The Role of reactive oxygen species in cytotoxic immunity against cancer.

What are the roles of reactive oxygen species (ROS) in the cytotoxic immunity against cancer and how can they be targeted to eradicate cancer?

Reactive Oxygen Species (ROS), Cytotoxic Immunity and Cancer.

The role of the immune system in the fight against cancer is undeniable. In this regard, Natural killer (NK) cells and cytotoxic T lymphocytes (CTL) are respectively innate and adaptive cytotoxic lymphocytes dedicated to kill cancer cells. In the lab, we are using a model of glioblastoma multiforme (GBM), a very lethal primary brain tumor, to investigate the cell death mechanism triggered by these cytotoxic lymphocytes and how they are regulated by microenvironmental metabolites such as reactive oxygen species (ROS) in order to design new therapeutics. To meet this goal, we use combined approaches at the intersection of biochemistry, chemistry, cell biology, proteomics, genomics and bioinformatics.

  • I committed all my effort to beat cancer.

Group Members
Key Publications

The role of the immune system against cancer was demonstrated as primary and acquired immunodeficiency is associated with increased susceptibility to cancer. Furthermore, the size of the immune infiltrate in primary tumor is a good prognosis for patient survival, explaining why blockage of immune checkpoint receptors is a very promising immunotherapy strategy. However, the occurrence of cancers and the resistance to blockage of these immune checkpoint receptors are the direct demonstration that tumor cells are capable of evading the host immune surveillance, and this ability to escape immune recognition and elimination, essential for cancer development, is now considered as a new feature in the hallmark of cancer. This is also true for glioblastoma multiforme, a very aggressive primary brain tumor, the cancer model under investigation in the lab. The natural killer (NK) cells and cytotoxic T lymphocytes (CTL) are the cytotoxic lymphocytes dedicated to engage and kill the cancer cells. A better understanding of factors regulating the dynamics of interaction between cancer cells and these cytotoxic lymphocytes is necessary to develop new therapeutics harnessing the patient own immune system to beat the disease.

 In the lab, we focus on the role of immune inhibitory metabolites such as reactive oxygen species (ROS). ROS are pleotropic factors resulting from the cancer cell metabolic shift and the hypoxic microenvironment and they are strong candidates capable of orchestrating the reprogramming of the tumor microenvironment for tumor progression. Supporting this hypothesis, H2O2 modulates genes expression following the activation of redox responsive transcription factors. In addition, some of our preliminary data suggest that the cancer cell redox state could regulate lymphocyte function. Interestingly, we have also found that cancer cells, under the attack of the cytotoxic lymphocytes, experienced a massive ROS production that is necessary for their demise. Taken together ROS play a complex role in the dynamics of cancer-immune cell interaction. The Martinvalet’ lab investigates the role of the ROS in the cytotoxic immunity against glioblastoma multiforme both from the standpoint of the target cancer cells and the cytotoxic lymphocytes.


Reactive Oxygen Species (ROS), Cytotoxic Immunity and Cancer.

Reactive Oxygen Species:

Reactive oxygen species (ROS) result from the partial reduction of oxygen. This large family of reactive compounds includes both radical species; superoxide anion (O2•-), hydroxyl radical (OH), nitric oxide (NO) and non-radical species; hydrogen peroxide (H2O2), hypochlorous acid (HOCl), peroxynitrite (ONOO-). Interestingly, ROS are very pleotropic compounds. They are involved in both physiological processes such as inflammation, vasoconstriction, signal transduction, cell migration, differentiation, proliferation, and pathological conditions as they are common determinants of various forms of cell death, e.g. apoptosis, necrosis/necroptosis, ferroptosis, pyroptosis, and autophagic cell death. The molecular understanding of their biogenesis and mode of action during cell death is still not well understood. In the case of cytotoxic lymphocyte-mediated cell death, we have found that ROS originated from the disruption of the respiratory chain complex I.

Cytotoxic immunity:

Natural killer (NK) cells and cytotoxic T lymphocytes (CTL) are effectors respectively of the innate and the adaptive cytotoxic immune response against stressed target cells such as cancer cells or pathogen-infected cells. Cytotoxic lymphocyte-mediated cell death requires target cell cytosolic delivery of the effector proteases granzymes. Interestingly, we have found that cytotoxic lymphocytes also eradicate their target cells in a ROS-dependent manner. Granzyme A and B (GA and GB) induce ROS-dependent death by entering the target cells mitochondria to cleave NDUFS3, NDUFV1, NDUFS2 and NDUFS1 subunits of the NADH:ubiquinone oxidoreductase complex I of the electron transport chain (ETC) (Martinvalet et al. 2005, Martinvalet et al. 2008 and Jacquemin et al. 2015). Cleavage of the complex I subunits triggers the leaking of electrons, leading to a rapid and robust mitocentric ROS production, loss in complex I, II, and III activity, disorganization of the respiratory chain, impaired mitochondrial respiration, and loss of the mitochondrial cristae junction (Jacquemin et al. 2015). Unexpectedly, granzymes and caspase 3 enter the mitochondria independently from TOM40 complex, the organelle known entry gate, and instead use SAM50 channel as a translocase (Chiusolo et al. 2017). SAM50 is the core channel of the mitochondrial sorting and assembly machinery dedicated to insert de novo β-barrel proteins into the mitochondrial outer membrane. When preventing granzymes and caspase 3 from accessing the mitochondria matrix, there is a significant reduction of their cytotoxicity, suggesting that their mitochondrial entry is an unanticipated critical step for ROS-dependent cell death. One particular goal in the lab is to further investigate the role of the ROS for the outcome of the anti-tumoral immune response, both from the standpoint of the target cells and the effector cells.




Using a model of glioblastoma multiforme, a highly heterogeneous and aggressive primary brain tumor, we found that the mitochondrial morphology and ER-mitochondria contacts control glioma cell stemness and surface expression of glycans in order to regulate their susceptibility to cytotoxic lymphocytes (Bassoy et al. 2017). Our results have indicated that due to the defects in the ER-mitochondria contacts, glioma stemlike cells are not able to bring glycans at their surface. We believe this is due to a defect in lipid biosynthesis or in its bioavailability (Bassoy et al. 2016; Bassoy et al. 2017). In fact, stable contacts between ER and mitochondria harmonize the function of these two organelles and are necessary for lipid biosynthesis and transfer. Moreover, the tentacular ER, the cell largest network, makes contacts not only with the mitochondria, but also with the early and the late endosomes and the peroxisomes, in order to control, lipids biosynthesis and distribution among other things. It is therefore possible that these other interorganellar contacts also play a role in glioma stemlike cell biology. Another aspect of our work is to investigate the role of interorganellar contact sites in the biology of cancer stem cells and their susceptibility to cytotoxic lymphocytes and chemotherapies. We are also investigating the role of the ROS in the remodeling and reprogramming of the tumor ecosystem since cancer cells have an hypoxic and oxidized microenvironment.

Enrico Dotta

MD Student

Stefania Lionello

PhD Student

  1. Esen Yonca Bassoy, Atsuko Kasahara, Valentina Chiusolo, Guillaume Jacquemin, Emma Boydell, Sebastian Zamorano, Cristina Riccadonna, Serena Pellegatta, Nicolas Hulo, Valérie Dutoit, Madiha Derouazi, Pierre Yves Dietrich, Paul R. Walker and Denis Martinvalet. ER-mitochondria contacts control surface glycan expression and sensitivity to killer lymphocytes in glioma stem-like cells. EMBO J. o This article was offered the Cover page of the journal and was highlighted by a News & Views.
  2. Valentina Chiusolo#, Guillaume Jacquemin#, Esen Yonca Bassoy, Lavinia Liguori, Michael Walch, Vera Kozjak-Pavlovic and Denis Martinvalet. Granzyme B enters mitochondria in a Sam50, Tim22 and mtHsp70-dependent manner to induce apoptosis. Cell Death Differ. 2017 Apr;24(4):747-758.
  3. Bassoy EY, Chiusolo V, Jacquemin G, Riccadonna C, Walker PR, Martinvalet D. Glioma Stemlike Cells Enhance the Killing of Glioma Differentiated Cells by Cytotoxic Lymphocytes. PLOSOne 2016 11(4):e0153433. doi: 10.1371/journal.pone.0153433. eCollection
  4. Jacquemin G, Margiotta D, Kasahara A, Bassoy EY, Walch M, Thiery J, Lieberman J, Martinvalet D. Granzyme B-induced mitochondrial ROS are required for apoptosis. Cell Death Differ. 2015.
  5. Walch M, Dotiwala F, Mulik S, Thiery J, Kirchhausen T, Clayberger C, Krensky AM, Martinvalet D, Lieberman J. Cytotoxic cells kill intracellular bacteria through granulysin-mediated delivery of granzymes. 2014.
  6. Zhu P*, Martinvalet D*, Chowdhury D, Zhang D, Schlesinger A, Lieberman J. The cytotoxic T lymphocyte protease granzyme A cleaves and inactivates poly(adenosine 5'-diphosphate-ribose) polymerase-1. 2009.
  7. Martinvalet D, Dykxhoorn DM, Ferrini R, Lieberman J. Granzyme A cleaves a mitochondrial complex I protein to initiate caspase-independent cell death. Cell
  8. Martinvalet D, Zhu P, Lieberman J. Granzyme A induces caspase-independent mitochondrial damage, a required first step for apoptosis. Immunity


Denis Martinvalet

  • 2000-2001: Research Fellow, Manitoba Institute of Cell Biology, Winnipeg, CA.
  • 2001-2006: Research Fellow, Immune Disease Institute, Harvard Medical School, Boston, USA.
  • 2006-2009: Instructor, Immune Disease Institute, Harvard Medical School, Boston, USA.
  • 2009-2016: Group Leader, Dept. Cell Physiology and Metabolism, University of Geneva, CH.
  • 2018-   Assistant Professor, Dept. of Biomedical Sciences, University of Padua, IT.

Selected Awards

  • 2016 – Member of the European Academy of Tumor Immunology
  • 2015 – Member of the American Association for the advancement of science.
  • 2007-2009 – Board of Directors, Sickle Cell Disease Association of America, Boston Chapter.