Macrophage ABHD5 Suppresses NFκB-Dependent Matrix Metalloproteinase Expression and Cancer Metastasis

Association between Metabolic Reprogramming and Immune Regulation in Digestive Tract Tumors

BACKGROUND

The cancers of the digestive tract, including colorectal cancer (CRC), gastric cancer, and esophageal cancer, are part of the most common cancers as well as one of the most important leading causes of cancer death worldwide.

SUMMARY

Despite the emergence of immune checkpoint inhibitors (e.g., anti-CTLA-4 and anti-PD-1/PD-L1) in the past decade, offering renewed optimism in cancer treatment, only a fraction of patients derive benefit from these therapies. This limited efficacy may stem from tumor heterogeneity and the impact of metabolic reprogramming on both tumor cells and immune cells within the tumor microenvironment (TME). The metabolic reprogramming of glucose, lipids, amino acids, and other nutrients represents a pivotal hallmark of cancer, serving to generate energy, reducing equivalent and biological macromolecule, thereby fostering tumor proliferation and invasion. Significantly, the metabolic reprogramming of tumor cells can orchestrate changes within the TME, rendering patients unresponsive to immunotherapy.

KEY MESSAGES

In this review, we predominantly encapsulate recent strides on metabolic reprogramming among digestive tract cancer, especially CRC, in the TME with a focus on how these alterations influence anti-tumor immunity. Additionally, we deliberate on potential strategies to address these abnormities in metabolic pathways and the viability of combined therapy within the realm of anti-cancer immunotherapy.

Elevated Kallistatin promotes the occurrence and progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, and the development of non-alcoholic steatohepatitis (NASH) might cause irreversible hepatic damage. Hyperlipidemia (HLP) is the leading risk factor for NAFLD. This study aims to illuminate the causative contributor and potential mechanism of Kallistatin (KAL) mediating HLP to NAFLD. 221 healthy control and 253 HLP subjects, 62 healthy control and 44 NAFLD subjects were enrolled. The plasma KAL was significantly elevated in HLP subjects, especially in hypertriglyceridemia (HTG) subjects, and positively correlated with liver injury. Further, KAL levels of NAFLD patients were significantly up-regulated. KAL transgenic mice induced hepatic steatosis, inflammation, and fibrosis with time and accelerated inflammation development in high-fat diet (HFD) mice. In contrast, KAL knockout ameliorated steatosis and inflammation in high-fructose diet (HFruD) and methionine and choline-deficient (MCD) diet-induced NAFLD rats. Mechanistically, KAL induced hepatic steatosis and NASH by down-regulating adipose triglyceride lipase (ATGL) and comparative gene identification 58 (CGI-58) by LRP6/Gɑs/PKA/GSK3β pathway through down-regulating peroxisome proliferator-activated receptor γ (PPARγ) and up-regulating kruppel-like factor four (KLF4), respectively. CGI-58 is bound to NF-κB p65 in the cytoplasm, and diminishing CGI-58 facilitated p65 nuclear translocation and TNFα induction. Meanwhile, hepatic CGI-58-overexpress reverses NASH in KAL transgenic mice. Further, free fatty acids up-regulated KAL against thyroid hormone in hepatocytes. Moreover, Fenofibrate, one triglyceride-lowering drug, could reverse hepatic steatosis by down-regulating KAL. These results demonstrate that elevated KAL plays a crucial role in the development of HLP to NAFLD and may be served as a potential preventive and therapeutic target.

Roles of lncRNAs in NF-κB-Mediated Macrophage Inflammation and Their Implications in the Pathogenesis of Human Diseases

Over the past century, molecular biology's focus has transitioned from proteins to DNA, and now to RNA. Once considered merely a genetic information carrier, RNA is now recognized as both a vital element in early cellular life and a regulator in complex organisms. Long noncoding RNAs (lncRNAs), which are over 200 bases long but do not code for proteins, play roles in gene expression regulation and signal transduction by inducing epigenetic changes or interacting with various proteins and RNAs. These interactions exhibit a range of functions in various cell types, including macrophages. Notably, some macrophage lncRNAs influence the activation of NF-κB, a crucial transcription factor governing immune and inflammatory responses. Macrophage NF-κB is instrumental in the progression of various pathological conditions including sepsis, atherosclerosis, cancer, autoimmune disorders, and hypersensitivity. It orchestrates gene expression related to immune responses, inflammation, cell survival, and proliferation. Consequently, its malfunction is a key contributor to the onset and development of these diseases. This review aims to summarize the function of lncRNAs in regulating NF-κB activity in macrophage activation and inflammation, with a particular emphasis on their relevance to human diseases and their potential as therapeutic targets. The insights gained from studies on macrophage lncRNAs, as discussed in this review, could provide valuable knowledge for the development of treatments for various pathological conditions involving macrophages.

NF-κB: Governing Macrophages in Cancer

Tumor-associated macrophages (TAMs) are the major component of the tumor microenvironment (TME), where they sustain tumor progression and or-tumor immunity. Due to their plasticity, macrophages can exhibit anti- or pro-tumor functions through the expression of different gene sets leading to distinct macrophage phenotypes: M1-like or pro-inflammatory and M2-like or anti-inflammatory. NF-κB transcription factors are central regulators of TAMs in cancers, where they often drive macrophage polarization toward an M2-like phenotype. Therefore, the NF-κB pathway is an attractive therapeutic target for cancer immunotherapy in a wide range of human tumors. Hence, targeting NF-κB pathway in the myeloid compartment is a potential clinical strategy to overcome microenvironment-induced immunosuppression and increase anti-tumor immunity. In this review, we discuss the role of NF-κB as a key driver of macrophage functions in tumors as well as the principal strategies to overcome tumor immunosuppression by targeting the NF-κB pathway.

Early diagnosis for the onset of peri-implantitis based on artificial neural network

The aim of this study is to construct an artificial neural network (ANN) based on bioinformatic analysis to enable early diagnosis of peri-implantitis (PI). PI-related datasets were retrieved from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and functional enrichment analyses were performed between PI and the control group. Furthermore, the infiltration of 22 immune cells in PI was analyzed using CIBERSORT. Hub genes were identified with random forest (RF) classification. The ANN model was then constructed for early diagnosis of PI. A total of 1,380 DEGs were identified. Enrichment analysis revealed the involvement of neutrophil-mediated immunity and the NF-kappa B signaling pathway in PI. Additionally, higher proportion of naive B cells, activated memory CD4 T cells, activated NK cells, M0 macrophages, M1 macrophages, and neutrophils were observed in the soft tissues surrounding PI. From the RF analysis, 13 hub genes (ST6GALNAC4, MTMR11, SKAP2, AKR1B1, PTGS2, CHP2, CPEB2, SYT17, GRIP1, IL10, RAB8B, ABHD5, and IGSF6) were selected. Subsequently, the ANN model for early diagnosis of PI was constructed with high performance. We identified 13 hub genes and developed an ANN model that accurately enables early diagnosis of PI.

Lipid Metabolic Regulatory Crosstalk Between Cancer Cells and Tumor-Associated Macrophages

In the tumor microenvironment, tumor-associated macrophages (TAMs) are one of the most abundant cell populations, playing key roles in tumorigenesis, chemoresistance, immune evasion, and metastasis. There is an important interaction between TAMs and cancer cells: on the one hand, tumors control the function of infiltrating macrophages, contributing to reprogramming of TAMs, and on the other hand, TAMs affect the growth of cancer cells. This review focuses on lipid metabolism changes in the complex relationship between cancer cells and TAMs. We discuss how lipid metabolism in cancer cells affects macrophage phenotypic and metabolic changes and, subsequently, how altered lipid metabolism of TAMs influences tumor progression. Identifying the metabolic changes that influence the complex interaction between tumor cells and TAMs is also an important step in exploring new therapeutic approaches that target metabolic reprogramming of immune cells to enhance their tumoricidal potential and bypass therapy resistance. Our work may provide new targets for antitumor therapies.

Major regulators of the multi-step metastatic process are potential therapeutic targets for breast cancer management

Metastasis is a multi-step process that leads to the dissemination of tumor cells to new sites and, consequently, to multi-organ neoplasia. Although most lethal breast cancer cases are related to metastasis occurrence, little is known about the dysregulation of each step, and clinicians still lack reliable therapeutic targets for metastasis impairment. To fill these gaps, we constructed and analyzed gene regulatory networks for each metastasis step (cell adhesion loss, epithelial-to-mesenchymal transition, and angiogenesis). Through topological analysis, we identified E2F1, EGR1, EZH2, JUN, TP63, and miR-200c-3p as general hub-regulators, FLI1 for cell-adhesion loss specifically, and TRIM28, TCF3, and miR-429 for angiogenesis. Applying the FANMOD algorithm, we identified 60 coherent feed-forward loops regulating metastasis-related genes associated with distant metastasis-free survival prediction. miR-139-5p, miR-200c-3p, miR-454-3p, and miR-1301-3p, among others, were the FFL's mediators. The expression of the regulators and mediators was observed to impact overall survival and to go along with metastasis occurrence. Lastly, we selected 12 key regulators and observed that they are potential therapeutic targets for canonical and candidate antineoplastics and immunomodulatory drugs, like trastuzumab, goserelin, and calcitriol. Our results highlight the relevance of miRNAs in mediating feed-forward loops and regulating the expression of metastasis-related genes. Altogether, our results contribute to understanding the multi-step metastasis complexity and identifying novel therapeutic targets and drugs for breast cancer management.

Increased OIT3 in macrophage promotes PD-L1 expression and hepatocellular carcinogenesis via NF-κB signaling

Oncoprotein-induced transcript 3 (OIT3) facilitates macrophage M2 polarization and hepatocellular carcinoma (HCC) progression, however, whether OIT3 regulates tumor immunity remains largely unknown. Here we found that OIT3 was upregulated in HCC-associated macrophages, which inhibited CD4⁺ and CD8⁺ T-cell infiltration in the tumor microenvironment (TME). Mechanistically, OIT3 increased the expression of PD-L1 on tumor-associated macrophages (TAMs) by activating NF-κB signaling, blockade of NF-κB reversed the immunosuppressive activity of TAMs and dampens HCC tumorigenesis. Our findings provide the molecular basis for OIT3 enhancing tumor immunosuppression and highlighted a potential therapeutic strategy for targeting the TAMs of HCC.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Lipid metabolism in tumor immunology and immunotherapy

Lipids are a diverse class of biomolecules that have been implicated in cancer pathophysiology and in an array of immune responses, making them potential targets for improving immune responsiveness. Lipid and lipid oxidation also can affect tumor progression and response to treatment. Although their importance in cellular functions and their potential as cancer biomarkers have been explored, lipids have yet to be extensively investigated as a possible form of cancer therapy. This review explores the role of lipids in cancer pathophysiology and describes how further understanding of these macromolecules could prompt novel treatments for cancer.

Opportunities and challenges of neoadjuvant targeted therapy in nonsmall cell lung cancer

PURPOSE OF REVIEW

The aim of this study is to summarize the completed and ongoing clinical trials of neoadjuvant targeted therapy, discuss tolerability and efficacy, and explain the role of neoadjuvant targeted therapy in patients with resectable nonsmall cell lung cancer (NSCLC). At the same time, the existing challenges are presented, including assessment methods, biomarkers, surrogate endpoints and so on. We also put forward our views on possible ways to make improvements and establish neoadjuvant therapy a standard treatment in resectable NSCLC.

RECENT FINDINGS

The mortality of lung cancer has decreased in the last 10 years, which can partly be attributed to advancement of targeted therapy. Targeted therapy has become the first-line treatment for patients with advanced mutation gene positive NSCLC, achieving the effect of prolonging overall survival (OS). Compared with chemotherapy, targeted therapy is associated with good tolerability and high response rate. Neoadjuvant targeted therapy has emerged in recent years and attracted attention of researchers. Early findings proved that neoadjuvant targeted therapy alone can improve patients' disease-free survival (DFS) and the efficacy of combining with other forms of neoadjuvant therapy is also being explored by researchers.

SUMMARY

Neoadjuvant targeted therapy is playing an important role in NSCLC and worth more in-depth research.

Extracellular vesicles from colorectal cancer cells promote metastasis via the NOD1 signalling pathway

Pattern-recognition receptors (PRRs) have been shown to promote tumour metastasis via sensing tumour cell-derived small extracellular vesicles (EVs). Nucleotide-binding oligomerisation domain 1 (NOD1), a cytoplasmic PRR, plays a role in colorectal cancer (CRC) by detecting bacterial products. However, the precise mechanisms underlying the effects of NOD1, following identification of CRC cell-derived EVs (CRC-EVs), to potentiate CRC liver metastasis (CRC-LM), remain poorly understood. Here, we demonstrate that CRC-EVs activate NOD1 in macrophages to initiate secretion of inflammatory cytokines and chemokines. NOD1-activated macrophages also promote CRC cell migration, while in a murine model of liver metastasis (LM), NOD1-deficient mice exhibit reduced metastasis following CRC-EV treatment. Furthermore, cell division cycle 42 (CDC42), a small Rho guanosine-5'-triphosphate (GTP)ase, is delivered by CRC-EVs into macrophages where it activates NOD1. In addition, EVs from the plasma of patients with CRC-LM mediate NOD1 activation in human peripheral blood mononuclear cells. Moreover, high NOD1 expression in tumour tissues is associated with poor prognosis of CRC-LM. Our findings suggest that CRC-EVs activate NOD1 to promote tumour metastasis, thus, NOD1 may serve as a potential target in the diagnosis and treatment of CRC-LM.

Emerging role of non-coding RNAs in glucose metabolic reprogramming and chemoresistance in colorectal cancer

Metabolic reprogramming plays a critical role in colorectal cancer (CRC). It contributes to CRC by shaping metabolic phenotypes and causing uncontrolled proliferation of CRC cells. Glucose metabolic reprogramming is common in carcinogenesis and cancer progression. Growing evidence has implicated the modifying effects of non-coding RNAs (ncRNAs) in glucose metabolic reprogramming and chemoresistance in CRC. In this review, we have summarized currently published studies investigating the role of ncRNAs in glucose metabolic alterations and chemoresistance in CRC. Elucidating the interplay between ncRNAs and glucose metabolic reprogramming provides insight into exploring novel biomarkers for the diagnosis and prognosis prediction of CRC.

MiR-26a-5p as a useful therapeutic target for upper tract urothelial carcinoma by regulating WNT5A/β-catenin signaling

The role of miRNAs in cancer and their possible function as therapeutic agents are interesting and needed further investigation. The miR-26a-5p had been demonstrated as a tumor suppressor in various cancers. However, the importance of miR-26a-5p regulation in upper tract urothelial carcinoma (UTUC) remains unclear. Here, we aimed to explore the miR-26a-5p expression in UTUC tissues and to identify its regulatory targets and signal network involved in UTUC tumorigenesis. The miR-26a-5p expression was validated by quantitative real-time polymerase chain reaction (qPCR) using renal pelvis tissue samples from 22 patients who were diagnosed with UTUC and 64 cases of renal pelvis tissue microarray using in situ hybridization staining. BFTC-909 UTUC cells were used to examine the effects of miR-26a-5p genetic delivery on proliferation, migration and expression of epithelial-to-mesenchymal transition (EMT) markers. MiR-26a-5p was significantly down-regulated in UTUC tumors compared to adjacent normal tissue and was decreased with histological grades. Moreover, restoration of miR-26a-5p showed inhibition effects on proliferation and migration of BFTC-909 cells. In addition, miR-26a-5p delivery regulated the EMT marker expression and inhibited WNT5A/β-catenin signaling and expression of downstream molecules including NF-κB and MMP-9 in BFTC-909 cells. This study demonstrated that miR-26a-5p restoration may reverse EMT process and regulate WNT5A/β-catenin signaling in UTUC cells. Further studies warranted to explore the potential roles in biomarkers for diagnostics and prognosis, as well as novel therapeutics targets for UTUC treatment.

Exosomes Regulate NLRP3 Inflammasome in Diseases

Emerging evidence has suggested the unique and critical role of exosomes as signal molecules vector in various diseases. Numerous researchers have been trying to identify how these exosomes function in immune progression, as this could promote their use as biomarkers for the disease process and potential promising diagnostic tools. NOD-like receptor (NLR) family, pyrin domain containing 3 (NLRP3), a tripartite protein, contains three functional domains a central nucleotide-binding and oligomerization domain (NACHT), an N-terminal pyrin domain (PYD), and a leucine-rich repeat domain (LRR). Of note, existing studies have identified exosome as a novel mediator of the NLRP3 inflammasome, which is critical in diseases progression. However, the actual mechanisms and clinical treatment related to exosomes and NLRP3 are still not fully understood. Herein, we presented an up-to-date review of exosomes and NLRP3 in diseases, outlining what is known about the role of exosomes in the activation of NLRP3 inflammasome and also highlighting areas of this topic that warrant further study.

5-aza-2'-deoxycytidine potentiates anti-tumor immunity in colorectal peritoneal metastasis by modulating ABC A9-mediated cholesterol accumulation in macrophages

Background: 5-aza-2'-deoxycytidine (5Aza), a DNA methyltransferase (DNMT) inhibitor, could activate tumor adaptive immunity to inhibit tumor progression. However, the molecular mechanisms by which 5Aza regulates tumor immune microenvironment are still not fully understood.

Methods: The role of 5Aza in immune microenvironment of peritoneal carcinomatosis (PC) of colorectal cancer (CRC) was investigated. The effects of 5Aza on macrophage activation were studied by flow cytometry, real-time PCR, Western blotting assays, and Drug Affinity Responsive Target Stability (DARTS). The effects of 5Aza on tumor immunity were validated in stromal macrophages and T cells from CRC patients.

Results: 5Aza could stimulate the activation of macrophages toward an M1-like phenotype and subsequent activation of T cells in premetastatic fat tissues, and ultimately suppress CRC-PC in immune-competent mouse models. Mechanistically, 5Aza stimulated primary mouse macrophages toward to a M1-like phenotype characterized by the increase of p65 phosphorylation and IL-6 expression. Furthermore, we screened and identified ATP-binding cassette transporter A9 (ABC A9) as a binding target of 5Aza. 5Aza induced cholesterol accumulation, p65 phosphorylation and IL-6 expression in an ABC A9-dependent manner. Pharmacological inhibition of NF-κB, or genetic depletion of IL-6 abolished the antitumor effect of 5Aza in mice. In addition, the antitumor effect of 5Aza was synergistically potentiated by conventional chemotherapeutic drugs 5-Fu or OXP. Finally, we validated the reprogramming role of 5Aza in antitumor immunity in stromal macrophages and T cells from CRC patients.

Conclusions: Taken together, our findings showed for the first time that 5Aza suppressed CRC-PC by regulating macrophage-dependent T cell activation in premetastatic microenvironment, meanwhile uncovered a DNA methylation-independent mechanism of 5Aza in regulating ABC A9-associated cholesterol metabolism and macrophage activation.

Macrophage-Based Combination Therapies as a New Strategy for Cancer Immunotherapy

BACKGROUND

Cells of the immune system can inhibit tumor growth and progression; however, immune cells can also promote tumor cell growth, survival, and angiogenesis as a result of the immunosuppressive microenvironments. In the last decade, a growing number of new therapeutic strategies focused on reversing the immunosuppressive status of tumor microenvironments (TMEs), to reprogram the TME to be normal, and to further activate the antitumor functions of immune cells. Most of the "hot tumors" are encompassed with M2 macrophages promoting tumor growth, and the accumulation of M2 macrophages into tumor islets leads to poor prognosis in a wide variety of tumors.

SUMMARY

Therefore, how to uncover more immunosuppressive signals and to reverse the M2 tumor-associated macrophages (TAMs) to M1-type macrophages is essential for reversing the immunosuppressive state. Except for reeducation of TAMs in the cancer immunotherapy, macrophages as central effectors and regulators of the innate immune system have the capacity of phagocytosis and immune modulation in macrophage-based cell therapies.

KEY MESSAGES

We review the current macrophage-based cell therapies that use genetic engineering to augment macrophage functionalities with antitumor activity for the application of novel genetically engineered immune cell therapeutics. A combination of TAM reeducation and macrophage-based cell strategy may bring us closer to achieving the original goals of curing cancer. In this review, we describe the characteristics, immune status, and tumor immunotherapy strategies of macrophages to provide clues and evidences for future macrophage-based immune cell therapies.

Macrophages, as a Promising Strategy to Targeted Treatment for Colorectal Cancer Metastasis in Tumor Immune Microenvironment

The tumor immune microenvironment plays a vital role in the metastasis of colorectal cancer. As one of the most important immune cells, macrophages act as phagocytes, patrol the surroundings of tissues, and remove invading pathogens and cell debris to maintain tissue homeostasis. Significantly, macrophages have a characteristic of high plasticity and can be classified into different subtypes according to the different functions, which can undergo reciprocal phenotypic switching induced by different types of molecules and signaling pathways. Macrophages regulate the development and metastatic potential of colorectal cancer by changing the tumor immune microenvironment. In tumor tissues, the tumor-associated macrophages usually play a tumor-promoting role in the tumor immune microenvironment, and they are also associated with poor prognosis. This paper reviews the mechanisms and stimulating factors of macrophages in the process of colorectal cancer metastasis and intends to indicate that targeting macrophages may be a promising strategy in colorectal cancer treatment.

α/β-Hydrolase Domain (ABHD) Inhibitors as New Potential Therapeutic Options against Lipid-Related Diseases

Much of the experimental evidence in the literature has linked altered lipid metabolism to severe diseases such as cancer, obesity, cardiovascular pathologies, diabetes, and neurodegenerative diseases. Therefore, targeting key effectors of the dysregulated lipid metabolism may represent an effective strategy to counteract these pathological conditions. In this context, α/β-hydrolase domain (ABHD) enzymes represent an important and diversified family of proteins, which are involved in the complex environment of lipid signaling, metabolism, and regulation. Moreover, some members of the ABHD family play an important role in the endocannabinoid system, being designated to terminate the signaling of the key endocannabinoid regulator 2-arachidonoylglycerol. This Perspective summarizes the research progress in the development of ABHD inhibitors and modulators: design strategies, structure-activity relationships, action mechanisms, and biological studies of the main ABHD ligands will be highlighted.

Advances in the study of cancer metastasis and calcium signaling as potential therapeutic targets

Metastasis is still the primary cause of cancer-related mortality. However, the underlying mechanisms of cancer metastasis are not yet fully understood. Currently, the epithelial-mesenchymal transition, metabolic remodeling, cancer cell intercommunication and the tumor microenvironment including diverse stromal cells, are reported to affect the metastatic process of cancer cells. Calcium ions (Ca²⁺) are ubiquitous second messengers that manipulate cancer metastasis by affecting signaling pathways. Diverse transporter/pump/channel-mediated Ca²⁺ currents form Ca²⁺ oscillations that can be decoded by Ca²⁺-binding proteins, which are promising prognostic biomarkers and therapeutic targets of cancer metastasis. This paper presents a review of the advances in research on the mechanisms underlying cancer metastasis and the roles of Ca²⁺-related signals in these events.

Stresses in the metastatic cascade: molecular mechanisms and therapeutic opportunities

In this review, Shen and Kang provide an overview of the tumor-intrinsic and microenvironment- and treatment-induced stresses that tumor cells encounter in the metastatic cascade and the molecular pathways they develop to relieve these stresses.

Metastasis is the ultimate “survival of the fittest” test for cancer cells, as only a small fraction of disseminated tumor cells can overcome the numerous hurdles they encounter during the transition from the site of origin to a distinctly different distant organ in the face of immune and therapeutic attacks and various other stresses. During cancer progression, tumor cells develop a variety of mechanisms to cope with the stresses they encounter, and acquire the ability to form metastases. Restraining these stress-releasing pathways could serve as potentially effective strategies to prevent or reduce metastasis and improve the survival of cancer patients. Here, we provide an overview of the tumor-intrinsic, microenvironment- and treatment-induced stresses that tumor cells encounter in the metastatic cascade and the molecular pathways they develop to relieve these stresses. We also summarize the preclinical and clinical studies that evaluate the potential therapeutic benefit of targeting these stress-relieving pathways.

Inflammation-Induced Tumorigenesis and Metastasis

Inflammation, especially chronic inflammation, plays a pivotal role in tumorigenesis and metastasis through various mechanisms and is now recognized as a hallmark of cancer and an attractive therapeutic target in cancer. In this review, we discuss recent advances in molecular mechanisms of how inflammation promotes tumorigenesis and metastasis and suppresses anti-tumor immunity in various types of solid tumors, including esophageal, gastric, colorectal, liver, and pancreatic cancer as well as hematopoietic malignancies.

Plasma cells shape the mesenchymal identity of ovarian cancers through transfer of exosome-derived microRNAs

Ovarian cancer represents a highly lethal disease that poses a substantial burden for females, with four main molecular subtypes carrying distinct clinical outcomes. Here, we demonstrated that plasma cells, a subset of antibody-producing B cells, were enriched in the mesenchymal subtype of high-grade serous ovarian cancers (HGSCs). Plasma cell abundance correlated with the density of mesenchymal cells in clinical specimens of HGSCs. Coculture of nonmesenchymal ovarian cancer cells and plasma cells induced a mesenchymal phenotype of tumor cells in vitro and in vivo. Phenotypic switch was mediated by the transfer of plasma cell–derived exosomes containing miR-330-3p into nonmesenchymal ovarian cancer cells. Exosome-derived miR-330-3p increased expression of junctional adhesion molecule B in a noncanonical fashion. Depletion of plasma cells by bortezomib reversed the mesenchymal characteristics of ovarian cancer and inhibited in vivo tumor growth. Collectively, our work suggests targeting plasma cells may be a novel approach for ovarian cancer therapy.

Metabolic regulatory crosstalk between tumor microenvironment and tumor-associated macrophages

Macrophages phagocytize pathogens to initiate innate immunity and products from the tumor microenvironment (TME) to mediate tumor immunity. The loss of tumor-associated macrophage (TAM)-mediated immune responses results in immune suppression. To reverse this immune disorder, the regulatory mechanism of TAMs in the TME needs to be clarified. Immune molecules (cytokines and chemokines) from TAMs and the TME have been widely accepted as mutual mediators of signal transduction in the past few decades. Recently, researchers have tried to seek the intrinsic mechanism of TAM phenotypic and functional changes through metabolic connections. Numerous metabolites derived from the TME have been identified that induce the cell-cell crosstalk with TAMs. The bulk tumor cells, immune cells, and stromal cells produce metabolites in the TME that are involved in the metabolic regulation of TAMs. Meanwhile, some products from TAMs regulate the biological functions of the tumor as well. Here, we review the recent reports demonstrating the metabolic regulation between TME and TAMs.

Dietary fats suppress the peritoneal seeding of colorectal cancer cells through the TLR4/Cxcl10 axis in adipose tissue macrophages

Peritoneal carcinomatosis (PC) of colorectal cancer (CRC) is a terminal phase of malignancy with no effective strategies for the prevention of this condition. Here we established PC models in mice by intraperitoneal engraftment of CRC cells and revealed an unexpected role for a high-fat diet (HFD) in preventing metastatic seeding in the visceral fat. Mechanistically, the HFD stimulated the activation of adipose tissue macrophages (ATMs) toward an M1-like phenotype and enhanced ATM tumor phagocytosis in a TLR4-dependent manner. Furthermore, the TLR4–Cxcl10 axis in ATMs promoted T cell recruitment, and M1-like macrophages stimulated T cell activation in tumor-seeded fats. The inhibitory effect of the HFD on tumor seeding was abolished with the ablation of macrophages, inactivation of T cells, or blockade of the TLR4–Cxcl10 axis in macrophages. Finally, we showed that a HFD and conventional chemotherapeutic agents (oxaliplatin or 5-fluorouracil) synergistically improved the survival of tumor-seeded mice. Collectively, our findings demonstrate that peritoneal seeding of CRC can be suppressed by short-term treatment with a HFD in the early phase, providing a novel concept for the management of these patients in the clinic.

Cancer-derived exosomal TRIM59 regulates macrophage NLRP3 inflammasome activation to promote lung cancer progression

Background

Exosomes are emerging as important mediators of the cross-talk between tumor cells and the microenvironment. The communication between tumor-derived exosomes and macrophages has a critical role in facilitating tumor progression. However, the mechanisms by which exosomes modulate tumor development in lung cancer are not fully understood.

Methods

Short hairpin RNA mediated knockdown or exogenous expression of TRIM59 combined with in vitro and in vivo assays were performed to prove the functional significance of TRIM59. Western blotting, real-time PCR, co-immunoprecipitation, immunofluorescence (IF) staining assays, proximity ligation assay (PLA), ubiquitination assays, lactate secretion and lipid droplets content measurement, and rescue experiments were used to evaluate the mechanism. Lewis lung carcinoma (LLC) cells were injected via subcutaneously or tail vein into C57BL/6 wild-type (WT) and transgenic mice to assess the role of TRIM59 in vivo.

Results

We demonstrated that tripartite motif-containing 59 (TRIM59) was expressed in lung cancer cells-derived exosomes, and can be transferred to macrophages through the exosomes. Activated macrophages by TRIM59 promote lung cancer progression in vitro and in vivo. Mechanistic investigations revealed that TRIM59 physically interacts with abhydrolase domain containing 5 (ABHD5) and directly induced the ubiquitination of ABHD5 and led to its proteasome-dependent degradation. ABHD5, an lipolytic co-activator, deficiency induced metabolic reprogramming and enabled NLRP3 inflammasome activation in macrophages. Further studies showed that the exacerbation of NLRP3 inflammasome activation by ABHD5 deficiency, provides a positive feedback loop to promote cancer progression by preferentially secrete the proinflammatory cytokine IL-1β.

Conclusions

Collectively, these data indicate that tumor-derived exosomal TRIM59 converts macrophages to tumor-promoting functions of macrophages via regulating ABHD5 proteasomal degradation, to activate NLRP3 inflammasome signaling pathway to promote lung cancer progression by IL-1β secretion. Our findings also indicate that tumor-derived exosomal TRIM59 has an important role in intercellular communication for fostering an inflammatory microenvironment and promoting lung metastasis.

Emerging role of metabolic reprogramming in tumor immune evasion and immunotherapy

Mounting evidence has revealed that the therapeutic efficacy of immunotherapies is restricted to a small portion of cancer patients. A deeper understanding of how metabolic reprogramming in the tumor microenvironment (TME) regulates immunity remains a major challenge to tumor eradication. It has been suggested that metabolic reprogramming in the TME may affect metabolism in immune cells and subsequently suppress immune function. Tumor cells compete with infiltrating immune cells for nutrients and metabolites. Notably, the immunosuppressive TME is characterized by catabolic and anabolic processes that are critical for immune cell function, and elevated inhibitory signals may favor cancer immune evasion. The major energy sources that supply different immune cell subtypes also undergo reprogramming. We herein summarize the metabolic remodeling in tumor cells and different immune cell subtypes and the latest advances underlying the use of metabolic checkpoints in antitumor immunotherapies. In this context, targeting both tumor and immune cell metabolic reprogramming may enhance therapeutic efficacy.

Dysregulation of metabolic enzymes in tumor and stromal cells: Role in oncogenesis and therapeutic opportunities

Altered cellular metabolism is a hallmark of cancer. Metabolic rewiring in cancer cells occurs due to the activation of oncogenes, inactivation of tumor suppressor genes, and/or other adaptive changes in cell signaling pathways. Furthermore, altered metabolism is also reported in tumor-corrupted stromal cells as a result of their interaction with cancer cells or due to their adaptation in the dynamic tumor microenvironment. Metabolic alterations are associated with dysregulation of metabolic enzymes and tumor-stromal metabolic crosstalk is vital for the progressive malignant journey of the tumor cells. Therefore, several therapies targeting metabolic enzymes have been evaluated and/or are being investigated in preclinical and clinical studies. In this review, we discuss some important metabolic enzymes that are altered in tumor and/or stromal cells, and focus on their role in supporting tumor growth. Moreover, we also discuss studies carried out in various cancers to target these metabolic abnormalities for therapeutic exploitation.

The Agpat4/LPA axis in colorectal cancer cells regulates antitumor responses via p38/p65 signaling in macrophages

Lipid metabolic reprogramming plays an essential role in regulating the progression of colorectal cancer (CRC). However, the effect of lysophosphatidic acid (LPA) metabolism on CRC development is incompletely characterized. Here, we compared the mRNA levels of human CRC tissues to those of paracarcinoma tissues and focused on the notably enriched LPA metabolic pathways. We identified and verified that 1-acylglycerol-3-phosphate O-acyltransferase 4 (Agpat4) was aberrantly expressed in CRC tissues and predicted poor survival in CRC patients. Manipulating Agpat4 expression in CRC cells did not affect the growth or migration of CRC cells in vitro, whereas Agpat4 silencing suppressed CRC cell growth in subcutaneous and peritoneal xenograft models. Mechanistically, Agpat4 silencing-induced LPA release from CRC cells and polarized macrophages to an M1-like phenotype through LPA receptors 1 and 3. This M1 activation, characterized by elevated p38/p65 signaling and increased proinflammatory cytokines, promoted the infiltration and activation of CD4⁺ and CD8⁺ T cells in the tumor microenvironment. Modulation of the Agpat4/LPA/p38/p65 axis regulated macrophage polarization, T-cell activity and CRC progression. Notably, combined therapy with LPA and regular chemotherapy drugs synergistically suppressed CRC development. Taken together, our results showed that the Agpat4/LPA axis in CRC cells regulated p38/p65 signaling-dependent macrophage polarization, T-cell activation, and CRC progression. The Agpat4/LPA/p38/p65 axis might represent a potential target for therapy in the clinic.

CGI-58: Versatile Regulator of Intracellular Lipid Droplet Homeostasis

Comparative gene identification-58 (CGI-58), also known as α/β-hydrolase domain-containing 5 (ABHD5), is a member of a large family of proteins containing an α/β-hydrolase-fold. CGI-58 is well-known as the co-activator of adipose triglyceride lipase (ATGL), which is a key enzyme initiating cytosolic lipid droplet lipolysis. Mutations in either the human CGI-58 or ATGL gene cause an autosomal recessive neutral lipid storage disease, characterized by the excessive accumulation of triglyceride (TAG)-rich lipid droplets in the cytoplasm of almost all cell types. CGI-58, however, has ATGL-independent functions. Distinct phenotypes associated with CGI-58 deficiency commonly include ichthyosis (scaly dry skin), nonalcoholic steatohepatitis, and hepatic fibrosis. Through regulated interactions with multiple protein families, CGI-58 controls many metabolic and signaling pathways, such as lipid and glucose metabolism, energy balance, insulin signaling, inflammatory responses, and thermogenesis. Recent studies have shown that CGI-58 regulates the pathogenesis of common metabolic diseases in a tissue-specific manner. Future studies are needed to molecularly define ATGL-independent functions of CGI-58, including the newly identified serine protease activity of CGI-58. Elucidation of these versatile functions of CGI-58 may uncover fundamental cellular processes governing lipid and energy homeostasis, which may help develop novel approaches that counter against obesity and its associated metabolic sequelae.