FHL1 INTERACTS WITH SP1 TO REGULATE EGFR EXPRESSION IN GLIOBLASTOMA

Abstract The four and a half LIM domain 1 (FHL1) has been considered as a tumor suppressor protein in multiple cancers. Here, we show that FHL1 plays a tumor-promoting role in glioblastoma, the most common and incurable brain cancer. Overexpression of FHL1 promotes the growth, migration, and invasion of GBM cells in vivo and in vitro. In contrast, FHL1 silencing exhibits the opposite effects. Mechanically, FHL1 upregulates EGFR expression and activates the downstream AKT / ERK1 / 2 / STAT3 signaling pathways. We further demonstrated that SP1 can also be induced by FHL1 expression, and FHL1 interacts with SP1 to upregulate EGFR expression at both mRNA and protein levels, leading to glioblastoma malignancy. Clinically, FHL1 is highly expressed in glioblastoma and shows positive correlation with EGFR and SP1 in GBM specimens. Our results suggest the key role of FHL1 in the expression of EGFR and highlight the translation potential of inhibiting FHL1 as a treatment for glioblastoma.