| Background: Hepatocellular carcinoma(HCC) is one of the most common malignant tumor of the digestive system. Chemotherapy is the important factor in the combined therapy of this neoplasma. But multidrug resistance leads to chemotherapy failure often. The Resistance Reversal agents can overcome the multidrug resistance, but most of them can not be used for clinical cosmically because their Side effects. It is reported that Cell signaling pathway inhibitors can also overcome the multidrug resistance .Sorafenib is a novel and oral multi-target antineoplastic. It refrains tumor cell proliferation by inhibiting ERK signaling pathway.Objective: To explore whether Sorafenib can reverse the resistance to Gemcitabine(GEM)of human hepatocellular carcinoma HepG2/GEM cell line in vitro and its potential mechanism.Methods: To examine the sensitivity of human hepatocellular carcinoma HepG2 cell line to GEM, CPT-11, TAX, EPI-ADM and OXA. Induced the human hepatocellular carcinoma cell line HepG2 to be resistant to GEM. Method MTT assay was used to test the inhibition rate of the Sorafenib to HepG2 and HepG2/GEM cell lines and the chemosensitivity to chemotherapeutics in sorafenib–treated HepG2 and HepG2/GEM cell lines. The expression of MDR/P-gp,ERK,VEGFR2 was measured by RT-PCR and Western blot.Results:1.the Inhibition rates of GEM,CPT-11,TAX, EPI-ADM and OXA in 1×PPC to the HepG2 in 72 h is 63.98%, 58.02%, 55.82%, 64.42%, 48.53%. 2. Use high dose pulse treatment selection to obtain the GEM resistant cell line named HepG2/GEM cells. The IC50 value of GEM to HepG2/GEM and HepG2 cells in 72h was 12.10ug/ml and 1.04ug/ml respectively. The final level of resistace to GEM of HepG2/GEM was 11.63-fold compared to parental HepG2 cells.3. Sorafenib inhibited HepG2 and HepG2/GEM cells hardly in 1μg/ml, and the inhibition rate increased with the increasing concentration of drug in higher dose. The IC50 value of Sorafenib to HepG2/GEM and HepG2 cells in 72h was 4.84ug/ml and 4.38ug/ml respectively.4. The IC50 value of GEM to HepG2/GEM was decreased obviously after the Sorafenib treatment in 1μg/ml compared to HepG2/GEM cells. The final reversal level of resistace to GEM of HepG2/GEM was 3.08-fold. The IC50 value of GEM to HepG2 was not change significantly after the Sorafenib treatment in 1μg/ml compared to HepG2 cells.5. RT-PCR results showed: the expression of MDR-1, ERK, VEGFR2 in HepG2 cells were weaker than in HepG2/GEM cells, which changed little after Sorafenib treatment. But in HepG2/GEM cells, the expression decreased significantly after treatment with 1μg/ml Sorafenib for 72 hours, which were still higher than in HepG2 cells.6. Western blot results showed: the expression of P-gp and VEGFR-2 in HepG2 cells were weaker than in HepG2/GEM cells, which changed little after Sorafenib treatment. But in HepG2/GEM cells, the expression decreased significantly after treatment with 1μg/ml Sorafenib for 72 hours, which were still higher than in HepG2 cells.Conclusion:1. GEM, CPT-11, TAX, EPI-ADM are moderately sensitive to human hepatocellular carcinoma HepG2 cells and OXA is Low sensitive in vitro.2. The HepG2 cells could be induced in vitro to be the acquired GEM- resistant lines.3. There is no Cross-resistance between GEM and sofafenib.4. Sofafenib can reverse drug- resistance to GEM of human hepatoma carcinoma cells, whith is associated with decreasing the expression of MD- R-1/P-gp, VEGFR-2 and ERK1/2.
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