Figure 3.

Combining Obatoclax with cisplatin further reduces clonogenic potential and further increases apoptosis. The inclusion of pre-miR-34a in combination treatments can abrogate pro-apoptotic effects. Treatment with Obatoclax as a single agent caused a reduction of clonogenicity in all 3 MI-BC cell lines (p < 0.001 for all 3 cell lines) (T24, TCCSuP, and 5637 were treated with IC₃₀ value concentations of Obatoclax; 25, 60, and 40 nM, respectively) (A); Further reductions were observed when Obatoclax was combined with cisplatin (5 μM), the standard of care treatment for MI-BC (~2.5-fold (p < 0.001), ~2.0-fold (p < 0.001), and ~1.5-fold (p < 0.05) reductions were observed in T24, TCCSuP, and 5637, respectively). Combining Obatoclax with pre-miR-34 treatment also caused further reductions in clonogenicity compared to treatment with Obatoclax or pre-miR-34a as single agents (~1.7-fold (p < 0.001), ~1.2-fold (p < 0.01), and ~2.0-fold (p < 0.001) reduction, respectively). In T24 and TCCSuP, the Obatoclax + cisplatin outperformed the Obatoclax + pre-miR-34a treatment (~2.0-fold (p < 0.05), ~1.2-fold (p < 0.05) reduction, respectively), but the reverse was true in 5637 cells (~2-fold (p < 0.001) reduction). Combining cisplatin with pre-miR-34a, or combining all 3 treatments (Obatoclax + cisplatin + pre-miR-34a) did not result in any further reduction in clonogenicity compared to Obatoclax + cisplatin. Apoptosis assays conducted using 5637 cells demonstrated that the Obatoclax + cisplatin outperformed any of the other treatments (B). It is noteworthy that combining pre-miR-34a with Obatoclax + cisplatin caused a dramatic decrease in apoptosis compared to treatment with Obatoclax + cisplatin (32.9% compared to 42.1%, respectively). (Veh = vehicle control, Cis = cisplatin, 34a = pre-miR-34a, Obato = Obatoclax). (* = p < 0.05, ** = p < 0.01, *** = p < 0.001)