Arylsulfatase D promotes malignant phenotypes in glioblastoma cells and is linked to altered Hippo pathway phosphorylation.

Introduction: Glioblastoma (GBM) is a highly aggressive malignant brain tumor with persistently poor clinical outcomes and few effective treatment options. Arylsulfatase D (ARSD), a lysosomal sulfatase implicated in several cancers, has not been fully characterized in GBM. Methods: ARSD expression in GBM was evaluated using bioinformatic analyses and immunohistochemical validation. ARSD was overexpressed or knocked down in U87MG, U251MG, and A172 cells, and proliferation, three-dimensional spheroid growth, apoptosis, invasion, and Matrigel-based tube-like network formation were assessed. Merlin/LATS/YAP phosphorylation-related protein patterns were analyzed. Irosustat was further evaluated in a subcutaneous U87MG xenograft model. Results: ARSD was upregulated in GBM tissues, and higher ARSD expression was associated with unfavorable patient survival. ARSD overexpression enhanced proliferation, three-dimensional spheroid growth, invasion, and Matrigel-based tube-like network formation while reducing apoptosis, whereas ARSD knockdown suppressed these malignant phenotypes. ARSD expression was associated with altered Merlin/LATS/YAP phosphorylation-related protein patterns, particularly changes in YAP1 abundance and phosphorylation status. In the xenograft model, Irosustat treatment altered YAP phosphorylation-associated protein patterns, enhanced tumor cell apoptosis, reduced tumor burden, and prolonged mouse survival. Discussion: These findings indicate that ARSD facilitates GBM malignant behavior and is linked to Merlin/LATS/YAP phosphorylation-related signaling. Irosustat showed preliminary antitumor activity in the xenograft model; however, because Irosustat is not an ARSD-specific inhibitor, the in vivo findings should not be interpreted as evidence of selective ARSD inhibition.