Rapid and sensitive assay of K-ras mutations in pancreatic cancer by electrochemical detection with ferrocenyl-naphthalene-diimide

The DNA chip is a very powerful tool for genetic analysis. Conventional DNA chips that utilize fluorescence detection systems are very complicated, expensive and impractical, but the electrochemical array (ECA) chip is gaining popularity. To investigate the validity of the ECA chip, which utilizes ferrocenyl-naphthalene-diimide (FND), k-ras mutations in 20 pancreatic cancer tissues were examined. DNA was isolated from 20 pancreatic cancer tissues and subjected to a 2-stage polymerase chain reaction (PCR). The k-ras mutations were detected with the ECA chip. To verify the reliability of the ECA chip, the DNA was also analyzed by direct sequencing and the PCR-dependent preferential homoduplex formation assay (PCR-PHFA). The ECA chip could detect one mutation in a background of 1000 wild-type DNAs. K-ras mutations were identified in 17 out of 20 (85%) pancreatic cancer samples. Three mutations of codon 12 of k-ras, GTT, GAT and AGT, were detected. K-ras mutations were detected in 13 out of 20 (65%) samples by sequencing and in 17 out of 20 (85%) samples by PCR-PHFA. These findings were concordant with the ECA chip result. The FND-ECA chip is a sensitive, rapid and reliable method for screening point mutations in a variety of clinical samples.