p62/SQSTM1 in cancer: phenomena, mechanisms, and regulation in DNA damage repair

The multidomain protein cargo adaptor p62, also known as sequestosome 1, serves as a shuttling factor and adaptor for the degradation of substrates via the proteasome and autophagy pathways. Regarding its structure, p62 is composed of several functional domains, including the N-terminal Phox1 and Bem1p domains, a ZZ-type zinc finger domain, a LIM protein-binding domain that contains the tumor necrosis factor receptor-associated factor 6 (TRAF6) binding region, two nuclear localization signals (NLS 1/2), a nuclear export signal (NES), the LC3-interacting region (LIR), a Kelch-like ECH-associated protein 1 (KEAP1)-interacting region, and a ubiquitin-associated (UBA) domain. Recent studies have highlighted the critical role of p62 in the development and progression of various malignancies. Overexpression and/or impaired degradation of p62 are linked to the initiation and progression of numerous cancers. While p62 is primarily localized in the cytosol and often considered a cytoplasmic protein, most of the existing literature focuses on its cytoplasmic functions, leaving its nuclear roles less explored. However, an increasing body of research has uncovered p62's involvement in the cellular response to DNA damage. In this review, we summarize the current understanding of p62's molecular functions in malignancies, with particular emphasis on its role in DNA damage repair, highlighting the latest advances in this field.