Fig. 5.

Metformin (MET) can replace DPI in the synthetically lethal combination in HK1⁻HK2⁺ MM cells. (A) The combination of HK2-ASO1 and MET causes selective synthetic lethality in HK1⁻HK2⁺ MM cells. Cells were pre-treated with HK2-ASO1 (10 μM) for 3 days, followed by the addition of MET (5 mM) for another 3 days. Cell viability was determined trypan blue staining. (B) The combination of HK2-ASO1 and MET causes selective apoptosis in OPM2 MM cells. Cells were pre-treated with HK2-ASO1 (10 μM) for 3 days, followed by the addition of MET (5 mM) for another 3 days. Apoptosis (APO) was determined by quantification of all Annexin V-positive events. (C) PER sensitized OPM2 cells to apoptosis induced by the HK2-ASO1/MET combination. Cells were pre-treated with HK2-ASO1 (5 μM) for 3 days, followed by the addition of MET (2.5 mM) and PER (5 μM) for another 3 days. Apoptosis (APO) was determined by quantification of all Annexin V-positive events. (D) Effects of single agents and combination treatments on RPMI8226/LUC cells with and without BMSC coculture. In cocultures, RPMI8226/LUC cells and BMSCs were in 1:2 ratio. Cells were exposed to 10 μM ASOs for an additional period of 3 days, prior to the exposure of 15 nM DPI, 2.5 mM MET, and/or 5 μM PER for another 3 days. RPMI8662/LUC cell proliferation was determined by measuring luminescence intensity. (E) Representative images of co-cultures of RPMI8226/LUC and BMSCs with indicated treatments showed in panel D. (F) The combinations of HK2-ASO1/MET/PER and HK2-ASO1/DPI/PER show no demonstrably significant differences in suppressing xenograft OPM2 tumor progression. When tumors reached 200 mm³ (day 1), xenografts were randomized into indicated groups (n = 10/group). HK2-ASO1 treatment was started on day 1 at 50 mg/kg s.c. daily. DPI (2 mg/kg, daily i.p.), MET (250 mg/kg, daily i.p.), and PER (30 mg/kg, daily i.p.) were started on day 3. Treatments were given for 5 days per week, with a 2-day break between weeks. NS, not significant. (G) Disease progression in the HK1⁻HK2⁺ RPMI8226/LUC disseminated xenograft model was monitored by BLI. BLI measurement in photons per second per cm² per steradian (p/s/cm²/sr) was translated to color to indicate disease activity in the mice by the scales shown at far right. (H) Quantification of whole mouse BLI photons in panel G. ***, P < 0.001. ****, P < 0.0001.