New Insights into the Role of Autophagy in Tumor Immune Microenvironment

TRIM47 promotes head and neck squamous cell carcinoma malignant progression by degrading XAF1 through ubiquitination

Tripartite motif-containing 47 (TRIM47) is a member of the TRIM family, which has E3 ligase activity and has been demonstrated to be involved in tumor development. In this work, we found that TRIM47 is highly expressed in head and neck squamous cell carcinomas (HNSCC) tissues. TRIM47 overexpression promoted HNSCC cell proliferation. Downregulation of TRIM47 suppressed HNSCC cell proliferation and promoted apoptosis and autophagy. TRIM47 suppression caused cell proliferation inhibition and apoptosis promotion could be reversed by 3-MA, an autophagy inhibitor. In mechanism, TRIM47 interacted with XIAP-associated factor 1 (XAF1), promoting its ubiquitination and degradation. XAF1 promoted HNSCC cell apoptosis and autophagy. TRIM47 overexpression caused cell proliferation promotion and autophagy inhibition could be reversed by XAF1 overexpression. Animal experiments confirmed that the knockdown of TRIM47 inhibits tumor growth in vivo. Ultimately, TRIM47 promotes the ubiquitination and degradation of XAF1 and suppresses apoptosis and autophagy to promote the progression of HNSCC.

Dissecting the multifaceted roles of autophagy in cancer initiation, growth, and metastasis: from molecular mechanisms to therapeutic applications

Autophagy is a cytoplasmic defense mechanism that cells use to break and reprocess their intracellular components. This utilization of autophagy is regarded as a savior in nutrient-deficient and other stressful conditions. Hence, autophagy keeps contact with and responds to miscellaneous cellular tensions and diverse pathways of signal transductions, such as growth signaling and cellular death. Importantly, autophagy is regarded as an effective tumor suppressor because regular autophagic breakdown is essential for cellular maintenance and minimizing cellular damage. However, paradoxically, autophagy has also been observed to promote the events of malignancies. This review discussed the dual role of autophagy in cancer, emphasizing its influence on tumor survival and progression. Possessing such a dual contribution to the malignant establishment, the prevention of autophagy can potentially advocate for the advancement of malignant transformation. In contrast, for the context of the instituted tumor, the agents of preventing autophagy potently inhibit the advancement of the tumor. Key regulators, including calpain 1, mTORC1, and AMPK, modulate autophagy in response to nutritional conditions and stress. Oncogenic mutations like RAS and B-RAF underscore autophagy's pivotal role in cancer development. The review also delves into autophagy's context-dependent roles in tumorigenesis, metastasis, and the tumor microenvironment (TME). It also discusses the therapeutic effectiveness of autophagy for several cancers. The recent implication of autophagy in the control of both innate and antibody-mediated immune systems made it a center of attention to evaluating its role concerning tumor antigens and treatments of cancer.

Selective autophagy in cancer: mechanisms, therapeutic implications, and future perspectives

Eukaryotic cells engage in autophagy, an internal process of self-degradation through lysosomes. Autophagy can be classified as selective or non-selective depending on the way it chooses to degrade substrates. During the process of selective autophagy, damaged and/or redundant organelles like mitochondria, peroxisomes, ribosomes, endoplasmic reticulum (ER), lysosomes, nuclei, proteasomes, and lipid droplets are selectively recycled. Specific cargo is delivered to autophagosomes by specific receptors, isolated and engulfed. Selective autophagy dysfunction is closely linked with cancers, neurodegenerative diseases, metabolic disorders, heart failure, etc. Through reviewing latest research, this review summarized molecular markers and important signaling pathways for selective autophagy, and its significant role in cancers. Moreover, we conducted a comprehensive analysis of small-molecule compounds targeting selective autophagy for their potential application in anti-tumor therapy, elucidating the underlying mechanisms involved. This review aims to supply important scientific references and development directions for the biological mechanisms and drug discovery of anti-tumor targeting selective autophagy in the future.

Pollen self-elimination CRISPR-Cas genome editing prevents transgenic pollen dispersal in maize

This study reports the development of a programmed pollen self-elimination CRISPR-Cas (PSEC) system in which the pollen is infertile when PSEC is present in haploid pollen. PSEC can be inherited through the female gametophyte and retains genome editing activity in vivo across generations. This system could greatly alleviate serious concerns about the widespread diffusion of genetically modified (GM) elements into natural and agricultural environments via outcrossing.

Epinodosin suppresses the proliferation, invasion, and migration of esophageal squamous cell carcinoma by mediating miRNA-143-3p/Bcl-2 axis

Epinodosin has shown antibacterial and antitumor biological characteristics in the documents. We found that Epinodosin has an effective inhibitory effect on esophageal squamous cell carcinoma (ESCC). However, the potential roles and mechanisms of Epinodosin in ESCC remain unclear. We performed many experiments to clarify the effect and mechanism of Epinodosin on ESCC. In this study, cell viability, invasion, migration, and apoptosis were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,-diphenytetrazoliumromide (MTT), Transwell, and flow cytometry. The differentially expressed miRNAs were screened through RNA transcriptome sequencing. The expression levels of miRNA-143-3p and some proteins were measured by real-time polymerase chain reaction (PCR) and Western blot. The anticancer effects of Epinodosin in vivo were determined by a nude mouse model. Epinodosin suppressed cell proliferation/invasion/migration and induced ESCC cell apoptosis. Epinodosin remarkably affected the protein expression of mitogen-activated protein kinase (MAPK) signaling pathway. The animal experiments demonstrated that Epinodosin could attenuate the growth of ESCC tumors in nude mice. The expression of p53, Bim, and Bax was upregulated, while that of Bcl-2 was downregulated in tumor tissues. In conclusion, Epinodosin suppresses cell viability/invasion/migration, while induces ESCC cell apoptosis by mediating miRNA-143-3p and Bcl-2, and can markedly attenuate the growth of ESCC tumors in nude mice.

Autoimmunity and Carcinogenesis: Their Relationship under the Umbrella of Autophagy

The immune system and autophagy share a functional relationship. Both innate and adaptive immune responses involve autophagy and, depending on the disease's origin and pathophysiology, it may have a detrimental or positive role on autoimmune disorders. As a "double-edged sword" in tumors, autophagy can either facilitate or impede tumor growth. The autophagy regulatory network that influences tumor progression and treatment resistance is dependent on cell and tissue types and tumor stages. The connection between autoimmunity and carcinogenesis has not been sufficiently explored in past studies. As a crucial mechanism between the two phenomena, autophagy may play a substantial role, though the specifics remain unclear. Several autophagy modifiers have demonstrated beneficial effects in models of autoimmune disease, emphasizing their therapeutic potential as treatments for autoimmune disorders. The function of autophagy in the tumor microenvironment and immune cells is the subject of intensive study. The objective of this review is to investigate the role of autophagy in the simultaneous genesis of autoimmunity and malignancy, shedding light on both sides of the issue. We believe our work will assist in the organization of current understanding in the field and promote additional research on this urgent and crucial topic.

Novel 2-Amino-1,4-Naphthoquinone Derivatives Induce A549 Cell Death through Autophagy

A series of 1,4-naphthoquinone derivatives containing were synthesized as anti-cancer agents and the crystal structure of compound 5a was confirmed by X-ray diffraction. In addition, the inhibitory activities against four cancer cell lines (HepG2, A549, K562, and PC-3) were tested, respectively, and compound 5i showed significant cytotoxicity on the A549 cell line with the IC₅₀ of 6.15 μM. Surprisingly, in the following preliminary biological experiments, we found that compound 5i induced autophagy by promoting the recycling of EGFR and signal transduction in the A549 cell, resulting in the activation of the EGFR signal pathway. The potential binding pattern between compound 5i and EGFR tyrosine kinase (PDB ID: 1M17) was also identified by molecular docking. Our research paves the way for further studies and the development of novel and powerful anti-cancer drugs.

Targeting Autophagy Using Long Non-Coding RNAs (LncRNAs): New Landscapes in the Arena of Cancer Therapeutics

Cancer has become a global health hazard accounting for 10 million deaths in the year 2020. Although different treatment approaches have increased patient overall survival, treatment for advanced stages still suffers from poor clinical outcomes. The ever-increasing prevalence of cancer has led to a reanalysis of cellular and molecular events in the hope to identify and develop a cure for this multigenic disease. Autophagy, an evolutionary conserved catabolic process, eliminates protein aggregates and damaged organelles to maintain cellular homeostasis. Accumulating evidence has implicated the deregulation of autophagic pathways to be associated with various hallmarks of cancer. Autophagy exhibits both tumor-promoting and suppressive effects based on the tumor stage and grades. Majorly, it maintains the cancer microenvironment homeostasis by promoting viability and nutrient recycling under hypoxic and nutrient-deprived conditions. Recent investigations have discovered long non-coding RNAs (lncRNAs) as master regulators of autophagic gene expression. lncRNAs, by sequestering autophagy-related microRNAs, have been known to modulate various hallmarks of cancer, such as survival, proliferation, EMT, migration, invasion, angiogenesis, and metastasis. This review delineates the mechanistic role of various lncRNAs involved in modulating autophagy and their related proteins in different cancers.

Metabolic Pathways as a Novel Landscape in Pancreatic Ductal Adenocarcinoma

Metabolism plays a fundamental role in both human physiology and pathology, including pancreatic ductal adenocarcinoma (PDAC) and other tumors. Anabolic and catabolic processes do not only have energetic implications but are tightly associated with other cellular activities, such as DNA duplication, redox reactions, and cell homeostasis. PDAC displays a marked metabolic phenotype and the observed reduction in tumor growth induced by calorie restriction with in vivo models supports the crucial role of metabolism in this cancer type. The aggressiveness of PDAC might, therefore, be reduced by interventions on bioenergetic circuits. In this review, we describe the main metabolic mechanisms involved in PDAC growth and the biological features that may favor its onset and progression within an immunometabolic context. We also discuss the need to bridge the gap between basic research and clinical practice in order to offer alternative therapeutic approaches for PDAC patients in the more immediate future.

Expression and Content of Protein LC3B in Gastric Cancer Tissue, Relationship with Expression of mTOR, AMPK in Gastric Cancer Tissue and HER2 and PD-L1 Status of the Tumor

Analysis of HER2 status of the tumor and expression of mTOR, AMPK showed a decrease in mTOR mRNA level in HER2⁺ tumors in comparison with HER- status. The appearance of PD-L1⁺ transformed cells in the tumor was associated with increased expression of the LC3B gene and elevated content of the corresponding protein measured after treatment.

Identification of Autophagy Related circRNA-miRNA-mRNA-Subtypes Network With Radiotherapy Responses and Tumor Immune Microenvironment in Non-small Cell Lung Cancer

Lung cancer (LC) is one of the most frequently diagnosed cancers and the leading cause of cancer death worldwide, and most LCs are non-small cell lung cancer (NSCLC). Radiotherapy is one of the most effective treatments for patients with lung cancer, either alone or in combination with other treatment methods. However, radiotherapy responses vary considerably among NSCLC patients. The efficacy of radiotherapy is influenced by several factors, among which autophagy is of importance. Autophagy is induced by radiotherapy and also influences cell responses to radiation. We explored the clinical significance of autophagy-related genes (ARGs) and gene sets (ARGSs) and the underlying mechanism in NSCLC patients treated with radiotherapy. First, differentially expressed ARGs (SNCA, SESN3, DAPL1, and ELAPOR1) and miRNAs (miR-205-5p, miR-26a-1-3p, miR-6510-3p, miR-194-3p, miR-215-5p, and miR-375-3p) were identified between radiotherapy-resistant and radiotherapy-sensitive groups. An autophagy-related radiosensitivity risk signature (ARRS) by nine ARmRNAs/miRNAs and an autophagy-related overall survival risk signature (AROS) by three ARmRNAs were then constructed with estimated AUCs of 0.8854 (95% CI: 0.8131–0.9576) and 0.7901 (95% CI: 0.7168–0.8685), respectively. The correlations between ARGSs or prognostic signatures and clinicopathological factors, short-term radiotherapy responses (radiotherapy sensitivity), long-term radiotherapy responses (overall survival), and immune characteristics were analyzed. Both ARGSs and prognostic signatures were related to immune checkpoint inhibitors (ICIs), infiltration of tumor-infiltrating immune cells (TIICs), and the activity of the cancer immune cycle. Finally, after target prediction and correlation analysis, circRNA (hsa_circ_0019709, hsa_circ_0081983, hsa_circ_0112354, hsa_circ_0040569, hsa_circ_0135500, and hsa_circ_0098966)-regulated miRNA/ARmRNA axes (miR-194-3p/SESN3, miR-205-5p/ELAPOR1, and miR-26a-1-3p/SNCA) were considered potential modulatory mechanisms by influencing the regulation of autophagy, macroautophagy, and chaperone-mediated autophagy.

Advances in autophagy as a target in the treatment of tumours

Autophagy is a multi-step lysosomal degradation process, which regulates energy and material metabolism and has been used to maintain homeostasis. Autophagy has been shown to be involved in the regulation of health and disease. But at present, there is no consensus on the relationship between autophagy and tumour, and we consider that it plays a dual role in the occurrence and development of tumour. That is to say, under certain conditions, it can inhibit the occurrence of tumour, but it can also promote the process of tumour. Therefore, autophagy could be used as a target for tumour treatment. The regulation of autophagy plays a synergistic role in the radiotherapy, chemotherapy, phototherapy and immunotherapy of tumour, and nano drug delivery system provides a promising strategy for improving the efficacy of autophagy regulation. This review summarised the progress in the regulatory pathways and factors of autophagy as well as nanoformulations as carriers for the delivery of autophagy modulators.

Molecular pathways in viral hepatitis-associated liver carcinogenesis: An update

Hepatocellular carcinoma (HCC) is the most common type of cancer among primary malignant tumors of the liver and is a consequential cause of cancer-related deaths worldwide. In recent years, uncovering the molecular mechanisms involved in the development and behavior of this tumor has led to the identification of multiple potential treatment targets. Despite the vast amount of data on this topic, HCC remains a challenging tumor to treat due to its aggressive behavior and complex molecular profile. Therefore, the number of studies aiming to elucidate the mechanisms involved in both carcinogenesis and tumor progression in HCC continues to increase. In this context, the close association of HCC with viral hepatitis has led to numerous studies focusing on the direct or indirect involvement of viruses in the mechanisms contributing to tumor development and behavior. In line with these efforts, this review was undertaken to highlight the current understanding of the molecular mechanisms by which hepatitis B virus (HBV) and hepatitis C virus (HCV) participate in oncogenesis and tumor progression in HCC and summarize new findings. Cumulative evidence indicates that HBV DNA integration promotes genomic instability, resulting in the overexpression of genes related to cancer development, metastasis, and angiogenesis or inactivation of tumor suppressor genes. In addition, genetic variations in HBV itself, especially preS2 deletions, may play a role in malignant transformation. Epigenetic dysregulation caused by both viruses might also contribute to tumor formation and metastasis by modifying the methylation of DNA and histones or altering the expression of microRNAs. Similarly, viral proteins of both HBV and HCV can affect pathways that are important anticancer targets. The effects of these two viruses on the Hippo-Yap-Taz pathway in HCC development and behavior need to be investigated. Additional, comprehensive studies are also needed to determine these viruses' interaction with integrins, farnesoid X, and the apelin system in malignant transformation and tumor progression. Although the relationship of persistent inflammation caused by HBV and HCV hepatitis with carcinogenesis is well defined, further studies are warranted to decipher the relationship among inflammasomes and viruses in carcinogenesis and elucidate the role of virus-microbiota interactions in HCC development and progression.

S-Allylmercapto-N-acetylcysteine ameliorates elastase-induced chronic obstructive pulmonary disease in mice via regulating autophagy

Autophagy-impairment is involved in the pathological process of chronic obstructive pulmonary disease (COPD), and relates to inflammation and emphysema in lung injury. This study aimed to elucidate the protective effect of S-Allylmercapto-N-acetylcysteine (ASSNAC) against COPD via regulating the autophagy. Firstly, porcine pancreatic elastase (PPE)-induced COPD model in A549 cells was established, and ASSNAC was verified to alleviate the autophagy-impairment from the results of western blotting analysis of LC3BⅡ/Ⅰ and monodansylcadaverine (MDC) staining of autophagosome. Secondly, Balb/c mice were stimulated by PPE to induce the COPD model in vivo. The histological analysis of lung tissues presented that ASSNAC could alleviate the lung injury induced by PPE. Thirdly, the secretions of NO, TNF-α and IL-1β in serum and BALF were reduced by ASSNAC compared with the PPE group. Finally, the mechanism of therapeutic effects of ASSNAC against COPD through regulating the autophagy-impairment was clarified. That is, ASSNAC inhibits the phosphorylation of PI3K/Akt/mTOR signaling pathways. In a word, this research provides a reference for ASSNAC to be an effective drug for pulmonary diseases.

Berberine-induced TFEB deacetylation by SIRT1 promotes autophagy in peritoneal macrophages

Atherosclerosis is a chronic inflammatory disease that commonly affects the elderly and is characterized by vascular damage, macrophage infiltration, and plaque formation. Moreover, it increases the risk of cardiovascular disease. The pathogenesis of atherosclerosis involves an interplay between macrophage autophagy and apoptosis. A recently discovered transcription factor, transcription factor EB (TFEB) is known to activate autophagy in macrophages. Sirtuin deacetylase 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylase, activates several transcription factors, including TFEB. We studied the effects of berberine on the NAD⁺ synthesis pathway and interactions between SIRT1 and TFEB. We also studied the effects of berberine-induced TFEB activation via SIRT1 on autophagy and apoptosis of peritoneal macrophages. We found that berberine promoted autophagy of peritoneal macrophages by activating SIRT1 via the NAD⁺ synthesis pathway and, in turn, promoting TFEB nuclear translocation and deacetylation. The functional regulation of SIRT1 and TFEB by berberine could be exploited as a potential therapeutic strategy for atherosclerosis.

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.

Antiproliferative effects of L-asparaginase in acute myeloid leukemia

The antitumor enzyme L-asparaginase (L-Asp) has commonly been used for the treatment of acute lymphoblastic leukemia. However, the effects of L-Asp on acute myeloid leukemia (AML) and their underlying mechanisms have not been fully elucidated. In the present study, the effects of L-Asp on cell proliferation and apoptosis were investigated using the AML cell lines U937, HL-60 and KG-1a. The effects of combining L-Asp with mitoxantrone (MIT) and cytarabine (Ara-c) were also analyzed. The combination of MIT and Ara-C is known as MA therapy, and is a widely used therapeutic regimen for the treatment of elderly patients with refractory AML. When applied alone, L-Asp inhibited cell proliferation and induced apoptosis in each of the cell lines tested. Furthermore, the combined use of L-Asp with MA therapy further potentiated the inhibition of cell proliferation while increasing the induction of apoptosis. These findings provide evidence for the potential antitumor effect of L-Asp in AML, and indicate that improved efficacy maybe achieved by combining L-Asp with MIT and Ara-c. This combination may provide a promising new therapeutic strategy for the treatment of AML.

The Multifaceted Effects of Autophagy on the Tumor Microenvironment

The tumor microenvironment is composed of cancer cells, noncancer cells (e.g., immune cells, stromal cells, endothelial cells, and adipocytes), and various mediators (e.g., cytokines, chemokines, growth factors, and humoral factors) that work together to support cancer growth, progression, and resistance to therapies. Autophagy is an evolutionarily conserved degradation mechanism by which various cytosolic cargos (e.g., damaged organelles, unused molecules, or invaded pathogens) are engulfed by double-membrane autophagosomes, and then delivered into the lysosome for degradation and recycling. The level of autophagy is a crucial threshold to either promote cell survival or induce cell death in response to environmental stresses. Autophagy plays a context-dependent role in tumorigenesis and anticancer therapy via shaping the inflammatory, hypoxic, immunosuppressive, and metabolic tumor microenvironment. In particular, impaired autophagy flux is associated with chronic inflammation, immunosuppression, stromal formation, cancer stemness, angiogenesis, metastasis, and metabolic reprogramming in the tumor microenvironment. Understanding the molecular machinery of autophagy and its communication with hallmarks of cancer could lead to potential new anticancer strategies or drugs.

Oleic Acid Protects against Hepatic Ischemia and Reperfusion Injury in Mice by Inhibiting AKT/mTOR Pathways

Hepatic ischemia-reperfusion (I/R) injury is a serious complication in patients who have undergone hepatic surgery such as orthotopic liver transplantation and partial hepatectomy. Recently, a new cytoprotective agent, ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), was reported to protect against hepatic I/R injury. However, the protective mechanism of UDCA-LPE is not fully understood. Therefore, we conducted this study to explore its underlying mechanism. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze the liver lipid metabolism changes in mice during I/R. KEGG enrichment indicated that UDCA-LPE is likely to exert its protective role by regulating fatty acid (FA) metabolism. Further analysis found that UDCA-LPE significantly increased the ratio of oleic acid (OA) to palmitic acid (PA). We found that mice pretreated with OA improved tolerance to hepatic I/R injury. In addition, the phosphorylation level of AKT was markedly upregulated during oxidative stress to promote p65 nuclear translocation, triggering an inflammatory response that exacerbated cell damage and OA treatment significantly inhibited this process. Notably, OA was found to inhibit H2O2-induced oxidative stress, inflammation, and cell death in HepG2 cells. Furthermore, we found that OA supplementation to the medium did not result in a significant increase in intracellular OA, but marked increase in the ratio of OA to PA, which may be an important mechanism for the inflammatory response induced by oxidative stress during I/R. Finally, we demonstrated that OA increased the level of autophagy in HepG2 cells, which may be one of the protective mechanisms against oxidative stress. Collectively, this study revealed that FA metabolism functionally determines the oxidative stress-related inflammation caused by hepatic I/R. We hypothesize that OA treatment may be a promising strategy for preventing and treating I/R-induced liver damage.

A Novel Probe for Spliceosomal Proteins that Induces Autophagy and Death of Melanoma Cells Reveals New Targets for Melanoma Drug Discovery

Background/Aims:

Despite recent advances in melanoma drug discovery, the average overall survival of patients with late stage metastatic melanoma is approximately 3 years, suggesting a need for approaches that identify new melanoma targets. We have previously reported a discovery of novel anti-melanoma compound 2155–14 (Onwuha-Ekpete et al., J Med Chem. 2014 Feb 27; 57(4):1599–608). In the report presented herein we aim to identify its target(s) and mechanism of action.

Methods:

We utilized biotinylated analog of 2155–14 to pull down its targets from melanoma cells. Proteomics in combination with western blot were used to identify the targets. Mechanism of action of 2155–14 was determined using flow cytometry, RT-PCR, microscopy, western blot, and enzymatic activity assays. Where applicable, one-way analysis of variance (ANOVA) was used followed by Dunnett post hoc test.

Results:

In the present study, we identified ATP-dependent RNA helicase DDX1 and heterogeneous nuclear ribonucleoproteins (hnRNPs) H1, H2 and A2/B1 as targets of anti-melanoma compound 2155–14. To the best of our knowledge, this is a first report suggesting that these proteins could be targeted for melanoma therapy. Mechanistic investigations showed that 2155–14 induces ER stress leading to potentiation of basal autophagy resulting in melanoma cell death in BRAF and NRAS mutated melanoma cells.

Conclusion:

Identification of mode of action of 2155–14 may provide insight into novel therapies against a broad range of melanoma subtypes. These studies were enabled by the novel probe derived from a mixture-based library, an important class of chemical biology tools for discovering novel targets.

Role of hypoxia in cancer therapy by regulating the tumor microenvironment

AIM

Clinical resistance is a complex phenomenon in major human cancers involving multifactorial mechanisms, and hypoxia is one of the key components that affect the cellular expression program and lead to therapy resistance. The present study aimed to summarize the role of hypoxia in cancer therapy by regulating the tumor microenvironment (TME) and to highlight the potential of hypoxia-targeted therapy.

METHODS

Relevant published studies were retrieved from PubMed, Web of Science, and Embase using keywords such as hypoxia, cancer therapy, resistance, TME, cancer, apoptosis, DNA damage, autophagy, p53, and other similar terms.

RESULTS

Recent studies have shown that hypoxia is associated with poor prognosis in patients by regulating the TME. It confers resistance to conventional therapies through a number of signaling pathways in apoptosis, autophagy, DNA damage, mitochondrial activity, p53, and drug efflux.

CONCLUSION

Hypoxia targeting might be relevant to overcome hypoxia-associated resistance in cancer treatment.

The Molecular Mechanism of Epithelial-Mesenchymal Transition for Breast Carcinogenesis

The transforming growth factor-β (TGF-β) signaling pathway plays multiple regulatory roles in the tumorigenesis and development of cancer. TGF-β can inhibit the growth and proliferation of epithelial cells and induce apoptosis, thereby playing a role in inhibiting breast cancer. Therefore, the loss of response in epithelial cells that leads to the inhibition of cell proliferation due to TGF-β is a landmark event in tumorigenesis. As tumors progress, TGF-β can promote tumor cell invasion, metastasis, and drug resistance. At present, the above-mentioned role of TGF-β is related to the interaction of multiple signaling pathways in the cell, which can attenuate or abolish the inhibition of proliferation and apoptosis-promoting effects of TGF-β and enhance its promotion of tumor progression. This article focuses on the molecular mechanisms through which TGF-β interacts with multiple intracellular signaling pathways in tumor progression and the effects of these interactions on tumorigenesis.

Discovery of a new autophagy inducer for A549 lung cancer cells

Biological activities of a series of fluorescent compounds against human lung cancer cell line A549 were investigated. The results showed that (E)-1,3,3-trimethyl-2-(4-(piperidin-1-yl)styryl)-3H-indol-1-ium iodide (8) and (E)-2-(5,5-dimethyl-3-(4-(piperazin-1-yl)styryl)cyclohex-2-en-1-ylidene) malononitrile (11) could inhibit the growth of A549 cancer cells in a dose and time-dependent manner. Furthermore, compound 8 could trigger autophagy and apoptosis, but not obviously induce necrosis under the stimulatory condition. Therefore, 8 can be used as autophagy activator to investigate the regulatory mechanism of autophagy and may offer a new candidate for the treatment of lung cancer.

MicroRNA in Ovarian Cancer: Biology, Pathogenesis, and Therapeutic Opportunities

Ovarian cancer comprises one of the three major malignant tumor types in the female reproductive system. The mortality rate of this cancer is the highest among all gynecological tumors, with ovarian cancer metastasis constituting an important cause of death. Therefore, markers for disease prediction and prognosis are highly desirable for early diagnosis as well as for helping optimize and personalize treatment. Recently, microRNAs (miRNAs), which consist of short-sequence RNAs that do not encode a protein, have emerged as new biomarkers in the clinical diagnosis and treatment of ovarian cancer. By pairing with bases specific to the target messenger RNA (mRNA), miRNAs cause degradation of the target mRNA or inhibit its translation, thereby regulating various cellular processes including cell proliferation and adhesion. Increasing numbers of studies have shown that miRNA expression abnormality plays an important role in the development of ovarian cancer. In this review, we discuss the mechanisms of miRNA action, current research regarding their role in the suppression or promotion of ovarian cancer, and their use as markers for diagnosis of prognosis or as therapeutic targets for this disease. Finally, we present future perspectives regarding the clinical management of ovarian cancer and the role for miRNAs therein.

The relationship between autophagy and the immune system and its applications for tumor immunotherapy

Autophagy is a genetically well-controlled cellular process that is tightly controlled by a set of core genes, including the family of autophagy-related genes (ATG). Autophagy is a “double-edged sword” in tumors. It can promote or suppress tumor development, which depends on the cell and tissue types and the stages of tumor. At present, tumor immunotherapy is a promising treatment strategy against tumors. Recent studies have shown that autophagy significantly controls immune responses by modulating the functions of immune cells and the production of cytokines. Conversely, some cytokines and immune cells have a great effect on the function of autophagy. Therapies aiming at autophagy to enhance the immune responses and anti-tumor effects of immunotherapy have become the prospective strategy, with enhanced antigen presentation and higher sensitivity to CTLs. However, the induction of autophagy may also benefit tumor cells escape from immune surveillance and result in intrinsic resistance against anti-tumor immunotherapy. Increasing studies have proven the optimal use of either ATG inducers or inhibitors can restrain tumor growth and progression by enhancing anti-tumor immune responses and overcoming the anti-tumor immune resistance in combination with several immunotherapeutic strategies, indicating that induction or inhibition of autophagy might show us a prospective therapeutic strategy when combined with immunotherapy. In this article, the possible mechanisms of autophagy regulating immune system, and the potential applications of autophagy in tumor immunotherapy will be discussed.

Ginsenoside metabolite compound K induces apoptosis and autophagy in non-small cell lung cancer cells via AMPK-mTOR and JNK pathways

Compound K [C-K; 20-O-(β-d-glucopyranosyl)-20(S)-protopanaxadiol], as a metabolite of ginsenoside, has been verified to have antitumor effects in various cancers, including non-small cell lung cancer (NSCLC). However, the detailed mechanisms of C-K in NSCLC remain largely unknown. In this study, we aimed to evaluate the effect of C-K on apoptosis and autophagy in NSCLC cells as well as its related mechanisms. According to the results, C-K suppressed the proliferation, and led to G1 phase arrest and apoptosis in A549 and H1975 cells. Subsequently, C-K promoted autophagy, as confirmed by the enhanced rate of cells staining positive with acridine orange, increased levels of LC3II and Beclin-1, and with decreased levels of p62 in A549 and H1975 cells. Moreover, 3-methyladenine (3-MA; an inhibitor of autophagy) effectively suppressed the inhibition of proliferation and apoptosis that was induced with C-K. Finally, C-K treatment promoted the activation of the AMPK-mTOR and c-Jun N-terminal kinase (JNK) signaling pathways. Treatment with compound C (AMPK inhibitor) or SP600125 (JNK inhibitor) significantly restrained the inhibition of proliferation, apoptosis, and autophagy induced with C-K in A549 and H1975 cells. In conclusion, this study demonstrates that C-K promotes autophagy-mediated apoptosis in NSCLC via AMPK-mTOR and JNK signaling pathways.

Molecular Targets in Hepatocarcinogenesis and Implications for Therapy

Hepatocarcinogenesis comprises of multiple, complex steps that occur after liver injury and usually involve several pathways, including telomere dysfunction, cell cycle, WNT/β-catenin signaling, oxidative stress and mitochondria dysfunction, autophagy, apoptosis, and AKT/mTOR signaling. Following liver injury, gene mutations, accumulation of oxidative stress, and local inflammation lead to cell proliferation, differentiation, apoptosis, and necrosis. The persistence of this vicious cycle in turn leads to further gene mutation and dysregulation of pro- and anti-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, IL-10, IL-12, IL-13, IL-18, and transforming growth factor (TGF)-β, resulting in immune escape by means of the NF-κB and inflammasome signaling pathways. In this review, we summarize studies focusing on the roles of hepatocarcinogenesis and the immune system in liver cancer. In addition, we furnish an overview of recent basic and clinical studies to provide a strong foundation to develop novel anti-carcinogenesis targets for further treatment interventions.

A Sterol from Soft Coral Induces Apoptosis and Autophagy in MCF-7 Breast Cancer Cells

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that plays a key role in regulating cellular metabolism, and is a therapeutic target for cancer therapy. To search for potential PPARγ activators, a compound library comprising 11 marine compounds was examined. Among them, a sterol, 3β,11-dihydroxy-9,11-secogorgost-5-en-9-one (compound 1), showed the highest PPARγ activity with an IC₅₀ value of 8.3 μM for inhibiting human breast adenocarcinoma cell (MCF-7) growth. Western blotting experiments showed that compound 1 induces caspase activation and PARP cleavage. In addition, compound 1 modulated the expression of various PPARγ-regulated downstream biomarkers including cyclin D1, cyclin-dependent kinase (CDK)6, B-cell lymphoma 2 (Bcl-2), p38, and extracellular-signal-regulated kinase (ERK). Moreover, compound 1 increased reactive oxygen species (ROS) generation, upregulated the phosphorylation and expression of H2AX, and induced autophagy. Interestingly, pre-treatment with the autophagy inhibitor 3-methyladenine rescued cells from compound 1-induced growth inhibition, which indicates that the cytotoxic effect of compound 1 is, in part, attributable to its ability to induce autophagy. In conclusion, these findings suggest the translational potential of compound 1 in breast cancer therapy.

Combining chloroquine with RAD001 inhibits tumor growth in a NEN mouse model

Patients with neuroendocrine neoplasms (NENs) often require systemic treatment, which is frequently limited by the emergence of drug resistance. mTOR inhibitors (mTORi), such as RAD001 (everolimus), have been shown to inhibit neoplasm progression. mTORi stimulates autophagy, a degradation pathway that might promote the survival of neoplasm cells that are exposed to anti-cancer therapy. Chloroquine (CQ), a well-known anti-malarial and anti-rheumatic drug, suppresses autophagy. Based on our previous results, we hypothesized that CQ may enhance the anti-tumorigenic effects of mTORi by inhibiting autophagy and we aimed to examine the anti-tumorigenic effect of CQ, alone or in combination with RAD001. We established a NEN subcutaneous xenograft mouse model and evaluated the effect of the drugs on tumor growth, mTOR pathway, autophagy and apoptosis. CQ alone and in combination with RAD001 significantly decreased neoplasm volume. Histopathological analysis revealed that the combination of CQ and RAD001 markedly inhibited mTOR activity and neoplasm cell growth, along with accumulation of autophagosomes and increased apoptosis. In conclusion, CQ enhances the anti-tumorigenic effect of RAD001 in vivo by inhibiting autophagy. Clinical trials addressing the effects of CQ therapy on neoplasm progression in patients with NENs, mainly in those treated with mTORi, are warranted.

The Long Noncoding RNA HOTAIR in Breast Cancer: Does Autophagy Play a Role?

HOTAIR (HOX transcript antisense RNA) plays a critical role in chromatin dynamics through the interaction with histone modifiers resulting in transcriptional gene silencing. The promoter of the HOTAIR gene contains multiple estrogen response elements (EREs) and is transcriptionally activated by estradiol in estrogen receptor-positive breast cancer cells. HOTAIR competes with BRCA1, a critical protein in breast cancer and is a critical regulator of genes involved in epithelial-to-mesenchymal transition. It mediates an oncogenic action of c-Myc, essential for breast carcinogenesis. The carcinogenic action of HOTAIR was confirmed in breast cancer stem-like cells, in which it was essential for self-renewal and proliferation. Several miRNAs regulate the expression of HOTAIR and HOTAIR interacts with many miRNAs to support cancer transformation. Many studies point at miR-34a as a major component of HOTAIR–miRNAs–cancer cross-talk. The most important role of HOTAIR can be attributed to cancer progression as its overexpression stimulates invasion and metastasis. HOTAIR can regulate autophagy, important for breast cancer cells survival, through the interaction with miRNAs specific for autophagy genes and directly with these genes. The role of HOTAIR-mediated autophagy in breast cancer progression can be underlined by its interaction with matrix metalloproteinases, essential for cancer invasion, and β-catenin can be important for this interaction. Therefore, there are several mechanisms of the interplay between HOTAIR and autophagy important for breast cancer, but further studies are needed to determine more details of this interplay.