ABSTRACT
Common genetic variation at human 14q22.2 tagged by rs4444235 is significantly associated with colorectal cancer (CRC) risk. Re-sequencing was used to comprehensively annotate the 17kb region of strong linkage disequilibrium encompassing rs4444235. Through bioinformatic analyses using H3K4Me1, H3K4Me3, and DNase-I hypersensitivity chromatin signatures and evolutionary conservation we identified seven candidate disease-causing single-nucleotide polymorphisms mapping to six regions within the 17-kb region predicted to have regulatory potential. Reporter gene studies of these regions demonstrated that the element to which rs4444235 maps acts as an allele-specific transcriptional enhancer. Allele-specific expression studies in CRC cell lines heterozygous for rs4444235 showed significantly increased expression of bone morphogenetic protein-4 (BMP4) associated with the risk allele (P<0.001). These data provide evidence for a functional basis for the non-coding risk variant rs4444235 at 14q22.2 and emphasizes the importance of genetic variation in the BMP pathway genes as determinants of CRC risk.
Subject(s)
Bone Morphogenetic Protein 4/genetics , Chromosomes, Human, Pair 14 , Colorectal Neoplasms/genetics , Polymorphism, Single Nucleotide , Alleles , Colorectal Neoplasms/etiology , Genotype , Humans , Linkage DisequilibriumABSTRACT
BACKGROUND: Exposure to ionising radiation is a well-established risk factor for multiple types of tumours, including malignant brain tumours. In the 1950s, radiotherapy was used to treat Tinea Capitis (TC) in thousands of children, mostly of North-African and Middle Eastern origin, during the mass migration to Israel. The over-representation of radiation-associated meningioma (RAM) and other cancers in specific families provide support for inherited genetic susceptibility to radiation-induced cancer. METHODS: To test this hypothesis, we genotyped 15 families segregating RAM using high-density single-nucleotide polymorphism (SNP) arrays. Using the family-based association test (FBAT) programme, we tested each polymorphism and haplotype for an association with RAM. RESULTS: The strongest haplotype associations were attained at 18q21.1 (P=7.5 × 10(-5)), 18q21.31 (P=2.8 × 10(-5)) and 10q21.3 (P=1.6 × 10(-4)). Although associations were not formally statistically significant after adjustment for multiple testing, the 18q21.1 and 10q21.3 associations provide support for a variation in PIAS2, KATNAL2, TCEB3C, TCEB3CL and CTNNA3 genes as risk factors for RAM. CONCLUSION: These findings suggest that any underlying genetic susceptibility to RAM is likely to be mediated through the co-inheritance of multiple risk alleles rather than a single major gene locus determining radiosensitivity.
Subject(s)
Genetic Predisposition to Disease , Genome-Wide Association Study/methods , Meningeal Neoplasms/genetics , Meningioma/genetics , Neoplasms, Radiation-Induced/genetics , Polymorphism, Single Nucleotide , Adult , Aged , Case-Control Studies , Chromosome Mapping , Family , Humans , Linkage Disequilibrium , Meningeal Neoplasms/etiology , Meningioma/etiology , Middle Aged , Neoplasms, Second Primary/etiology , Neoplasms, Second Primary/genetics , Radiation, Ionizing , Radiotherapy/adverse effectsABSTRACT
The synergistic interaction between various hemi/cellulolytic enzymes has become more important in order to achieve effective and optimal degradation of complex lignocellulose substrates for biofuel production. This study investigated the synergistic effect of three enzymes endoglucanase (EngE), mannanase (ManA) and xylanase (XynA) on the degradation of corn stalk, grass, and pineapple fruit pulp and determined the optimal degree of synergy between combinations of these enzymes. It was established that EngE was essential for degradation of all of the substrates, while the hemicellulases were able to contribute in a synergistic fashion to increase the activity on these substrates. Maximum specific activity and degree of synergy on the corn stalk and grass was found with EngE:XynA in a ratio of 75:25%, with a specific activity of 41.1 U/mg protein and a degree of synergy of 6.3 for corn stalk, and 44.1 U/mg protein and 3.4 for grass, respectively. The pineapple fruit pulp was optimally digested using a ManA:EngE combination in a 50:50% ratio; the specific activity and degree of synergy achieved were 52.4 U/mg protein and 2.7, respectively. This study highlights the importance of hemicellulases for the synergistic degradation of complex lignocellulose. The inclusion of a mannanase in an enzyme consortium for biomass degradation should be examined further as this study suggests that it may play an important, although mostly overlooked, role in the synergistic saccharification of lignocellulose.