Influence Of Different Hypoxic Time On Abilities Of Hepatocarcinom Cells And Normal Liver Cells To Endure Hypoxia

Background and Objectives:Hepatocellular carcinoma(HCC) is one of the most common malignant tumors worldwide.With studies on clinic became wider and deeper during the recent years,there has been a great progress in surgical and medical therapeutic tools of HCC.Transcatheter arterial embolization(TAE) and hepatic artery ligation(HAL) are effective therapeutic methods of HCC.After arterial blood flow being interruptted,tumor cell growth will be inhibitted and tumor cell necrosis occurred.But the long term prognosis is not yet satisfactory.HCC will grow rapidly again after a short period time.There are two main reasons:1.HCC gain hyperxia through arterial collateral circulation and neovascularization after the arterial flow of HCC was blocked.2.HCC has high ability to endure hypoxia.Hepatoma carcinoma cell transcriptional activated target gene which contain a hypoxia response element through hypoxia-inducible factor 1(HIF-1) and course a series of response to hypoxia.Such gene products were more in tumor cells than in normal tissue cells.HIF-1 can strengthen glycolytic pathway of tumor cells and make tumor cells adapt hypoxic condition.Traditional theory indicated that tumor cells had more survival ability under hypoxic condition than normal tissue cells.The biological character that tumor cells have higher capability to endure hypoxia has been regarded as a central factor for tumor development,aggressiveness and metastasis.The theory that tumor cells have more ability to endure hypoxia than normal tissue cells has been accredited generally.But we found that the hypoxic time affected the ability of tumor to endure hypoxia.The ability of HCC to endure hypoxia will decrease with extended hypoxic time and become lower than nomal tissue cells.In the present study,we investigated the relationship between hypoxic time and the ability of HCC and normal liver cells to endure hypoxia through long-term cultivation under low oxygen condition.Our purpose was to evaluate the abilities of HCC to endure hypoxia objectively without the effect of arterial collateral circulation and neovascularization.Methods:Port vein provide oxygen to HCC in vivo after arterial blood flow was blocked,so we chose two different oxygen concentration(10%O₂+ 5%CO₂ + 85%N₂ and 12%O₂ + 5%CO₂+83%N₂) correspondence to port vein'.Hep3B cells and Chang cells were subjected to either contral(room air-5%CO₂) or hypoxic conditions(10%O₂ + 5%CO₂+ 85 %N₂ and 12%O₂+5%CO₂+83%N₂)for 72h and cell inhibition ration was detected by MTT.Inhibition ration%=(1-ODt/ODs)×100%.Data were present as X±S.Statistical analyses were performed using the Repeated Measureds Analysis of Variance with SAS 9.1.3 software package.A P value less than 0.05 was considered statistically significant.Results:1.Under normoxia condition,Hep3B and Chang cells grew stably,Hep3B had more powerful reproductive activity than Chang cells(P＜0.05).Under hypoxia condition,both Hep 3B and Chang cell growth were inhibited.2.Under hypoxia environment,inhibition ratio of Hep3B cells and Chang cells increased stably with the hypoxic time extension.At the early stage(24h)of hypoxia(10%O₂+5%CO₂+85%N₂),inhibition ratio of Hep3B cells was lower than Chang cells'(P＜0.05).But with the hypoxic time being extended(72h),the inhibition ration of Hep3B cells was higher than Chang cells(P＜0.05).Under hypoxic environment (12%O₂+5%CO₂+83%N₂),the inhibition ratio of Hep3B cells was higher than Chang cells'with the hypoxic time being extended(48h and 72h) too.Conclusion:The ability of HCC to endure hypoxia had correlation with hypoxic time.At early stage of hypoxia;HCC had powerful ability to endure hypoxia.But the ability decreased siganificantly and became lower than Chang cells in long term hypoxic cultures.HCC in vitro model exclude the effection of arterial collateral circulation and neovascularization which can provide hyperxia to HCC in vivo.These results suggest that arterial collateral circulation and neovascularization may be the major factor of generation and recurring of HCC in vivo.