SQSTM1/p62 as a therapeutic target in cancer

Cell survival depends on dynamic interactions among the signaling pathways that control the endoplasmic reticulum (ER) stress response, macroautophagy/autophagy and apoptotic cell death. Our recent study reported an association of cytoplasmic SQSTM1/p62-mediated autophagy with disease progression and therapy resistance in head and neck squamous cell carcinoma (HNSCC). Synthetic small molecule ligands of SQSTM1 activate autophagic flux by binding the SQSTM1 ZZ domain and promoting self-oligomerization. Importantly, we found that the combination of pharmacological activation of SQSTM1 and therapeutic radiation promotes formation of ubiquitinated CASP8 (caspase 8) aggresomes that lead to apoptotic cell death of HNSCC. This finding suggests the potential for the development of a novel therapeutic strategy involving pharmacological activation of SQSTM1 in intrinsically apoptosis-resistant and therapy-resistant cancer cells.