nrf2 inhibitor In addition ABC transporters are important ma

In addition, ABC-transporters are important markers for the isolation and analysis of stem nrf2 inhibitor and cancer propagating (stem) cells (Goodell et al., 1996; Zhou et al., 2001; Chiba et al., 2006; Haraguchi et al., 2006; Hirschmann-Jax et al., 2004; Kondo et al., 2004). We previously reported that ABCG2 was highly expressed on the surface of cancer stem-like side population (SP) cells from various cancer cell lines. Treatment with MS209 (dofequidar), an inhibitor of both P-gp and ABCG2, effectively sensitize the cancer stem-like SP cells to chemotherapeutic agent such as mitoxantrone or CPT-11 (Katayama et al., 2009). In this study, we showed that P-gp overexpression plays an important role in acquired crizotinib and ceritinib resistance. In addition, our results imply that the existence of ABC transporters-overexpressing cells as a minor population in the TKI treatment-naïve cancer may be a seed of resistant tumor development, resulting in the prevention of complete cure of cancer by TKIs, such as ceritinib or crizotinib. Further studies are needed to clarify the importance of ABC transporters (P-gp) in acquired TKI resistance and innate TKI resistance.
Author Contributions
Acknowledgments We thank Y. Togashi, S. Baba, T. Uenami, K. Komatsu, and Y. Sugiyama at the Japanese Foundation for Cancer Research (JFCR) for help with the deep sequencing (Y.T.), patient care (T.U.) and cytological examination (S.B., K.K. and Y.S.). Several patients participated in a clinical trial funded by Novartis. We also thank Novartis for kindly providing 14C-ceritinib. Experiments, data collection, data analysis, and manuscript drafting was supported in part by MEXT/JSPS KAKENHI grant number 15H02368 (to N. Fujita), 25710015 and 15K14412 (to R. Katayama), and 25250020 (to K. Takeuchi), grant number 15ck0106116h0002 from the MHLW/AMED (to R. Katayama and S. Kitazono), and by a research grant of the Princess Takamatsu Cancer Research Fund (to N. Fujita). We have not been paid to write this article by any pharmaceutical company or other agency.
Introduction Traditional vaccine development has focused on highly immunogenic live-attenuated or inactivated pathogen platforms. However, safety concerns associated with these platforms, as well as advances in vaccine manufacturing and antigen characterization, have turned interest toward protein-based vaccines. Protein-based vaccines are designed to elicit an immune response against a specific antigen with known protective capabilities. While they are a safer alternative to traditional vaccines, they are also less immunogenic and confer less durable immune responses. Among protein-based vaccine platforms are virus-like particles (VLPs), which are essentially empty viral particles incapable of replicating in the host. VLPs have been heralded as one of the most promising future vaccine platforms, and some examples of VLPs are already in the clinic, including Cervarix, a Human Papilloma Virus (HPV) vaccine (Pitoiset et al., 2015; Einstein et al., 2014a, 2014b). Adjuvants are often included in protein-based vaccines in order to regulate antigen dispersal and to enhance immunogenicity. Recent advances in adjuvant discovery have highlighted the potential importance of pattern recognition receptor (PRR) ligands as vaccine adjuvants (Coffman et al., 2010; Steinhagen et al., 2011; Brunner et al., 2010; O\'Hagan and Fox, 2015). Traditional alum-based vaccine adjuvants may not work for vaccines requiring a cytotoxic, Th1-skewed immune response, whereas PRR agonists can be used to direct the type of immune response elicited against the vaccine antigen. AS04, an aluminum salt adjuvant that includes the Toll-like receptor (TLR) 4 ligand monophosphoryl lipid A, has been approved in Fendrix and Cervarix, Hepatitis B and HPV vaccines, respectively, and several other PRR agonist-based adjuvants are currently in clinical trials (Surquin et al., 2011; Beran, 2008; Einstein et al., 2014a, 2014b). In this study, four adjuvants were tested in combination with the Ebola virus VLP vaccine to determine their impact on durable protection. Alhydrogel is a well-characterized aluminum hydroxide adjuvant, which is currently in several FDA-approved vaccines. Alhydrogel provides a depot effect whereby antigen is released more slowly in vivo, resulting in prolonged antigen exposure, which may or may not contribute to adjuvantcy (Hutchison et al., 2012). Additionally, alhydrogel has been shown to activate the inflammasome, which may contribute to the immunogenicity of alhydrogel-based vaccines (Guven et al., 2013; Gupta, 1998; Hogenesch, 2002; Marrack et al., 2009). PolyICLC is a double-strand RNA stabilized by poly-L-lysine in carboxymethylcellulose (Levy et al., 1975). It signals through TLR3 and potentially MDA5 receptors, eliciting a strong type I IFN response, and it skews the immune response toward a Th1 profile response (Wang et al., 2010; Alexopoulou et al., 2001; Nemes et al., 1969). PolyICLC has been in multiple clinical trials for both therapeutic and vaccine purposes (Martins et al., 2015b). There are three different classes of CpG molecules, which target different cell subsets and receptors and have different recognition in mouse and human cells (Verthelyi et al., 2001; Hartmann et al., 2003; Marshall et al., 2003). The CpG examined here is a class C CpG (2395), meaning that it signals through both pDC and B cells, impacting type I IFN production, antigen-presenting cell (APC) maturation, and NK cell activation (Marshall et al., 2003). CpG molecules (specifically 7909) have been in multiple clinical trials as vaccine adjuvants; the specific CpG tested in this work has not been in clinical trials but was selected as it targets both human and murine TLR9 and it has both Class A and B activation characteristics. Finally, MPLA is a TLR4 agonist, which is comparable to MPL, the active component of the GSK adjuvant AS04 (Einstein et al., 2014a, 2014b). MPLA has been shown to be highly effective as an adjuvant, particularly in combination with an aluminum-based adjuvant like alhydrogel or a nanoparticle formulation (Bohannon et al., 2013).