Research
Tumor microenvironnement and resistance to treatment : A. Turtoi

Axis 1:  Identification of CAF subpopulations involved in tumorigenesis

Intratumoral heterogeneity has been extensively studied in cancer cells. However, the heterogeneity of other cells in the tumor stroma remains a scarcely explored subject.  Using various methodological approaches, our aim is to characterize the different subpopulations of CAFs in the TME and determine their function in tumorigenesis.

Our team has in the past identified defensive CAFs with antitumor properties in breast cancer, notably ASPN+ CAFs (Maris P et al. Turtoi A. Plos Medicine 2015) and hepatocellular carcinoma, PRELP+ CAFs (Chiavarina et al. Turtoi A. Oncogene 2022) (Figure 1). Fostering these cells, rather than targeting them, prevents tumor progression. We have described the different CAF subtypes present in colorectal cancer (CRC) liver metastases using single cell analysis and RNAseq. In particular, this work led to the discovery of LTBP2+ CAF, a subgroup of CAFs involved in collagen matrix remodeling and desmoplastic reaction (Giguelay A et al, Turtoi A*, Colinge J*. Theranostics. 2022). Finally, in collaboration with Gumma University (Japan), we used spatial transcriptomics to determine the spatial heterogeneity of different CAF subpopulations in a cohort of tumors from breast cancer patients (N=75) (Honda CK et al.,Turtoi A. Theranostics. 2024). Our present efforts focus on new cancer cell – CAF interactions that antagonize tumor development. We are specifically interested in metabolite – metabolite receptor communication systems and how these signals participate in liver cancer progression.

Figure 1: The new concept of tumor heterogeneity: the smallest element is the cancer cell / CAF pair, which engages in a molecular dialogue. Two opposite cases are represented: the CAF can display either a defensive or a collaborative phenotype, but the transition between these two states is continuous.

Axis 2: Function and targeting of soluble microenvironment factors in cancer cachexia in colorectal cancer

One third of cancer patients die from weight loss caused by the loss of muscle and fat tissue, linked to a complex metabolic syndrome known as cachexia. As a result of tumor-induced metabolic reprogramming, muscle and fat cells degrade their contents to produce energy. Today, cachexia remains poorly understood, and there is no treatment to halt the process. High levels of inflammatory cytokines in cachexia patients leads to a combination of systemic organ damage, such as muscle atrophy, decreased appetite and metabolic disorders. Our team is interested in TGF-β as a key player, because it’s signaling is a hallmark of aberrant inflammation in both cancer and cachexia. Here, we aim to better understand the function of TGF-β and its targets and to clarify its underlying mechanism of action, such as muscle degradation by autophagy. In addition, we have recently developed a bispecific antibody (BsAb) capable of selectively eliminating soluble protumoral factors, including IL-6 (patent WO2020104496, Neiveyans et al, 2019) and TGF-β, within the TME of solid tumors. These BsAbs combine targeting of the type 1 transferrin receptor (TfR1) overexpressed in the majority of cancers with pH-dependent binding to the soluble factor. Such a BsAb enable the removal of soluble factors from the TME by a sweeping mechanism enabled by the continuous recycling of the antibody in the endosomes of cancer cells. Drawing on our expertise in antibody engineering and collaborations within Labex MabImprove (link: https://mabimprove.univ-tours.fr/fr/), we are using antibody phage and yeast display techniques to select recycling antibodies and antibodies with conditional pH-dependent binding. In this way, the TGF-β targets involved in cachexia can also be specifically targeted with these novel antibodies.

Axis 3: Cancer biomarkers - Detection of soluble biomarkers of pancreatic cancer in endoscopic ultrasound-guided fine-needle aspiration samples.

Pancreatic ductal adenocarcinoma (PDAC) accounts for 90% of pancreatic cancers. Its prognosis is poor, and more than half of patients develop metastases immediately after diagnosis, because the symptoms of pancreatic ductal adenocarcinoma are not very specific. Thus, specific diagnosis is the most promising tool for improving the management of this cancer, there is an urgent need to find diagnostic biomarkers.  Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is today the cornerstone of PDAC diagnosis. Nevertheless, it is an invasive procedure that is generally only used in patients suspected of having PDAC and not in the asymptomatic population. We have recently developed a unique, non-destructive and fully OMICS-compliant methodology for extracting soluble molecules from EUS-FNA biopsies (EXPEL). We conducted a retrospective study of 58 patients with suspected pancreatic lesions who underwent EUS-FNA (collaboration Pr. Eric Assenat, CHU Montpellier). Protein extracts from EUS-FNA fluid were analyzed by mass spectrometry. Proteomic and clinical data were modeled by supervised statistical learning to identify protein markers and clinical variables that distinguish PDAC (collaboration Pr. Jacques Colinge). Statistical modeling revealed a protein signature for PDAC screening that achieved high sensitivity and specificity. We also developed a protein signature score (PSS) to guide the diagnosis of PDAC (Figure 2). Combined with patient age, the PSS allowed us to identify PDAC patients over 54 years of age with 100% certainty (PANEXPEL clinical trial: NCT03791073 and Souche R, Tosato G, et al. Colinge J & Turtoi A. Endoscopy. 2021).

Figure 2: PANEXPEL workflow and PSS (19 proteins and clinical data) for PDAC diagnosis

Our future objectives are: (i) to improve the signature of the primary biomarker by performing additional MS analyses of fluids and (ii) to validate the accuracy of a combination of biomarkers in prospectively collected patient serum samples (patient recruitment underway at Montpellier University Hospital, forthcoming at Toulouse University Hospital) (PanEXPEL2 cohort (NCT04370574)).

Techniques used in the laboratory: Metabolomics, proteomics, phage display, yeast display, xenografts into the chicken chorioallantoic membrane, autophagy measurement, electron microscopy.

PI expertise

Andrei Turtoi, PhD, HDR, Inserm, Team leader

Keywords: Tumoral microenvironment, cancer associated fibroblasts, TGF-b signaling, metabolism, mass spectrometry-based OMICS;

Scientific director of MAMMA Metabolomics Facility (https://www.biocampus.cnrs.fr/index.php/en/facilities-en/browse-by-facility/platform/427-mamma)

Invited lecturer at the Gunma University, Initiative for Advanced Research, Japan (GIAR)  (https://www.giar.gunma-u.ac.jp/eng/member/turtoi-andrei/)

Member of the American Society for Investigative Pathology (https://www.asip.org/membership-community/scientific-interest-groups/molecular-diagnostic-pathology/)

Sophie Pattingre, PhD, HDR, Inserm

Keywords: Autophagy, Mitophagy, Signalisation, Cell Biology, Biochemistry

Memberships in learned societies: President of CFATG 2019-2024, Founding member of WIA (Women in Autophagy), Faculty advisor of the WIA fundraising committee (2020-2023), Co-chair WIA 2024, Chair WIA 2025

Marie-Alix Poul, Professor, University of Montpellier

Key words: Antibody Engineering, Immunotherapy, Antibody Phage Display, Yeast Display

Head of the Cancer Biology Masters, University of Montpellier, year 1 (https://masterbs.edu.umontpellier.fr/les-parcours/cancer-biology/).

Part of the canceropole GSO Axis 3 comitee  https://www.canceropole-gso.org/page/les-5-axes/10-axe-3-innovation-therapeutique-et-biomarqueurs.html

Funding : European Union, ANR, Labex MABimprove, Région Occitanie prématuration, Cancéropôle GSO, La Ligue contre le Cancer.