Macropinocytosis in Cancer-Associated Fibroblasts Is Dependent on CaMKK2/ARHGEF2 Signaling and Functions to Support Tumor and Stromal Cell Fitness

High antigen-presenting CAF levels correlate with reduced glycosaminoglycan biosynthesis-heparan sulfate/heparin metabolism in immune cells and poor prognosis in esophageal squamous cell carcinoma: Insights from bulk and single-cell transcriptome profiling

In esophageal squamous cell carcinoma (ESCC), the tumor microenvironment (TME) is characterized by a significant accumulation of cancer-associated fibroblasts (CAFs), which play a pivotal role in the host response against tumor cells. While fibroblasts are known to be crucial in the metabolic reprogramming of the TME, the specific metabolic alterations induced by these cells remain largely undefined. Utilizing single-cell RNA sequencing, we have identified a distinct subpopulation of antigen-presenting CAF (apCAF) within ESCC tumors. Our findings reveal that apCAF contribute to adverse patient outcomes by remodeling the tumor metabolic environment. Notably, apCAF modulate the glycosaminoglycan biosynthesis-heparan sulfate/heparin metabolism pathway in T cells, B cells, and macrophages. Disruption of this pathway may facilitate immune evasion by the tumor. These insights underscore the critical role of CAFs in shaping the metabolic landscape of the TME and lay the groundwork for developing therapeutic strategies aimed at enhancing anti-tumor immunity.

Conserved spatial subtypes and cellular neighborhoods of cancer-associated fibroblasts revealed by single-cell spatial multi-omics

Cancer-associated fibroblasts (CAFs) are a multifaceted cell population essential for shaping the tumor microenvironment (TME) and influencing therapy responses. Characterizing the spatial organization and interactions of CAFs within complex tissue environments provides critical insights into tumor biology and immunobiology. In this study, through integrative analyses of over 14 million cells from 10 cancer types across 7 spatial transcriptomics and proteomics platforms, we discover, validate, and characterize four distinct spatial CAF subtypes. These subtypes are conserved across cancer types and independent of spatial omics platforms. Notably, they exhibit distinct spatial organizational patterns, neighboring cell compositions, interaction networks, and transcriptomic profiles. Their abundance and composition vary across tissues, shaping TME characteristics, such as levels, distribution, and state composition of tumor-infiltrating immune cells, tumor immune phenotypes, and patient survival. This study enriches our understanding of CAF spatial heterogeneity in cancer and paves the way for novel approaches to target and modulate CAFs.

Antigen-presenting fibroblasts: emerging players in immune modulation and therapeutic targets

Antigen-presenting fibroblasts are a newly recognized subset that challenges the traditional view of these cells as mere structural components. Under pathological or environmental stimuli, fibroblasts acquire antigen-presenting capabilities through the expression of MHC-II molecules and co-stimulatory factors, enabling them to interact with T cells and modulate immune responses. These specialized fibroblasts have been identified across various tissues and diseases, where they play context-dependent roles, either amplifying immune dysregulation or contributing to immune homeostasis. This review synthesizes recent advances in understanding the origins, activation, and functions of antigen-presenting fibroblasts. It highlights their role in promoting pathogenic immune responses and offering therapeutic opportunities through targeted modulation. Advancing our understanding of antigen-presenting fibroblasts holds great promise for developing innovative approaches to immune modulation and therapy across a range of diseases.

Hyperlipidemia drives tumor growth in a mouse model of obesity-accelerated breast cancer growth

Obesity is an established risk factor for breast cancer (BC), yet the specific mechanisms driving this association remain unclear. Dysregulated lipid metabolism has emerged as a key factor in cancer cell biology. While obesity is often accompanied by hyperlipidemia, the isolated impact of elevated lipid levels on BC growth has not been experimentally tested. Using the E0771 orthotopic model of obesity-accelerated BC growth in immune-competent mice, we investigated the direct role of systemic lipids in tumor growth. Combining dietary and genetic mouse models, we show that elevated circulating lipids are sufficient to accelerate BC tumor growth even in the absence of obesity or alterations in blood glucose and/or insulin levels. Pharmacological lowering of systemic lipid levels attenuates BC growth in obese mice, suggesting a direct role for lipids in fueling tumor expansion. Notably, we also show that weight loss alone, without a corresponding reduction in lipid levels such as that induced by a ketogenic diet, fails to protect against BC, highlighting the necessity of targeting lipid metabolism in obesity-associated BC. Our findings establish hyperlipidemia as a critical driver of BC progression and suggest that lipid-lowering interventions may be a promising strategy to mitigate BC risk in obese individuals.

Alcohol-induced C/EBP β-driven VIRMA decreases oxidative stress and promotes pancreatic ductal adenocarcinoma growth and metastasis via the m6A/YTHDF2/SLC43A2 pathway

N6-methyladenosine (m6A) plays a role in the development of tumors. However, the specific role of VIRMA, an RNA methyltransferase, in pancreatic ductal adenocarcinoma (PDAC) remains unclear. This study shows that VIRMA expression is elevated in PDAC. Increased VIRMA levels promoted PDAC growth and spread, while reducing VIRMA expression slowed these processes. VIRMA facilitated SLC43A2 mRNA degradation through an m6A-YTHDF2 pathway. The resulting decrease in SLC43A2 reduced phenylalanine absorption and oxidative stress, further driving PDAC progression. Furthermore, alcohol increased C/EBP β expression, which bound to VIRMA's promoter, enhancing its transcription. These findings suggest a connection between alcohol consumption, m6A modifications, and phenylalanine absorption in PDAC progression, offering a new approach to combat this disease.

Targeting glutamine metabolism crosstalk with tumor immune response

Glutamine, akin to glucose, is a fundamental nutrient for human physiology. Tumor progression is often accompanied by elevated glutamine consumption, resulting in a disrupted nutritional balance and metabolic reprogramming within the tumor microenvironment. Furthermore, immune cells, which depend on glutamine for metabolic support, may experience functional impairments and dysregulation. Although the role of glutamine in tumors has been extensively studied, the specific impact of glutamine competition on immune responses, as well as the precise cellular alterations within immune cells, remains incompletely understood. In this review, we summarize the consequences of glutamine deprivation induced by tumor-driven glutamine uptake on immune cells, assessing the underlying mechanisms from the perspective of various components of the immune microenvironment. Additionally, we discuss the potential synergistic effects of glutamine supplementation and immunotherapy, offering insights into future research directions. This review provides compelling evidence for the integration of glutamine metabolism and immunotherapy as a promising strategy in cancer therapy.

Class III Phosphatidylinositol-3 Kinase/Vacuolar Protein Sorting 34 in Cardiovascular Health and Disease

Phosphatidylinositol-3 kinases (PI3Ks) play a critical role in maintaining cardiovascular health and the development of cardiovascular diseases (CVDs). Specifically, vacuolar Protein Sorting 34 (VPS34) or PIK3C3, the only member of Class III PI3K, plays an important role in CVD progression. The main function of VPS34 is inducing the production of phosphatidylinositol 3-phosphate, which, together with other essential structural and regulatory proteins in forming VPS34 complexes, further regulates the mammalian target of rapamycin activation, autophagy, and endocytosis. VPS34 is found to have crucial functions in the cardiovascular system, including dictating the proliferation and survival of vascular smooth muscle cells and cardiomyocytes and the formation of thrombosis. This review aims to summarize our current knowledge and recent advances in understanding the function and regulation of VPS34 in cardiovascular health and disease. We also discuss the current development of VPS34 inhibitors and their potential to treat CVDs.

Genetics and biology of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) poses a grim prognosis for patients. Recent multidisciplinary research efforts have provided critical insights into its genetics and tumor biology, creating the foundation for rational development of targeted and immune therapies. Here, we review the PDAC genomic landscape and the role of specific oncogenic events in tumor initiation and progression, as well as their contributions to shaping its tumor biology. We further summarize and synthesize breakthroughs in single-cell and metabolic profiling technologies that have illuminated the complex cellular composition and heterotypic interactions of the PDAC tumor microenvironment, with an emphasis on metabolic cross-talk across cancer and stromal cells that sustains anabolic growth and suppresses tumor immunity. These conceptual advances have generated novel immunotherapy regimens, particularly cancer vaccines, which are now in clinical testing. We also highlight the advent of KRAS targeted therapy, a milestone advance that has transformed treatment paradigms and offers a platform for combined immunotherapy and targeted strategies. This review provides a perspective summarizing current scientific and therapeutic challenges as well as practice-changing opportunities for the PDAC field at this major inflection point.

CARMIL1-AA selectively inhibits macropinocytosis while sparing autophagy

Macropinocytosis is reported to fuel tumor growth and drug resistance by allowing cancer cells to scavenge extracellular macromolecules. However, accurately defining the role of macropinocytosis in cancer depends on our ability to selectively block this process. 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) is widely used to inhibit macropinocytosis but affects multiple Na+/H+ exchangers (NHE) that regulate cytoplasmic and organellar pH. Consistent with this, we report that EIPA slows proliferation to a greater extent than can be accounted for by macropinocytosis inhibition and triggers conjugation of ATG8 to single membranes (CASM). Knocking down only NHE1 would not avoid macropinocytosis-independent effects on pH. Moreover, contrary to published reports, NHE1 loss did not block macropinocytosis in multiple cell lines. Knocking down CARMIL1 with CRISPR-Cas9 editing limited macropinocytosis, but only by 50%. In contrast, expressing the CARMIL1-AA mutant inhibits macropinocytosis induced by a wide range of macropinocytic stimuli to a similar extent as EIPA. CARMIL1-AA expression did not inhibit proliferation, highlighting the shortcomings of EIPA as a macropinocytosis inhibitor. Importantly, autophagy, another actin dependent, nutrient-producing process, was not affected by CARMIL1-AA expression. In sum, constitutive or inducible CARMIL1-AA expression reduced macropinocytosis without affecting proliferation, RAC activation, or autophagy, other processes that drive tumor initiation and progression.

Plasticity and Tumor Microenvironment in Pancreatic Cancer: Genetic, Metabolic, and Immune Perspectives

Cancer has long been believed to be a genetic disease caused by the accumulation of mutations in key genes involved in cellular processes. However, recent advances in sequencing technology have demonstrated that cells with cancer driver mutations are also present in normal tissues in response to aging, environmental damage, and chronic inflammation, suggesting that not only intrinsic factors within cancer cells, but also environmental alterations are important key factors in cancer development and progression. Pancreatic cancer tissue is mostly comprised of stromal cells and immune cells. The desmoplasmic microenvironment characteristic of pancreatic cancer is hypoxic and hypotrophic. Pancreatic cancer cells may adapt to this environment by rewiring their metabolism through epigenomic changes, enhancing intrinsic plasticity, creating an acidic and immunosuppressive tumor microenvironment, and inducing noncancerous cells to become tumor-promoting. In addition, pancreatic cancer has often metastasized to local and distant sites by the time of diagnosis, suggesting that a similar mechanism is operating from the precancerous stage. Here, we review key recent findings on how pancreatic cancers acquire plasticity, undergo metabolic reprogramming, and promote immunosuppressive microenvironment formation during their evolution. Furthermore, we present the following two signaling pathways that we have identified: one based on the small G-protein ARF6 driven by KRAS/TP53 mutations, and the other based on the RNA-binding protein Arid5a mediated by inflammatory cytokines, which promote both metabolic reprogramming and immune evasion in pancreatic cancer. Finally, the striking diversity among pancreatic cancers in the relative importance of mutational burden and the tumor microenvironment, their clinical relevance, and the potential for novel therapeutic strategies will be discussed.

Macropinocytosis controls metabolic stress-driven CAF subtype identity in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) tumors are deficient in glutamine, an amino acid that tumor cells and CAFs use to sustain their fitness. In PDAC, both cell types stimulate macropinocytosis as an adaptive response to glutamine depletion. CAFs play a critical role in sculpting the tumor microenvironment, yet how adaptations to metabolic stress impact the stromal architecture remains elusive. In this study, we find that macropinocytosis functions to control CAF subtype identity when glutamine is limiting. Our data demonstrate that metabolic stress leads to an intrinsic inflammatory CAF (iCAF) program driven by MEK/ERK signaling. Utilizing in vivo models, we find that blocking macropinocytosis alters CAF subtypes and reorganizes the tumor stroma. Importantly, these changes in stromal architecture can be exploited to sensitize PDAC to immunotherapy and chemotherapy. Our findings demonstrate that metabolic stress plays a role in shaping the tumor microenvironment, and that this attribute can be harnessed for therapeutic impact.

Cell polarity proteins promote macropinocytosis in response to metabolic stress

Macropinocytosis has emerged as a scavenging pathway that cancer cells exploit to survive in a nutrient-deprived microenvironment. Tumor cells are especially reliant on glutamine for their survival, and in pancreatic ductal adenocarcinoma (PDAC) cells, glutamine deficiency can enhance the stimulation of macropinocytosis. Here, we identify the atypical protein kinase C (aPKC) enzymes, PKCζ and PKCι, as regulators of macropinocytosis. In normal epithelial cells, aPKCs associate with the scaffold proteins Par3 and Par6 to regulate cell polarity, affecting several targets, including the Par1 kinases and we find that each of these proteins is required for macropinocytosis. Mechanistically, aPKCs are regulated by EGFR signaling or by the transcription factor CREM to promote the Par3 relocation to microtubules, facilitating macropinocytosis in a dynein-dependent manner. Importantly, cell fitness impairment caused by aPKC depletion is rescued by the restoration of macropinocytosis and aPKCs support PDAC growth in vivo. Our findings enhance our understanding of the mechanistic underpinnings that control macropinocytic uptake in the context of metabolic stress.

Cancer associated fibroblasts and metabolic reprogramming: unraveling the intricate crosstalk in tumor evolution

Metabolic reprogramming provides tumors with an energy source and biofuel to support their survival in the malignant microenvironment. Extensive research into the intrinsic oncogenic mechanisms of the tumor microenvironment (TME) has established that cancer-associated fibroblast (CAFs) and metabolic reprogramming regulates tumor progression through numerous biological activities, including tumor immunosuppression, chronic inflammation, and ecological niche remodeling. Specifically, immunosuppressive TME formation is promoted and mediators released via CAFs and multiple immune cells that collectively support chronic inflammation, thereby inducing pre-metastatic ecological niche formation, and ultimately driving a vicious cycle of tumor proliferation and metastasis. This review comprehensively explores the process of CAFs and metabolic regulation of the dynamic evolution of tumor-adapted TME, with particular focus on the mechanisms by which CAFs promote the formation of an immunosuppressive microenvironment and support metastasis. Existing findings confirm that multiple components of the TME act cooperatively to accelerate the progression of tumor events. The potential applications and challenges of targeted therapies based on CAFs in the clinical setting are further discussed in the context of advancing research related to CAFs.

Kinome state is predictive of cell viability in pancreatic cancer tumor and cancer-associated fibroblast cell lines

Numerous aspects of cellular signaling are regulated by the kinome-the network of over 500 protein kinases that guides and modulates information transfer throughout the cell. The key role played by both individual kinases and assemblies of kinases organized into functional subnetworks leads to kinome dysregulation driving many diseases, particularly cancer. In the case of pancreatic ductal adenocarcinoma (PDAC), a variety of kinases and associated signaling pathways have been identified for their key role in the establishment of disease as well as its progression. However, the identification of additional relevant therapeutic targets has been slow and is further confounded by interactions between the tumor and the surrounding tumor microenvironment. In this work, we attempt to link the state of the human kinome, or kinotype, with cell viability in treated, patient-derived PDAC tumor and cancer-associated fibroblast cell lines. We applied classification models to independent kinome perturbation and kinase inhibitor cell screen data, and found that the inferred kinotype of a cell has a significant and predictive relationship with cell viability. We further find that models are able to identify a set of kinases whose behavior in response to perturbation drive the majority of viability responses in these cell lines, including the understudied kinases CSNK2A1/3, CAMKK2, and PIP4K2C. We next utilized these models to predict the response of new, clinical kinase inhibitors that were not present in the initial dataset for model devlopment and conducted a validation screen that confirmed the accuracy of the models. These results suggest that characterizing the perturbed state of the human protein kinome provides significant opportunity for better understanding of signaling behavior and downstream cell phenotypes, as well as providing insight into the broader design of potential therapeutic strategies for PDAC.

Novel selective inhibitors of macropinocytosis-dependent growth in pancreatic ductal carcinoma

Macropinocytosis is a cellular process that enables cells to engulf extracellular material, such as nutrients, growth factors, and even whole cells. It is involved in several physiological functions as well as pathological conditions. In cancer cells, macropinocytosis plays a crucial role in promoting tumor growth and survival under nutrient-limited conditions. In particular KRAS mutations have been identified as main drivers of macropinocytosis in pancreatic, breast, and non-small cell lung cancers. We performed a high-content screening to identify inhibitors of macropinocytosis in pancreatic ductal adenocarcinoma (PDAC)-derived cells, aiming to prevent nutrient scavenging of PDAC tumors. The screening campaign was conducted in a well-known pancreatic KRAS-mutated cell line (MIAPaCa-2) cultured under nutrient deprivation and using FITC-dextran to precisely quantify macropinocytosis. We assembled a collection of 3584 small molecules, including drugs approved by the Food and Drug Administration (FDA), drug-like molecules against molecular targets, kinase-targeted compounds, and molecules designed to hamper protein-protein interactions. We identified 28 molecules that inhibited macropinocytosis, with potency ranging from 0.4 to 29.9 μM (EC50). A few of them interfered with other endocytic pathways, while 11 compounds did not and were therefore considered specific "bona fide" macropinocytosis inhibitors and further characterized. Four compounds (Ivermectin, Tyrphostin A9, LY2090314, and Pyrvinium Pamoate) selectively hampered nutrient scavenging in KRAS-mutated cancer cells. Their ability to impair albumin-dependent proliferation was replicated both in different 2D cell culture systems and 3D organotypic models. These findings provide a new set of compounds specifically targeting macropinocytosis, which could have therapeutic applications in cancer and infectious diseases.

Ferroptosis: principles and significance in health and disease

Ferroptosis, an iron-dependent form of cell death characterized by uncontrolled lipid peroxidation, is governed by molecular networks involving diverse molecules and organelles. Since its recognition as a non-apoptotic cell death pathway in 2012, ferroptosis has emerged as a crucial mechanism in numerous physiological and pathological contexts, leading to significant therapeutic advancements across a wide range of diseases. This review summarizes the fundamental molecular mechanisms and regulatory pathways underlying ferroptosis, including both GPX4-dependent and -independent antioxidant mechanisms. Additionally, we examine the involvement of ferroptosis in various pathological conditions, including cancer, neurodegenerative diseases, sepsis, ischemia-reperfusion injury, autoimmune disorders, and metabolic disorders. Specifically, we explore the role of ferroptosis in response to chemotherapy, radiotherapy, immunotherapy, nanotherapy, and targeted therapy. Furthermore, we discuss pharmacological strategies for modulating ferroptosis and potential biomarkers for monitoring this process. Lastly, we elucidate the interplay between ferroptosis and other forms of regulated cell death. Such insights hold promise for advancing our understanding of ferroptosis in the context of human health and disease.

Current and future immunotherapeutic approaches in pancreatic cancer treatment

Pancreatic cancer is a major cause of cancer-related death, but despondently, the outlook and prognosis for this resistant type of tumor have remained grim for a long time. Currently, it is extremely challenging to prevent or detect it early enough for effective treatment because patients rarely exhibit symptoms and there are no reliable indicators for detection. Most patients have advanced or spreading cancer that is difficult to treat, and treatments like chemotherapy and radiotherapy can only slightly prolong their life by a few months. Immunotherapy has revolutionized the treatment of pancreatic cancer, yet its effectiveness is limited by the tumor's immunosuppressive and hard-to-reach microenvironment. First, this article explains the immunosuppressive microenvironment of pancreatic cancer and highlights a wide range of immunotherapy options, including therapies involving oncolytic viruses, modified T cells (T-cell receptor [TCR]-engineered and chimeric antigen receptor [CAR] T-cell therapy), CAR natural killer cell therapy, cytokine-induced killer cells, immune checkpoint inhibitors, immunomodulators, cancer vaccines, and strategies targeting myeloid cells in the context of contemporary knowledge and future trends. Lastly, it discusses the main challenges ahead of pancreatic cancer immunotherapy.

CAFs-Associated Genes (CAFGs) in Pancreatic Ductal Adenocarcinoma (PDAC) and Novel Therapeutic Strategy

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive cancer with striking fibrosis, and its mortality rate is ranked second across human cancers. Cancer-associated fibroblasts (CAFs) play a critical role in PDAC progression, and we reviewed the molecular understanding of PDAC CAFs and novel therapeutic potential at present. CAFs-associated genes (CAFGs) were tentatively classified into three categories by stroma specificity representing stroma/epithelia expression ratios (SE ratios). The recent classification using single cell transcriptome technology clarified that CAFs were composed of myofibroblasts (myCAFs), inflammatory CAFs (iCAFs), and other minor ones (e.g., POSTN-CAFs and antigen presenting CAFs, apCAFs). LRRC15 is a myCAFs marker, and myCAFs depletion by diphtheria toxin induces the rapid accumulation of cytotoxic T lymphocytes (CTLs) and therefore augment PDL1 antibody treatments. This finding proposes that myCAFs may be a critical regulator of tumor immunity in terms of PDAC progression. myCAFs are located in CAFs adjacent to tumor cells, while iCAFs marked by PDPN and/or COL14A1 are distant from tumor cells, where hypoxic and acidic environments being located in iCAFs putatively due to poor blood supply is consistent with HIF1A and GPR68 expressions. iCAFs may be shared with SASP (secretion-associated phenotypes) in senescent CAFs. myCAFs are classically characterized by CAFGs induced by TGFB1, while chemoresistant CAFs with SASP may dependent on IL6 expression and accompanied by STAT3 activation. Recently, it was found that the unique metabolism of CAFs can be targeted to prevent PDAC progression, where PDAC cells utilize glucose, whereas CAFs in turn utilize lactate, which may be epigenetically regulated, mediated by its target genes including CXCR4. In summary, CAFs have unique molecular characteristics, which have been rigorously clarified as novel therapeutic targets of PDAC progression.

PRL1 and PRL3 promote macropinocytosis via its lipid phosphatase activity

PRL1 and PRL3, members of the protein tyrosine phosphatase family, have been associated with cancer metastasis and poor prognosis. Despite extensive research on their protein phosphatase activity, their potential role as lipid phosphatases remains elusive. Methods: We conducted comprehensive investigations to elucidate the lipid phosphatase activity of PRL1 and PRL3 using a combination of cellular assays, biochemical analyses, and protein interactome profiling. Functional studies were performed to delineate the impact of PRL1/3 on macropinocytosis and its implications in cancer biology. Results: Our study has identified PRL1 and PRL3 as lipid phosphatases that interact with phosphoinositide (PIP) lipids, converting PI(3,4)P2 and PI(3,5)P2 into PI(3)P on the cellular membranes. These enzymatic activities of PRLs promote the formation of membrane ruffles, membrane blebbing and subsequent macropinocytosis, facilitating nutrient extraction, cell migration, and invasion, thereby contributing to tumor development. These enzymatic activities of PRLs promote the formation of membrane ruffles, membrane blebbing and subsequent macropinocytosis. Additionally, we found a correlation between PRL1/3 expression and glioma development, suggesting their involvement in glioma progression. Conclusions: Combining with the knowledge that PRLs have been identified to be involved in mTOR, EGFR and autophagy, here we concluded the physiological role of PRL1/3 in orchestrating the nutrient sensing, absorbing and recycling via regulating macropinocytosis through its lipid phosphatase activity. This mechanism could be exploited by tumor cells facing a nutrient-depleted microenvironment, highlighting the potential therapeutic significance of targeting PRL1/3-mediated macropinocytosis in cancer treatment.

The Role of Stroma in Cancer Metabolism

The altered metabolism of tumor cells is a well-known hallmark of cancer and is driven by multiple factors such as mutations in oncogenes and tumor suppressor genes, the origin of the tissue where the tumor arises, and the microenvironment of the tumor. These metabolic changes support the growth of cancer cells by providing energy and the necessary building blocks to sustain proliferation. Targeting these metabolic alterations therapeutically is a potential strategy to treat cancer, but it is challenging due to the metabolic plasticity of tumors. Cancer cells have developed ways to scavenge nutrients through autophagy and macropinocytosis and can also form metabolic networks with stromal cells in the tumor microenvironment. Understanding the role of the tumor microenvironment in tumor metabolism is crucial for effective therapeutic targeting. This review will discuss tumor metabolism and the contribution of the stroma in supporting tumor growth through metabolic interactions.

Biodistribution and therapeutic efficacy of a gold nanoparticle-based targeted drug delivery system against pancreatic cancer

Pancreatic cancer is characterized by desmoplasia; crosstalk between pancreatic cancer cells (PCCs) and pancreatic stellate cells (PSCs) leads to the deposition of extracellular matrix proteins in the tumor environment resulting in poor vascularity. Targeting either PCCs or PSCs individually has produced mixed results, and there is currently no effective strategy to target both cell types simultaneously. Previously, we demonstrated, through in vitro cell culture experiments, that a specific gold nanoparticle-based nanoformulation containing the anti-EGFR antibody cetuximab (C225) as a targeting agent and gemcitabine as a chemotherapeutic agent effectively targets both PCCs and PSCs simultaneously. Herein, we extend our studies to test the ability of these in vitro tested nano formulations to inhibit tumor growth in an orthotopic co-implantation model of pancreatic cancer in vivo. Orthotopic tumors were established by co-implantation of equal numbers of PCCs and PSCs in the mouse pancreas. Among the various formulations tested, 5 nm gold nanoparticles coated with gemcitabine, cetuximab and poly-ethylene glycol (PEG) of molecular weight 1000 Da, which we named ACGP441000, demonstrated optimal efficacy in inhibiting tumor growth. The current study reveals an opportunity to target PCCs and PSCs simultaneously, by exploiting their overexpression of EGFR as a target, in order to inhibit pancreatic cancer growth.

Pleiotropic physiological functions of Piezo1 in human body and its effect on malignant behavior of tumors

Mechanosensitive ion channel protein 1 (Piezo1) is a large homotrimeric membrane protein. Piezo1 has various effects and plays an important and irreplaceable role in the maintenance of human life activities and homeostasis of the internal environment. In addition, recent studies have shown that Piezo1 plays a vital role in tumorigenesis, progression, malignancy and clinical prognosis. Piezo1 is involved in regulating the malignant behaviors of a variety of tumors, including cellular metabolic reprogramming, unlimited proliferation, inhibition of apoptosis, maintenance of stemness, angiogenesis, invasion and metastasis. Moreover, Piezo1 regulates tumor progression by affecting the recruitment, activation, and differentiation of multiple immune cells. Therefore, Piezo1 has excellent potential as an anti-tumor target. The article reviews the diverse physiological functions of Piezo1 in the human body and its major cellular pathways during disease development, and describes in detail the specific mechanisms by which Piezo1 affects the malignant behavior of tumors and its recent progress as a new target for tumor therapy, providing new perspectives for exploring more potential effects on physiological functions and its application in tumor therapy.

Glutamine Supplementation as an Anticancer Strategy: A Potential Therapeutic Alternative to the Convention

Glutamine, a multifaceted nonessential/conditionally essential amino acid integral to cellular metabolism and immune function, holds pivotal importance in the landscape of cancer therapy. This review delves into the intricate dynamics surrounding both glutamine antagonism strategies and glutamine supplementation within the context of cancer treatment, emphasizing the critical role of glutamine metabolism in cancer progression and therapy. Glutamine antagonism, aiming to disrupt tumor growth by targeting critical metabolic pathways, is challenged by the adaptive nature of cancer cells and the complex metabolic microenvironment, potentially compromising its therapeutic efficacy. In contrast, glutamine supplementation supports immune function, improves gut integrity, alleviates treatment-related toxicities, and improves patient well-being. Moreover, recent studies highlighted its contributions to epigenetic regulation within cancer cells and its potential to bolster anti-cancer immune functions. However, glutamine implementation necessitates careful consideration of potential interactions with ongoing treatment regimens and the delicate equilibrium between supporting normal cellular function and promoting tumorigenesis. By critically assessing the implications of both glutamine antagonism strategies and glutamine supplementation, this review aims to offer comprehensive insights into potential therapeutic strategies targeting glutamine metabolism for effective cancer management.

The Effect of Substrate Properties on Cellular Behavior and Nanoparticle Uptake in Human Fibroblasts and Epithelial Cells

The delivery of nanomedicines into cells holds enormous therapeutic potential; however little is known regarding how the extracellular matrix (ECM) can influence cell-nanoparticle (NP) interactions. Changes in ECM organization and composition occur in several pathophysiological states, including fibrosis and tumorigenesis, and may contribute to disease progression. We show that the physical characteristics of cellular substrates, that more closely resemble the ECM in vivo, can influence cell behavior and the subsequent uptake of NPs. Electrospinning was used to create two different substrates made of soft polyurethane (PU) with aligned and non-aligned nanofibers to recapitulate the ECM in two different states. To investigate the impact of cell-substrate interaction, A549 lung epithelial cells and MRC-5 lung fibroblasts were cultured on soft PU membranes with different alignments and compared against stiff tissue culture plastic (TCP)/glass. Both cell types could attach and grow on both PU membranes with no signs of cytotoxicity but with increased cytokine release compared with cells on the TCP. The uptake of silica NPs increased more than three-fold in fibroblasts but not in epithelial cells cultured on both membranes. This study demonstrates that cell-matrix interaction is substrate and cell-type dependent and highlights the importance of considering the ECM and tissue mechanical properties when designing NPs for effective cell targeting and treatment.

A Nutrient-Deficient Microenvironment Facilitates Ferroptosis Resistance via the FAM60A-PPAR Axis in Pancreatic Ductal Adenocarcinoma

Ferroptosis, a nonapoptotic form of cell death, is an emerging potential therapeutic target for various diseases, including cancer. However, the role of ferroptosis in pancreatic cancer remains poorly understood. Pancreatic ductal adenocarcinoma (PDAC) is characterized by a poor prognosis and chemotherapy resistance, attributed to its high Kirsten rats arcomaviral oncogene homolog mutation rate and severe nutritional deficits resulting from a dense stroma. Several studies have linked rat sarcoma (RAS) mutations to ferroptosis, suggesting that inducing ferroptosis may be an effective strategy against oncogenic RAS-bearing tumors. We investigated the role of Family With Sequence Similarity 60 Member A (FAM60A) in this study, a protein closely associated with a poor prognosis and highly expressed in PDAC and tumor tissue from KrasG12D/+;Trp53R172H/+; Pdx1-Cre mice, in regulating ferroptosis, tumor growth, and gemcitabine sensitivity in vitro and in vivo. Our results demonstrate that FAM60A regulates 3 essential metabolic enzymes, ACSL1/4 and GPX4, to protect PDAC cells from ferroptosis. Furthermore, we found that YY1 transcriptionally regulates FAM60A expression by promoting its transcription, and the Hippo-YY1 pathway is restricted in the low-amino-acid milieu in the context of nutrient deprivation, leading to downstream suppression of peroxisome proliferator-activated receptor and ACSL1/4 and activation of GPX4 pathways. Importantly, FAM60A knockdown sensitized PDAC cells to gemcitabine treatment. A new understanding of FAM60A transcriptional regulation pattern in PDAC and its dual function in ferroptosis reliever and chemotherapy resistance is provided by our study. Targeting FAM60A may therefore offer a promising therapeutic approach for PDAC by simultaneously addressing 2 major features of the disease (high RAS mutation rate and tumor microenvironment nutrient deficiency) and preventing tumor cell metabolic adaptation.

Regulation of antioxidants in cancer

Scientists in this field often joke, "If you don't have a mechanism, say it's ROS." Seemingly connected to every biological process ever described, reactive oxygen species (ROS) have numerous pleiotropic roles in physiology and disease. In some contexts, ROS act as secondary messengers, controlling a variety of signaling cascades. In other scenarios, they initiate damage to macromolecules. Finally, in their worst form, ROS are deadly to cells and surrounding tissues. A set of molecules with detoxifying abilities, termed antioxidants, is the direct counterpart to ROS. Notably, antioxidants exist in the public domain, touted as a "cure-all" for diseases. Research has disproved many of these claims and, in some cases, shown the opposite. Of all the diseases, cancer stands out in its paradoxical relationship with antioxidants. Although the field has made numerous strides in understanding the roles of antioxidants in cancer, many questions remain.

The aging tumor metabolic microenvironment

Despite the higher incidence of cancer with increasing age, few preclinical or clinical studies incorporate age. This, coupled with an aging world population, requires that we improve our understanding of how aging affects cancer development, progression, and treatment. One key area will be how the tumor microenvironment (TME) changes with age. Metabolite levels are an essential component of the TME, and they are affected by the metabolic requirements of the cells present and systemic metabolite availability. These factors are affected by aging, causing different TME metabolic states between young and older adults. In this review, we will summarize what is known about how aging impacts the TME metabolic state, and suggest how we can improve our understanding of it.

Monocarboxylate Transporter-1 (MCT1)-Mediated Lactate Uptake Protects Pancreatic Adenocarcinoma Cells from Oxidative Stress during Glutamine Scarcity Thereby Promoting Resistance against Inhibitors of Glutamine Metabolism

Metabolic compartmentalization of stroma-rich tumors, like pancreatic ductal adenocarcinoma (PDAC), greatly contributes to malignancy. This involves cancer cells importing lactate from the microenvironment (reverse Warburg cells) through monocarboxylate transporter-1 (MCT1) along with substantial phenotype alterations. Here, we report that the reverse Warburg phenotype of PDAC cells compensated for the shortage of glutamine as an essential metabolite for redox homeostasis. Thus, oxidative stress caused by glutamine depletion led to an Nrf2-dependent induction of MCT1 expression in pancreatic T3M4 and A818-6 cells. Moreover, greater MCT1 expression was detected in glutamine-scarce regions within tumor tissues from PDAC patients. MCT1-driven lactate uptake supported the neutralization of reactive oxygen species excessively produced under glutamine shortage and the resulting drop in glutathione levels that were restored by the imported lactate. Consequently, PDAC cells showed greater survival and growth under glutamine depletion when utilizing lactate through MCT1. Likewise, the glutamine uptake inhibitor V9302 and glutaminase-1 inhibitor CB839 induced oxidative stress in PDAC cells, along with cell death and cell cycle arrest that were again compensated by MCT1 upregulation and forced lactate uptake. Our findings show a novel mechanism by which PDAC cells adapt their metabolism to glutamine scarcity and by which they develop resistance against anticancer treatments based on glutamine uptake/metabolism inhibition.

Tumor microenvironmental nutrients, cellular responses, and cancer

Over the last two decades, the rapidly expanding field of tumor metabolism has enhanced our knowledge of the impact of nutrient availability on metabolic reprogramming in cancer. Apart from established roles in cancer cells themselves, various nutrients, metabolic enzymes, and stress responses are key to the activities of tumor microenvironmental immune, fibroblastic, endothelial, and other cell types that support malignant transformation. In this article, we review our current understanding of how nutrient availability affects metabolic pathways and responses in both cancer and "stromal" cells, by dissecting major examples and their regulation of cellular activity. Understanding the relationship of nutrient availability to cellular behaviors in the tumor ecosystem will broaden the horizon of exploiting novel therapeutic vulnerabilities in cancer.

Targeting CaMKK2 Inhibits Actin Cytoskeletal Assembly to Suppress Cancer Metastasis

Triple-negative breast cancers (TNBC) tend to become invasive and metastatic at early stages in their development. Despite some treatment successes in early-stage localized TNBC, the rate of distant recurrence remains high, and long-term survival outcomes remain poor. In a search for new therapeutic targets for this disease, we observed that elevated expression of the serine/threonine kinase calcium/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) is highly correlated with tumor invasiveness. In validation studies, genetic disruption of CaMKK2 expression or inhibition of its activity with small molecule inhibitors disrupted spontaneous metastatic outgrowth from primary tumors in murine xenograft models of TNBC. High-grade serous ovarian cancer (HGSOC), a high-risk, poor prognosis ovarian cancer subtype, shares many features with TNBC, and CaMKK2 inhibition effectively blocked metastatic progression in a validated xenograft model of this disease. Mechanistically, CaMKK2 increased the expression of the phosphodiesterase PDE1A, which hydrolyzed cyclic guanosine monophosphate (cGMP) to decrease the cGMP-dependent activity of protein kinase G1 (PKG1). Inhibition of PKG1 resulted in decreased phosphorylation of vasodilator-stimulated phosphoprotein (VASP), which in its hypophosphorylated state binds to and regulates F-actin assembly to facilitate cell movement. Together, these findings establish a targetable CaMKK2-PDE1A-PKG1-VASP signaling pathway that controls cancer cell motility and metastasis by impacting the actin cytoskeleton. Furthermore, it identifies CaMKK2 as a potential therapeutic target that can be exploited to restrict tumor invasiveness in patients diagnosed with early-stage TNBC or localized HGSOC.

SIGNIFICANCE

CaMKK2 regulates actin cytoskeletal dynamics to promote tumor invasiveness and can be inhibited to suppress metastasis of breast and ovarian cancer, indicating CaMKK2 inhibition as a therapeutic strategy to arrest disease progression.

Discovery and Targeting of a Noncanonical Mechanism of Sarcoma Resistance to ADI-PEG20 Mediated by the Microenvironment

PURPOSE

Many cancers lack argininosuccinate synthetase 1 (ASS1), the rate-limiting enzyme of arginine biosynthesis. This deficiency causes arginine auxotrophy, targetable by extracellular arginine-degrading enzymes such as ADI-PEG20. Long-term tumor resistance has thus far been attributed solely to ASS1 reexpression. This study examines the role of ASS1 silencing on tumor growth and initiation and identifies a noncanonical mechanism of resistance, aiming to improve clinical responses to ADI-PEG20.

EXPERIMENTAL DESIGN

Tumor initiation and growth rates were measured for a spontaneous Ass1 knockout (KO) murine sarcoma model. Tumor cell lines were generated, and resistance to arginine deprivation therapy was studied in vitro and in vivo.

RESULTS

Conditional Ass1 KO affected neither tumor initiation nor growth rates in a sarcoma model, contradicting the prevalent idea that ASS1 silencing confers a proliferative advantage. Ass1 KO cells grew robustly through arginine starvation in vivo, while ADI-PEG20 remained completely lethal in vitro, evidence that pointed toward a novel mechanism of resistance mediated by the microenvironment. Coculture with Ass1-competent fibroblasts rescued growth through macropinocytosis of vesicles and/or cell fragments, followed by recycling of protein-bound arginine through autophagy/lysosomal degradation. Inhibition of either macropinocytosis or autophagy/lysosomal degradation abrogated this growth support effect in vitro and in vivo.

CONCLUSIONS

Noncanonical, ASS1-independent tumor resistance to ADI-PEG20 is driven by the microenvironment. This mechanism can be targeted by either the macropinocytosis inhibitor imipramine or the autophagy inhibitor chloroquine. These safe, widely available drugs should be added to current clinical trials to overcome microenvironmental arginine support of tumors and improve patient outcomes.

CAFs targeted ultrasound-responsive nanodroplets loaded V9302 and GLULsiRNA to inhibit melanoma growth via glutamine metabolic reprogramming and tumor microenvironment remodeling

Despite rapid advances in metabolic therapies over the past decade, their efficacy in melanoma has been modest, largely due to the interaction between cancer-associated fibroblasts (CAFs) and cancer cells to promote cancer growth. Altering the tumor microenvironment (TME) is challenging and elusive. CAFs is critical for glutamine deprivation survival in melanoma. In this research, we assembled a CAFs-targeted, controlled-release nanodroplets for the combined delivery of the amino acid transporter ASCT2 (SLC1A5) inhibitor V9302 and GLULsiRNA (siGLUL). The application of ultrasound-targeted microbubble disruption (UTMD) allows for rapid release of V9302 and siGLUL, jointly breaking the glutamine metabolism interaction between CAFs and cancer cells on one hand, on the other hand, blocking activated CAFs and reducing the expression of extracellular matrix (ECM) to facilitate drug penetration. In addition, ultrasound stimulation made siGLUL more accessible to tumor cells and CAFs, downregulating GLUL expression in both cell types. FH-V9302-siGLUL-NDs also serve as contrast-enhanced ultrasound imaging agents for tumor imaging. Our study developed and reported FH-NDs as nanocarriers for V9302 and siGLUL, demonstrating that FH-V9302-siGLUL-NDs have potential bright future applications for integrated diagnostic therapy. Graphical Abstract.

TRPM2 Mediates Hepatic Ischemia-Reperfusion Injury via Ca2+-Induced Mitochondrial Lipid Peroxidation through Increasing ALOX12 Expression

Hepatic ischemia-reperfusion (IR) injury is a serious clinical problem that complicates liver resection and transplantation. Despite recent advances in understanding of the pathophysiology of hepatic IR injury, effective interventions and therapeutics are still lacking. Here, we examined the role of transient receptor potential melastatin 2 (TRPM2), a Ca²⁺-permeable, non-selective cation channel, in mediating hepatic IR injury. Our data showed that TRPM2 deficiency attenuated IR-induced liver dysfunction, inflammation, and cell death in mice. Moreover, RNA sequencing analysis indicated that TRPM2-induced IR injury occurs via ferroptosis-related pathways. Consistently, as a ferroptosis inducer, (1S,3R)-RSL3 treatment induced mitochondrial dysfunction in hepatocytes and a TRPM2 inhibitor suppressed this. Interestingly, TRPM2-mediated calcium influx caused mitochondrial calcium accumulation via the mitochondrial Ca²⁺-selective uniporter and increased the expression level of arachidonate 12-lipoxygenase (ALOX12), which results in mitochondrial lipid peroxidation during hepatic IR injury. Furthermore, hepatic IR injury-induced ferroptosis was obviously relieved by a TRPM2 inhibitor or calcium depletion, both in vitro and in vivo. Collectively, these findings demonstrate a crucial role for TRPM2-mediated ferroptosis in hepatic IR injury via increased Ca²⁺-induced ALOX12 expression, indicating that pharmacological inhibition of TRPM2 may provide an effective therapeutic strategy for hepatic IR injury-related diseases, such as during liver resection and transplantation.

Gold Nanoparticles Inhibit Macropinocytosis by Decreasing KRAS Activation

The RAS-transformed cells utilize macropinocytosis to acquire amino acids to support their uncontrolled growth. However, targeting RAS to inhibit macropinocytosis remains a challenge. Here, we report that gold nanoparticles (GNP) inhibit macropinocytosis by decreasing KRAS activation. Using surface-modified and unmodified GNP, we showed that unmodified GNP specifically sequestered both wild-type and mutant KRAS and inhibited its activation, irrespective of growth factor stimulation, while surface-passivated GNP had no effect. Alteration of KRAS activation is reflected on downstream signaling cascades, macropinocytosis and tumor cell growth in vitro, and two independent preclinical human xenograft models of pancreatic cancer in vivo. The current study demonstrates NP-mediated inhibition of macropinocytosis and KRAS activation and provides translational opportunities to inhibit tumor growth in a number of cancers where activation of KRAS plays a major role.

Endocytosis in cancer and cancer therapy

Endocytosis is a complex process whereby cell surface proteins, lipids and fluid from the extracellular environment are packaged, sorted and internalized into cells. Endocytosis is also a mechanism of drug internalization into cells. There are multiple routes of endocytosis that determine the fate of molecules, from degradation in the lysosomes to recycling back to the plasma membrane. The overall rates of endocytosis and temporal regulation of molecules transiting through endocytic pathways are also intricately linked with signalling outcomes. This process relies on an array of factors, such as intrinsic amino acid motifs and post-translational modifications. Endocytosis is frequently disrupted in cancer. These disruptions lead to inappropriate retention of receptor tyrosine kinases on the tumour cell membrane, changes in the recycling of oncogenic molecules, defective signalling feedback loops and loss of cell polarity. In the past decade, endocytosis has emerged as a pivotal regulator of nutrient scavenging, response to and regulation of immune surveillance and tumour immune evasion, tumour metastasis and therapeutic drug delivery. This Review summarizes and integrates these advances into the understanding of endocytosis in cancer. The potential to regulate these pathways in the clinic to improve cancer therapy is also discussed.

Ca 2+ /Calmodulin Dependent Protein Kinase Kinase-2 (CaMKK2) promotes Protein Kinase G (PKG)-dependent actin cytoskeletal assembly to increase tumor metastasis

Triple-negative breast cancers (TNBCs) tend to become highly invasive early during cancer development. Despite some successes in the initial treatment of patients diagnosed with early-stage localized TNBC, the rate of metastatic recurrence remains high with poor long-term survival outcomes. Here we show that elevated expression of the serine/threonine-kinase, Calcium/Calmodulin (CaM)-dependent protein kinase kinase-2 (CaMKK2), is highly correlated with tumor invasiveness. We determined that genetic disruption of CaMKK2 expression, or inhibition of its activity, disrupted spontaneous metastatic outgrowth from primary tumors in murine xenograft models of TNBC. High-grade serous ovarian cancer (HGSOC), a high-risk, poor-prognosis ovarian cancer subtype, shares many genetic features with TNBC, and importantly, CaMKK2 inhibition effectively blocked metastatic progression in a validated xenograft model of this disease. Probing the mechanistic links between CaMKK2 and metastasis we defined the elements of a new signaling pathway that impacts actin cytoskeletal dynamics in a manner which increases cell migration/invasion and metastasis. Notably, CaMKK2 increases the expression of the phosphodiesterase PDE1A which decreases the cGMP-dependent activity of protein kinase G1 (PKG1). This inhibition of PKG1 results in decreased phosphorylation of Vasodilator-Stimulated Phosphoprotein (VASP), which in its hypophosphorylated state binds to and regulates F-actin assembly to facilitate contraction/cell movement. Together, these data establish a targetable CaMKK2-PDE1A-PKG1-VASP signaling pathway that controls cancer cell motility and metastasis. Further, it credentials CaMKK2 as a therapeutic target that can be exploited in the discovery of agents for use in the neoadjuvant/adjuvant setting to restrict tumor invasiveness in patients diagnosed with early-stage TNBC or localized HGSOC.

Pancreatic cancer: Advances and challenges

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest cancers. Significant efforts have largely defined major genetic factors driving PDAC pathogenesis and progression. Pancreatic tumors are characterized by a complex microenvironment that orchestrates metabolic alterations and supports a milieu of interactions among various cell types within this niche. In this review, we highlight the foundational studies that have driven our understanding of these processes. We further discuss the recent technological advances that continue to expand our understanding of PDAC complexity. We posit that the clinical translation of these research endeavors will enhance the currently dismal survival rate of this recalcitrant disease.

Macropinocytosis: mechanisms and regulation

Macropinocytosis is defined as an actin-dependent but coat- and dynamin-independent endocytic uptake process, which generates large intracellular vesicles (macropinosomes) containing a non-selective sampling of extracellular fluid. Macropinocytosis provides an important mechanism of immune surveillance by dendritic cells and macrophages, but also serves as an essential nutrient uptake pathway for unicellular organisms and tumor cells. This review examines the cell biological mechanisms that drive macropinocytosis, as well as the complex signaling pathways - GTPases, lipid and protein kinases and phosphatases, and actin regulatory proteins - that regulate macropinosome formation, internalization, and disposition.

Cytoskeletal association of ATP citrate lyase controls the mechanodynamics of macropinocytosis

Macropinocytosis is an actin-dependent mode of nonselective endocytosis that mediates the uptake of extracellular fluid-phase cargoes. It is now well recognized that tumor cells exploit macropinocytosis to internalize macromolecules that can be catabolized and used to support cell growth and proliferation under nutrient-limiting conditions. Therefore, the identification of molecular mechanisms that control macropinocytosis is fundamental to the understanding of the metabolic adaptive landscape of tumor cells. Here, we report that the acetyl-CoA-producing enzyme, ATP citrate lyase (ACLY), is a key regulator of macropinocytosis and describes a heretofore-unappreciated association of ACLY with the actin cytoskeleton. The cytoskeletal tethering of ACLY is required for the spatially defined acetylation of heterodimeric actin capping protein, which we identify as an essential mediator of the actin remodeling events that drive membrane ruffling and macropinocytosis. Furthermore, we identify a requirement for mitochondrial-derived citrate, an ACLY substrate, for macropinocytosis, and show that mitochondria traffic to cell periphery regions juxtaposed to plasma membrane ruffles. Collectively, these findings establish a mode of metabolite compartmentalization that supports the spatiotemporal modulation of membrane-cytoskeletal interactions required for macropinocytosis by coupling regional acetyl-CoA availability with dynamic protein acetylation.

Inhibition of Macropinocytosis Enhances the Sensitivity of Osteosarcoma Cells to Benzethonium Chloride

Osteosarcoma (OS) is a primary malignant tumor of bone. Chemotherapy is one of the crucial approaches to prevent its metastasis and improve prognosis. Despite continuous improvements in the clinical treatment of OS, tumor resistance and metastasis remain dominant clinical challenges. Macropinocytosis, a form of non-selective nutrient endocytosis, has received increasing attention as a novel target for cancer therapy, yet its role in OS cells remains obscure. Benzethonium chloride (BZN) is an FDA-approved antiseptic and bactericide with broad-spectrum anticancer effects. Here, we described that BZN suppressed the proliferation, migration, and invasion of OS cells in vitro and in vivo, but simultaneously promoted the massive accumulation of cytoplasmic vacuoles as well. Mechanistically, BZN repressed the ERK1/2 signaling pathway, and the ERK1/2 activator partially neutralized the inhibitory effect of BZN on OS cells. Subsequently, we demonstrated that vacuoles originated from macropinocytosis and indicated that OS cells might employ macropinocytosis as a compensatory survival mechanism in response to BZN. Remarkably, macropinocytosis inhibitors enhanced the anti-OS effect of BZN in vitro and in vivo. In conclusion, our results suggest that BZN may inhibit OS cells by repressing the ERK1/2 signaling pathway and propose a potential strategy to enhance the BZN-induced inhibitory effect by suppressing macropinocytosis.

Tumor Microenvironment in Pancreatic Cancer Pathogenesis and Therapeutic Resistance

Pancreatic ductal adenocarcinoma (PDAC) features a prominent stromal microenvironment with remarkable cellular and spatial heterogeneity that meaningfully impacts disease biology and treatment resistance. Recent advances in tissue imaging capabilities, single-cell analytics, and disease modeling have shed light on organizing principles that shape the stromal complexity of PDAC tumors. These insights into the functional and spatial dependencies that coordinate cancer cell biology and the relationships that exist between cells and extracellular matrix components present in tumors are expected to unveil therapeutic vulnerabilities. We review recent advances in the field and discuss current understandings of mechanisms by which the tumor microenvironment shapes PDAC pathogenesis and therapy resistance.

Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment

Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.

SGC-CAMKK2-1: A Chemical Probe for CAMKK2

The serine/threonine protein kinase calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) plays critical roles in a range of biological processes. Despite its importance, only a handful of inhibitors of CAMKK2 have been disclosed. Having a selective small molecule tool to interrogate this kinase will help demonstrate that CAMKK2 inhibition can be therapeutically beneficial. Herein, we disclose SGC-CAMKK2-1, a selective chemical probe that targets CAMKK2.

Pancreatic cancer and fibrosis: Targeting metabolic reprogramming and crosstalk of cancer-associated fibroblasts in the tumor microenvironment

Pancreatic cancer is one of the most dangerous types of cancer today, notable for its low survival rate and fibrosis. Deciphering the cellular composition and intercellular interactions in the tumor microenvironment (TME) is a necessary prerequisite to combat pancreatic cancer with precision. Cancer-associated fibroblasts (CAFs), as major producers of extracellular matrix (ECM), play a key role in tumor progression. CAFs display significant heterogeneity and perform different roles in tumor progression. Tumor cells turn CAFs into their slaves by inducing their metabolic dysregulation, exacerbating fibrosis to acquire drug resistance and immune evasion. This article reviews the impact of metabolic reprogramming, effect of obesity and cellular crosstalk of CAFs and tumor cells on fibrosis and describes relevant therapies targeting the metabolic reprogramming.

Neuronal CaMKK2 promotes immunosuppression and checkpoint blockade resistance in glioblastoma

Glioblastoma (GBM) is notorious for its immunosuppressive tumor microenvironment (TME) and is refractory to immune checkpoint blockade (ICB). Here, we identify calmodulin-dependent kinase kinase 2 (CaMKK2) as a driver of ICB resistance. CaMKK2 is highly expressed in pro-tumor cells and is associated with worsened survival in patients with GBM. Host CaMKK2, specifically, reduces survival and promotes ICB resistance. Multimodal profiling of the TME reveals that CaMKK2 is associated with several ICB resistance-associated immune phenotypes. CaMKK2 promotes exhaustion in CD8⁺ T cells and reduces the expansion of effector CD4⁺ T cells, additionally limiting their tumor penetrance. CaMKK2 also maintains myeloid cells in a disease-associated microglia-like phenotype. Lastly, neuronal CaMKK2 is required for maintaining the ICB resistance-associated myeloid phenotype, is deleterious to survival, and promotes ICB resistance. Our findings reveal CaMKK2 as a contributor to ICB resistance and identify neurons as a driver of immunotherapeutic resistance in GBM.

Cancer-associated fibroblasts: Origin, function, imaging, and therapeutic targeting

The tumor microenvironment (TME) is emerging as one of the primary barriers in cancer therapy. Cancer-associated fibroblasts (CAF) are a common inhabitant of the TME in several tumor types and play a critical role in tumor progression and drug resistance via different mechanisms such as desmoplasia, angiogenesis, immune modulation, and cancer metabolism. Due to their abundance and significance in pro-tumorigenic mechanisms, CAF are gaining attention as a diagnostic target as well as to improve the efficacy of cancer therapy by their modulation. In this review, we highlight existing imaging techniques that are used for the visualization of CAF and CAF-induced fibrosis and provide an overview of compounds that are known to modulate CAF activity. Subsequently, we also discuss CAF-targeted and CAF-modulating nanocarriers. Finally, our review addresses ongoing challenges and provides a glimpse into the prospects that can spearhead the transition of CAF-targeted therapies from opportunity to reality.

Targeting the Metabolic Rewiring in Pancreatic Cancer and Its Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with only a few effective therapeutic options. A characteristic feature of PDAC is its unique tumor microenvironment (TME), termed desmoplasia, which shows extensive fibrosis and extracellular matrix deposition, generating highly hypoxic and nutrient-deprived conditions within the tumor. To thrive in this harsh TME, PDAC undergoes extensive metabolic rewiring that includes the altered use of glucose and glutamine, constitutive activation of autophagy-lysosomal pathways, and nutrient acquisition from host cells in the TME. Notably, these properties support PDAC metabolism and mediate therapeutic resistance, including immune suppression. A deeper understanding of the unique metabolic properties of PDAC and its TME may aid in the development of novel therapeutic strategies against this deadly disease.

Pancreatic ductal adenocarcinoma cells regulated the gemcitabine-resistance function of CAFs by LINC00460

Pancreatic ductal adenocarcinoma (PDAC) is a highly fatal malignancy with extremely poor prognosis. Gemcitabine resistance is a major challenge in the treatment of PDAC. Here, we showed that LINC00460 was associated with the response to gemcitabine both in PDAC patients and PDAC‐PDX. After knocking down LINC00460 in PDAC tumor cells, results of RNA sequencing followed by gene ontology analysis indicated that LINC00460 influenced the activity of growth factors and modified the extracellular matrix. FISH showed that LINC00460 is mostly located in the cytoplasm. Results of RNA pull‐down, LC–MS/MS, RIP, and immunoblotting confirmed that LINC00460 could directly bind to PDAP1. Furthermore, we demonstrated that LINC00460 mediated the cellular communication of PDAC tumor cells and CAFs by PDAP1/PDGFA/PDGFR signaling pathway and regulated the gemcitabine‐resistance function of CAFs, which could be reversed by treatment with a PDGFR inhibitor (crenolanib). PDAC‐PDX tumors with lower expression of LINC00460 showed a better response to gemcitabine plus crenolanib treatment. Our finding supported the application of LINC00460 in precision medicine that uses gemcitabine plus crenolanib to treat PDAC with low expression of LINC00460.