The detection of the expression of Keratin 19 and Keratin 20 genes in the diagnosis of micrometastases of colonic cancers

Abstract

OBJECTIVE: Keratin 19(K-19) and Keratin 20(K-20) genes are expressed in the epithelial tissues while they are absent in lymphoid-tissues. Therefore the expression of these foreign genes in lymph nodes is used in the diagnosis of micrometastases. We investigated the expression of K19 and K2C in the diagnosis of micrometastases of colonic cancer. DESIGN, SETTING AND METHODS: Regional lymph nodes of patients with colonic cancer (n = 5) were obtained from University Surgical Unit of Ragama. Two corresponding lymph nodes from non-cancer patients and colonic tumor tissue were used as negative and positive control respectively. De-ionized water was used as blank control. Lymph nodes were collected directly to the RNA extracting media (Isogen) during the surgery. Specimens were transported to Medical Research Institute within one hour at 4 C. cDNA was synthesized using reverse transcriptase and K19 and K20 primers were used to detect the expression of these genes. PCR products were identified using agarose gel electrophoresis after amplification using the thermal cycler (Perkin Elmer). (3-actin primer was used for internal quality control. RT/PCR findings were compared with the routine histological findings of the patients. RESULTS: Lymph nodes of all five patients with colonic cancers and the colonic cancer tissues were positive for the expression of K19 and K 20. Both control lymph nodes were negative for the expression of K-19 and K-20. All the patients with colonic cancers were negative on histology of the lymph node biopsies. CONCLUSION: These findings suggest that the detection of the expression of K19 and K20 help to identify the metastases, which are negative on histology.