Proguanil inhibits proliferation and migration in glioblastoma development through targeting CSF1R receptor

Glioblastoma (GBM) is the most common and aggressive malignant tumor of the central nervous system, characterized by high morbidity and invasive potential, necessitating urgent development of novel therapeutic strategies. Studies have shown that colony stimulating factor-1 receptor (CSF1R) is abnormally expressed in a variety of solid tumors, which is closely related to the development of tumor cells. In this study, the CSF1R/cell membrane Chromatographic model was successfully constructed, and was used to screen active compounds targeting CSF1R from more than 60 compounds. Among these, Proguanil exhibited the strongest affinity with retention time of 69 min, and a K_D value of (6.73 ± 0.05) × 10^-7 M. Proguanil effectively inhibited the growth of U87MG cells in vitro and in vivo by inducing G0/G1 phase cell cycle arrest and suppressing U87MG cells migration. More importantly, we found that Proguanil's inhibitory effect on U87MG cell growth and migration was positively correlated with CSF1R expression, and this effect diminished following CSF1R knockdown and Proguanil demonstrated synergistic effects with CSF1R-targeting positive drugs (BLZ945 and GW2580). Furthermore, Proguanil was found to inhibit CSF1R phosphorylation along with downstream signaling pathways such as PTEN/AKT/mTOR and Ras/MEK1/2/ERK1/2, thereby regulating cell cycle-related molecules (p21, CDK4, and CyclinD1) and cell migration-related molecule MMP3. Meanwhile, Proguanil targeted CSF1R to inhibit M2-type polarization of tumor-associated macrophages (TAMs) and their proliferation, thus altering the tumor microenvironment while indirectly suppressing the proliferation and migration of U87MG cells. Taken together, these findings suggest that Proguanil may serve as a promising CSF1R antagonist for GBM treatment.