The Reverse Effect Of Adenovirus-mediated Co-expression Of IL-24/PTEN On Acquired Resistance To Gefitinib And The Mechanism Of Acquired Resistance

Objectives: To investigate The reverse effect of adenovirus-mediated co-expression ofIL-24/PTEN on acquired resistance to gefitinib and thepossible mechanism of acquiredresistance.Methods:The recombinant adeno-viral vectors of Ad.RGD-IL-24, Ad.RGD-PTEN andAd.RGD-IL-24-PTEN were constructed, and then were transfered into QBI-293A cells.The combinant adenovirustiter were evaluated after they were amplified and purified. Thecell proliferation of each treated PC-9/GR cell group was detected by MTT assay. The cellcycle percentage was detected by flow cytometry analysis, and the tumor related factorswere detected by western blot. The expression levels of P-gp、LRP、IGF-1R in both PC-9and PC-9/GR cell lines were detected to determine the resistance mechanism of PC-9/GRcell line on gefitinib. The graft tumors from the PC-9/GR cell lines in nude mice wereestablished. The tumor growth was observed,and the growth curve was drawn.The tumorweight was recorded and the tumor growth inhibition rate was calculated.The expressionlevels of apoptosis-related cytokines and tumor angiogenesis factors were determined byimmunohistochemistry.Results:(1)The recombinant adeno-viral vectors expressing IL-24, PTENorIL-24/PTENwere constructed successfully.(2)The gefitinib tumor growth inhibition rates of PC-9/GR transfected by Therecombinant adeno-viral vectors increased significantly, all of which theAd.RGD-IL-24-PTEN transfected cells increased the most.(3) The IC50of gefitinib for the Ad.RGD-IL-24-PTEN transfected cells was obviouslylower than others, which suggested that the Ad.RGD-IL-24-PTEN vector made a bestreverse effect on the resistence. (4) Ad.RGD-IL-24-PTEN vector and gefitinib together could induce cell cycle G2/Marrest about55.13percent, very colsed to PC-9cell line.(5) Western-Bolt results indicated that, IL-24, PTEN or IL-24/PTEN couldup-regulate the apoptosis-related cytokine levels, among which IL-24/PTEN had the mostobviousregulation effect.(6) IGF-1R had a higher expression level in PC-9/GR than in PC-9cell line.(7) In the graft tumor assay, both the tumor growth inhibition rate and the regulatingefficiency in the IL-24/PTEN combined with combined with gefitinib group weresignificantly higher than in the other groups.Conclusions:(1) Ad.RGD-IL-24-PTEN can effectively mediate the expression of PTENand IL-24.(2) It is suggested that adenovirus-mediated co-expression of IL-24and PTENhas a reverse effect on the resistence of human lung adenocarcinoma PC-9/GR cell line togefitinib in both vivo and vitro tests. IGF-1R may be concerned with the molecularmechanism.(3) The reverse effect of adenovirus-mediated co-expression of IL-24/PTEN onwas better than any other single gene.