The effect of knocking-down nucleostemin gene expression on the in vitro proliferation and in vivo tumorigenesis of HeLa cells

Previous studies have demonstrated nucleostemin (NS) expressed in undifferentiated cells (e.g. embryonic stem cells and myeloid stem cells) and various cancer cell lines, but didn't express in differentiated adult tissues. In this study, we examined the NS expression in several cancer cell lines and some normal human tissues. Moreover, we used RNAi techniques to knock down the NS gene expression in Hela cells. As a result, we found that all these detected cancer cell lines in our program had high levels of NS expression, which indicated NS played a really important role in the self-renewal of these cancer cells. At the same time, NS expressed in human placenta tissue also at a high level, which may be due to the existence of a mass of placenta stem cells. Only a small quantity of NS expression could be found in normal human muscle tissue due to the existence of myoblasts. And for the first time our findings demonstrated that if NS expression of Hela cells was knocked down, more Hela cells couldn't complete the DNA synthesis to pass through S phase. So the percent of G0/G1 phase increased with the decrease of S phase and cell proliferation rate and in vivo tumorigenic capacity decreased obviously. Our work would help shed light on the self-renewal and malignant growth of cancer cells.