Targeting HMGB1 inhibits ovarian cancer growth and metastasis by lentivirus-mediated RNA interference

High-mobility group box 1 (HMGB1), a nuclear and extracellular protein, is implicated in the development and progression of some types of cancers. However, no information is available to date regarding the function of HMGB1 in ovarian cancer. In this study, we performed cDNA microarray analysis and identified HMGB1 as a gene dramatically elevated in the highly invasive subclone S1 compared with the low invasive subclone S21 derived from the same cell line SKOV3. Then lentivirus vector with HMGB1 shRNA was constructed and infected the highly invasive cell line S1, A1, and HO8910PM. Real-time RT-PCR, Western blot, and IHC results confirmed the down-regulation of HMGB1 expression by its shRNA was about 80-90% at both the mRNA and protein levels. Knockdown of HMGB1 significantly suppressed ovarian cancer cell proliferation and induced cell cycle arrest at the G1/G0 phase, which was accompanied by decreased expressions of cyclin D1 and PCNA. Furthermore, knockdown of HMGB1 induced ovarian cancer cell apoptosis, which was mediated by increased expression of Bax and decreased expression of Bcl-2. Finally, knockdown of HMGB1 significantly inhibited ovarian cancer cell invasion and metastasis, which was regulated by decreased expressions of MMP2 and MMP9. Serum HMGB1 levels in patients with epithelial ovarian cancer were significantly higher than that in patients with benign ovarian tumor and healthy controls. These results indicate that HMGB1 is a newly identified gene associated with ovarian cancer growth and metastasis. HMGB1 may serve as a new therapeutic target for the treatment of ovarian cancer in the future.