Figure 5. Evaluation of syringolog-1 activity in primary MM cells from patients.

(A–B) Cytotoxicity of syringolog-1 (Sy) or bortezomib (Btz) was tested on 8 primary MM cells. IC₅₀ values of Sy on each primary MM cell were calculated from the triplicate experiments. A. 5 cases clinically sensitive to Btz-based therapy. (B) 3 cases clinically refractory to Btz-based therapy. RR: relapsed and or refractory, ND: newly diagnosed. (C) 20S proteasome activities in 8 primary MM cells were evaluated after incubation with or without 10 nM of Sy or Btz for 6 h. (D) Four peripheral blood mononuclear cells from healthy individuals were analyzed for cytotoxic effect induced by Sy treatment at the indicated dose for 48 h. (E) Accumulation of poly-ubiquitinated proteins and expression of cleaved caspase-3 were evaluated in 3 primary MM cell lines after incubation with 10 nM of syringolog-1 or Btz for 16 h. ^* represents statistically significant (p < 0.05) by Dunnett’s post-test.