Work

Induction of Ca2+-dependent autophagy and concurrent lysosomal alkalinization underlies the cytotoxic effects of NNC-55–0396 on glioblastoma cells

Year: 2024

Type: article

Abstract: Diverse agents targeting (macro)autophagy, a critical metabolic stress response in cancer cells, have been proposed for cancer therapy. In previous studies, we showed that NNC-55–0396 (NNC) induces glioblastoma cell death by activating the Unfolded Protein Response (UPR) of ER stress and increasing cytosolic Ca 2+ levels. Here, we report that NNC affects both ends of the autophagy process, causing extensive cytoplasmic vacuolation. Our results show that: (1) NNC induces autophagy downstream of UPR and Ca 2+ signaling pathways, thus silencing IRE1α/JNK1 or inhibiting Ca 2+ /IP 3 R signaling prevents NNC-induced vacuolation. (2) Silencing ATG5 delays cell death, indicating that autophagy induction plays a role in NNC's cytotoxic effects. (3) NNC and other Ca 2+ -mobilizing agents transcriptionally upregulate p62/SQSTM1, an autophagosome cargo receptor, highlighting a role for this protein in the response to NNC. (4) Studies using tandem fluorescent-tagged LC3 and electron microscopy, however, further reveal that NNC blocks late-stage autophagy that leads to enlarged degradative compartments accumulating ubiquitin-tagged cargoes. (5) Finally, NNC impedes pro-cathepsin-B processing, an effect that is reversed with a weak acid co-treatment, suggesting that lysosomal dysfunction due to increased intraluminal pH is the underlying cause of the autophagy blockade. Together, these findings underscore a multi-level dysregulation of autophagy that contributes to NNC's anti-tumoral effects. • Tetralin derivative NNC-55–0396 exerts cytotoxic effects in glioblastoma cells. • NNC-55–0396 causes cytoplasmic vacuolation, resulting from a concomitant induction and block of autophagy. • NNC-55–0396 induces autophagy by promoting ER Ca 2+ mobilization and IRE1α/JNK1 ER-stress activation. • NNC-55–0396 blocks autophagy flux by preventing cathepsin B maturation.

Source: Biomedicine & Pharmacotherapy

DOI: 10.1016/j.biopha.2024.117690

Authors: Anna Visa, Maria Casals, Lía Alza, Judit Herreros, Carles Cantí

Institutions: Universitat de Lleida, Instituto de Investigación Biomédica de Lleida

Language: English

Topic: Autophagy in Disease and Therapy

Subfield: Epidemiology

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,420