Objective: To clone novel metastasis-associated genes of colorectal carcinoma and provide clues for the molecular mechanisms of metastasis of colorectal carcinoma.
Methods: By suppression subtractive hybridization (SSH), a pair of colorectal carcinoma cell lines with different metastatic potentials derived from the same parental cell line was used to construct two subtractive cDNA library specific for metastasis-accelerating genes or metastasis-suppressor genes. Partial positive clones in the two libraries were selected randomly and differentially screened, and the differentially expressed gene fragments obtained were sequenced and analyzed with BLAST software. The mRNA expressions of several new genes were confirmed by Northern blot analysis.
Results: Two subtractive cDNA libraries had 235 and 232 white clones respectively and more than 90% of the white clones had the inserts. About 200 positive clones selected randomly were differentially screened, and 29 differentially expressed genes were obtained. Fifteen unknown genes were found by sequence and BLAST analysis and had been collected by the GenBank dbEST database with the entry number of CD485499 to CD485513, among which 6 novel genes were located in the fifth chromosome.
Conclusion: SSH is a reliable strategy for screening novel genes differentially expressed in metastasis of colorectal carcinoma. The fifth chromosome may harbor many new genes related with metastasis of colorectal carcinoma, and identified new genes can be cloned for their full length for further study of their functions.