Objective: To introduce a new method for studies on methylation status of CpG island: methylation specific polymerase chain reaction (MSP) with some modifications.
Methods: Target DNA was modified by sodium bisulfite, converting all unmethylated, but not methylated, cytodines to uracil, and subsequent amplification with primers specific for methylated versus unmethylated DNA. The status of 5'CpG island of tumor suppressor gene p16 in maxilliofacial squamous cell carcinoma (MSCC) was analyzed by modified MSP assay.
Results: To get single strand DNA, the authors denatured the target DNA by heating instead of alkaline treatment. DNA purification kit was also replaced by dialysis. A cheaper restriction enzyme Taq I was used in place of BstU I to distinguish methylated fragment from unmethylated fragment. The 5'CpG island of p16 gene was methylated in some MSCC tumors.
Conclusion: MSP is a simple, sensitive, and specific method for detecting the methylation status of any CpG-rich region and the modifications make it more simple to perform.