Fighting breast cancer stem cells through the immune-targeting of the xCT cystine–glutamate antiporter
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Tumor relapse and metastatic spreading act as major hindrances to achieve complete cure of breast cancer. Evidence suggests that cancer stem cells (CSC) would function as a reservoir for the local and distant recurrence of the disease, due to their resistance to radio- and chemotherapy and their ability to regenerate the tumor. Therefore, the identification of appropriate molecular targets expressed by CSC may be critical in the development of more effective therapies. Our studies focused on the identification of mammary CSC antigens and on the development of CSC-targeting vaccines. We compared the transcriptional profile of CSC-enriched tumorspheres from an Her2+ breast cancer cell line with that of the more differentiated parental cells. Among the molecules strongly upregulated in tumorspheres we selected the transmembrane amino-acid antiporter xCT. In this review, we summarize the results we obtained with different xCT-targeting vaccines. We show that, despite xCT being a self-antigen, vaccination was able to induce a humoral immune response that delayed primary tumor growth and strongly impaired pulmonary metastasis formation in mice challenged with tumorsphere-derived cells. Moreover, immunotargeting of xCT was able to increase CSC chemosensitivity to doxorubicin, suggesting that it may act as an adjuvant to chemotherapy. In conclusion, our approach based on the comparison of the transcriptome of tumorspheres and parental cells allowed us to identify a novel CSC-related target and to develop preclinical therapeutic approaches able to impact on CSC biology, and therefore, hampering tumor growth and dissemination.
KeywordsCancer stem cell Vaccine Tumorsphere xCT Breast cancer NIBIT 2017
Antibody-dependent cell cytotoxicity
Cancer stem cell
Reactive oxygen species
Roberto Ruiu, Valeria Rolih, Elisabetta Bolli, and Laura Conti produced the results discussed in this review. Roberto Ruiu, Federica Cavallo and Laura Conti provided major contribution in writing and discussing the manuscript. Federica Pericle provided the VLP technology, Gaetano Donofrio the BoHV-4 technology. Elisabetta Bolli and Valeria Rolih wrote and discussed the sections involving VLP and performed the original ELISA assay reported in this review. Giuseppina Barutello and Federica Riccardo wrote and discussed the sections involving the BALB-neuT model and the translatability of the vaccine. Roberto Ruiu produced the figures. Elena Quaglino, Federica Cavallo, Federica Pericle, Irene Fiore Merighi and Laura Conti critically revised the manuscript. All authors read and approved the final version of the manuscript.
This paper was supported by a grant from the Italian Association for Cancer Research (IG 11675) to Federica Cavallo.
Compliance with ethical standards
Conflict of interest
The authors declare that no potential conflicts of interest exist.
All the in vivo experiments were approved by the Italian Ministry of Health, authorization numbers 174/2015-PR, 1042/2016-PR and 500/2017-PR.
Human and animal rights
Mice used for the vaccination experiments reported in this paper were purchased from Charles River Laboratories or bred at the Molecular Biotechnology Center, University of Turin, where all mice were maintained and treated in accordance with the University Ethical Committee and European Union guidelines under Directive 2010/63.
- 2.Clarke MF, Dick JE, Dirks PB, Eaves CJ, Jamieson CH, Jones DL, Visvader J, Weissman IL, Wahl GM (2006) Cancer stem cells–perspectives on current status and future directions: AACR Workshop on cancer stem cells. Cancer Res 66:9339–9344. https://doi.org/10.1158/0008-5472.CAN-06-3126 CrossRefGoogle Scholar
- 3.Gammaitoni L, Leuci V, Mesiano G, Giraudo L, Todorovic M, Carnevale-Schianca F, Aglietta M, Sangiolo D (2014) Immunotherapy of cancer stem cells in solid tumors: initial findings and future prospective. Expert Opin Biol Ther 14:1259–1270. https://doi.org/10.1517/14712598.2014.918099 CrossRefGoogle Scholar
- 9.Conti L, Lanzardo S, Arigoni M, Antonazzo R, Radaelli E, Cantarella D, Calogero RA, Cavallo F (2013) The noninflammatory role of high mobility group box 1/Toll-like receptor 2 axis in the self-renewal of mammary cancer stem cells. FASEB J 27:4731–4744. https://doi.org/10.1096/fj.13-230201 CrossRefGoogle Scholar
- 14.Ponti D, Costa A, Zaffaroni N, Pratesi G, Petrangolini G, Coradini D, Pilotti S, Pierotti MA, Daidone MG (2005) Isolation and in vitro propagation of tumorigenic breast cancer cells with stem/progenitor cell properties. Cancer Res 65:5506–5511. https://doi.org/10.1158/0008-5472.CAN-05-0626 CrossRefGoogle Scholar
- 15.Rovero S, Boggio K, Di Carlo E, Amici A, Quaglino E, Porcedda P, Musiani P, Forni G (2001) Insertion of the DNA for the 163–171 peptide of IL1beta enables a DNA vaccine encoding p185(neu) to inhibit mammary carcinogenesis in Her-2/neu transgenic BALB/c mice. Gene Ther 8:447–452. https://doi.org/10.1038/sj.gt.3301416 CrossRefGoogle Scholar
- 18.Galadari S, Rahman A, Pallichankandy S, Thayyullathil F (2017) Reactive oxygen species and cancer paradox: To promote or to suppress? Free Radic Biol Med 104:144–164. https://doi.org/10.1016/j.freeradbiomed.2017.01.004 CrossRefGoogle Scholar
- 49.Ottestad-Hansen S, Hu QX, Follin-Arbelet VV, Bentea E, Sato H, Massie A, Zhou Y, Danbolt NC (2018) The cystine-glutamate exchanger (xCT, Slc7a11) is expressed in significant concentrations in a subpopulation of astrocytes in the mouse brain. Glia 66: 951–970. https://doi.org/10.1002/glia.23294 CrossRefGoogle Scholar
- 52.De Bundel D, Schallier A, Loyens E et al (2011) Loss of system x(c)- does not induce oxidative stress but decreases extracellular glutamate in hippocampus and influences spatial working memory and limbic seizure susceptibility. J Neurosci 31:5792–5803. https://doi.org/10.1523/JNEUROSCI.5465-10.2011 CrossRefGoogle Scholar
- 56.Kobayashi S, Kuwata K, Sugimoto T, Igarashi K, Osaki M, Okada F, Fujii J, Bannai S, Sato H (2012) Enhanced expression of cystine/glutamate transporter in the lung caused by the oxidative-stress-inducing agent paraquat. Free Radic Biol Med 53:2197–2203. https://doi.org/10.1016/j.freeradbiomed.2012.09.040 CrossRefGoogle Scholar