Objective    To investigate the potential effect of hypoxia on adhersion and invasion of human cervical carcinoma cells HeLa.     Methods    Reverse transcription-polymerase chain reaction (RT-PCR) was used to investigate the level of HIF-1α mRNA and E-cadherin mRNA of HeLa cells cultured under normoxia

5%O

2

3%O

2

1%O

2

. The invasiveness of HeLa cells was investigated by transwell chamber assay.     Results    Under the condition of normoxia

5%O

2

3%O

2

and 1%O

2

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

(0.764±0.111)

(1.687±0.126) and (0.215±0.099)

showing that the level of HIF-1α mRNA had a tendency of first inceasing and then decreasing with the decreasing oxygen content. The optical density ratio of E-cadherin/β-actin was (1.045±0.171)

(0.719±0.114)

(0.386±0.105) and (0.157±0.063)

showing a decreasing tendency with the decreasing of oxygen content. The invasiveness of HeLa cells was (112.5±20.7)

(254.3±27.5)

(333.6±45.2) and (124.5±24.6)

showing that the invasiveness of HeLa cells had a tendency of first inceasing and then decreasing with the decreasing oxygen content.     Conclusion    Moderate hypoxia up-regulates the mRNA levels of HIF-1α

and down-regulates the mRNA levels of E-cadherin

and enhances the tumor invasiveness. The possible mechanism is the increasing mRNA levels of HIF-1α.