The Role And Significance Of The Expression Of TGFA In Breast Cancer Bone Metastasis Cells

【Objective】To investigate the gene expression differences of breast cancer cells between before and after the bone metastasis. To explore the function of the differentially expressed genes in specific breast cancer bone metastasis.【Methods】①NOD/SCID female mice were selected to establish the animal model of human bone metastasis of breast cancer.②Metastatic cells were isolated, cultured and determined by chromosome preparation technique.③cDNA microarrays and RT-qPCR were used to screen the differentially expressed genes.④The RNA interference was used to silence the expression of the differentially expressed genes.⑤The gene expression differences of breast cancer cells between before and after RNAi treated were detected by RT-qPCR and Western Blot. The biological changes of the metastatic cells were measured by Transwell test in vitro and animal model in vivo.⑥All the data were analyzed by SPSS software. A value <0.05 was considered statistical significant.【Result】①The breast cancer cells had a higher predilection to metastasize to human transplanted bone rather than mice transplanted bone (50% vs 28%,P<0.05).②The chromosome mode of the metastatic cells which compare with the original cells was increased (n=68 vs n=66).③After the screening of cDNA microarrays analysis we found the expression of 3474 genes was up-regulated and that of 2894 genes was down-regulated. And we found that TGFA gene may play an important role in the metastasis to bone of breast cancer cell after a verification of RT-qPCR test.④A new cancer cell line was established from the bone metastatic cell line which was suppressed the expression of TGFA gene by an RNAi sequence. TGFA gene was down-regulated expression in the TGFA suppressed cells, there was a significantly decrease compared with the bone metastatic cells in TGFA mRNA and protein levels (P<0.05), and the invasive capacity in vitro was reduced too (P<0.05). In vivo study showed that the bone metastatic cells had a higher tumor formation rate of mice compared with the original cancer cells (80% vs 40%, P<0.05), and the TGFA suppressed cells had a lower rate compared with the bone metastatic cells (20% vs 80%, P<0.05).【Conclusion】①The human bone metastatic model which was established from NOD/SCID mice was more effective to explore the mechanism of breast cancer bone metastasis than the traditional animal model.②Chromosome mutation might cause the changing of gene expression profiles.③TGFA plays a very important role in bone metastasis of breast cancer. The overexpressed of TGFA could improve its bone metastasis rate by enhance the invasive capacity and the specific targeted effect.