Supplementary Figure S8 from PlexinB1 Inactivation Reprograms Immune Cells in the Tumor Microenvironment, Inhibiting Breast Cancer Growth and Metastatic Dissemination
posted on 2024-09-03, 07:20authored byGiulia Franzolin, Serena Brundu, Carina F. Cojocaru, Aurora Curatolo, Matteo Ponzo, Roberta Mastrantonio, Emiko Mihara, Atsushi Kumanogoh, Hiroaki Suga, Junichi Takagi, Luca Tamagnone, Enrico Giraudo
PLXNB1 inhibition did not directly affect tumor cells both in vitro and in vivo in EMT6 TNBC mouse model
Funding
Fondazione AIRC per la ricerca sul cancro ETS (AIRC)
Fondazione del Piemonte per L'Oncologia (FPRC)
Ministero della Salute (Italy Ministry of Health)
Università Cattolica del Sacro Cuore (UCSC)
Japan Agency for Medical Research and Development (AMED)
History
ARTICLE ABSTRACT
Semaphorin–plexin signaling plays a major role in the tumor microenvironment (TME). In particular, Semaphorin 4D (SEMA4D) has been shown to promote tumor growth and metastasis; however, the role of its high-affinity receptor Plexin-B1 (PLXNB1), which is expressed in the TME, is poorly understood. In this study, we directly targeted PLXNB1 in the TME of triple-negative murine breast carcinoma to elucidate its relevance in cancer progression. We found that primary tumor growth and metastatic dissemination were strongly reduced in PLXNB1-deficient mice, which showed longer survival. PLXNB1 loss in the TME induced a switch in the polarization of tumor-associated macrophages (TAM) toward a pro-inflammatory M1 phenotype and enhanced the infiltration of CD8+ T lymphocytes both in primary tumors and in distant metastases. Moreover, PLXNB1 deficiency promoted a shift in the Th1/Th2 balance of the T-cell population and an antitumor gene signature, with the upregulation of Icos, Perforin-1, Stat3, and Ccl5 in tumor-infiltrating lymphocytes (TILs). We thus tested the translational relevance of TME reprogramming driven by PLXNB1 inactivation for responsiveness to immunotherapy. Indeed, in the absence of PLXNB1, the efficacy of anti-PD-1 blockade was strongly enhanced, efficiently reducing tumor growth and distant metastasis. Consistent with this, pharmacological PLXNB1 blockade by systemic treatment with a specific inhibitor significantly hampered breast cancer growth and enhanced the antitumor activity of the anti-PD-1 treatment in a preclinical model. Altogether, these data indicate that PLXNB1 signaling controls the antitumor immune response in the TME and highlight this receptor as a promising immune therapeutic target for metastatic breast cancers.