Reliable Reference Gene for Normalization of RTqPCR Data in Human Cancer Cell Lines Subjected to Gene Knockdown

Quantitative real-time Polymerase Chain Reaction (RT-qPCR) has become a valuable molecular technique in biomedical research. The selection of suitable endogenous reference genes is necessary for normalization of target gene expression in RT-PCR experiments. The aim of this study was to determine the suitability of each 18S rRNA and ACTB as internal control genes for normalization of RT-qPCR data in some human cell lines transfected with small interfering RNA (siRNA). Four cancer cell lines including MCF-7, T47D, MDA-MB-231 and Hela cells along with HEK293 representing an embryonic cell line were depleted of E2F6 using siRNA specific for E2F6 compared to negative control cells, which were transfected with siRNA not specific for any gene. Using RT-qPCR, Ct (threshold cycle) values of 1 S and ACTB were determined in transfected cells and compared with control cells. In the selection of the above cell lines, 18S was identified as the most stably expressed reference gene than ACTB in gene knockdown experiments.