Background: It has been hypothesized that the early detection of lung and head and neck cancer would improve diagnosis and prognosis. For such an approach to be successful, specific and novel markers must be identified. These markers should have high sensitivity and specificity and appear at a pre-clinical stage of the disease. They must also ideally be detectable in a biological fluid that can be obtained using minimally invasive strategies. There is growing evidence that hypermethylation of CpG-rich sequences in the promoter regions of tumour suppressor genes such as RAR beta may lead to long-term transcriptional silencing of such genes and thus contribute to tumour development.
Methods: Methylation Specific PCR (MSP) after bisulphite treatment was used to investigate whether aberrant methylation of the RAR beta gene occurs in 24 primary lung and 20 head and neck cancer samples. Expression analysis was performed using semi-quantitative, comparative, mulitplex RT-PCR.
Results: Results obtained from the analysis of genomic DNA in the RAR beta promoter region from 44 pairs of tumour/normal tissue showed inter-analysis variability, indicating that more stringent protocols need to be developed. Expression analysis has revealed differential expression patterns between tumour and control tissue.
Conclusions: Preliminary results show the need for the development of more stringent methods for assessing CpG methylation. Expression analysis has also demonstrated the expression of all three isoforms and that there maybe a possible link between loss of expression and methylation status.
This work was funded by the Department of Clinical Dental Sciences at the University of Liverpool, UK.