Objective   To explore the influence of RNAi-mediated hypoxia-inducible factor 1α (HIF-1α) silencing on the growth and metastasis of colon cancer in nude mice.    Methods   A total of 30 6-week-old female nude mice were randomly divided into normal saline group (NS group)

negative plasmid group and RNA interference group after injected with SW48

0 subcutaneously to form a colon carcinoma. shRNA-HIF-1α vector was constructed and injected (50 μg/time

once per 2 d

for 7 times) into the tumor mass of nude mice of RNA interference group to induce RNAi. Normal saline or blank vector was injected into the corresponding nude mice. The changes of HIF-1α were detected with RT-PCR and Western blot analysis. The size of tumors

metastasis rate and the positive rate of lymphnode were compared among different groups.    Results   In 15 d after RNAi vector injection

the tumor volume of RNAi group [(273.9±14.7) mm

3

]

was much smaller than those of NS group [(1 845.5±91.2) mm

3

]

and negative plasmid group [(1 842.7±115.7) mm

3

]

(P0.05). Lymph node metastasis rate in RNAi group (40%

4/10) was lower than those of NS group (100%

10/10) and negative plasmid group (100%

10/10)(Chi square=5.952

P=0.015). The lymph node positive rate in experimental group (35.7%

5/14) was significantly lower than those of NS group (77.3%

17/22) and negative plasmid group (65.2%

15/23)(Chi square=6.420

P=0.040). The mRNA level of HIF-1α and its protein expression of RNAi group also reduced obviously (P0.05).     Conclusion   The expression of HIF-1α

tumor sizes

metastasis rate and the positive rate of lymphnode in nude mouse have been obviously inhibited by pshRNA-HIF-1α

which may be used as a target for gene therapy.