CTSL inhibitors(The University of Sydney)

Cathepsin L (CTSL), a cysteine cathepsin protease of the papain superfamily, plays a crucial role in cancer progression and metastasis. Dysregulation of CTSL is frequently observed in tumor malignancies, leading to the degradation of extracellular matrix and facilitating epithelial-mesenchymal transition (EMT), a key process in malignant cancer metastasis. This review mainly provides a comprehensive information about recent findings on natural inhibitors targeting CTSL and their anticancer effects, which have emerged as potent anticancer therapeutic agents or metastasis-suppressive adjuvants. Specifically, inhibitors are categorized into small-molecule and macromolecule inhibitors, with a particular emphasis on cathepsin propeptide-type macromolecules. Additionally, the article explores the molecular mechanisms of CTSL involvement in cancer metastasis, highlighting its regulation at transcriptional, translational, post-translational, and epigenetic levels. This work underscores the importance of understanding natural CTSL inhibitors and provides researchers with practical insights to advance the relevant fields and discover novel CTSL-targeting inhibitors from natural sources.

Age‐related declines in oocyte quality and ovarian function are pivotal contributors to female subfertility in clinical settings. Yet, the mechanisms driving ovarian aging and oocyte senescence remain inadequately understood. The present study evaluated the alterations in N‐glycoproteins associated with ovarian aging and noted a pronounced elevation in N221 glycopeptides of cathepsin L (Ctsl) in the ovaries of reproductive‐aged mice (8–9 months and 11–12 months) compared to younger counterparts (6–8 weeks). Subsequent analysis examined the involvement of Ctsl in oocyte aging and demonstrated a significant elevation in Ctsl levels in aged oocytes. Further, it was revealed that the overexpression of Ctsl in young oocytes substantially diminished their quality, while oocytes expressing an N221‐glycosylation mutant of Ctsl did not suffer similar quality degradation. This finding implies that the N221 glycosylation of Ctsl is pivotal in modulating its effect on oocyte health. The introduction of a Ctsl inhibitor into the culture medium restored oocyte quality in aged oocytes by enhancing mitochondrial function, reducing accumulated reactive oxygen species (ROS), lowering apoptosis, and recovering lysosome capacity. Furthermore, the targeted downregulation of Ctsl using siRNA microinjection in aged oocytes enhanced fertilization capability and blastocyst formation, affirming the role of Ctsl knockdown in fostering oocyte quality and embryonic developmental potential. In conclusion, these findings underscore the detrimental effects of high expression of N‐glycosylated Ctsl on oocyte quality and its contribution to oocyte senescence, highlighting it as a potential therapeutic target to delay ovarian aging and enhance oocyte viability.