The multifaceted role of autophagy in cancer and the microenvironment

The emerging roles of miRNA-mediated autophagy in ovarian cancer

Ovarian cancer is one of the common tumors of the female reproductive organs. It has a high mortality rate, is highly heterogeneous, and early detection and primary prevention are very complex. Autophagy is a cellular process in which cytoplasmic substrates are targeted for degradation in lysosomes through membrane structures called autophagosomes. The periodic elimination of damaged, aged, and redundant cellular molecules or organelles through the sequential translation between amino acids and proteins by two biological processes, protein synthesis, and autophagic protein degradation, helps maintain cellular homeostasis. A growing number of studies have found that autophagy plays a key regulatory role in ovarian cancer. Interestingly, microRNAs regulate gene expression at the posttranscriptional level and thus can regulate the development and progression of ovarian cancer through the regulation of autophagy in ovarian cancer. Certain miRNAs have recently emerged as important regulators of autophagy-related gene expression in cancer cells. Moreover, miRNA analysis studies have now identified a sea of aberrantly expressed miRNAs in ovarian cancer tissues that can affect autophagy in ovarian cancer cells. In addition, miRNAs in plasma and stromal cells in tumor patients can affect the expression of autophagy-related genes and can be used as biomarkers of ovarian cancer progression. This review focuses on the potential significance of miRNA-regulated autophagy in the diagnosis and treatment of ovarian cancer.

NUPR1 induces autophagy and promotes the progression of Esophageal squamous cell carcinoma via the MAPK-mTOR pathway

PURPOSE

Esophageal squamous cell carcinoma (ESCC) is a dominant pathological type in China. NUPR1 is a complex molecule implicated in various physiological and biological functions whose expression is upregulated in response to stress. Furthermore, autophagy is a vital physiological mechanism in the onset and metastasis of malignancies. This study aims to uncover the influence of NUPR1 on ESCC occurrence and development by regulating autophagy while also exploring its association with the MAPK signaling pathway.

METHODS

First, the differences in NUPR1 between ESCC and normal tissues were analyzed through online databases. Subsequently, the pathological tissues of clinical samples were stained and scored using immunohistochemistry. And NUPR1 expression in ESCC cells was investigated, as was the function of NUPR1 in the modulation of ESCC's malignant behavior. Furthermore, a nude mouse ESCC xenograft model was developed. Finally, RNA sequencing was performed on NUPR1-downregulated ESCC cells, which was verified using WB.

RESULTS

Our findings initially uncovered differences in the expression of NUPR1 in ESCC and normal tissues. In vitro experiments demonstrated that NUPR1 downregulation significantly inhibited ESCC cell proliferation, invasion, and migration, as well as promoted their apoptosis. Our xenograft model exhibited significant inhibition of ESCC tumors upon NUPR1 downregulation. Subsequently, RNA sequencing uncovered that NUPR1 regulates its malignant biological behavior through MAPK-mTOR signaling pathway. Finally, we found that NUPR1 downregulation can inhibit autophagic flux in ESCC.

CONCLUSION

Collectively, our findings show that NUPR1 enhances the progression of ESCC by triggering autophagy and is associated with the MAPK-mTOR signaling pathway.

Potential role of p53 deregulation in modulating immune responses in human malignancies: A paradigm to develop immunotherapy

The crucial role played by the oncogenic expression of TP53, stemming from mutation or amyloid formation, in various human malignancies has been extensively studied over the past two decades. Interestingly, the potential role of TP53 as a crucial player in modulating immune responses has provided new insight into the field of cancer biology. The loss of p53's transcriptional functions and/or the acquisition of tumorigenic properties can efficiently modulate the recruitment and functions of myeloid and lymphoid cells, ultimately leading to the evasion of immune responses in human tumors. Consequently, the oncogenic nature of the tumor suppressor p53 can dynamically alter the function of immune cells, providing support for tumor progression and metastasis. This review comprehensively explores the dual role of p53 as both the guardian of the genome and an oncogenic driver, especially in the context of regulation of autophagy, apoptosis, the tumor microenvironment, immune cells, innate immunity, and adaptive immune responses. Additionally, the focus of this review centers on how p53 status in the immune response can be harnessed for the development of tailored therapeutic strategies and their potential application in immunotherapy against human malignancies.

GBP2 enhances paclitaxel sensitivity in triple‑negative breast cancer by promoting autophagy in combination with ATG2 and inhibiting the PI3K/AKT/mTOR pathway

Chemoresistance is a major challenge in treating triple‑negative breast cancer (TNBC); chemotherapy remains the primary approach. The present study aimed to elucidate the role of guanylate‑binding protein 2 (GBP2) in activating autophagy in TNBC and its impact on the sensitivity of TNBC cells to paclitaxel (PTX). Transfection with lentivirus was performed to establish TNBC cell lines with stable, high GBP2 expression. The mRNA and protein levels of GBP2 expression were evaluated utilizing reverse transcription‑quantitative PCR and western blotting, respectively. Autophagy in TNBC cells was evaluated using immunoblotting, transmission electron microscopy and fluorescence microscopy. The PI3K/AKT/mTOR pathway proteins and their phosphorylation were detected by immunoblotting, and fluorescence co‑localization analysis was performed to evaluate the association between GBP2 and autophagy‑related protein 2 (ATG2). BALB/c NUDE mice were subcutaneously injected with GBP2 wild‑type/overexpressing MDA‑MB‑231 cells. Low GBP2 expression was detected in TNBC, which was associated with a poor prognosis. Overexpression of GBP2 suppressed cell growth, and especially enhanced autophagy in TNBC. Forced expression of GBP2 significantly increased the PTX sensitivity of TNBC cells, and the addition of autophagy inhibitors reversed this effect. GBP2 serves as a prognostic marker and exerts a notable inhibitory impact on TNBC. It functions as a critical regulator of activated autophagy by co‑acting with ATG2 and inhibiting the PI3K/AKT/mTOR pathway, which contributes to increasing sensitivity of TNBC cells to PTX. Therefore, GBP2 is a promising therapeutic target for enhancing TNBC treatment.

The multiple roles of autophagy in uveal melanoma and the microenvironment

PURPOSE

Uveal melanoma (UM) is the most common primary malignant intraocular tumor in adults, and effective clinical treatment strategies are still lacking. Autophagy is a lysosome-dependent degradation system that can encapsulate abnormal proteins, damaged organelles. However, dysfunctional autophagy has multiple types and plays a complex role in tumorigenicity depending on many factors, such as tumor stage, microenvironment, signaling pathway activation, and application of autophagic drugs.

METHODS

A systematic review of the literature was conducted to analyze the role of autophagy in UM, as well as describing the development of autophagic drugs and the link between autophagy and the tumor microenvironment.

RESULTS

In this review, we summarize current research advances regarding the types of autophagy, the mechanisms of autophagy, the application of autophagy inhibitors or agonists, autophagy and the tumor microenvironment. Finally, we also discuss the relationship between autophagy and UM.

CONCLUSION

Understanding the molecular mechanisms of how autophagy differentially affects tumor progression may help to design better therapeutic regimens to prevent and treat UM.

Autophagy: a necessary evil in cancer and inflammation

Autophagy, a highly regulated cellular process, assumes a dual role in the context of cancer. On the one hand, it functions as a crucial homeostatic pathway, responsible for degrading malfunctioning molecules and organelles, thereby maintaining cellular health. On the other hand, its involvement in cancer development and regression is multifaceted, contingent upon a myriad of factors. This review meticulously examines the intricacies of autophagy, from its molecular machinery orchestrated by Autophagy-Related Genes (ATG) initially discovered in yeast to the various modes of autophagy operative within cells. Beyond its foundational role in cellular maintenance, autophagy reveals context-specific functions in processes like angiogenesis and inflammation. Our analysis delves into how autophagy-related factors directly impact inflammation, underscoring their profound implications for cancer dynamics. Additionally, we extend our inquiry to explore autophagy's associations with cardiovascular conditions, neurodegenerative disorders, and autoimmune diseases, illuminating the broader medical relevance of this process. Furthermore, this review elucidates how autophagy contributes to sustaining hallmark cancer features, including stem cell maintenance, proliferation, angiogenesis, metastasis, and metabolic reprogramming. Autophagy emerges as a pivotal process that necessitates careful consideration in cancer treatment strategies. To this end, we investigate innovative approaches, ranging from enzyme-based therapies to MTOR inhibitors, lysosomal blockers, and nanoparticle-enabled interventions, all aimed at optimizing cancer treatment outcomes by targeting autophagy pathways. In summary, this comprehensive review provides a nuanced perspective on the intricate and context-dependent role of autophagy in cancer biology. Our exploration not only deepens our understanding of this fundamental process but also highlights its potential as a therapeutic target. By unraveling the complex interplay between autophagy and cancer, we pave the way for more precise and effective cancer treatments, promising better outcomes for patients.

The dual role of autophagy in the regulation of cancer treatment

As a catabolic process, autophagy through lysosomes degrades defective and damaged cellular materials to support homeostasis in stressful conditions. Therefore, autophagy dysregulation is associated with the induction of several human pathologies, including cancer. Although the role of autophagy in cancer progression has been extensively studied, many issues need to be addressed. The available evidence suggest that autophagy shows both cytoprotective and cytotoxic mechanisms. This dual role of autophagy in cancer has supplied a renewed interest in the development of novel and effective cancer therapies. Considering this, a deeper understanding of the molecular mechanisms of autophagy in cancer treatment is crucial. This article provides a summary of the recent advances regarding the dual and different mechanisms of autophagy-mediated therapeutic efficacy in cancer.

Autophagy-modulating biomembrane nanostructures: A robust anticancer weapon by modulating the inner and outer cancer environment

Recently, biomembrane nanostructures, such as liposomes, cell membrane-coated nanostructures, and exosomes, have demonstrated promising anticancer therapeutic effects. These nanostructures possess remarkable biocompatibility, multifunctionality, and low toxicity. However, their therapeutic efficacy is impeded by chemoresistance and radiotherapy resistance, which are closely associated with autophagy. Modulating autophagy could enhance the therapeutic sensitivity and effectiveness of these biomembrane nanostructures by influencing the immune system and the cancer microenvironment. For instance, autophagy can regulate the immunogenic cell death of cancer cells, antigen presentation of dendritic cells, and macrophage polarization, thereby activating the inflammatory response in the cancer microenvironment. Furthermore, combining autophagy-regulating drugs or genes with biomembrane nanostructures can exploit the targeting and long-term circulation properties of these nanostructures, leading to increased drug accumulation in cancer cells. This review explores the role of autophagy in carcinogenesis, cancer progression, metastasis, cancer immune responses, and resistance to treatment. Additionally, it highlights recent research advancements in the synergistic anticancer effects achieved through autophagy regulation by biomembrane nanostructures. The review also discusses the prospects and challenges associated with the future clinical translation of these innovative treatment strategies. In summary, these findings provide valuable insights into autophagy, autophagy-modulating biomembrane-based nanostructures, and the underlying molecular mechanisms, thereby facilitating the development of promising cancer therapeutics.

Preclinical evidence for preventive and curative effects of resveratrol on xenograft cholangiocarcinogenesis

Cholangiocarcinoma (CCA), the malignant tumor of bile duct epithelial cells, is a relatively rare yet highly lethal cancer. In this work, we tested the ability of Resveratrol (RV) to prevent and cure CCA xenograft in nude mice and investigated molecular mechanisms underpinning such anticancer effect. Human CCA cells were xenografted in mice that were or not treated prior to or after to transplantation with RV. Tumor growth was monitored and analyzed for the markers of cell proliferation, apoptosis, and autophagy. TCGA was interrogated for the molecules possibly targeted by RV. RV could inhibit the growth of human CCA xenograft when administered after implantation and could reduce the growth or even impair the implantation of the tumors when administered prior the transplantation. RV inhibited CCA cell proliferation, induced apoptosis with autophagy, and strongly reduced the presence of CAFs and production of IL-6. Interrogation of CCA dataset in TCGA database revealed that the expression of IL-6 Receptor (IL-6R) inversely correlated with that of MAP-LC3 and BECLIN-1, and that low expression of IL-6R and of MIK67, two pathways downregulated by RV, associated with better survival of CCA patients. Our data demonstrate that RV elicits a strong preventive and curative anticancer effect in CCA by limiting the formation of CAFs and their release of IL-6, and this results in up-regulation of autophagy and apoptosis in the cancer cells. These findings support the clinical use of RV as a primary line of prevention in patients exposed at risk and as an adjuvant therapeutics in CCA patients.

Role of autophagy in cancer-associated fibroblast activation, signaling and metabolic reprograming

Tumors not only consist of cancerous cells, but they also harbor several normal-like cell types and non-cellular components. cancer-associated fibroblasts (CAFs) are one of these cellular components that are found predominantly in the tumor stroma. Autophagy is an intracellular degradation and quality control mechanism, and recent studies provided evidence that autophagy played a critical role in CAF formation, metabolic reprograming and tumor-stroma crosstalk. Therefore, shedding light on the autophagy and its role in CAF biology might help us better understand the roles of CAFs and the TME in cancer progression and may facilitate the exploitation of more efficient cancer diagnosis and treatment. Here, we provide an overview about the involvement of autophagy in CAF-related pathways, including transdifferentiation and activation of CAFs, and further discuss the implications of targeting tumor stroma as a treatment option.

Rg3-enriched red ginseng extracts enhance apoptosis in CoCl2-stimulated breast cancer cells by suppressing autophagy

Background

Ginsenoside Rg3, a primary bioactive component of red ginseng, has anti-cancer effects. However, the effects of Rg3-enriched ginseng extract (Rg3RGE) on apoptosis and autophagy in breast cancer have not yet been investigated. In the present study, we explored the anti-tumor effects of Rg3RGE on breast cancer cells stimulated CoCl2, a mimetic of the chronic hypoxic response, and determined the operative mechanisms of action.

Methods

The inhibitory mechanisms of Rg3RGE on breast cancer cells, such as apoptosis, autophagy and ROS levels, were detected both in vitro. To determine the anti-cancer effects of Rg3RGE in vivo, the cancer xenograft model was used.

Results

Rg3RGE suppressed CoCl2-induced spheroid formation and cell viability in 3D culture of breast cancer cells. Rg3RGE promoted apoptosis by increasing cleaved caspase 3 and cleaved PARP and decreasing Bcl2 under the hypoxia mimetic conditions. Further, we identified that Rg3RGE promoted apoptosis by inhibiting lysosomal degradation of autophagosome contents in CoCl2-induced autophagy. We further identified that Rg3RGE-induced apoptotic cell death and autophagy inhibition was mediated by increased intracellular ROS levels. Similarly, in the in vivo xenograft model, Rg3RGE induced apoptosis and inhibited cell proliferation and autophagy.

Conclusion

Rg3RGE-stimulated ROS production promotes apoptosis and inhibits protective autophagy under hypoxic conditions. Autophagosome accumulation is critical to the apoptotic effects of Rg3RGE. The in vivo findings also demonstrate that Rg3RGE inhibits breast cancer cell growth, suggesting that Rg3RGE has potential as potential as a putative breast cancer therapeutic.

Human Chorionic Gonadotropin Regulates the Smad Signaling Pathway by Antagonizing TGF-β in Giant Cell Tumor of Bone

BACKGROUND

Giant cell tumor of bone (GCTB) is a locally aggressive bone tumour aggravated by stromal cell proliferation and metastasis.

OBJECTIVE

We investigated the mechanism of action of human chorionic gonadotropin (HCG) in mediating GCTB proliferation and invasion.

METHODS

The expression of HCG was quantified using quantitative real-time PCR. After the primary stromal cells were isolated and identified, the function of HCG in GCTB was estimated using the cell counting kit-8, flow cytometry, scratch experiment, transwell assay, Western blot, and immunofluorescence. Moreover, the mechanism of HCG was assessed through western blotting.

RESULTS

HCG expression was decreased in clinical tissue samples from patients with GCTB. We validated that HCG repressed stromal cell proliferation, migration, invasion, autophagy, and epithelial- mesenchymal transition (EMT) and promoted cell apoptosis in GCTB. We also verified that HCG repressed the autophagy and EMT of stromal cells through the Smad signaling axis in GCTB. HCG inhibited the transduction of the Smad signaling pathway by restraining the binding of the TGF-β II receptor to ligand Activin A.

CONCLUSION

HCG restrained the Smad signaling pathway by antagonizing TGF-β signaling in GCTB. HCG may serve as a useful patent to treat GCTB.

Improving targeted small molecule drugs to overcome chemotherapy resistance

BACKGROUND

Conventional cancer treatments face the challenge of therapeutic resistance, which causes poor treatment outcomes. The use of combination therapies can improve treatment results in patients and is one of the solutions to overcome this challenge. Chemotherapy is one of the conventional treatments that, due to the non-targeted and lack of specificity in targeting cancer cells, can cause serious complications in the short and long-term for patients by damaging healthy cells. Also, the employment of a wide range of strategies for chemotherapy resistance by cancer cells, metastasis, and cancer recurrence create serious problems to achieve the desired results of chemotherapy. Accordingly, targeted therapies can be used as a combination treatment with chemotherapy to both cause less damage to healthy cells, which as a result, they reduce the side effects of chemotherapy, and by targeting the factors that cause therapeutic challenges, can improve the results of chemotherapy in patients.

RECENT FINDINGS

Small molecules are one of the main targeted therapies that can be used for diverse targets in cancer treatment due to their penetration ability and characteristics. However, small molecules in cancer treatment are facing obstacles that a better understanding of cancer biology, as well as the mechanisms and factors involved in chemotherapy resistance, can lead to the improvement of this type of major targeted therapy.

CONCLUSION

In this review article, at first, the challenges that lead to not achieving the desired results in chemotherapy and how cancer cells can be resistant to chemotherapy are examined, and at the end, research areas are suggested that more focusing on them, can lead to the improvement of the results of using targeted small molecules as an adjunctive treatment for chemotherapy in the conditions of chemotherapy resistance and metastasis of cancer cells.

Hydroxychloroquine: Key therapeutic advances and emerging nanotechnological landscape for cancer mitigation

Hydroxychloroquine (HCQ) is a unique class of medications that has been widely utilized for the treatment of cancer. HCQ plays a dichotomous role by inhibiting autophagy induced by the tumor microenvironment (TME). Preclinical studies support the use of HCQ for anti-cancer therapy, especially in combination with conventional anti-cancer treatments since they sensitize tumor cells to drugs, potentiating the therapeutic activity. However, clinical evidence has suggested poor outcomes for HCQ due to various obstacles, including non-specific distribution, low aqueous solubility and low bioavailability at target sites, transport across tissue barriers, and retinal toxicity. These issues are addressable via the integration of HCQ with nanotechnology to produce HCQ-conjugated nanomedicines. This review aims to discuss the pharmacodynamic, pharmacokinetic and antitumor properties of HCQ. Furthermore, the antitumor performance of the nanoformulated HCQ is also reviewed thoroughly, aiming to serve as a guide for the HCQ-based enhanced treatment of cancers. The nanoencapsulation or nanoconjugation of HCQ with nanoassemblies appears to be a promising method for reducing the toxicity and improving the antitumor efficacy of HCQ.

Sennoside A induces autophagic death of prostate cancer via inactivation of PI3K/AKT/mTOR axis

Prostate cancer (PC) is the most common malignancy in male reproductive system. Sennoside A (SA) is an anthraquinone active ingredient extracted from Rheum officinale Baill., which exerts anti-tumor activity on different tumors. In the present study, the toxicity of SA on PC3 and DU 145 cells was detected via CCK-8. The effects of SA on growth, apoptosis, and autophagy were determined through CCK-8, Hoechst stain, flow cytometry, western blot, and immunofluorescence examinations. An in vivo experiment was performed in xenografted mice with intraperitoneal introduction of 10 mg/kg SA and validated via TUNEL, immunohistochemistry and western blot. The results showed that SA inhibited the cell viability with a IC50 value of 52.36 and 67.48 µM in DU 145 and PC3 cells respectively, and enhanced the apoptosis of PC3 and DU 145 cells. Additionally, SA elevated the relative LC3B expression, and the relative protein expression of LC3II/LC3I and Beclin-1, but diminished the P62 protein expression. The relative protein level of p-PI3K/PI3K, p-AKT/AKT and p-mTOR/mTOR was reduced with SA treatment, which was verified by the 740 Y-P application. The 740 Y-P treatments also restored the SA-induced the cell viability, apoptosis rate and relative LC3B expression. Meanwhile, SA inhibited the growth of PC cell and the relative protein level of PI3K/AKT/mTOR axis in vivo. Taken together, SA regulated the proliferation, apoptosis and autophagy via inactivating the PI3K/AKT/mTOR axis in PC.

Targeting autophagy and beyond: Deconvoluting the complexity of Beclin-1 from biological function to cancer therapy

Beclin-1 is the firstly-identified mammalian protein of the autophagy machinery, which functions as a molecular scaffold for the assembly of PI3KC3 (class III phosphatidylinositol 3 kinase) complex, thus controlling autophagy induction and other cellular trafficking events. Notably, there is mounting evidence establishing the implications of Beclin-1 in diverse tumorigenesis processes, including tumor suppression and progression as well as resistance to cancer therapeutics and CSC (cancer stem-like cell) maintenance. More importantly, Beclin-1 has been confirmed as a potential target for the treatment of multiple cancers. In this review, we provide a comprehensive survey of the structure, functions, and regulations of Beclin-1, and we discuss recent advances in understanding the controversial roles of Beclin-1 in oncology. Moreover, we focus on summarizing the targeted Beclin-1-regulating strategies in cancer therapy, providing novel insights into a promising strategy for regulating Beclin-1 to improve cancer therapeutics in the future.

The role of HMGB1 in digestive cancer

High mobility group box protein B1 (HMGB1) belongs to the HMG family, is widely expressed in the nucleus of digestive mucosal epithelial cells, mesenchymal cells and immune cells, and binds to DNA to participate in genomic structural stability, mismatch repair and transcriptional regulation to maintain normal cellular activities. In the context of digestive inflammation and tumors, HMGB1 readily migrates into the extracellular matrix and binds to immune cell receptors to affect their function and differentiation, further promoting digestive tract tissue injury and tumor development. Notably, HMGB1 can also promote the antitumor immune response. Therefore, these seemingly opposing effects in tumors make targeted HMGB1 therapies important in digestive cancer. This review focuses on the role of HMGB1 in tumors and its effects on key pathways of digestive cancer and aims to provide new possibilities for targeted tumor therapy.

Dissecting the Role of Autophagy-Related Proteins in Cancer Metabolism and Plasticity

Modulation of autophagy as an anticancer strategy has been widely studied and evaluated in several cell models. However, little attention has been paid to the metabolic changes that occur in a cancer cell when autophagy is inhibited or induced. In this review, we describe how the expression and regulation of various autophagy-related (ATGs) genes and proteins are associated with cancer progression and cancer plasticity. We present a comprehensive review of how deregulation of ATGs affects cancer cell metabolism, where inhibition of autophagy is mainly reflected in the enhancement of the Warburg effect. The importance of metabolic changes, which largely depend on the cancer type and form part of a cancer cell's escape strategy after autophagy modulation, is emphasized. Consequently, pharmacological strategies based on a dual inhibition of metabolic and autophagy pathways emerged and are reviewed critically here.

Research on the role of cellular autophagy in the sensitivity of human tongue cancer cells to radiotherapy and chemotherapy

OBJECTIVE

This paper aims to investigate the role of cisplatin-induced autophagy in human tongue squamous carcinoma Tca8113 cells.

METHODS

After inhibiting the expression of autophagic proteins with different autophagy inhibitors (3-methyladenine, chloroquine), the sensitivity of human tongue squamous cell carcinoma (Tca8113) cells to killing by gradient concentrations of cisplatin and gradient doses of radiation was detected using a colony formation assay. Further, the changes of autophagy expression in Tca8113 cells that had been treated with cisplatin and radiation were detected using western immunoblot, GFP-LC3 fluorescence and transmission electron microscopy.

RESULTS

The sensitivity of Tca8113 cells to cisplatin and radiation was significantly increased (P < 0.05) after reducing autophagy expression using different autophagy inhibitors. Meanwhile, the expression of autophagy in the cells was significantly increased by cisplatin and radiation treatment.

CONCLUSION

Tca8113 cells upregulated autophagy under the effect of either radiation or cisplatin, and the sensitivity of Tca8113 cells to cisplatin and radiation could be improved by inhibiting autophagy using multiple pathways.

Proliferation and migration of ML1 follicular thyroid cancer cells are inhibited by IU1 targeting USP14: role of proteasome and autophagy flux

USP14 is a deubiquitinating enzyme involved in protein degradation by interacting with the proteasome and removal of poly-ubiquitin chains on target proteins. USP14 can influence cellular processes such as cell survival, DNA repair, ER stress, endocytosis, and the inflammatory response. USP14 further plays a role in tumor growth, and the inhibition of USP14 by compounds such as IU1 may affect cancer cell migration and invasion. Here we have studied the mechanisms for the action of IU1 in ML1 follicular thyroid cancer cells, comparing them with control, primary thyroid cells. Treatment with IU1 reduced proliferation of ML1 cells in a concentration-dependent manner, and more prominently than in control cells. IU1 decreased basal migration of ML1 cells, and after stimulation of cells with the bioactive compound, sphingosine-1-phosphate. The sphingosine-1-phosphate receptor 3 was increased in ML1 cells as compared with control thyroid cells, but this was not influenced by IU1. Further studies on the mechanism, revealed that IU1 enhanced the proteasome activity as well as LC3B-dependent autophagy flux in ML1 cells with an opposite effect on control thyroid cells. This indicates that IU1 elicits a cell-type dependent autophagy response, increasing it in ML1 cancer cells. The IU1-mediated stimulation of autophagy and proteasomes can likely contribute to the reduced cell proliferation and migration observed in ML1 cells. The precise set of proteins affected by IU1 in ML1 thyroid and other cancer cells warrant further investigations.

Galectin-9 has non-apoptotic cytotoxic activity toward acute myeloid leukemia independent of cytarabine resistance

Acute myeloid leukemia (AML) is a malignancy still associated with poor survival rates, among others, due to frequent occurrence of therapy-resistant relapse after standard-of-care treatment with cytarabine (AraC). AraC triggers apoptotic cell death, a type of cell death to which AML cells often become resistant. Therefore, therapeutic options that trigger an alternate type of cell death are of particular interest. We previously identified that the glycan-binding protein Galectin-9 (Gal-9) has tumor-selective and non-apoptotic cytotoxicity towards various types of cancer, which depended on autophagy inhibition. Thus, Gal-9 could be of therapeutic interest for (AraC-resistant) AML. In the current study, treatment with Gal-9 was cytotoxic for AML cells, including for CD34⁺ patient-derived AML stem cells, but not for healthy cord blood-derived CD34⁺ stem cells. This Gal-9-mediated cytotoxicity did not rely on apoptosis but was negatively associated with autophagic flux. Importantly, both AraC-sensitive and -resistant AML cell lines, as well as AML patient samples, were sensitive to single-agent treatment with Gal-9. Additionally, Gal-9 potentiated the cytotoxic effect of DNA demethylase inhibitor Azacytidine (Aza), a drug that is clinically used for patients that are not eligible for intensive AraC treatment. Thus, Gal-9 is a potential therapeutic agent for the treatment of AML, including AraC-resistant AML, by inducing caspase-independent cell death.

Advances in Understanding the Links between Metabolism and Autophagy in Acute Myeloid Leukemia: From Biology to Therapeutic Targeting

Autophagy is a highly conserved cellular degradation process that regulates cellular metabolism and homeostasis under normal and pathophysiological conditions. Autophagy and metabolism are linked in the hematopoietic system, playing a fundamental role in the self-renewal, survival, and differentiation of hematopoietic stem and progenitor cells, and in cell death, particularly affecting the cellular fate of the hematopoietic stem cell pool. In leukemia, autophagy sustains leukemic cell growth, contributes to survival of leukemic stem cells and chemotherapy resistance. The high frequency of disease relapse caused by relapse-initiating leukemic cells resistant to therapy occurs in acute myeloid leukemia (AML), and depends on the AML subtypes and treatments used. Targeting autophagy may represent a promising strategy to overcome therapeutic resistance in AML, for which prognosis remains poor. In this review, we illustrate the role of autophagy and the impact of its deregulation on the metabolism of normal and leukemic hematopoietic cells. We report updates on the contribution of autophagy to AML development and relapse, and the latest evidence indicating autophagy-related genes as potential prognostic predictors and drivers of AML. We review the recent advances in autophagy manipulation, combined with various anti-leukemia therapies, for an effective autophagy-targeted therapy for AML.

Role of autophagy and its regulation by noncoding RNAs in ovarian cancer

Autophagy is a self-digestion process by which misfolded proteins and damaged organelles in eukaryotic cells are degraded to maintain cellular homeostasis. This process is involved in the tumorigenesis, metastasis, and chemoresistance of various tumors such as ovarian cancer (OC). Noncoding RNAs (ncRNAs), mainly including microRNAs, long noncoding RNAs, and circular RNAs, have been extensively investigated in cancer research for their roles in the regulation of autophagy. Recent studies have shown that in OC cells, ncRNAs can modulate the formation of autophagosomes, which affect tumor progression and chemoresistance. An understanding of the role of autophagy in OC progression, treatment, and prognosis is important, and the identification of the regulatory roles of ncRNAs in autophagy leads to intervention strategies for OC therapy. This review summarizes the role of autophagy in OC and discusses the role of ncRNA-mediated autophagy in OC, as an understanding of these roles may contribute to the development of potential therapeutic strategies for this disease.

Palbociclib-Induced Cellular Senescence Is Modulated by the mTOR Complex 1 and Autophagy

Despite not dividing, senescent cells acquire the ability to synthesize and secrete a plethora of bioactive molecules, a feature known as the senescence-associated secretory phenotype (SASP). In addition, senescent cells often upregulate autophagy, a catalytic process that improves cell viability in stress-challenged cells. Notably, this "senescence-related autophagy" can provide free amino acids for the activation of mTORC1 and the synthesis of SASP components. However, little is known about the functional status of mTORC1 in models of senescence induced by CDK4/6 inhibitors (e.g., Palbociclib), or the effects that the inhibition of mTORC1 or the combined inhibition of mTORC1 and autophagy have on senescence and the SASP. Herein, we examined the effects of mTORC1 inhibition, with or without concomitant autophagy inhibition, on Palbociclib-driven senescent AGS and MCF-7 cells. We also assessed the pro-tumorigenic effects of conditioned media from Palbociclib-driven senescent cells with the inhibition of mTORC1, or with the combined inhibition of mTORC1 and autophagy. We found that Palbociclib-driven senescent cells display a partially reduced activity of mTORC1 accompanied by increased levels of autophagy. Interestingly, further mTORC1 inhibition exacerbated the senescent phenotype, a phenomenon that was reversed upon autophagy inhibition. Finally, the SASP varied upon inhibiting mTORC1, or upon the combined inhibition of mTORC1 and autophagy, generating diverse responses in cell proliferation, invasion, and migration of non-senescent tumorigenic cells. Overall, variations in the SASP of Palbociclib-driven senescent cells with the concomitant inhibition of mTORC1 seem to depend on autophagy.

The "Self-eating" of cancer-associated fibroblast: A potential target for cancer

Autophagy helps maintain energy homeostasis and protect cells from stress effects by selectively removing misfolded/polyubiquitylated proteins, lipids, and damaged mitochondria. Cancer-associated fibroblasts (CAFs) are cellular components of tumor microenvironment (TME). Autophagy in CAFs inhibits tumor development in the early stages; however, it has a tumor-promoting effect in advanced stages. In this review, we aimed to summarize the modulators responsible for the induction of autophagy in CAFs, such as hypoxia, nutrient deprivation, mitochondrial stress, and endoplasmic reticulum stress. In addition, we aimed to present autophagy-related signaling pathways in CAFs, and role of autophagy in CAF activation, tumor progression, tumor immune microenvironment. Autophagy in CAFs may be an emerging target for tumor therapy. In summary, autophagy in CAFs is regulated by a variety of modulators and can reshape tumor immune microenvironment, affecting tumor progression and treatment.

Short peptide domains of the Wnt inhibitor sFRP4 target ovarian cancer stem cells by neutralizing the Wnt β-catenin pathway, disrupting the interaction between β-catenin and CD24 and suppressing autophagy

AIMS

One of the hallmarks of cancer stem cells (CSC) is hyperactive Wnt β-catenin signaling due to the decreased presence of Wnt antagonists such as secreted frizzled related protein 4 (SFRP4). Cysteine-rich domain (CRD) and netrin-like domain (NLD) are the two functional domains of SFRP4 having anti-tumor properties. In this study, we have explored the effectiveness of short micropeptides SC-301 (from CRD) and SC-401 (from NLD) on CSC properties, EMT, apoptosis and autophagy in ovarian CSCs enriched from PA-1 and SKOV-3 cell lines.

MAIN METHODS

Gene expression analysis, Western blot and immunocytochemistry were performed on ovarian CSCs to evaluate the inhibitory potential of micropeptides to various CSC associated oncogenic properties. Co-immunoprecipitation was performed to detect the binding of CD24 to β-catenin protein complex. CYTO-ID Autophagy Detection Kit 2.0 was used to monitor autophagic flux in peptide treated CSCs.

KEY FINDINGS

It is clearly seen that the micropeptides derived from both the domains inhibit Wnt pathway, initiate apoptosis, inhibit migration and chemosensitize CSCs. Specifically, CD24, a defining marker of ovarian CSC was suppressed by peptide treatment. Notably, interaction between CD24 and β-catenin was disrupted upon peptide treatment. SFRP4 peptide treatment also suppressed the autophagic process which is crucial for CSC survival.

SIGNIFICANCE

The study demonstrated that although both peptides have inhibitory effects, SC-401 was emphatically more effective in targeting CSC properties and down regulating the Wnt β-catenin machinery.

Exploring the Complex Link between Autophagy, Regulated Cell Death, and Cell Fate Pathways in Cancer Pathogenesis and Therapy

Autophagy is a catabolic lysosomal-dependent pathway involved in the degradation of cellular materials, supplying precursor compounds and energy for macromolecule synthesis and metabolic needs [...].

FOXP3 and SQSTM1/P62 correlate with prognosis and immune infiltration in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common highly malignant tumours worldwide. FOXP3 and SQSTM1/P62 have been shown to be abnormally expressed in tumour cells, but their function in different tumours remains controversial. The present study was designed to evaluate the expression of FOXP3 and P62 in HCC and their prognostic value as well as their relationship with immune infiltration in HCC patients.

METHODS

The Gene Expression Omnibus (GEO) database and TNMplot.com platform were used to analyse the expression of FOXP3 and P62. The Cancer Genome Atlas (TCGA) database and Kaplan-Meier plotter were used to assess the impacts of FOXP3 and P62 on clinical prognosis. In addition, TCGA database was also used to examine the correlation between the expression of FOXP3 and P62 and tumour immune infiltration using the CIBERSORT algorithm. Finally, immunohistochemistry (IHC) was used to determine expression levels of FOXP3 and P62 in 89 HCC and adjacent normal liver tissues, and their effects on clinicopathological features and prognosis were verified.

RESULTS

FOXP3 expression was downregulated in HCC tissues, while P62 expression was upregulated. FOXP3 underexpression and P62 overexpression were closely related to decreased overall survival (OS) in HCC patients. Additionally, the abnormal expression of FOXP3 and P62 was closely related to the infiltration levels of 12 types of immune cells, including regulatory T cells (Tregs), M2 macrophages, M0 macrophages, and CD8 T cells. Notably, in the validation model, abnormal FOXP3 and P62 expression was significantly associated with adverse clinicopathological factors in HCC patients, including elevated α-fetoprotein (AFP) levels, poor tumour differentiation, and increased Ki67 levels. Furthermore, low FOXP3 and high P62 expression were independent risk factors for predicting OS prognosis in HCC patients.

CONCLUSION

FOXP3 and P62 have been shown to be important prognostic factors in HCC patients and are associated with immune cell infiltration in HCC. These findings suggest that FOXP3 and P62 may be valuable prognostic biomarkers and potential therapeutic targets for HCC treatment.

Construction and validation of a bladder cancer risk model based on autophagy-related genes

Autophagy has an important association with tumorigenesis, progression, and prognosis. However, the mechanism of autophagy-regulated genes on the risk prognosis of bladder cancer (BC) patients has not been fully elucidated yet. In this study, we created a prognostic model of BC risk based on autophagy-related genes, which further illustrates the value of genes associated with autophagy in the treatment of BC. We first downloaded human autophagy-associated genes and BC datasets from Human Autophagy Database and The Cancer Genome Atlas (TCGA) database, and finally obtained differential prognosis-associated genes for autophagy by univariate regression analysis and differential analysis of cancer versus normal tissues. Subsequently, we downloaded two datasets from Gene Expression Omnibus (GEO), GSE31684 and GSE15307, to expand the total number of samples. Based on these genes, we distinguished the molecular subtypes (C1, C2) and gene classes (A, B) of BC by consistent clustering analysis. Using the genes merged from TCGA and the two GEO datasets, we conducted least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analysis to obtain risk genes and construct autophagy-related risk prediction models. The accuracy of this risk prediction model was assessed by receiver operating characteristic (ROC) and calibration curves, and then nomograms were constructed to predict the survival of bladder cancer patients at 1, 3, and 5 years, respectively. According to the median value of the risk score, we divided BC samples into the high- and low-risk groups. Kaplan-Meier (K-M) survival analysis was performed to compare survival differences between subgroups. Then, we used single sample gene set enrichment analysis (ssGSEA) for immune cell infiltration abundance, immune checkpoint genes, immunotherapy response, gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis, and tumor mutation burden (TMB) analysis for different subgroups. We also applied quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry (IHC) techniques to verify the expression of these six genes in the model. Finally, we chose the IMvigor210 dataset for external validation. Six risk genes associated with autophagy (SPOCD1, FKBP10, NAT8B, LDLR, STMN3, and ANXA2) were finally screened by LASSO regression algorithm and multivariate Cox regression analysis. ROC and calibration curves showed that the model established was accurate and reliable. Univariate and multivariate regression analyses were used to verify that the risk model was an independent predictor. K-M survival analysis indicated that patients in the high-risk group had significantly worse overall survival than those in the low-risk group. Analysis by algorithms such as correlation analysis, gene set variation analysis (GSVA), and ssGSEA showed that differences in immune microenvironment, enrichment of multiple biologically active pathways, TMB, immune checkpoint genes, and human leukocyte antigens (HLAs) were observed in the different risk groups. Then, we constructed nomograms that predicted the 1-, 3-, and 5-year survival rates of different BC patients. In addition, we screened nine sensitive chemotherapeutic drugs using the correlation between the obtained expression status of risk genes and drug sensitivity results. Finally, the external dataset IMvigor210 verified that the model is reliable and efficient. We established an autophagy-related risk prognostic model that is accurate and reliable, which lays the foundation for future personalized treatment of bladder cancer.

A novel autophagy-related long non-coding RNAs prognostic risk score for clear cell renal cell carcinoma

BACKGROUND

As the main histological subtype of renal cell carcinoma, clear cell renal cell carcinoma (ccRCC) places a heavy burden on health worldwide. Autophagy-related long non-coding RNAs (ARlncRs) have shown tremendous potential as prognostic signatures in several studies, but the relationship between them and ccRCC still has to be demonstrated.

METHODS

The RNA-sequencing and clinical characteristics of 483 ccRCC patients were downloaded download from the Cancer Genome Atlas and International Cancer Genome Consortium. ARlncRs were determined by Pearson correlation analysis. Univariate and multivariate Cox regression analyses were applied to establish a risk score model. A nomogram was constructed considering independent prognostic factors. The Harrell concordance index calibration curve and the receiver operating characteristic analysis were utilized to evaluate the nomogram. Furthermore, functional enrichment analysis was used for differentially expressed genes between the two groups of high- and low-risk scores.

RESULTS

A total of 9 SARlncRs were established as a risk score model. The Kaplan-Meier survival curve, principal component analysis, and subgroup analysis showed that low overall survival of patients was associated with high-risk scores. Age, M stage, and risk score were identified as independent prognostic factors to establish a nomogram, whose concordance index in the training cohort, internal validation, and external ICGC cohort was 0.793, 0.671, and 0.668 respectively. The area under the curve for 5-year OS prediction in the training cohort, internal validation, and external ICGC cohort was 0.840, 0.706, and 0.708, respectively. GO analysis and KEGG analysis of DEGs demonstrated that immune- and inflammatory-related pathways are likely to be critically involved in the progress of ccRCC.

CONCLUSIONS

We established and validated a novel ARlncRs prognostic risk model which is valuable as a potential therapeutic target and prognosis indicator for ccRCC. A nomogram including the risk model is a promising clinical tool for outcomes prediction of ccRCC patients and further formulation of individualized strategy.

Significance of exosomes in hepatocellular carcinoma

Among the most prevalent cancers in the world, hepatocellular carcinoma (HCC) has a high mortality rate. The diagnosis and management of HCC are presently hindered by difficulties in early detection and suboptimal treatment outcomes. Exosomes have been shown to play an important role in hepatocarcinogenesis and can also be used for diagnosis and treatment. In this review, we discussed the research progress on exosomes in hepatocarcinogenesis development, tumor microenvironment remodeling, treatment resistance, and immunosuppression. HCC can be diagnosed and treated by understanding the pathogenesis and identifying early diagnostic markers. This review will be a significant reference for scholars with an initial understanding of the field to fully understand the role of exosomes in the organism.

BNIP3 enhances pancreatic cancer cell migration and proliferation via modulating autophagy under hypoxia

Chemotherapy and immunotherapy for pancreatic ductal adenocarcinoma (PDAC) have limited success for the intricated surrounding cancer microenvironment. Hypoxic microenvironment in PDAC causes the activation of multiple different molecules and signaling pathways compared with normoxia. We studied the roles of BNIP3 for the migration and proliferation of PDAC and Panc1 cells in vitro. In the present study, we found that BNIP3 expression was elevated and enhanced the migration and proliferation of CFPAC-1 and Panc1 cells under hypoxia. The upregulation of BNIP3 was important for the autophagic activation, while inhibition of autophagy with siRNA targeting Atg5 and Atg7 impaired the hypoxia-induced cell migration and proliferation. Additionally, blocking ERK1/2 mitogen-activated protein kinase (MAPK) signaling with PD98058 significantly down-regulated BNIP3 expression, autophagic activation, as well as the migration and proliferation of CFPAC-1 and Panc1 cells under hypoxia. Collectively, our results here uncover a hitherto unknown hypoxia-BNIP3-autophagy axis in modulating the migration and proliferation and provide a potential intriguing drug target for the therapy of PDAC.

The role of autophagy in colorectal cancer: Impact on pathogenesis and implications in therapy

Colorectal cancer (CRC) is considered as a global major cause of cancer death. Surgical resection is the main line of treatment; however, chemo-, radiotherapy and other adjuvant agents are crucial to achieve good outcomes. The tumor microenvironment (TME) is a well-recognized key player in CRC progression, yet the processes linking the cancer cells to its TME are not fully delineated. Autophagy is one of such processes, with a controversial role in the pathogenesis of CRC, with its intricate links to many pathological factors and processes. Autophagy may apparently play conflicting roles in carcinogenesis, but the precise mechanisms determining the overall direction of the process seem to depend on the context. Additionally, it has been established that autophagy has a remarkable effect on the endothelial cells in the TME, the key substrate for angiogenesis that supports tumor metastasis. Favorable response to immunotherapy occurs only in a specific subpopulation of CRC patients, namely the microsatellite instability-high (MSI-H). In view of such limitations of immunotherapy in CRC, modulation of autophagy represents a potential adjuvant strategy to enhance the effect of those relatively safe agents on wider CRC molecular subtypes. In this review, we discussed the molecular control of autophagy in CRC and how autophagy affects different processes and mechanisms that shape the TME. We explored how autophagy contributes to CRC initiation and progression, and how it interacts with tumor immunity, hypoxia, and oxidative stress. The crosstalk between autophagy and the TME in CRC was extensively dissected. Finally, we reported the clinical efforts and challenges in combining autophagy modulators with various cancer-targeted agents to improve CRC patients’ survival and restrain cancer growth.

All-trans retinoic acid-mediated miR-30a up-regulation suppresses autophagy and sensitizes gastric cancer cells to cisplatin

AIMS

The potential of all-trans retinoic acid (ATRA) in regulating some microRNAs (miRNAs) involved in multiple cancer-related pathways, including resistance to chemotherapeutics, may be a valuable idea for overcoming the CDDP resistance of GC cells.

MAIN METHODS

Treatment of gastric AGS and MKN-45 cells with CDDP enriched the CDDP surviving cells (CDDP-SCs). The abilities of chemoresistance to CDDP drug, migration, either apoptosis or cell cycle distribution, spheroid body formation and changes at miRNA and protein levels were evaluated in vitro by MTT assay, colony formation assay, flow cytometry, tumor spheres culture, qRT-PCR and western blot assay in CDDP-SCs and ATRA-treated CDDP-SCs cells, respectively.

KEY FINDINGS

CDDP-based chemotherapy significantly reduced microRNA-30a (miR-30a) levels in GC cells. We also observed elevated autophagy activity in cancer cells that possess stem cell-like properties with overexpressed specific stem cell markers. Our extended study suggested that the reduction of miR-30a by CDDP treatment, is the possible underlying mechanism of enhanced autophagic activity, as demonstrated by enhancing autophagy-related protein beclin 1 and LC3-II/LC-I ratio. The addition of ATRA in the culture medium of GC cells increased the expression of miR-30a, and disturbed characteristic CSC-like properties. Additional studies revealed that the increased expression of miR-30a declined the expression level of its target gene, beclin 1, and beclin 1-mediated autophagy. This leads to promoted CDDP-induced GC cell apoptosis and G2/M cell cycle arrest.

SIGNIFICANCE

Overall, miR-30a/autophagy signaling has a critical role in regulating the chemoresistance of GC cells that ATRA could modulate.

Downregulation of fibulin-4 inhibits autophagy and promotes the sensitivity of esophageal squamous cell carcinoma cells to apatinib by activating the Akt-mTOR signaling pathway

Background

Fibulin‐4, namely, EFEMP2, is an essential matricellular protein associated with a variety of malignancies. The aim of this study was to explore the role of fibulin‐4 in the progression of esophageal squamous cell carcinoma (ESCC), as well as its effect on ESCC sensitivity to apatinib treatment.

Methods

The expression of fibulin‐4 in ESCC tissues and cell lines was detected. Stably transfected ESCC cells were established by transducing lentiviral vectors for silencing or overexpressing the fibulin‐4 gene into ESCC cells, and a subcutaneous xenograft tumor model of ESCC in mice was successfully established. IHC, RT–qPCR and western blotting were used to detect the expression of related genes and proteins. The CCK8 assay, EdU cell proliferation assay, wound healing assay, transwell assay and flow cytometry were used to evaluate the proliferation, invasion, migration and apoptosis of ESCC cells. After mice were sacrificed, the transplanted tumors were resected, and their volumes were measured.

Results

The expression of fibulin‐4 was significantly increased in both ESCC tissues and cell lines, and the high expression was closely related to the poor clinicopathological features. Downregulation of fibulin‐4 inhibited the proliferation, invasion and migration of ESCC cells in vitro and in vivo. Meanwhile, fibulin‐4 knockdown inhibited autophagy of tumor cells by activating the Akt–mTOR signaling pathway and significantly promoted apatinib‐induced apoptosis of ESCC cells.

Conclusion

Our study showed that fibulin‐4 is an oncogene that can promote ESCC progression and inhibit apoptosis. Downregulation of fibulin‐4 enhances the sensitivity of ESCC cells to apatinib by inhibiting cellular protective autophagy through activating the Akt–mTOR signaling pathway.

Inhibiting Cytoprotective Autophagy in Cancer Therapy: An Update on Pharmacological Small-Molecule Compounds

Autophagy is a self-degradation process in which damaged proteins and organelles are engulfed into autophagosomes for digestion and eventually recycled for cellular metabolism to maintain intracellular homeostasis. Accumulating studies have reported that autophagy has the Janus role in cancer as a tumor suppressor or an oncogenic role to promote the growth of established tumors and developing drug resistance. Importantly, cytoprotective autophagy plays a prominent role in many types of human cancers, thus inhibiting autophagy, and has been regarded as a promising therapeutic strategy for cancer therapy. Here, we focus on summarizing small-molecule compounds inhibiting the autophagy process, as well as further discuss other dual-target small-molecule compounds, combination strategies, and other strategies to improve potential cancer therapy. Therefore, these findings will shed new light on exploiting more small-molecule compounds inhibiting cytoprotective autophagy as candidate drugs for fighting human cancers in the future.

Glutamine is essential for overcoming the immunosuppressive microenvironment in malignant salivary gland tumors

Rationale: Immunosuppression in the tumor microenvironment (TME) is key to the pathogenesis of solid tumors. Tumor cell-intrinsic autophagy is critical for sustaining both tumor cell metabolism and survival. However, the role of autophagy in the host immune system that allows cancer cells to escape immune destruction remains poorly understood. Here, we determined if attenuated host autophagy is sufficient to induce tumor rejection through reinforced adaptive immunity. Furthermore, we determined whether dietary glutamine supplementation, mimicking attenuated host autophagy, is capable of promoting antitumor immunity. Methods: A syngeneic orthotopic tumor model in Atg5+/+ and Atg5flox/flox mice was established to determine the impact of host autophagy on the antitumor effects against mouse malignant salivary gland tumors (MSTs). Multiple cohorts of immunocompetent mice were used for oncoimmunology studies, including inflammatory cytokine levels, macrophage, CD4+, and CD8+ cells tumor infiltration at 14 days and 28 days after MST inoculation. In vitro differentiation and in vivo dietary glutamine supplementation were used to assess the effects of glutamine on Treg differentiation and tumor expansion. Results: We showed that mice deficient in the essential autophagy gene, Atg5, rejected orthotopic allografts of isogenic MST cells. An enhanced antitumor immune response evidenced by reduction of both M1 and M2 macrophages, increased infiltration of CD8+ T cells, elevated IFN-γ production, as well as decreased inhibitory Tregs within TME and spleens of tumor-bearing Atg5flox/flox mice. Mechanistically, ATG5 deficiency increased glutamine level in tumors. We further demonstrated that dietary glutamine supplementation partially increased glutamine levels and restored potent antitumor responses in Atg5+/+ mice. Conclusions: Dietary glutamine supplementation exposes a previously undefined difference in plasticity between cancer cells, cytotoxic CD8+ T cells and Tregs.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Autophagy: A Key Player in Pancreatic Cancer Progression and a Potential Drug Target

Simple Summary

With the mortality rate of pancreatic cancer predicted to rise over the coming years, it is essential that effective treatment strategies are developed as soon as possible. Pancreatic cancer has always proven very difficult to treat due to its fast growing and aggressive nature. Chemotherapeutic treatment has struggled to increase the survival rate of pancreatic cancer patients due to effective chemo-resistant properties that derive from the supporting tumor microenvironment and autophagy, a vital survival pathway. This review will explore how the autophagy pathway and tumor microenvironment help to sustain tumor survival under stress and expand into a metastatic state. Due to the comprehensive understanding of the autophagy pathway, we will highlight the potential chinks in the pancreatic tumor’s armor and identify potential targets to overcome chemo-resistance in pancreatic cancer. We will also present novel autophagy inhibitors that could reduce tumor survival and how they could be most effectively conceived.

Abstract

Pancreatic cancer is known to have the lowest survival outcomes among all major cancers, and unfortunately, this has only been marginally improved over last four decades. The innate characteristics of pancreatic cancer include an aggressive and fast-growing nature from powerful driver mutations, a highly defensive tumor microenvironment and the upregulation of advantageous survival pathways such as autophagy. Autophagy involves targeted degradation of proteins and organelles to provide a secondary source of cellular supplies to maintain cell growth. Elevated autophagic activity in pancreatic cancer is recognized as a major survival pathway as it provides a plethora of support for tumors by supplying vital resources, maintaining tumour survival under the stressful microenvironment and promoting other pathways involved in tumour progression and metastasis. The combination of these features is unique to pancreatic cancer and present significant resistance to chemotherapeutic strategies, thus, indicating a need for further investigation into therapies targeting this crucial pathway. This review will outline the autophagy pathway and its regulation, in addition to the genetic landscape and tumor microenvironment that contribute to pancreatic cancer severity. Moreover, this review will also discuss the mechanisms of novel therapeutic strategies that inhibit autophagy and how they could be used to suppress tumor progression.

Bioinformatics Analysis Reveals an Association between Autophagy, Prognosis, Tumor Microenvironment, and Immunotherapy in Osteosarcoma

Autophagy is a catabolic pathway involved in the regulation of bone homeostasis. We explore clinical correlation of autophagy-related key molecules to establish risk signature for predicting the prognosis, tumor microenvironment (TME), and immunotherapy response of osteosarcoma. Single cell RNA sequencing data from GSE162454 dataset distinguished malignant cells from normal cells in osteosarcoma. Autophagy-related genes (ARGs) were extracted from the established risk signature of the Molecular Signatures Database of Gene Set Enrichment Analysis (GSEA) by univariate Cox and least absolute shrinkage and selection operator (LASSO) Cox regression analysis. Overall survival (OS), TME score, abundance of infiltrating immune cells, and response to immune-checkpoint blockade (ICB) treatment in patients with different risks were compared based on risk score. Nine ARGs were identified and risk signature was constructed. In all osteosarcoma datasets, the OS was significantly longer in the high-risk patients than low-risk onset. Risk signature significantly stratified clinical outcomes, including OS, metastatic status, and survival status. Risk signature was an independent variable for predicting osteosarcoma OS and showed high accuracy. A nomogram based on risk signature and metastases was developed. The calibration curve confirmed the consistency in 1-year, 3-year, and 5-year predicted OS and the actual OS. The risk score was related to 6 kinds of T cells and macrophages, myeloid-derived suppressor cell, natural killer cell, immune score, and stromal score in TME. The risk signature helped in predicting patients' response to anti-PD1/anti-PD-L1 treatment. The ARGs-led risk signature has important value for survival prediction, risk stratification, tumor microenvironment, and immune response evaluation of osteosarcoma.

Hepatocellular Carcinoma Intrinsic Cell Death Regulates Immune Response and Prognosis

Ablative and locoregional treatment options, such as radiofrequency, ethanol injection, microwave, and cryoablation, as well as irreversible electroporation, are effective therapies for early-stage hepatocellular carcinoma (HCC). Hepatocyte death caused by ablative procedures is known to increase the release of tumor-associated antigen, thus enhancing tumor immunogenicity. In addition, the heat ablative resection induces pyroptotic cell death accompanied by the release of several inflammatory factors and immune-related proteins, including damage-associated molecular patterns (DAMPs), heat shock proteins (HSPs), ficolin 3, ATP, and DNA/RNA, which potentiate the antitumoral immune response. Surgical approaches that enhance tumor necrosis and reduce hypoxia in the residual liver parenchyma have been shown to increase the disease-free survival rate by reducing the host’s immunosuppressive response. Scalpel devices and targeted surgical approach combined with immune-modulating drugs are an interesting and promising area to maximize therapeutic outcomes after HCC ablation.

Research Progress of Long Non-Coding RNA GAS5 in Malignant Tumors

With completing the whole genome sequencing project, awareness of lncRNA further deepened. The growth arrest-specific transcript 5 (GAS5) was initially identified in growth-inhibiting cells. GAS5 is a lncRNA (long non-coding RNA), and it plays a crucial role in various human cancers. There are small ORFs (open reading frames) in the exons of the GAS5 gene sequence, but they do not encode functional proteins. In addition, GAS5 is also the host gene of several small nucleolar RNAs (snoRNA). These snoRNAs are believed to play a suppressive role during tumor progression by methylating ribosomal RNA (rRNA). As a result, GAS5 expression levels in tumor tissues are significantly reduced, leading to increased malignancy, poor prognosis, and drug resistance. Recent studies have demonstrated that GAS5 can interact with miRNAs by base-pairing and other functional proteins to inhibit their biological functions, impacting signaling pathways and changing the level of intracellular autophagy, oxidative stress, and immune cell function in vivo. In addition, GAS5 participates in regulating proliferation, invasion, and apoptosis through the above molecular mechanisms. This article reviews the recent discoveries on GAS5, including its expression levels in different tumors, its biological behavior, and its molecular regulation mechanism in human cancers. The value of GAS5 as a molecular marker in the prevention and treatment of cancers is also discussed.

Oleanolic acid induces HCT116 colon cancer cell death through the p38/FOXO3a/Sirt6 pathway

Oleanolic acid (OA) is a natural compound that possesses numerous beneficial health effects, including anticancer activity. The current study aimed to investigate the role of forkhead box O3a (FOXO3a) in autophagy/mitophagy by OA in HCT116 cell line. OA dose-dependently reduced viability of HCT116 cells, with IC₅₀ = 29.8 μΜ. The expression of cleaved caspase-3 and poly (ADP-ribose) polymerase 1 increased after OA treatment, suggesting induction of apoptosis. Concurrently, OA induced autophagy, evidenced by increased expression of Beclin-1, autophagy-related protein 5 and microtubule-associated protein1A/1B-light chain 3 beta (LC3B), which played a prosurvival role. The induction of mitophagy was suggested by increased expression of p62 and PTEN-induced kinase 1 and reduced expression of translocase of outer mitochondrial membrane 20, which colocalized with LC3B. OA also induced nuclear accumulation of forkhead box O3a (FOXO3a). The cytotoxic activity of OA coincided with upregulation of p38. Inhibition of p38 led to increase in FOXO3a and NAD⁺-dependent deacetylase sirtuin 6 expression. In vivo, OA inhibited tumor growth in colon cancer xenograft mice. Our results suggest concomitant induction of apoptosis and prosurvival mitophagy by OA in colon cancer via p38/FOXO3a/Sirt6 signaling. Additionally, our data demonstrate that OA can chemosensitize colon cancer cells to 5-fluorouracil (5-FU).

Evaluation of targeting autophagy for the treatment of malignant rhabdoid tumours

Malignant rhabdoid tumour (MRT) is a rare and aggressive paediatric tumour that typically arises in the kidneys or central nervous system (CNS). The malignancy often affects patients under the age of three and is associated with an extremely poor survival rate, with most deaths occurring within the first year of presentation. Thus, there is an unmet and urgent medical need for novel therapeutic strategies for this malignancy. One of the major issues when treating MRT patients is the emergence of chemoresistance. Autophagy has become an area of focus in the study of chemoresistance due to its reported dual role as both a pro-survival and pro-death mechanism. The role of autophagy in the chemotherapeutic response of MRT remains largely unknown. A greater understanding of the role of autophagy may lead to the development of therapeutic strategies to enhance chemotherapeutic effect and improve the clinical outcome of MRT patients. This study evaluated the cellular response to cisplatin, a representative chemotherapeutic agent used in the treatment of MRT, and the role of autophagy in mediating cisplatin resistance. Our results demonstrated that cisplatin induced apoptosis and autophagy concomitantly in a panel of MRT cell lines. Furthermore, inhibition of caspase-induced apoptosis with Z-VAD-FMK also inhibited autophagy levels demonstrating a complex interplay between these two pathways. In addition, blocking autophagy at the early stages of the autophagic process using the pharmacological inhibitor SAR405 or through the genetic knockdown of critical autophagic protein ATG5 by siRNA did not sensitise cells to cisplatin-induced apoptosis. Collectively, these results suggest that induction of autophagy does not appear to elicit a pro-survival effect in the chemotherapeutic response of MRT cells.

miR-214 Modulates the Growth and Migration of Oral Cancer before and after Chemotherapy through Mediating ULK1

The role of miRNAs as crucial components in carcinogenesis has been well documented. However, whether and how miR-214 influences oral cancer cells' drug resistance remains to be elucidated, and its downstream targets are still under investigation. Hence, this research is aimed at determining miR-214 and ULK1 expression in oral cancer before and after chemotherapy and their correlations with cancer cell growth. Human oral normal epithelial cells and human tongue squamous cell carcinoma CAL-27 cells were cultured to detect miR-214 and ULK1 levels. It was found that before chemotherapy, miR-214 was higher, while ULK1 was underexpressed in CAL-27 cells, versus normal epithelial cells. After chemotherapy, miR-214 decreased obviously in CAL-27 cells, while ULK1 level increased significantly. In addition, autophagy-related genes (Beclin 1, mTOR, and P53) in CAL-27 cells were found to be significantly inhibited before chemotherapy and were obviously increased after chemotherapy. Moreover, to further determine the impacts of miR-214 and ULK1 on oral cancer cell growth after chemotherapy, the two were overexpressed or silenced in CAL-27 cells after transfection. We found that ULK1 could effectively decrease the activity and invasion of CAL-27 cells and increase their apoptosis level, while miR-214 could antagonize its antitumor effect. Therefore, miR-214 can be used as an early prognostic biomarker for oral cancer, and ULK1 is a new candidate therapeutic target.

Exploration of Different Hypoxia Patterns and Construction of a Hypoxia-Related Gene Prognostic Index in Colorectal Cancer

Introduction

Immune checkpoint inhibitor (ICI) therapy has been proven to be a highly efficacious treatment for colorectal adenocarcinoma (COAD). However, it is still unclear how to identify those who might benefit the most from ICI therapy. Hypoxia facilitates the progression of the tumor from different aspects, including proliferation, metabolism, angiogenesis, and migration, and improves resistance to ICI. Therefore, it is essential to conduct a comprehensive understanding of the influences of hypoxia in COAD and identify a biomarker for predicting the benefit of ICI.

Methods

An unsupervised consensus clustering algorithm was used to identify distinct hypoxia-related patterns for COAD patients from TCGA and the GEO cohorts. The ssGSEA algorithm was then used to explore the different biological processes, KEGG pathways, and immune characteristics among distinct hypoxia-related clusters. Some hypoxia-related hub genes were then selected by weighted gene coexpression network analysis (WGCNA). Subsequently, univariate Cox regression analysis, multivariate Cox regression analysis, and least absolute shrinkage and selection operator (LASSO) regression were utilized to construct a hypoxia-related gene prognostic index (HRGPI). Finally, validation was also conducted for HRGPI in prognostic value, distinguishing hypoxia-related characteristics and benefits of ICI.

Results

We identified four hypoxia-related clusters and found that different hypoxia response patterns induced different prognoses significantly. Again, we found different hypoxia response patterns presented distinct characteristics of biological processes, signaling pathways, and immune features. Severe hypoxia conditions promoted activation of some cancer-related signaling pathways, including Wnt, Notch, ECM-related pathways, and remodeled the tumor microenvironment of COAD, tending to present as an immune-excluded phenotype. Subsequently, we selected nine genes (ANO1, HOXC6, SLC2A4, VIP, CD1A, STC2, OLFM2, ATP6V1B1, HMCN2) to construct our HRGPI, which has shown an excellent prognostic value. Finally, we found that HRGPI has an advantage in distinguishing immune and molecular characteristics of hypoxia response patterns, and it could also be an excellent predictive indicator for clinical response to ICI therapy.

Conclusion

Different hypoxia response patterns activate different signaling pathways, presenting distinct biological processes and immune features. HRGPI is an independent prognostic factor for COAD patients, and it could also be used as an excellent predictive indicator for clinical response to ICI therapy.

The Potential of Epigallocatechin Gallate (EGCG) in Targeting Autophagy for Cancer Treatment: A Narrative Review

Autophagy is an evolutionarily conserved process for the degradation of redundant or damaged cellular material by means of a lysosome-dependent mechanism, contributing to cell homeostasis and survival. Autophagy plays a multifaceted and context-dependent role in cancer initiation, maintenance, and progression; it has a tumor suppressive role in the absence of disease and is upregulated in cancer cells to meet their elevated metabolic demands. Autophagy represents a promising but challenging target in cancer treatment. Green tea is a widely used beverage with healthy effects on several diseases, including cancer. The bioactive compounds of green tea are mainly catechins, and epigallocatechin-gallate (EGCG) is the most abundant and biologically active among them. In this review, evidence of autophagy modulation and anti-cancer effects induced by EGCG treatment in experimental cancer models is presented. Reviewed articles reveal that EGCG promotes cytotoxic autophagy often through the inactivation of PI3K/Akt/mTOR pathway, resulting in apoptosis induction. EGCG pro-oxidant activity has been postulated to be responsible for its anti-cancer effects. In combination therapy with a chemotherapy drug, EGCG inhibits cell growth and the drug-induced pro-survival autophagy. The selected studies rightly claim EGCG as a valuable agent in cancer chemoprevention.

Wnt5a-mediated autophagy promotes radiation resistance of nasopharyngeal carcinoma

Wnt signaling pathways and autophagy play an essential role in tumor progression. Canonical Wnt signaling pathways in radiation resistance have been studied in the past, but it remains unclear whether the noncanonical Wnt signaling pathways can affect tumor radiation resistance through protective autophagy. Nasopharyngeal carcinoma, a particular subtype of head and neck squamous cell carcinoma, relies on radiation therapy. In this study, we found that radioactive rays could significantly promote the expression of Wnt noncanonical signaling pathways ligands in nasopharyngeal carcinoma, among which Wnt5A was the most markedly altered. We have demonstrated that Wnt5a can reduce the radiation sensitivity of nasopharyngeal carcinoma in vitro and in vitro experiments. Meanwhile, we found much more greater autophagosomes in overexpressed-Wnt5A nasopharyngeal carcinoma cells by electron microscopy. Further mechanism exploration revealed that Beclin1 is the main target of Wnt5A, and knocking down Beclin1 can partially reduce Wnt5a-induced radiation resistance. By studying Wnt5A-mediated protective autophagy in promoting radiation resistance in nasopharyngeal carcinoma cells, we hope that the Wnt5A and Beclin1 can become effective targets for overcoming radiation resistance in the future.

ROS generation attenuates the anti-cancer effect of CPX on cervical cancer cells by inducing autophagy and inhibiting glycophagy

Cervical cancer is one of the most common gynecological malignancies with poor prognosis due to constant chemoresistance and repeated relapse. Ciclopirox olamine (CPX), a synthetic antifungal agent, has recently been identified to be a promising anti-cancer candidate. However, the detailed mechanisms related to its anti-cancer effects remain unclear and need to be further elucidated. In this study, we found that CPX could induce proliferation inhibition in cervical cancer cells by targeting PARK7. Further results demonstrated that CPX could induce cytoprotective autophagy by downregulating the expression of PARK7 to activate PRKAA1 or by PARK7-independent accumulation of ROS to inhibit mTOR signaling. Meanwhile, CPX treatment increased the glycogen clustering and glycophagy in cervical cancer cells. The presence of N-acetyl-l-cysteine (NAC), a ROS scavenger, led to further clustering of glycogen in cells by reducing autophagy and enhancing glycophagy, which promoted CPX-induced inhibition of cervical cancer cell proliferation. Together, our study provides new insights into the molecular mechanisms of CPX in the anti-cancer therapy and opens new avenues for the glycophagy in cancer therapeutics.

•

CPX induces cytoprotective autophagy and inhibits proliferation of cervical cancer cells by targeting PARK7.

•

ROS generation attenuates the anticancer effect of CPX by inducing cytoprotective autophagy and inhibiting glycophagy.

•

ROS-triggered glycogen clustering and inactivation of YAP1 are involved in the anti-cancer effects of CPX.