Somatostatin enhances the antineoplastic effects of tamoxifen on breast carcinoma in vitro
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To study the antineoplastic effects of tamoxifen (TAM) in combination with a somatostatin analogue (octreotide, OCT) on breast cancer.
Estrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-435S) human breast carcinoma cell lines were treated with TAM or OCT, or combination of both agentsin vitro. Cell proliferation was evaluated by MTT assay, distribution of cell cycle and rate of apoptosis were determined by flow cytometry.
The inhibitory effect of OCT or TAM on proliferation of MCF-7 cells was associated with cell arrest in G0/G1 phase and induction of apoptosis. The inhibitory effect on proliferation of MCF-7 cells was enhanced when treatment of TAM combined with OCT. The increased rate of apoptosis induced by combination of TAM and OCT was much higher than use of either TAM or OCT alone. TAM or OCT also had weak inhibitory effect on MDA-MB-435S cell. The cells were arrested at S phase by TAM and at G0/G1 phase by OCT, but the induction of apoptosis was not identified. However, the rate of apoptosis was 22.7% if combined treatment of TAM and OCT applied.
TAM and OCT can synergistically inhibit proliferation and induce apoptosis of ER-positive and ER-negative breast cancer cells. The synergism of TAM and OCT may be of interest in the clinical treatment of breast carcinoma.
Key wordsbreast neoplasms octreotide tamoxifen
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