Objective  To investigate the potential effect of 4-amino-pynidine (4-AP) on human cervical carcinoma cell line HeLa to

252

Cf neutron ray.   Methods  HeLa cells were treated with 4-AP(0

1

5

10

20 mmol/L

respectively) and then exposed to 0.67 Gy

252

Cf neutron ray. The effect of 4-AP on proliferation of HeLa cells was assessed by MTT assay. Cell apoptosis were detected by flow cytometry. Reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were used to investigate the levels of HIF-1α mRNA and protein of HeLa cells treated with 4-AP (0

20 mmol/L) and 0.67 Gy

252

Cf neutron ray.   Results  After HeLa cells treated with 0

1

5

10

20 mmol/L 4-AP were exposed to 0.67 Gy

252

Cf neutron ray for 48 h

their inhibitory rate was 0， (38.81 ±3.45)%， (46.63±3.88)%， (63.58±6.19)%， (77.51±8.87)%， and their apoptotic rate was (3.15±0.85)%， (8.01±1.19)%， (16.00±1.58)%， (47.20±3.18)%， (62.56±4.27)%

respectively

suggesting 4-AP may inhibit the proliferation of HeLa cells and induce their apoptosis in a dose-dependent manner (P0.05). Of HeLa cells treated with 0 mmol/L 4-AP

the optical density ratio of HIF-1α mRNA/β-actin was (0.423±0.116)

(0.464±0.111)

(0.487±0.121)

(0.415±0.099) after 24-

48- and 72-hour exposure to 0.67 Gy

252

Cf neutron ray

while the optical density ratio of HIF-1α protein/β-actin was (0.723±0.116)

(0.664±0.111)

(0.617±0.121)

(0.515±0.099) (both P0.05). However

after treated with 20 mmol/L 4-AP and exposed to 0.67 Gy

252

Cf neutron ray for 24

48 and 72 h

the optical density ratio of HIF-1α mRNA/β-actin of HeLa cells was (0.401±0.121)， (0.364±0.142)， (0.257±0.137)， (0.165±0.099)

while the optical density ratio of HIF-1α protain/β-actin were (0.879±0.117)

(0.645±0.115)

(0.312±0.114)

(0.130±0.118)

showing that the levels of HIF-1α mRNA and protein both declined (P0.01).   Conclusion  To HeLa cells exposed to

252

Cf neut

ron ray

potassium channel blocker (4-AP) pretreatment inhibits their HIF-1α expression and their proliferation and promote their apoptosis. The potassium channel blocker (4-AP) significantly enhances the sensitivity of HeLa cells to neutron radiotherapy.