Chemoprevention of familial adenomatous polyposis by bromo‐noscapine (EM011) in the Apc^Min/+ mouse model

Abstract

Germline mutation of the tumor suppressor gene, adenomatous polyposis coli (APC), is responsible for familial adenomatous polyposis (FAP) with nearly 100% risk for colon cancer at an early age. Although FAP is involved in only 1% of all colon cancer cases, over 80% of sporadic cancers harbor somatic mutations of APC. We show here that bromo-onoscapine (EM011), a rationally-designed synthetic derivative of a natural non-toxic tubulin-binding alkaloid-noscapine, that reduces the dynamics of microtubules, causes a reversible G2/M arrest in wild type mouse embryonic fibroblasts (MEFs), but an aberrant exit from a brief mitotic block, followed by apoptosis in MEFs after APC deletion with siRNA. Furthermore, both β-catenin levels and activity fell to half the original levels with a concomitant reduction of cell proliferation-inducing cyclin D1, c-Myc, and induction of cytostatic protein p21 prior to caspase-3 activation. Additionally, we show a statistically significant reduction in the number of newly emerging intestinal polyps (to 35% compared with untreated mice) as well as the mean size of polyps (to 42% compared with untreated mice) in EM011-treated ApcMin/+ mice as compared to their sham-treated control littermates. The remaining polyps in the EM011 treated group of ApcMin/+ mice showed evidence of elevated apoptosis as revealed by immunohistochemistry. We failed to detect any evidence of histopathological and hematological toxicities following EM011 treatment. Taken together, our data are persuasive that a clinical trial of EM011 is possible for the prevention/amelioration of polyposis in FAP patients.

Efficient Activation of Apoptotic Signaling during Mitotic Arrest with AK301

“…Although microtubule and mitosis targeting chemotherapies are not typically used to treat colon cancer, our findings here, and reports by other groups, suggest that these therapies may in some cases be advantageous [ 43 – 45 ]. Colon cancers with microsatellite instability are usually p53-normal and have a defective CHFR mitotic checkpoint, and are therefore an interesting target for AK301 (and similarly acting agents), particularly if they also have an APC mutation.…”

Molecular hydrogen suppresses activated Wnt/β-catenin signaling

“…L cells were transfected with plasmids using Lipofectamine 2000 (Invitrogen). Sequences of siRNAs against APC and Axin1 were adopted from previous studies 42 43 and were synthesized by Sigma-Aldrich. To knock-down APC, L cells were transfected with 280 pmol APC-targeting siRNA (APC-siRNA#1 or APC-siRNA#2) or control siRNA (Cont-siRNA) by Lipofectamine RNAiMax (Invitrogen).…”

Progress Toward the Development of Noscapine and Derivatives as Anticancer Agents

“…Bar = 20 µM. Reproduced from Li et al94 The antitumor activity of 6 and 10 on human non-small cell lung cancer cells has been thoroughly investigated. In vitro cytotoxicity of 6 in H460 cells treated with increasing doses of 6…”