Interferon Regulatory Factor was able to restore MHC-1 expression and cellular immune complex formation in neuroblastoma cell lines. However, in intestinal cancer, NF-��B signalling enhances Wnt activation and induces dedifferentiation of non-stem cells that acquire tumor-initiating capacity. These observations suggest that NF-��B signalling may be a therapeutic target depending on the type of cancer. Various lines of evidence suggest that stem-like cells are responsible for failure of long-term remission. Thus, eradicating tumors may be difficult because conventional treatments target the bulk of tumor cells rather than these tumor-initiating stem cells which are chemoresistant. The sidepopulation assay is widely used for the identification and isolation of stem-like cells from cancers based on their capacity to exclude dyes such as Hoechst 33342. To determine whether the RA/MG132 combination alters the population of stem-like cells of neuroblastomas, we analysed the expression of stem cell-related markers such as Oct4, Nanog and Sox2 which are key regulators of embryonic stem cell maintenance and are overexpressed in different cancers, including neuroblastoma. The neural progenitor markers Nestin and CD34 are also expressed in neuroblastoma cells. The exact role of these stem cellrelated genes in tumors is not completely clear, but Nanog, Oct4 and Nestin have been associated with a more immature and aggressive cell phenotype. In our studies, protein levels of Oct4, Sox2, and Nanog were significantly reduced by RA/MG132 combined treatment. Remarkably, this reduction of stem cell markers persisted during the 5 days after treatment cessation. Moreover, the proportion of live cells 1431699-67-0 expressing Nestin and Oct4 was significantly lower in cells receiving RA/MG132 than in control cultures or those treated with only one of the compounds. This effect was accompanied by persistent apoptosis and differentiation of those cells that escaped apoptosis, suggesting that RA/MG132 may be beneficial to prevent neuroblastoma relapse. The standard treatment for high-risk neuroblastoma patients includes RA and immunotherapy with anti-GD2 antibodies. The objective of this approach is eradication of minimal residual disease which is 1629249-40-6 structure present in over half of children who have achi
