A novel gamma-lactam-based histone deacetylase inhibitor potently inhibits the growth of human breast and renal cancer cells.

We evaluated the novel gamma-lactam-based analogue, KBH-A145, for its anticancer activities. KBH-A145 markedly inhibited histone deacetylase (HDAC) activity in vitro and in vivo to an extent comparable to suberoyl-anilide hydroxamic acid (SAHA). The proliferation of various types of cancers was significantly suppressed by KBH-A145, among which MDA-MB-231 and MCF, human breast cancer cells and ACHN human renal cancer cells, were most sensitive. This was accompanied by induction of p21(WAF1/Cip1) through compromised recruitment of HDAC1, which leads to hyperacetylation of its promoter region and thus arrested both cells in the G(2)/M phase. Interestingly, this compound induced apoptosis of MDA-MB-231 cells, but not ACHN cells, through cleavage of poly(ADP-ribose) polymerase (PARP). Taken together, these results show that this novel gamma-lactam-based HDAC inhibitor potently inhibits the growth of human breast and renal cancer cells. Thus KBH-A145 is a potential therapeutic agent for the treatment of these types of cancer.