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Background: Nuclear factor-κB (NF-κB) has been implicated in tumor cell proliferation and survival and in tumor angiogenesis. We sought to evaluate the effects of curcumin, an inhibitor of NF-κB, on a xenograft model of disseminated neuroblastoma., Methods: For in vitro studies, neuroblastoma cell lines NB1691, CHLA-20, and SK-N-AS were treated with various doses of liposomal curcumin. Disseminated neuroblastoma was established in vivo by tail vein injection of NB1691-luc cells into SCID mice, which were then treated with 50 mg/kg/day of liposomal curcumin 5 days/week intraperitoneally., Results: Curcumin suppressed NF-κB activation and proliferation of all neuroblastoma cell lines in vitro. In vivo, curcumin treatment resulted in a significant decrease in disseminated tumor burden. Curcumin-treated tumors had decreased NF-κB activity and an associated significant decrease in tumor cell proliferation and an increase in tumor cell apoptosis, as well as a decrease in tumor vascular endothelial growth factor levels and microvessel density., Conclusion: Liposomal curcumin suppressed neuroblastoma growth, with treated tumors showing a decrease in NF-κB activity. Our results suggest that liposomal curcumin may be a viable option for the treatment of neuroblastoma that works via inhibiting the NF-κB pathway., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Identification and reversal of treatment resistance mechanisms of clinically refractory tumor cells is critical for successful cancer therapy. Here we show that ATP-binding cassette member B5 (ABCB5) identifies therapy-refractory tumor cells in colorectal cancer patients following fluorouracil (5-FU)-based chemoradiation therapy and provide evidence for a functional role of ABCB5 in colorectal cancer 5-FU resistance. Examination of human colon and colorectal cancer specimens revealed ABCB5 to be expressed only on rare cells within healthy intestinal tissue, whereas clinical colorectal cancers exhibited substantially increased levels of ABCB5 expression. Analysis of successive, patient-matched biopsy specimens obtained prior to and following neoadjuvant 5-FU-based chemoradiation therapy in a series of colorectal cancer patients revealed markedly enhanced abundance of ABCB5-positive tumor cells when residual disease was detected. Consistent with this finding, the ABCB5-expressing tumor cell population was also treatment refractory and exhibited resistance to 5-FU-induced apoptosis in a colorectal cancer xenograft model of 5-FU monotherapy. Mechanistically, short hairpin RNA-mediated ABCB5 knockdown significantly inhibited tumorigenic xenograft growth and sensitized colorectal cancer cells to 5-FU-induced cell killing. Our results identify ABCB5 as a novel molecular marker of therapy-refractory tumor cells in colorectal cancer patients and point to a need for consistent eradication of ABCB5-positive resistant tumor cell populations for more effective colorectal cancer therapy.