Abstract 15P
Background
Tamoxifen treatment revolutionized the management of estrogen receptor (ER) positive breast cancers, however drug resistance compromises its clinical efficacy. We here investigate effect of VEGFR signal pathway inhibitor apatinib on tamoxifen resistant breast cancer cell line and its possible mechanism.
Methods
The morphological differences between parent breast cancer cell line MCF7 and tamoxifen resistant cell line LCC2 were observed. CCK-8 assay was used to determine the proliferation inhibition rate of MCF7 and LCC2 cells treated with different concentrations of 4-hydroxy-tamoxifen (4OHT), and proliferation inhibition rate of LCC2 cells treated with different concentrations of apatinib or 4OHT combined with 10 μM apatinib for 48 hours. The apoptosis rate of LCC2 cells was detected by flow cytometry (FCM). Western blotting was used to detect the expression of ERα, PI3K, Akt and p-Akt pathway proteins in MCF7 and LCC2 cells, and the changes of Bcl-2, Bax apoptosis protein and ER α, PI3K, Akt and p-Akt protein expression in LCC2 cells treated with three different treatments.
Results
The morphology of MCF7 cells is slightly different from LCC2 cells: LCC2 cells are fusiform or triangular with a slightly shorter long axis. CCK-8 assay showed that the inhibition effect on LCC2 cells with the same concentration of tamoxifen was less than that on MCF7 cells. And LCC2 cell inhibition rate increased with the increase of tamoxifen concentration after were treated with 10 μ M Apatinib for 48 hours, which showed a significant synergistic enhancement between them (P < 0.05). FCM showed that the apoptosis rate in the experimental group was higher than control group (P < 0.05), and combination group was higher than tamoxifen group (P < 0.01). Western blotting showed that the expression of ER α, PI3K, Akt and p-Akt protein in the LCC2 was higher than MCF7 (P < 0.05). And in the combination group was less than tamoxifen group, while the expression of Bax protein was increased (P < 0.01).
Conclusions
Apatinib can enhance the re-sensitivity of resistant cells to tamoxifen, which may be related to the up-regulation of Bax protein and down-regulation of Bcl-2 protein and the expression of estrogen receptor pathway proteins ERα, PI3K, Akt and p-Akt.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Qingxia Li.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.