Pathway analysis of genome-wide association study and transcriptome data highlights new biological pathways in colorectal cancer Abstract Colorectal cancer (CRC) is a common malignancy that meets the definition of a complex disease. Genome-wide association study (GWAS) has identified several loci of weak predictive value in CRC, however these do not fully explain the occurrence risk. Recently, gene set analysis has allowed enhanced interpretation of GWAS data in CRC, identifying a number of metabolic pathways as important for disease pathogenesis. Whether there are other important pathways involved in CRC, however, remains unclear. We present a systems analysis of KEGG pathways in CRC using (1) a human CRC GWAS dataset and (2) a human whole transcriptome CRC case-control expression dataset. Analysis of the GWAS dataset revealed significantly enriched KEGG pathways related to metabolism, immune system and diseases, cellular processes, environmental information processing, genetic information processing, and neurodegenerative diseases. Altered gene expression was confirmed in these pathways using the transcriptome dataset. Taken together, these findings not only confirm previous work in this area, but also highlight new biological pathways whose deregulation is critical for CRC. These results contribute to our understanding of disease-causing mechanisms and will prove useful for future genetic and functional studies in CRC. Keywords: colorectal cancer, GWAS, pathway analysis, transcriptome, metabolic pathways 1 Introduction Colorectal cancer (CRC), also called colon cancer or large bowel cancer, is the third most common form of cancer and the second leading cause of cancer-related death in the Western world with a lifetime risk in the United States of approximately 7%. CRC can be considered a complex disease, with a combination of genetic variants and environmental factors contributing to the illness as a whole (1). Relevant genetic variants have not been completely defined, however, genome-wide association study (GWAS) has recently revealed several novel CRC susceptibility loci (http://www.genome.gov/gwastudies/). The newly identified variants exert only very small risk effects and cannot fully explain the underlying CRC genetic risk. A large proportion of the heritability of CRC is therefore yet to be explained. To overcome one of the well-documented limitations of GWAS (2-3), namely its tendency to find large numbers of relatively weak predictors, investigators have developed a means of analyzing GWAS data that aggregates information over sets of related genes, such as genes in common pathways, to identify gene sets that are enriched for variants associated with disease. This “gene set” analysis strategy has yielded important new insights into the genetic mechanisms of many complex diseases (4), such as Alzheimer’s disease (5,6), rheumatoid arthritis (7,8), Crohn’s disease, celiac disease, type 1 diabetes, multiple sclerosis (9–12), schizophrenia (13,14), bipolar disorder (13), and cancers of the bladder (15), breast (16) and lung (17). In an attempt to further enhance the power of gene set analysis in situations in which there are a large number of predictors compared with sample size, Chen et al. developed an algorithm termed ‘gene set ridge regression in association studies (GRASS). When the GRASS algorithm was validated on CRC GWAS data, the top two enriched pathways were nicotinate and nicotinamide metabolism and transforming growth factor beta (TGF-beta) 2 signaling (Kyoto Encyclopedia of Genes and Genomes identifiers hsa00760 and hsa04350, respectively) (18). Several other pathways related to metabolism were also found to be enriched including glycosphingolipid biosynthesis – lacto and neolacto series (hsa00601), beta-Alanine metabolism (hsa00410), phenylalanine metabolism (hsa00360) and inositol phosphate metabolism (hsa00562) (18). In addition to GRASS, analysis of the CRC GWAS data using the existing gene set method proposed by Wang et al. (3) revealed a further 15 significant pathways, of which 14 were related to metabolism (18). To date, therefore, evidence from pathway analysis of CRC GWAS data has predominantly implicated the involvement of altered metabolic pathways in CRC occurrence. To better investigate whether there are other important pathways involved in CRC, we conducted a systems analysis of KEGG pathways, using (1) a CRC GWAS dataset and (2) a human whole genome CRC case-control gene expression dataset. Materials and methods CRC GWAS dataset The data were obtained from the Colorectal Tumour Gene Identification (CoRGI) consortium (19). This study included 922 cases and 927 controls. The CRC cases had at least one first-degree relative affected by CRC and one or more of the following phenotypes: CRC at age 75 or below; any colorectal adenoma at age 45 or below; three or more colorectal adenomas at age 75 or below; or a large or aggressive adenoma at age 75 or below. Controls were spouses or partners unaffected by cancer and without a personal family history of colorectal neoplasia. All cases and controls were of European ancestry and from the UK. A total of 555,352 SNPs were genotyped using the Illumina Hap550 BeadChip Array. On analysis, satisfactory data was obtained from 550,163 SNPs (99.1%), with mean individual sample call rates of 99.7 and 99.8% in cases and controls, 3 respectively. Of the SNPs satisfactorily genotyped, 2516 were monomorphic, leaving 547,647 SNPs for which genotype data were informative. After quality control, we used the summary genotype data from autosome 1-22, which included 534,050 SNPs. The Chi-square test (2 × 2 allele) was used to investigate the association between each polymorphism and CRC. All the chi-square tests were conducted using the R software environment (http://www.r-project.org/). Human CRC whole genome expression dataset The expression dataset was originally analyzed by Lascorz et al. (20). They collected 23 CRC gene expression profiling studies and performed a meta-analysis. In the 23 independent GEP datasets, 1897 different gene identifiers were reported to be differentially expressed (p < 0.05). The authors describe 1475 uniquely mapped genes including 603 up-regulated and 794 down-regulated genes from the original study. We used IDconverter software to convert the gene symbols to Entrez gene IDs (21). In the end, we selected 575 up-regulated genes and 763 down-regulated genes with unique Entrez gene IDs for our subsequent analysis. Gene-based GWAS data analysis ProxyGeneLD software was used to perform a gene-based test (22). This software is designed to flexibly consider the complex linkage disequilibrium (LD) patterns of the human genome and correct for the inflation of significance caused by gene length. The program uses the LD structures in the HapMap genotyping data (CEU samples of HapMap phase II, release 22). If a group of markers are in high LD in HapMap (r 2 > 0.8), they are tied to a “proxy cluster” and taken as a single signal. Next, each marker in the AD GWAS with statistically significant evidence of association is evaluated to determine (a) whether it 4 belongs to any proxy cluster and (b) whether the marker itself or any marker in the cluster is located in a genetic region. If a marker or cluster overlaps with a region extending across a gene, it is assigned as a signal showing the possible association of that gene. Finally, a p-value was assigned for each gene (22). Genes with p < 0.05 were considered to be significant. Gene set (pathway) analysis The WebGestalt toolkit (http://bioinfo.vanderbilt.edu/webgestalt/) was used to perform a pathway analysis (23). For a given KEGG pathway, a hypergeometric test was used to detect an overrepresentation of the CRC-related genes among all the genes in the pathway (23). The p-value of observing more than K CRC-related genes in the pathway was calculated by S N S ( )( ) K i mi P 1 , N i 0 ( ) m where N is the total number of genes that are of interest, S is the number of all CRC-related genes, m is the number of genes in the pathway, and K is the number of CRC-related genes in the pathway. The Benjamini & Hochberg (BH) method was used to correct for multiple testing. Pathways with adjusted p < 0.05 was considered to be significant. To reduce the multiple-testing issue, and to avoid testing overly narrow or broad pathways, we selected pathways that contained at least 20 and at most 300 genes for subsequent analysis. Results Pathway analysis of the CRC GWAS dataset Using ProxyGeneLD, we identified 981 CRC genes with p < 0.05. Pathway analysis was 5 conducted of all 981 significant genes. We identified 34 significant KEGG pathways (adjusted p < 0.05) that each included at least five CRC genes identified in the gene-based method (Table 1). According to the KEGG classifications, the functions of these pathways included metabolism (n = 8), cellular processes (n = 5), environmental information processing (n = 5), genetic information processing (n = 5), neurodegenerative diseases (n = 3) and the immune system (n = 2). The eight metabolic pathways in which genes showed significant enrichment included oxidative phosphorylation, glycerophospholipid metabolism, fructose and mannose metabolism, purine metabolism, amino sugar and nucleotide sugar metabolism, arginine and proline metabolism, arachidonic acid metabolism and retinol metabolism. Detailed information is described in supplementary Table 1. Table 1 Pathway analysis of the human CRC whole genome expression dataset For the expression dataset, to achieve internal comparison, we analyzed the significantly up-regulated and down-regulated genes (CRC cases vs controls) separately. Using the up-regulated genes, we identified 92 significant KEGG pathways (adjusted p < 0.05) that each included at least five CRC genes. These pathways were mainly related to immune system and diseases (n = 18), environmental information processing (n = 12), infectious diseases (n = 11), cellular processes (n = 10), cancers (n = 9), metabolism (n = 5) and cardiovascular diseases (n = 4). Importantly, we observed an enrichment of significantly up-regulated genes in 25 of 34 significant KEGG pathways identified by analysis of the GWAS data (Table 2). These results are provided in detail in supplementary Table 2. 6 Using the down-regulated genes, we identified 105 significant KEGG pathways (adjusted p < 0.05) that included at least five CRC genes. These pathways were mainly related to metabolism (n = 15), immune system and diseases (n = 13), cancers (n = 13), cellular processes (n = 12), environmental information processing (n = 11), genetic information processing (n = 10) infectious diseases (n = 9), neurodegenerative diseases (n = 5), and cardiovascular diseases (n = 4). As with the over-expressed genes, we observed an enrichment of significantly down-regulated genes in the majority of the significant KEGG pathways identified by the GWAS analysis (27 of 34; Table 3). Detailed results are provided in supplementary Table 3. Table 2 Discussion CRC is a complex disease that is likely to caused by a combination of genetic and environmental factors. Recently, Chen et al. applied two pathway analysis methods to CRC GWAS data and identified several potentially important metabolic pathways (18). To investigate whether deregulation of other pathways is critical for the development of CRC, we conducted a systems analysis using GWAS and whole transcriptome data. Our approach identified numerous hitherto unrecognized cellular pathways important for CRC occurrence, and also confirmed the substantial involvement of metabolic pathways in CRC that was first reported by Chen et al. (18). Evidence from recent epidemiologic studies also supports an association with metabolic processes, showing a link between metabolic syndrome (MS) and the risk for CRC. Kim et al. analyzed 2531 subjects including 731 CRC cases and 1800 controls and found that the prevalence for MS was 17% in patients with colorectal adenoma but only 11% in the control group (24). In keeping with 7 the latter findings, a similar study screened 1771 CRC patients and 4667 controls and observed that metabolic risk factors such as high waist circumference, blood pressure, and serum triglyceride levels were associated with an increased risk of CRC (25). In the latter cohort MS was also associated with an increased risk of adenoma (OR = 1.44, 95% CI = 1.23–1.70) (25). MS increased the risk of right colon adenomas (OR = 1.50, 95% CI = 1.22–1.85), left colon adenomas (OR = 1.36, 95% CI = 1.05–1.76), and adenomas in multiple anatomical locations (OR = 1.59, 95% CI = 1.19–2.12) (25). Recently, Esposito et al. conducted a systematic review and meta-analysis to assess the association between MS and the risk of different cancers (26). They analyzed 116 datasets from 43 articles, encompassing 38,940 cases of cancer. The presence of MS was associated with increased incidence of CRC in men (relative risk 1.25 (RR), p < 0.001) and in women (relative risk 1.34, p = 0.006) (26). Aleksandrova et al. performed a nested case-control study using 1093 CRC cases and 1093 controls (27). The results showed that among individual components of MS, abdominal obesity (RR = 1.51; 95% CI: 1.16–1.96) and abnormal glucose metabolism (RR=2.05; 95% CI 1.57–2.68) were associated with CRC (27). Teo et al. recently assessed the association between genetic risk factors of MS or related conditions and clinical outcome in stage II CRC patients (28). They analyzed the expression levels of several genes related to MS and associated alterations in two equivalent but independent sets of stage II CRC patients. The results showed that a gene expression profile constituted by genes previously related to MS was significantly associated with clinical outcome of stage II CRC patients. Despite the abundant evidence from epidemiological studies of an association between MS and CRC, such reports provide little information on the precise metabolic mechanisms that affect CRC risk. Our results therefore provide clues that may help to explain the link 8 between these two conditions and provide rational targets for potential therapeutic intervention. In addition to the metabolic pathways identified, we highlighted the involvement of pathways related to cellular processes, environmental information processing, genetic information processing, neurodegenerative diseases and the immune system in the development of CRC. Indeed, the RNA transport pathway, one of the KEGG-defined genetic information processing pathways, was the most significant pathway from analysis of CRC GWAS data (Table 1). In keeping with this finding we also observed an enrichment of significantly down-regulated genes in this pathway (Table 2). RNA transport from the nucleus to the cytoplasm is fundamental for gene expression. The different RNA species that are produced in the nucleus are exported through the nuclear pore complexes via mobile export receptors. However, general mRNA export is mechanistically different. Export of transcripts can be modulated in response to cellular signaling or stress (29). mRNA export has been found to be consistently dysregulated in primary material from many different forms of cancer. Aberrant expression of export factors can alter the export of specific transcripts encoding proteins involved in proliferation, survival, and oncogenesis. Thus, like transcription and translation, mRNA export may also play a critical role in cancer genesis and maintenance (29), and strategies to target different aspects of this pathway are now undergoing early-stage clinical trials. A variety of software tools are available for gene set (pathway) analysis of GWAS data (30). Some, such as SNP ratio test (31), GenGen (3), GRASS (18), and PLINK set-test (32), accept raw genotype datasets as input data. Others including ProxyGeneLD (22), ALIGATOR, i-GSEA4GWAS, and GESBAP (30) are used to perform initial calculation of the SNP p-values prior to subsequent gene-set analysis. In the present study we selected ProxyGeneLD for the initial gene-based test because we did not have access to raw CRC 9 genotype data. This software is capable of adjusting for gene length and LD patterns in the human genome, reducing the sources of bias and increasing the reliability of the pathway analysis. In this study, we used the pathways from the KEGG database, but not the GO database based on the following considerations. First, the KEGG database is manually compiled on the basis of biological evidence and does not have a hierarchical structure (33-34), whereas the GO database is based mainly on computer predictions as well as human annotation and has a hierarchical structure. GO analysis typically assumes that each functional category is independent, and less than 1% of the GO annotations have been confirmed experimentally (33-34). Second, Chen et al. performed a pathway analysis of CRC GWAS using KEGG pathways (18). To compare our findings with that from Chen et al., we limited our pathways from KEGG. For the expression dataset, there are two strategies for enrichment analysis of pathways: the analysis of all differentially expressed genes together or the analysis of up- and down-regulated genes separately (35). Recently, Hong, et al. examined the rationales of these enrichment analysis strategies using gene expression profiles from five types of tumors (35). They concluded that the separate analysis of up- and down-regulated genes could identify more pathways that are genuinely pertinent to phenotypic difference than analyzing all of the differentially expressed genes together (35). Based on the latter findings, we analyzed the significantly up-regulated (CRC case vs. controls) and down-regulated genes (CRC case vs. controls) separately in pathway analysis. Despite these interesting results, we recognize some limitations in our study. First, our study suffered from the usual drawback of gene set enrichment analysis resulting from use of the hypergeometric distribution to assess enrichment in pathways. This assumes that signals (i.e., pathways) are independent, which is unlikely to be the case (33-34, 36). 10 Second, multiple-testing corrections may not be sufficient to account for all biases. Ideally the results from the CRC GWAS should be adjusted using a permutation test. However, the original SNP genotype data for each individual were not originally available to us. Our intention in future is to obtain this data, and to perform additional pathway analysis using SNP ratio test (31), GenGen (3), GRASS (18), and PLINK set-test (32), which can be used to analyze the SNP genotype data, and to conduct a permutation test. Additionally, as with all findings obtained from GWAS data, further analyses are required from independent cohorts to confirm our findings. In summary, we not only provide strong evidence of the involvement of specific metabolic pathways in the development of CRC, but also highlight the involvement of pathways related to cellular processes, environmental information processing, genetic information processing, neurodegenerative diseases and the immune system. We believe that our results may advance the understanding of CRC mechanisms and will be highly useful for future genetic and clinical studies in CRC. 11 Table 1. KEGG pathways with P<0.05 by pathway analysis of CRC GWAS Pathway ID Pathway Name KEGG classification C O E R rawP adjP hsa03013 RNA transport Genetic Information Processing 151 18 3.42 5.26 1.14E-08 3.13E-07 hsa04145 Phagosome Cellular Processes 153 16 3.47 4.62 4.52E-07 8.29E-06 hsa05016 Huntington's disease Neurodegenerative diseases 183 15 4.15 3.62 2.05E-05 3.00E-04 hsa00190 Oxidative phosphorylation Metabolism 132 12 2.99 4.01 4.96E-05 5.00E-04 hsa05012 Parkinson's disease Neurodegenerative diseases 130 12 2.95 4.07 4.27E-05 5.00E-04 hsa04350 TGF-beta signaling pathway Environmental Information Processing 84 9 1.9 4.73 1.00E-04 7.00E-04 hsa04141 Protein processing in endoplasmic reticulum Genetic Information Processing 165 13 3.74 3.48 1.00E-04 7.00E-04 hsa04144 Endocytosis Cellular Processes 201 14 4.55 3.07 2.00E-04 1.00E-03 hsa04360 Axon guidance Development 129 11 2.92 3.76 2.00E-04 1.00E-03 hsa03040 Spliceosome Genetic Information Processing 127 11 2.88 3.82 2.00E-04 1.00E-03 hsa00564 Glycerophospholipid metabolism Metabolism 80 8 1.81 4.41 5.00E-04 2.10E-03 hsa04810 Regulation of actin cytoskeleton Cellular Processes 213 13 4.83 2.69 1.20E-03 4.40E-03 hsa00051 Fructose and mannose metabolism Metabolism 36 5 0.82 6.13 1.20E-03 4.40E-03 hsa05110 Vibrio cholerae infection Infectious diseases: Bacterial 54 6 1.22 4.9 1.40E-03 4.80E-03 hsa03008 Ribosome biogenesis in eukaryotes Genetic Information Processing 80 7 1.81 3.86 2.30E-03 7.40E-03 hsa04080 Neuroactive ligand-receptor interaction Environmental Information Processing 272 14 6.16 2.27 4.00E-03 1.16E-02 hsa00230 Purine metabolism Metabolism 162 10 3.67 2.72 4.00E-03 1.16E-02 hsa00520 Amino sugar and nucleotide sugar metabolism Metabolism 48 5 1.09 4.6 4.50E-03 1.24E-02 12 hsa05010 Alzheimer's disease Neurodegenerative diseases 167 10 3.78 2.64 5.00E-03 1.31E-02 hsa00330 Arginine and proline metabolism Metabolism 54 5 1.22 4.09 7.50E-03 1.88E-02 hsa04260 Cardiac muscle contraction Circulatory system 77 6 1.74 3.44 8.10E-03 1.94E-02 hsa04010 MAPK signaling pathway Environmental Information Processing 268 13 6.07 2.14 8.70E-03 1.99E-02 hsa00590 Arachidonic acid metabolism Metabolism 59 5 1.34 3.74 1.08E-02 2.38E-02 hsa03015 mRNA surveillance pathway Genetic Information Processing 83 6 1.88 3.19 1.15E-02 2.43E-02 hsa05215 Prostate cancer Cancers: Specific types 89 6 2.02 2.98 1.58E-02 3.04E-02 hsa04540 Gap junction Cellular Processes 90 6 2.04 2.94 1.66E-02 3.04E-02 hsa00830 Retinol metabolism Metabolism 64 5 1.45 3.45 1.50E-02 3.04E-02 hsa04510 Focal adhesion Cellular Processes 200 10 4.53 2.21 1.64E-02 3.04E-02 hsa05211 Renal cell carcinoma Cancers: Specific types 70 5 1.59 3.15 2.13E-02 3.66E-02 hsa03320 PPAR signaling pathway Endocrine system 70 5 1.59 3.15 2.13E-02 3.66E-02 hsa04630 Jak-STAT signaling pathway Environmental Information Processing 155 8 3.51 2.28 2.54E-02 4.23E-02 hsa04612 Antigen processing and presentation Immune system 76 5 1.72 2.9 2.92E-02 4.46E-02 hsa04620 Toll-like receptor signaling pathway Immune system 102 6 2.31 2.6 2.87E-02 4.46E-02 hsa04370 VEGF signaling pathway Environmental Information Processing 76 5 1.72 2.9 2.92E-02 4.46E-02 C, number of reference genes in the category; O, number of genes in the gene set and also in the category; E, expected number in the category; R, ratio of enrichment, rawP, p value from hypergeometric test; adjP, p value adjusted by the multiple test adjustment. 13 Table 2. KEGG pathways with P<0.05 using human CRC up-regulated genes CRC up-regulated genes Pathway ID CRC down-regulated genes Pathway Name C O E R rawP adjP C O E R rawP adjP hsa03013 RNA transport 151 N N N N N 151 13 2.65 4.9 3.00E-06 8.92E-06 hsa04145 Phagosome 153 18 2.03 8.85 2.84E-12 8.99E-11 153 17 2.69 6.32 2.04E-09 1.41E-08 hsa05016 Huntington's disease 183 14 2.43 5.76 1.91E-07 7.56E-07 183 21 3.22 6.53 1.42E-11 3.04E-10 hsa00190 Oxidative phosphorylation 132 11 1.75 6.27 1.68E-06 4.99E-06 132 16 2.32 6.9 1.69E-09 1.29E-08 hsa05012 Parkinson's disease 130 12 1.73 6.95 1.88E-07 7.56E-07 130 17 2.28 7.44 1.57E-10 1.68E-09 hsa04350 TGF-beta signaling pathway 84 7 1.12 6.27 1.00E-04 2.00E-04 84 11 1.48 7.45 2.67E-07 1.10E-06 hsa04141 Protein processing in endoplasmic reticulum 165 8 2.19 3.65 1.70E-03 2.20E-03 165 19 2.9 6.55 1.25E-10 1.49E-09 hsa04144 Endocytosis 201 11 2.67 4.12 8.79E-05 2.00E-04 201 21 3.53 5.94 8.48E-11 1.30E-09 hsa04360 Axon guidance 129 10 1.71 5.83 9.48E-06 2.50E-05 129 6 2.27 2.65 2.68E-02 2.68E-02 hsa03040 Spliceosome 127 5 1.69 2.96 2.76E-02 2.79E-02 127 13 2.23 5.82 4.18E-07 1.60E-06 hsa04810 Regulation of actin cytoskeleton 213 17 2.83 6.01 5.02E-09 3.67E-08 213 14 3.74 3.74 2.82E-05 6.16E-05 hsa05110 Vibrio cholerae infection 54 6 0.72 8.36 8.06E-05 1.00E-04 54 5 0.95 5.27 2.60E-03 2.90E-03 hsa04080 Neuroactive ligand-receptor interaction 272 9 3.61 2.49 1.11E-02 1.17E-02 272 N N N N N hsa00230 Purine metabolism 162 6 2.15 2.79 2.16E-02 2.21E-02 162 9 2.85 3.16 2.40E-03 2.70E-03 hsa05010 Alzheimer's disease 167 13 2.22 5.86 4.26E-07 1.40E-06 167 17 2.94 5.79 7.80E-09 4.39E-08 hsa00330 Arginine and proline metabolism 54 N N N N N 54 7 0.95 7.38 4.36E-05 7.78E-05 hsa04260 Cardiac muscle contraction 77 7 1.02 6.84 7.59E-05 1.00E-04 77 10 1.35 7.39 1.01E-06 3.49E-06 14 hsa04010 MAPK signaling pathway 268 16 3.56 4.49 7.60E-07 2.41E-06 268 23 4.71 4.88 5.64E-10 5.03E-09 hsa03015 mRNA surveillance pathway 83 N N N N N 83 5 1.46 3.43 1.56E-02 1.61E-02 hsa05215 Prostate cancer 89 10 1.18 8.46 3.15E-07 1.07E-06 89 9 1.56 5.75 2.77E-05 6.16E-05 hsa04540 Gap junction 90 5 1.2 4.18 7.10E-03 7.80E-03 90 9 1.58 5.69 3.03E-05 6.48E-05 hsa00830 Retinol metabolism 64 N N N N N 64 6 1.12 5.33 9.00E-04 1.10E-03 hsa04510 Focal adhesion 200 28 2.66 10.54 2.15E-20 2.04E-18 200 19 3.52 5.41 3.31E-09 1.97E-08 hsa05211 Renal cell carcinoma 70 6 0.93 6.45 3.00E-04 5.00E-04 70 11 1.23 8.94 3.88E-08 2.08E-07 hsa03320 PPAR signaling pathway 70 5 0.93 5.38 2.40E-03 3.00E-03 70 N N N N N hsa04630 Jak-STAT signaling pathway 155 10 2.06 4.86 4.65E-05 9.40E-05 155 9 2.72 3.3 1.80E-03 2.10E-03 hsa04612 Antigen processing and presentation 76 5 1.01 4.95 3.50E-03 4.10E-03 76 14 1.34 10.48 6.00E-11 1.07E-09 hsa04620 Toll-like receptor signaling pathway 102 11 1.36 8.12 1.24E-07 5.61E-07 102 10 1.79 5.58 1.32E-05 3.07E-05 hsa04370 VEGF signaling pathway 76 5 1.01 4.95 3.50E-03 4.10E-03 76 8 1.34 5.99 5.78E-05 9.82E-05 C, number of reference genes in the category; O, number of genes in the gene set and also in the category; E, expected number in the category; R, ratio of enrichment, rawP, p value from hypergeometric test; adjP, p value adjusted by the multiple test adjustment. N, Null. 15