Inhibiting Forkhead box K1 induces autophagy to reverse epithelial-mesenchymal transition and metastasis in gastric cancer by regulating Myc-associated zinc finger protein in an acidic microenvironment

HDAC1 and FOXK1 mediate EGFR-TKI resistance of non-small cell lung cancer through miR-33a silencing

BACKGROUND

The development of acquired EGFR-TKI treatment resistance is still a major clinical challenge in the treatment of non-small cell lung cancer (NSCLC). This study aimed to investigate the role of HDAC1/FOXK1/miR-33a signaling in EGFR-TKI resistance.

METHODS

The expression levels of miR-33a, HDAC1, and FOXK1 were examined using quantitative polymerase chain reaction (PCR) and bioinformatics analysis. Cell proliferation, migration, and apoptosis were explored by cell number assay, Transwell, and flow cytometry assays, respectively. After overexpression or knockdown of HDAC1, miR-33a expression in the cells, cell functions were tested. Immunoprecipitation and correlation analyses were used to evaluate the interaction between HDAC1 and FOXK1 protein. The tumor-suppressive role of miR-33a was investigated by animal experiments.

RESULTS

The suppression of miR-33a increased TKI resistance by affecting cell proliferation, migration, and apoptosis in gefitinib-resistant cells. HDAC1 is the key upstream molecule that inhibits miR-33 expression. HDAC1 upregulation increased gefitinib resistance by its binding to FOXK1 in cells to silence miR-33a expression. MiR-33a overexpression exerts tumor-suppressive effects by negatively regulating ABCB7 and p70S6K1 expression. Moreover, overexpression of miR-33a inhibited tumor growth in a xenograft nude mouse model.

CONCLUSIONS

HDAC1/FOXK1 upregulation and miR-33a silencing are new mechanisms of EGFR-TKI resistance in NSCLC.

OTUB1 accelerates hepatocellular carcinoma by stabilizing RACK1 via its non-canonical ubiquitination

BACKGROUND

Dysregulated ubiquitination modification occupies a pivotal role in hepatocellular carcinoma (HCC) tumorigenesis and progression. The ubiquitin aldehyde binding 1 (OTUB1) was aberrantly upregulated and exhibited the pro-tumorigenic function in HCC. However, the underlying mechanisms and responsible targets of OTUB1 remain unclear.

METHODS

First, bioinformatics analysis, western blot and immunohistochemistry staining were applied to analyze OTUB1 expression in HCC specimens. Then, immunoprecipitation assay-tandem mass spectrometry (MS) combined with the gene set enrichment analysis (GSEA) was used to explore the downstream target of OTUB1. Co-immunoprecipitation and ubiquitination assays were used to identify the mechanisms involved. Finally, we explored the regulatory effect of MAZ on OTUB1 through ChIP-qPCR and dual-luciferase reporter assay.

RESULTS

OTUB1 was broadly elevated in HCC tissues and promoted the proliferation and metastasis of HCC in vitro and in vivo. The receptor for activated C kinase 1 (RACK1) performed as a functional partner of OTUB1 and its hyperactivation was associated with aggressive development and other malignant features in HCC by activating oncogenes transcription. Mechanistically, OTUB1 directly bound to RACK1 at its C-terminal domain and decreased the K48-linked ubiquitination of RACK1 through its non-canonical suppression of ubiquitination activity, which stabilized RACK1 protein levels in HCC cells. Therefore, OTUB1 significantly increased multiple oncogenes expression and activated PI3K/AKT and FAK/ERK signaling in a RACK1-dependent manner in HCC. Moreover, the transcription factor MAZ upregulated OTUB1 expression through identifying a putative response element of OTUB1 promoter area.

CONCLUSIONS

Our findings might provide a new therapeutic strategy for HCC by modifying the MAZ-OTUB1-RACK1 axis.

Dysregulation of autophagy in gastric carcinoma: Pathways to tumor progression and resistance to therapy

The considerable death rates and lack of symptoms in early stages of gastric cancer (GC) make it a major health problem worldwide. One of the most prominent risk factors is infection with Helicobacter pylori. Many biological processes, including those linked with cell death, are disrupted in GC. The cellular "self-digestion" mechanism necessary for regular balance maintenance, autophagy, is at the center of this disturbance. Misregulation of autophagy, however, plays a role in the development of GC. In this review, we will examine how autophagy interacts with other cell death processes, such as apoptosis and ferroptosis, and how it affects the progression of GC. In addition to wonderful its role in the epithelial-mesenchymal transition, it is engaged in GC metastasis. The role of autophagy in GC in promoting drug resistance stands out. There is growing interest in modulating autophagy for GC treatment, with research focusing on natural compounds, small-molecule inhibitors, and nanoparticles. These approaches could lead to breakthroughs in GC therapy, offering new hope in the fight against this challenging disease.

The mechanism by which SIRT1 regulates autophagy and EMT in drug-resistant oesophageal cancer cells

Cancer cell resistance presents a significant clinical challenge. The mechanisms underlying drug resistance in cancer cells are intricate and remain incompletely understood. Notably, tumor cell resistance often coincides with the epithelial-mesenchymal transition (EMT). In this study, we observed an elevation in autophagy levels following the development of drug resistance in oesophageal cancer cells. Inhibition of autophagy led to a reduction in drug-resistant cell migration and the inhibition of EMT. Furthermore, we identified an upregulation of SIRT1 expression in drug-resistant oesophageal cancer cells. Subsequent inhibition of SIRT1 expression in drug-resistant cells resulted in the suppression of autophagy levels, migration ability, and the EMT process. Our additional investigations revealed that a SIRT1 inhibitor effectively curbed tumor growth in human oesophageal cancer xenograft model mice (TE-1, TE-1/PTX) without evident toxic effects. This mechanism appears to be associated with the autophagy levels within the tumor tissue.

Forkhead Box Q1 is a novel regulator of autophagy in breast cancer cells

Forkhead Box Q1 (FoxQ1) transcription factor is overexpressed in luminal-type and basal-type human breast cancers when compared to normal mammary tissue. This transcription factor is best known for its role in promotion of breast cancer stem-like cells and epithelial to mesenchymal transition. The present study documents a novel function of FoxQ1 in breast cancer cells. Overexpression of FoxQ1 in basal-like SUM159 cells and luminal-type MCF-7 cells resulted in increased conversion of microtubule-associated protein light chain 3 beta-I (LC3B-I) to LC3B-II, which is a hallmark of autophagy. Autophagy induction by FoxQ1 overexpression was confirmed by visualization of LC3B puncta as well as by transmission electron microscopy. Expression profiling for genes implicated in autophagy regulation revealed upregulation of many genes, including ATG4B, ATG16L1, CTSS, CXCR4 and so forth but downregulation of BCL2L1, DRAM1, TNF, ULK2 and so forth by FoxQ1 overexpression in SUM159 cells. Western blot analysis confirmed upregulation of ATG4B and CXCR4 proteins by FoxQ1 overexpression in both SUM159 and MCF-7 cells. Chromatin immunoprecipitation assay revealed recruitment of FoxQ1 at the promoter of ATG4B. Pharmacological inhibition of ATG4B using S130 significantly increased apoptosis induction by DOX in empty vector transfected as well as FoxQ1 overexpressing SUM159 and MCF-7 cells but this effect was statistically significantly lowered by FoxQ1 overexpression indicating the protective role of FoxQ1 on apoptosis. Treatment of SUM159 cells with S130 and DOX enhanced LC3B-II level in both empty vector transfected cells and FoxQ1 overexpressing SUM159 cells but not in FoxQ1 overexpressing MCF-7 cells. In conclusion, FoxQ1 is a novel regulator of autophagy.

MIR663AHG as a competitive endogenous RNA regulating TGF-β-induced epithelial proliferation and epithelial-mesenchymal transition in benign prostate hyperplasia

Benign prostate hyperplasia (BPH) is the most commonly seen disease among aging males. Transforming growth factor(TGF)-β-mediated epithelial-mesenchymal transition (EMT) and epithelial overproliferation might be central events in BPH etiology and pathophysiology. In the present study, long noncoding RNA MIR663AHG, miR-765, and FOXK1 formed a competing endogenous RNAs network, modulating TGF-β-mediated EMT and epithelial overproliferation in BPH-1 cells. miR-765 expression was downregulated in TGF-β-stimulated BPH-1 cells; miR-765 overexpression ameliorated TGF-β-mediated EMT and epithelial overproliferation in BPH-1 cells. MIR663AHG directly targeted miR-765 and negatively regulated miR-765; MIR663AHG knockdown also attenuated TGF-β-induced EMT and epithelial overproliferation in BPH-1 cells, whereas miR-765 inhibition attenuated MIR663AHG knockdown effects on TGF-β-stimulated BPH-1 cells. miR-765 directly targeted FOXK1 and negatively regulated FOXK1. FOXK1 knockdown attenuated TGF-β-induced EMT and epithelial overproliferation and promoted autophagy in BPH-1 cells, and partially attenuated miR-765 inhibition effects on TGF-β-stimulated BPH-1 cells. In conclusion, this study provides a MIR663AHG/miR-765/FOXK1 axis modulating TGF-β-induced epithelial proliferation and EMT, which might exert an underlying effect on BPH development and act as therapeutic targets for BPH treatment regimens.

Construction of a lipid metabolism-related and immune-associated prognostic score for gastric cancer

BACKGROUND

The interaction between tumor cells and immune or non-immune stromal cells creates a unique tumor microenvironment, which plays an important role in the growth, invasion and metastasis of gastric cancer (GC).

METHODS

The candidate genes were selected to construct risk-score by univariate and multivariate Cox regression analysis. Nomograms were constructed by combining clinical pathological factors, and the model performance was evaluated by receiver operating characteristic curve, decision curve analysis, net reclassification improvement and integrated discrimination improvement. The functional enrichment between high-risk group (HRisk) and low-risk group (LRisk) was explored through GO, KEGG, GSVA and ssGSEA. CIBERSORT, quanTIseq and xCell were used to explore the immune cell infiltration between HRisk and LRisk. The relevant EMT scores, macrophage infiltration scores and various metabolic scores were calculated through the "IOBR" package and analyzed visually.

RESULTS

Through univariate and multivariate Cox regression analysis, we obtained the risk-score of fittings six lipid metabolism related genes (LMAGs). Through survival analysis, we found that risk-score has significant prognostic significance and can accurately reflect the metabolic level of patients. The AUCs of the nomogram model incorporating risk-score 1, 3 and 5 years were 0.725, 0.729 and 0.749 respectively. In addition, it was found that the inclusion of risk-score could significantly improve the prediction performance of the model. It was found that the arachidonic acid metabolism and prostaglandin synthesis were up-regulated in HRisk, and more tumor metastasis related markers and immune related pathways were also enriched. Further study found that HRisk had higher immune score and M2 macrophage infiltration. More importantly, the immune checkpoints of tumor associated macrophages involved in tumor antigen recognition disorders increased significantly. We also found that ST6GALNAC3 can promote arachidonic acid metabolism and up-regulate prostaglandin synthesis, increase M2 macrophage infiltration, induce epithelial mesenchymal transformation, and affect the prognosis of patients.

CONCLUSIONS

Our research found a novel and powerful LMAGs signature. Six-LMAGs features can effectively evaluate the prognosis of GC patients and reflect the metabolic and immune status. ST6GALNAC3 may be a potential prognostic marker to improve the survival rate and prognostic accuracy of GC patients, and may even be a potential biomarker of GC patients, indicating the response to immunotherapy.

TBK1 promotes thyroid cancer progress by activating the PI3K/Akt/mTOR signaling pathway

INTRODUCTION

Thyroid cancer has received increasing attention; however, its detailed pathogenesis and pathological processes remain unclear. We investigated the role of TANK-binding kinase 1 (TBK1) in the progression of thyroid cancer.

METHODS

The expression of TBK1 in thyroid cancer and normal control tissues was analyzed using real-time quantitative polymerase chain reaction. The function of TBK1 on thyroid cancer cells was detected using MTT, colony formation, wound healing, and Transwell assays. The xenograft assay was carried out to check on the role of TBK1 in thyroid cancer.

RESULTS

TBK1 was highly expressed in thyroid tumors. High expression of TBK1 raised viability, proliferation, migration, and invasion of thyroid cancer cells. Gene set enrichment analysis revealed that TBK1 activated the phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathway. In addition, Myc-associated zinc finger protein (MAZ) was overexpressed in thyroid cancer and transcriptionally activated BK1. MAZ silence reversed the effects of TBK1 overexpression on thyroid cancer progression. Cotransfection with MAZ small-interfering RNA(siRNA) and TBK1 siRNA did not strengthen the inhibitory effect of TBK1 silencing on the thyroid cancer cells. The xenograft tumor assay showed that TBK1 short hairpinRNA inhibited tumor growth.

CONCLUSION

MAZ silencing inhibited tumor progress of thyroid cancer cells, whereas this inhibitory effect was reversed by TBK1 overexpression.

Circular RNA Eps15-homology domain containing protein 2 motivates proliferation, glycolysis but refrains autophagy in non-small cell lung cancer via crosstalk with microRNA-3186-3p and forkhead box K1

Numerous studies have clarified the involvement of circular RNAs (circRNAs) in modulating malignant behavior of non-small cell lung cancer (NSCLC), while the concrete mechanism is not completely elucidated. The aim of the study was to figure out the latent functions and molecular mechanisms of circRNA Eps15-homology domain containing protein 2 (EHD2) on NSCLC proliferation, glycolysis and autophagy. The results clarified in NSCLC elevated expression of circEHD2 and declined expression of microRNA (miR)-3186-3p. Repressive circEHD2 or enhancive miR-3186-3p facilitated cell apoptosis rate and autophagy substrates LC3BII and Beclin-1, but curbed the colony-formation and DNA replication ability of NSCLC, glucose consumption, lactic acid production, glycolytic rate-limiting enzyme HK-2 and glutamine hydrolase GLS1 and P62, while overexpressed circEHD2 was adverse. Meanwhile, the impacts of repressive and elevated circEHD2 on NSCLC were turned around via reduced miR-3186-3p or forkhead box k1 (FOXK1) separately. Mechanically, FOXK1 was augmented via circEHD2's competitive integration of miR-3186-3p. Depressive circEHD2 refrained NSCLC tumor growth, which was accelerated via enhancive one. All in all, circEHD2 accelerates the proliferation and glycolysis of NSCLC, but refrains autophagy and apoptosis via strengthening FOXK1 via the adsorption of miR-3186-3p, which is supposed to be a latent molecular target for NSCLC therapy later.

Regulation of Autophagy by the Glycogen Synthase Kinase-3 (GSK-3) Signaling Pathway

Autophagy is a vital cellular mechanism that benefits cellular maintenance and survival during cell stress. It can eliminate damaged or long-lived organelles and improperly folded proteins to maintain cellular homeostasis, development, and differentiation. Impaired autophagy is associated with several diseases such as cancer, neurodegenerative diseases, and age-related macular degeneration (AMD). Several signaling pathways are associated with the regulation of the autophagy pathway. The glycogen synthase kinase-3 signaling pathway was reported to regulate the autophagy pathway. In this review, we will discuss the mechanisms by which the GSK-3 signaling pathway regulates autophagy. Autophagy and lysosomal function are regulated by transcription factor EB (TFEB). GSK-3 was shown to be involved in the regulation of TFEB nuclear expression in an mTORC1-dependent manner. In addition to mTORC1, GSK-3β also regulates TFEB via the protein kinase C (PKC) and the eukaryotic translation initiation factor 4A-3 (eIF4A3) signaling pathways. In addition to TFEB, we will also discuss the mechanisms by which the GSK-3 signaling pathway regulates autophagy by modulating other signaling molecules and autophagy inducers including, mTORC1, AKT and ULK1. In summary, this review provides a comprehensive understanding of the role of the GSK-3 signaling pathway in the regulation of autophagy.

Roles of Myc-associated zinc finger protein in malignant tumors

As an important transcription factor that is widely expressed in most tissues of the human body, Myc-associated zinc finger protein (MAZ) has been reported highly expressed in many malignant tumors and thought to be a promising therapeutic target for cancer treatment. In this review, we aim to offer a comprehensive understanding of MAZ regulation in malignant tumors. The carboxy terminal of MAZ protein contains six C2H2 zinc fingers, and its regulation of transcription is based on the interaction between the GC-rich DNA binding sites of target genes and its carboxy-terminal zinc finger motifs. MAZ protein has been found to activate or inhibit the transcriptional initiation process of many target genes, as well as play an important role in the transcriptional termination process of some target genes, so MAZ poses dual regulatory functions in the initiation and termination process of gene transcription. Through the transcriptional regulation of c-myc and Ras gene family, MAZ poses an important role in the occurrence and development of breast cancer, pancreatic cancer, prostate cancer, glioblastoma, neuroblastoma, and other malignant tumors. Our review shows a vital role of MAZ in many malignant tumors and provides novel insight for cancer diagnosis and treatment.

SIPL1, Regulated by MAZ, Promotes Tumor Progression and Predicts Poor Survival in Human Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer owing to a lack of effective targeted therapy and acquired chemoresistance. Here, we explored the function and mechanism of shank-interacting protein-like 1 (SIPL1) in TNBC progression.

METHODS

SIPL1 expression was examined in human TNBC tissues and cell lines by quantitative reverse transcription PCR, western blot, and immunohistochemistry. SIPL1 overexpression and silenced cell lines were established in BT-549 and MDA-MB-231 cells. The biological functions of SIPL1 in TNBC were studied in vitro using the CCK-8 assay, CellTiter-Glo Luminescent Cell Viability assay, caspase-3/8/9 assay, wound healing assay, and transwell assay and in vivo using a nude mouse model. The potential mechanisms underlying the effects of SIPL1 on TNBC progression were explored using bioinformatics analysis, luciferase reporter assays, and chromatin immunoprecipitation followed by qPCR.

RESULTS

SIPL1 expression was higher in human TNBC tissues and cell lines than in adjacent normal tissues and a breast epithelial cell line (MCF10A). High expression of SIPL1 was positively correlated with poor overall and disease-free survival in patients with TNBC. SIPL1 overexpression elevated and SIPL1 silencing repressed the malignant phenotypes of TNBC cells in vitro. SIPL1 overexpression promoted xenograft tumor growth in vivo. Myc-associated zinc-finger protein (MAZ) transcriptionally activated SIPL1. Finally, we found that SIPL1 promoted TNBC malignant phenotypes via activation of the AKT/NF-κB signaling pathways.

CONCLUSIONS

These results indicate that the MAZ/SIPL1/AKT/NF-κB axis plays a crucial role in promoting the malignant phenotypes of TNBC cells.

Traditional Chinese medicine for precancerous lesions of gastric cancer: A review

Gastric cancer (GC) is the fifth most common type of cancer and the third leading cause of death due to cancer worldwide. The gastric mucosa often undergoes many years of precancerous lesions of gastric cancer (PLGC) stages before progressing to gastric malignancy. Unfortunately, there are no effective Western drugs for patients with PLGC. In recent years, traditional Chinese medicine (TCM) has been proven effective in treating PLGC. Classical TCM formulas and chemical components isolated from some Chinese herbal medicines have been administered to treat PLGC, and the main advantage is their comprehensive intervention with multiple approaches and multiple targets. In this review, we focus on recent studies using TCM treatment for PLGC, including clinical observations and experimental research, with a focus on targets and mechanisms of drugs. This review provides some ideas and a theoretical basis for applying TCM to treat PLGC and prevent GC.

Increased ATG5 Expression Predicts Poor Prognosis and Promotes EMT in Cervical Carcinoma

Cervical cancer has the second-highest incidence and mortality of female malignancy. The major causes of mortality in patients with cervical cancer are invasion and metastasis. The epithelial–mesenchymal transition (EMT) process plays a major role in the acquisition of metastatic potential and motility. Autophagy-related genes (ARGs) are implicated in the EMT process, and autophagy exerts a dual function in EMT management at different phases of tumor progression. However, the role of specific ARGs during the EMT process has not yet been reported in cervical cancer. Based on the data from the Cancer Genome Atlas (TCGA) cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) sequencing database, we performed the prognosis analysis for those ARGs obtained from the Human Autophagy database. ATG5 was identified as the only important harmful marker influencing survival of cervical cancer patients by univariate Cox regression (HR 1.7; 95% CI: 1.0–2.8, p = 0.047), and the 5-years survival rate for the high- and low-ATG5 expression groups was 0.486 (0.375–0.631) and 0.782 (0.708–0.863), respectively. TCGA CESC methylation data showed that eight methylation sites of ATG5 could also be significantly associated with the overall survival (OS) of cervical cancer patients. Single-sample gene-set enrichment and gene functional enrichment results showed that ATG5 was correlated with some cancer-related pathways, such as phagocytosis-related genes, endocytosis-related genes, immune-related genes, EMT score, and some EMT signature-related genes. Next, cell migration and invasion assay and Western blot were applied to detect the function of ATG5 in EMT of cervical cancer. In cervical cancer cells, ATG5 knockdown resulted in attenuation of migration and invasion. The functional study showed that knockdown of ATG5 could reverse EMT process by P-ERK, P-NFκBp65, P-mTOR pathways, and so on. In conclusion, the present study implies that ATG5 was a major contributor to EMT regulation and poor prognosis in cervical cancer.

Tumor microenvironment acidity modulates ROR1 to promote epithelial-mesenchymal transition and hepatocarcinoma metastasis

The tendency of hepatocarcinoma to metastasize results in a high rate of mortality, making it a hot research topic in cancer studies. Although an acidic tumor microenvironment has been proven to promote cancer metastasis, the underlying regulatory mechanisms remain poorly defined. Here, we found that acidic conditions significantly enhanced cell migration and invasion ability in hepatocellular carcinoma, and the expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) was distinctly upregulated in acid-treated cells. In addition, siRNA-mediated knockdown of ROR1 could effectively inhibit acid-induced cell migration, invasion and epithelial-mesenchymal transition (EMT). Importantly, neutralization of acidic environments with NaHCO3 could downregulate acid-stimulated ROR1 expression, thereby retarding cell metastatic potential. Notably, the formation of metastatic nodules was significantly increased after intrapulmonary injection of acid-stimulated cancer cells, and this was inhibited by pretreating with NaHCO3. In summary, we reveal that an acidic tumor microenvironment modulates ROR1 expression to promote tumor metastasis, providing not only a better understanding of molecular mechanisms related to metastasis, but also a promising target for tumor management.

C-Myc Signaling Pathway in Treatment and Prevention of Brain Tumors

Brain tumors are responsible for high morbidity and mortality worldwide. Several factors such as the presence of blood-brain barrier (BBB), sensitive location in the brain, and unique biological features challenge the treatment of brain tumors. The conventional drugs are no longer effective in the treatment of brain tumors, and scientists are trying to find novel therapeutics for brain tumors. In this way, identification of molecular pathways can facilitate finding an effective treatment. c-Myc is an oncogene signaling pathway capable of regulation of biological processes such as apoptotic cell death, proliferation, survival, differentiation, and so on. These pleiotropic effects of c-Myc have resulted in much fascination with its role in different cancers, particularly brain tumors. In the present review, we aim to demonstrate the upstream and down-stream mediators of c-Myc in brain tumors such as glioma, glioblastoma, astrocytoma, and medulloblastoma. The capacity of c-Myc as a prognostic factor in brain tumors will be investigated. Our goal is to define an axis in which the c-Myc signaling pathway plays a crucial role and to provide direction for therapeutic targeting in these signaling networks in brain tumors.

Emerging Autophagy Functions Shape the Tumor Microenvironment and Play a Role in Cancer Progression - Implications for Cancer Therapy

The tumor microenvironment (TME) is a complex environment where cancer cells reside and interact with different types of cells, secreted factors, and the extracellular matrix. Additionally, TME is shaped by several processes, such as autophagy. Autophagy has emerged as a conserved intracellular degradation pathway for clearance of damaged organelles or aberrant proteins. With its central role, autophagy maintains the cellular homeostasis and orchestrates stress responses, playing opposite roles in tumorigenesis. During tumor development, autophagy also mediates autophagy-independent functions associated with several hallmarks of cancer, and therefore exerting several effects on tumor suppression and/or tumor promotion mechanisms. Beyond the concept of degradation, new different forms of autophagy have been described as modulators of cancer progression, such as secretory autophagy enabling intercellular communication in the TME by cargo release. In this context, the synthesis of senescence-associated secretory proteins by autophagy lead to a senescent phenotype. Besides disturbing tumor treatment responses, autophagy also participates in innate and adaptive immune signaling. Furthermore, recent studies have indicated intricate crosstalk between autophagy and the epithelial-mesenchymal transition (EMT), by which cancer cells obtain an invasive phenotype and metastatic potential. Thus, autophagy in the cancer context is far broader and complex than just a cell energy sensing mechanism. In this scenario, we will discuss the key roles of autophagy in the TME and surrounding cells, contributing to cancer development and progression/EMT. Finally, the potential intervention in autophagy processes as a strategy for cancer therapy will be addressed.

Autophagy Takes Center Stage as a Possible Cancer Hallmark

Cancer remains one of the leading causes of death worldwide, despite significant advances in cancer research and improvements in anticancer therapies. One of the major obstacles to curing cancer is the difficulty of achieving the complete annihilation of resistant cancer cells. The resistance of cancer cells may not only be due to intrinsic factors or factors acquired during the evolution of the tumor but may also be caused by chemotherapeutic treatment failure. Conversely, autophagy is a conserved cellular process in which intracellular components, such as damaged organelles, aggregated or misfolded proteins and macromolecules, are degraded or recycled to maintain cellular homeostasis. Importantly, autophagy is an essential mechanism that plays a key role in tumor initiation and progression. Depending on the cellular context and microenvironmental conditions, autophagy acts as a double-edged sword, playing a role in inducing apoptosis or promoting cell survival. In this review, we propose several scenarios in which autophagy could contribute to cell survival or cell death. Moreover, a special focus on novel promising targets and therapeutic strategies based on autophagic resistant cells is presented.