The Research Of The Synergistic Effect Of Tamoxifen And Ad-p53on Breast Cancer Treatments

Objectivep53is a tumor suppressor gene, the mutation and inactivation of which is closely relatedwith the occurrence and progression of tumor. Recent studies suggest that the functionof the mutated and inactivated gene can be restored by introducing normal functionspressor gene into the tumor cell. Carried by adenovirus, recombinant human p53adenovirus (Ad-p53) can restore the function of p53gene by transferring wild-type p53gene into tumor cell. Tamoxifen (Tamoxifen, TAM), one of selective estrogen receptormodulators (SERMs), is widely used in the treatment of estrogen receptor-positivebreast cancer. We observed and analyzed the morphological change of breast cancer cellafter being infected by Ad-p53gene, as well as the proliferation inhibition ratio of thebreast cancer cell, the expression level of p53protein and the apoptosis of breast cancercell. We discussed the synergistic effect of Ad-p53together with tamoxifen, aiming toprovide a theoretical basis for both clinic and basic research in the field of breast cancertreatment.Methods1. The morphological change and proliferation of MCF-7cells were compared by aninverted microscopy after MCF-7cells being effected with Ad-p53(50MOI) aloneand TAM together with Ad-p53.2. The cell proliferation inhibition ratio of MCF-7were compared after being effectedby Ad-p53(50MOI) alone, TAM (5μmol/l), and TAM with Ad-p53.3. The expression of p53protein of MCF-7were compared by Western blot analysis72 hours after being effected by Ad-p53(50MOI), TAM (5μmol/l), and TAM withAd-p53.4. The cell apoptosis ratio of MCF-7cells were compared by Flow cytometry72hoursafter being effected by Ad-p53(50MOI), TAM (5μmol/l), or TAM with Ad-p53.Results1.Poor homogeneity and slow proliferation of the cytoplasm were observed by aninverted microscope after MCF-7cells being treated with Ad-p53. While in theTAM and Ad-p53group, shrinkage and the cell suspension occurred.2. MTS revealed that MCF-7cell proliferation inhibition rate24-72hours after beingtreated by Ad-p53was7.16%±0.39%,25.28%±0.95%,36.86%±0.82%and62.12%±1.01%. In the TAM and Ad-p53group, the result is11.76%±0.86%,39.92%±0.47%,56.92%±0.68%and69.49%±0.56%.3. The expression level of p53protein was higher usingAd-p53together with TAMthen using TAM alone, but not higher than using Ad-p53alone.4. Flow cytometry revealed that after being effected for72hours, the cell apoptosisratio was34.7%in the TAM with Ad-p53group,17.5%in the tamoxifen group, and21.9%in the Ad-p53group.Conclusions1. Significant morphological change in MCF-7cells were observed by an invertedmicroscope when infected by Ad-p53gene. An extremely low proliferation andearly appearance of morphological change occurred when using TAM together withAd-p53.2. MTS assay showed that cell proliferation inhibition ratio was higher using TAMtogether with Ad-p53, compared with using them separately. 3. Ad-p53could induce the expression of p53protein in breast cancer MCF-7cells.While it could not be increased obviously by using Ad-p53together withtamoxifen.4. Ad-p53could induce apoptosis in MCF-7cells, while tamoxifen has a synergisticeffect on Ad-p53-induced apoptosis.