Impact of context-dependent autophagy states on tumor progression

Targeting the TRIM14/USP14 Axis Enhances Immunotherapy Efficacy by Inducing Autophagic Degradation of PD-L1

Immunotherapy has greatly improved cancer treatment in recent years by harnessing the immune system to target cancer cells. The first immunotherapeutic agent approved by the FDA was IFNα. Treatment with IFNα can lead to effective immune activation and attenuate tumor immune evasion, but persistent treatment has been shown to elicit immunosuppressive effects. Here, we identified an autophagy-dependent mechanism by which IFNα triggers tumor immune evasion by upregulating PD-L1 to suppress the antitumor activity of CD8+ T cells. Mechanistically, IFNα increased the transcription of TRIM14, which recruited the deubiquitinase USP14 to inhibit the autophagic degradation of PD-L1. USP14 removed K63-linked ubiquitin chains from PD-L1, impairing its recognition by the cargo receptor p62 (also known as SQSTM1) for subsequent autophagic degradation. Combining the USP14 inhibitor IU1 with IFNα and anti-CTLA4 treatment effectively suppressed tumor growth without significant toxicity. This work suggests a strategy for targeting selective autophagy to abolish PD-L1-mediated cancer immune evasion. Significance: IFNα-induced TRIM14 transcription suppresses antitumor immunity by recruiting USP14 to inhibit autophagic degradation of PD-L1, indicating that targeting this axis could be an effective immunotherapeutic approach for treating cancer.

NXPH4 mediated by m5C contributes to the malignant characteristics of colorectal cancer via inhibiting HIF1A degradation

OBJECTIVE

Colorectal cancer (CRC) is a form of malignancy that exhibits a comparatively elevated occurrence and fatality rate. Given the relatively slower progress in diagnostic and therapeutic approaches for CRC, there is a need to investigate more accurate and efficient biomarkers.

METHODS

Core regulatory genes were screened using the TCGA database, and the expression of neurexophilin 4 (NXPH4) and its prognostic implications were validated using tissue microarray staining. The assessment of NXPH4 functions involved a range of experiments, including cellular, organoid, and murine models. Furthermore, a regulatory network between m5C, NXPH4, and HIF1A was established through several in vitro experiments.

RESULTS

The overexpression of NXPH4 is associated with unfavorable prognoses in patients with CRC and hepatocellular carcinoma. Additionally, it facilitates the progression of malignant tumors both in laboratory settings and in living organisms of colorectal carcinoma. Our research also reveals that NXPH4 mRNA can avoid degradation through RNautophagy, relying on an m5C-dependent mechanism. Moreover, NXPH4 amplifies the HIF signaling pathway and stabilizes HIF1A by competitively binding to PHD4.

CONCLUSIONS

NXPH4, regulated by m5C, promotes malignant tumor progression and regulates the HIF pathway. Consequently, targeting NXPH4 through molecular therapies could potentially serve as an efficacious therapeutic strategy for the management of CRC exhibiting elevated NXPH4 expression.

ZDHHC7-mediated S-palmitoylation of ATG16L1 facilitates LC3 lipidation and autophagosome formation

Macroautophagy/autophagy is a fundamental cellular catabolic process that delivers cytoplasmic components into double-membrane vesicles called autophagosomes, which then fuse with lysosomes and their contents are degraded. Autophagy recycles cytoplasmic components, including misfolded proteins, dysfunctional organelles and even microbial invaders, thereby playing an essential role in development, immunity and cell death. Autophagosome formation is the main step in autophagy, which is governed by a set of ATG (autophagy related) proteins. ATG16L1 interacts with ATG12-ATG5 conjugate to form an ATG12-ATG5-ATG16L1 complex. The complex acts as a ubiquitin-like E3 ligase that catalyzes the lipidation of MAP1LC3/LC3 (microtubule associated protein 1 light chain 3), which is crucial for autophagosome formation. In the present study, we found that ATG16L1 was subject to S-palmitoylation on cysteine 153, which was catalyzed by ZDHHC7 (zinc finger DHHC-type palmitoyltransferase 7). We observed that re-expressing ATG16L1 but not the S-palmitoylation-deficient mutant ATG16L1C153S rescued a defect in the lipidation of LC3 and the formation of autophagosomes in ATG16L1-KO (knockout) HeLa cells. Furthermore, increasing ATG16L1 S-palmitoylation by ZDHHC7 expression promoted the production of LC3-II, whereas reducing ATG16L1 S-palmitoylation by ZDHHC7 deletion inhibited the LC3 lipidation process and autophagosome formation. Mechanistically, the addition of a hydrophobic 16-carbon palmitoyl group on Cys153 residue of ATG16L1 enhances the formation of ATG16L1-WIPI2B complex and ATG16L1-RAB33B complex on phagophore, thereby facilitating the LC3 lipidation process and autophagosome formation. In conclusion, S-palmitoylation of ATG16L1 is essential for the lipidation process of LC3 and the formation of autophagosomes. Our research uncovers a new regulatory mechanism of ATG16L1 function in autophagy.Abbreviation: ABE: acyl-biotin exchange; ATG: autophagy related; Baf-A1: bafilomycin A1; 2-BP: 2-bromopalmitate; CCD: coiled-coil domain; co-IP: co-immunoprecipitation; CQ: chloroquine; EBSS: Earle's balanced salt solution; HAM: hydroxylamine; KO: knockout; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NP-40: Nonidet P-40; PBS: phosphate-buffered saline; PE: phosphatidylethanolamine; PtdIns3K-C1: class III phosphatidylinositol 3-kinase complex I; PTM: post-translational modification; RAB33B: RAB33B, member RAS oncogene family; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SDS: sodium dodecyl sulfate; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscope; WD: tryptophan and aspartic acid; WIPI2B: WD repeat domain, phosphoinositide interacting 2B; WT: wild-type; ZDHHC: zinc finger DHHC-type.

Autophagy in Disease Onset and Progression

Autophagy is a biological phenomenon whereby components of cells can self-degrade using autophagosomes. During this process, cells can clear dysfunctional organelles or unwanted elements. Autophagy can recycle unnecessary biomolecules into new components or sometimes, even destroy the cells themselves. This cellular process was first observed in 1962 by Keith R. Porter et al. Since then, autophagy has been studied for over 60 years, and much has been learned on the topic. Nevertheless, the process is still not fully understood. It has been proven, for example, that autophagy can be a positive force for maintaining good health by removing older or damaged cells. By contrast, autophagy is also involved in the onset and progression of various conditions caused by pathogenic infections. These diseases generally involve several important organs in the human body, including the liver, kidney, heart, and central nervous system. The regulation of the defects of autophagy defects may potentially be used to treat some diseases. This review comprehensively discusses recent research frontiers and topics of interest regarding autophagy-related diseases.

PD-L1 induces autophagy and primary resistance to EGFR-TKIs in EGFR-mutant lung adenocarcinoma via the MAPK signaling pathway

Resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) is a significant cause of treatment failure and cancer recurrence in non-small cell lung cancer (NSCLC). Approximately 30% of patients with EGFR-activating mutations exhibit primary resistance to EGFR-TKIs. However, the potential mechanisms of primary resistance to EGFR-TKIs remain poorly understood. Recent studies have shown that increased expression of programmed death ligand-1 (PD-L1) is associated with EGFR-TKIs resistance. Therefore, the present study aimed to investigate the mechanism of PD-L1 in primary resistance to EGFR-TKIs in EGFR-mutant lung adenocarcinoma (LUAD) cells. We found that PD-L1 was associated with poor prognosis in patients with EGFR-mutant LUAD, while the combination of EGFR-TKIs with chemotherapy could improve its therapeutic efficacy. In vitro and in vivo experiments revealed that PD-L1 promoted the proliferation and autophagy and inhibited the apoptosis of LUAD cells. Mechanistic studies demonstrated that upregulation of PD-L1 was critical in inducing autophagy through the mitogen-activated protein kinase (MAPK) signaling pathway, which was beneficial for tumor progression and the development of gefitinib resistance. Furthermore, we found that gefitinib combined with pemetrexed could synergistically enhance antitumor efficacy in PD-L1-overexpression LUAD cells. Overall, our study demonstrated that PD-L1 contributed to primary resistance to EGFR-TKIs in EGFR-mutant LUAD cells, which may be mediated by inducing autophagy via the MAPK signaling pathway. These findings not only help improve the prognosis of patients with EGFR-mutant LUAD but also provide a reference for the research of other cancer types.

Enhancing the Antitumor Efficacy of Oncolytic Adenovirus Through Sonodynamic Therapy-Augmented Virus Replication

The therapeutic efficacy of oncolytic adenoviruses (OAs) relies on efficient viral transduction and replication. However, the limited expression of coxsackie-adenovirus receptors in many tumors, along with the intracellular antiviral signaling, poses significant obstacles to OA infection and oncolysis. Here, we present sonosensitizer-armed OAs (saOAs) that potentiate the antitumor efficacy of oncolytic virotherapy through sonodynamic therapy-augmented virus replication. The saOAs could not only efficiently infect tumor cells via transferrin receptor-mediated endocytosis but also exhibit enhanced viral replication and tumor oncolysis under ultrasound irradiation. We revealed that the sonosensitizer loaded on the viruses induced the generation of ROS within tumor cells, which triggered JNK-mediated autophagy, ultimately leading to the enhanced viral replication. In mouse models of malignant melanoma, the combination of saOAs and sonodynamic therapy elicited a robust antitumor immune response, resulting in significant inhibition of melanoma growth and improved host survival. This work highlights the potential of sonodynamic therapy in enhancing the effectiveness of OAs and provides a promising platform for fully exploiting the antitumor efficacy of oncolytic virotherapy.

JD-02, a novel Hsp90 inhibitor, induces ROS/SRC axis-dependent cytoprotective autophagy in colorectal cancer cells

Heat shock protein 90 (Hsp90) is a tumor marker that accelerates cancer growth by disrupting protein homeostasis. However, concerns such as low clinical efficacy and drug resistance continue to be obstacles to the successful marketing of Hsp90 inhibitors. The cytoprotective function of autophagy has been identified as one of the mechanisms by which tumor cells gain resistance to chemotherapy. JD-02 was identified as a new Hsp90 inhibitor that suppressed colorectal cancer (CRC) growth by lowering client protein levels in vivo and in vitro. We found that JD-02 increased cellular autophagy, which inhibited apoptosis. JD-02 enhanced cytoprotective autophagy and regulated apoptotic suppression by increasing intracellular reactive oxygen species and inhibiting SRC protein levels, as demonstrated by quantitative proteomics, bioinformatic analysis, western blotting, and flow cytometry. This effect was reversed by autophagy inhibition. Therefore, due to the synergistic effects of Hsp90 and autophagy inhibitors in efficiently activating apoptotic pathways, they could potentially serve as promising therapeutic options for CRC.

Lysosomes in Cancer-At the Crossroad of Good and Evil

Although it has been known for decades that lysosomes are central for degradation and recycling in the cell, their pivotal role as nutrient sensing signaling hubs has recently become of central interest. Since lysosomes are highly dynamic and in constant change regarding content and intracellular position, fusion/fission events allow communication between organelles in the cell, as well as cell-to-cell communication via exocytosis of lysosomal content and release of extracellular vesicles. Lysosomes also mediate different forms of regulated cell death by permeabilization of the lysosomal membrane and release of their content to the cytosol. In cancer cells, lysosomal biogenesis and autophagy are increased to support the increased metabolism and allow growth even under nutrient- and oxygen-poor conditions. Tumor cells also induce exocytosis of lysosomal content to the extracellular space to promote invasion and metastasis. However, due to the enhanced lysosomal function, cancer cells are often more susceptible to lysosomal membrane permeabilization, providing an alternative strategy to induce cell death. This review summarizes the current knowledge of cancer-associated alterations in lysosomal structure and function and illustrates how lysosomal exocytosis and release of extracellular vesicles affect disease progression. We focus on functional differences depending on lysosomal localization and the regulation of intracellular transport, and lastly provide insight how new therapeutic strategies can exploit the power of the lysosome and improve cancer treatment.

Lysosomes as coordinators of cellular catabolism, metabolic signalling and organ physiology

Every cell must satisfy basic requirements for nutrient sensing, utilization and recycling through macromolecular breakdown to coordinate programmes for growth, repair and stress adaptation. The lysosome orchestrates these key functions through the synchronised interplay between hydrolytic enzymes, nutrient transporters and signalling factors, which together enable metabolic coordination with other organelles and regulation of specific gene expression programmes. In this Review, we discuss recent findings on lysosome-dependent signalling pathways, focusing on how the lysosome senses nutrient availability through its physical and functional association with mechanistic target of rapamycin complex 1 (mTORC1) and how, in response, the microphthalmia/transcription factor E (MiT/TFE) transcription factors exert feedback regulation on lysosome biogenesis. We also highlight the emerging interactions of lysosomes with other organelles, which contribute to cellular homeostasis. Lastly, we discuss how lysosome dysfunction contributes to diverse disease pathologies and how inherited mutations that compromise lysosomal hydrolysis, transport or signalling components lead to multi-organ disorders with severe metabolic and neurological impact. A deeper comprehension of lysosomal composition and function, at both the cellular and organismal level, may uncover fundamental insights into human physiology and disease.

In vivo CRISPR knockout screen identifies p47 as a suppressor of HER2+ breast cancer metastasis by regulating NEMO trafficking and autophagy flux

Autophagy is a conserved cellular process, and its dysfunction is implicated in cancer and other diseases. Here, we employ an in vivo CRISPR screen targeting genes implicated in the regulation of autophagy to identify the Nsfl1c gene encoding p47 as a suppressor of human epidermal growth factor receptor 2 (HER2)+ breast cancer metastasis. p47 ablation specifically increases metastasis without promoting primary mammary tumor growth. Analysis of human breast cancer patient databases and tissue samples indicates a correlation of lower p47 expression levels with metastasis and decreased survival. Mechanistic studies show that p47 functions in the repair of lysosomal damage for autophagy flux and in the endosomal trafficking of nuclear factor κB essential modulator for lysosomal degradation to promote metastasis. Our results demonstrate a role and mechanisms of p47 in the regulation of breast cancer metastasis. They highlight the potential to exploit p47 as a suppressor of metastasis through multiple pathways in HER2+ breast cancer cells.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

MicroRNA-183 cluster: a promising biomarker and therapeutic target in gastrointestinal malignancies

Small non-coding RNAs (microRNA, miR), powerful epigenetic regulators, were found involved in the regulation of most biological functions via post-translational inhibition of protein expression. Increased expression of pro-oncogenic miRs (known as miR cancer biomarkers) and inhibition of pro-apoptotic miR expression have been demonstrated in different tumors. The recently identified miR-183 was found implicated in gastrointestinal tumor metabolism regulation. Elevated miR-183 expression and cancer-promoting effects were reported in esophageal and colorectal cancers, which was partially contradicted by controversial data observed in gastric cancers. Anti-cancer effect of miR-183 in gastric cancer cells was associated with the Bim-1 and Ezrin genes regulation. Many studies indicated that miR-183 can inhibit tumor suppressor genes in most cell lines, promoting tumor cell proliferation and migration. Increased miR-183 level results in the downregulation of FOXO1, PDCD4, and other tumor suppressor genes in gastrointestinal tumor cells. MiR-183 also influences the signaling of PI3K/AKT/mTOR, Wnt/β-catenin, and Bcl-2/p53 signaling pathways. Mir-183 inhibits apoptosis and autophagy, and promotes epithelial-to-mesenchymal transition, cancer cell proliferation, and migration. Accordingly, gastrointestinal cancer occurrence, development of chemoradiotherapy resistance, recurrence/metastasis, and prognosis were associated with miR-183 expression. The current study assessed reported miR-183 functions and signaling, providing new insights for the diagnosis and treatment of gastrointestinal malignancies.

Exploiting autophagy balance in T and NK cells as a new strategy to implement adoptive cell therapies

Autophagy is an essential cellular homeostasis pathway initiated by multiple stimuli ranging from nutrient deprivation to viral infection, playing a key role in human health and disease. At present, a growing number of evidence suggests a role of autophagy as a primitive innate immune form of defense for eukaryotic cells, interacting with components of innate immune signaling pathways and regulating thymic selection, antigen presentation, cytokine production and T/NK cell homeostasis. In cancer, autophagy is intimately involved in the immunological control of tumor progression and response to therapy. However, very little is known about the role and impact of autophagy in T and NK cells, the main players in the active fight against infections and tumors. Important questions are emerging: what role does autophagy play on T/NK cells? Could its modulation lead to any advantages? Could specific targeting of autophagy on tumor cells (blocking) and T/NK cells (activation) be a new intervention strategy? In this review, we debate preclinical studies that have identified autophagy as a key regulator of immune responses by modulating the functions of different immune cells and discuss the redundancy or diversity among the subpopulations of both T and NK cells in physiologic context and in cancer.

Autophagy impairment in human bile duct carcinoma cells

Bile duct epithelial cells, named cholangiocytes, may undergo a neoplastic transformation leading to cholangiocarcinoma. The role autophagy plays in cancer is still debated and few information are available in cholangiocarcinoma. We report in vitro data, at least in part validated in vivo,i ndicating that autophagy is impaired in intrahepatic cholangiocarcinoma cells, as compared to healthy cholangiocytes, evaluated through LC3II and p62 Western blot analyses. Autophagy impairment was found to be associated with low expression of TFEB protein and high expression of three proteins i.e., c-FLIP, caspase-10 and cleaved BCLAF-1, as compared to healthy cholangiocytes. We highlight biological effects of autophagy impairment in cholangiocarcinoma showing that autophagy induction, via rapamycin, as well as caspase inhibition, via Q-VD-OPh, are able to reduce proliferation marker PCNA level, colony size and protein content of cultured cholangiocarcinoma cells. The increased protein expression of p62, c-FLIP, caspase-10 observed in vitro in cholangiocarcinoma cells was paralleled by significant increase at gene expression levels in vivo; in fact, significant increase of transcript levels of p62, c-FLIP and caspase-10 was observed in 34 biopsies from human cholangiocarcinoma patients compared to 9 biopsies from 9 healthy controls, as reported in the GEPIA2 public database. The significant increase of p62 level in cholangiocarcinoma was found as a relatively uncommon finding in solid cancers, since it was also found in only 7 cancer types out of 31 cancer types investigated, including melanoma and hepatocarcinoma. In conclusion, we present data suggesting a molecular machinery controlling autophagy in cholangiocytes and autophagy impairment in cholangiocarcinoma.