Methylation specific PCR to characterize methylation of the promoter of deoxycytidine kinase.

Deoxycytidine kinase (dCK) is essential for phosphorylation of natural deoxynucleosides and analogs, such as gemcitabine and cytarabine, two widely used anticancer compounds. We hypothesized that DNA methylation of SP1 binding sites in the dCK promoter region might affect dCK expression. Using methylation specific PCR (MSP), methylation was detected in one of the SP1 binding sites of the dCK promoter, in most tested cancer cell lines and in patient samples from brain tumors and leukemia. This SP1 site is a 3'GC box, which upon hypomethylation negatively regulates dCK mRNA expression. In conclusion, we developed a new MSP method showing methylation of the 3' GC-box in the dCK promoter region in tumor cells and patient samples. Methylation might therefore regulate transcription of dCK, and should be studied further to understand its role in influencing gemcitabine and cytarabine activity.