OBJECTIVETo evaluate the effects of hypoxia on the expression of heparanase and the invasiveness of Hep-2 laryngeal carcinoma cell line.

METHODSHep-2 cells were incubated at either normoxia (37 degrees C, 5% CO2, 20% O2) or hypoxia (37 degrees C, 5% CO2, 2% O2) condition for 6 h,12 h,24 h,36 h. Flow cytometry was used to detect the protein expression of heparanase under different hypoxia conditions. Fluorescence Index represents the relative content of heparanase protein. Cell invasiveness was measured by matrigel invasion assay.

RESULTSCompared with normoxia group, the heparanase protein expression level in 6 h hypoxia group was increased (P <0.05) and the heparanase protein expression levels in other hypoxia groups were significantly increased (P < 0.01). The heparanase protein expression level was increased (P < 0.05) among 6 h, 12 h, 24 h hypoxia groups; Compared with normoxia group, there was no significant change in the invasion cells at 6 h (P > 0.05) in hypoxia group; whereas the level of cell invasion was significantly increased in 12 h(P < 0.05), 24 h and 36 h groups (P < 0.01). During 6 to approximately 36 h hypoxia period, the increase of hypoxia-induced invasiveness in Hep-2 cell line show time-dependent manner. Meanwhile, there was a positive correlation between the expression of HPSE and the invasiveness of Hep-2 cells.

CONCLUSIONInvasion of Hep-2 cells in hypoxia condition correlates with heparanase level. Hypoxia plays an important role in the augmentation of the heparanase expression and the invasiveness of human laryngeal carcinomas.