Abstract
The majority of colorectal cancers (CRCs) are hormone‑dependent. Thus, endocrine therapy has become an attractive strategy to treat CRC. The aim of the present study was to investigate the inhibitory effect of combined tamoxifen (TAM) plus β‑estradiol (E2) treatment on human DLD‑1 CRC cells. The human DLD‑1 CRC cell line was treated with different concentrations of TAM, β‑estradiol, or a combination of these two agents. Cell viability was assessed using an MTT assay, while apoptosis was detected using flow cytometry analysis. Alterations in the RNA and protein levels of the apoptosis‑associated factors cyclin D1 and survivin were measured in the treated DLD‑1 cells using semi‑quantitative polymerase chain reaction (sqPCR) and western blot analyses. Alterations in cellular migration ability were monitored using a Transwell migration assay. Treatment with TAM, β‑estradiol and TAM plus β‑estradiol inhibited DLD‑1 cell viability. The flow cytometry results revealed that these drugs promoted cell apoptosis, and the Transwell migration assay results indicated that the reduction in cell migration was greater in the TAM+E2 treatment group when compared with each treatment alone. sqPCR and western blot analysis results demonstrated that TAM, E2 and a combination of the two affected survivin expression based on the drug concentration and the treatment duration; however, they demonstrated no significant effect on cyclin D1 expression. In conclusion, treatment of DLD‑1 cells with TAM, β‑estradiol, or a combination of these two drugs, inhibited cell viability and migration, promoted cell apoptosis, and reduced the mRNA and protein expression levels of survivin in a dose‑ and time‑dependent manner. These results provide novel experimental basis for hormonal adjuvant therapy for the treatment of CRC.