RASAL1 is a major tumor suppressor gene in thyroid cancer
The present invention relates to the field of cancer. More specifically, the present invention provides methods and compositions useful for treating thyroid cancer. In certain embodiments, the method comprises the steps of (a) treating DNA isolated from a sample collected from the patient using bisulfite; (b) measuring the DNA methylation level of the promoter region of the RASAL1 gene from the bisulfite-treated DNA using methylation-specific polymerase chain reaction (MSP), wherein the MSP creates a methylation and unmethylation band; (c) normalizing the measured DNA methylation level using an internal reference gene; (d) calculating the percentage of allelic methylation using the formula [M/(M+U]×100%, wherein M and U represent the density of the methylation and unmethylation band; and (e) predicting an increased risk of thyroid cancer in the subject if the percentage of allelic methylation is at least 40%.
1. A method for predicting an increased risk of thyroid cancer in a patient comprising the steps of:
(a) PCR amplifying exons 13, 14, 15, and 17 of the RASAL1 gene from DNA isolated from a sample collected form the patient to produce a separate PCR product for each of the exons, wherein the amplified products comprise nucleotide 1031 of Exon 13, nucleotides 1153, 1201, 1303, 1312, and 1313 of exon 14, nucleotide 1422 of exon 15, and nucleotide 1782 of exon 17, wherein nucleotide 1 is defined as the A of the ATG translation initiation codon of the RASAL1 gene;
(b) sequencing the PCR amplification products; and
(c) detecting the presence of one or more of a G at position 1031, a T at position 1153, an A at position 1201, a T at position 1303, a T at position 1312, an A at position 1313, an A at position 1422, and an A at position 1782; and
(d) predicting an increased risk of thyroid cancer.
2. The method of claim 1 , wherein the following primers are used for the PCR amplification step: SEQ ID NOS:57-58 for Exon 13; SEQ ID NOS:59-60 for Exon 14, SEQ ID NOS:61-62 for Exon15, and SEQ ID NOS:65-66 for Exon 17.