Suppressed Expression Of Pokemon Gene In Hela Cells By Retrovirus-mediated RNAi

Pokemon gene is aberrantly overexpressed in human cancer such as T and B cell lymphoma, breast cancer, lung cancer, colon cancer, prostate cancer and bladder cancer, which suggests the critical role of Pokemon in tumorigenesis. Members of the POK family proteins contain an amino-terminal POZ domain and a carboxy-terminal DNA-binding domain making of Kru¨ppel-type zinc fingers. It can act as potent transcriptional repressors through the recruitment of histone deacetylases and subsequent chromatin remodeling. POK proteins are also important in embryonic development, differentiation and oncogenesis. Pokemon (for POK erythroid myeloid ontogenic factor; also known as LRF10, OCZF11 and FBI-1), encoded by Zbtb7 gene, is a POK protein family member that has a pivotal and pleiotropic function in cellular differentiation and can physically interact with other POK family members. Mouse embryonic fibroblasts lacking Zbtb7 are completely refractory to oncogene (such as E1A, Ras, Myc, T-Ag)-mediated cellular transformation and overexpression of Pokemon gene leads to tumorigenesis in transgenic mice. It has also been proved that Pokemon can specifically repress the transcription of the tumour suppressor gene ARF through direct binding. The model for the role of Pokemon in oncogenesis is hypothesized as Pokemon↑↑→ARF↓→MDM2→p53↓→tumorigenesis. Thus, Pokemon gene should be an appropriate target in terms of gene therapy.RNA interference (RNAi) strategy has been adopted to tumor-targeting gene therapy. RNAi phenomenon exists in a wide range of species and is a highly conserved process in evolution and a self-defense mechanism, so it is also called as the"the immune system of genome". The basic mechanism of RNAi has been studied detailedly: long dsRNA is cleaved into 21-23bp small double-strand RNAs (or called small interfering RNA, siRNA) by Dicer complex that was grouped to RNase III family nuclease. The antisense strand of siRNA along with other components are incorporated into RISC (RNA-induced silencing complex), and then destroys the complementary sequence of target mRNA. To date, RNAi...