Detection of mitochondrial DNA alterations in primary tumors and corresponding serum of colorectal cancer patients

We previously examined colorectal cancer patients using mutation-specific m ismatch ligation assay for genetic alterations in primary tumors and paired serum samples and proved that genetic alterations present in the tumors of cancer patients can be detected in the serum of those same patients. Recen t evidence has proved that various cancers frequently have mutations in the D-loop region of mitochondrial DNA (mtDNA). Therefore, we thought that mut ations in the mitochondrial genome might also become a genetic marker of co lorectal cancer to detect tumor DNA in the serum of patients. We first sequ enced the D-loop region of mtDNA in colorectal cancers. We then proceeded w ith a sensitive method, i.e., mismatch ligation assay to examine the possib ility that mtDNA alterations can be found in the serum DNA. We analyzed the D-loop region of mtDNA in 77 primary colorectal cancers, 7 of which (9%) c ontained true somatic mutations in this region. We then examined whether mt DNA alterations can be found in the serum DNA using mismatch ligation assay . Of 7 alterations that were examined, 1 (14%) could be detected in the ser um. This result suggested that the mtDNA alteration could also be used as a tumor marker to detect tumor DNA in the serum. (C) 2001 Wiley-Liss, Inc.