An emerging new class of targeted therapeutic molecules against the
enzyme fatty acid amide hydrolase (FAAH) is a novel series of pyrrolo-1,5-benzoxa(thia)zepine compounds. A member of this family, pyrrolo-1,5-benzoxazepine-15 (PBOX-15), is a
tubulin depolymerizing agent displaying a proapoptotic activity in a variety of human
tumor cell types, including those derived from both solid and
hematological malignancies, with minimal toxicity towards normal blood and bone marrow cells. In this study, we evaluated the PBOX-15-mediated effects in human
colorectal cancer cell (CRC) lines. The compound, used at doses equal to or greater than 1 μM inhibits the proliferation of human CRC cell lines in a dose- and time-dependent manner, inducing a significant cell cycle arrest in the G2/M phase. DNA fragmentation assays and western blot analysis demonstrated that treatments prolonged over 48 h triggered a strong activation of the intrinsic apoptotic pathway as indicated by activation of
caspase-3,
caspase-9 and PARP. Moreover, nanomolar doses of
PBOX-15, unable to cause microtubule depolymerization, significantly improved the
oxaliplatin and 5-fluouracil-induced anti-proliferative effects in CRC cell lines. These results showed, for the first time, that
PBOX-15 represents a promising compound for the treatment of human CRC and a strong candidate for novel therapeutic options.