Z-FL-COCHO, a cathepsin S inhibitor, enhances oxaliplatin-induced apoptosis through upregulation of Bim expression

Lysosomal peptidases – Intriguing roles in cancer progression and neurodegeneration

Lysosomal peptidases are hydrolytic enzymes capable of digesting waste proteins that are targeted to lysosomes via endocytosis and autophagy. Besides intracellular protein catabolism, they play more specific roles in several other cellular processes and pathologies, either within lysosomes, upon secretion into the cell cytoplasm or extracellular space, or bound to the plasma membrane. In cancer, lysosomal peptidases are generally associated with disease progression, as they participate in crucial processes leading to changes in cell morphology, signaling, migration, and invasion, and finally metastasis. However, they can also enhance the mechanisms resulting in cancer regression, such as apoptosis of tumor cells or antitumor immune responses. Lysosomal peptidases have also been identified as hallmarks of aging and neurodegeneration, playing roles in oxidative stress, mitochondrial dysfunction, abnormal intercellular communication, dysregulated trafficking, and the deposition of protein aggregates in neuronal cells. Furthermore, deficiencies in lysosomal peptidases may result in other pathological states, such as lysosomal storage disease. The aim of this review was to highlight the role of lysosomal peptidases in particular pathological processes of cancer and neurodegeneration and to address the potential of lysosomal peptidases in diagnosing and treating patients.

Role of protein phosphatase 2A in kidney disease (Review)

Kidney disease affects millions of people worldwide and is a financial burden on the healthcare system. Protein phosphatase 2A (PP2A), which is involved in renal development and the function of ion-transport proteins, aquaporin-2 and podocytes, is likely to serve an important role in renal processes. PP2A is associated with the pathogenesis of a variety of different kidney diseases including podocyte injury, inflammation, tumors and chronic kidney disease. The current review aimed to discuss the structure and function of PP2A subunits in the context of kidney diseases. How dysregulation of PP2A in the kidneys causes podocyte death and the inactivation of PP2A in renal carcinoma tissues is discussed. Inhibition of PP2A activity prevents epithelial-mesenchymal transition and attenuates renal fibrosis, creating a favorable inflammatory microenvironment and promoting the initiation and progression of tumor pathogenesis. The current review also indicates that PP2A serves an important role in protection against renal inflammation. Understanding the detailed mechanisms of PP2A provides information that can be utilized in the design and application of novel therapeutics for the treatment and prevention of renal diseases.

miR-193a-5p as a promising therapeutic candidate in colorectal cancer by reducing 5-FU and Oxaliplatin chemoresistance by targeting CXCR4

Colorectal cancer (CRC) is one of the most common causes of cancer-related deaths worldwide. The role of microRNAs (miRNAs/miRs) as small (19-25 nucleotides in length) non-coding RNA molecules that modify gene expression has been shown in several types of cancer. 5-Fluorouracil (5-FU) and oxaliplatin (Ox) are two common chemotherapeutic agents used to treat cancer. The present study aimed to evaluate the expression levels of miR-193a-5p in CRC, and its effect on the C-X-C Motif Chemokine Receptor 4 (CXCR4) target gene alone and in combination with chemotherapeutic drugs, to determine its possible role in chemoresistance. CRC tissues and adjacent non-cancerous tissue were obtained from 67 patients who had undergone surgery to determine the expression levels of miR-193a-5p and CXCR4. Subsequently, qPCR and Western blotting were performed to determine the effect of miR-193a-5p and chemotherapy drugs on CXCR4. َAlso, MTT assay, and flow cytometry was performed to determine their role in cell viability and apoptosis. Besides, the relationship between miR-193a-5p and CXCR4 with patients' clinical features was investigated. The results of the present study showed that miR-193a-5p was significantly downregulated, whereas CXCR4 was significantly upregulated in tumor tissues obtained from patients with CRC compared with the adjacent non-tumor healthy controls. In addition, the upregulation of miR-193-5p reduced the expression levels of CXCR4, particularly in combination with 5-FU and OX. Besides, using rescue experiments, the present study showed that miR-193a-5p replacement was able to suppress CXCR4-induced CRC cell proliferation by directly targeting CXCR4. Furthermore, there was a significant association between miR-193a-5p and CXCR4 with certain clinicopathological characteristics, particularly with metastasis-related features. These results suggest that miR-193a-5p serves a tumor-suppressive function in CRC and can directly target CXCR4 and decrease its mRNA and protein expression levels. Additionally, miR-193a-5p in combination with 5-FU and Ox potentiated reducing CXR4 expression, which may reveal its contribution to tumor chemoresistance. In conclusion, miR-193-5p may be applicable as a prognostic and diagnostic marker, and also serve as a therapeutic factor by reducing CXCR4 in combination with chemotherapeutic drugs.

Cathepsin S Regulates Antigen Processing and T Cell Activity in Non-Hodgkin Lymphoma

Genomic alterations in cancer cells can influence the immune system to favor tumor growth. In non-Hodgkin lymphoma, physiological interactions between B cells and the germinal center microenvironment are coopted to sustain cancer cell proliferation. We found that follicular lymphoma patients harbor a recurrent hotspot mutation targeting tyrosine 132 (Y132D) in cathepsin S (CTSS) that enhances protein activity. CTSS regulates antigen processing and CD4⁺ and CD8⁺ T cell-mediated immune responses. Loss of CTSS activity reduces lymphoma growth by limiting communication with CD4⁺ T follicular helper cells while inducing antigen diversification and activation of CD8⁺ T cells. Overall, our results suggest that CTSS inhibition has non-redundant therapeutic potential to enhance anti-tumor immune responses in indolent and aggressive lymphomas.

Melatonin attenuates epidermal growth factor-induced cathepsin S expression in ARPE-19 cells: Implications for proliferative vitreoretinopathy

Abnormal proliferation and motility of retinal pigment epithelial cells leads to proliferative vitreoretinopathy (PVR). Melatonin is a known effective antitumour and anti-invasive agent, but whether it affects the formation and underlying mechanisms of PVR remains unclear. In this study, the results of the MTT assay, colony formation and propidium iodide (PI) staining with flow cytometry revealed that melatonin dose dependently inhibited epidermal growth factor (EGF)-induced proliferation of human ARPE-19 cells. Furthermore, melatonin reduced EGF-induced motility by suppressing cathepsin S (CTSS) expression. Pretreatment with ZFL (a CTSS inhibitor) or overexpression of CTSS (pCMV-CTSS) significantly inhibited EGF-induced cell motility when combined with melatonin. Epidermal growth factor induced the phosphorylation of AKT(S473)/mTOR (S2448) and transcription factor (c-Jun/Sp1) signaling pathways. Pretreatment of LY294002 (a PI3K inhibitor) or rapamycin (an mTOR inhibitor) markedly reduced EGF-induced motility and p-AKT/p-mTOR/c-Jun/Sp1 expression when combined with melatonin. Taken together, these data indicate that melatonin inhibited EGF-induced proliferation and motility of human ARPE-19 cells by activating the AKT/mTOR pathway, which is dependent on CTSS modulation of c-Jun/Sp1 signalling. Melatonin may be a promising therapeutic drug against PVR.

Cathepsin K inhibition-induced mitochondrial ROS enhances sensitivity of cancer cells to anti-cancer drugs through USP27x-mediated Bim protein stabilization

Cathepsin K (Cat K) is expressed in cancer cells, but the effect of Cat K on apoptosis is still elusive. Here, we showed that inhibition of Cat K sensitized the human carcinoma cells to anti-cancer drug through up-regulation of Bim. Inhibition of Cat K increased USP27x expression, and knock down of USP27x markedly blocked Cat K-induced up-regulation of Bim expression. Furthermore, inhibition of Cat K induced proteasome-dependent degradation of regulatory associated protein of mammalian target of rapamycin (Raptor). Down-regulation of Raptor expression increased mitochondrial ROS production, and mitochondria specific superoxide scavengers prevented USP27x-mediated stabilization of Bim by inhibition of Cat K. Moreover, combined treatment with Cat K inhibitor (odanacatib) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) reduced tumor growth and induced cell death in a xenograft model. Our results demonstrate that Cat K inhibition enhances anti-cancer drug sensitivity through USP27x-mediated the up-regulation of Bim via the down-regulation of Raptor.

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Inhibition of Cat K sensitizes cancer cells to anti-cancer drugs.

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Reduction of Raptor by inhibition of Cat K induces mitochondria dysfunction.

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Mitochondrial ROS induction by inhibition of Cat K induces USP27X expression.

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Up-regulation of USP27X by inhibition of Cat K stabilizes Bim protein.

Inhibition of FOXO3a/BIM signaling pathway contributes to the protective effect of salvianolic acid A against cerebral ischemia/reperfusion injury

Salvianolic acid A (SalA) is an effective compound extracted from traditional Chinese medicine Salvia miltiorrhiza Bunge. The Forkhead box O3a (FOXO3a) signaling pathway plays crucial roles in the modulation of ischemia-induced cell apoptosis. However, no information about the regulatory effect of SalA on FoxO3a is available. To explore the anti-cerebral ischemia effect and clarify the therapeutic mechanism of SalA, SH-SY5Y cells and Sprague–Dawley rats were applied, which were exposed to oxygen glucose deprivation/reoxygenation (OGD/R) and middle cerebral artery occlusion/reperfusion (MCAO/R) injuries, respectively. The involved pathway was identified using the specific inhibitor LY294002. Results showed that SalA concentration-dependently inhibited OGD/R injury triggered cell viability loss. SalA reduced cerebral infarction, lowered brain edema, improved neurological function, and inhibited neuron apoptosis in MCAO/R rats, which were attenuated by the treatment of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) specific inhibitor LY294002. SalA time- and concentration-dependently upregulated the phosphorylation levels of protein kinase B (AKT) and its downstream protein FOXO3a. Moreover, the nuclear translocation of FOXO3a was inhibited by SalA both in vivo and in vitro, which was also reversed by LY294002. The above results indicated that SalA fought against ischemia/reperfusion damage at least partially via the AKT/FOXO3a/BIM pathway.

Cathepsins: Potent regulators in carcinogenesis

Cathepsins (CTS) are mainly lysosomal acid hydrolases extensively involved in the prognosis of different diseases, and having a distinct role in tumor progression by regulating cell proliferation, autophagy, angiogenesis, invasion, and metastasis. As all these processes conjunctively lead to cancer progression, their site-specific regulation might be beneficial for cancer treatment. CTS regulate activation of the proteolytic cascade and protein turnover, while extracellular CTS is involved in promoting extracellular matrix degradation and angiogenesis, thereby stimulating invasion and metastasis. Despite cancer regulation, the involvement of CTS in cellular adaptation toward chemotherapy and radiotherapy augments their therapeutic potential. However, lysosomal permeabilization mediated cytosolic translocation of CTS induces programmed cell death. This complex behavior of CTS generates the need to discuss the different aspects of CTS associated with cancer regulation. In this review, we mainly focused on the significance of each cathepsin in cancer signaling and their targeting which would provide noteworthy information in the context of cancer biology and therapeutics.