Map1lc3b and Sqstm1 Modulated Autophagy for Tumorigenesis and Prognosis in Certain Subsites of Oral Squamous Cell Carcinoma

Role of circRNAs in regulating cell death in cancer: a comprehensive review

Despite multiple diagnostic and therapeutic advances, including surgery, radiation therapy, and chemotherapy, cancer preserved its spot as a global health concern. Prompt cancer diagnosis, treatment, and prognosis depend on the discovery of new biomarkers and therapeutic strategies. Circular RNAs (circRNAs) are considered as a stable, conserved, abundant, and varied group of RNA molecules that perform multiple roles such as gene regulation. There is evidence that circRNAs interact with RNA-binding proteins, especially capturing miRNAs. An extensive amount of research has presented the substantial contribution of circRNAs in various types of cancer. To fully understand the linkage between circRNAs and cancer growth as a consequence of various cell death processes, including autophagy, ferroptosis, and apoptosis, more research is necessary. The expression of circRNAs could be controlled to limit the occurrence and growth of cancer, providing a more encouraging method of cancer treatment. Consequently, it is critical to understand how circRNAs affect various forms of cancer cell death and evaluate whether circRNAs could be used as targets to induce tumor death and increase the efficacy of chemotherapy. The current study aims to review and comprehend the effects that circular RNAs exert on cell apoptosis, autophagy, and ferroptosis in cancer to investigate potential cancer treatment targets.

Prediction significance of autophagy-related genes in survival probability and drug resistance in diffuse large B-cell lymphoma

BACKGROUND/AIMS

Diffuse large B-cell lymphoma (DLBCL), the most common subtype of non-Hodgkin lymphoma, has significant prognostic heterogeneity. This study aimed to generate a prognostic prediction model based on autophagy-related genes for DLBCL patients.

METHODS

Utilizing bioinformatics techniques, we analyzed the clinical information and transcriptome data of DLBCL patients from the Gene Expression Omnibus (GEO) database. Through unsupervised clustering, we identified new autophagy-related molecular subtypes and pinpointed differentially expressed genes (DEGs) between these subtypes. Based on these DEGs, a prognostic model was constructed using Cox and Lasso regression. The effectiveness, accuracy, and clinical utility of this prognostic model were assessed using numerous independent validation cohorts, survival analyses, receiver operating characteristic (ROC) curves, multivariate Cox regression analysis, nomograms, and calibration curves. Moreover, functional analysis, immune cell infiltration, and drug sensitivity analysis were performed.

RESULTS

DLBCL patients with different clinical characterizations (age, molecular subtypes, ECOG scores, and stages) showed different expression features of autophagy-related genes. The prediction model was constructed based on the eight autophagy-related genes (ADD3, IGFBP3, TPM1, LYZ, AFDN, DNAJC10, GLIS3, and CCDC102A). The prognostic nomogram for overall survival of DLBCL patients incorporated risk level, stage, ECOG scores, and molecular subtypes, showing excellent agreement between observed and predicted outcomes. Differences were noted in the proportions of immune cells (native B cells, Treg cells, CD8+ T cell, CD4+ memory activated T cells, gamma delta T cells, macrophages M1, and resting mast cells) between high-risk and low-risk groups. LYZ and ADD3 exhibited correlations with drug resistance to most chemotherapeutic drugs.

CONCLUSIONS

This study established a novel prognostic assessment model based on the expression profile of autophagy-related genes and clinical characteristics of DLBCL patients, explored immune infiltration and predicted drug resistance, which may guide precise and individualized immunochemotherapy regimens.

Mitophagy-related genes could facilitate the development of septic shock during immune infiltration

Septic shock often occurs following critically low blood pressure in patients with sepsis, and is accompanied by a high death rate. Although mitophagy is associated with infection and immune responses, its role in septic shock remains unknown. This study screened effective mitophagy-related genes (MRGs) for medical practice and depicted immune infiltration situations in patients with septic shock. Gene expression profiles of GSE131761 from the Gene Expression Omnibus database were compiled for differential analysis, weighted gene co-expression network analysis, and immune infiltration analysis, while other GSE series were used as validation datasets. A series of validation methods were used to verify the robustness of hub genes, while a nomogram and prognosis model were established for medical practice. Six genes were screened via combinations of differentially expressed genes, weighted gene co-expression network analysis, and MRGs. From this, 3 hub genes (MAP1LC3B, ULK1, and CDC37) were chosen for subsequent analysis based on different validation methods. Gene set enrichment analysis showed that leukocyte trans-endothelial migration and the p53 signaling pathway were abnormally activated during septic shock. Immune infiltration analysis indicated that the imbalance of neutrophils and CD4 naive T cells was significantly correlated with septic shock progression. A nomogram was generated based on MAP1LC3B, ULK1, and CDC37, as well as age. The stability of our model was confirmed using a calibration plot. Importantly, patients with septic shock with the 3 highly expressed hub genes displayed worse prognosis than did patients without septic shock. MAP1LC3B, ULK1, and CDC37 are considered hub MRGs in the development of septic shock and could represent promising diagnostic and prognostic biomarkers in blood tissue. The validated hub genes and immune infiltration pattern expand our knowledge on MRG functional mechanisms, which provides guidance and direction for the development of septic shock diagnostic and therapeutic markers.

MAP3K11 facilitates autophagy activity and is correlated with malignancy of oral squamous cell carcinoma

Autophagy-related 4B (ATG4B) is a protease required for core machinery of autophagy. Phosphorylation of ATG4B promotes autophagy and is correlated with poor outcome of cancer. However, little is known about the upstream kinases for ATG4B phosphorylation and their association with clinical outcomes of cancer patients. Through siRNA library screening, MAP3K11 was identified as a potential kinase that phosphorylates ATG4B and increases its proteolytic activity. Ablation of MAP3K11 attenuated pS383/392-ATG4B protein levels and autophagic flux in oral cancer cells. Moreover, loss of MAP3K11 inhibited oral cancer cell growth, migration/invasion, and synergized starvation-reduced cell viability. MAP3K11 knock-out cancer cells also showed growth inhibition in vivo. Furthermore, the protein level of MAP3K11 was higher in tumor tissues than that in adjacent normal tissues in patients with oral squamous cell carcinoma (OSCC), comprising 179 buccal mucosa squamous cell carcinoma (BMSCC) and 249 tongue squamous cell carcinoma (TSCC). MAP3K11 protein levels were positively correlated with ATG4B and pS383/392-ATG4B levels in patients with OSCC, particularly in TSCC. In addition, high coexpression of MAP3K11 and ATG4B was associated with poor disease-specific survival in BMSCC and TSCC, while high coexpression of MAP3K11 and pS383/392-ATG4B was associated with unfavorable disease-free survival in BMSCC and TSCC. Taken together, our results indicated that MAP3K11 stimulated activity of ATG4B and autophagy, which may confer to malignancy of cancer cells. The expression of MAP3K11 and ATG4B was further associated with poor survival of OSCC, suggesting MAP3K11 could serve as a theranostic target of patients with OSCC.

Non-Coding RNAs and Oral Cancer: Small Molecules With Big Functions

Oral cancer remains a major public concern with considerable socioeconomic impact in the world. Despite substantial advancements have been made in treating oral cancer, the five-year survival rate for oral cancer remained undesirable, and the molecular mechanisms underlying OSCC carcinogenesis have not been fully understood. Noncoding RNAs (ncRNAs) include transfer RNAs (tRNAs), as well as small RNAs such as microRNAs, and the long ncRNAs such as HOTAIR are a large segment of the transcriptome that do not have apparent protein-coding roles, but they have been verified to play important roles in diverse biological processes, including cancer cell development. Cell death, such as apoptosis, necrosis, and autophagy, plays a vital role in the progression of cancer. A better understanding of the regulatory relationships between ncRNAs and these various types of cancer cell death is therefore urgently required. The occurrence and development of oral cancer can be controlled by increasing or decreasing the expression of ncRNAs, a method which confers broad prospects for oral cancer treatment. Therefore, it is urgent for us to understand the influence of ncRNAs on the development of different modes of oral tumor death, and to evaluate whether ncRNAs have the potential to be used as biological targets for inducing cell death and recurrence of chemotherapy. The purpose of this review is to describe the impact of ncRNAs on cell apoptosis and autophagy in oral cancer in order to explore potential targets for oral cancer therapy.

Kinome-Wide siRNA Screening Identifies DYRK1B as a Potential Therapeutic Target for Triple-Negative Breast Cancer Cells

Simple Summary

Therapeutic target is limited for patients with triple-negative breast cancer (TNBC). Through kinome-wide siRNA (709 genes) screening, DYRK1B was identified as a potential gene essential for cell proliferation and mobility of TNBC cells, particularly in DYRK1B highly expressed TNBC cells. TNBC patients with high expression of DYRK1B had poor overall survival and disease-free survival. CCDC97 and ZNF581 were positively correlated with DYRK1B expression and might be involved in DYRK1B-mediated tumor malignancy in TNBC patients, providing DYRK1B as a potential theranostic target for TNBC.

Abstract

Aims: The selective molecules for targeted therapy of triple-negative breast cancer (TNBC) are limited. Several kinases play pivotal roles in cancer development and malignancy. The study aims to determine if any kinases confer to malignancy of TNBC cells, which could serve as a theranostic target for TNBC. Methods: Kinome siRNA library was used to screen selective genes required for the proliferation of TNBC cells. The involvement of DYRK1B in cancer malignancy was evaluated with migration, invasion assays, and spheroid culture. The expression of DYRK1B was confirmed with quantitative PCR and immunoblotting. The clinical correlation of DYRK1B in TNBC patients was examined with tissue microarray and The Cancer Genome Atlas (TCGA) database. Results: Our results showed that silencing DYRK1B significantly suppressed cell viability in DYRK1B-high expressed TNBC cells, likely by arresting the cell cycle at the G₁ phase. Nevertheless, silencing DYRK1B had marginal effects on DYRK1B-low expressed TNBC cells. Similarly, the knockdown of DYRK1B decreased tumorsphere formation and increased cell death of the tumorsphere. Moreover, inactivation of DYRK1B by either specific inhibitor or ectopic expressing catalytic mutant of DYRK1B inhibited cell viability and metastatic characteristics, including migration and invasion. In addition, DYRK1B protein expression was elevated in tumor tissues compared to that in adjacent normal tissues of TNBC patients. Further, DYRK1B gene expression was highly correlated with CCDC97 or ZNF581 genes in TNBC cells and patients. High co-expression of DYRK1B with CCDC97 or ZNF581 was significantly associated with unfavorable overall survival and disease-free survival of TNBC patients. Conclusions: our results suggest DYRK1B might be essential for promoting tumor progression and could be a theranostic target for TNBC. Silencing or inactivation of DYRK1B might be a potential targeted therapy for TNBC.

Effect of EGFR on SQSTM1 Expression in Malignancy and Tumor Progression of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common types of malignant tumor. Sequestosome 1 (SQSTM1) serves as an adaptor of autophagy for degrading protein aggregates. The regulation of autophagy by EGFR and its clinical impacts are indicated in various types of cancer. However, the association of EGFR and SQSTM1 in OSCC is still unknown. Our results show that the expression levels of SQSTM1 and EGFR proteins are higher in tumor tissues than in the corresponding tumor-adjacent (CTAN) tissues of OSCC patients. The expression levels of SQSTM1 were positively associated with the EGFR expression level. High co-expression of SQSTM1 and EGFR is associated with poor prognosis in OSCC patients. Moreover, SQSTM1 expression is decreased in EGFR-knockdown cells. Cell growth and invasion/migration are also decreased in cells with single/combined knockdowns of EGFR and SQSTM1 or in SQSTM1-knockdown cells without EGFR kinase inhibitor Lapatinib treatment compared to that in scrambled cells. However, cell growth and invasion/metastasis were not significantly different between the scrambled cells and SQSTM1-knockdown cells in the presence of Lapatinib. This study is the first to indicate the biological roles and clinical significance of SQSTM1 regulation by EGFR in OSCC.

Combined Evaluation of MAP1LC3B and SQSTM1 for Biological and Clinical Significance in Ductal Carcinoma of Breast Cancer

Breast cancer is the leading cause of cancer death in women worldwide. The microtubule-associated protein light chain 3B (MAP1LC3B) and adaptor sequestosome 1 (SQSTM1) are two major markers for autophagy. Increased protein levels of MAP1LC3B and SQSTM1 are considered to be causes of autophagy inhibition or activation in various types of cancers. However, the roles of MAP1LC3B and SQSTM1 in breast cancer are still not clear. Using a tissue microarray from 274 breast invasive ductal carcinoma (IDC) patients, we found that tumor tissues showed higher protein levels of MAP1LC3B and cytoplasmic SQSTM1 in comparison to those in adjacent normal tissues. Moreover, high levels of MAP1LC3B were associated with better survival, including disease-specific survival and disease-free survival (DFS) in IDC patients. Furthermore, high co-expression of MAP1LC3B and SQSTM1 was significantly associated with better DFS in IDC patients. Astonishingly, the autophagy inhibitor accumulated the protein levels of MAP1LC3B/SQSTM1 and enhanced the cytotoxic effects of cisplatin and paclitaxel in MCF7 and BT474 breast cancer cell lines, implying that autophagy inhibition might result in poor prognosis and chemosensitivity in IDC. Taken together, high co-expression of MAP1LC3B and SQSTM1 might serve as a potential diagnostic and prognostic biomarker for IDC patients.

Clinical Significance and the Role of Guanylate-Binding Protein 5 in Oral Squamous Cell Carcinoma

Guanylate binding protein 5 (GBP5) is the interferon (IFN)-inducible subfamily of guanosine triphosphatases (GTPases) and is involved in pathogen defense. However, the role played by GBP5 in cancer development, especially in oral squamous cell carcinoma (OSCC), is still unknown. Herein, next-generation sequencing analysis showed that the gene expression levels of GBP5 were significantly higher in OSCC tissues compared with those found in corresponding tumor adjacent normal tissues (CTAN) from two pairs of OSCC patients. Higher gene expression levels of GBP5 were also found in tumor tissues of 23 buccal mucosal squamous cell carcinoma (BMSCC)/14 tongue squamous cell carcinoma (TSCC) patients and 30 oral cancer patients from The Cancer Genome Atlas (TCGA) database compared with those in CTAN tissues. Immunohistochemical results showed that protein expression levels of GBP5 were also higher in the tumor tissues of 353 OSCC patients including 117 BMSCC, 187 TSCC, and 49 lip squamous cell carcinoma patients. Moreover, TCGA database analysis indicated that high gene expression levels of GBP5 were associated with poor overall survival in oral cancer patients with moderate/poor cell differentiation, and associated with poor disease-free survival in oral cancer patients with moderate/poor cell differentiation and lymph node metastasis. Furthermore, GBP5-knockdowned cells exhibited decreased cell growth, arrest at G1 phase, and decreased invasion/migration. The gene expression of markers for epithelial-mesenchymal transition and cancer stemness was also reduced in GBP5-silenced oral cancer cells. Taken together, GBP5 might be a potential biomarker and therapeutic target for OSCC patients, especially for those with poor cell differentiation and lymph node metastasis.

Tribulus terrestris fruit extract inhibits autophagic flux to diminish cell proliferation and metastatic characteristics of oral cancer cells

Elevated autophagy is highly associated with cancer development and progression. Fruit extracts of several plants inhibit activity of autophagy-related protease ATG4B and autophagy activity in colorectal cancer cells. However, the effects of these plant extracts in oral cancer cells remain unclear. In this study, we found that the extracted Tribulus terrestris fruit (TT-(fr)) and Xanthium strumarium fruit had inhibitory effects on autophagy inhibition in both SAS and TW2.6 oral cancer cells. Moreover, the fruit extracts had differential effects on cell proliferation of oral cancer cells. In addition, the fruit extracts hampered cell migration and invasion of oral cancer cells, particularly in TT-(fr) extracts. Our results indicated that TT-(fr) extracts consistently inhibited autophagic flux, cell growth and metastatic characteristics of oral cancer cells, suggesting TT-(fr) might contain function ingredient to suppress oral cancer cells.

Screening and identification of autophagy-related biomarkers for oral squamous cell carcinoma (OSCC) via integrated bioinformatics analysis

Increasing evidences have showed that autophagy played a significant role in oral squamous cell carcinoma (OSCC). Purpose of our study was to explore the prognostic value of autophagy-related genes (ATGs) and screen autophagy-related biomarkers for OSCC. RNA-seq and clinical data were downloaded from The Cancer Genome Atlas (TCGA) database following extracting ATG expression profiles. Then, differentially expressed analysis was performed in R software and a risk score model according to ATGs was established. Moreover, comprehensive bioinformatics analyses were used to screen autophagy-related biomarkers which were later verified in OSCC tissues and cell lines. A total of 232 ATGs were extracted, and 37 genes were differentially expressed in OSCC. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that these genes were mainly located in autophagosome membrane and associated with autophagy. Furthermore, the risk score on basis of ATGs was identified as potential independent prognostic biomarker. Moreover, ATG12 and BID were identified as potential autophagy-related biomarkers of OSCC. This study successfully constructed a risk model, and the risk score could predict the prognosis of OSCC patients accurately. Moreover, ATG12 and BID were identified as two potential independent prognostic autophagy-related biomarkers and might provide new OSCC therapeutic targets.

Tumor Susceptibility Gene 101 facilitates rapamycin-induced autophagic flux in neuron cells

Tumor Susceptibility Gene 101 (TSG101) is a member of endosomal sorting complexes responsible for endocytic pathway, which is associated with autophagic process. However, the role of TSG101 in autophagy remains unclear. To investigate the effect of TSG101 on the membrane-bound MAP1LC3-II, p62 and ubiquitinated protein levels in neuron cells, immunoblotting was used to evaluate the effects in cells silenced with siRNA against TSG101 and treated with autophagy inducer rapamycin. GFP-MAP1LC3 and tandem fluorescent-tagged LC3 (mTagRFP-mWasabi-MAP1LC3) reporter vectors were used to monitor autophagy in cells using confocal microcopy. The autophagic vacuoles were further validated with transmission electron microscopy. Our results showed that TSG101 expression was slightly increased in neuron cells when exposed to rapamycin. Depletion of TSG101 with siRNA lead to accumulation of MAP1LC3-II, GFP-MAP1LC3 puncta and autophagic vacuoles in the cells. Rapamycin-elevated MAP1LC3-II turnover and RFP⁺Wasabi^- puncta were repressed in TSG101 silenced cells, indicating that TSG101 is involved in rapamycin-induced autophagic flux in cells. Moreover, silencing TSG101 reduced colocalization of Rab7, MAP1LC3 and cell viability, increased p62, ubiquitinated proteins in the neuron cells. Taken together, our results suggested that TSG101 might be required for amphisome formation to promote autophagic flux in neuron cells when exposed to rapamycin.

Regulatory effects of noncoding RNAs on the interplay of oxidative stress and autophagy in cancer malignancy and therapy

Noncoding RNAs (ncRNAs) regulation of various diseases including cancer has been extensively studied. Reactive oxidative species (ROS) elevated by oxidative stress are associated with cancer progression and drug resistance, while autophagy serves as an ROS scavenger in cancer cells. However, the regulatory effects of ncRNAs on autophagy and ROS in various cancer cells remains complex. Here, we explore how currently investigated ncRNAs, mainly miRNAs and lncRNAs, are involved in ROS production through modulating antioxidant genes. The regulatory effects of miRNAs and lncRNAs on autophagy-related (ATG) proteins to control autophagy activity in cancer cells are discussed. Moreover, differential expression of ncRNAs in tumor and normal tissues of cancer patients are further analyzed using The Cancer Genome Atlas (TCGA) database. This review hypothesizes links between ATG genes- or antioxidant genes-modulated ncRNAs and ROS production, which might result in tumorigenesis, malignancy, and cancer recurrence. A better understanding of the regulation of ROS and autophagy by ncRNAs might advance the use of ncRNAs as diagnostic and prognostic markers as well as therapeutic targets in cancer therapy.

Autophagy-Related Signature for Head and Neck Squamous Cell Carcinoma

Background

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies in the world, with low survival and poor quality of life. Autophagy-associated genes (ATGs) have been reported to be involved in the initiation and progression of malignancies. Here, we aimed to investigate the association between autophagy-associated genes and the outcomes in HNSCC patients.

Methods

We obtained ATGs with prognostic values by analyzing the datasets from The Cancer Genome Atlas (TCGA) and Human Autophagy Database (HADb). The enrichment functions of autophagy differential genes were analyzed by Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). The Kaplan-Meier method was applied to the survival curve analysis. A prognostic autophagy-related gene signature was established, and its independence was verified.

Results

We acquired a total of 529 samples and 232 ATGs; further, we identified 45 genes associated with prognosis and built a prognosis autophagy signature based on risk score of 15 genes. Patients were divided into two groups based on risk scores. The Kaplan-Meier curve illustrated that the survival rate of the high-risk group was significantly lower than that of the low-risk group in both the training group and validation group. The ROC curve revealed that the risk score had the highest AUC value in the 3rd and 5th years, reaching 0.703 and 0.724, which are higher than other risk factors such as gender, age, and TNM stage. The nomogram further confirmed its weight in the prognosis of HNSCC patients. Through KEGG and GO enrichment analyses, we observed that ATGs were involved in the tumorigenesis and invasion of tumor by various mediating pathways. We gained 3 hub genes (MAP1LC3B, FADD, and LAMP1) and further analyzed the survival curves, mutations, differential expressions, and their roles in tumors on the online websites.

Conclusion

We identified a novel autophagy-related signature that may provide promising biomarker genes for the treatment and prognosis of HNSCC. We need to validate its prognostic value by applying it to the clinic.

Development and Validation of Autophagy-Related Gene Signature and Nomogram for Predicting Survival in Oral Squamous Cell Carcinoma

Background

Autophagy, a highly conserved self-digesting process, has been deeply involved in the development and progression of oral squamous cell carcinoma (OSCC). However, the prognostic value of autophagy-related genes (ARGs) for OSCC still remains unclear. Our study set out to develop a multigene expression signature based on ARGs for individualized prognosis assessment in OSCC patients.

Methods

Based on The Cancer Genome Atlas (TCGA) database, we identified prognosis-related ARGs through univariate COX regression analysis. Then we performed the least absolute shrinkage and selection operator (LASSO) regression analysis to identify an optimal autophagy-related multigene signature with the subsequent validation in testing set, GSE41613 and GSE42743 datasets.

Results

We identified 36 prognosis-related ARGs for OSCC. Subsequently, the multigene signature based on 13 prognostic ARGs was constructed and successfully divided OSCC patients into low and high-risk groups with significantly different overall survival in TCGA training set (p < 0.0001). The autophagy signature remained as an independent prognostic factor for OSCC in univariate and multivariate Cox regression analyses. The area under the curve (AUC) values of the receiver operating characteristic (ROC) curves for 1, 3, and 5-year survival were 0.758, 0.810, 0.798, respectively. Then the gene signature was validated in TCGA testing set, GSE41613 and GSE42743 datasets. Moreover, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and single-sample gene set enrichment analysis (ssGSEA) revealed the underlying biological characteristics and signaling pathways associated with this signature in OSCC. Finally, we constructed a nomogram by combining the gene signature with multiple clinical parameters (age, gender, TNM-stage, tobacco, and alcohol history). The concordance index (C-index) and calibration plots demonstrated favorable predictive performance of our nomogram.

Conclusion

In summary, we identified and verified a 13-ARGs prognostic signature and nomogram, which provide individualized prognosis evaluation and show insight for potential therapeutic targets for OSCC.

The identification of autophagy-related genes in the prognosis of oral squamous cell carcinoma

OBJECTIVES

The aim of this study was to identify prognostic autophagy-related genes and assess the ability of these genes to predict clinical outcomes in oral squamous cell carcinoma (OSCC).

SUBJECTS AND METHODS

The details of the human autophagy-related genes were obtained from the Human Autophagy Database. The Cancer Genome Atlas database was used to obtain the gene expression profiles and clinical data of patients. Prediction of biological functions of differentially expressed genes was performed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Prognosis-related genes were identified by Cox regression analysis, and the coefficient was applied to construct a prognostic risk score model. The median of the risk score was applied to distinguish between high- and low-risk groups. The Gene Expression Omnibus database, qRT-PCR and immunohistochemistry were used to validate the expression of key genes.

RESULTS

KEGG analyses revealed that differentially expressed genes were mainly enriched in autophagy-related pathways and virus infection. BAK1, BID, NKX2-3 and SPHK1 were identified. The risk score model showed that the high-risk score had poorer overall survival (Kaplan-Meier analysis, p = 1.79 × 10^-7 ). SPHK1 was upregulated in OSCC tissues and cells, and NXK2-3 was downregulated.

CONCLUSIONS

Autophagy-related gene expression profiles may be a potential biomarker for OSCC prognosis.

Caffeic acid phenethyl ester against cadmium induced toxicity mediated by CircRNA modulates autophagy in HepG2 cells

Cadmium pollution and poisoning are serious environmental and pharmacological concerns, and effective drugs can alleviate or offset cadmium-induced toxicity are badly needed. In this study, Caffeic acid phenethyl ester (CAPE), a major active component of propolis, showed protective effect against CdCl₂-induced toxicology by suppressing autophagy in HepG2 cells. CircRNAs are increasingly perceived as vital regulators in the process of autophagy. However, it remain unclear whether circRNAs are involved in CAPE's protection against CdCl₂-induced autophagy. Under this context, the roles of CircRNA (hsa_circ_0040768) in CAPE's protection against CdCl₂-induced damage were investigated by PCR and Western blot. Results showed that CAPE significantly (P < 0.05) increased cell viability via inhibiting CdCl₂-induced autophagy, and this process was regulated by hsa_circ_0040768/MAP1LC3B axis. Overexpressing hsa_circ_0040768 led to reduced cell viability and increased autophagy in CAPE-treated HepG2 cells exposed to CdCl₂. In contrast, silencing hsa_circ_0040768 showed similar protective effect to CAPE. These results show for the first time the involvement of the hsa_circ_0040768/MAP1LC3B axis in the CAPE's protection against CdCl₂-induced autophagy, and provide novel insights into the pathogenesis and potential prevention/treatment of cadmium-associated diseases.

Metformin and rapamycin protect cells from vital dye-induced damage in retinal pigment epithelial cells and in vivo

PURPOSE

To evaluate the effect of autophagy inducers on damage caused by vital dye in adult human RPE (ARPE) cells and in a rat model.

METHODS

ARPE-19 cells were exposed to ICG or BBG (0.05 mg/ml) with rapamycin (200 nM) or metformin (2 mM) for 30 min and treated with or without 20 μM chloroquine (CQ) to identify the protein levels of LC3 and SQSTM1 by immunoblotting. In vivo study was performed by injecting 10 μl 0.05% ICG and 0.25% BBG into the subretinal space of the rat eyes, and/or co-treated them with metformin and rapamycin. The retinas were used to determine autophagy with the LC3-II level and apoptosis with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay.

RESULTS

In this study, both ICG and BBG inhibited autophagy flux in adult human retinal pigment epithelium cells (ARPE-19), whereas only ICG consistently reduced autophagy in the retina of rats. Moreover, rapamycin and metformin induced autophagic flux in ARPE-19 cells and increased the LC3-II level in retinal tissues exposed to vital dyes. Both ICG and BBG increased apoptosis in the retina of rats. However, both rapamycin and metformin induced autophagy and reduced the apoptosis caused by vital dyes.

CONCLUSION

Taken together, these results suggest that rapamycin and metformin may diminish vital dye-induced retinal damage in vivo through activation of autophagy.

Association of ATG4B and Phosphorylated ATG4B Proteins with Tumorigenesis and Prognosis in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the major leading causes of cancer death worldwide due to the limited availability of biomarkers and therapeutic targets. Autophagy related protease 4B (ATG4B) is an essential protease for the autophagy machinery, and ATG4B phosphorylation at Ser383/392 increases its proteolytic activity. ATG4B expression and activation are crucial for cancer cell proliferation and invasion. However, the clinical relevance of ATG4B and phospho-Ser383/392-ATG4B for OSCC remains unknown, particularly in buccal mucosal SCC (BMSCC) and tongue SCC (TSCC). With a tissue microarray comprising specimens from 498 OSCC patients, including 179 BMSCC and 249 TSCC patients, we found that the protein levels of ATG4B and phospho-Ser383/392-ATG4B were elevated in the tumor tissues of BMSCC and TSCC compared with those in adjacent normal tissues. High protein levels of ATG4B were significantly associated with worse disease-specific survival (DSS) in OSCC patients, particularly in patients with tumors at advanced stages. In contrast, phospho-Ser383/392-ATG4B expression was correlated with poor disease-free survival (DFS) in TSCC patients. Moreover, ATG4B protein expression was positively correlated with phospho-Ser383/392-ATG4B expression in both BMSCC and TSCC. However, high coexpression levels of ATG4B and phospho-Ser383/392-ATG4B were associated with poor DFS only in TSCC patients, whereas they had no significant association with DSS in BMSCC and TSCC patients. In addition, silencing ATG4B with an antisense oligonucleotide (ASO) or small interfering RNA (siRNA) diminished cell proliferation of TW2.6 and SAS oral cancer cells. Further, knockdown of ATG4B reduced cell migration and invasion of oral cancer cells. Taken together, these findings suggest that ATG4B might be a biomarker for diagnosis/prognosis of OSCC and a potential therapeutic target for OSCC patients.

Prognostic role of RECK in pathological outcome-dependent buccal mucosa squamous cell carcinoma

BACKGROUND

Buccal mucosal squamous cell carcinoma (BMSCC) is an aggressive oral cancer. Moreover, reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is a well-known tumor suppressor in many cancers. Our aim was to investigate the association of RECK expression with prognosis in BMSCC patients with different clinicopathological features.

MATERIALS AND METHODS

The expression level of RECK was determined by immunohistochemistry using tissue microarrays containing specimens from 193 BMSCC patients. The association of RECK expression with outcomes in BMSCC patients stratified by different clinicopathological features was analyzed by Cox proportional hazards models.

RESULTS

The low expression level of RECK was associated with shorter disease-specific survival, especially in patients with age >40 years, moderate or poor cell differentiation, advanced pathological stage, and history of postoperative radiotherapy. However, the low expression level of RECK was not associated with poor disease-free survival, except in BMSCC patients with age ≦40 years, advanced pathological stage and lymph node metastasis. Furthermore, RECK-knockdowned cells showed higher cell viability and abilities of invasion/migration, indicating that RECK might be a tumor suppressor for tumor progression in oral cancer.

CONCLUSION

The low expression of RECK might be a potential prognostic biomarker for pathological outcome-dependent BMSCC patients.

Guanylate-binding protein 6 is a novel biomarker for tumorigenesis and prognosis in tongue squamous cell carcinoma

OBJECTIVES

Guanylate-binding protein 6 (GBP6) is a member of the guanylate-binding protein family, and its role in cancer has not yet been reported. We aimed to investigate the clinical significance of GBP6 in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Next-generation sequencing was applied for analyzing differential gene expression profiling between corresponding tumor adjacent normal (CTAN) and tumor tissue from two paired OSCC patients. Real-time PCRs (RT-PCRs) were used to investigate the gene expression level of GBP6 of CTAN and tumor tissue samples from 14 TSCC patients. Immunohistochemistry was used to investigate the protein expression level of GBP6 in tumor tissues and paired CTAN tissues from 488 OSCC patients, including 183 buccal mucosa squamous cell carcinoma (BMSCC), 245 tongue squamous cell carcinoma (TSCC), and 60 lip squamous cell carcinoma (LSCC) patients.

RESULTS

Compared with CTAN tissues of OSCC patients, GBP6 is identified as a downregulated gene using the NGS platform, which was confirmed in 14 OSCC patients by RT-PCR. Moreover, protein expression level of GBP6 in tumor tissues was lower than that in CTAN tissues and the low GBP6 expression was correlated with poor cell differentiation/lymph node metastasis in TSCC patients. In addition, TSCC patients with low expression levels of GBP6 had poor disease-specific survival rate.

CONCLUSION

The low expression of GBP6 was associated with tumorigenesis and poor prognosis in OSCC patients, especially in TSCC patients.

CLINICAL RELEVANCE

GBP6 may serve as a novel favorable diagnostic and prognostic biomarker in TSCC patients.

CircCDR1as upregulates autophagy under hypoxia to promote tumor cell survival via AKT/ERK½/mTOR signaling pathways in oral squamous cell carcinomas

Autophagy, as an important non-selective degradation mechanism, could promote tumor initiation and progression by maintaining cellular homeostasis and the cell metabolism as well as cell viability. CircCDR1as has been shown to function as an oncogene in cancer progression, however, it remains largely unknown as to how autophagy is regulated by circCDR1as in oral squamous cell carcinoma (OSCC). In this study, we validated the functional roles of circCDR1as in regulation of autophagy in OSCC cells and further investigated how circCDR1as contributed to cell survival via up-regulating autophagy under a hypoxic microenvironment by using combination of human tissue model, in vitro cell experiments and in vivo mice model. We found that hypoxia promoted the expression level of circCDR1as in OSCC cells and elevated autophagy. In addition, circCDR1as further increased hypoxia-mediated autophagy by targeting multiple key regulators of autophagy. We revealed that circCDR1as enhanced autophagy in OSCC cells via inhibition of rapamycin (mTOR) activity and upregulation of AKT and ERK_½ pathways. Overexpression of circCDR1as enhanced OSCC cells viability, endoplasmic reticulum (ER) stress, and inhibited cell apoptosis under a hypoxic microenvironment. Moreover, circCDR1as promoted autophagy in OSCC cells by sponging miR-671-5p. Collectively, these results revealed that high expression of circCDR1as enhanced the viability of OSCC cells under a hypoxic microenvironment by promoting autophagy, suggesting a novel treatment strategy involving circCDR1as and the inhibition of autophagy in OSCC cells.

Manoalide Preferentially Provides Antiproliferation of Oral Cancer Cells by Oxidative Stress-Mediated Apoptosis and DNA Damage

Marine sponge-derived manoalide has a potent anti-inflammatory effect, but its potential application as an anti-cancer drug has not yet been extensively investigated. The purpose of this study is to evaluate the antiproliferative effects of manoalide on oral cancer cells. MTS assay at 24 h showed that manoalide inhibited the proliferation of six types of oral cancer cell lines (SCC9, HSC3, OC2, OECM-1, Ca9-22, and CAL 27) but did not affect the proliferation of normal oral cell line (human gingival fibroblasts (HGF-1)). Manoalide also inhibits the ATP production from 3D sphere formation of Ca9-22 and CAL 27 cells. Mechanically, manoalide induces subG1 accumulation in oral cancer cells. Manoalide also induces more annexin V expression in oral cancer Ca9-22 and CAL 27 cells than that of HGF-1 cells. Manoalide induces activation of caspase 3 (Cas 3), which is a hallmark of apoptosis in oral cancer cells, Ca9-22 and CAL 27. Inhibitors of Cas 8 and Cas 9 suppress manoalide-induced Cas 3 activation. Manoalide induces higher reactive oxygen species (ROS) productions in Ca9-22 and CAL 27 cells than in HGF-1 cells. This oxidative stress induction by manoalide is further supported by mitochondrial superoxide (MitoSOX) production and mitochondrial membrane potential (MitoMP) destruction in oral cancer cells. Subsequently, manoalide-induced oxidative stress leads to DNA damages, such as γH2AX and 8-oxo-2’-deoxyguanosine (8-oxodG), in oral cancer cells. Effects, such as enhanced antiproliferation, apoptosis, oxidative stress, and DNA damage, in manoalide-treated oral cancer cells were suppressed by inhibitors of oxidative stress or apoptosis, or both, such as N-acetylcysteine (NAC) and Z-VAD-FMK (Z-VAD). Moreover, mitochondria-targeted superoxide inhibitor MitoTEMPO suppresses manoalide-induced MitoSOX generation and γH2AX/8-oxodG DNA damages. This study validates the preferential antiproliferation effect of manoalide and explores the oxidative stress-dependent mechanisms in anti-oral cancer treatment.

SQSTM1/p62 is involved in docosahexaenoic acid-induced cellular autophagy in glioblastoma cell lines

Docosahexaenoic acid (DHA) is the most abundant n-3 polyunsaturated fatty acid in the human brain and works as an anticancer agent to induce cell cycle arrest and apoptosis in glioblastoma multiforme (GBM) cell lines. However, little is known about the connection between DHA and autophagy in GBM cells. We found that high-dose DHA caused cellular autophagy in cultured U251 and U118 GBM cell lines, but there was no effect with a low dose. Moreover, after treatment with a high dose of DHA at 12, 24, and 48 h, the protein expression of SQSTM1/p62 decreased in DHA-treated U251 cells at 12 and 24 h, but increased at 48 h, while in DHA-treated U118 cells, the protein expression increased at all time points. Interestingly, the level of SQSTM1/p62 mRNA was elevated in both DHA-treated U251 and U118 cells at all time points, indicating that DHA activated SQSTM1/p62 transcription in both cell lines. Furthermore, downregulation of SQSTM1/p62 by siRNA attenuated DHA-induced cellular autophagy in both cell lines. This report confirms that high-dose DHA induces cellular autophagy in GBM cells, and demonstrates that SQSTM1/p62 acts as a regulator and participates in DHA-induced autophagy.

The MAP3K7-mTOR Axis Promotes the Proliferation and Malignancy of Hepatocellular Carcinoma Cells

Targeted therapy is currently limited for patients with hepatocellular carcinoma (HCC) due to the lack of suitable targets. Kinases play pivotal roles in many cellular biological processes, whereas dysregulation of kinases may lead to various diseases, particularly cancer. However, the role of kinases in HCC malignancy remains unclear. In this study, we employed a kinome small interfering RNA (siRNA) library, comprising 710 kinase-related genes, to screen whether any kinases were essential for cell proliferation in various HCC cell lines. Through a kinome siRNA library screening, we found that MAP3K7 was a crucial gene for HCC cell proliferation. Pharmacological or genetic ablation of MAP3K7 diminished the growth, migration, and invasion of HCC cells, including primary HCC cells. Stable knockdown of MAP3K7 attenuated tumor formation in a spheroid cell culture model and tumor xenograft mouse model. In addition, silencing MAP3K7 reduced the phosphorylation and expression of mammalian target of rapamycin (mTOR) in HCC cells. MAP3K7 expression was positively correlated with mTOR expression in tumors of patients with HCC. Higher co-expression of MAP3K7 and mTOR was significantly associated with poor prognosis of HCC. Taken together, our results revealed that the MAP3K7-mTOR axis might promote tumorigenesis and malignancy, which provides a potential marker or therapeutic target for HCC patients.

Long non-coding RNAs in Oral squamous cell carcinoma: biologic function, mechanisms and clinical implications

There is growing evidence that regions of the genome that cannot encode proteins play an important role in diseases. These regions are usually transcribed into long non-coding RNAs (lncRNAs). LncRNAs, little or no coding potential, are defined as capped transcripts longer than 200 nucleotides. New sequencing technologies have shown that a large number of aberrantly expressed lncRNAs are associated with multiple cancer types and indicated they have emerged as an important class of pervasive genes during the development and progression of cancer. However, the underlying mechanism in cancer is still unknown. Therefore, it is necessary to elucidate the lncRNA function. Notably, many lncRNAs dysregulation are associated with Oral squamous cell carcinoma (OSCC) and affect various aspects of cellular homeostasis, including proliferation, survival, migration or genomic stability. This review expounds the up- or down-regulation of lncRNAs in OSCC and the molecular mechanisms by which lncRNAs perform their function in the malignant cell. Finally, the potential of lncRNAs as non-invasive biomarkers for OSCC diagnosis are also described. LncRNAs hold promise as prospective novel therapeutic targets, but more research is needed to gain a better understanding of their biologic function.