Autophagy and Apoptosis Play Opposing Roles in Overall Survival of Esophageal Squamous Cell Carcinoma

TAOK3 Facilitates Esophageal Squamous Cell Carcinoma Progression and Cisplatin Resistance Through Augmenting Autophagy Mediated by IRGM

Esophageal squamous cell carcinoma (ESCC) is one of the deadliest cancers because of its robust aggressive phenotype and chemoresistance. TAO kinase belongs to mitogen-activated protein kinases, which mediate drug resistance in multiple cancers. However, the role of TAO kinase in ESCC progression and chemoresistance has never been explored. Here, it is reported that TAOK3 augments cell autophagy and further promotes ESCC progression and chemoresistance. Mechanistically, TAOK3 phosphorylates KMT2C at S4588 and strengthens the interaction between KMT2C and ETV5. Consequently, the nuclear translocation of KMT2C is increased, and the transcription of autophagy-relevant gene IRGM is further upregulated. Additionally, the inhibitor SBI-581 can significantly suppress cell autophagy mediated by TAOK3 and synergizes with cisplatin to treat ESCC in vitro and in vivo.

The role of autophagy in initiation, progression, TME modification, diagnosis, and treatment of esophageal cancers

Autophagy is a highly conserved metabolic process with a cytoprotective function. Autophagy is involved in cancer, infection, immunity, and inflammation and may be a potential therapeutic target. Increasing evidence has revealed that autophagy has primary implications for esophageal cancer, including its initiation, progression, tumor microenvironment (TME) modification, diagnosis, and treatment. Notably, autophagy displayed excellent application potential in radiotherapy combined with immunotherapy. Radiotherapy combined with immunotherapy is a new potential therapeutic strategy for cancers, including esophageal cancer. Autophagy modulators can work as adjuvant enhancers in radiotherapy or immunotherapy of cancers. This review highlights the most recent data related to the role of autophagy regulation in esophageal cancer.

miR-296-5p promotes autophagy in mouse LS8 cells under excessive fluoride via AMPK/ULK1 pathways

Numerous microRNAs participate in regulating the pathological process of autophagy. We have found miR-296-5p is one of the most significantly down-regulated microRNAs in a high concentration of sodium fluoride. However, it is not clear whether miR-296-5p augments autophagy in dental fluorosis. Our purpose is to explore the function of miR-296-5p in regulating autophagy of excessive fluoride development. Thus, the cell line of ameloblasts LS8 was exposed to a 1.5 mM dose of NaF and miR-296-5p-mimics, Real-time qPCR, CCK-8 assays, Fluorescence imaging and Western blot analysis were performed. Autophagy was observed. As our results indicated, miR-296-5p overexpression in mouse LS8 cells significantly accelerated autophagy. The autophagy inhibition effect of miR-296-5p underexpression was consistent with the effect of the AMPK inhibitor. And we found that the expression of LC3II was decreased via down-regulation of AMPK. The change of ULK1 by miR-296-5p may be accomplished through AMPK. Thus, miR-296-5p may improve the secretion of autophagic mediators by activating AMPK/ULK1 expression in fluorosis, suggesting that miR-296-5p, AMPK/ULK1 may be potential therapeutic targets under the higher fluoride stimulation.

Associations of Porphyromonas gingivalis Infection and Low Beclin1 Expression With Clinicopathological Parameters and Survival of Esophageal Squamous Cell Carcinoma Patients

Purpose: The present study focused on exploring the associations of Porphyromonas gingivalis (P. gingivalis) infection and low Beclin1 expression with clinicopathological parameters and survival of esophageal squamous cell carcinoma (ESCC) patients, so as to illustrate its clinical significance and prognostic value. Methods: Immunohistochemistry (IHC) was used to detect P. gingivalis infection status and Beclin1 expression in 370 ESCC patients. The chi-square test was adopted to illustrate the relationship between categorical variables, and Cohen's kappa coefficient was used for correlation analysis. Kaplan-Meier survival curves with the log-rank test were used to analyse the correlation of P. gingivalis infection and low Beclin1 expression with survival time. The effects of P. gingivalis infection and Beclin1 downregulation on the proliferation, migration and antiapoptotic abilities of ESCC cells in vitro were detected by Cell Counting Kit-8, wound healing and flow cytometry assays. For P. gingivalis infection of ESCC cells, cell culture medium was replaced with antibiotic-free medium when the density of ESCC cells was 70-80%, cells were inoculated with P. gingivalis at a multiplicity of infection (MOI) of 10. Result: P. gingivalis infection was negatively correlated with Beclin1 expression in ESCC tissues, and P. gingivalis infection and low Beclin1 expression were associated with differentiation status, tumor invasion depth, lymph node metastasis, clinical stage and prognosis in ESCC patients. In vitro experiments confirmed that P. gingivalis infection and Beclin1 downregulation potentiate the proliferation, migration and antiapoptotic abilities of ESCC cells (KYSE150 and KYSE30). Our results provide evidence that P. gingivalis infection and low Beclin1 expression were associated with the development and progression of ESCC. Conclusion: Long-term smoking and alcohol consumption causes poor oral and esophageal microenvironments and ESCC patients with these features were more susceptible to P. gingivalis infection and persistent colonization, and exhibited lower Beclin1 expression, worse prognosis and more advanced clinicopathological features. Our findings indicate that effectively eliminating P. gingivalis colonization and restoring Beclin1 expression in ESCC patients may contribute to preventation and targeted treatment, and yield new insights into the aetiological research on ESCC.

Bioinformatics Analysis of Autophagy-related lncRNAs in Esophageal Carcinoma

BACKGROUND

Esophageal carcinoma (ESCA) is a malignant tumor with high invasiveness and mortality. Autophagy has multiple roles in the development of cancer; however, there are limited data on autophagy genes associated with long non-coding RNAs (lncRNAs) in ESCA. The purpose of this study was to screen potential diagnostic and prognostic molecules and to identify gene co-expression networks associated with autophagy in ESCA.

METHODS

We downloaded transcriptome expression profiles from The Cancer Genome Atlas and autophagy-related gene data from the Human Autophagy Database and analyzed the co-expression of mRNAs and lncRNAs. In addition, the diagnostic and prognostic value of autophagy-related lncRNAs was analyzed by multivariate Cox regression. Furthermore, Kyoto Encyclopedia of Genes and Genomes analysis was carried out for high-risk patients, and enriched pathways were analyzed by gene set enrichment analysis.

RESULTS

The results showed that genes of high-risk patients were enriched in protein export and spliceosome. Based on Cox stepwise regression and survival analysis, we identified seven autophagy-related lncRNAs with prognostic and diagnostic value, with the potential to be used as a combination to predict the prognosis of patients with ESCA. Finally, a co-expression network related to autophagy was constructed.

CONCLUSION

These results suggest that autophagy-related lncRNAs and the spliceosome play important parts in the pathogenesis of ESCA. Our findings provide new insight into the molecular mechanism of ESCA and suggest a new method for improving its treatment.

The role of non-apoptotic cell death in the treatment and drug-resistance of digestive tumors

Tumor cell apoptosis evasion is one of the main reasons for easy metastasis occurrence, chemotherapy resistance, and the low five-year survival rate of digestive system tumors. Current research has shown that non-apoptotic cell death plays an important role in tumors of the digestive system. Therefore, increasing the proportion of non-apoptotic tumor cells is one of the effective methods of improving therapeutic efficacies for digestive system tumors. Non-apoptotic cell death modes mainly include autophagic cell death, pyroptosis, ferroptosis, in addition to other cell death modes. This review covers a systematic review relating to the research progress made into autophagic cell death, pyroptosis, ferroptosis, and other cell death modes in the treatment of digestive system tumors. It also highlights how treatment is a reasonable prospect based on clinical experience and provides reliable guidance for the further development of digestive system tumor treatments.

Autophagy-Related Beclin 1 and Head and Neck Cancers

Beclin 1, a positive regulator of autophagy, behaves as a double-edged sword in tumorigenesis. Beclin 1 contributes to tumor suppression by removing defective or damaged organelles and other cellular components; however, its activity can also stimulate cancer initiation and progression. In head and neck cancer, Beclin 1 overexpression promotes autophagy, which limits DNA damage and chromosomal instability and increases necrosis and inflammation by impacting apoptotic and autophagic pathways. This paper reviews the relationship between Beclin 1, carcinogenesis and head and neck cancer prognosis.

Roles for Autophagy in Esophageal Carcinogenesis: Implications for Improving Patient Outcomes

Esophageal cancer is among the most aggressive forms of human malignancy with five-year survival rates of <20%. Autophagy is an evolutionarily conserved catabolic process that degrades and recycles damaged organelles and misfolded proteins to maintain cellular homeostasis. While alterations in autophagy have been associated with carcinogenesis across tissues, cell type- and context-dependent roles for autophagy have been reported. Herein, we review the current knowledge related to autophagy in esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC), the two most common subtypes of esophageal malignancy. We explore roles for autophagy in the development and progression of ESCC and EAC. We then continue to discuss molecular markers of autophagy as they relate to esophageal patient outcomes. Finally, we summarize current literature examining roles for autophagy in ESCC and EAC response to therapy and discuss considerations for the potential use of autophagy inhibitors as experimental therapeutics that may improve patient outcomes in esophageal cancer.

Enhancing autophagy protects platelets in immune thrombocytopenia patients

Background

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder and involves increased apoptosis of platelets. Autophagy is an essential process for platelets to maintain their life and physiological functions. However, the role of autophagy in ITP platelets was previously unclear.

Methods

In the present study, the expression of autophagy-related protein and autophagy flux were detected in platelets from ITP patients and healthy controls by immunofluorescence staining and immunoblotting, and the influence of autophagy on the viability and apoptosis of ITP platelets was further explored.

Results

We found that platelet autophagy was diminished in ITP patients. Platelet autophagy in ITP was regulated by the PI3K/AKT/mTOR pathway, with mTOR (mammalian target of rapamycin) as a negative regulator and class III PtdIns3K playing a crucial role in the process. Importantly, the small-molecule compound ABO (6-amino-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine) enhanced autophagy in ITP platelets. Enhancing platelet autophagy alleviated platelet destruction by inhibiting apoptosis and improving platelet viability.

Conclusions

These results suggest a role for autophagy regulation in the pathogenesis of ITP, and offer a novel treatment for these patients.

Differences in LC3B expression and prognostic implications in oropharyngeal and oral cavity squamous cell carcinoma patients

Background

This study examined the prognostic significance of microtubule-associated protein light chain 3B (LC3B) expression in oropharyngeal and oral cavity squamous cell carcinoma (SCC). The prognostic significance of LC3B expression in relation to human papillomavirus (HPV) status in oropharyngeal SCC was also examined.

Methods

Tissue microarrays (TMAs) were constructed from formalin-fixed, paraffin-embedded oropharyngeal (n = 47) and oral cavity (n = 95) SCC tissue blocks from patients with long-term recurrence and overall survival data (median = 47 months). LC3B expression on tumour was assessed by immunohistochemistry and evaluated for associations with clinicopathological variables. LC3B expression was stratified into high and low expression cohorts using ROC curves with Manhattan distance minimisation, followed by Kaplan–Meier and multivariable survival analyses. Interaction terms between HPV status and LC3B expression in oropharyngeal SCC patients were also examined by joint-effects and stratified analyses.

Results

Kaplan–Meier survival and univariate analyses revealed that high LC3B expression was correlated with poor overall survival in oropharyngeal SCC patients (p = 0.007 and HR = 3.18, 95% CI 1.31–7.71, p = 0.01 respectively). High LC3B expression was also an independent prognostic factor for poor overall survival in oropharyngeal SCC patients (HR = 4.02, 95% CI 1.38–11.47, p = 0.011). In contrast, in oral cavity SCC, only disease-free survival remained statistically significant after univariate analysis (HR = 2.36, 95% CI 1.19–4.67, p = 0.014), although Kaplan-Meier survival analysis showed that high LC3B expression correlated with poor overall and disease-free survival (p = 0.046 and 0.011 respectively). Furthermore, oropharyngeal SCC patients with HPV-negative/high LC3B expression were correlated with poor overall survival in both joint-effects and stratified presentations (p = 0.024 and 0.032 respectively).

Conclusions

High LC3B expression correlates with poor prognosis in oropharyngeal and oral cavity SCC, which highlights the importance of autophagy in these malignancies. High LC3B expression appears to be an independent prognostic marker for oropharyngeal SCC but not for oral cavity SCC patients. The difference in the prognostic significance of LC3B between oropharyngeal and oral cavity SCCs further supports the biological differences between these malignancies. The possibility that oropharyngeal SCC patients with negative HPV status and high LC3B expression were at particular risk of a poor outcome warrants further investigation in prospective studies with larger numbers.

Autophagy as a cytoprotective mechanism in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is amongst the most aggressive human malignancies, representing a significant health burden worldwide. Autophagy is an evolutionarily conserved catabolic process that degrades and recycles damaged organelles and misfolded proteins to maintain cellular homeostasis. Alterations in autophagy are associated with cancer pathogenesis, including ESCC; however, the functional role of autophagy in ESCC remains elusive. Here, we discuss the clinical relevance of autophagy effectors in ESCC and review current knowledge regarding the molecular mechanisms through which autophagy contributes to ESCC. We highlight the cytoprotective role of autophagy in ESCC and discuss autophagy inhibitors as novel experimental therapeutics to potentiate the effects of anti-cancer therapies and/or to overcome therapeutic resistance in ESCC.

miR-503 suppresses the proliferation and metastasis of esophageal squamous cell carcinoma by triggering autophagy via PKA/mTOR signaling

MicroRNA (miR)-503 is involved in the regulation of the malignant phenotype in multiple tumor types, and has been proven to be a novel diagnostic and therapeutic target; however, its function and mechanisms of action have not yet been fully elucidated in esophageal squamous cell carcinoma (ESCC). In the current study, we detected miR‑503 expression by RT‑qPCR and found that miR‑503 expression was increased in ESCC, but negatively correlated with lymph node metastasis, TNM stage and tumor differentiation. Functionally, we confirmed that miR‑503 inhibited the proliferation and metastasis of ESCC cells by triggering cellular autophagy. Mechanistically, we confirmed that miR‑503 exerted its biological effects by targeting protein kinase CAMP‑activated catalytic subunit alpha (PRKACA) in ESCC by dual luciferase reporter assay. Moreover, miR‑503 was found to trigger autophagy in ESCC cells through the protein kinase A (PKA)/mammalian target of rapamycin (mTOR) pathway. Taken together, our results demonstrate that miR‑503 suppresses the proliferation and metastasis of ESCC via the activation of autophagy, mediated by the PKA/mTOR signaling pathway.

Ceramide activates lysosomal cathepsin B and cathepsin D to attenuate autophagy and induces ER stress to suppress myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) are immune suppressive cells that are hallmarks of human cancer. MDSCs inhibit cytotoxic T lymphocytes (CTLs) and NK cell functions to promote tumor immune escape and progression, and therefore are considered key targets in cancer immunotherapy. Recent studies determined a key role of the apoptosis pathways in tumor-induced MDSC homeostasis and it is known that ceramide plays a key role in regulation of mammalian cell apoptosis. In this study, we aimed to determine the efficacy and underlying molecular mechanism of ceramide in suppression of MDSCs. Treatment of tumor-bearing mice with LCL521, a lysosomotropic inhibitor of acid ceramidase, significantly decreased MDSC accumulation in vivo. Using a MDSC-like myeloid cell model, we determined that LCL521 targets lysosomes and increases total cellular C16 ceramide level. Although MDSC-like cells have functional apoptosis pathways, LCL521-induced MDSC death occurs in an apoptosis- and necroptosis-independent mechanism. LCL521 treatment resulted in an increase in the number of autophagic vesicles, heterolysosomes and swollen ERs. Finally, concomitant inhibition of cathepsin B and cathepsin D was required to significantly decrease LCL521-induced cell death. Our observations indicate that LCL521 targets lysosomes to activate cathepsin B and cathepsin D, resulting in interrupted autophagy and ER stress that culminates in MDSC death. Therefore, a ceramidase inhibitor is potentially an effective adjunct therapeutic agent for suppression of MDSCs to enhance the efficacy of CTL-based cancer immunotherapy.