AUTHOR=Massenzio Francesca , Cambiaghi Marco , Marchiotto Federica , Boriero Diana , Limatola Cristina , D’Alessandro Giuseppina , Buffelli Mario TITLE=In vivo morphological alterations of TAMs during KCa3.1 inhibition—by using in vivo two-photon time-lapse technology JOURNAL=Frontiers in Cellular Neuroscience VOLUME=16 YEAR=2022 URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2022.1002487 DOI=10.3389/fncel.2022.1002487 ISSN=1662-5102 ABSTRACT=

Tumor associated macrophages (TAMs) are the mostprevalent cells recruited in the tumor microenvironment (TME). Once recruited, TAMs acquire a pro-tumor phenotype characterized by a typical morphology: ameboid in the tumor core and with larger soma and thick branches in the tumor periphery. Targeting TAMs by reverting them to an anti-tumor phenotype is a promising strategy for cancer immunotherapy. Taking advantage of Cx3cr1GFP/WT heterozygous mice implanted with murine glioma GL261-RFP cells we investigated the role of Ca2+-activated K+ channel (KCa3.1) on the phenotypic shift of TAMs at the late stage of glioma growth through in vivo two-photon imaging. We demonstrated that TAMs respond promptly to KCa3.1 inhibition using a selective inhibitor of the channel (TRAM-34) in a time-dependent manner by boosting ramified projections attributable to a less hypertrophic phenotype in the tumor core. We also revealed a selective effect of drug treatment by reducing both glioma cells and TAMs in the tumor core with no interference with surrounding cells. Taken together, our data indicate a TRAM-34-dependent progressive morphological transformation of TAMs toward a ramified and anti-tumor phenotype, suggesting that the timing of KCa3.1 inhibition is a key point to allow beneficial effects on TAMs.