Myeloid cell leukemia 1 (Mcl-1) is an anti-apoptotic protein which is overexpressed in various
leukemia and other cancers [1]. Mcl-1 has a very short half-life [2], which has been suggested as a
molecular mechanism for cells to switch into either the survival or apoptotic pathways in response to
different stresses [3]. Recently, it has been demonstrated that downregulation of Mcl-1 by various
pharmacological agents or genetic approaches dramatically increases ABT-737 lethality in various
malignant cell types [4]. Different strategies for targeting Mcl-1 include (i) small interfering RNA [5]
(ii) small-molecule inhibitors [6] and (iii) peptide inhibitors [7]. In recent years, therapeutic
vaccination with synthetic peptides derived from anti-apoptotic proteins such as Mcl-1 has emerged
as a promising strategy against hematological cancers.
In this study, 34 overlapping 20-mer peptides, spanning the entire Mcl-1 protein, were adjuvanted
with cationic liposomes [8] and tested in three different mouse strains with varied Major
Histocompatibility Complex (MHC) haplotypes (FVB [H-2q], CB6F1[H-2b/d], B6CBAF1 [H-2b/k])
to identify immunogenic CD4+ T-cell epitopes.