Metastatic outgrowth via the two-way interplay of autophagy and metabolism

Mechanistic insights and therapeutic strategies for targeting autophagy in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is characterised by early metastasis and resistance to anti-cancer therapy, leading to an overall poor prognosis. Macroautophagy (hereinafter referred to as autophagy) is a conserved cellular homeostasis mechanism that degrades various cargoes (e.g., proteins, organelles, and pathogens) mainly playing a role in promoting survival under environmental stress. Autophagy is an essential defense mechanism against PDAC initiation, acting on multiple levels to maintain cellular and tissue homeostasis. However, autophagy is also intimately involved in the molecular mechanisms driving PDAC progression, facilitating the adaptation of cancer cells to the tumor microenvironment's harsh conditions. In this review, we examine the complex role of autophagy in PDAC and assess the potential of modulating autophagy as a therapeutic strategy. By reviewing current research and clinical trials, we seek to elucidate how targeting autophagy can disrupt PDAC tumor survival mechanisms, enhance the efficacy of existing treatments, and ultimately improve patient outcomes.

The involvement of circRNAs in molecular processes and their potential use in therapy and diagnostics for glioblastoma

Glioblastoma, a type of brain tumor, is well-known for its aggressive nature and can affect individuals of all ages. Glioblastoma continues to be a difficult cancer to manage because of various resistance mechanisms. The blood-brain barrier restricts the delivery of drugs, and the heterogeneity of tumors, along with overlapping signaling pathways, complicates its effective treatment. Patients diagnosed with glioblastoma typically survive for no more than 2 years. Innovative therapies and early diagnostic tools for glioblastoma are essential. Circular RNAs have emerged as significant contributors to glioblastoma, and influence cancer mechanisms such as cell growth, death, invasion, and resistance to treatment. The circRNAs presence makes them essential candidates for treatment and practical diagnostic tools for glioblastoma. This review highlights the therapeutic approaches and diagnostic potential of circRNAs and explores their role in the molecular mechanisms underlying glioblastoma.

NRF-mediated autophagy and UPR: Exploring new avenues to overcome cancer chemo-resistance

The development of chemo-resistance remains a significant hurdle in effective cancer therapy. NRF1 and NRF2, key regulators of redox homeostasis, play crucial roles in the cellular response to oxidative stress, with implications for both tumor growth and resistance to chemotherapy. This study delves into the dualistic role of NRF2, exploring its protective functions in normal cells and its paradoxical support of tumor survival and drug resistance in cancerous cells. We investigate the interplay between the PERK/NRF signaling pathway, ER stress, autophagy, and the unfolded protein response, offering a mechanistic perspective on how these processes contribute to chemoresistance. Our findings suggest that targeting NRF signaling pathways may offer new avenues for overcoming resistance to chemotherapeutic agents, highlighting the importance of a nuanced approach to redox regulation in cancer treatment. This research provides a molecular basis for the development of NRF-targeted therapies, potentially enhancing the efficacy of existing cancer treatments and offering hope for more effective management of resistant tumors.

Assessment of Stiffness-Dependent Autophagosome Formation and Apoptosis in Embryonal Rhabdomyosarcoma Tumor Cells

Remodeling of the extracellular matrix (ECM) eventually causes the stiffening of tumors and changes to the microenvironment. The stiffening alters the biological processes in cancer cells due to altered signaling through cell surface receptors. Autophagy, a key catabolic process in normal and cancer cells, is thought to be involved in mechano-transduction and the level of autophagy is probably stiffness-dependent. Here, we provide a methodology to study the effect of matrix stiffness on autophagy in embryonal rhabdomyosarcoma cells. To mimic stiffness, we seeded cells on GelMA hydrogel matrices with defined stiffness and evaluated autophagy-related endpoints. We also evaluated autophagy-dependent pathways, apoptosis, and cell viability. Specifically, we utilized immunocytochemistry and confocal microscopy to track autophagosome formation through LC3 lipidation. This approach suggests that the use of GelMA hydrogels with defined stiffness represents a novel method to evaluate the role of autophagy in embryonal rhabdomyosarcoma and other cancer cells.

Evaluation of Mitochondrial Phagy (Mitophagy) in Human Non-small Adenocarcinoma Tumor Cells

Non-small cell lung cancer (NSCLC) is a predominant form of lung cancer characterized by its aggressive nature and high mortality rate, primarily due to late-stage diagnosis and metastatic spread. Recent studies underscore the pivotal role of mitophagy, a selective form of autophagy targeting damaged or superfluous mitochondria, in cancer biology, including NSCLC. Mitophagy regulation may influence cancer cell survival, proliferation, and metastasis by modulating mitochondrial quality and cellular energy homeostasis. Herein, we present a comprehensive methodology developed in our laboratory for the evaluation of mitophagy in NSCLC tumor cells. Utilizing a combination of immunoblotting, immunocytochemistry, and fluorescent microscopy, we detail the steps to quantify early and late mitophagy markers and mitochondrial dynamics. Our findings highlight the potential of targeting mitophagy pathways as a novel therapeutic strategy in NSCLC, offering insights into the complex interplay between mitochondrial dysfunction and tumor progression. This study not only sheds light on the significance of mitophagy in NSCLC but also establishes a foundational approach for its investigation, paving way for future research in this critical area of cancer biology.

Assessment of Autophagy in Leishmania Parasites

Leishmaniasis is a neglected tropical disease caused by numerous species of Leishmania parasites, including Leishmania major. The parasite is transmitted by several species of sandfly vectors and infects myeloid cells leading to a myriad of inflammatory responses, immune dysregulations, and disease manifestations. Every cell undergoes autophagy, a self-regulated degradative process that permits the cells to recycle damaged or worn-out organelles in order to maintain cellular health and homeostasis. Studies have shown that Leishmania modulates their host cell autophagic machinery and there are indications that the parasite-specific autophagic processes may be valuable for parasite virulence and survival. However, the role of autophagy in Leishmania is inconclusive because of the limited tools available to study the Leishmania-specific autophagic machinery. Here, we describe methods to study and definitively confirm autophagy in Leishmania major. Transmission electron microscopy (TEM) allowed us to visualize Leishmania autophagosomes, especially those containing damaged mitochondrial content, as well as dividing mitochondria with ongoing fusion/fission processes. Flow cytometry enabled us to identify the amount of acridine orange dye accumulating in the acidic vacuolar compartments in Leishmania major by detecting fluorescence in the red laser when autophagic inhibitors or enhancers were included. These methods will advance studies that aim to understand autophagic regulation in Leishmania parasites that could provide insights into developing improved therapeutic targets against leishmaniasis.

Highlighting roles of autophagy in human diseases: a perspective from single-cell RNA sequencing analyses

Autophagy, the lysosome-driven breakdown of intracellular components, is pivotal in regulating eukaryotic cellular processes and maintaining homeostasis, making it physiologically important even under normal conditions. Cellular mechanisms involving autophagy include the response to nutrient deprivation, intracellular quality control, early development, and cell differentiation. Despite its established health significance, the role of autophagy in cancer and other diseases remains complex and not fully understood. A comprehensive understanding of autophagy is crucial to facilitate the development of novel therapies and drugs that can protect and improve human health. High-throughput technologies, such as single-cell RNA sequencing (scRNA-seq), have enabled researchers to study transcriptional landscapes at single-cell resolution, significantly advancing our knowledge of autophagy pathways across diverse physiological and pathological contexts. This review discusses the latest advances in scRNA-seq for autophagy research and highlights its potential in the molecular characterization of various diseases.

MiR-29a-laden extracellular vesicles efficiently induced apoptosis through autophagy blockage in HCC cells

BACKGROUND

In spite of significant advancements in theraputic modalities for hepatocellular carcinoma (HCC), there is still a high annual mortality rate with a rising incidence. Major challenges in the HCC clinical managment are related to the development of therapy resistance, and evasion of tumor cells apoptosis which leading unsatisfactory outcomes in HCC patients. Previous investigations have shown that autophagy plays crucial role in contributing to drug resistance development in HCC. Although, miR-29a is known to counteract authophagy, increasing evidence revealed a down-regulation of miR-29a in HCC patients which correlates with poor prognosis. Beside, evidences showed that miR-29a serves as a negative regulator of autophagy in other cancers. In the current study, we aim to investigate the impact of miR-29a on the autophagy and apoptosis in HCC cells using extracellular vesicles (EVs) as a natural delivery system given their potential in the miRNA delivery both in vitro and in vivo.

METHOD

Human Wharton's Jelly mesenchymal stromal cell-derived extracellular vesicles were lately isolated through 20,000 or 110,000 × g centrifugation (EV20K or EV110K, respectively), characterized by western blot (WB), scanning electron microscopy (SEM), and dynamic light scattering (DLS). miR-29a was subsequently loaded into these EVs and its loading efficiency was evaluated via RT-qPCR. Comprehensive in vitro and in vivo assessments were then performed on Huh-7 and HepG2 cell lines.

RESULTS

EV20K-miR-29a treatment significantly induces cell apoptosis and reduces both cell proliferation and colony formation in Huh-7 and HepG2 cell lines. In addition, LC3-II/LC3-I ratio was increased while the expression of key autophagy regulators TFEB and ATG9A were downregulated by this treatment. These findings suggest an effective blockade of autophagy by EV20K-miR-29a leading to apoptosis in the HCC cell lines through concomitant targeting of critical mediators within each pathway.

Metabolic reprogramming in tumor immune microenvironment: Impact on immune cell function and therapeutic implications

Understanding of the metabolic reprogramming has revolutionized our insights into tumor progression and potential treatment. This review concentrates on the aberrant metabolic pathways in cancer cells within the tumor microenvironment (TME). Cancer cells differ from normal cells in their metabolic processing of glucose, amino acids, and lipids in order to adapt to heightened biosynthetic and energy needs. These metabolic shifts, which crucially alter lactic acid, amino acid and lipid metabolism, affect not only tumor cell proliferation but also TME dynamics. This review also explores the reprogramming of various immune cells in the TME. From a therapeutic standpoint, targeting these metabolic alterations represents a novel cancer treatment strategy. This review also discusses approaches targeting the regulation of metabolism of different nutrients in tumor cells and influencing the tumor microenvironment to enhance the immune response. In summary, this review summarizes metabolic reprogramming in cancer and its potential as a target for innovative therapeutic strategies, offering fresh perspectives on cancer treatment.

Therapeutic and diagnostic applications of exosomes in colorectal cancer

Exosomes play a key role in colorectal cancer (CRC) related processes. This review explores the various functions of exosomes in CRC and their potential as diagnostic markers, therapeutic targets, and drug delivery vehicles. Exosomal long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) significantly influence CRC progression. Specific exosomal lncRNAs are linked to drug resistance and tumor growth, respectively, highlighting their therapeutic potential. Similarly, miRNAs like miR-21, miR-10b, and miR-92a-3p, carried by exosomes, contribute to chemotherapy resistance by altering signaling pathways and gene expression in CRC cells. The review also discusses exosomes' utility in CRC diagnosis. Exosomes from cancer cells have distinct molecular signatures compared to healthy cells, making them reliable biomarkers. Specific exosomal lncRNAs (e.g., CRNDE-h) and miRNAs (e.g., miR-17-92a) have shown effectiveness in early CRC detection and monitoring of treatment responses. Furthermore, exosomes show promise as vehicles for targeted drug delivery. The potential of mesenchymal stem cell (MSC)-derived exosomes in CRC treatment is also noted, with their role varying from promoting to inhibiting tumor progression. The application of multi-omics approaches to exosome research is highlighted, emphasizing the potential for discovering novel CRC biomarkers through comprehensive genomic, transcriptomic, proteomic, and metabolomic analyses. The review also explores the emerging field of exosome-based vaccines, which utilize exosomes' natural properties to elicit strong immune responses. In conclusion, exosomes represent a promising frontier in CRC research, offering new avenues for diagnosis, treatment, and prevention. Their unique properties and versatile functions underscore the need for continued investigation into their clinical applications and underlying mechanisms.

Recent Advances on Mutant p53: Unveiling Novel Oncogenic Roles, Degradation Pathways, and Therapeutic Interventions

The p53 protein is the master regulator of cellular integrity, primarily due to its tumor-suppressing functions. Approximately half of all human cancers carry mutations in the TP53 gene, which not only abrogate the tumor-suppressive functions but also confer p53 mutant proteins with oncogenic potential. The latter is achieved through so-called gain-of-function (GOF) mutations that promote cancer progression, metastasis, and therapy resistance by deregulating transcriptional networks, signaling pathways, metabolism, immune surveillance, and cellular compositions of the microenvironment. Despite recent progress in understanding the complexity of mutp53 in neoplastic development, the exact mechanisms of how mutp53 contributes to cancer development and how they escape proteasomal and lysosomal degradation remain only partially understood. In this review, we address recent findings in the field of oncogenic functions of mutp53 specifically regarding, but not limited to, its implications in metabolic pathways, the secretome of cancer cells, the cancer microenvironment, and the regulating scenarios of the aberrant proteasomal degradation. By analyzing proteasomal and lysosomal protein degradation, as well as its connection with autophagy, we propose new therapeutical approaches that aim to destabilize mutp53 proteins and deactivate its oncogenic functions, thereby providing a fundamental basis for further investigation and rational treatment approaches for TP53-mutated cancers.

Bitter Taste Receptor T2R14 and Autophagy Flux in Gingival Epithelial Cells

Macroautophagy (hereafter autophagy) is a lysosomal degradation pathway that functions in nutrient recycling and as a mechanism of innate immunity. Previously, we reported a novel host-bacteria interaction between cariogenic S. mutans and bitter taste receptor (T2R14) in gingival epithelial cells (GECs), leading to an innate immune response. Further, S. mutans might be using the host immune system to inhibit other Gram-positive bacteria, such as S. aureus. To determine whether these bacteria exploit the autophagic machinery of GEC, it is first necessary to evaluate the role of T2R14 in modulating autophagic flux. So far, the role of T2R14 in the regulation of autophagy is not well characterized. Therefore, in this study, for the first time, we report that T2R14 downregulates autophagy flux in GECs, and T2R14 knockout increases acidic vacuoles. However, the treatments of GEC WT with a T2R14 agonist and antagonist did not lead to a significant change in acidic vacuole formation. Transmission electron microscopy morphometric results also suggested an increased number of autophagic vesicles in T2R14-knockout GEC. Further, our results suggest that S. mutans competence stimulating peptide CSP-1 showed robust intracellular calcium release and this effect is both T2R14- and autophagy protein 7-dependent. In this study, we provide the first evidence that T2R14 modulates autophagy flux in GEC. The results of the current study could help in identifying the impact of T2R in regulation of the immuno-microenvironment of GEC and subsequently oral health.

The obesity-autophagy-cancer axis: Mechanistic insights and therapeutic perspectives

Autophagy, a self-degradative process vital for cellular homeostasis, plays a significant role in adipose tissue metabolism and tumorigenesis. This review aims to elucidate the complex interplay between autophagy, obesity, and cancer development, with a specific emphasis on how obesity-driven changes affect the regulation of autophagy and subsequent implications for cancer risk. The burgeoning epidemic of obesity underscores the relevance of this research, particularly given the established links between obesity, autophagy, and various cancers. Our exploration delves into hormonal influence, notably INS (insulin) and LEP (leptin), on obesity and autophagy interactions. Further, we draw attention to the latest findings on molecular factors linking obesity to cancer, including hormonal changes, altered metabolism, and secretory autophagy. We posit that targeting autophagy modulation may offer a potent therapeutic approach for obesity-associated cancer, pointing to promising advancements in nanocarrier-based targeted therapies for autophagy modulation. However, we also recognize the challenges inherent to these approaches, particularly concerning their precision, control, and the dual roles autophagy can play in cancer. Future research directions include identifying novel biomarkers, refining targeted therapies, and harmonizing these approaches with precision medicine principles, thereby contributing to a more personalized, effective treatment paradigm for obesity-mediated cancer.