Autophagy prevents doxorubicin‑induced apoptosis in osteosarcoma

Mechanistic insights into carvedilol's potential protection against doxorubicin-induced cardiotoxicity

Doxorubicin (DOX) is an anthracycline chemotherapy drug widely employed in the treatment of various cancers, known for its potent antineoplastic properties but often associated with dose-dependent cardiotoxicity, limiting its clinical use. This review explores the complex molecular details that determine the heart-protective effectiveness of carvedilol in relation to cardiotoxicity caused by DOX. The harmful effects of DOX on heart cells could include oxidative stress, DNA damage, iron imbalance, disruption of autophagy, calcium imbalance, apoptosis, dysregulation of topoisomerase 2-beta, arrhythmogenicity, and inflammatory responses. This review carefully reveals how carvedilol serves as a strong protective mechanism, strategically reducing each aspect of cardiac damage caused by DOX. Carvedilol's antioxidant capabilities involve neutralizing free radicals and adjusting crucial antioxidant enzymes. It skillfully manages iron balance, controls autophagy, and restores the calcium balance essential for cellular stability. Moreover, the anti-apoptotic effects of carvedilol are outlined through the adjustment of Bcl-2 family proteins and activation of the Akt signaling pathway. The medication also controls topoisomerase 2-beta and reduces the renin-angiotensin-aldosterone system, together offering a thorough defense against cardiotoxicity induced by DOX. These findings not only provide detailed understanding into the molecular mechanisms that coordinate heart protection by carvedilol but also offer considerable potential for the creation of targeted treatment strategies intended to relieve cardiotoxicity caused by chemotherapy.

Label-free fluorescence lifetime imaging for the assessment of cell viability in living tumor fragments

Significance

To enable non-destructive longitudinal assessment of drug agents in intact tumor tissue without the use of disruptive probes, we have designed a label-free method to quantify the health of individual tumor cells in excised tumor tissue using multiphoton fluorescence lifetime imaging microscopy (MP-FLIM).

Aim

Using murine tumor fragments which preserve the native tumor microenvironment, we seek to demonstrate signals generated by the intrinsically fluorescent metabolic co-factors nicotinamide adenine dinucleotide phosphate [NAD(P)H] and flavin adenine dinucleotide (FAD) correlate with irreversible cascades leading to cell death.

Approach

We use MP-FLIM of NAD(P)H and FAD on tissues and confirm viability using standard apoptosis and live/dead (Caspase 3/7 and propidium iodide, respectively) assays.

Results

Through a statistical approach, reproducible shifts in FLIM data, determined through phasor analysis, are shown to correlate with loss of cell viability. With this, we demonstrate that cell death achieved through either apoptosis/necrosis or necroptosis can be discriminated. In addition, specific responses to common chemotherapeutic treatment inducing cell death were detected.

Conclusions

These data demonstrate that MP-FLIM can detect and quantify cell viability without the use of potentially toxic dyes, thus enabling longitudinal multi-day studies assessing the effects of therapeutic agents on tumor fragments.

Lnc-ing epigenetic mechanisms with autophagy and cancer drug resistance

Long noncoding RNAs (lncRNAs) comprise a diverse class of RNA molecules that regulate various physiological processes and have been reported to be involved in several human pathologies ranging from neurodegenerative disease to cancer. Therapeutic resistance is a major hurdle for cancer treatment. Over the past decade, several studies has emerged on the role of lncRNAs in cancer drug resistance and many trials have been conducted employing them. LncRNAs also regulate different cell death pathways thereby maintaining a fine balance of cell survival and death. Autophagy is a complex cell-killing mechanism that has both cytoprotective and cytotoxic roles. Similarly, autophagy can lead to the induction of both chemosensitization and chemoresistance in cancer cells upon therapeutic intervention. Recently the role of lncRNAs in the regulation of autophagy has also surfaced. Thus, lncRNAs can be used in cancer therapeutics to alleviate the challenges of chemoresistance by targeting the autophagosomal axis. In this chapter, we discuss about the role of lncRNAs in autophagy-mediated cancer drug resistance and its implication in targeted cancer therapy.

Cultivation, nutritional value, bioactive compounds of morels, and their health benefits: A systematic review

Morels are valuable mushrooms being used as foods and medical substances for a long history. The commonly cultivated morel species include M. eximia, M. importuna, and M. sextelata in China, M. conica and M. esculenta in the US. Morels' nutritional profile mainly consists of carbohydrates, proteins, fatty acids, vitamins, minerals, and organic acids, which are also responsible for its complex sensory attributes and health benefits. The bioactive compounds in morels including polysaccharides, phenolics, tocopherols, and ergosterols contribute to the anti-oxidative abilities, anti-inflammation, immunoprotection, gut health preservation, and anti-cancer abilities. This review depicted on the cultivation of morels, major bioactive compounds of different morel species both from fruit bodies and mycelia, and their health benefits to provide a comprehensive understanding of morels and support the future research and applications of morels as high-value functional food sources.

Doxorubicin-An Agent with Multiple Mechanisms of Anticancer Activity

Doxorubicin (DOX) constitutes the major constituent of anti-cancer treatment regimens currently in clinical use. However, the precise mechanisms of DOX's action are not fully understood. Emerging evidence points to the pleiotropic anticancer activity of DOX, including its contribution to DNA damage, reactive oxygen species (ROS) production, apoptosis, senescence, autophagy, ferroptosis, and pyroptosis induction, as well as its immunomodulatory role. This review aims to collect information on the anticancer mechanisms of DOX as well as its influence on anti-tumor immune response, providing a rationale behind the importance of DOX in modern cancer therapy.

DNMT2/TRDMT1 gene knockout compromises doxorubicin-induced unfolded protein response and sensitizes cancer cells to ER stress-induced apoptosis

The acidic, hypoxic and nutrient-deprived tumor microenvironment may induce endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) may exert an important cytoprotective role by promoting folding of newly synthesized proteins and cancer cell survival. The lack of DNMT2/TRDMT1 methyltransferase-mediated C38 tRNA methylation compromises translational fidelity that may result in the accumulation of misfolded and aggregated proteins leading to proteotoxic stress-related cell death. In the present study, DNMT2/TRDMT1 gene knockout-mediated effects were investigated during doxorubicin (DOX)-induced ER stress and PERK-, IRE1- and ATF6-orchestrated UPR in four genetically different cellular models of cancer (breast and cervical cancer, osteosarcoma and glioblastoma cells). Upon DOX stimulation, DNMT2/TRDMT1 gene knockout impaired PERK activation and modulated NSUN and 5-methylcytosine RNA-based responses and microRNA profiles. The lack of DNMT2/TRDMT1 gene in DOX-treated four cancer cell lines resulted in decreased levels of four microRNAs, namely, miR-23a-3p, miR-93-5p, miR-125a-5p and miR-191-5p involved in the regulation of several pathways such as ubiquitin-mediated proteolysis, amino acid degradation and translational misregulation in cancer. We conclude that DNMT2/TRDMT1 gene knockout, at least in selected cellular cancer models, affects adaptive responses associated with protein homeostasis networks that during prolonged ER stress may result in increased sensitivity to apoptotic cell death.

LncRNA FGD5-AS1 potentiates autophagy-associated doxorubicin resistance by regulating the miR-154-5p/WNT5A axis in osteosarcoma

Osteosarcoma is prevalent in children and adolescent. The oncogenic function of long-chain noncoding RNA (lncRNA) FGD5 antisense RNA 1 (FGD5-AS1) has been reported. However, the function of FGD5-AS1 in doxorubicin-resistance in osteosarcoma remains to be illucidated. Quantitative real-time PCR (qRT-PCR) and western blot analysis (WB) were used to measure the expression of FGD5-AS1, miR-154-5p, WNT5A and autophagy proteins. MTT assay was used to assess cell viability and transwell assay was performed to evaluate migration. A nude mouse xenograft model was developed to verify the function of FGD5-AS1 in vivo. FGD5-AS1 was upregulated in doxorubicin-resistant (DXR) osteosarcoma cells. Knockdown of FGD5-AS1 suppressed osteosarcoma cell proliferation, migration, and autophagy. FGD5-AS1 upregulated WNT5A expression via sponging miR-154-5p. Furthermore, FGD5-AS1 enhanced osteosarcoma cell chemotherapy resistance through upregulation of WNT5A by inhibiting miR-154-5p. Suppression of FGD5-AS1 significantly suppressed tumor growth in nude mice. FGD5-AS1 may promote chemoresistance through WNT5A-induced autophagy by sponging miR-154-5p in osteosarcoma cells.

Shape-memory balloon offering simultaneous thermo/chemotherapies to improve anti-osteosarcoma efficacy

This paper proposes a shape-memory balloon (SMB) to improve bone cement injection efficiency and postoperative thermo/chemotherapy for bone tumors. The SMB consists of biodegradable poly(ε-caprolactone) (PCL), an anticancer drug (doxorubicin, DOX), and heat-generating magnetic nanoparticles (MNPs). The balloon shape is fabricated in a mold by crosslinking PCL macromonomers with DOX and MNPs. The mechanical properties and shape-transition temperature (approximately 40 °C) of the SMB are modulated by adjusting the molecular weight of PCL and the crosslinking density. This allows safe inflation at the affected site with a 400% expansion rate by simple blow molding. The expanded shape is temporarily memorized at 37 °C, and the computed tomography image shows that the bone cement is successfully injected without extra pressure or leakage. The SMB releases DOX for over 4 weeks, allowing a prolonged effect at the local site. The local dosing is constant as the medication is continuously released, demonstrating an ON-OFF switchable heating/cooling response to alternating magnetic field irradiation. In vitro cytotoxic studies have demonstrated that heat generation/drug release and only drug release from the balloon kill approximately 99% and 60% of human osteosarcoma cells, respectively. The proposed SMB is promising in postoperative local thermo/chemotherapy for bone tumors.

The lack of functional DNMT2/TRDMT1 gene modulates cancer cell responses during drug-induced senescence

Cellular senescence may be a side effect of chemotherapy and other anti-cancer treatments that may promote inflammation and paracrine secondary senescence in healthy tissues. DNMT2/TRDMT1 methyltransferase is implicated in the regulation of cellular lifespan and DNA damage response (DDR). In the present study, the responses to senescence inducing concentrations of doxorubicin and etoposide in different cancer cells with DNMT2/TRDMT1 gene knockout were evaluated, namely changes in the cell cycle, apoptosis, autophagy, interleukin levels, genetic stability and DDR, and 5-mC and NSUN1-6 levels. Moreover, the effect of azacytidine post-treatment was considered. Diverse responses were revealed that was based on type of cancer cells (breast and cervical cancer, osteosarcoma and glioblastoma cells) and anti-cancer drugs. DNMT2/TRDMT1 gene knockout in drug-treated glioblastoma cells resulted in decreased number of apoptotic and senescent cells, IL-8 levels and autophagy, and increased number of necrotic cells, DNA damage and affected DDR compared to drug-treated glioblastoma cells with unmodified levels of DNMT2/TRDMT1. We suggest that DNMT2/TRDMT1 gene knockout in selected experimental settings may potentiate some adverse effects associated with chemotherapy-induced senescence.

White light emitting diode induces autophagy in hippocampal neuron cells through GSK-3-mediated GR and RORα pathways

Autophagy plays an important role in cell survival under diverse stress conditions. Here, we show that white LED light exposure for 24 h significantly activated autophagy-related genes and increased autophagosome formation in hippocampal neural cells (HT-22). Concurrently, the rhythmic pattern of clock-related gene expression was disrupted, which was associated with augmented expression of SIRT1, AMPK and retinoid-related orphan receptor alpha (RORα). SR1001, a specific inhibitor of RORα, protected the cells from light-induced activation of autophagy. Moreover, light exposure increased glucocorticoid receptor (GR) phosphorylation and nuclear translocation. GR inhibitor RU486 prevented light-induced up-regulation of RORα and the activation of autophagy. These changes were associated with enhanced glycogen synthase kinase-3 (GSK-3) activity and its specific inhibitor CHIR-99021 significantly rescued light-induced autophagy and augmented GR, RORα and autophagy-related proteins. Furthermore, GSK-3 was identified as an upstream regulator of GR/RORα signaling as it was not affected by GR or RORα inhibitors. Taken together, our data demonstrate that GSK-3-mediated GR/RORα signaling pathway is involved in white LED light-induced autophagy in hippocampal neuron cells.

LncRNA Sox2OT-V7 promotes doxorubicin-induced autophagy and chemoresistance in osteosarcoma via tumor-suppressive miR-142/miR-22

Doxorubicin (Dox) is one of the most commonly used chemotherapeutic drugs for osteosarcoma (OS) treatment. In the present study, we attempted to investigate the mechanism by which Sox2OT-V7 dysregulation affects Dox chemoresistance to provide a novel experimental basis for developing neoadjuvant therapy. Sox2OT-V7 expression is upregulated in OS tissues, particularly in chemoresistant OS tissues, and in OS cell lines compared to controls. Dox treatment induces autophagy and Sox2OT-V7 expression in U2OS cells, and Dox-induced autophagy is partially attenuated by Sox2OT-V7 silencing. Knocking down Sox2OT-V7 or blocking autophagy in Dox-resistant U2OS/Dox cells resensitizes the cells to Dox treatment in vitro. Moreover, Sox2OT-V7 directly targets miR-142/miR-22 to inhibit their expression, and the effect of Sox2OT-V7 silencing on U2OS cell autophagy and U2OS/Dox cell sensitivity to Dox can be reversed by miR-142/miR-22 inhibition. Sox2OT-V7 silencing enhances the suppressive effects of Dox on U2OS/Dox cell-derived tumor growth in vivo, while miR-22 inhibition or miR-142 inhibition reverses the effects of Sox2OT-V7 silencing on Dox-induced suppression on tumor growth. Finally, miR-142 directly targets ULK1, ATG4A, and ATG5, while miR-22 directly targets ULK1 to inhibit the expression of the target gene; The Sox2OT-V7/miR-142/miR-22 axis modulates autophagy in OS cells by regulating ULK1, ATG4A, and ATG5.

Combination of an Autophagy Inducer and an Autophagy Inhibitor: A Smarter Strategy Emerging in Cancer Therapy

Autophagy is considered a cytoprotective function in cancer therapy under certain conditions and is a drug resistance mechanism that represents a clinical obstacle to successful cancer treatment and leads to poor prognosis in cancer patients. Because certain clinical drugs and agents in development have cytoprotective autophagy effects, targeting autophagic pathways has emerged as a potential smarter strategy for cancer therapy. Multiple preclinical and clinical studies have demonstrated that autophagy inhibition augments the efficacy of anticancer agents in various cancers. Autophagy inhibitors, such as chloroquine and hydroxychloroquine, have already been clinically approved, promoting drug combination treatment by targeting autophagic pathways as a means of discovering and developing more novel and more effective cancer therapeutic approaches. We summarize current studies that focus on the antitumor efficiency of agents that induce cytoprotective autophagy combined with autophagy inhibitors. Furthermore, we discuss the challenge and development of targeting cytoprotective autophagy as a cancer therapeutic approach in clinical application. Thus, we need to facilitate the exploitation of appropriate autophagy inhibitors and coadministration delivery system to cooperate with anticancer drugs. This review aims to note optimal combination strategies by modulating autophagy for therapeutic advantage to overcome drug resistance and enhance the effect of antitumor therapies on cancer patients.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.

Expression of the double-stranded RNA-dependent kinase PKR influences osteosarcoma attachment independent growth, migration, and invasion

Osteosarcoma (OS) is a rare, insidious tumor of mesenchymal origin that most often affects children, adolescents, and young adults. While the primary tumor can be controlled with chemotherapy and surgery, it is the lung metastases that are eventually fatal. Multiple studies into the initial drivers of OS development have been undertaken, but few of these have examined innate immune/inflammatory signaling. A central figure in inflammatory signaling is the innate immune/stress-activated kinase double-stranded RNA-dependent protein kinase (PKR). To characterize the role of PKR in OS, U2OS, and SaOS-2 osteosarcoma cell lines were stably transfected with wild-type or dominant-negative (DN) PKR. Overexpression of PKR enhanced colony formation in soft agar (U2OS and SaOS-2), enhanced cellular migration (U2OS), and invasive migration (SaOS-2). In contrast, overexpression of DN-PKR inhibited attachment-independent growth, migration and/or invasion. These data demonstrate a role for inflammatory signaling in OS formation and migration/invasion and suggest the status of PKR expression/activation may have prognostic value.

Emodin induces apoptosis and autophagy of fibroblasts obtained from patient with ankylosing spondylitis

Background

Ankylosing spondylitis (AS) is a type of rheumatoid disease, which has been reported to be associated with the excessive proliferation of fibroblasts recently. Emodin, a single component from a traditional Chinese medicine Rheum palmatum, exerts anti-inflammation and antirheumatic arthritis activities. However, could emodin be used to treat AS remains unclear? Thus, this study aimed to investigate the effect of emodin on AS.

Methods

Fibroblasts obtained from patients with AS were used in the current study. In addition, multiple cellular and molecular biology techniques such as Cell Counting Kit-8, Western blotting, flow cytometry, monodansylcadaverine staining, and immunofluorescence assay were applied as well.

Results

Emodin-induced apoptosis of fibroblasts obtained from patient with AS via increasing active caspase-9, active caspase-3, and Bax levels and downregulating Bcl-2. Meanwhile, emodin enhanced autophagy in fibroblasts via upregulation of the expression of Atg12, Atg5, and Beclin 1, which was further confirmed by monodansylcadaverine staining. As expected, autophagy inhibitor 3-methyladenine (3MA) completely reversed emodin-induced autophagy in fibroblasts. Moreover, 3MA significantly increased emodin-induced apoptosis of fibroblasts obtained from patient with AS by increasing the levels of γH2AX, active caspase-9, active caspase-3, and cleaved poly ADP-ribose polymerase.

Conclusion

Our results indicated that emodin effectively induced apoptosis and autophagy of fibroblasts obtained from patient with AS. In addition, suppression of autophagy enhanced emodin-induced apoptosis in fibroblasts. Therefore, we proposed that combination of emodin with autophagy inhibitor might be a potent strategy for improving the symptoms of AS in the future.

Drug resistance-related microRNAs in osteosarcoma: Translating basic evidence into therapeutic strategies

Although the application of multiple chemotherapy brought revolutionary changes to improve overall survival of osteosarcoma patients, the existence of multidrug resistance (MDR) has become a great challenge for successful osteosarcoma treatment in recent decades. Substantial studies have revealed various underlying mechanisms of MDR in cancers. As for osteosarcoma, evidence has highlighted that microRNAs (miRNAs) can mediate in the processes of DNA damage response, apoptosis avoidance, autophagy induction, activation of cancer stem cells, and signal transduction. Besides, these drug resistance‐related miRNAs showed much promise for serving as candidates for predictive biomarkers of poor outcomes and shorter survival time, and therapeutic targets to reverse drug resistance and overcome treatment refractoriness. This review aims to demonstrate the potential molecular mechanisms of miRNAs‐regulated drug resistance in osteosarcoma, and provide insight in translating basic evidence into therapeutic strategies.

Autophagy induced by low concentrations of crotonaldehyde promotes apoptosis and inhibits necrosis in human bronchial epithelial cells

Crotonaldehyde is a common environmental contaminant. Autophagy, apoptosis, and necrosis, were all respectively reported to be induced by crotonaldehyde. However, the relationships between programmed cell deaths, especially between autophagy and apoptosis, have not been elucidated. In the present study, alterations of autophagy, apoptosis and necrosis were investigated in human bronchial epithelial cells (BEAS-2B) exposed to crotonaldehyde, and effects of autophagy on apoptosis and necrosis were detected. We found that a high concentration (160 μmol/L, μM) of crotonaldehyde did not induce apoptosis, while a low concentration (80 μM) of crotonaldehyde induced autophagy, apoptosis and necrosis. In 80 μM crotonaldehyde-exposed BEAS-2B cells, autophagy and apoptosis exhibited a trend of increasing prior to decreasing with the increase of time, while the time point inducing the highest level of autophagy was 2 h, and that of apoptosis was 4 h. With the pretreatment of bafilomycin A₁, the apoptosis was inhibited and the necrosis was enhanced significantly in cells exposed to 80 μM crotonaldehyde. Autophagy mediated the induction of apoptosis via the intrinsic apoptotic pathway. The results indicate that autophagy mediates the initiation of apoptosis and plays a role in protecting from necrosis in low concentrations of crotonaldehyde-exposed BEAS-2B cells.

The autophagy inhibitor spautin-1, either alone or combined with doxorubicin, decreases cell survival and colony formation in canine appendicular osteosarcoma cells

Dogs diagnosed with appendicular osteosarcoma typically succumb to metastatic disease within a year of diagnosis. The current standard of care for curative intent, amputation followed by adjuvant chemotherapy, increases survival time but chemoresistance is a major contributor to mortality. Unfortunately, the mechanisms driving the progression of metastatic disease and the development of chemoresistance are unknown. One theory is that autophagy may contribute to chemoresistance by providing neoplastic cells with a mechanism to survive chemotherapy treatment. Our objective was to evaluate the effect of combining an autophagy inhibitor with a standard chemotherapeutic drug on response to chemotherapy in canine appendicular osteosarcoma cells. We hypothesized that combining the autophagy inhibitor spautin-1 with doxorubicin treatment would enhance chemoresponsiveness. Using commercial (D17) and primary cell lines derived from 1° and 2° sites of osteosarcoma, we showed that this combination treatment enhances cell killing and inhibits colony formation. Our findings support the theory that autophagy contributes to chemoresistance in canine appendicular osteosarcoma and indicate that adding an autophagy inhibitor to the standard of care has the potential to improve outcome.

PG-Priming Enhances Doxorubicin Influx to Trigger Necrotic and Autophagic Cell Death in Oral Squamous Cell Carcinoma

Synergistic effects between natural compounds and chemotherapy drugs are believed to have fewer side effects with equivalent efficacy. However, the synergistic potential of prodigiosin (PG) with doxorubicin (Dox) chemotherapy is still unknown. This study explores the synergistic mechanism of PG and Dox against oral squamous cell carcinoma (OSCC) cells. Three OSCC cell lines were treated with different PG/Dox combinatory schemes for cytotoxicity tests and were further investigated for cell death characteristics by cell cycle flow cytometry and autophagy/apoptosis marker labelling. When OSCC cells were pretreated with PG, the cytotoxicity of the subsequent Dox-treatment was 30% higher than Dox alone. The cytotoxic efficacy of PG-pretreated was found better than those of PG plus Dox co-treatment and Dox-pretreatment. Increase of Sub-G1 phase and caspase-3/LC-3 levels without poly (ADP-ribose) polymeras (PARP) elevation indicated both autophagy and necrosis occurred in OSCC cells. Dox flux after PG-priming was further evaluated by rhodamine-123 accumulation and Dox transporters analysis to elucidate the PG-priming effect. PG-priming autophagy enhanced Dox accumulation according to the increase of rhodamine-123 accumulation without the alterations of Dox transporters. Additionally, the cause of PG-triggered autophagy was determined by co-treatment with endoplasmic reticulum (ER) stress or AMP-activated protein kinase (AMPK) inhibitor. PG-induced autophagy was not related to nutrient deprivation and ER stress was proved by co-treatment with specific inhibitor. Taken together, PG-priming autophagy could sensitize OSCC cells by promoting Dox influx without regulation of Dox transporter. The PG-priming might be a promising adjuvant approach for the chemotherapy of OSCC.

Development of a Novel Autophagy-related Prognostic Signature for Serous Ovarian Cancer

Purpose: Considerable evidence suggests that autophagy plays a crucial role in the biological processes of ovarian cancer. The aim of this study was to develop a novel autophagy-related prognostic signature for serous ovarian cancer.

Methods: A univariate Cox proportional regression model was used to analyze mRNA microarray and clinical data in The Cancer Genome Atlas (TCGA) for the purpose of selecting autophagy-related prognostic genes. A multivariate Cox proportional regression model and the survival analysis were used to develop an eight-gene prognostic signature. The multivariate Cox and stratification analysis suggested that this signature was an independent prognostic factor for serous ovarian cancer patients. Bioinformatics functions were investigated by a principal components analysis and gene set enrichment analysis (GSEA). Finally, the correlation between the prognostic signature and gene mutation status was further analyzed in serous ovarian cancer, and especially with regard to the mutation status of BRCA1 and BRCA2 (BRCA1/2) genes.

Results: Distinctly different autophagy-related gene expression profiles were identified in normal ovarian tissues and serous ovarian cancer tissues. We profiled an autophagy-related gene set and identified eight genes with significant prognostic values for serous ovarian cancer. Subsequently, an autophagy-related ovarian cancer risk signature was constructed, and patients at a high-risk or low-risk for poor prognosis were identified based on their signature. High-risk patients had significantly shorter overall survival (OS) and disease-free survival (DFS) times than low-risk patients. GSEA results suggested an enhanced intensity of autophagy regulation in high-risk patients when compared with low-risk patients. When studied as an independent prognostic factor for serous ovarian cancer, the significant prognostic value of this signature could be seen in the stratified cohorts. For clinical use, we developed a nomogram that included the prognostic classifier and seven clinical risk factors. Additionally, we identified the 10 most frequently mutated genes found in serous ovarian cancer patients, and analyzed them for their differences in high-risk and low-risk patients. Among 293 patients, 62 had BRCA1/2 gene mutations, and this result was significantly correlated with the autophagy-related prognostic signature.

Conclusions: Our findings suggest that the eight-gene autophagy-related signature could serve as an independent prognostic indicator for cases of serous ovarian cancer.

Novel oxazolinoanthracyclines as tumor cell growth inhibitors-Contribution of autophagy and apoptosis in solid tumor cells death

Chemical modification of known, effective drugs are one method to improve the chemotherapy of tumors. We reported ability of oxazoline analogs of doxorubicin (O-DOX) and daunorubicin (O-DAU) to induce apoptosis and autophagy in ovarian and liver cancer cells. Reactive oxygen and nitrogen species (ROS and RNS, respectively), together with intracellular calcium-mediated downstream signaling, are essential for the anticancer effect of these new anthracycline analogs. The changes of mitochondrial membrane potential and induction of the ceramide pathway suggests that these compounds induce cell death by apoptosis. In addition, a significant increase of autophagosome formation was observed by fluorescence assay and acridine orange staining, indicating that the new analogs also induce autophagic cell death. Compared to free DOX- and DAU-treated cells, we observed inhibition of colony formation and migration, a time-dependency between ROS/RNS levels and a greater fall in mitochondrial membrane potential. Altogether, our research broadens the base of molecular oxazolinoanthracyclines targets and reveals that derivatives mediated oxidative stress, ceramide production and increase in intracellular calcium level by mitochondria. Furthermore, our data highlight the importance of mitochondria that simultaneously assume the role of activator of autophagy and apoptosis signals.

Analysis of HSP27 and the Autophagy Marker LC3B+ Puncta Following Preoperative Chemotherapy Identifies High-Risk Osteosarcoma Patients

Chemotherapy-induced autophagy is a proposed mechanism of chemoresistance and potential therapeutic target in osteosarcoma. We evaluated heat shock protein 27 (HSP27) and autophagy-related proteins as predictors of pathologic treatment response and prognostic markers among osteosarcoma patients who received standard chemotherapy. We analyzed 394 tumor specimens (pre-treatment, post-treatment, and metastases) from 260 osteosarcoma patients by immunohistochemistry for cytoplasmic light chain 3B (LC3B)-positive puncta, sequestosome 1 (SQSTM1), high mobility group box 1 (HMGB1), and HSP27 expression. The staining percentage and intensity for each marker were scored and the extent to which marker expression was correlated with pathologic response, relapse-free survival (RFS), and overall survival (OS) was assessed. LCB3+ puncta in post-treatment primary tumors (50%) and metastases (67%) was significantly higher than in pre-treatment biopsy specimens (30%; P = 0.023 and <0.001). Among 215 patients with localized osteosarcoma, both pre-treatment [multivariate hazard ratio (HR), 26.7; 95% confidence interval (CI), 1.47-484; P = 0.026] and post-treatment HSP27 expression (multivariate HR, 1.85; 95% CI, 1.03-3.33; P = 0.039) were associated with worse OS. Lack of LC3B+ puncta at resection was an independent poor prognostic marker in both univariate (HR, 1.78; 95% CI, 1.05-3.03; P = 0.034) and multivariate models (HR, 1.75; 95% CI, 1.01-3.04; P = 0.045). Patients with LC3B+/HSP27- tumors at resection had the best 10-year OS (75%) whereas patients with LC3B-/HSP27+ tumors had the worst 10-year survival (25%). Neither HSP27 expression nor the presence of LCB3+ puncta was correlated with pathologic treatment response. Our findings establish HSP27 expression and LC3B+ puncta as independent prognostic markers in osteosarcoma patients receiving standard chemotherapy and support further investigation into strategies targeting HSP27 or modulating autophagy in osteosarcoma treatment. Mol Cancer Ther; 17(6); 1315-23. ©2018 AACR.

Glucocorticoid-activated IRE1α/XBP-1s signaling: an autophagy-associated protective pathway against endotheliocyte damage

Glucocorticoid-induced endothelial injury has been reported in several diseases. Although there are several theories, the exact mechanism underlying the role of glucocorticoids in this process remains unclear. Autophagy has been reported to occur as a response to different stimuli and can affect cell survival and function. In this study, we found that glucocorticoids induced apoptosis and endoplasmic reticulum (ER) stress in endotheliocytes. Furthermore, we discovered that glucocorticoids induced autophagy in these cells and the inositol requiring protein 1 (IRE1α)/X-box binding protein 1s (XBP-1s) axis, one of the downstream signaling pathways of ER stress, was associated with the glucocorticoid-induced autophagy. The autophagy partly protected endotheliocytes from glucocorticoid-induced apoptosis and inhibition of proliferation. In conclusion, glucocorticoid-induced endoplasmic reticulum stress activated the IRE1α/XBP-1s signaling and induced autophagy, which, in turn, played a protective role in endotheliocyte survival and proliferation, avoiding further cellular damage caused by glucocorticoids.

Long non-coding RNA CTA sensitizes osteosarcoma cells to doxorubicin through inhibition of autophagy

Recently, several long non-coding RNAs (lncRNAs) have been implicated in osteosarcoma (OS). However, the regulatory roles of lncRNAs in chemotherapy resistance of OS still remain unclear. This study aimed to screen a novel lncRNA that contributes to chemotherapeutic resistance of OS, and to explore the underlying mechanisms. Our data showed that lncRNA CTA was markedly downregulated in OS tissues compared to their matched non-tumor tissues, and low expression of lncRNA CTA was significantly associated with the advanced clinical stage and tumor size. In addition, OS patients with low lncRNA CTA levels showed a worse prognosis when compared with those with high expression of lncRNA CTA. Furthermore, we report that lncRNA CTA has an inverse relationship with miR-210 expression in OS tissues. LncRNA CTA could be activated by doxorubicin (DOX), and could promote OS cell apoptosis by competitively binding miR-210, while inhibit cell autophagy. On the other hand, lncRNA CTA was downregulated in DOX-resistant OS cells. Overexpression of lncRNA CTA reduced autophagy and subsequently overcame DOX resistance of OS in vitro and in vivo. Therefore, we demonstrate that lncRNA CTA is an essential regulator in DOX-induced OS cell apoptosis, and the lncRNA CTA-miR-210 axis plays an important role in reducing OS chemoresistance.

MicroRNA-410 regulates autophagy-related gene ATG16L1 expression and enhances chemosensitivity via autophagy inhibition in osteosarcoma

Osteosarcoma, which is the most common type of primary bone tumor in adolescents, is characterized by complex genetic alterations and frequent resistance to conventional treatments. MicroRNAs (miRs) have emerged as fundamental regulators in gene expression through their ability to silence gene expression at post-transcriptional and translational levels. The present study investigated the role of miR-410 in the progression of osteosarcoma. The results demonstrated that the expression of miR-410 was markedly downregulated in human osteosarcoma tissues, and U2OS and MG-63 osteosarcoma cell lines. Clinicopathological significance suggested that miR-410 may be a potential biomarker for chemotherapy-resistant osteosarcoma. Furthermore, overexpression of miR-410 exhibited a limited effect on cell viability in U2OS and MG-63 cells. Target prediction algorithms (TargetScan and miRanda) indicated that autophagy related 16-like 1 (ATG16L1) was a potential target gene of miR-410. A luciferase reporter assay demonstrated that miR-410 directly decreased ATG16L1 expression by targeting its 3′-untranslated region. In addition, the results revealed that miR-410 was able to markedly inhibit autophagy. Accordingly, autophagy was activated as a protective mechanism when osteosarcoma cells were exposed to three common anticancer drugs, including rapamycin, doxorubicin and cisplatin. Furthermore, the autophagy inhibitor 3-methyladenine and miR-410 expression were able to improve the therapeutic response of the cells to chemotherapy drugs (rapamycin, doxorubicin and cisplatin), thus indicating that miR-410 enhanced chemosensitivity through autophagy inhibition in osteosarcoma cells. In conclusion, studies regarding the function of miR-410 on autophagy provided insight into the biological function of miR-410 in osteosarcoma and may offer a promising approach for the treatment of osteosarcoma.

Autophagic homeostasis is required for the pluripotency of cancer stem cells

Pluripotency is an important feature of cancer stem cells (CSCs) that contributes to self-renewal and chemoresistance. The maintenance of pluripotency of CSCs under various pathophysiological conditions requires a complex interaction between various cellular pathways including those involved in homeostasis and energy metabolism. However, the exact mechanisms that maintain the CSC pluripotency remain poorly understood. In this report, using both human and murine models of CSCs, we demonstrate that basal levels of autophagy are required to maintain the pluripotency of CSCs, and that this process is differentially regulated by the rate-limiting enzyme in the NAD⁺ synthesis pathway NAMPT (nicotinamide phosphoribosyltransferase) and the transcription factor POU5F1/OCT4 (POU class 5 homeobox 1). First, our data show that the pharmacological inhibition and knockdown (K_D) of NAMPT or the K_D of POU5F1 in human CSCs significantly decreased the expression of pluripotency markers POU5F1, NANOG (Nanog homeobox) and SOX2 (SRY-box 2), and upregulated the differentiation markers TUBB3 (tubulin β 3 class III), CSN2 (casein β), SPP1 (secreted phosphoprotein 1), GATA6 (GATA binding protein 6), T (T brachyury transcription factor) and CDX2 (caudal type homeobox 2). Interestingly, these pluripotency-regulating effects of NAMPT and POU5F1 were accompanied by contrasting levels of autophagy, wherein NAMPT K_D promoted while POU5F1 K_D inhibited the autophagy machinery. Most importantly, any deviation from the basal level of autophagy, either increase (via rapamycin, serum starvation or Tat-beclin 1 [Tat-BECN1] peptide) or decrease (via ATG7 or ATG12 K_D), strongly decreased the pluripotency and promoted the differentiation and/or senescence of CSCs. Collectively, these results uncover the link between the NAD⁺ biosynthesis pathway, CSC transcription factor POU5F1 and pluripotency, and further identify autophagy as a novel regulator of pluripotency of CSCs.

Doxorubicin impairs cardiomyocyte viability by suppressing transcription factor EB expression and disrupting autophagy

Doxorubicin (DOX) is an effective anti-cancer agent. However, DOX treatment increases patient susceptibility to dilated cardiomyopathy. DOX predisposes cardiomyocytes to insult by suppressing mitochondrial energy metabolism, altering calcium flux, and disrupting proteolysis and proteostasis. Prior studies have assessed the role of macroautophagy in DOX cardiotoxicity; however, limited studies have examined whether DOX mediates cardiac injury through dysfunctions in inter- and/or intra-lysosomal signaling events. Lysosomal signaling and function is governed by transcription factor EB (TFEB). In the present study, we hypothesized that DOX caused myocyte injury by impairing lysosomal function and signaling through negative regulation of TFEB. Indeed, we found that DOX repressed cellular TFEB expression, which was associated with impaired cathepsin proteolytic activity across in vivo, ex vivo, and in vitro models of DOX cardiotoxicity. Furthermore, we observed that loss of TFEB was associated with reduction in macroautophagy protein expression, inhibition of autophagic flux, impairments in lysosomal cathepsin B activity, and activation of cell death. Restoration and/or activation of TFEB in DOX-treated cardiomyocytes prevented DOX-induced suppression of cathepsin B activity, reduced DOX-mediated reactive oxygen species (ROS) overproduction, attenuated activation of caspase-3, and improved cellular viability. Collectively, loss of TFEB inhibits lysosomal autophagy, rendering cardiomyocytes susceptible to DOX-induced proteotoxicity and injury. Our data reveal a novel mechanism wherein DOX primes cardiomyocytes for cell death by depleting cellular TFEB.

Enhanced autophagy in cytarabine arabinoside-resistant U937 leukemia cells and its potential as a target for overcoming resistance

Autophagy is a lysosomal degradation mechanism that is essential for cell survival, differentiation, development, and homeostasis. Autophagy protects cells from various stresses, including protecting normal cells from harmful metabolic conditions, and cancer cells from chemotherapeutics. In the current study, a cytarabine arabinoside (Ara-C)-sensitive U937 leukemia cell line and an Ara-C-resistant U937 (U937/AR) cell line were assessed for baseline autophagy activity by investigating the LC3-I conversion to LC3-II, performing EGFP-LC3 puncta, an acidic autophagolysosome assay, and measuring the expression of various autophagy-related genes. The results demonstrated significantly higher autophagic activity in the U937/AR cells compared with the U937 cells, when the cells were cultured with or without serum. Furthermore, an increase in the autophagic activity in starved U937/AR cells was demonstrated, compared with that in the starved U937 cells. Administration of an autophagy inhibitor demonstrated no change in cell death in the two cell lines when cultured with serum, however, it induced cell death regardless of the Ara-C sensitivity when the cell lines were cultured without serum. In addition, the U937 cells demonstrated an Ara-C resistance when cultured without serum. Co-treatment with Ara-C and the autophagy inhibitor significantly induced cell death in the U937/AR and Ara-C-sensitive U937 cells. In conclusion, autophagy serves an important role in protecting U937 cells from Ara-C and in the development of Ara-C resistance. Inhibition of autophagy combined with the Ara-C treatment in the U937 cells augmented the anti-leukemic effect of Ara-C and overcame Ara-C resistance, suggesting that autophagy may be an important therapeutic target to further improve the treatment outcome in patients with acute myeloid leukemia.

Oncolytic adenovirus‑mediated mda‑7/IL‑24 expression suppresses osteosarcoma growth and enhances sensitivity to doxorubicin

Osteosarcoma (OS) is a malignant disease with a high mortality rate and poor response to current chemotherapy. Melanoma differentiation associated gene‑7 (Mda7)/interleukin (IL)‑24 has been demonstrated to suppress the growth of OS. However, the expression level of Mda7/IL‑24 mediated by the current adenoviral vector is limited for effective clinical treatment of OS. In order to solve this issue, an oncolytic adenovirus was employed to express IL‑24 (OA‑IL‑24) in OS cells. Quantitative polymerase chain reaction, immunoblot and ELISA assays verified that OA‑IL‑24 expressed IL‑24 at a higher level than the replication‑deficient adenoviral vector, Ad‑IL24. OA‑IL‑24 infection led to decreased cell viability and increased apoptosis of OS cells, compared with Ad‑IL‑24. Animal studies further confirmed the increased anti‑tumor activity of OA‑IL‑24. Notably, OA‑IL‑24 was also found to sensitize OS cells to doxorubicin. OA‑IL‑24‑induced multiple drug resistance reversion was associated with reduced expression of Pgp and BCRP1, as well as minimized autophagy. Furthermore, restoring Pgp and BCRP1 expression as well as autophagy, was able to rescue the effect of IL‑24 on the cytotoxicity of doxorubicin to OS. In conclusion, a method for inducing a high expression of IL‑24 in OS was provided. In addition, IL‑24 was demonstrated to increase the sensitivity of OS to doxorubicin.

Autophagy inhibitors as a potential antiamoebic treatment for Acanthamoeba keratitis

Acanthamoeba cysts are resistant to extreme physical and chemical conditions. Autophagy is an essential pathway for encystation of Acanthamoeba cells. To evaluate the possibility of an autophagic Acanthamoeba encystation mechanism, we evaluated autophagy inhibitors, such as 3-methyladenine (3MA), LY294002, wortmannin, bafilomycin A, and chloroquine. Among these autophagy inhibitors, the use of 3MA and chloroquine showed a significant reduction in the encystation ratio in Acanthamoeba cells. Wortmannin also inhibited the formation of mature cysts, while LY294002 and bafilomycin A did not affect the encystation of Acanthamoeba cells. Transmission electron microscopy revealed that 3MA and wortmannin inhibited autophagy formation and that chloroquine interfered with the formation of autolysosomes. Inhibition of autophagy or autolysosome formation resulted in a significant block in the encystation in Acanthamoeba cells. Clinical treatment with 0.02% polyhexamethylene biguanide (PHMB) showed high cytopathic effects on Acanthamoeba trophozoites and cysts; however, it also revealed high cytopathic effects on human corneal epithelial cells. In this study, we investigated effects of the combination of a low (0.00125%) concentration of PHMB with each of the autophagy inhibitors 3MA, wortmannin, and chloroquine on Acanthamoeba and human corneal epithelial cells. These new combination treatments showed low cytopathic effects on human corneal cells and high cytopathic effects on Acanthamoeba cells. Taken together, these results provide fundamental information for optimizing the treatment of Acanthamoeba keratitis.