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[Screening and structure analysis of nucleic acid aptamers binding to surface of CD33(+)/CD34(+) cells from patients with acute myeloid leukemia subtype M₂].

A little is known about the specific marker on the surface of acute leukemia cells, leading to the lack of the specific diagnosis method for acute leukemia. Therefore, in this study, cell-systematic evolution of ligands by exponential enrichment (cSELEX) was performed to screen the aptamers binding to CD33(+)/CD34(+) cells from the patients with acute myeloblastic leukemia (AML) of M(2) subtype (AML-M₂) so as to provide the basis for finding the specific marker on the surface of AML-M(2) CD33(+)/CD34(+) cells. Firstly, AML-M₂ CD33(+)/CD34(+) cells were sorted and used as targeted cells, and normal CD33(+)/CD34(+)cells were used as counter-targeted cells; the aptamers binding to CD33(+)/CD34(+) cells from patients with AML-M₂ were screened from the single strand deoxyribonucleic acid (ssDNA) library by cSELEX. Subsequently, each aptamer structure was analyzed after cloning and sequencing. The results indicated that after 13 round of screenings, the enrichment of aptamers in the ssDNA library was ranged from 0.7% to 52.9%, and reached steady state at 13th round screening. Sequence analysis for 30 aptamers showed that most of the aptamers born one of the three conserved sequences of CCCCT, CTCTC, and CTCAC. Secondary structure analysis indicated that three different secondary structures existed in these aptamers. It is concluded that the aptamers binding to the AML-M(2) CD33(+)/CD34(+) cells are successfully screened, which lay the basis for further looking for the specific marker on the surface of AML-M₂ CD33(+)/CD34(+) cells, and the molecular diagnosis of the AML-M₂ leukemia.