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Cysteine cathepsins are lysosomal proteases subject to dynamic regulation within antigen‐presenting cells during the immune response and associated diseases. To investigate the regulation of cathepsin X, a carboxy‐mono‐exopeptidase, during maturation of dendritic cells (DCs), we exposed immortalized mouse DCs to various Toll‐like receptor agonists. Using a cathepsin X‐selective activity‐based probe, sCy5‐Nle‐SY, we observed a significant increase in cathepsin X activation upon TLR‐9 agonism with CpG, and to a lesser extent with Pam3 (TLR1/2), FSL‐1 (TLR2/6) and LPS (TLR4). Despite clear maturation of DCs in response to Poly I:C (TLR3), cathepsin X activity was only slightly increased by this agonist, suggesting differential regulation of cathepsin X downstream of TLR activation. We demonstrated that cathepsin X was upregulated at the transcriptional level in response to CpG. This occurred at late time points and was not dampened by NF‐κB inhibition. Factors secreted from CpG‐treated cells were able to provoke cathepsin X upregulation when applied to naïve cells. Among these factors was IL‐6, which on its own was sufficient to induce transcriptional upregulation and activation of cathepsin X. IL‐6 is highly secreted by DCs in response to CpG but much less so in response to poly I:C, and inhibition of the IL‐6 receptor subunit glycoprotein 130 prevented CpG‐mediated cathepsin X upregulation. Collectively, these results demonstrate that cathepsin X is differentially transcribed during DC maturation in response to diverse stimuli, and that secreted IL‐6 is critical for its dynamic regulation. [ABSTRACT FROM AUTHOR]

Simple Summary: Oral cancer is often deadly and severely painful. Because this form of cancer pain cannot be adequately treated with current medications including opiates, new treatment approaches are needed. Cathepsin S, a lysosomal cysteine protease may play a role in oral cancer pain through a protease-activated receptor-2 (PAR2)-dependent mechanism. We undertook a series of experiments to define the role of cathepsin S in oral cancer pain. We compared cathepsin S activity in human oral cancer tumors versus patient-matched normal tissue; a human oral cancer cell line versus a benign dysplastic oral keratinocyte cell line; and in an orthotopic xenograft tongue cancer mouse model versus normal controls in mice. We localized cathepsin S in macrophages and carcinoma cells in human oral cancers. The injection of cathepsin S caused nociception in a mouse model while the injection of oral cancer cells in which the gene for cathepsin S is deleted generated less nociception. Our findings will lay the foundations for clinical trials of cathepsin S inhibitors for treating oral cancer pain. Oral squamous cell carcinoma (SCC) pain is more prevalent and severe than pain generated by any other form of cancer. We previously showed that protease-activated receptor-2 (PAR2) contributes to oral SCC pain. Cathepsin S is a lysosomal cysteine protease released during injury and disease that can activate PAR2. We report here a role for cathepsin S in PAR2-dependent cancer pain. We report that cathepsin S was more active in human oral SCC than matched normal tissue, and in an orthotopic xenograft tongue cancer model than normal tongue. The multiplex immunolocalization of cathepsin S in human oral cancers suggests that carcinoma and macrophages generate cathepsin S in the oral cancer microenvironment. After cheek or paw injection, cathepsin S evoked nociception in wild-type mice but not in mice lacking PAR2 in Nav1.8-positive neurons (Par2Nav1.8), nor in mice treated with LY3000328 or an endogenous cathepsin S inhibitor (cystatin C). The human oral SCC cell line (HSC-3) with homozygous deletion of the gene for cathepsin S (CTSS) with CRISPR/Cas9 provoked significantly less mechanical allodynia and thermal hyperalgesia, as did those treated with LY3000328, compared to the control cancer mice. Our results indicate that cathepsin S is activated in oral SCC, and that cathepsin S contributes to cancer pain through PAR2 on neurons. [ABSTRACT FROM AUTHOR]

Reports of mammary Paget's disease (MPD) as a manifestation of breast cancer recurrence are rare. MPD presents a particular challenge when emerging more than two decades after a breast cancer treated with evidence-based therapy. There is a broad spectrum of non-malignant causes for dermatitis of the nipple during the initial presentation that may delay cancer work-up. This case highlights the MPD work-up and management in the context of a personal history of breast cancer. This unique clinical presentation emphasizes the importance of vigilant cancer surveillance for timely intervention, especially for a presumed cured cancer., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Afzal et al.)