An integrated approach to the detection of colorectal cancer utilizing proteomics and bioinformatics

AIM: To find new potential biomarkers and to establish patterns for early detection of colorectal cancer.METHODS: One hundred and eighty-two serum samples including 55 from colorectal cancer (CRC) patients, 35 from colorectal adenoma (CRA) patients and 92 from healthy persons (HP) were detected by surface-enhanced laser desorption/ionization mass spectrometry (SELDI-MS). The data of spectra were analyzed by bioinformatics tools like artificial neural network (ANN) and support vector machine (SVM).RESULTS: The diagnostic pattern combined with 7 potential biomarkers could differentiate CRC palJents from CRA patients with a specificity of 83%, sensitivity of 89% and positive predictive value of 89%. The diagnostic pattern combined with 4 potential biomarkers could differentiate CRC patients from HP with a specificity of 92%, sensitivity of 89% and positive predictive value of 86%.CONCLUSION: The combination of SELDI with bioinformatics tools could help find new biomarkers and establish patterns with high sensitivity and specificity for the detection of CRC.

Effect of the Flanking Sequence Architecture of Translation Initiation AUG Codon on Gene Expression Level in Rice

The relationship between the codon usage bias, gene expression level and the AUG context(from -20 to +6 positions relative to the initiator AUG codon) was examined in 541unigene sequences of rice. A significant correlation for CAI values (codon adaptationindex) was observed at five nucleotide positions (-19, -18, -9, -4, +5), eight (-19, -18,-14, -9, -6, -4, -1, +5) for CPP (codon preference parameter), and seven (-18, -16, -15,-9, -7, -1, +6) for mRNA abundance in the flanking sequence of the initiator AUG codonrespectively, but a significantly positive correlation for both CAI and CPP at twopositions (-4 and +5), indicating that both those positions are evolutionally under thenatural selection constraint at the translational level. By site-directed mutagenesis atseven specific positions (-18, -16, -15, -9, -7, -1 and +6) for allergenic protein thathad the highest mRNA abundance in this study, its expression level decreased dramatically63.3 and 72.5% respectively, indicating the importance of those 7 positions for geneexpression. A highly positive correlation (r=0.625, P<0.01) between AUGCAI and GCcontent in the flanking sequence of the initiator AUG codon showed a more effectivehigher GC content on translation initiation efficiency. The strong preference for G orC at those 8 positions (-6, -5, -3, -2, -1, +4, +5 and +6) in the AUG context suggestedthat an important factor in modulation of the translation efficiency, as well assynonymous codon usage bias, particularly in highly expressed genes.

Gene Identification and Expression Analysis of 86,136 Expressed Sequence Tags(EST)from the Rice Genome

Expressed Sequence Tag (EST) analysis has pioneered genome-wide gene discovery and expression profiling. In order to establish a gene expression index in the rice cultivar indica, we sequenced and analyzed 86,136 ESTs from nine rice cDNA libraries from the super hybrid cultivar LYP9 and its parental cultivars. We assembled these ESTs into 13,232 contigs and leave 8,976 singletons. Overall, 7,497 sequences were found similar to the existing sequences in GenBank and 14,711 are novel. These sequences are classified by molecular function, biological process and pathways according to the Gene Ontology. We compared our sequenced ESTs with the publicly available 95,000 ESTs from japonica, and found little sequence variation, despite the large difference between genome sequences. We then assembled the combined 173,000 rice ESTs for further analysis. Using the pooled ESTs, we compared gene expression in metabolism pathway between rice and Arabidopsis according to KEGG. We further profiled gene expression patterns in different tissues, developmental stages, and in a conditional sterile mutant, after checking the libraries are comparable by means of sequence coverage. We also identified some possible library specific genes and a number of enzymes and transcription factors that contribute to rice development.

EST-based Analysis of Gene Expression in the Porcine Brain

Since pig is an important livestock species worldwide, its gene expressionhas been investigated intensively, but rarely in brain. In order to study gene expression profilesin the pig central nervous system, we sequenced and analyzed 43,122 high-quality 5'' end expressedsequence tags (ESTs) from porcine cerebellum, cortex cerebrum, and brain stem cDNA libraries,involving several different prenatal and postnatal developmental stages. The initial ESTs wereassembled into 16,101 clusters and compared to protein and nucleic acid databases in GenBank. Ofthese sequences, 30.6% clusters matched protein databases and represented function known sequences;75.1% had significant hits to nucleic acid databases and partial represented known function; 73.3%matched known porcine ESTs; and 21.5% had no matches to any known sequences in GenBank. We used thecategories defined by the Gene Ontology to survey gene expression in the porcine brain.

Construction of fine SNP haplotypes and haplotype blocks in 5 genes in the centromere of chromosome 15 in Chinese Han subjects

Recent advances have shown that the majorityof the nucleotide variation in human genome is single nucleo-tide polymorphisms (SNPs). Using SNPs each chromosomecan be divided into different haplotype blocks, and there arelimited common haplotypes in each block. This provides apowerful approach for whole genome scan for disease-asso-ciated genes/variants. However, most data available todayare based on the large-scale genomic analyses, data concern-ing individual genes for fine mapping with high density SNPsare relatively lacking. We have sequenced 7 genes and theirflanking regions, identified 34 novel SNPs, constructed highdensity SNP haplotypes and haplotype blocks in 5 genes inthe centromeric region of chromosome 15 in I00 ChineseHart subjects. Our results show that there is a great hetero-geneity in the haplotypes and haplotype block structureswithin and between these genes, which are in close physicalproximity. Data obtained in this study provide a useful toolfor candidate gene approach at the fine scale for identifyingdisease contributing variants in the genes/regions.

Gene Expression Profiling in Porcine Fetal Thymus

To obtain an initial overview of gene diversity and expression pattern in porcine thymus, 11,712 ESTs (Expressed Sequence Tags) from 100-day-old porcine thymus (FTY) were sequenced and 7,071 cleaned ESTs were used for gene expression analysis. Clustered by the PHRAP program, 959 contigs and 3,074 singlets were obtained. Blast search showed that 806 contigs and 1,669 singlets (totally 5,442 ESTs) had homologues in GenBank and 1,629 ESTs were novel. According to the Gene Ontology classification, 36.99% ESTs were cataloged into the gene expression group, indicating that although the functional gene (18.78% in defense group) of thymus is expressed in a certain degree, the 100-day-old porcine thymus still exists in a developmental stage. Comparative analysis showed that the gene expression pattern of the 100-day-old porcine thymus is similar to that of the human infant thymus.

Structure Prediction of Membrane Proteins

There is a large gap between the number of membrane protein (MP) sequencesand that of their decoded 3D structures, especially high-resolution structures, due to difficultiesin crystal preparation of MPs. However, detailed knowledge of the 3D structure is required for thefundamental understanding of the function of an MP and the interactions between the protein and itsinhibitors or activators. In this paper, some computational approaches that have been used topredict MP structures are discussed and compared.

Identification and Expression Analysis of EST-based Genes in the Bud of Lycoris longituba

To obtain a primary overview of gene diversity and expression pattern inLycoris longituba, 4,992 ESTs (Expressed Sequence Tags) from L. longituba bud were se-quenced and4,687 cleaned ESTs were used for gene expression analysis. Clustered by the PHRAP program, 967contigs and 1,343 singlets were obtained. Blast search showed that 179 contigs and 227 singlets(totally 1,066 ESTs) had homologues in GenBank and 3,621 ESTs were novel.