Screening for epigenetically masked genes in colorectal cancer using 5-aza-2′-deoxycytidine, microarray and gene expression profile

Aim: Unearthing of silenced genes in colorectal cancer (CRC). Materials and Methods: Oligonucleotide microarray was used in order to find changes in gene expression in five CRC cell lines before and after 5-aza-2′-Deoxycitidine treatment. Up-regulated genes were integrated with expression profile of matched colorectal tissue samples. Methylation-specific polymerase chain reaction and Real-time quantitative reverse transcription polymerase chain reaction were used to further analyze candidates using 15 CRC cell lines and 23 paired samples. Results: After applying study selection criteria for 68 genes obtained from integrated arrays, we identified 16 genes; apoptosisstimulating of p53 protein 1 (ASPP1) and Scavenger receptor class A, member 5 (SCARA5) were selected for further analysis. Methylation was only identified for SCARA5 in 20% of the cell lines and in 17% of tumor the samples. Down expression of SCARA5 was observed in CRC cell lines and in tumor samples compared to normal (p<0.001 and p=0.001, respectively). Conclusion: Genome-wide screening identifies genes potentially affected by methylation in CRC. SCARA5 may have a role in tumorigenesis in CRC.