[Establishment of breast cancer MDA-MB-231 cell line stably over-expressing human TOX high mobility group box family member 3].

Objective: To construct the lentiviral expression vector of human TOX high mobility group box family member 3 (TOX3) gene and the MDA-MB-231 cell line which stably over-expresses TOX3 gene.
Methods: TOX3 gene was synthesized by the gene synthesis method and amplified by PCR, and then cloned into pLVEF-1a/GFP-Puro vector to construct pLVEF-1a/GFP-Puro-TOX3 lentiviral vector. After restriction enzyme analysis and sequence identification, the lentiviral vector was packaged and the titer was detected. The human breast cancer MDA-MB-231 cells were transfected with the recombinant lentiviral vector and cultured selectively by puromycin to acquire stably transfected cells. MDA-MB-231 cells which expressed GFP were observed by fluorescence microcopy. And the expression levels of TOX3 mRNA and protein in transfected MDA-MB-231 cells were detected by real-time quantitative PCR(qRT-PCR) and Western blotting, respectively.
Results: Restriction enzyme digestion and sequence analysis demonstrated that the lentiviral expression vectors of pLVEF-1a/GFP-Puro and pLVEF-1a/GFP-Puro-TOX3 were successfully constructed, and the viral titers were respectively 2×10(8) TU/mL and 1×10(8) TU/mL after lentiviral packaging. And after being transfected, more than 95% cells expressed GFP under a fluorescence microscope. The results of qRT-PCR and Western blotting showed that, when compared with the MDA-MB-231-NC negative control group, the expression of TOX3 mRNA and protein significantly increased in the MDA-MB-231-TOX3 group.
Conclusion: The study successfully constructed lentiviral expression vector of TOX3 gene and obtained MDA-MB-231 cell line stably over-expressing TOX3 gene by transfection with the recombinant vector.