ABSTRACT
Objective To detect the selective inhibitory effects of irradiation plus adenovirusmediated horseradish peroxidase ( HRP)/indole-3-acetic acid (IAA) suicide gene system using tumorspecific and radio-inducible chimeric promoter on human hepatocellular carcinoma subcutaneously xenografted in nude mouse.MethodsRecombinant replicated-deficient adenovirus vector containing HRP gene and chimeric human telomerase reverse transcriptase (hTERT) promoter carrying 6 radioinducible CArG elements was constructed.A human subcutaneous transplanting hepatocellular carcinoma (MHCC97 cell line) model was treated with -γ-ray irradiation plus intra-tumor injections of adenoviral vector and intra-peritoneal injections of prodrug IAA.The change of tumor volume and tumor growth inhibiting rate,the survival time of nude mice,as well as histopathology of xenograft tumor and normal tissues were evaluated.Results Thirty one days after the treatment,the relative tumor volumes in the negative,adenovirus therapy,irradiation,and combination groups were 49.23 ± 4.55,27.71 :± 7.74,28.53 + 10.48 and 11.58 ± 3.23,respectively.There was a significantly statistical difference among them (F = 16.288,P ＜0.01 ).The inhibition effect in the combination group was strongest as compared with that in other groups,and its inhibition ratio was 76.5%.The survival period extended to 43 d in the combination group,which showed a significantly difference with that in the control group(x2 = 18.307 ,P ＜0.01 ).The area of tumors necrosis in the combination group was larger than that in the other groups,and the normal tissues showed no treatment-related toxic effect in all groups.However,multiple hepatocellular carcinoma metastases were observed in the liver in the control group,there were a few metastases in the monotherapy groups and no metastasis in the combination group.Conclusions Adenovirus-mediated suicide gene therapy plus radiotherapy dramatically could inhibit tumor growth and prolong median survival time.It might provide a promising therapeutic modality for hepatocellular carcinoma therapy.
ABSTRACT
The use of optimal regulatory sequences for simultaneous expression of the transgenes might play a significant role in engineering plants with increased disease and insect resistance.The plant expression vector pOMS-GUS,which contained the GUS gene under the control of a chimeric promoter based upon the mannopine synthase(mas)promoter and the octopine synthase(ocs)enhancer,was constructed.Used as control,another vector pMAS-GUS,carried the GUS gene driven by only the mas promoter.The two vectors were introduced into tobacco plants by Agrobacterium-mediated transformation.Fluorometric assays for GUS activity and reverse transcription-polymerase chain reaction(RT-PCR)analysis revealed that GUS gene expressed weakly with untreated transgenic tobacco while the level of GUS activity increased steadily after 1 h subjected to wounding.The expression of the mas and ocs/mas promoters was induced a further 1.8-fold and 5.7-fold,respectively.SA(1 mmol/L)or MJ(250 ?mol/L)treatment also caused a large induction of the ocs/mas chimeric promoter;And the application of SA in combination with MJ(1 mmol/LSA & 250 ?mol/L MJ)produced an additive effect that exceeded the wounding response.The results showed that the ocs/mas chimeric promoter is a strong inducible promoter that can be activated by various stresses.The chimeric promoter should have utility in development of disease and insect resistant transgenic crops.