The Effect Of Mitochondrial Knockdown On Carcinogenic Process Of Radon Exposure To Human Bronchial Epithelial Cells

Objective: To explore the role of mitochondrial knockdown in the carcinogenicprocess of radon exposure to human bronchial epithelial cellsMethods:(1)The ρ-HBE cells were generated by treatment of ethidium bromide(EB) and verified by real-time PCR and mtDNA staining. The ρ-HBE and ρ+HBEcells were exposed to radon gas and cultured for several passages. The biologicalcharacteristics of the cells with radon exposure were measured, including ROS, ΔΨm,cell cycle and apoptosis.(2) Soft agar assay, plating efficiency assay, wound-healingassay and in vivo animal assay were used to detect the effects of mitochondrialknockdown on carcinogenic process of radon exposed cells.Results: Thirty days after the EB induction, the number of mitochondrial in ρ-HBE cells decreased77%of that in ρ+HBE cells. mtDNA deletions, mitochondrialmembrane damage and ΔΨm decrease were observed, suggesting successfulestablishement of the EB-treated ρ-HBE cells. Cell biological analysis showed anincrease in cellular ROS level and in ΔΨm in HBEρ+cells The G1and S phaseincreased, G2phase decreased in HBEρ+cells, but in contrast in HBEρ-cells. At Rn7both HBEρ+cell and HBEρ-cell showed increase in early apoptosis, late apoptosisand total apoptosis. At Rn12both HBEρ+cell and HBEρ-cell showed decreasedapoptosis. At Rn17both HBEρ+cell and HBEρ-cell showed increase in earlylate andtotal apoptosis.(2)With radon exposure, HBEρ+cells showed a higher soft agar andwound-healing growth than HBEρ+-cell, but lower in plating efficiency. InoculatedHBEρ+、HBEρ-、HBEρ+Rn15P55、HBEρ+Rn15P109、HBEρ+Rn20P55、HBEρ-Rn15P55cells were tramsferred subcutaneously to nude mice, only the HBEρ+Rn15P109cellswere able to induce tumor, suggesting a characteristic of malignant cells.Conclusions:1.Using the EB induction methord, a HBEρ-cell model with mtDNApartial knockout was successfully established. 2. By soft agar, plating efficiencyand wound-healing assay in vivo, the role ofmitochondria on carcinogenic effects of radon exposure was investegated, and theHBEρ+cells were found more volunable to be malignant transformation than theHBEρ-cells.