial processes in cancer

Malignant conversion of cancer cells requires efficient mitochondria reprogramming orchestrated by hundreds of genes. The transformation includes increased energy demand, biosynthesis of precursors, and reactive oxygen species needed to accelerate cell growth, proliferation, and survival. Reprogramming involves complex gene alterations that have not been methodically curated. Therefore, we systematically analyzed the literature of cancer-related genes in mitochondria. Through the analysis of >2500 PubMed abstracts and >1600 human genes, we identified 228 genes showing clear roles in cancer. Each gene was classified according to their homeostatic function, together with the pathological transitions that contribute to specific cancer hallmarks. The potential clinical relevance of these hallmarks and genes is discussed by representative examples and validated by detecting differences in gene expression levels across 16 different types of cancer. A compendium, including the gene functions and alterations underpinning cancer progression, can be explored at http://bioinformatica.mty.itesm.mx/MitoCancer.

Association of CASP8 polymorphisms and cancer susceptibility: A meta-analysis

Caspase-8 plays is an essential enzyme in apoptosis pathway. Several investigation have been done to identify the relation between CASP8 polymorphisms and different human cancers, but, the findings are still debated. The aim of the current investigation is to assess if CASP8 rs3834129 (-652 6N insertion/deletion), rs1045485 G > C, rs3769818 G > A, rs6723097 A > C, rs3769821 T > C, rs13113 T > A, rs3769825 G > A, rs2293554 A > C, and rs10931936 C > T polymorphisms are linked to susceptibility of cancer. Our team has extracted the eligible studies up to July 4, 2019, from different sources. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were estimated to quantitatively evaluate the association between CASP8 polymorphisms and cancer susceptibility. Our results showed that the rs3834129 and rs1045485 polymorphisms meaningfully reduced the risk of cancer, while the rs3769818, rs3769821 and rs3769825 polymorphisms considerably increased cancer susceptibility. No association of rs6723097, rs13113, rs2293554 and rs10931936 polymorphisms was observed with cancer susceptibility. The CASP8 rs3834129 polymorphism reduced the risk of gastrointestinal, digestive tract, colorectal, breast and lung cancers. Furthermore, the cancer risk was decreased in Asian and Caucasian populations as well as population- and hospital-based studies due to this polymorphism. There was not any relation between this gene polymorphism and the risk of prostate and cervical cancer development. Regarding the CASP8 rs1045485 polymorphism, the reduced breast cancer risk along with the risk of cancer in Caucasians, population- and hospital-based studies were observed.

Combined Effect of HPV and Several Gene SNPs in Laryngeal Cancer

Background and objectives: Laryngeal squamous cell carcinoma (LSCC) is one of the most common head and neck tumors. The molecular mechanism of LSCC remains unclear. The aim of this study was to evaluate the prevalence of Human papillomavirus (HPV) and single nucleotide polymorphisms (SNPs) of TP53, MDM2, MDM4, MTHFR, CASP8, and CCR5 genes in LSCC, and to assess their correlations with patient survival. Materials and Methods: 49 LSCC patients were enrolled in this study. PCR and qRT-PCR were used to detect, identify, and quantify HPV. SNPs were genotyped using PCR and PCR-RFLP. Results: By analyzing the interactions of the SNPs of the genes with clinical parameters, the majority of patients with lymph node status (N1,2) were identified as carriers of MDM2T/G, CASP8ins/del, CCR5wt/wt SNP. Cluster analysis showed that patients with MDM2T/T SNP survive longer than patients identified as CASP8ins/ins, MTHFRC/C, and MDM4A/A variant carriers; meanwhile, LSCC patients with MDM2T/T polymorphic variant had the best survival. Multivariate analysis showed that HPV-positive patients without metastasis in regional lymph nodes (N0) and harboring CASP8ins/del variant had the best survival. Meanwhile, HPV-negative patients with identified metastasis in lymph nodes (N1 and N2) and CASP8ins/del variant had poor survival. Conclusions: This finding suggests patients survival prognosis and tumor behavior are different according HPV status, SNP variants, and clinical characteristics of the LSCC.

CASP8 (rs3834129) and CASP3 (rs4647601) polymorphisms in oropharynx cancer risk, tumor cell differentiation, and prognosis in a cohort of the Brazilian population

The objective of this research was to assess the association of genetic polymorphisms related to intrinsic apoptosis pathway CASP8 rs3834129 and CASP3 rs4647601 with the risk, clinical and pathological aspects, and survival of oropharynx squamous cell carcinoma (OPSCC) patients that received cisplatin and radiotherapy. The genotypes were identified in 198 patients with OPSCC and 200 controls using polymerase chain reaction methods. Chi square or Fisher's exact test and logistic regression were applied for the detection of differences between groups. Patients' genotypes were statistically evaluated considering the event-free survival and overall analysis using Kaplan-Meier estimate and Cox regression. CASP3 rs4647601 GG genotype (44.4% vs. 30.0%, p = 0.03) and G allele (63.9% vs. 55.5%, p = 0.04) were more common in patients with OPSCC than in controls. Carriers of GG genotype and G allele were under 1.78-fold and 1.40-fold increased risk of OPSCC than others, respectively. The frequency of CASP8 rs3834129 DD genotype was higher in patients with OPSCC with poorly differentiated or undifferentiated tumors when compared to others (34.5% vs. 16.1%, p = 0.02). No influence of CASP8 and CASP3 polymorphisms on OPSCC patients' survival was seen in this study. Our results indicate that inherited genetic variants in the intrinsic apoptosis pathway related to CASP3 rs4647601 and CASP8 rs3834129 polymorphisms may be an important determinant of OPSCC risk and tumor cell differentiation.

CASP8 -652 6N insertion/deletion polymorphism and overall cancer risk: evidence from 49 studies

The CASP8 -652 6N insertion/deletion (I/D) polymorphism reduces expression of caspase 8. We conducted a meta-analysis to clarify the relationship between this polymorphism and cancer risk. Eligible articles were retrieved from PubMed, EMBASE, CNKI, and WANFANG databases through February 2017. A total of 33 articles with 49 studies, including 33,494 cases and 36,397 controls, were analyzed. We found that the CASP8 -652 6N ins/del polymorphism was associated with decreased overall cancer risk in five genetic models [DD vs. II: odds ratio (OR)=0.76, 95% confidence interval (CI)=0.69–0.84, ID vs. II: OR=0.87, 95% CI=0.83–0.92, DD vs. ID/II: OR=0.82, 95% CI=0.75–0.89, ID/DD vs. II: OR=0.85, 95% CI=0.80–0.90, and D vs. I: OR=0.87, 95% CI=0.83–0.91]. Stratified analyses showed that the polymorphism was associated with decreased risk of colorectal, breast, esophageal, renal cell, lung, cervical, bladder, gastric, and other cancers. Overall cancer risk was reduced in Asian and Caucasian patients, both hospital- and population-based studies, and both high and low quality studies. Our results highlight the role of the CASP8 -652 6N ins/del polymorphism in decreasing cancer risk. Further studies with large-cohort populations, especially for specific cancer types and ethnic groups, are needed to confirm our findings.

Apoptotic capacity and risk of squamous cell carcinoma of the head and neck

BACKGROUND

Tobacco smoke and alcohol drinking are the major risk factors for squamous cell carcinoma of the head and neck (SCCHN). Smoking and drinking cause DNA damage leading to apoptosis, and insufficient apoptotic capacity may favour development of cancer because of the dysfunction of removing damaged cells. In the present study, we investigated the association between camptothecin (CPT)-induced apoptotic capacity and risk of SCCHN in a North American population.

METHODS

In a case-control study of 708 SCCHN patients and 685 matched cancer-free controls, we measured apoptotic capacity in cultured peripheral blood lymphocytes in response to in vitro exposure to CPT by using the flow cytometry-based method.

RESULTS

We found that the mean level of apoptotic capacity in the cases (45.9 ± 23.3%) was significantly lower than that in the controls (49.0 ± 23.1%) (P = 0.002). When we used the median level of apoptotic capacity in the controls as the cutoff value for calculating adjusted odds ratios, subjects with a reduced apoptotic capacity had an increased risk (adjusted odds ratio = 1.42, 95% confidence interval = 1.13-1.78, P = 0.002), especially for those who were age ≥57 (1.73, 1.25-2.38, 0.0009), men (1.76, 1.36-2.27, <0.0001) and ever drinkers (1.67, 1.27-2.21, 0.0003), and these variables significantly interacted with apoptotic capacity (P_interaction = 0.015, 0.005 and 0.009, respectively). A further fitted prediction model suggested that the inclusion of apoptotic capacity significantly improved in the prediction of SCCHN risk.

CONCLUSION

Individuals with a reduced CPT-induced apoptotic capacity may be at an increased risk of developing SCCHN, and apoptotic capacity may be a biomarker for susceptibility to SCCHN.

The dark matter of the cancer genome: aberrations in regulatory elements, untranslated regions, splice sites, non-coding RNA and synonymous mutations

Cancer is a disease of the genome caused by oncogene activation and tumor suppressor gene inhibition. Deep sequencing studies including large consortia such as TCGA and ICGC identified numerous tumor‐specific mutations not only in protein‐coding sequences but also in non‐coding sequences. Although 98% of the genome is not translated into proteins, most studies have neglected the information hidden in this “dark matter” of the genome. Malignancy‐driving mutations can occur in all genetic elements outside the coding region, namely in enhancer, silencer, insulator, and promoter as well as in 5′‐UTR and 3′‐UTR. Intron or splice site mutations can alter the splicing pattern. Moreover, cancer genomes contain mutations within non‐coding RNA, such as microRNA, lncRNA, and lincRNA. A synonymous mutation changes the coding region in the DNA and RNA but not the protein sequence. Importantly, oncogenes such as TERT or miR‐21 as well as tumor suppressor genes such as TP53/p53,APC,BRCA1, or RB1 can be affected by these alterations. In summary, coding‐independent mutations can affect gene regulation from transcription, splicing, mRNA stability to translation, and hence, this largely neglected area needs functional studies to elucidate the mechanisms underlying tumorigenesis. This review will focus on the important role and novel mechanisms of these non‐coding or allegedly silent mutations in tumorigenesis.

Reduced DNA double-strand break repair capacity and risk of squamous cell carcinoma of the head and neck--A case-control study

Tobacco smoke and alcohol use play important roles in the etiology of squamous cell carcinoma of the head and neck (SCCHN). Smoking causes DNA damage, including double-strand DNA breaks (DSBs), that leads to carcinogenesis. To test the hypothesis that suboptimal DSB repair capacity is associated with risk of SCCHN, we applied a flow cytometry-based method to detect the DSB repair phenotype first in four EBV-immortalized human lymphoblastoid cell lines and then in human peripheral blood T-lymphocytes (PBTLs). With this blood-based laboratory assay, we conducted a pilot case-control study of 100 patients with newly diagnosed, previously untreated SCCHN and 124 cancer-free controls of non-Hispanic whites. We found that the mean DSB repair capacity level was significantly lower in cases (42.1%) than that in controls (54.4%) (P<0.001). When we used the median DSB repair capacity level in the controls as the cutoff value for calculating the odds ratios (ORs) with adjustment for age, sex, smoking and drinking status, the cases were more likely than the controls to have a reduced DSB repair capacity (adjusted OR=1.93; 95% confidence interval, CI=1.04-3.56, P=0.037), especially for those subjects who were ever drinkers (adjusted OR=2.73; 95% CI=1.17-6.35, P=0.020) and had oropharyngeal tumors (adjusted OR=2.17; 95% CI=1.06-4.45, P=0.035). In conclusion, these findings suggest that individuals with a reduced DSB repair capacity may be at an increased risk of developing SCCHN. Larger studies are warranted to confirm these preliminary findings.

Molecular Cell Biology of Apoptosis and Necroptosis in Cancer

Cell death is a major mechanism to eliminate cells in which DNA is damaged, organelles are stressed, or oncogenes are overexpressed, all events that would otherwise predispose cells to oncogenic transformation. The pathways that initiate and execute cell death are complex, genetically encoded, and subject to significant regulation. Consequently, while these pathways are often mutated in malignancy, there is considerable interest in inducing cell death in tumor cells as therapy. This chapter addresses our current understanding of molecular mechanisms contributing to two cell death pathways, apoptotic cell death and necroptosis, a regulated form of necrotic cell death. Apoptosis can be induced by a wide variety of signals, leading to protease activation that dismantles the cell. We discuss the physiological importance of each apoptosis pathway and summarize their known roles in cancer suppression and the current efforts at targeting each pathway therapeutically. The intricate mechanistic link between death receptor-mediated apoptosis and necroptosis is described, as well as the potential opportunities for utilizing necroptosis in the treatment of malignancy.

Caspase-8 polymorphisms and risk of oral squamous cell carcinoma

Caspase-8 (CASP8) is a key controller of apoptosis, and its deregulation is crucially involved in carcinogenesis. The aim of the present study was to evaluate the function of CASP8 polymorphisms in oral squamous carcinoma (OSCC) by evaluating the risk associated with three single-nucleotide polymorphisms (SNPs) in a case-control study in a Han Chinese patient population. A total of 505 individuals with clinically diagnosed OSCC and 507 healthy controls were tested for the three SNPs rs3834129, rs13016963 and rs1045485, using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing analysis. After adjusting for other confounders, the genotype frequencies of CASP8 -652 6N ins/del promoter polymorphism (rs3834129) were found to be lower in patients with OSCC compared with normal subjects. No significant difference was detected in the genotype frequencies of rs13016963 between the patients and control subjects. However, the AA genotype frequency of rs1306963 was associated with OSCC as a risk factor among non-smokers and non-drinkers. For CASP8, rs1045485 was not present in any of the patients with OSCC or control subjects. These results suggest that the del allele of rs3834129 may play a protective role in the tumorigenesis of OSCC and may be useful as a genetic susceptibility marker for OSCC in the population studied.

Identification of a secondary promoter of CASP8 and its related transcription factor PURα

Caspase-8 (CASP8) is an essential initiator of apoptosis and is associated with many diseases in humans including esophageal squamous cell carcinoma. CASP8 produces a variety of transcripts, which might perform distinct functions. However, the cis and trans transcriptional determinants that control CASP8 expression remain poorly defined. Using a series of luciferase reporter assays, we identified a novel secondary promoter of CASP8 within chr2: 202,122,236 to 202,123,227 and 25 kb downstream of the previously described CASP8 promoter. ENCODE ChIP-seq data for this novel promoter region revealed several epigenetic features, including high levels of histone H3 lysine 27 acetylation and lysine 4 methylation, as well as low levels of CpG island methylation. We developed a mass spectrometry based strategy to identify transcription factors that contribute to the function of the secondary promoter. We found that the transcription activator protein PURα is specifically involved in the transcriptional activation of the secondary promoter and may exert its function by forming a complex with E2F-1 and RNA polymerase II. PURα can bind to both DNA and RNA, and functions in the initiation of DNA replication, regulation of transcription. We observed that knockdown of PURα expression decreased the transcriptional activity of the secondary promoter and mRNA expression of CASP8 isoform G. Although the physiologic roles of this secondary promoter remain unclear, our data may help explain the complexity of CASP8 transcription and suggest that the various caspase 8 isoforms may have distinct regulations and functions.

Genomic aberrations in the HTPAP promoter affect tumor metastasis and clinical prognosis of hepatocellular carcinoma

We previously reported that the intronic tagSNP +357G/C in the metastasis suppressor HTPAP is associated with metastasis and prognosis of hepatocellular carcinoma (HCC). The aim of this study was to investigate whether SNPs in the HTPAP promoter modulate HTPAP expression and prognosis of HCC. Genomic DNA from 572 microdissected HCCs were genotyped by pyrosequencing and verified by direct sequencing. Haplotype blocks were analyzed. Reporter plasmids were constructed and transfected into HCC cell lines. Transcriptional activities of plasmids were analyzed by dual-luciferase reporter systems. HTPAP expression was measured by real-time quantitative PCR, western blots, and tissue microarrays. Invasion was assessed by Matrigel assays. The prognostic values of HTPAP promoter SNPs in HCC were evaluated by Kaplan-Meier and Cox regression analyses. We identified six SNPs, including -1053A/G and +64G/C, in the HTPAP promoter. The SNPs were in complete linkage disequilibrium, resulting in three promoter haplotypes (promoter I:-1053AA/+64GG, promoter II: -1053AG/+64GC, and promoter III: -1053GG/+64CC). Promoter I manifested the highest luciferase index (p<0.005). However, no significant difference was observed between promoters II and III. We consistently found that HTPAP mRNA and protein levels were significantly higher in promoter I than that of promoter II+III (p<0.001). Invasion was increased in HCC cells transfected with promoters II+III compared to those transfected with promoter I (p<0.05). The HTPAP promoter II+III haplotype was associated with significantly increased metastasis compared to that of promoter I (p = 0.023). The postoperative five-year overall survival of patients with promoters II+III was lower than that of patients with promoter I (p = 0.006). Multivariate analysis showed that the promoter II+III haplotype was an adverse prognostic marker in HCC. The genetic variants at loci –1053 and +64 of the HTPAP promoter affect the expression of HTPAP, which might be a novel determinant and target for HCC prognosis.

A functional variant at the miR-885-5p binding site of CASP3 confers risk of both index and second primary malignancies in patients with head and neck cancer

Caspases are important regulators and executioners in the apoptosis pathways and play crucial roles in carcinogenesis. We tested the hypothesis that functional variants of CASP genes are associated with risk of squamous cell carcinoma of the head and neck (SCCHN) and second primary malignancy (SPM). We genotyped 7 selected, potentially functional single nucleotide polymorphisms (SNPs) located in the microRNA binding sites of the 3' untranslational region (UTR; 2 in CASP3, 1 in CASP6, and 4 in CASP7) and evaluated their associations first with risk of SCCHN in 1066 patients with SCCHN and 1074 cancer-free control subjects and then with SPM in 846 patients in the same non-Hispanic white study population. We found that compared with the CASP3 TT genotype of rs1049253, the variant TC/CC genotypes were associated with significantly increased risk of SCCHN (adjusted odds ratio=1.29 and 95% confidence interval=1.07-1.56) and SPM (adjusted hazard ratio=1.79 and 95% CI=1.02-3.16) and worse SPM-free survival (log-rank P = 0.020), but no associations were found for the other 6 SNPs. We then performed additional experiments to seek functional relevance of the rs1049253 SNP. First, the luciferase activity and miR-885-5p mimic transfection tests suggested that CASP3 was the target of miR-885-5p and that rs1049253T>C resulted in altered regulation of the CASP3 expression. Second, the rs1049253 CC genotype was associated with reduced levels of CASP3 mRNA in peripheral blood mononuclear cells from 118 SCCHN patients and 103 cancer-free control subjects and lower levels of CASP3 protein expression in 11 head and neck cancer cell lines, compared with the TT genotype. Taken together, our data suggest that the miR-885-5p binding site rs1049253T>C SNP in the 3'-UTR of CASP3 modulates CASP3 expression at both mRNA and protein levels and thus contributes to SCCHN susceptibility.

CASP-8 -652 6N ins/del polymorphism and cancer risk: A literature-based systematic HuGE review and meta-analysis

Caspase-8 (encoded by the CASP-8 gene) is crucial in generating cell death signals and eliminating potentially malignant cells. Genetic variation in CASP8 may affect susceptibility to cancer. The CASP-8 −652 6N ins/del (rs3834129) polymorphism has been previously reported to influence the progression to several cancers. However, the overall reported studies have shown inconsistent conclusions. In this human genome epidemiology (HuGE) review and meta-analysis, the aim was to identify the association between CASP-8 −652 6N ins/del polymorphism and cancer risk. According to the inclusion criteria, 19 case-control studies with a total of 23,172 cancer cases and 26,532 healthy controls were retrieved. Meta-analysis results showed that the del allele, del allele carrier and ins/del genotype of −652 6N ins/del in the CASP-8 gene were negatively associated with cancer risk (OR=0.91, 95% CI=0.84–0.98, P=0.01; OR=0.88, 95% CI=0.80–0.96, P=0.005; OR=0.91, 95% CI=0.85–0.98, P<0.001; respectively, while no significant correlation was observed between the del/del genotype of −652 6N ins/del and cancer risk (OR=0.89, 95% CI=0.79–1.01, P=0.08). In the subgroup analysis by ethnicity, the meta-analysis indicated that Caucasian populations harboring the del allele, del allele carriers and ins/del genotype had a lower cancer risk (OR=0.96, 95% CI=0.93–1.00, P=0.05; OR=0.86, 95% CI=0.75–1.00, P=0.05; OR=0.91, 95% CI=0.84–0.98, P=0.01; respectively). In addition, a negative association was found between the del allele of −652 6N ins/del in the CASP-8 gene and cancer risk in the Asian population (OR=0.89, 95% CI=0.83–0.97, P=0.005). In conclusion, this meta-analysis suggests that the del allele, del allele carrier and ins/del geno-type of the −652 6N ins/del polymorphism in the CASP-8 gene may be protective factors for cancer risk.

Bi-directional PCR allele-specific amplification (bi-PASA) for detection of caspase-8 -652 6N ins/del promoter polymorphism (rs3834129) in breast cancer

Caspase-8 (CASP8) plays a critical role in regulating apoptosis, and its functional polymorphisms may modify cancer risk. We investigated the possible association between CASP8 -652 6N ins/del (rs3834129) and the risk of breast cancer in a sample of Iranian population. This case-control study was done on 236 breast cancer patients and 203 cancer free healthy female. We designed a rapid and simple bi-directional PCR allele-specific amplification (bi-PASA) for detection of CASP8 -652 6N ins/del polymorphism. The results showed that the CASP8 -652 6N del/dl genotype was inversely associated with breast cancer risk (OR=0.33, 95% CI=0.17-0.65, p=0.001). The frequencies of the del allele in cases and controls were 29.1% and 38.6%, respectively. An inverse association between CASP8 6N del variant and the risk of breast cancer (OR=0.66, 95% CI=0.66-0.87, p=0.002) was found. In conclusion, the result suggests that the CASP8 -652 6N del polymorphism plays a protective role in susceptibility to breast cancer in our population. Further studies in other populations with larger samples are needed to confirm these findings.

Genotypic variants at 2q33 and risk of esophageal squamous cell carcinoma in China: a meta-analysis of genome-wide association studies

Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P< 5 × 10(-8), and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19-1.40) and P= 7.63 × 10(-10). An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.

Fine-mapping CASP8 risk variants in breast cancer

BACKGROUND

Multiple genome-wide and candidate gene association studies have been conducted in search of common risk variants for breast cancer. Recent large meta analyses, consolidating evidence from these studies, have been consistent in highlighting the caspase-8 (CASP8) gene as important in this regard. To define a risk haplotype and map the CASP8 gene region with respect to underlying susceptibility variant/s, we screened four genes in the CASP8 region on 2q33-q34 for breast cancer risk.

METHODS

Two independent data sets from the United Kingdom and the United States, including 3,888 breast cancer cases and controls, were genotyped for 45 tagging single nucleotide polymorphisms (tSNP) in the expanded CASP8 region. SNP and haplotype association tests were carried out using Monte Carlo-based methods.

RESULTS

We identified a three-SNP haplotype across rs3834129, rs6723097, and rs3817578 that was significantly associated with breast cancer (P < 5 × 10(-6)), with a dominant risk ratio and 95% CI of 1.28 (1.21-1.35) and frequency of 0.29 in controls. Evidence for this risk haplotype was extremely consistent across the two study sites and also consistent with previous data.

CONCLUSION

This three-SNP risk haplotype represents the best characterization so far of the chromosome upon which the susceptibility variant resides.

IMPACT

Characterization of the risk haplotype provides a strong foundation for resequencing efforts to identify the underlying risk variant, which may prove useful for individual-level risk prediction, and provide novel insights into breast carcinogenesis.

A functional variant at the miR-184 binding site in TNFAIP2 and risk of squamous cell carcinoma of the head and neck

Although the role of TNFAIP2 is still unclear, it is an important gene involved in apoptosis, and there are single-nucleotide polymorphisms (SNPs) at its microRNA (miRNA)-binding sites that could modulate miRNA target gene function. In this study, we evaluated associations of four selected SNPs (rs8126 T > C, rs710100 G > A, rs1052912 G > A and rs1052823 G > T) in the miRNA-binding sites of the 3' untranslated region (UTR) with squamous cell carcinoma of the head and neck (SCCHN) risk in 1077 patients with SCCHN and 1073 cancer-free controls in a non-Hispanic White population. We found that, compared with the rs8126 TT genotype, the variant C allele were associated with increased SCCHN risk in an allele dose-response manner (adjusted odds ratio = 1.48 and 95% confidence interval = 1.06-2.05 for CC, respectively; P(trend) = 0.009). No significant associations were seen for the other three SNPs (rs710100 G > A, rs1052912 G > A and rs1052823 G > T). Additionally, we identified that the rs8126 T > C SNP is within the miR-184 seed binding region in the 3' UTR of TNFAIP2. Further functional analyses showed that the rs8126 variant C allele led to significantly lower luciferase activity, compared with the T allele. In the genotype-phenotype correlation analysis of peripheral blood mononuclear cells from 64 SCCHN patients, the rs8126 CC genotype was associated with reduced expression of TNFAIP2 messenger RNA. Taken together, these findings indicate that the miR-184 binding site SNP (rs8126 T > C) in the 3' UTR of TNFAIP2 is functional by modulating TNFAIP2 expression and contributes to SCCHN susceptibility. Larger replication studies are needed to confirm our findings.

CASP8 -652 6N del and CASP8 IVS12-19G>A gene polymorphisms and susceptibility/prognosis of ESCC: a case control study in northern Indian population

BACKGROUND

Caspase8 influences carcinogenesis through regulation of apoptosis, hyperproliferation, and metastasis. Role of genetic variations in caspase8 has been explored in various cancers; however, their predictive and prognostic role in esophageal cancer is poorly understood.

METHODS

We investigated the association of two potential caspase8 polymorphisms: CASP8 -652 6N del and CASP8 IVS12-19 G>A polymorphisms with susceptibility and survival of 259 esophageal squamous cell carcinoma (ESCC) cases and 259 cancer-free controls from northern Indian population using PCR/PCR RFLP method.

RESULTS

CASP8 IVS12-19 AA genotype was found to be associated with significant increased risk of ESCC (odds ratio (OR) 3.28, 95% confidence interval (CI) 1.04-10.29) specifically in male subjects (OR 3.71, 95% CI 1.01-13.35) with lower third tumor anatomical location (OR 6.00, 95% CI 1.60-22.55). Kaplan-Meier and Cox Regression analysis showed lower median survival (7.13 months vs. 25.21 months) and greater hazard of death (HR 3.40, 95% CI 1.38-7.90) with CASP8 IVS12-19 AA genotype in ESCC cases compared to IVS12-19 GG genotype. However, no association of CASP8 -652 6N del polymorphism with susceptibility and prognosis of ESCC was observed.

CONCLUSION

CASP8 IVS12-19 G>A but not CASP8 -652 6N del polymorphism may modulate risk of ESCC and its survival outcome in northern Indian population.

CASP8 polymorphisms contribute to cancer susceptibility: evidence from a meta-analysis of 23 publications with 55 individual studies

Several potentially functional polymorphisms of CASP8 encoding an apoptotic enzyme, caspase 8, have been implicated in cancer risk, but individually published studies showed inconclusive results. We performed a meta-analysis of 23 publications with a total of 55 174 cancer cases and 59 336 controls from 55 individual studies. We summarized the data on the associations between three studied CASP8 polymorphisms (G>C D302H, -652 6N del and Ex14-271A>T) and cancer risk and performed subgroup analysis by ethnicity, cancer type, study design and etiology. We found that D302H CC and CG variant genotypes were associated with significantly reduced overall risk of cancers using conservative random genetic models [homozygote comparison: odds ratios (OR) = 0.79; 95% confidence interval (CI): 0.69-0.92; dominant comparison: OR = 0.93, 95% CI: 0.89-0.98; recessive comparison: OR = 0.81, 95% CI: 0.71-0.93). In further stratified analyses, the reduced cancer risk remained for subgroups of Caucasians, breast or estrogen-related cancers, and hospital- or population-based studies, except for an elevated risk for brain tumors. Similarly, the -652 6N del polymorphism was also associated with significantly reduced overall risk of cancers (homozygote comparison: OR = 0.84, 95% CI: 0.75-0.94; dominant comparison: OR = 0.88, 95% CI: 0.81-0.96; recessive comparison: OR = 0.90, 95% CI: 0.82-0.99) and all subgroups analyzed. However, the Ex14-271A>T polymorphism did not appear to have an effect on cancer risk. These results suggest that CASP8 D302H and -652 6N del polymorphisms are potential biomarkers for cancer risk.