Objective      To inhibit the expression of stromal interaction molecule 1 (STIM1) gene of pulmonary artery smooth muscle cells (PASMCs) through RNA interference

and to explore the proliferation ch

ange of PASMCs under hypoxia condition after gene silencing.      Methods     

In vitro

cultured PASMCs were divided into a blank control group

a negative control siRNA group (SiNT) and a positive siRNA group (SiSTIM1) that were cultured in hypoxia condition (3% O

2

) for 24 h

as well as a normal group that was cultured in normal O

2

condition (21% O

2

) for 24 h. Western blotting

MTT assay and [

3

H

]

-TdR incorporation assay

and flow cytometry were employed to test STIM1 gene expression

cell proliferation

and cell cycle of PASMCs

respectively.      Results     Western blotting results showed that the relative grey value of STIM1 protein in the SiSTIM1 group (0.355±0.008) was remarkably lower than that in the control group (0.624±0.017) and the SiNT group (0.618±0.021) (

P

<

0.05). MTT assay and [

3

H

]

-TdR incorporation assay exhibited that

after 24 h hypoxic culture

the PASMCs in the blank control group and the SiNT group proliferated significantly as compared with those in the normal group (

P

<

0.05) and the SiSTIM1 group (

P

<

0.05). Flow cytometry results discovered that

after hypoxic culture for 24 h

the percentages of PASMCs in G

0

/G

1

phase in the blank control group and the SiNT group were remarkably lower than those in the normal group (

P<

0.05) and the SiSTIM1 group (

P

<

0.05).     Conclusion      RNA interference-mediated STIM1 gene silencing can significantly inhibit the proliferation of PASMCs under hypoxia.