ANALYSING MITOCHONDRIAL GENOME IN THE DEVELOPMENT OF OESOPHAGEAL CANCER
F Mudimbu, Dr K Chapman, Pro G Jenkins, Dr M. Hitchings and R Lawrence.
DNA Damage and Cancer Research Group, Institute of Life Science, Swansea University, Swansea, SA2 8PP.
Oesophageal cancer forms from a precursor lesion (Barrett’s oesophagus) which is a metaplasia of squamous epithelial cells. It affects 1 in 55 men and 1 in 115 women worldwide. There are two types of oesophageal adenocarcinoma cancer which are (OAC) and squamous cell carcinoma (SCC). OAC is more common in Western Europe and is the most aggressive subtype of oesophageal cancer. Mitochondrial DNA (mtDNA) mutations are more common in cancer and therefore may be an important diagnostic biomarker. Mitochondrial DNA (mtDNA) is a circular double stranded DNA sequence which is 16 569 base pairs and is maternally inherited.
To optimise the long-range Polymerase Chain Reaction (PCR) for mtDNA extracted from human blood. To compare mtDNA copy number between each phase in the development of OAC. To find the relationship between the stages of oesophageal cancer in terms of single nucleotide polymorphisms (SNPs) and gene mutations.
Overall purpose: Ultimately, mutations in mtDNA may offer a blood biomarker for oesophageal cancer progression, offering a less invasive diagnostic test compared to endoscopy procedures
MtDNA extraction from blood samples using Qi amp technique and amplified using PCR techniques. The three mtDNA fragments were sequenced using Illumina Miseq technique and data analysed using the mtDNA server.
MT DNA copy number (CNV) gradually decreases with the development of oesophageal cancer. Amplification of Mt DNA extracted from blood also shows that it is possible to amplify 5-6kb fragments. Heteroplasmies can only be detected at high coverage mean read depth of above 750. Heteroplasmies detected in OAC samples in the Mt-ND2 region gene region.
Results from long PCR show that 5-6kb fragments of mtDNA can be amplified. MtDNA loses its integrity with the development of cancer. Heteroplasmies detected can be a useful biomarker in oesophageal cancer diagnosis.