Objective    To screen and identify the efficient heparanase (Hpa) RNAi sequence.     Methods    We chose three candidate targets of Hpa RNAi through online software and designed a set of independent sequence as negative control group. The three interference fragments and independent sequence were cloned into pGenesile-1 expression vector by gene recombination technique. The recombinant vectors were then transfected into HepG2 liver cancer cell line. After screening by G418

the expression of heparanase in the selected clones was detected by Western blot

and its mRNA expression level by RT-PCR.     Results    The three interference sequences designed with online tool respectively was Hpa/RNAi-1: GGCTATCTCTTCTGTTCAA; Hpa/RNAi-2: TCCTGTCCGTCACCATTGA; Hpa/RNAi-3: CTCAGTTGCTCCTGGACTA and negative control Hpa/RNAi-N:CTACCGTTGTATAGGTGT; The three interference sequence were cloned into pGenesil-1 vector

respectively. Sequencing analysis confirmed their correctness. Positive clones formed after their stable transfection into HepG2 and G418 screening. Compared with untransfected HepG2 and negative control

Western blot analysis showed heparanase protein in interference sequence transfected HepG2 was significantly down-regulated. Hpa/RNAi-1 and Hpa/RNAi-3 showed better inhibition effect

with their inhibition efficiency to 57% and 71% respectively; RT-PCR result proved the sequence of Hpa/RNAi-1 and Hpa/RNAi-3 could effectively down-regulate heparanase on mRNA level.     Conclusion    We successfully screen and identify the efficient heparanase RNAi sequence.