Target-specific agents used in
melanoma are not curative, and
chemokines are being implicated in drug-resistance to target-specific agents. Thus, the use of conventional agents in rationale combinations may result in optimization of
therapy. Because
histone deacetylases participate in
tumor development and progression, the combination of the pan-inhibitor SAHA and
temozolomide might provide a therapeutic advantage. Here, we show synergism between the two drugs in mutant BRAF cell lines, in association with decreased phosphorylation of cell survival
proteins (e.g.,
C-Jun-N-terminal-kinase, JNK). In the spontaneous ret transgenic mouse
melanoma model, combination
therapy produced a significant disease onset delay and down-regulation of
Chemokine (C-C motif) ligand 2 (CCL2), JNK, and of Myeloid-derived suppressor cell recruitment. Co-incubation with a CCL2-blocking-antibody enhanced in vitro cell sensitivity to
temozolomide. Conversely, recombinant CCL2 activated JNK in human
tumor melanoma cells. In keeping with these results, the combination of a JNK-inhibitor with
temozolomide was synergistic. By showing that down-regulation of CCL2-driven signals by SAHA and
temozolomide via JNK contributes to reduce
melanoma growth, we provide a rationale for the therapeutic advantage of the
drug combination. This combination strategy may be effective because of interference both with
tumor cell and tumor microenvironment.