ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of suppression of CCL5 ligand gene on the proliferation of human breast cancer cells.</p><p><b>METHODS</b>A lentiviral vector carrying a short interfering RNA (siRNA) targeting CCL5 was transfected into human breast cancer cell line MCF-7 and MDA-MB-231 cells. The expression of CCL5 mRNA in the cells was detected by real-time PCR. The proliferation of MCF-7 and MDA-MB-231 cells was assessed by MTT assay and FACS assay, and the colony formation ability of both cell lines were measured, respectively.</p><p><b>RESULTS</b>Real time PCR showed a good knockdown effect of CCL5 in both cell-lines. Colony-forming assay showed that the ability of colony formation of MCF-7/CCL5-siRNA and MDA-MB-231/CCL5-siRNA was decreased markedly. The colony number of MCF-7/CCL5-siRNA group was (0.34 ± 0.08), significantly lower than 0.81 ± 0.12 in the MCF-7/CCL5-N group and 0.92 ± 0.12 in the MCF-7 group (P < 0.05). The colony number of MDA-MB-231/CCL5-siRNA group was 0.33 ± 0.10, significantly lower than 0.97 ± 0.09 in the MDA-MB-231/CCL5-N group and 1.04 ± 0.07 in the MDA-MB-231 group (P < 0.05). However, MTT assay revealed that the proliferation of MCF-7/CCL5-siRNA cells was not significantly different from that of MCF-7/CCL5-N or MCF-7 cells, respectively (P > 0.05), and the same result was found in MDA-MB-231 cells. FACS assay showed that the proliferation index (PI) of groups MCF-7/CCL5-siRNA, MCF-7/CCL5-N and MCF-7 were 0.48 ± 0.03, 0.43 ± 0.01 and 0.45 ± 0.02. The PI of groups MDA-MB-231/CCL5-siRNA, MDA-MB-231/CCL5-N and MDA-MB-231 cells were 0.48 ± 0.02, 0.44 ± 0.05 and 0.47 ± 0.02. There was no statistical difference among them (P > 0.05).</p><p><b>CONCLUSION</b>The down-regulation of CCL5 gene in human breast cancer cells may significantly suppress their colony formation ability, rather than affecting their population doubling time to some extent.</p>