Inhibition of Cathepsin S Restores TGF-β-induced Epithelial-to-mesenchymal Transition and Tight Junction Turnover in Glioblastoma Cells

The effects of BMP2 and the mechanisms involved in the invasion and angiogenesis of IDH1 mutant glioma cells

PURPOSE

This study investigated the effect of an isocitrate dehydrogenase 1 (IDH1) mutation (mutIDH1) on the invasion and angiogenesis of human glioma cells.

METHODS

Doxycycline was used to induce the expression of mutIDH1 in glioma cells. Transwell and wound healing assays were conducted to assess glioma cell migration and invasion. Western blotting and cell immunofluorescence were used to measure the expression levels of various proteins. The influence of bone morphogenetic protein 2 (BMP2) on invasion, angiogenesis-related factors, BMP2-related receptor expression, and changes in Smad signaling pathway-related proteins were evaluated after treatment with BMP2. Differential gene expression and reference transcription analysis were performed.

RESULTS

Successful infection with recombinant lentivirus expressing mutIDH1 was demonstrated. The IDH1 mutation promoted glioma cell migration and invasion while positively regulating the expression of vascularization-related factors and BMP2-related receptors. BMP2 exhibited a positive regulatory effect on the migration, invasion, and angiogenesis of mutIDH1-glioma cells, possibly mediated by BMP2-induced alterations in Smad signaling pathway-related factors.After BMP2 treatment, the differential genes of MutIDH1-glioma cells are closely related to the regulation of cell migration and cell adhesion, especially the regulation of Smad-related proteins. KEGG analysis confirmed that it was related to BMP signaling pathway and TGF-β signaling pathway and cell adhesion. Enrichment analysis of gene ontology and genome encyclopedia further confirmed the correlation of these pathways.

CONCLUSION

Mutation of isocitrate dehydrogenase 1 promotes the migration, invasion, and angiogenesis of glioma cells, through its effects on the BMP2-driven Smad signaling pathway. In addition, BMP2 altered the transcriptional patterns of mutIDH1 glioma cells, enriching different gene loci in pathways associated with invasion, migration, and angiogenesis.

Lysosomes in Cancer-At the Crossroad of Good and Evil

Although it has been known for decades that lysosomes are central for degradation and recycling in the cell, their pivotal role as nutrient sensing signaling hubs has recently become of central interest. Since lysosomes are highly dynamic and in constant change regarding content and intracellular position, fusion/fission events allow communication between organelles in the cell, as well as cell-to-cell communication via exocytosis of lysosomal content and release of extracellular vesicles. Lysosomes also mediate different forms of regulated cell death by permeabilization of the lysosomal membrane and release of their content to the cytosol. In cancer cells, lysosomal biogenesis and autophagy are increased to support the increased metabolism and allow growth even under nutrient- and oxygen-poor conditions. Tumor cells also induce exocytosis of lysosomal content to the extracellular space to promote invasion and metastasis. However, due to the enhanced lysosomal function, cancer cells are often more susceptible to lysosomal membrane permeabilization, providing an alternative strategy to induce cell death. This review summarizes the current knowledge of cancer-associated alterations in lysosomal structure and function and illustrates how lysosomal exocytosis and release of extracellular vesicles affect disease progression. We focus on functional differences depending on lysosomal localization and the regulation of intracellular transport, and lastly provide insight how new therapeutic strategies can exploit the power of the lysosome and improve cancer treatment.

CLEC19A overexpression inhibits tumor cell proliferation/migration and promotes apoptosis concomitant suppression of PI3K/AKT/NF-κB signaling pathway in glioblastoma multiforme

BACKGROUND

GBM is the most frequent malignant primary brain tumor in humans. The CLEC19A is a member of the C-type lectin family, which has a high expression in brain tissue. Herein, we sought to carry out an in-depth analysis to pinpoint the role of CLEC19A expression in GBM.

METHODS

To determine the localization of CLEC19A, this protein was detected using Western blot, Immunocytochemistry/Immunofluorescence, and confocal microscopy imaging. CLEC19A expression in glioma cells and tissues was evaluated by qRT-PCR. Cell viability, proliferation, migration, and apoptosis were examined through MTT assay, CFSE assay, colony formation, wound healing assay, transwell test, and flow cytometry respectively after CLEC19A overexpression. The effect of CLEC19A overexpression on the PI3K/AKT/NF-κB signaling pathway was investigated using Western blot. An in vivo experiment substantiated the in vitro results using the glioblastoma rat models.

RESULTS

Our in-silico analysis using TCGA data and measuring CLEC19A expression level by qRT-PCR determined significantly lower expression of CLEC19A in human glioma tissues compared to healthy brain tissues. By employment of ICC/IF, confocal microscopy imaging, and Western blot we could show that CLEC19A is plausibly a secreted protein. Results obtained from several in vitro readouts showed that CLEC19A overexpression in U87 and C6 glioma cell lines is associated with the inhibition of cell proliferation, viability, and migration. Further, qRT-PCR and Western blot analysis showed CLEC19A overexpression could reduce the expression levels of PI3K, VEGFα, MMP2, and NF-κB and increase PTEN, TIMP3, RECK, and PDCD4 expression levels in glioma cell lines. Furthermore, flow cytometry results revealed that CLEC19A overexpression was associated with significant cell cycle arrest and promotion of apoptosis in glioma cell lines. Interestingly, using a glioma rat model we could substantiate that CLEC19A overexpression suppresses glioma tumor growth.

CONCLUSIONS

To our knowledge, this is the first report providing in-silico, molecular, cellular, and in vivo evidences on the role of CLEC19A as a putative tumor suppressor gene in GBM. These results enhance our understanding of the role of CLEC19A in glioma and warrant further exploration of CLEC19A as a potential therapeutic target for GBM.

Inhibition of TGF-β1-induced epithelial-mesenchymal transition in gliomas by DMC-HA

DMC-HA, a novel HDAC inhibitor, has previously demonstrated antiproliferative activity against various cancers, including gliomas. However, the role of DMC-HA in the regulation of EMT and its underlying mechanisms remain unknown. This study aimed to explore the effects of DMC-HA on TGF-β1-induced EMT in human gliomas and the underlying mechanisms involved. Our results showed that TGF-β1 induced EMT of U87 and U251 cells, leading to a decrease in epithelial marker ZO-1 and an increase in mesenchymal markers N-cadherin and Vimentin. Moreover, TGF-β1 treatment resulted in a significant increase in the migratory and invasive abilities of the cells. However, treatment with DMC-HA effectively inhibited the augmented migration and invasion of glioma cells induced by TGF-β1. Additionally, DMC-HA inhibits TGF-β1-induced EMT by suppressing canonical Smad pathway and non-canonical TGF-β/Akt and Erk signalling pathways. These findings suggest that DMC-HA has potential therapeutic implications for gliomas by inhibiting EMT progression.

KMT2D suppresses Sonic hedgehog-driven medulloblastoma progression and metastasis

The major cause of treatment failure and mortality among medulloblastoma patients is metastasis intracranially or along the spinal cord. The molecular mechanisms driving tumor metastasis in Sonic hedgehog-driven medulloblastoma (SHH-MB) patients, however, remain largely unknown. In this study we define a tumor suppressive role of KMT2D (MLL2), a gene frequently mutated in the most metastatic β-subtype. Strikingly, genetic mouse models of SHH-MB demonstrate that heterozygous loss of Kmt2d in conjunction with activation of the SHH pathway causes highly penetrant disease with decreased survival, increased hindbrain invasion and spinal cord metastasis. Loss of Kmt2d attenuates neural differentiation and shifts the transcriptional/chromatin landscape of primary and metastatic tumors toward a decrease in differentiation genes and tumor suppressors and an increase in genes/pathways implicated in advanced stage cancer and metastasis (TGFβ, Notch, Atoh1, Sox2, and Myc). Thus, secondary heterozygous KMT2D mutations likely have prognostic value for identifying SHH-MB patients prone to develop metastasis.

The role of lysosomal peptidases in glioma immune escape: underlying mechanisms and therapeutic strategies

Glioblastoma is the most common primary malignant tumor of the central nervous system, which has the characteristics of strong invasion, frequent recurrence, and rapid progression. These characteristics are inseparable from the evasion of glioma cells from immune killing, which makes immune escape a great obstacle to the treatment of glioma, and studies have confirmed that glioma patients with immune escape tend to have poor prognosis. The lysosomal peptidase lysosome family plays an important role in the immune escape process of glioma, which mainly includes aspartic acid cathepsin, serine cathepsin, asparagine endopeptidases, and cysteine cathepsins. Among them, the cysteine cathepsin family plays a prominent role in the immune escape of glioma. Numerous studies have confirmed that glioma immune escape mediated by lysosomal peptidases has something to do with autophagy, cell signaling pathways, immune cells, cytokines, and other mechanisms, especially lysosome organization. The relationship between protease and autophagy is more complicated, and the current research is neither complete nor in-depth. Therefore, this article reviews how lysosomal peptidases mediate the immune escape of glioma through the above mechanisms and explores the possibility of lysosomal peptidases as a target of glioma immunotherapy.

Germline modifiers of the tumor immune microenvironment implicate drivers of cancer risk and immunotherapy response

With the continued promise of immunotherapy for treating cancer, understanding how host genetics contributes to the tumor immune microenvironment (TIME) is essential to tailoring cancer screening and treatment strategies. Here, we study 1084 eQTLs affecting the TIME found through analysis of The Cancer Genome Atlas and literature curation. These TIME eQTLs are enriched in areas of active transcription, and associate with gene expression in specific immune cell subsets, such as macrophages and dendritic cells. Polygenic score models built with TIME eQTLs reproducibly stratify cancer risk, survival and immune checkpoint blockade (ICB) response across independent cohorts. To assess whether an eQTL-informed approach could reveal potential cancer immunotherapy targets, we inhibit CTSS, a gene implicated by cancer risk and ICB response-associated polygenic models; CTSS inhibition results in slowed tumor growth and extended survival in vivo. These results validate the potential of integrating germline variation and TIME characteristics for uncovering potential targets for immunotherapy.

Cleavage of Occludin by Cigarette Smoke-Elicited Cathepsin S Increases Permeability of Lung Epithelial Cells

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an irreversible disease mainly caused by smoking. COPD is characterized by emphysema and chronic bronchitis associated with enhanced epithelial permeability.

HYPOTHESIS

Lung biopsies from smokers revealed a decreased expression level of occludin, which is a protein involved in the cohesion of epithelial tight junctions. Moreover, the occludin level correlated negatively with smoking history (pack-years), COPD grades, and cathepsin S (CatS) activity. Thus, we examined whether CatS could participate in the modulation of the integrity of human lung epithelial barriers.

METHODS AND RESULTS

Cigarette smoke extract (CSE) triggered the upregulation of CatS by THP-1 macrophages through the mTOR/TFEB signaling pathway. In a co-culture model, following the exposure of macrophages to CSE, an enhanced level of permeability of lung epithelial (16HBE and NHBE) cells towards FITC-Dextran was observed, which was associated with a decrease in occludin level. Similar results were obtained using 16HBE and NHBE cells cultured at the air-liquid interface. The treatment of THP-1 macrophages by CatS siRNAs or by a pharmacological inhibitor restored the barrier function of epithelial cells, suggesting that cigarette smoke-elicited CatS induced an alteration of epithelial integrity via the proteolytic injury of occludin.

CONCLUSIONS

Alongside its noteworthy resistance to oxidative stress induced by cigarette smoke oxidants and its deleterious elastin-degrading potency, CatS may also have a detrimental effect on the barrier function of epithelial cells through the cleavage of occludin. The obtained data emphasize the emerging role of CatS in smoking-related lung diseases and strengthen the relevance of targeting CatS in the treatment of emphysema and COPD.

Targeting TGF-β signal transduction for fibrosis and cancer therapy

Transforming growth factor β (TGF-β) has long been identified with its intensive involvement in early embryonic development and organogenesis, immune supervision, tissue repair, and adult homeostasis. The role of TGF-β in fibrosis and cancer is complex and sometimes even contradictory, exhibiting either inhibitory or promoting effects depending on the stage of the disease. Under pathological conditions, overexpressed TGF-β causes epithelial-mesenchymal transition (EMT), extracellular matrix (ECM) deposition, cancer-associated fibroblast (CAF) formation, which leads to fibrotic disease, and cancer. Given the critical role of TGF-β and its downstream molecules in the progression of fibrosis and cancers, therapeutics targeting TGF-β signaling appears to be a promising strategy. However, due to potential systemic cytotoxicity, the development of TGF-β therapeutics has lagged. In this review, we summarized the biological process of TGF-β, with its dual role in fibrosis and tumorigenesis, and the clinical application of TGF-β-targeting therapies.

MEOX2-mediated regulation of Cathepsin S promotes cell proliferation and motility in glioma

Nuclear transcription factor Mesenchyme Homeobox 2 (MEOX2) is a homeobox gene that is originally discovered to suppress the growth of vascular smooth muscle and endothelial cells. However, whether or not it is connected to cancer is yet unknown. Here, we report that MEOX2 functions as a tumor-initiating element in glioma. Bioinformatic analyses of public databases and investigation of MEOX2 expression in patients with glioma demonstrated that MEOX2 was abundant at both mRNA and protein levels in glioma. MEOX2 expression was shown to be inversely linked with the prognosis of glioma patients. MEOX2 inhibition changed the morphology of glioma cells, inhibited cell proliferation and motility, whereas had no effect on cell apoptosis. Besides, silencing MEOX2 also hampered the epithelial-mesenchymal transition (EMT), focal adhesion formation, and F-actin assembly. Overexpression of MEOX2 exhibited opposite effects. Importantly, RNA-sequencing, ChIP-qPCR assay, and luciferase reporter assay revealed Cathepsin S (CTSS) as a novel transcriptional target of MEOX2 in glioma cells. Consistently, MEOX2 causes glioma tumor development in mice and greatly lowers the survival period of tumor-bearing mice. Our findings indicate that MEOX2 promotes tumorigenesis and progression of glioma partially through the regulation of CTSS. Targeting MEOX2-CTSS axis might be a promising alternative for the treatment of glioma.

Self-Assembly of Naturally Small Molecules into Supramolecular Fibrillar Networks for Wound Healing

Self-assemblies of bioactively natural compounds into supramolecular hydrogels without structural modifications are of interest to improve their sustained releases and bioavailabilities in vivo. However, it is still a formidable challenge to dig out such a naturally small molecule with a meticulous structure which can be self-assembled to form a hydrogel for biomedical applications. Here, a new hydrogel consisting only of gallic acid (GA) via π-π stacking and hydrogen bond interactions, whereas none of GA analogues can form the similar supramolecular hydrogels, is reported. This interesting phenomenon is intriguing to further investigate the potential applications of GA hydrogels in wound healing. Notably, this GA hydrogel has rod-like structures with lengths varying from 10 to 100 µm. The biocompatibility and antibacterial tests prove that this well-assembled GA hydrogel has no cytotoxicity and excellent antibacterial activities against Escherichia coli and Staphylococcus aureus. Moreover, the GA hydrogel can significantly accelerate the process of wound healing with or without bacterial infections by mediation of inflammation signaling pathways. It is believed that the current study may shed a new light on the design of a supramolecular hydrogel based on self-assemblies of naturally small molecules to improve their bioavailabilities and diversify their uses in biomedical applications.

Knockdown of CD44 inhibits proliferation, migration and invasion of osteosarcoma cells accompanied by downregulation of cathepsin S

BACKGROUND

Osteosarcoma (OS) is a malignant bone tumour of mesenchymal origin. These tumours are characterised by rich vascularisation, therefore promoting rapid proliferation and facilitating metastasis. CD44 has been reported to be involved in OS, but its role and molecular mechanisms in the pathogenesis of the disease are not fully determined.

METHODS

In this study, we investigated the antitumor effect of CD44 on the development of OS and further explored the molecular mechanisms. The expression of CD44, cathepsin S and MMP-9 was detected by Western blot (WB) and reverse transcription-polymerase chain reaction (RT-qPCR) in different cell lines (MG63, U2OS OS and hFOB 1.19). To elucidate the role of CD44 in OS, MG63 and U2OS cells were treated with small interference RNA (siRNA) to knock down CD44, and the knockdown efficiency was validated with GFP and RT-qPCR. Furthermore, cell proliferation was assayed using Cell Counting Kit‑8 (CCK-8) and colony formation assays, and cell migration and invasion were assayed by transwell and wound-healing assays.

RESULTS

We found that CD44 expression in the MG63 and U2OS OS cell lines was markedly increased compared to that of the human osteoblast hFOB 1.19 cell line. Knockdown of CD44 inhibited proliferation, migration and invasion of MG63 and U2OS cells. Cathepsin S expression in the MG63 and U2OS OS cell lines was increased compared to that of the human osteoblast hFOB 1.19 cell line. When CD44 was knocked down, its expression level went down.

CONCLUSION

Taken together, our data reinforced the evidence that CD44 knockdown inhibited cell proliferation, migration and invasion of OS cells accompanied by altered expression of cathepsin S. These findings offer new clues for OS development and progression, suggesting CD44 as a potential therapeutic target for OS.

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.

TRAM2 promotes the malignant progression of glioma through PI3K/AKT/mTOR pathway

Molecular biomarkers play an important guidance role in the diagnosis and treatment of glioma. It has been found that TRAM2 (translocation associated membrane protein 2) drives human cancers development. Here we report that TRAM2 activity is required for malignancy properties of glioma. In this study, we demonstrated that TRAM2 is over-expressed in glioma and cell lines, particularly in the mesenchymal subtype, and glioma patients with high expression of TRAM2 is associated with poorer survival. Silencing of TRAM2 significantly suppresses glioma cell proliferation, invasion, migration and EMT in vitro, and inhibits tumorigenicity of glioma cell in vivo. We further identify that TRAM2 is positively associated with activation of the PI3K/AKT/mTOR signaling in glioma. 740Y-P, a PI3K activator, reversed the effects of TRAM2 silencing on glioma cell proliferation, invasion, migration and EMT process. Taken together, these findings establish that TRAM2/PI3K/AKT/mTOR signaling drives malignancy properties of glioma and indicate that TRAM2 may act as a potential therapeutic target for glioma.