Study on Detecting Colorectal Cancer Micrometastases in Lymph Nodes by Nested Reverse Transcriptase-Polymerase Chain Reaction Amplification of Cytokeratin 20 and Matrix Metalloprotreinase-7

Objective To develop a nested reverse transcriptase polymerase chain reaction method to amplify Cytokeratin 20mRNA and Matrix Metalloproteinase-7mRNA for detecting colorectal cancer micrometastases in lymph nodes .Methods The RT-PCR system was set up by using nest primer. The presence of CK20 mRNA and MMP-7 mRNA was investigated by nested RT-PCR in 100 lymph nodes from 30 colorectal cancer patients who underwent curative operation. Tweenty-five lymph nodes from 10 patients with benign intestinal disease were served as negative control. The results of nested RT-PCR were compared with ones of routine histology.Results The positive rate of CK20 mRNA and MMP-7 mRNA in 187 lymph nodes from 30 colorectalcancer patients was 40.11% (75/187), 51.87% (97/187) respectively,while only 57 samples were histologically positive.The expression of CK20 mRNA and MMP-7 mRNA in 25 lymph nodes of 10 cases of control group were all negative.Conclusion Nested reverse transcriptase polymerase chain reaction was a sensitive and specific method to indicate the expression of CK20 mRNA and MMP-7 mRNA in lymph nodes as a helpful marker of micrometastases of colorectal carcinoma cells. It is superior to routine histopathological assay in examing lymph node metastases. The detection of CK20 mRNA and MMP-7 mRNA in lymph nodes may contribute to improve the accuracy of clinical staging, determine patients' prognosis and provide information for adjuvant therapy.