The Feature of SALL4 and BMI-1 Expression in Placenta and Umbilical Cord Blood

Abstract 4800

The SALL4 is a newly discovered pluripotency stem cell factor involved in the self-renewing, hematopoietic stem cells (HSCs) and leukemic stem cells. Its important role in normal HSCs and leukemic stem cells is supported by its interactions with several key players, like BMI-1, a putative oncogene of the Polycomb group family, controlling specific target genes involved in development, cell differentiation, proliferation, and senescence. Little is known the expression feature of SALL4 and BMI-1 mRNA in placenta and umbilical cord blood (UCB). In this study, the mRNA expression level of SALL4 and BMI-1 in 10 cases placenta tissues and the mononuclear cells from the corresponding UCB (CBMCs) were measured by real-time PCR with SYBR Green I technique, β2-microglobulin gene (β2M) was used as an endogenous reference, mononuclear cells from 10 healthy adults peripheral blood (PBMCs) and 2 cases of adult thymic cells served as control. The result showed that the expression level of both SALL4 and BMI-1 in placenta (Median: 34.36 and 17.55 respectively) were significantly higher than those from CBMCs (Median: 11.3 and 2.07 respectively) (p=0.007, p=0.001) and PBMCs (Median: 0.64 and 0.03 respectively) (P<0.001, P<0.001). Moreover, both SALL4 and BMI-1 expression levels in CBMCs were significant higher than those from PBMCs (P=0.002, P=0.001). And the expression of SALL4 could be detected in thymic cells. Correlation analysis was performed among the relative expression levels of SALL4 and BMI-1. The results showed that significant positive correlation between the expression levels of SALL4 and BMI-1 was observed in placenta tissues and CBMCs, as well as in PBMCs (r_s=0.648, P=0.043, r_s=0.721, P=0.019, r_s=-0.697, P=0.025). In conclusions, the expression level of SALL4 and BMI-1 might be related to the numbers of hematopoietic stem cells, placenta tissues may be as an appropriate model for investigating gene regulation of SALL4 and BMI-1, while the significance of expression both genes in PBMCs and thymic cells is needed further investigation.