Autophagy in Osteosarcoma Cancer Stem Cells Is Critical Process which Can Be Targeted by the Antipsychotic Drug Thioridazine

Targeting autophagy by antipsychotic phenothiazines: potential drug repurposing for cancer therapy

Cancer is recognized as the major cause of death worldwide and the most challenging public health issues. Tumor cells exhibit molecular adaptations and metabolic reprograming to sustain their high proliferative rate and autophagy plays a pivotal role to supply the high demand for metabolic substrates and for recycling cellular components, which has attracted the attention of the researchers. The modulation of the autophagic process sensitizes tumor cells to chemotherapy-induced cell death and reverts drug resistance. In this regard, many in vitro and in vivo studies having shown the anticancer activity of phenothiazine (PTZ) derivatives due to their potent cytotoxicity in tumor cells. Interestingly, PTZ have been used as antiemetics in antitumor chemotherapy-induced vomiting, maybe exerting a combined antitumor effect. Among the mechanisms of cytotoxicity, the modulation of autophagy by these drugs has been highlighted. Therefore, the use of PTZ derivatives can be considered as a repurposing strategy in antitumor chemotherapy. Here, we provided an overview of the effects of antipsychotic PTZ on autophagy in tumor cells, evidencing the molecular targets and discussing the underlying mechanisms. The modulation of autophagy by PTZ in tumor cells have been consistently related to their cytotoxic action. These effects depend on the derivative, their concentration, and also the type of cancer. Most data have shown the impairment of autophagic flux by PTZ, probably due to the blockade of lysosome-autophagosome fusion, but some studies have also suggested the induction of autophagy. These data highlight the therapeutic potential of targeting autophagy by PTZ in cancer chemotherapy.

The role of autophagy in hypoxia-induced radioresistance

Radiotherapy is a widely used treatment modality against cancer, and although survival rates are increasing, radioresistant properties of tumours remain a significant barrier for curative treatment. Tumour hypoxia is one of the main contributors to radioresistance and is common in most solid tumours. Hypoxia is responsible for many molecular changes within the cell which helps tumours to survive under such challenging conditions. These hypoxia-induced molecular changes are predominantly coordinated by the hypoxia inducible factor (HIF) and have been linked with the ability to confer resistance to radiation-induced cell death. To overcome this obstacle research has been directed towards autophagy, a cellular process involved in self degradation and recycling of macromolecules, as HIF plays a large role in its coordination under hypoxic conditions. The role that autophagy has following radiotherapy treatment is conflicted with evidence of both cytoprotective and cytotoxic effects. This literature review aims to explore the intricate relationship between radiotherapy, hypoxia, and autophagy in the context of cancer treatment. It provides valuable insights into the potential of targeting autophagy as a therapeutic strategy to improve the response of hypoxic tumours to radiotherapy.

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.

Crosstalk between autophagy and CSCs: molecular mechanisms and translational implications

Cancer stem cells(CSCs) play a key role in regulating tumorigenesis, progression, as well as recurrence, and possess typical metabolic characteristics. Autophagy is a catabolic process that can aid cells to survive under stressful conditions such as nutrient deficiency and hypoxia. Although the role of autophagy in cancer cells has been extensively studied, CSCs possess unique stemness, and their potential relationship with autophagy has not been fully analyzed. This study summarizes the possible role of autophagy in the renewal, proliferation, differentiation, survival, metastasis, invasion, and treatment resistance of CSCs. It has been found that autophagy can contribute to the maintenance of CSC stemness, facilitate the tumor cells adapt to changes in the microenvironment, and promote tumor survival, whereas in some other cases autophagy acts as an important process involved in the deprivation of CSC stemness thus leading to tumor death. Mitophagy, which has emerged as another popular research area in recent years, has a great scope when explored together with stem cells. In this study, we have aimed to elaborate on the mechanism of action of autophagy in regulating the functions of CSCs to provide deeper insights for future cancer treatment.

Thioridazine combined with carboplatin results in synergistic inhibition of triple negative breast cancer by targeting cancer stem cells

Cancer stem cells (CSCs) in triple-negative breast cancer (TNBC) are closely related to tumorigenesis and metastasis. Thioridazine (THZ) is a usual phenothiazine antipsychotic drug that can destroy CSCs. We aimed to explore whether THZ could sensitize metastatic TNBC cells, especially the CSCs, to carboplatin (CBP) treatment. Metastatic TNBC cells, 4T1 cells, and tumor-bearing mice were treated with THZ and CBP as monotherapy or combination therapy. MTT, flow cytometry, electron microscopy, immunohistochemistry and western blotting were applied to assess the cell viability, apoptosis, mitochondrial morphology and the relevant protein levels, respectively. Tumor size and lung metastasis under different treatments as well as tumorigenesis of residual tumor cells from each group were monitored. THZ combined with CBP inhibited 4T1 tumor cell proliferation and induced apoptosis by inhibiting the PI3K-AKT-mTOR pathway and activating estrogen receptor stress. THZ also showed strong activity against breast CSCs, THZ combined with CBP significantly destroyed cancer cells, inhibited lung metastasis and relieved the tumor burden; Our data demonstrated that THZ can sensitize TNBC cells to CBP treatment and this combination therapy may provide a bright strategy for TNBC treatment by targeting both cancer cells and CSCs.

Chemotherapy Resistance: Role of Mitochondrial and Autophagic Components

Simple Summary

Chemotherapy resistance is a common occurrence during cancer treatment that cancer researchers are attempting to understand and overcome. Mitochondria are a crucial intracellular signaling core that are becoming important determinants of numerous aspects of cancer genesis and progression, such as metabolic reprogramming, metastatic capability, and chemotherapeutic resistance. Mitophagy, or selective autophagy of mitochondria, can influence both the efficacy of tumor chemotherapy and the degree of drug resistance. Regardless of the fact that mitochondria are well-known for coordinating ATP synthesis from cellular respiration in cellular bioenergetics, little is known its mitophagy regulation in chemoresistance. Recent advancements in mitochondrial research, mitophagy regulatory mechanisms, and their implications for our understanding of chemotherapy resistance are discussed in this review.

Abstract

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. One of the well-known mechanisms of chemotherapy resistance is the change in the mitochondrial death pathways which occur when cells are under stressful situations, such as chemotherapy. Mitophagy, or mitochondrial selective autophagy, is critical for cell quality control because it can efficiently break down, remove, and recycle defective or damaged mitochondria. As cancer cells use mitophagy to rapidly sweep away damaged mitochondria in order to mediate their own drug resistance, it influences the efficacy of tumor chemotherapy as well as the degree of drug resistance. Yet despite the importance of mitochondria and mitophagy in chemotherapy resistance, little is known about the precise mechanisms involved. As a consequence, identifying potential therapeutic targets by analyzing the signal pathways that govern mitophagy has become a vital research goal. In this paper, we review recent advances in mitochondrial research, mitophagy control mechanisms, and their implications for our understanding of chemotherapy resistance.

The inhibitory effect and mechanism of quetiapine on tumor progression in hepatocellular carcinoma in vivo

Hepatocellular carcinoma (HCC) is the primary tumor of the liver and the fourth leading cause of cancer-related death. Recently, several studies indicated the anti-tumor potential of antipsychotic medicine. Quetiapine, an atypical antipsychotic, is used to treat schizophrenia, bipolar disorder, and major depressive disorder since 1997. However, whether quetiapine may show potential to suppress HCC progression and its underlying mechanism is persisting unclear. Quetiapine has been shown to induce apoptosis and inhibit invasion ability in HCC in vitro. Here, we established two different HCC (Hep3B, SK-Hep1) bearing animals to identify the treatment efficacy of quetiapine. Tumor growth, signaling transduction, and normal tissue pathology after quetiapine treatment were validated by caliper, bioluminescence image, immunohistochemistry (IHC), and hematoxylin and eosin staining, respectively. Quetiapine suppressed HCC progression in a dose-dependent manner. Extracellular signal-regulated kinases (ERKs) and Nuclear factor-κB (NF-κB) mediated downstream proteins, such as myeloid leukemia cell differentiation protein (MCL-1), cellular FLICE-inhibitory protein (C-FLIP), X-linked inhibitor of apoptosis protein (XIAP), Cyclin-D1, matrix metallopeptidase 9 (MMP-9), vascular endothelial growth factor-A (VEGF-A) and indoleamine 2,3-dioxygenase (IDO) which involved in proliferation, survival, angiogenesis, invasion and anti-tumor immunity were all decreased by quetiapine. In addition, extrinsic/intrinsic caspase-dependent and caspase-independent pathways, including cleaved caspase-3, -8, and - 9 were increased by quetiapine. In sum, the tumor inhibition that results from quetiapine may associate with ERK and NF-κB inactivation.

Development of an Autophagy-Based and Stemness-Correlated Prognostic Model for Hepatocellular Carcinoma Using Bulk and Single-Cell RNA-Sequencing

Accumulating evidence has proved that autophagy serves as a tumor promoter in formed malignancies, and the autophagy-related prognostic signatures have been constructed as clinical tools to predict prognosis in many high-mortality cancers. Autophagy-related genes have participated in the development and metastasis of hepatocellular carcinoma (HCC), but the understanding of their prognostic value is limited. Thereafter, LIMMA and survival analysis were conducted in both ICGC and TCGA databases and a total of 10 hub autophagy-related genes, namely, NPC1, CDKN2A, RPTOR, SPHK1, HGS, BIRC5, SPNS1, BAK1, ATIC, and MAPK3, were collected. Then, GO, KEGG, correlation, consensus, and PCA analyses were utilized to reveal their potential targeted role in HCC treatment. Single-cell RNA-seq of cancer stem cells also indicated that there was a positive correlation between these genes and stemness. In parallel, we applied univariate, LASSO, and multivariate regression analyses to study the autophagy-related genes and finally proposed that ATIC and BIRC5 were the valuable prognostic indicators of HCC. The signature based on ATIC and BIRC5 exhibited moderate power for predicting the survival of HCC in the ICGC cohort, and its efficacy was further validated in the TCGA cohort. Taken together, we suggested that 10 aforementioned hub genes are promising therapeutic targets of HCC and the ATIC/BIRC5 prognostic signature is a practical prognostic indicator for HCC patients.

Biofunctional magnesium-coated Ti6Al4V scaffolds promote autophagy-dependent apoptosis in osteosarcoma by activating the AMPK/mTOR/ULK1 signaling pathway

The recurrence of osteosarcoma (OS) after reconstruction using Ti6Al4V prostheses remains a major problem in the surgical treatment of OS. Modification of the surfaces of Ti6Al4V prostheses with antitumor functions is an important strategy for improving therapeutic outcomes. Magnesium (Mg) coating has been shown to be multifunctional: it exhibits osteogenic and angiogenic properties and the potential to inhibit OS. In this study, we determined the proper concentration of released Mg²⁺ with respect to OS inhibition and biosafety and evaluated the anti-OS effects of Mg-coated Ti6Al4V scaffolds. We found that the release of Mg²⁺ during short-term and long-term degradation could significantly inhibit the proliferation and migration of HOS and 143B cells. Increased cell apoptosis and excessive autophagy were also observed, and further evidence of AMPK/mTOR/ULK1 signaling pathway activation was obtained both in vitro and in vivo, which suggested that the biofunctional scaffolds induce OS inhibition. Our study demonstrates the ability of an Mg coating to inhibit OS and may contribute to the further application of Mg-coated Ti6Al4V prostheses.

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Multifunctional Mg coating is considerable surface modification for Ti6Al4V prostheses.

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Mg²⁺ releasing by the scaffolds could significantly inhibit the proliferation and migration of OS cells.

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The biofunctional scaffolds could inhibit OS by activating autophagy-dependent apoptosis.

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The AMPK/mTOR/ULK-1 pathway was involved in autophagy-depended apoptosis induced by the scaffolds.

p53-Induced Autophagy Regulates Chemotherapy and Radiotherapy Resistance in Multidrug Resistance Cancer Cells

Background

Multidrug resistance (MDR), a major problem in oncology therapy, limits the effectiveness of anticancer drugs. Although p53 functions as a tumor suppressor, the associations between p53 status, autophagy, and MDR are complicated and conditional.

Method

 In this report, p53-null human ovarian cancer cell line SKOV3 and its MDR phenotype SKVCR and human leukemia cell line CEM and its MDR phenotype CEM-VLB) (p53 mutant cell line) were used.

Results

 Compared to parental SKOV3, the mRNA and protein levels of MAPLC3-II and Beclin1 were higher in SKVCR cells. The inhibition of autophagy by 3-MA significantly sensitized SKVCR to VCR. Conversely, in drug-resistant leukemic cells CEM-VLB, the expressions of Beclin1 and MAPLC3-II were lower than CEM. CEM and CEM-VLB cells were treated with VLB .01 or 0.5 μg/mL, respectively, and the expression of p53 and autophagy up-regulated after VLB (.01 μg/mL) treatment in CEM cells. The percentage of S-phase and G2/M phase cells up-regulated significantly by .01 μg/mL VLB in CEM, which may relate to the status of p53 of CEM cells. A combination of radiation with 3-MA significantly increased apoptosis in CEM-VLB cells.

Conclusion

 Our discovery found that p53 is an important regulator controlling the balance between autophagy and MDR, as a potential drug target for ovarian cancer and leukemia.

Analysis of microRNA expression in CD133 positive cancer stem‑like cells of human osteosarcoma cell line MG-63

Osteosarcoma (OS) is a primary malignant tumor of bone occurring in young adults. OS stem cells (OSCs) play an important role in the occurrence, growth, metastasis, drug resistance and recurrence of OS. CD133 is an integral membrane glycoprotein, which has been identified as an OSC marker. However, the mechanisms of metastasis, chemoresistance, and progression in CD133(+) OSCs need to be further explored. In this study, we aim to explore differences in miRNA levels between CD133(+) and CD133(-) cells from the MG-63 cell line. We found 20 differentially expressed miRNAs (DEmiRNAs) (16 upregulated and 4 downregulated) in CD133(+) cells compared with CD133(-) cells. Hsa-miR-4485-3p, hsa-miR-4284 and hsa-miR-3656 were the top three upregulated DEmiRNAs, while hsa-miR-487b-3p, hsa-miR-493-5p and hsa-miR-431-5p were the top three downregulated DEmiRNAs. In addition, RT-PCR analysis confirmed that the expression levels of hsa-miR-4284, hsa-miR-4485-3p and hsa-miR-3656 were significantly increased, while the expression levels of hsa-miR-487b-3p, hsa-miR-493-5p, and hsa-miR-431-5p were significantly decreased in CD133(+) cells compared with CD133(-) cells. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that predicted or validated target genes for all 20 DEmiRNAs or the selected 6 DEmiRNAs participated in the "PI3K-Akt signaling pathway," "Wnt signaling pathway," "Rap1 signaling pathway," "Cell cycle" and "MAPK signaling pathway". Among the selected six DEmiRNAs, miR-4284 was especially interesting. MiR-4284 knockdown significantly reduced the sphere forming capacity of CD133(+) OS cells. The number of invasive CD133(+) OS cells was markedly decreased after miR-4284 knockdown. In addition, miR-4284 knockdown increased the p-β-catenin levels in CD133(+) OS cells. In conclusion, RNA-seq analysis revealed DEmiRNAs between CD133(+) and CD133(-) cells. MiRNAs might play significant roles in the function of OSCs and could serve as targets for OS treatment. MiR-4284 prompted the self-renewal and invasion of OSCs. The function of miR-4284 might be associated with the Wnt signaling pathway.

Role of Autophagy in the Maintenance of Stemness in Adult Stem Cells: A Disease-Relevant Mechanism of Action

Autophagy is an intracellular scavenging mechanism induced to eliminate damaged, denatured, or senescent macromolecular substances and organelles in the body. The regulation of autophagy plays essential roles in the processes of cellular homeostasis and senescence. Dysregulated autophagy is a common feature of several human diseases, including cancers and neurodegenerative disorders. The initiation and development of these disorders have been shown to be associated with the maintenance of disease-specific stem cell compartments. In this review, we summarize recent advances in our understanding of the role of autophagy in the maintenance of stemness. Specifically, we focus on the intersection between autophagy and adult stem cells in the initiation and progression of specific diseases. Accordingly, this review highlights the role of autophagy in stemness maintenance from the perspective of disease-associated mechanisms, which may be fundamental to our understanding of the pathogeneses of human diseases and the development of effective therapies.

Cancer Stem Cells as a Source of Drug Resistance in Bone Sarcomas

Bone sarcomas are commonly characterized by a high degree of intra-tumor heterogeneity, which in part is due to the presence of subpopulations of tumor cells presenting stem cell properties. Similar to normal stem cells, these cancer stem cells (CSCs) display a drug resistant phenotype and therefore are responsible for relapses and tumor dissemination. Drug resistance in bone sarcomas could be enhanced/modulated during tumor evolution though the acquisition of (epi)-genetic alterations and the adaptation to changing microenvironments, including drug treatments. Here we summarize findings supporting the involvement of pro-stemness signaling in the development of drug resistance in bone sarcomas. This include the activation of well-known pro-stemness pathways (Wnt/β-Cat, NOTCH or JAT/STAT pathways), changes in the metabolic and autophagic activities, the alteration of epigenetic pathways, the upregulation of specific non-coding RNAs and the crosstalk with different microenvironmental factors. This altered signaling is expected to be translated to the clinic in the form of biomarkers of response and new therapies able to overcome drug resistance.

Autophagy Blockade by Ai Du Qing Formula Promotes Chemosensitivity of Breast Cancer Stem Cells Via GRP78/β-Catenin/ABCG2 Axis

Accumulating evidence suggests that the root of drug chemoresistance in breast cancer is tightly associated with subpopulations of cancer stem cells (CSCs), whose activation is largely dependent on taxol-promoting autophagy. Our pilot study identified GRP78 as a specific marker for chemoresistance potential of breast CSCs by regulating Wnt/β-catenin signaling. Ai Du Qing (ADQ) is a traditional Chinese medicine formula that has been utilized in the treatment cancer, particularly during the consolidation phase. In the present study, we investigated the regulatory effects and molecular mechanisms of ADQ in promoting autophagy-related breast cancer chemosensitivity. ADQ with taxol decreasing the cell proliferation and colony formation of breast cancer cells, which was accompanied by suppressed breast CSC ratio, limited self-renewal capability, as well as attenuated multi-differentiation. Furthermore, autophagy in ADQ-treated breast CSCs was blocked by taxol via regulation of β-catenin/ABCG2 signaling. We also validated that autophagy suppression and chemosensitizing activity of this formula was GRP78-dependent. In addition, GRP78 overexpression promoted autophagy-inducing chemoresistance in breast cancer cells by stabilizing β-catenin, while ADQ treatment downregulated GRP78, activated the Akt/GSK3β-mediated proteasome degradation of β-catenin via ubiquitination activation, and consequently attenuated the chemoresistance-promoted effect of GRP78. In addition, both mouse breast cancer xenograft and zebrafish xenotransplantation models demonstrated that ADQ inhibited mammary tumor growth, and the breast CSC subpopulation showed obscure adverse effects. Collectively, this study not only reveals the chemosensitizating mechanism of ADQ in breast CSCs, but also highlights the importance of GRP78 in mediating autophagy-promoting drug resistance via β-catenin/ABCG2 signaling.

Bone and Soft Tissue Tumors: New Treatment Approaches

Bone and soft tissue sarcomas require intensive treatments, including chemotherapy, surgical resection with safe margin, and radiotherapy [...].