ABSTRACT
To explore the effects of obatoclax(OBX) combined with gemcitabine(GEM) on breast cancer cells MCF-7 and BT-20 cell activity, migration, invasion and apoptosis under hypoxia condition. Breast cancer cells MCF-7 and BT-20 were divided into normal group, hypoxia group, GEM group, OBX+GEM group. Normal group: Cells were cultured at 37℃, 5% CO for 24 h and 48 h; Hypoxia group: Cells were cultured at 37℃, 1% O, 5% CO, 94% N for 24 h and 48 h; GEM group: Cells were cultured at 37℃, 1% O, 5% CO, 94% N, adding 10 μmol/L GEM for 24 h and 48 h; OBX + GEM group: Cells were cultured at 37℃, 1% O, 5% CO, 94% N, adding 10 μmol/L GEM and 50 nmol/L OBX for 24 h and 48 h. Western blot method was used to detect the expressions of HIF-1α in MCF-7 and BT-20 cells under normal oxygen and hypoxia condition. CCK-8 method was used to detect cancer cell activity, each group was provided with 15 compound holes. Scratch experiment was used to detect cells migration ability, each group was provided with 6 compound holes. Western blot method was used to detect the expressions of vimentin, E-Cadherin and p53 protein in cells of each group. Under hypoxia condition, the expression of HIF-1α in MCF-7 and BT-20 cells was much higher than that under normal oxygen(P＜0.05). Compared with hypoxia group, GEM could reduce MCF-7 and BT-20 cells migration ability(P＜0.01)and cell activity(P＜0.05), while decrease the expression of vimentin protein(P＜0.01)and promote the expressions of E-Cadherin (P＜0.01)and p53 protein(P＜0.01) in tumor cells under hypoxia condition. In OBX combined with GEM group, the cell activity and the migration ability of MCF-7 and BT-20 were reduced significantly(P＜0.01). The expression of vimentin in cells was further reduced(P＜0.01). The expressions of E-Cadherin(P＜0.01)and p53(P＜0.01) protein were increased significantly compared with GEM group. Under hypoxia condition, OBX combined with a low-dose of GEM can significantly inhibit the growth, migration and invasion of breast cancer cells, and enhance the pro-apoptotic effect of GEM, but the specific mechanism needs further study.
ABSTRACT
OBJECTIVE@#To explore whether bortezomib and a Bcl-2 inhibitor exhibit synergistic anti-tumor effect in human acute T lymphoblastic leukemia cells.@*METHODS@#MTT assay was used to determine the cytotoxicity of bortezomib in the absence or presence of Bcl-2 inhibitors (obatoclax, AT-101 and ABT-199) in Jurkat cells. The effects of drug treatment on the expression of Bcl-2 family proteins, LC3B, p62, ubiquitin, BiP/Grp78, p-JNK, p-p38 and CHOP proteins were examined by Western blotting. Flow cytometry was used to determine the effects of bortezomib and Bcl-2 inhibitors (obatoclax, AT-101 and ABT-199) on cell apoptosis. Quantitative real-time PCR was used to measure the mRNA expression levels of the key regulatory factors of unfolded protein reaction (UPR). A zebrafish xenograft model was used to study the anti-tumor effect of bortezomib, obatoclax and their combination in vivo.@*RESULTS@#Bortezomib or Bcl-2 inhibitors alone inhibited the cell viability of Jurkat cells, but only obatoclax and bortezomib showed synergistic cytotoxicity and pro-apoptotic effect. Obatoclax, rather than AT-101 and ABT- 199, blocked autophagic flux in the cells evidenced by concomitant accumulation of LC3B-Ⅱ and p62. Both bortezomib and obatoclax alone caused accumulation of polyubiquinated proteins, and their combination showed a synergistic effect, which was consistent with their synergistic cytotoxicity. The dual blockade of proteasome and autophagy by the combination of bortezomib and obatoclax triggered unfolded protein response followed by cell apoptosis. Preventing UPS dysfunction by tauroursodeoxycholic acid (TUDCA) significantly attenuated the cytotoxicity and pro-apoptotic effect of bortezomib in combination with obatoclax. In zebrafish xenograft models, bortezomib combined with obatoclax significantly decreased tumor foci formation.@*CONCLUSIONS@#Bortezomib and obatoclax for dual blockade of protein degradation pathways show synergistic anti-tumor effect in human acute T lymphoblastic leukemia cells.