Figure 6. FP/obatoclax suppresses MM tumor growth in subcutaneous flank murine models, an event diminished by Bim shRNA.

(A–C) Mouse model #1 - subcutaneous (s.c.) flank RPMI8226 model: athymic NCr-nu/nu mice were subcutaneously inoculated in the right rear flank with 5×10⁶ RPMI8226 cells carrying luciferase. Treatment was initiated after luciferase activity was detected (7 days after injection of tumor cells). Mice were treated (indicated by arrow heads) with FP (5mg/kg, i.p.) ± obatoclax (3mg/kg, i.m.), daily for the first three days. After a two-day interval (due to poor absorption of obatoclax after i.m. injection), the schedule was adjusted to twice every three days for an additional three cycles. n = 4 per group. Tumor growth was monitored every other day using the IVIS 200 imaging system (A, left, images shown were captured at day 28), and tumor size measured by calipers (B). When tumor size reached 2,000 mm³, mice were euthanized, and tumors removed from mice (A, right), after which tumor tissues were homogenized and subjected to immunoblot analysis (C). A discernible loss of body weight (< 10% of initial weight) occurred in both obatoclax and FP/obatoclax groups during the first week of treatment, which recovered soon after the treatment schedule was adjusted. There was no discernible loss of body weight in another two groups throughout the experiment. (D) Mouse model #2 – s.c. dual-side flank U266 model: NOD scid gamma mice were subcutaneously inoculated in each flank with 1×10⁷ U266 cells carrying shRNA targeting Bim (shBim, left flank) or negative control (shNC, right flank). Treatment was initiated after tumors were visible (8 days after injection of tumor cells). FP (3mg/kg, i.p.) ± obatoclax (3mg/kg, i.p.) were administered daily for the first four days, followed by once every two days for an additional seven cycles. n = 4 per group. Tumor size was measured every other day (left); when tumor size reached 2,000 mm³, mice were euthanized, and tumors removed from mice (right). There was no significant loss of body weight in any groups throughout the experiment. Tumor volumes were calculated using the formula (L × W²)/2, with L and W representing length and width respectively.