The multifaceted roles of nucleophagy in cancer development and therapy

Targeting selective autophagy and beyond: From underlying mechanisms to potential therapies

BACKGROUND

Autophagy is an evolutionarily conserved turnover process for intracellular substances in eukaryotes, relying on lysosomal (in animals) or vacuolar (in yeast and plants) mechanisms. In the past two decades, emerging evidence suggests that, under specific conditions, autophagy can target particular macromolecules or organelles for degradation, a process termed selective autophagy. Recently, accumulating studies have demonstrated that the abnormality of selective autophagy is closely associated with the occurrence and progression of many human diseases, including neurodegenerative diseases, cancers, metabolic diseases, and cardiovascular diseases.

AIM OF REVIEW

This review aims at systematically and comprehensively introducing selective autophagy and its role in various diseases, while unravelling the molecular mechanisms of selective autophagy. By providing a theoretical basis for the development of related small-molecule drugs as well as treating related human diseases, this review seeks to contribute to the understanding of selective autophagy and its therapeutic potential.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we systematically introduce and dissect the major categories of selective autophagy that have been discovered. We also focus on recent advances in understanding the molecular mechanisms underlying both classical and non-classical selective autophagy. Moreover, the current situation of small-molecule drugs targeting different types of selective autophagy is further summarized, providing valuable insights into the discovery of more candidate small-molecule drugs targeting selective autophagy in the future. On the other hand, we also reveal clinically relevant implementations that are potentially related to selective autophagy, such as predictive approaches and treatments tailored to individual patients.

Cisplatin-induced cell death increases the degradation of the MRE11-RAD50-NBS1 complex through the autophagy/lysosomal pathway

Cisplatin and other platinum-based anticancer agents are among the most widely used chemotherapy drugs in the treatment of different types of cancer. However, it is common to find patients who respond well to treatment at first but later relapse due to the appearance of resistance to cisplatin. Among the mechanisms responsible for this phenomenon is the increase in DNA damage repair. Here, we elucidate the effect of cisplatin on the MRN (MRE11-RAD50-NBS1) DNA damage sensor complex. We found that the tumor suppressor FBXW7 is a key factor in controlling the turnover of the MRN complex by inducing its degradation through lysosomes. Inhibition of lysosomal enzymes allowed the detection of the association of FBXW7-dependent ubiquitylated MRN with LC3 and the autophagy adaptor p62/SQSTM1 and the localization of MRN in lysosomes. Furthermore, cisplatin-induced cell death increased MRN degradation, suggesting that this complex is one of the targets that favor cell death. These findings open the possibility of using the induction of the degradation of the MRN complex after genotoxic damage as a potential therapeutic strategy to eliminate tumor cells.

Autophagy Modulators in Cancer Therapy

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.