Outline an experiment that can be done to test this correlat

Outline an experiment that can be done to test this correlation between methylation and tumor evolution. Be specific. What specific areas are important for future clarifications?

Solution

DNA methylation is a stable genome modification that can help us gather information about tumor\'s origin and also its evolution. DNA methylation varies across the genome showing higher methylation at repeat sequences and retrotransposons and lower methylation at CpG islands and active gene promoters. CpG islands at cancer cells has low variance in methylation whereas at adjacent non cancer cells , there is a high variation in DNA methylation.

To test correlation between DNA methylation and tumor evolution

Cell lines on which the DNA methylation have to be carried out has to be selected, in this case, the cell lines selected are prostate cancer cell lines and a normal cell line from the same tissue as control to check the DNA methylation in both the tissues simultaneously. After selection of both the cell lines, methylation profiling requires to be done. It is imporatant that while selecting the tissue for methylation profiling the age of both tumor and normal cells have to be same. Also, since certain cancer types show a field effect,i.e. change the normal cells adjacent to the cancer cells, the normal cells selected should be such that it shoulld not have undergone this neoplastic change. Also, utmost care should be taken that the normal cells selected should be completely tumor free.

Methylation profiling can be done using a number of techniques, most successful and reproducible of which is the INFINIUM 450k array, which is preferred for its higher reproducibility. Mean methylation would be lesser in normal tissue as compared to the tumor tissue, for prostate cancer cell lines and prostate tissue cell lines.

For early indications of tumourigenesis there will be higher recurrence rate in DNA methylation. A ll the other results and conclusions can be drawn while performing the experiment.