Calpain-6 controls the fate of sarcoma stem cells by promoting autophagy and preventing senescence

Targeting KIFC1 Promotes Senescence in Soft Tissue Sarcoma via FXR1-Dependent Regulation of MAD2L1 mRNA Stability

Patients diagnosed with soft tissue sarcoma (STS) often present at intermediate to advanced stages, with inherently limited therapeutic options available. There is an urgent need to identify novel therapeutic targets. In this study, by screening STS data from the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression (GTEx) databases, KIFC1 is identified as a potential biomarker and a promising therapeutic target for STS. Notably, a significant increase in KIFC1 levels, which exhibited a strong correlation with a poor prognosis in STS patients is observed. The findings revealed that knockout of KIFC1 suppressed STS growth both in vitro and in vivo. Furthermore, KIFC1 is found to regulate cellular senescence in STS, which has not been reported before. that targeting KIFC1 induced cellular senescence via interacting with FXR1, an RNA-binding protein is discovered, thereby further stabilizing MAD2L1 mRNA in an m6A-dependent manner. Additionally, the suppression of KIFC1 markedly diminished the growth of patient-derived xenografts (PDX) and triggered senescence. This study provides the first evidence that KIFC1 inhibition induces cellular senescence through MAD2L1, underscoring KIFC1 as a novel prognostic biomarker and a potential therapeutic target for STS.

Calpain and Cardiometabolic Diseases

Calpain is defined as a member of the superfamily of cysteine proteases possessing the CysPC motif within the gene. Calpain-1 and -2, which are categorized as conventional isozymes, execute limited proteolysis in a calcium-dependent fashion. Accordingly, the calpain system participates in physiological and pathological phenomena, including cell migration, apoptosis, and synaptic plasticity. Recent investigations have unveiled the contributions of both conventional and unconventional calpains to the pathogenesis of cardiometabolic disorders. In the context of atherosclerosis, overactivation of conventional calpain attenuates the barrier function of vascular endothelial cells and decreases the immunosuppressive effects attributed to lymphatic endothelial cells. In addition, calpain-6 induces aberrant mRNA splicing in macrophages, conferring atheroprone properties. In terms of diabetes, polymorphisms of the calpain-10 gene can modify insulin secretion and glucose disposal. Moreover, conventional calpain reportedly participates in amino acid production from vascular endothelial cells to induce alteration of amino acid composition in the liver microenvironment, thereby facilitating steatohepatitis. Such multifaceted functionality of calpain underscores its potential as a promising candidate for pharmaceutical targets for the treatment of cardiometabolic diseases. Consequently, the present review highlights the pivotal role of calpains in the complications of cardiometabolic diseases and embarks upon a characterization of calpains as molecular targets.

Doxorubicin-induced senescence promotes resistance to cell death by modulating genes associated with apoptotic and necrotic pathways in prostate cancer DU145 CD133+/CD44+ cells

Cancer stem cells (CSCs) are the most important cause of cancer treatment failure. Traditional cancer treatments, such as chemotherapy and radiotherapy, damage healthy cells alongside malignant cells, leading to severe adverse effects. Therefore, inducing cellular senescence without triggering apoptosis, which further damages healthy cells, may be an alternative strategy. However, there is insufficient knowledge regarding senescence induction in CSCs that show resistance to treatment and stemness properties. The present study aims to elucidate the effects of senescence induction on proliferation, cell cycle, and apoptosis in prostate CSCs and non-CSCs. Prostate CSCs were isolated from DU145 cancer cells using the FACS method. Subsequently, senescence induction was performed in RWPE-1, DU145, prostate CSCs, and non-CSCs by using different concentrations of Doxorubicin (DOX). Cellular senescence was detected using the senescence markers SA-β-gal, Ki67, and senescence-associated heterochromatin foci (SAHF). The effects of senescence on cell cycle and apoptosis were evaluated using the Muse Cell Analyzer, and genes in signaling pathways associated with the apoptotic/necrotic pathway were analyzed by real-time PCR. Prostate CSCs were isolated with 95.6 ± 1.4% purity according to CD133+/CD44+ characteristics, and spheroid formation belonging to stem cells was observed. After DOX-induced senescence, we observed morphological changes, SA-β-gal positivity, SAHF, and the lack of Ki67 in senescent cells. Furthermore; we detected G2/M cell cycle arrest and downregulation of various apoptosis-related genes in senescent prostate CSCs. Our results showed that DOX is a potent inducer of senescence for prostate CSCs, inhibits proliferation by arresting the cell cycle, and senescent prostate CSCs develop resistance to apoptosis.

Autophagy Modulation as a Potential Therapeutic Strategy in Osteosarcoma: Current Insights and Future Perspectives

Autophagy, the process that enables the recycling and degradation of cellular components, is essential for homeostasis, which occurs in response to various types of stress. Autophagy plays an important role in the genesis and evolution of osteosarcoma (OS). The conventional treatment of OS has limitations and is not always effective at controlling the disease. Therefore, numerous researchers have analyzed how controlling autophagy could be used as a treatment or strategy to reverse resistance to therapy in OS. They highlight how the inhibition of autophagy improves the efficacy of chemotherapeutic treatments and how the promotion of autophagy could prove positive in OS therapy. The modulation of autophagy can also be directed against OS stem cells, improving treatment efficacy and preventing cancer recurrence. Despite promising findings, future studies are needed to elucidate the molecular mechanisms of autophagy and its relationship to OS, as well as the mechanisms underlying the functioning of autophagic modulators. Careful evaluation is required as autophagy modulation may have adverse effects on normal cells, and the optimization of autophagic modulators for use as drugs in OS is imperative.

Novel insights into the progression and prognosis of the calpain family members in hepatocellular carcinoma: a comprehensive integrated analysis

Objectives: The goal of our bioinformatics study was to comprehensively analyze the association between the whole calpain family members and the progression and prognosis of hepatocellular carcinoma (HCC). Methods: The data were collected from The Cancer Genome Atlas (TCGA). The landscape of the gene expression, copy number variation (CNV), mutation, and DNA methylation of calpain members were analyzed. Clustering analysis was performed to stratify the calpain-related groups. The least absolute shrinkage and selection operator (LASSO)-based Cox model was used to select hub survival genes. Results: We found 14 out of 16 calpain members expressed differently between tumor and normal tissues of HCC. The clustering analyses revealed high- and low-risk calpain groups which had prognostic difference. We found the high-risk calpain group had higher B cell infiltration and higher expression of immune checkpoint genes HAVCR2, PDCD1, and TIGHT. The CMap analysis found that the histone deacetylase (HDAC) inhibitor trichostatin A and the PI3K-AKT-mTOR pathway inhibitors LY-294002 and wortmannin might have a therapeutic effect on the high-risk calpain group. The DEGs between calpain groups were identified. Subsequent univariate Cox analysis of each DEG and LASSO-based Cox model obtained a calpain-related prognostic signature. The risk score model of this signature showed good ability to predict the overall survival of HCC patients in TCGA datasets and external validation datasets from the Gene Expression Omnibus database and the International Cancer Genome Consortium database. Conclusion: We found that calpain family members were associated with the progression, prognosis, and drug response of HCC. Our results require further studies to confirm.

H3K4me3 mediates uterine leiomyoma pathogenesis via neuronal processes, synapsis components, proliferation, and Wnt/β-catenin and TGF-β pathways

BACKGROUND

Uterine leiomyomas (UL) are the most common benign tumor in women of reproductive age. Their pathology remains unclear, which hampers the development of safe and effective treatments. Raising evidence suggests epigenetics as a main mechanism involved in tumor development. Histone modification is a key component in the epigenetic regulation of gene expression. Specifically, the histone mark H3K4me3, which promotes gene expression, is altered in many tumors. In this study, we aimed to identify if the histone modification H3K4me3 regulates the expression of genes involved in uterine leiomyoma pathogenesis.

METHODS

Prospective study integrating RNA-seq (n = 48) and H3K4me3 CHIP-seq (n = 19) data of uterine leiomyomas versus their adjacent myometrium. Differentially expressed genes (FDR < 0.01, log2FC > 1 or < - 1) were selected following DESeq2, edgeR, and limma analysis. Their differential methylation and functional enrichment (FDR < 0.05) were respectively analyzed with limma and ShinyGO.

RESULTS

CHIP-seq data showed a global suppression of H3K4me3 in uterine leiomyomas versus their adjacent myometrial tissue (p-value< 2.2e-16). Integrating CHIP-seq and RNA-seq data highlighted that transcription of 696/922 uterine leiomyoma-related differentially expressed genes (DEG) (FDR < 0.01, log2FC > 1 or < - 1) was epigenetically mediated by H3K4me3. Further, 50 genes were differentially trimethylated (FDR < 0.05), including 33 hypertrimethylated/upregulated, and 17 hypotrimethylated/downregulated genes. Functional enrichment analysis of the latter showed dysregulation of neuron-related processes and synapsis-related cellular components in uterine leiomyomas, and a literature review study of these DEG found additional implications with tumorigenesis (i.e. aberrant proliferation, invasion, and dysregulation of Wnt/β-catenin, and TGF-β pathways). Finally, SATB2, DCX, SHOX2, ST8SIA2, CAPN6, and NPTX2 proto-oncogenes were identified among the hypertrimethylated/upregulated DEG, while KRT19, ABCA8, and HOXB4 tumor suppressor genes were identified among hypotrimethylated/downregulated DEG.

CONCLUSIONS

H3K4me3 instabilities alter the expression of oncogenes and tumor suppressor genes, inducing aberrant proliferation, and dysregulated Wnt/β-catenin, and TGF-β pathways, that ultimately promote uterine leiomyoma progression. The reversal of these histone modifications may be a promising new therapeutic alternative for uterine leiomyoma patients.

A calpain-6/YAP axis in sarcoma stem cells that drives the outgrowth of tumors and metastases

Sarcomas include cancer stem cells, but how these cells contribute to local and metastatic relapse is largely unknown. We previously showed the pro-tumor functions of calpain-6 in sarcoma stem cells. Here, we use an osteosarcoma cell model, osteosarcoma tissues and transcriptomic data from human tumors to study gene patterns associated with calpain-6 expression or suppression. Calpain-6 modulates the expression of Hippo pathway genes and stabilizes the hippo effector YAP. It also modulates the vesicular trafficking of β-catenin degradation complexes. Calpain-6 expression is associated with genes of the G2M phase of the cell cycle, supports G2M-related YAP activities and up-regulated genes controlling mitosis in sarcoma stem cells and tissues. In mouse models of bone sarcoma, most tumor cells expressed calpain-6 during the early steps of tumor out-growth. YAP inhibition prevented the neoformation of primary tumors and metastases but had no effect on already developed tumors. It could even accelerate lung metastasis associated with large bone tumors by affecting tumor-associated inflammation in the host tissues. Our results highlight a specific mechanism involving YAP transcriptional activity in cancer stem cells that is crucial during the early steps of tumor and metastasis outgrowth and that could be targeted to prevent sarcoma relapse.

Blood compatibility of widely used central venous catheters; an experimental study

An inserted central venous catheter (CVC) is considered foreign material by the inert host defence systems and induce inflammation and thrombus formation. The objective of this study was to evaluate blood compatibility of six commonly used CVCs. Three coated and three uncoated CVC materials were tested in a modified Chandler loop model. Each catheter material circulated in blood from ten different healthy volunteers for 1 h. Blood cell counts and measurements of the inert host defence systems were performed on blood samples from the loop. All the tested catheters demonstrated impact on blood cells, contact coagulation, the complement system, or inflammatory markers, although the impact varied significantly. Of the catheters we evaluated, the most unfavourable blood compatibility profile was found for the polyurethane CVC coated with chlorohexidine and silver sulfadiazine. The greatest variation in blood compatibility between test runs was noted for the silicone dialysis catheter. Poor blood compatibility should be taken seriously but given the experimental design of the current study the clinical significance remains to be evaluated.

Metastatic Progression of Osteosarcomas: A Review of Current Knowledge of Environmental versus Oncogenic Drivers

Simple Summary

Osteosarcomas are heterogeneous bone tumors with complex genetic and chromosomic alterations. The numerous patients with metastatic osteosarcoma have a very poor prognosis, and only those who can have full surgical resection of the primary tumor and of all the macro metastasis can survive. Despite the recent improvements in prediction and early detection of metastasis, big efforts are still required to understand the specific mechanisms of osteosarcoma metastatic progression, in order to reveal novel therapeutic targets.

Abstract

Metastases of osteosarcomas are heterogeneous. They may grow simultaneously with the primary tumor, during treatment or shortly after, or a long time after the end of the treatment. They occur mainly in lungs but also in bone and various soft tissues. They can have the same histology as the primary tumor or show a shift towards a different differentiation path. However, the metastatic capacities of osteosarcoma cells can be predicted by gene and microRNA signatures. Despite the identification of numerous metastasis-promoting/predicting factors, there is no efficient therapeutic strategy to reduce the number of patients developing a metastatic disease or to cure these metastatic patients, except surgery. Indeed, these patients are generally resistant to the classical chemo- and to immuno-therapy. Hence, the knowledge of specific mechanisms should be extended to reveal novel therapeutic approaches. Recent studies that used DNA and RNA sequencing technologies highlighted complex relations between primary and secondary tumors. The reported results also supported a hierarchical organization of the tumor cell clones, suggesting that cancer stem cells are involved. Because of their chemoresistance, their plasticity, and their ability to modulate the immune environment, the osteosarcoma stem cells could be important players in the metastatic process.

Recent progress of autophagy signaling in tumor microenvironment and its targeting for possible cancer therapeutics

Autophagy, a lysosomal catabolic process, involves degradation of cellular materials, protein aggregate, and dysfunctional organelles to maintain cellular homeostasis. Strikingly, autophagy exhibits a dual-sided role in cancer; on the one hand, it promotes clearance of transformed cells and inhibits tumorigenesis, while cytoprotective autophagy has a role in sustaining cancer. The autophagy signaling in the tumor microenvironment (TME) during cancer growth and therapy is not adequately understood. The review highlights the role of autophagy signaling pathways to support cancer growth and progression in adaptation to the oxidative and hypoxic context of TME. Furthermore, autophagy contributes to regulating the metabolic switch for generating sufficient levels of high-energy metabolites, including amino acids, ketones, glutamine, and free fatty acids for cancer cell survival. Interestingly, autophagy has a critical role in modulating the tumor-associated fibroblast resulting in different cytokines and paracrine signaling mediated angiogenesis and invasion of pre-metastatic niches to secondary tumor sites. Moreover, autophagy promotes immune evasion to inhibit antitumor immunity, and autophagy inhibitors enhance response to immunotherapy with infiltration of immune cells to the TME niche. Furthermore, autophagy in TME maintains and supports the survival of cancer stem cells resulting in chemoresistance and therapy recurrence. Presently, drug repurposing has enabled the use of lysosomal inhibitor-based antimalarial drugs like chloroquine and hydroxychloroquine as clinically available autophagy inhibitors in cancer therapy. We focus on the recent developments of multiple autophagy modulators from pre-clinical trials and the challenges in developing autophagy-based cancer therapy.

Mechanisms of cancer stem cell senescence: Current understanding and future perspectives

Cancer stem cells (CSCs) are a small population of heterogeneous tumor cells with the capacity of self-renewal and aberrant differentiation for immortality and divergent lineages of cancer cells. In contrast to bulky tumor cells, CSCs remain less differentiated and resistant to therapy even when targeted with tissue-specific antigenic markers. This makes CSCs responsible for not only tumor initiation, development, but also tumor recurrence. Emerging evidence suggests that CSCs can undergo cell senescence, a non-proliferative state of cells in response to stress. While cell senescence attenuates tumor cell proliferation, it is commonly regarded as a tumor suppressive mechanism. However, mounting research indicates that CSC senescence also provides these cells with the capacity to evade cytotoxic effects from cancer therapy, exacerbating cancer relapse and metastasis. Recent studies demonstrate that senescence drives reprogramming of cancer cell toward stemness and promotes CSC generation. In this review, we highlight the origin, heterogeneity and senescence regulatory mechanisms of CSCs, the complex relationship between CSC senescence and tumor therapy, and the recent beneficial effects of senotherapy on eliminating senescent tumor cells.

Calpain 6 inhibits autophagy in inflammatory environments: A preliminary study on myoblasts and a chronic kidney disease rat model

A non-classical calpain, calpain 6 (CAPN6), can inhibit skeletal muscle differentiation and regeneration. In the present study, the role of CAPN6 in the regulation of the autophagy of myoblasts in vitro was investigated. The underlying molecular events and the CAPN6 level in atrophic skeletal muscle in a rat model of chronic kidney disease (CKD) were also investigated. In vitro, CAPN6 was overexpressed, or knocked down, in rat L6 myoblasts to assess autophagy and related gene expression and co-localization. Subsequently, myoblasts were treated with a mixture of cytokines, and relative gene expression and autophagy were assessed. A rat model of CKD for muscle atrophy was established, and blood chemical level and the expression of CAPN6 in muscle were assessed. The data revealed that the knockdown of CAPN6 in rat myoblasts resulted in increased microtubule-associated protein 1 light chain 3 (LC3) levels, while its overexpression decreased LC3 levels and impaired autophagy. Additionally, it was observed that the co-localization of mammalian target of rapamycin (mTOR) and lysosomal-associated membrane protein 1 (LAMP1), a lysosomal marker, proteins was increased. In addition, mTOR, Raptor and α-tubulin (a marker of microtubules) increased in the CAPN6 overexpression group. However, inflammatory cytokines, such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (INF)-γ and lipopolysaccharides upregulated CAPN6 expression, inhibited L6 myoblast autophagy and stabilized mTOR activity. Furthermore, the animal model successfully mimicked human disease as regards an increase in body weight, and a reduction in muscle mass, cross-sectional area and blood biomarker concentrations; a slight increase in CAPN6 mRNA and protein levels in muscles was observed. Finally, the data of the present study suggested that CAPN6 reduced autophagy via the maintenance of mTOR signaling, which may play a role in CKD-related muscle atrophy. However, future studies are required to determine whether CAPN6 may be used as an intervention target for CKD-related skeletal muscle atrophy.

Gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas

BACKGROUND

Breast carcinoma is one of the most common tumors in women. The immune microenvironment, especially T cell infiltration, is related to the occurrence and prognosis of breast carcinoma.

OBJECTIVE

This study investigated the gene expression patterns associated with tumor-infiltrating CD4+ and CD8+ T cells in invasive breast carcinomas.

METHODS

The gene expression data and corresponding clinical phenotype data from the Cancer Genome Atlas Breast Invasive Carcinoma (TCGA-BRCA) were downloaded. The stromal and immune score were calculated using ESTIMATE. The differentially expressed genes (DEGs) with a high vs. low stromal score and a high vs. low immune score were screened and then functionally enriched. The tumor-infiltrating immune cells were investigated using the Cibersort algorithm, and the CD4+ and CD8+ T cell-related genes were identified using a Spearman correlation test of infiltrating abundance with the DEGs. Moreover, the miRNA-mRNA pairs and lncRNA-miRNA pairs were predicted to construct the competing endogenous RNAs (ceRNA) network. Kaplan-Meier (K-M) survival curves were also plotted.

RESULTS

In total, 478 DEGs with a high vs. low stromal score and 796 DEGs with a high vs. low immune score were identified. In addition, 39 CD4+ T cell-related genes and 78 CD8+ T cell-related genes were identified; of these, 14 genes were significantly associated with the prognosis of BRCA patients. Moreover, for CD4+ T cell-related genes, the chr22-38_28785274-29006793.1-miR-34a/c-5p-CAPN6 axis was identified from the ceRNA network, whereas the chr22-38_28785274-29006793.1-miR-494-3p-SLC9A7 axis was identified for CD8+ T cell-related genes.

CONCLUSIONS

The chr22-38_28785274-29006793.1-miR-34a/c-5p-CAPN6 axis and the chr22-38_28785274-29006793.1-miR-494-3p-SLC9A7 axis might regulate cellular activities associated with CD4+ and CD8+ T cell infiltration, respectively, in BRCA.

CAPN6 in disease: An emerging therapeutic target (Review)

As a member of the calpain protein family, calpain6 (CAPN6) is highly expressed mainly in the placenta and embryos. It plays a number of important roles in cellular processes, such as the stabilization of microtubules, the main-tenance of cell stability, the control of cell movement and the inhibition of apoptosis. In recent years, various studies have found that CAPN6 is one of the contributing factors associated with the tumorigenesis of uterine tumors and osteosarcoma, and that CAPN6 participates in the development of tumors by promoting cell proliferation and angiogenesis, and by inhibiting apoptosis, which is mainly regulated by the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathway. Due to its abnormal cellular expression, CAPN6 has also been found to be associated with a number of diseases, such as white matter damage and muscular dystrophy. Therefore, CAPN6 may be a novel therapeutic target for these diseases. In the present review, the role of CAPN6 in disease and its possible use as a target in various therapies are discussed.

Macrophage migration inhibitory factor rejuvenates aged human mesenchymal stem cells and improves myocardial repair

The beneficial functions of mesenchymal stem cells (MSCs) decline with age, limiting their therapeutic efficacy for myocardial infarction (MI). Macrophage migration inhibitory factor (MIF) promotes cell proliferation and survival. We investigated whether MIF overexpression could rejuvenate aged MSCs and increase their therapeutic efficacy in MI. Young and aged MSCs were isolated from the bone marrow of young and aged donors. Young MSCs, aged MSCs, and MIF-overexpressing aged MSCs were transplanted into the peri-infarct region in a rat MI model. Aged MSCs exhibited a lower proliferative capacity, lower MIF level, greater cell size, greater senescence-associated-β-galactosidase activity, and weaker paracrine effects than young MSCs. Knocking down MIF in young MSCs induced cellular senescence, whereas overexpressing MIF in aged MSCs reduced cellular senescence. MIF rejuvenated aged MSCs by activating autophagy, an effect largely reversed by the autophagy inhibitor 3-methyladenine. MIF-overexpressing aged MSCs induced angiogenesis and prevented cardiomyocyte apoptosis to a greater extent than aged MSCs, and had improved heart function and cell survival more effectively than aged MSCs four weeks after MI. Thus, MIF rejuvenated aged MSCs by activating autophagy and enhanced their therapeutic efficacy in MI, suggesting a novel MSC-based therapeutic strategy for cardiovascular diseases in the aged population.

CAGE-miR-140-5p-Wnt1 Axis Regulates Autophagic Flux, Tumorigenic Potential of Mouse Colon Cancer Cells and Cellular Interactions Mediated by Exosomes

Although the cancer/testis antigen CAGE has been implicated in tumorigenesis, the molecular mechanisms of CAGE-promoted tumorigenesis remain largely unknown. CT26^Flag−CAGE cells, CT26 (mouse colon cancer cells) cells stably expressing CAGE, were established to investigate CAGE-promoted tumorigenesis. Down-regulation of CAGE led to decreased autophagic flux in CT26^Flag−CAGE cells. CAGE interacted with Beclin1, a mediator of autophagy. The CT26^Flag−CAGE cells showed enhanced autophagosome formation and displayed greater tumor spheroid-forming potential than CT26 cells. MicroRNA array analysis revealed that CAGE decreased the expression of various microRNAs, including miR-140-5p, in CT26 cells. CAGE was shown to bind to the promoter sequences of miR-140-5p. MiR-140-5p inhibition increased the tumorigenic potential of and autophagic flux in CT26 cells. A miR-140-5p mimic exerted negative effects on the tumorigenic potential of CT26^Flag−CAGE cells and autophagic flux in CT26^Flag−CAGE cells. MiR-140-5p was predicted to bind to the 3′-UTR of Wnt1. CT26^Flag−CAGE cells showed higher expression of Wnt1 than CT26 cells. Down-regulation of Wnt1 decreased autophagic flux. Luciferase activity assays showed the direct regulation of wnt1 by miR-140-5p. Tumor tissue derived from the CT26^Flag−CAGE cells revealed higher expressions of factors associated with activated mast cells and tumor-associated macrophages than tumor tissue derived from CT26 cells. Culture medium from the CT26^Flag−CAGE cells increased autophagic flux in CT26 cells, mast cells and macrophages. Culture medium from the CT26^Flag−CAGE cells increased CD163 and autophagic flux in CT26 cells, mast cells, and macrophages in a Wnt1-dependent manner. Exosomes from CT26^Flag−CAGE cells increased autophagc flux in CT26 cells, mast cells, and macrophages. Exosomes from CT26^Flag−CAGE cells increased the tumorigenic potential of CT26 cells. Wnt1 was shown to be present within the exosomes. Recombinant Wnt1 protein increased autophagic flux in CT26, mast cells, and macrophages. Recombinant wnt1 protein mediated interactions between the CT26 cells, mast cells, and macrophages. Our results showed novel roles for the CAGE-miR-140-5p-Wnt1 axis in autophagic flux and cellular interactions mediated by exosomes.

Non-proteolytic calpain-6 interacts with VEGFA and promotes angiogenesis by increasing VEGF secretion

Angiogenesis is involved in both normal physiological and pathological conditions. Vascular endothelial growth factor (VEGF) is a major factor for promoting angiogenesis. The current anti-VEGF therapies have limited efficacy and significant adverse effects. To find novel targets of VEGFA for angiogenesis inhibition, we performed yeast two-hybrid screening and identified calpain-6 as a novel VEGFA-interaction partner and confirmed the endogenous VEGFA–calpain-6 interaction in mammalian placenta. A domain mapping study revealed that the Gly321–Asp500 domain in calpain-6 is required for the interaction with the C-terminus of the VEGFA protein. The functional significance of the VEGFA–calpain-6 interaction was explored by assessing its effect on angiogenesis in vitro. Whereas forced overexpression of calpain-6 increased the secretion of the VEGF protein and tube formation, knockdown of calpain-6 expression abrogated the calpain-6-mediated VEGF secretion and tube formation in HUVECs. Consistent with the domain mapping result, overexpressing calpain-6 without the VEGFA-interacting domain III (Gly321–Asp500) failed to increase the secretion of VEGF protein. Our results identify calpain-6, an unconventional non-proteolytic calpain, as a novel VEGFA-interacting protein and demonstrate that their interaction is necessary to enhance VEGF secretion. Thus, calpain-6 might be a potential molecular target for angiogenesis inhibition in many diseases.

Deficiency of calpain-6 inhibits primary ciliogenesis

The primary cilium is a microtubule-based structure projecting from a cell. Although the primary cilium shows no motility, it can recognize environmental stimuli. Thus, ciliary defects cause severe abnormalities called ciliopathies. Ciliogenesis is a very complex process and involves a myriad of components and regulators. In order to excavate the novel positive regulators of ciliogenesis, we performed mRNA microarray using starved NIH/3T3 cells. We selected 62 murine genes with corresponding human orthologs, with significantly upregulated expression at 24 h after serum withdrawal. Finally, calpain-6 was selected as a positive regulator of ciliogenesis. We found that calpain-6 deficiency reduced the percentage of ciliated cells and impaired sonic hedgehog signaling. It has been speculated that this defect might be associated with decreased levels of α-tubulin acetylation at lysine 40. This is the first study to report a novel role of calpain-6 in the formation of primary cilia.

Role of autophagy in osteosarcoma

Osteosarcoma (OS) is the most common primary bone tumour in children and adolescents. It is a highly aggressive tumor with a tendency to spread to the lungs, which are the most common site of metastasis. Advanced osteosarcoma patients with metastasis share a poor prognosis. Despite the use of chemotherapy to treat OS, the 5-year overall survival rate for patients has remained unchanged at 65–70% for the past 20 years. In addition, the 5-year survival of patients with a metastatic disease is around 20%, highlighting the need for novel therapeutic targets.

Autophagy is an intracellular degradation process which eliminates and recycles damaged proteins and organelles to improve cell lifespan. In the context of cancer, numerous studies have demonstrated that autophagy is used by tumor cells to repress initial steps of carcinogenesis and/or support the survival and growth of established tumors. In osteosarcoma, autophagy appears to be deregulated and could also act both as a pro or anti-tumoral process. In this manuscript, we aim to review these major findings regarding the role of autophagy in osteosarcoma.

Killing Two Angry Birds with One Stone: Autophagy Activation by Inhibiting Calpains in Neurodegenerative Diseases and Beyond

Proteolytic machineries execute vital cellular functions and their disturbances are implicated in diverse medical conditions, including neurodegenerative diseases. Interestingly, calpains, a class of Ca²⁺-dependent regulatory proteases, can modulate the degradational system of autophagy by cleaving proteins involved in this pathway. Moreover, both machineries are common players in many molecular pathomechanisms and have been targeted individually or together, as a therapeutic strategy in experimental setups. In this review, we briefly introduce calpains and autophagy, with their roles in health and disease, and focus on their direct pathologically relevant interplay in neurodegeneration and beyond. The modulation of calpain activity may comprise a promising treatment approach to attenuate the deregulation of these two essential mechanisms.