The utility of the Ion Torrent PGM next generation sequencing for analysis of the most commonly mutated genes among patients with colorectal cancer in India

Background: The requirement for the mutation analysis for Kirsten rat sarcoma viral oncogene (KRAS) in colorectal cancer (CRC) is rapidly increasing as it is a predictive biomarker and also, its absence signifies response to anti?epidermal growth factor receptor (anti?EGFR) antibody treatment. The aim of our study was to investigate the pathological diagnosis and distribution of KRAS mutations in colorectal cancer with the use of next generation sequencing platform (Ion Torrent). Methods: A total of 56 CRC samples were tested to identify the genetic mutations, especially KRAS using the primers which included ~2800 COSMIC mutations of 50 oncogenes. Ion Torrent personal genome machine (semiconductor?based sequencing) was used for the sequencing and analysis. Along with KRAS, other 49 genes were also studied for COSMIC mutations. Results: KRAS mutation 25 (44.6%) had the highest frequency, followed by TP53 10 (17.9%) and PIK3CA mutation 4 (7.1%). Of all the KRAS mutations identified, mutations in codon 12 were most frequent followed by mutations in codon 13 and 61. The most frequent substitution was glycine to aspartate mutation in codon 12 (p.Gly12Asp) followed by glycine to valine (p.Gly12Val). Combinations of mutations were also studied. Our study revealed that seven cases (12.5%) had both KRAS and TP53 mutations (highest of all the combinations). Conclusion: The analysis of KRAS mutation frequency and its mutational subtype analysis in human CRCs by using semiconductor?based platform in routine clinical practices have been performed in Indian population. The findings were similar to earlier published reports from the Western literature.

Expressions and Significance of p21 Protein and K-ras Protein in Congenital Biliary Dilatation / 实用儿科临床杂志

Objective To investigate the expressions and significance of p21 protein and K-ras protein in congenital biliary dilatation(CBD),and their relationship.Methods Surgical specimens of CBD were obtained during operation on 36 children from Jan.2000 to Sep.2007.Nine normal bile ducts specimens from miscarried fetus and children's corpse.The specimens were fixed in 40 g?L-1 formalin and embeded by paraffin,slice-fixed.SP immunohistochemical method was used to detect the expressions of p21 protein and K-ras protein.Results The positive rate of K-ras protein was 13.8% in CBD,which was significantly higher than that in normal bile duct tissues.The positive rate of p21 protein was 55.6% in CBD,and 100% in normal bile duct tissues.p21 protein positive expression rate in CBD was significantly lower than that in normal bile duct tissues(P