Centro Interdipartimentale di Biotecnologie Molecolari "Guido Tarone"
Laura Conti PI
Associate Professor of Immunology (General Pathology), University of Turin, Italy.
Elisabetta Bolli Senior Postdoctoral Fellow
Antonino Di Lorenzo and Chiara Cossu Ph.D. Students
Irene Fiore Merighi Technician
Research activity
Breast cancer (BC) is the leading cause of cancer death in women. Despite early diagnosis and advancements in therapy, more than 30% of patients relapse, and 80% of BC deaths occur in patients who progressed to metastatic BC because of the development of primary or secondary resistance to therapy. Resistance to chemotherapy and immunotherapy can be attributed to several mechanisms, many of which rely on the complex crosstalk between cancer cells, immune cells, the tumor microenvironment and the microbiota. Cancer cells shape the tumor microenvironment in a pro-tumoral manner through several mechanisms, including by acquiring the expression and activation of molecules typically expressed by the innate immune system, such as Pattern-Recognition Receptors (PRRs). Physiologically, PRRs expressed by immune cells sense infections as well as tissue damage by binding to Pathogen-Associated Molecular Patterns (PAMPs) and Damage-Associated Molecular Patterns (DAMPs), respectively, and activate an inflammatory response. The expression of PRRs by tumor cells may promote tumor progression and resistance to therapies. By exploiting the pipeline developed in the OncoImmunology Lab to identify breast cancer-stem-cell (CSC) oncoantigens, we have discovered that BC cells express the PRR Toll-like Receptor (TLR)2 and demonstrated that TLR2 is activated by DAMPs released by cancer cells, either actively or following chemotherapy-induced cell death. By generating TLR2KO and TLR2WT ErbB2-transgenic mice, which spontaneously develop mammary cancer, and using several other BC models, we showed that TLR2 activation promotes CSC self-renewal through the activation of the MyD88/NF-kB pathway, fostering BC cell survival, metastasis and drug resistance. Moreover, TLR2 activation on immune cells induces T-regulatory-cell expansion and promotes immunosuppression. High expression of TLR2 is associated with poor prognoses and inferior responses to chemotherapy in BC patients, and we have demonstrated that the deletion or pharmacologic inhibition of TLR2 (using monoclonal antibodies or the CU-CPT-22 inhibitor) sensitizes BC cells to chemotherapy (Figure 1).
Since TLR2 also detects PAMPs, we are currently studying whether TLR2 functions as a bridge between BC cells and the local microbiota, and thus mediates the detrimental effects that dysbiosis may exert on tumor response to chemotherapy.
A second line of research focuses on another PRR expressed by cancer cells; the stimulator of interferon genes (STING). Normally, the cyclic GMP-AMP synthase (cGAS)-STING pathway is activated by cytosolic double stranded DNA, released after tissue damage or viral infection, leading to the activation of the type I interferon (IFN) response, which recruits T lymphocytes. This may be a promising strategy to foster T cell tumor infiltration and turn cold tumors hot, possibly rendering BC responsive to immune checkpoint blockade (ICB) therapy. However, high levels of chromosomal instability and DNA damage lead to the altered activation of the cGAS-STING pathway in many BC, with the induction of a NF-kB-dependent inflammatory progression and resistance to therapy. Altered STING signaling in BC is associated with high rates of TP53 mutation, which blocks the canonical cGASSTING pathway, promoting the production of pro-tumoral cytokines via the activation of NF-kB (Figure 2).
We are currently studying the regulation of the cGAS-STING pathway in BC and developing combined therapies that can restore the activation of the STING-dependent IFN response, using STING agonists combined with re-activators of mutant P53 (such as APR-246) or other drugs, in combination with ICB.
We aim to further characterize the role of the TLR2 and STING pathways in the crosstalk between BC cells and the tumor microenvironment, including the tumor microbiota. In particular, to dissect the tumor-cell-intrinsic and immune-cell-mediated effects of these pathways. Moreover, we are characterizing the interaction between TLR2 and other CSC oncoantigens, such as the cystine-glutamate antiporter xCT, and developing theranostic nanoparticles to target tumor cells and for the intratumoral delivery of chemotherapy and TLR2 inhibitors. These nanosystems will be tested in combination with immunotherapies, including xCT-targeting vaccines developed by the OncoImmunology Lab. In parallel, we will evaluate new strategies for the reactivation of the canonical STING pathway (Figure 3).
Moreover, we are endeavoring to understand whether alterations in the tumor microbiota are responsible for TLR2-mediated chemoresistance and tumor progression by identifying the bacterial species involved in pro-tumoral and anti-tumoral effects during treatment, and to identify possible correlations between the composition of the mammary microbiota, tumor stemness and the clinical response to chemotherapy. This information will be helpful for patient stratification, while the design of innovative approaches for microbiota manipulation would ameliorate the prognosis of patients who do not currently respond to chemotherapy.
2022-2027: Investigator Grant, Fondazione AIRC per la Ricerca (AIRC IG 2021; ID 25766).
2022-2024: Fondazione CRT, RF 2021.1774.
2016-2019: Ministero della Salute, bando progetti di ricerca giovani ricercatori, rf-2013-02354892
Park SC*, Conti L*, Franceschi V, Oh BK, Yang MS, Ham G, Di Lorenzo A, Bolli E, Cavallo F, Kim B, Donofrio G. Assessment of BoHV-4-based vector vaccine intranasally administered in a hamster challenge model of lung disease. Frontiers in Immunology. 2023. *Equal contribution. Doi: 10.3389/fmmu.2023.1197649.
Di Gregorio E, Romiti C, Di Lorenzo A, Cavallo F, Ferrauto G, Conti L. RGD_PLGA Nanoparticles with Docetaxel: A Route for Improving Drug Efficiency and Reducing Toxicity in Breast Cancer Treatment. Cancers (Basel). 2022;15(1):8. Doi: 10.3390/cancers15010008.
Di Lorenzo A, Bolli E, Ruiu R, Ferrauto G, Di Gregorio E, Avalle L, Savino A, Poggio P, Merighi IF, Riccardo F, Brancaccio M, Quaglino E, Cavallo F, Conti L. Tolllike receptor 2 promotes breast cancer progression and resistance to chemotherapy. Oncoimmunology. 2022;2086752. Doi: 10.1080/2162402X.2022.2086752.
Ruiu R, Di Lorenzo A, Cavallo F, Conti L. Are Cancer Stem Cells a suitable target for breast cancer immunotherapy? Frontiers in Oncology. 2022; Vol. 12. Doi: 10.3389/fonc.2022.877384.
Di Lorenzo A, Bolli E, Tarone L, Cavallo F, Conti L. Toll-Like Receptor 2 at the Crossroad between Cancer Cells, the Immune System, and the Microbiota. Int. J. Mol. Sci. 2020; 21(24), 9418. Doi: 10.3390/ ijms21249418.
Salemme V, Centonze G, Cavallo F, Deflippi P, Conti L. The crosstalk between tumor cells and the immune microenvironment in breast cancer: implications for immunotherapy. Frontiers in Oncology. 2021; 11:610303. Doi: 10.3389/fonc.2021.610303.
Conti L, Franceschi V, Macchi F, Riccardo F, Ruiu R, Russo L; Quaglino E, Donofrio G, Cavallo F. Immunotargeting of the xCT cystine/glutamate antiporter potentiates the eficacy of Her2-targeted immunotherapies in breast cancer. Cancer Immunol Res. 2020; 8(8), 1039-1053. Doi: 10.1158/2326-6066.CIR-20-0082.
Ruiu R, Rolih V, Bolli E, Barutello G, Riccardo F, Quaglino E, Merighi IF, Pericle F, Donofrio G, Cavallo F, Conti L. Fighting breast cancer stem cells through the immune-targeting of the xCT cystine-glutamate antiporter. Cancer Immunol Immunother. 2019; 68(1):131- 141. Doi: 10.1158/2326-6066.CIR-20-0082.
Donofrio G, Tebaldi G, Lanzardo S, Ruiu R, Bolli E, Ballatore A, Rolih V, Macchi F, Conti L*, Cavallo F*. Bovine herpesvirus 4-based vector delivering the full length xCT DNA efficiently protects mice from mammary cancer metastases by targeting cancer stem cells. Oncoimmunology. 2018; 7(12):e1494108. *Equal contribution. Doi: 10.1080/2162402X.2018.1494108.
Conti L, Lanzardo S, Arigoni M, Antonazzo R, Radaelli E, Cantarella D, Calogero RA, Cavallo F. The non-inflammatory role of High mobility group box 1/Toll-like Receptor 2 axis in the self-renewal of mammary cancer stem cells. FASEB Journal. 2013; 27:4731-44. Doi: 10.1096/fj.13-230201.
