Monocyte-derived glioma-associated macrophages are the largest infiltrating immune cell population in glioblastomas and act to facilitate gliomagenesis. In a study reported in the Journal of the National Cancer Institute, Xu and colleagues assessed the effect of microRNA (miR)-142-3p on proinflammatory M1 and immunosuppressive M2 macrophages in a murine glioblastoma model.
miR-142-3p was the most downregulated miRNA (approximately 4.95-fold) in glioblastoma-infiltrating macrophages, and miR-142-3p expression was lower in M2 macrophages vs M1 macrophages (P = .03). Overexpression of miR-142-3p in M2 macrophages resulted in selective modulation of transforming growth factor beta receptor 1 and subsequent preferential apoptosis in the M2 macrophage subset (P = .01). Administration of miR-142-3p resulted in inhibition of glioma growth (P = .03) and prolonged median survival (eg, 31 vs 23.5 days, P = .03, in immune-competent C57BL/6J mice) with an associated reduction in infiltrating macrophages.
The investigators concluded, “These data indicate a unique role of miR-142-3p in glioma immunity by modulating M2 macrophages through the transforming growth factor beta signaling pathway.” ■
Xu S, et al: J Natl Cancer Inst 106(8):dju162, 2014.