Fibroblasts in cancer: Unity in heterogeneity

Integrating bulk and single-cell sequencing reveals metastasis-associated CAFs in head and neck squamous cell carcinoma

AIMS

Cancer-associated fibroblasts (CAFs) have been shown to promote the metastasis of head and neck squamous cell carcinoma (HNSCC), but the underlying mechanisms remain unclear. The purpose of this study is to identify gene in CAFs that are associated with metastasis and to preliminarily validate its impact on the metastasis of HNSCC.

MATERIALS AND METHODS

Scissor analysis was utilized to process single-cell and bulk RNA sequencing datasets, identifying genes associated with the metastasis of HNSCC through differential gene expression analysis. A risk model was constructed using LASSO regression analysis. Quantitative real time-PCR and Western blot were employed to measure mRNA and protein expressions, respectively. Multiplex immunohistochemistry (mIHC) was used to assess protein expression in CAFs. siRNA was utilized to achieve gene knockdown. CCK-8 and Transwell assays were employed to evaluate the biological characteristics of HNSCC cells.

KEY FINDINGS

Compare to the nonmetastatic primary CAFs (nmCAFs), tissue inhibitors of metalloproteinase-1 (TIMP1) was founded to be overexpressed in the cells and tissues of metastatic primary CAFs (mCAFs). Knocking down TIMP1 in CAFs can signifucantly inhibit the proliferation, invasion, and migration of HNSCC cells.

SIGNIFICANCE

CAFs facilitate HNSCC cell metastasis by upregulating TIMP1, highlighting TIMP1 as a potential therapeutic target in HNSCC metastasis management.

Targeting the devil: Strategies against cancer-associated fibroblasts in colorectal cancer

Cancer-associated fibroblasts (CAFs), as significant constituents of the tumor microenvironment (TME), play a pivotal role in the progression of cancers, including colorectal cancer (CRC). In this comprehensive review, we presented the origins and activation mechanisms of CAFs in CRC, elaborating on how CAFs drive tumor progression through their interactions with CRC cells, immune cells, vascular endothelial cells, and the extracellular matrix within the TME. We systematically outline the intricate web of interactions among CAFs, tumor cells, and other TME components, and based on this complex interplay, we summarize various therapeutic strategies designed to target CAFs in CRC. It is also essential to recognize that CAFs represent a highly heterogeneous group, encompassing various subtypes such as myofibroblastic CAF (myCAF), inflammatory CAF (iCAF), antigen-presenting CAF (apCAF), vessel-associated CAF (vCAF). Herein, we provide a summary of studies investigating the heterogeneity of CAFs in CRC and the characteristic expression patterns of each subtype. While the majority of CAFs contribute to the exacerbation of CRC malignancy, recent findings have revealed specific subtypes that exert inhibitory effects on CRC progression. Nevertheless, the comprehensive landscape of CAF heterogeneity still awaits exploration. We also highlight pivotal unanswered questions that need to be addressed before CAFs can be recognized as feasible targets for cancer treatment. In conclusion, the aim of our review is to elucidate the significance and challenges of advancing in-depth research on CAFs, while outlining the pathway to uncover the complex roles of CAFs in CRC and underscore their significant potential as therapeutic targets.

Mechanistic insights into mesenchymal-amoeboid transition as an intelligent cellular adaptation in cancer metastasis and resistance

Malignant cell plasticity is an important hallmark of tumor biology and crucial for metastasis and resistance. Cell plasticity lets cancer cells adapt to and escape the therapeutic strategies, which is the leading cause of cancer patient mortality. Epithelial cells acquire mobility via epithelial-mesenchymal transition (EMT), whereas mesenchymal cells enhance their migratory ability and clonogenic potential by acquiring amoeboid characteristics through mesenchymal-amoeboid transition (MAT). Tumor formation, progression, and metastasis depend on the tumor microenvironment (TME), a complex ecosystem within and around a tumor. Through increased migration and metastasis of cancer cells, the TME also contributes to malignancy. This review underscores the distinction between invasion pattern morphological manifestations and the diverse structures found within the TME. Furthermore, the mechanisms by which amoeboid-associated characteristics promote resistance and metastasis and how these mechanisms may represent therapeutic opportunities are discussed.

Survival strategies: How tumor hypoxia microenvironment orchestrates angiogenesis

During tumor development, the tumor itself must continuously generate new blood vessels to meet their growth needs while also allowing for tumor invasion and metastasis. One of the most common features of tumors is hypoxia, which drives the process of tumor angiogenesis by regulating the tumor microenvironment, thus adversely affecting the prognosis of patients. In addition, to overcome unsuitable environments for growth, such as hypoxia, nutrient deficiency, hyperacidity, and immunosuppression, the tumor microenvironment (TME) coordinates angiogenesis in several ways to restore the supply of oxygen and nutrients and to remove metabolic wastes. A growing body of research suggests that tumor angiogenesis and hypoxia interact through a complex interplay of crosstalk, which is inextricably linked to the TME. Here, we review the TME's positive contribution to angiogenesis from an angiogenesis-centric perspective while considering the objective impact of hypoxic phenotypes and the status and limitations of current angiogenic therapies.

Advances in preclinical assessment of therapeutic targets for bladder cancer precision medicine

PURPOSE OF REVIEW

Bladder cancer incidence is on the rise, and until recently, there has been little to no change in treatment regimens over the last 40 years. Hence, it is imperative to work on strategies and approaches to untangle the complexity of intra- and inter-tumour heterogeneity of bladder cancer with the aim of improving patient-specific care and treatment outcomes. The focus of this review is therefore to highlight novel targets, advances, and therapy approaches for bladder cancer patients.

RECENT FINDINGS

The success of combining an antibody-drug conjugate (ADC) with immunotherapy has been recently hailed as a game changer in treating bladder cancer patients. Hence, interest in other ADCs as a treatment option is also rife. Furthermore, strategies to overcome chemoresistance to standard therapy have been described recently. In addition, other studies showed that targeting genomic alterations (e.g. mutations in FGFR3 , DNA damage repair genes and loss of the Y chromosome) could also be helpful as prognostic and treatment stratification biomarkers. The use of single-cell RNA sequencing approaches has allowed better characterisation of the tumour microenvironment and subsequent identification of novel targets. Functional precision medicine could be another avenue to improve and guide personalized treatment options.

SUMMARY

Several novel preclinical targets and treatment options have been described recently. The validation of these advances will lead to the development and implementation of robust personalized treatment regimens for bladder cancer patients.

Fibronectin-Targeting Dual-Modal MR/NIRF Imaging Contrast Agents for Diagnosis of Gastric Cancer and Peritoneal Metastasis

The prevalence and fatality rates of gastric cancer (GC) remain elevated, with advanced stages presenting a grim prognosis. Noninvasive diagnosis of GC cancer often proves challenging until the disease has progressed to an advanced stage or metastasized. Initially, the level of fibronectin (FN) in cancer-associated fibroblasts (CAFs) of GC was at least 3.7 times higher than that in normal fibroblasts. Herein, two FN-targeting magnetic resonance/near-infrared fluorescence (MR/NIRF) imaging contrast agents were developed to detect GC and peritoneal metastasis noninvasively. The probes CREKA-Cy7-(Gd-DOTA) and CREKA-Cy7-(Gd-DOTA)3 demonstrated significant FN-targeting capability (with dissociation constants of 1.0 and 2.1 mM) and effective MR imaging performance (with proton relaxivity values of 9.66 and 27.44 mM-1 s-1 at 9.4 T, 37 °C). In vivo imaging revealed a high signal-to-noise ratio and successful visualization of GC metastasis using NIRF imaging as well as successful tumor detection in MR imaging. Therefore, this study highlights the potential of FN-targeting probes for GC diagnosis and aids in the advancement of new diagnostic strategies for the clinical detection of GC.

Tumor initiation and early tumorigenesis: molecular mechanisms and interventional targets

Tumorigenesis is a multistep process, with oncogenic mutations in a normal cell conferring clonal advantage as the initial event. However, despite pervasive somatic mutations and clonal expansion in normal tissues, their transformation into cancer remains a rare event, indicating the presence of additional driver events for progression to an irreversible, highly heterogeneous, and invasive lesion. Recently, researchers are emphasizing the mechanisms of environmental tumor risk factors and epigenetic alterations that are profoundly influencing early clonal expansion and malignant evolution, independently of inducing mutations. Additionally, clonal evolution in tumorigenesis reflects a multifaceted interplay between cell-intrinsic identities and various cell-extrinsic factors that exert selective pressures to either restrain uncontrolled proliferation or allow specific clones to progress into tumors. However, the mechanisms by which driver events induce both intrinsic cellular competency and remodel environmental stress to facilitate malignant transformation are not fully understood. In this review, we summarize the genetic, epigenetic, and external driver events, and their effects on the co-evolution of the transformed cells and their ecosystem during tumor initiation and early malignant evolution. A deeper understanding of the earliest molecular events holds promise for translational applications, predicting individuals at high-risk of tumor and developing strategies to intercept malignant transformation.

The G Protein Estrogen Receptor (GPER) is involved in the resistance to the CDK4/6 inhibitor palbociclib in breast cancer

BACKGROUND

The cyclin D1-cyclin dependent kinases (CDK)4/6 inhibitor palbociclib in combination with endocrine therapy shows remarkable efficacy in the management of estrogen receptor (ER)-positive and HER2-negative advanced breast cancer (BC). Nevertheless, resistance to palbociclib frequently arises, highlighting the need to identify new targets toward more comprehensive therapeutic strategies in BC patients.

METHODS

BC cell lines resistant to palbociclib were generated and used as a model system. Gene silencing techniques and overexpression experiments, real-time PCR, immunoblotting and chromatin immunoprecipitation studies as well as cell viability, colony and 3D spheroid formation assays served to evaluate the involvement of the G protein-coupled estrogen receptor (GPER) in the resistance to palbociclib in BC cells. Molecular docking simulations were also performed to investigate the potential interaction of palbociclib with GPER. Furthermore, BC cells co-cultured with cancer-associated fibroblasts (CAFs) isolated from mammary carcinoma, were used to investigate whether GPER signaling may contribute to functional cell interactions within the tumor microenvironment toward palbociclib resistance. Finally, by bioinformatics analyses and k-means clustering on clinical and expression data of large cohorts of BC patients, the clinical significance of novel mediators of palbociclib resistance was explored.

RESULTS

Dissecting the molecular events that characterize ER-positive BC cells resistant to palbociclib, the down-regulation of ERα along with the up-regulation of GPER were found. To evaluate the molecular events involved in the up-regulation of GPER, we determined that the epidermal growth factor receptor (EGFR) interacts with the promoter region of GPER and stimulates its expression toward BC cells resistance to palbociclib treatment. Adding further cues to these data, we ascertained that palbociclib does induce pro-inflammatory transcriptional events via GPER signaling in CAFs. Of note, by performing co-culture assays we demonstrated that GPER contributes to the reduced sensitivity to palbociclib also facilitating the functional interaction between BC cells and main components of the tumor microenvironment named CAFs.

CONCLUSIONS

Overall, our results provide novel insights on the molecular events through which GPER may contribute to palbociclib resistance in BC cells. Additional investigations are warranted in order to assess whether targeting the GPER-mediated interactions between BC cells and CAFs may be useful in more comprehensive therapeutic approaches of BC resistant to palbociclib.

SPDYC serves as a prognostic biomarker related to lipid metabolism and the immune microenvironment in breast cancer

Breast cancer remains the most common malignant carcinoma among women globally and is resistant to several therapeutic agents. There is a need for novel targets to improve the prognosis of patients with breast cancer. Bioinformatics analyses were conducted to explore potentially relevant prognostic genes in breast cancer using The Cancer Genome Atlas (TCGA) and The Gene Expression Omnibus (GEO) databases. Gene subtypes were categorized by machine learning algorithms. The machine learning-related breast cancer (MLBC) score was evaluated through principal component analysis (PCA) of clinical patients' pathological statuses and subtypes. Immune cell infiltration was analyzed using the xCell and CIBERSORT algorithms. Kyoto Encyclopedia of Genes and Genomes enrichment analysis elucidated regulatory pathways related to speedy/RINGO cell cycle regulator family member C (SPDYC) in breast cancer. The biological functions and lipid metabolic status of breast cancer cell lines were validated via quantitative real-time polymerase chain reaction (RT‒qPCR) assays, western blotting, CCK-8 assays, PI‒Annexin V fluorescence staining, transwell assays, wound healing assays, and Oil Red O staining. Key differentially expressed genes (DEGs) in breast cancer from the TCGA and GEO databases were screened and utilized to establish the MLBC score. Moreover, the MLBC score we established was negatively correlated with poor prognosis in breast cancer patients. Furthermore, the impacts of SPDYC on the tumor immune microenvironment and lipid metabolism in breast cancer were revealed and validated. SPDYC is closely related to activated dendritic cells and macrophages and is simultaneously correlated with the immune checkpoints CD47, cytotoxic T lymphocyte antigen-4 (CTLA-4), and poliovirus receptor (PVR). SPDYC strongly correlated with C-C motif chemokine ligand 7 (CCL7), a chemokine that influences breast cancer patient prognosis. A significant relationship was discovered between key genes involved in lipid metabolism and SPDYC, such as ELOVL fatty acid elongase 2 (ELOVL2), malic enzyme 1 (ME1), and squalene epoxidase (SQLE). Potent inhibitors targeting SPDYC in breast cancer were also discovered, including JNK inhibitor VIII, AICAR, and JW-7-52-1. Downregulation of SPDYC expression in vitro decreased proliferation, increased the apoptotic rate, decreased migration, and reduced lipid droplets. SPDYC possibly influences the tumor immune microenvironment and regulates lipid metabolism in breast cancer. Hence, this study identified SPDYC as a pivotal biomarker for developing therapeutic strategies for breast cancer.

Mechanistic Characterization of Cancer-associated Fibroblast Depletion via an Antibody-Drug Conjugate Targeting Fibroblast Activation Protein

Cancer-associated fibroblasts (CAF) are a prominent cell type within the tumor microenvironment (TME) where they are known to promote cancer cell growth and survival, angiogenesis, drug resistance, and immunosuppression. The transmembrane prolyl protease fibroblast activation protein (FAP) is expressed on the surface of highly protumorigenic CAFs found in the stroma of nearly every cancer of epithelial origin. The widespread expression of FAP has made it an attractive therapeutic target based on the underlying hypothesis that eliminating protumorigenic CAFs will disrupt the cross-talk between components of TME resulting in cancer cell death and immune infiltration. This hypothesis, however, has never been directly proven. To eliminate FAP-expressing CAFs, we developed an antibody-drug conjugate using our anti-FAP antibody, huB12, coupled to a monomethyl auristatin E (huB12-MMAE) payload. After determining that huB12 was an effective targeting vector, we found that huB12-MMAE potently eliminated FAP-expressing cells as monocultures in vitro and significantly prolonged survival in vivo using a xenograft engineered to overexpress FAP. We investigated the effects of selectively eliminating CAFs using a layered, open microfluidic cell coculture platform, known as the Stacks. Analysis of mRNA and protein expression found that treatment with huB12-MMAE resulted in the increased secretion of the proinflammatory cytokines IL6 and IL8 by CAFs and an associated increase in expression of proinflammatory genes in cancer cells. We also detected increased secretion of CSF1, a cytokine involved in myeloid recruitment and differentiation. Our findings suggest that the mechanism of FAP-targeted therapies is through effects on the immune microenvironment and antitumor immune response.

SIGNIFICANCE

The direct elimination of FAP-expressing CAFs disrupts the cross-talk with cancer cells leading to a proinflammatory response and alterations in the immune microenvironment and antitumor immune response.

Synthetic retinoid-mediated preconditioning of cancer-associated fibroblasts and macrophages improves cancer response to immune checkpoint blockade

BACKGROUND

The proliferation of cancer-associated fibroblasts (CAFs) hampers drug delivery and anti-tumor immunity, inducing tumor resistance to immune checkpoint blockade (ICB) therapy. However, it has remained a challenge to develop therapeutics that specifically target or modulate CAFs.

METHODS

We investigated the involvement of Meflin+ cancer-restraining CAFs (rCAFs) in ICB efficacy in patients with clear cell renal cell carcinoma (ccRCC) and urothelial carcinoma (UC). We examined the effects of Am80 (a synthetic retinoid) administration on CAF phenotype, the tumor immune microenvironment, and ICB efficacy in cancer mouse models.

RESULTS

High infiltration of Meflin+ CAFs correlated with ICB efficacy in patients with ccRCC and UC. Meflin+ CAF induction by Am80 administration improved ICB efficacy in the mouse models of cancer. Am80 exerted this effect when administered prior to, but not concomitant with, ICB therapy in wild-type but not Meflin-deficient mice. Am80-mediated induction of Meflin+ CAFs was associated with increases in antibody delivery and M1-like tumor-associated macrophage (TAM) infiltration. Finally, we showed the role of Chemerin produced from CAFs after Am80 administration in the induction of M1-like TAMs.

CONCLUSION

Our data suggested that Am80 administration prior to ICB therapy increases the number of Meflin+ rCAFs and ICB efficacy by inducing changes in TAM phenotype.

A pan-cancer single-cell transcriptional analysis of antigen-presenting cancer-associated fibroblasts in the tumor microenvironment

Background

Cancer-associated fibroblasts (CAFs) are the primary stromal cells found in tumor microenvironment, and display high plasticity and heterogeneity. By using single-cell RNA-seq technology, researchers have identified various subpopulations of CAFs, particularly highlighting a recently identified subpopulation termed antigen-presenting CAFs (apCAFs), which are largely unknown.

Methods

We collected datasets from public databases for 9 different solid tumor types to analyze the role of apCAFs in the tumor microenvironment.

Results

Our data revealed that apCAFs, likely originating mainly from normal fibroblast, are commonly found in different solid tumor types and generally are associated with anti-tumor effects. apCAFs may be associated with the activation of CD4+ effector T cells and potentially promote the survival of CD4+ effector T cells through the expression of C1Q molecules. Moreover, apCAFs exhibited highly enrichment of transcription factors RUNX3 and IKZF1, along with increased glycolytic metabolism.

Conclusions

Taken together, these findings offer novel insights into a deeper understanding of apCAFs and the potential therapeutic implications for apCAFs targeted immunotherapy in cancer.

Recent advances in understanding the immune microenvironment in ovarian cancer

The occurrence of ovarian cancer (OC) is a major factor in women's mortality rates. Despite progress in medical treatments, like new drugs targeting homologous recombination deficiency, survival rates for OC patients are still not ideal. The tumor microenvironment (TME) includes cancer cells, fibroblasts linked to cancer (CAFs), immune-inflammatory cells, and the substances these cells secrete, along with non-cellular components in the extracellular matrix (ECM). First, the TME mainly plays a role in inhibiting tumor growth and protecting normal cell survival. As tumors progress, the TME gradually becomes a place to promote tumor cell progression. Immune cells in the TME have attracted much attention as targets for immunotherapy. Immune checkpoint inhibitor (ICI) therapy has the potential to regulate the TME, suppressing factors that facilitate tumor advancement, reactivating immune cells, managing tumor growth, and extending the survival of patients with advanced cancer. This review presents an outline of current studies on the distinct cellular elements within the OC TME, detailing their main functions and possible signaling pathways. Additionally, we examine immunotherapy rechallenge in OC, with a specific emphasis on the biological reasons behind resistance to ICIs.

Elimination of radiation-induced senescent cancer cells and stromal cells in vitro by near-infrared photoimmunotherapy

INTRODUCTION

Therapy-induced senescent cancer and stromal cells secrete cytokines and growth factors to promote tumor progression. Therefore, senescent cells may be novel targets for tumor treatment. Near-infrared photoimmunotherapy (NIR-PIT) is a highly tumor-selective therapy that employs conjugates of a molecular-targeting antibody and photoabsorber. Thus, NIR-PIT has the potential to be applied as a novel senolytic therapy. This study aims to investigate the efficacy of NIR-PIT treatment on senescent cancer and stromal cells.

METHODS

Two cancer cell lines (human lung adenocarcinoma A549 cells and human pancreatic cancer MIA PaCa-2 cells) and two normal cell lines (mouse fibroblast transfected with human epidermal growth factor receptor 2 [HER2] cells and human fibroblast WI38 cells) were used. The cytotoxicity of NIR-PIT was evaluated using anti-epidermal growth factor receptor (EGFR) antibody panitumumab and anti-HER2 antibody transtuzumab.

RESULTS

Cellular senescence was induced in A549 and MIA PaCa-2 cells by 10 Gy γ-irradiation. The up-regulation of cellular senescence markers and characteristic morphological changes in senescent cells, including enlargement, flattening, and multinucleation, were observed in cancer cells after 5 days of γ-irradiation. Then, NIR-PIT targeting EGFR was performed on these senescent cancer cells. The NIR-PIT induced morphological changes, including bleb formation, swelling, and the inflow of extracellular fluid, and induced a significant decrease in cellular viability. These results suggested that NIR-PIT may induce cytotoxicity using the same mechanism in senescent cancer cells. In addition, similar morphological changes were also induced in radiation-induced senescent 3T3-HER2 fibroblasts by NIR-PIT targeting human epidermal growth factor receptor 2.

CONCLUSION

NIR-PIT eliminates both senescent cancer and stromal cells in vitro suggesting it may be a novel strategy for tumor treatment.

Dendritic Polymer-Based Nanomedicines Remodel the Tumor Stroma: Improve Drug Penetration and Enhance Antitumor Immune Response

The dense extracellular matrix (ECM) in solid tumors, contributed by cancer-associated fibroblasts (CAFs), hinders penetration of drugs and diminishes their therapeutic outcomes. A sequential treatment strategy of remodeling the ECM via a CAF modifier (dasatinib, DAS) is proposed to promote penetration of an immunogenic cell death (ICD) inducer (epirubicin, Epi) via apoptotic vesicles, ultimately enhancing the treatment efficacy against breast cancer. Dendritic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA)-based nanomedicines (poly[OEGMA-Dendron(G2)-Gly-Phe-Leu-Gly-DAS] (P-DAS) and poly[OEGMA-Dendron(G2)-hydrazone-Epi] (P-Epi)) are developed for sequential delivery of DAS and Epi, respectively. P-DAS reprograms CAFs to reduce collagen by downregulating collagen anabolism and energy metabolism, thereby reducing the ECM deposition. The regulated ECM can enhance tumor penetration of P-Epi to strengthen its ICD effect, leading to an amplified antitumor immune response. In breast cancer-bearing mice, this approach alleviates the ECM barrier, resulting in reduced tumor burden and increased cytotoxic T lymphocyte infiltration, and more encouragingly, synergizes effectively with anti-programmed cell death 1 (PD-1) therapy, significantly inhibiting tumor growth and preventing lung metastasis. Furthermore, systemic toxicity is barely detectable after sequential treatment with P-DAS and P-Epi. This approach opens a new avenue for treating desmoplastic tumors by metabolically targeting CAFs to overcome the ECM barrier.

Integrated pan-cancer analysis reveals the immunological and prognostic potential of RBFOX2 in human tumors

Background

The role of RNA-binding fox one homolog 2 (RBFOX2) in the progression of multiple tumors is increasingly supported by evidence. However, the unclearness pertaining to the expression of RBFOX2, its prognostic potential, and its correlation with the tumor microenvironment (TME) in pan-cancer persists. This study aims to comprehensively investigate the immunological prognostic value of RBFOX2.

Methods

The Cancer Genome Atlas Gene Expression Omnibus Genotype-Tissue Expression (GTEx), TIMER2.0, Kaplan-Meier (K-M) Plotter, University of Alabama at Birmingham Cancer data analysis Portal (UALCAN), cbioportal, and Gene Expression Profiling Interactive Analysis 2 (GEPIA2) were utilized for a systematic analysis of RBFOX2. This analysis included studying its expression, prognostic value, DNA methylation, enrichment analysis, immune infiltration cells, and immune-related genes. Additionally, qRT-PCR, CCK-8, colony formation, transwell assays, and immunohistochemistry were employed to analyze the expression and biological function of RBFOX2 in liver cancer.

Results

Variations in RBFOX2 expression have been observed across diverse tumors and have been identified as indicators of unfavorable prognosis. It is closely linked to immune infiltration cells, immune checkpoints, chemokines, and chemokine receptors in the TME. Higher levels of RBFOX2 have been significantly associated with low response and poor prognosis in patients with non-small cell lung cancer (NSCLC) and melanoma who receive immunotherapy. Furthermore, the DNA methylation of RBFOX2 varies across different types of cancer and has shown better prognosis in patients with BLCA, BRCA, CESC, COAD, DLBC, HNSC, LAML, LGG, LUAD, PAAD, SKCM and THYM. Interestingly, RBFOX2 expression was found to be lower in hepatocellular carcinoma (HCC) patients' tumor tissues compared to their paired adjacent tissues. In vitro studies have shown that knockdown of RBFOX2 significantly promotes the growth and metastasis of liver cancer cells.

Conclusion

This study investigates the correlation between DNA methylation, prognostic value, and immune cell infiltration with the expression of RBFOX2 in pan-cancer and indicates its potential role to inhibit metastasis of liver cancer.

Exploring the multifaceted role of direct interaction between cancer cells and fibroblasts in cancer progression

The interaction between the tumor microenvironment (TME) and the cancer cells is a complex and mutually beneficial system that leads to rapid cancer cells proliferation, metastasis, and resistance to therapy. It is now recognized that cancer cells are not isolated, and tumor progression is governed among others, by many components of the TME. The reciprocal cross-talk between cancer cells and their microenvironment can be indirect through the secretion of extracellular matrix (ECM) proteins and paracrine signaling through exosomes, cytokines, and growth factors, or direct by cell-to-cell contact mediated by cell surface receptors and adhesion molecules. Among TME components, cancer-associated fibroblasts (CAFs) are of unique interest. As one of the most abundant components of the TME, CAFs play key roles in the reorganization of the extracellular matrix, facilitating metastasis and chemotherapy evasion. Both direct and indirect roles have been described for CAFs in modulating tumor progression. In this review, we focus on recent advances in understanding the role of direct contact between cancer cells and cancer-associated fibroblasts (CAFs) in driving tumor development and metastasis. We also summarize recent findings on the role of direct contact between cancer cells and CAFs in chemotherapy resistance.

Hydrogen Therapy Reverses Cancer-Associated Fibroblasts Phenotypes and Remodels Stromal Microenvironment to Stimulate Systematic Anti-Tumor Immunity

Tumor microenvironment (TME) plays an important role in the tumor progression. Among TME components, cancer-associated fibroblasts (CAFs) show multiple tumor-promoting effects and can induce tumor immune evasion and drug-resistance. Regulating CAFs can be a potential strategy to augment systemic anti-tumor immunity. Here, the study observes that hydrogen treatment can alleviate intracellular reactive oxygen species of CAFs and reshape CAFs' tumor-promoting and immune-suppressive phenotypes. Accordingly, a controllable and TME-responsive hydrogen therapy based on a CaCO3 nanoparticles-coated magnesium system (Mg-CaCO3) is developed. The hydrogen therapy by Mg-CaCO3 can not only directly kill tumor cells, but also inhibit pro-tumor and immune suppressive factors in CAFs, and thus augment immune activities of CD4+ T cells. As implanted in situ, Mg-CaCO3 can significantly suppress tumor growth, turn the "cold" primary tumor into "hot", and stimulate systematic anti-tumor immunity, which is confirmed by the bilateral tumor transplantation models of "cold tumor" (4T1 cells) and "hot tumor" (MC38 cells). This hydrogen therapy system reverses immune suppressive phenotypes of CAFs, thus providing a systematic anti-tumor immune stimulating strategy by remodeling tumor stromal microenvironment.

Cancer-associated fibroblasts promote enzalutamide resistance and PD-L1 expression in prostate cancer through CCL5-CCR5 paracrine axis

Cancer-associated fibroblasts (CAFs) have been shown to play a key role in prostate cancer treatment resistance, but the role of CAFs in the initial course of enzalutamide therapy for prostate cancer remains unclear. Our research revealed that CAFs secrete CCL5, which promotes the upregulation of androgen receptor (AR) expression in prostate cancer cells, leading to resistance to enzalutamide therapy. Furthermore, CCL5 also enhances the expression of tumor programmed death-ligand 1 (PD-L1), resulting in immune escape. Mechanistically, CCL5 binds to the receptor CCR5 on prostate cancer cells and activates the AKT signaling pathway, leading to the upregulation of AR and PD-L1. The CCR5 antagonist maraviroc to inhibit the CAFs mediated CCL5 signaling pathway can effectively reduce the expression of AR and PD-L1, and improve the efficacy of enzalutamide. This study highlights a promising therapeutic approach targeting the CCL5-CCR5 signaling pathway to improve the effectiveness of enzalutamide.

Mesothelioma-Associated Fibroblasts Modulate the Response of Mesothelioma Patient-Derived Organoids to Chemotherapy via Interleukin-6

Malignant pleural mesothelioma (MPM) remains an incurable disease. This is partly due to the lack of experimental models that fully recapitulate the complexity and heterogeneity of MPM, a major challenge for therapeutic management of the disease. In addition, the contribution of the MPM microenvironment is relevant for the adaptive response to therapy. We established mesothelioma patient-derived organoid (mPDO) cultures from MPM pleural effusions and tested their response to pemetrexed and cisplatin. We aimed to evaluate the contribution of mesothelioma-associated fibroblasts (MAFs) to the response to pemetrexed and cisplatin (P+C). Organoid cultures were obtained from eight MPM patients using specific growth media and conditions to expand pleural effusion-derived cells. Flow cytometry was used to verify the similarity of the organoid cultures to the original samples. MAFs were isolated and co-cultured with mPDOs, and the addition of MAFs reduced the sensitivity of mPDOs to P+C. Organoid formation and expression of cancer stem cell markers such as ABCG2, NANOG, and CD44 were altered by conditioned media from treated MAFs. We identified IL-6 as the major contributor to the attenuated response to chemotherapy. IL-6 secretion by MAFs is correlated with increased resistance of mPDOs to pemetrexed and cisplatin.

Angiogenesis Still Plays a Crucial Role in Human Melanoma Progression

Angiogenesis plays a pivotal role in tumor progression, particularly in melanoma, the deadliest form of skin cancer. This review synthesizes current knowledge on the intricate interplay between angiogenesis and tumor microenvironment (TME) in melanoma progression. Pro-angiogenic factors, including VEGF, PlGF, FGF-2, IL-8, Ang, TGF-β, PDGF, integrins, MMPs, and PAF, modulate angiogenesis and contribute to melanoma metastasis. Additionally, cells within the TME, such as cancer-associated fibroblasts, mast cells, and melanoma-associated macrophages, influence tumor angiogenesis and progression. Anti-angiogenic therapies, while showing promise, face challenges such as drug resistance and tumor-induced activation of alternative angiogenic pathways. Rational combinations of anti-angiogenic agents and immunotherapies are being explored to overcome resistance. Biomarker identification for treatment response remains crucial for personalized therapies. This review highlights the complexity of angiogenesis in melanoma and underscores the need for innovative therapeutic approaches tailored to the dynamic TME.

Anoikis patterns via machine learning strategy and experimental verification exhibit distinct prognostic and immune landscapes in melanoma

BACKGROUND

Anoikis is a cell death programmed to eliminate dysfunctional or damaged cells induced by detachment from the extracellular matrix. Utilizing an anoikis-based risk stratification is anticipated to understand melanoma's prognostic and immune landscapes comprehensively.

METHODS

Differential expression genes (DEGs) were analyzed between melanoma and normal skin tissues in The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression data sets. Next, least absolute shrinkage and selection operator, support vector machine-recursive feature elimination algorithm, and univariate and multivariate Cox analyses on the 308 DEGs were performed to build the prognostic signature in the TCGA-melanoma data set. Finally, the signature was validated in GSE65904 and GSE22155 data sets. NOTCH3, PIK3R2, and SOD2 were validated in our clinical samples by immunohistochemistry.

RESULTS

The prognostic model for melanoma patients was developed utilizing ten hub anoikis-related genes. The overall survival (OS) of patients in the high-risk subgroup, which was classified by the optimal cutoff value, was remarkably shorter in the TCGA-melanoma, GSE65904, and GSE22155 data sets. Low-risk patients exhibited low immune cell infiltration and high expression of immunophenoscores and immune checkpoints. They also demonstrated increased sensitivity to various drugs, including dasatinib and dabrafenib. NOTCH3, PIK3R2, and SOD2 were notably associated with OS by univariate Cox analysis in the GSE65904 data set. The clinical melanoma samples showed remarkably higher protein expressions of NOTCH3 (P = 0.003) and PIK3R2 (P = 0.009) than the para-melanoma samples, while the SOD2 protein expression remained unchanged.

CONCLUSIONS

In this study, we successfully established a prognostic anoikis-connected signature using machine learning. This model may aid in evaluating patient prognosis, clinical characteristics, and immune treatment modalities for melanoma.

Macrophage-fibroblast JAK/STAT dependent crosstalk promotes liver metastatic outgrowth in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic disease for which better therapies are urgently needed. Fibroblasts and macrophages are heterogeneous cell populations able to enhance metastasis, but the role of a macrophage-fibroblast crosstalk in regulating their pro-metastatic functions remains poorly understood. Here we deconvolve how macrophages regulate metastasis-associated fibroblast (MAF) heterogeneity in the liver. We identify three functionally distinct MAF populations, among which the generation of pro-metastatic and immunoregulatory myofibroblastic-MAFs (myMAFs) critically depends on macrophages. Mechanistically, myMAFs are induced through a STAT3-dependent mechanism driven by macrophage-derived progranulin and cancer cell-secreted leukaemia inhibitory factor (LIF). In a reciprocal manner, myMAF secreted osteopontin promotes an immunosuppressive macrophage phenotype resulting in the inhibition of cytotoxic T cell functions. Pharmacological blockade of STAT3 or myMAF-specific genetic depletion of STAT3 restores an anti-tumour immune response and reduces metastases. Our findings provide molecular insights into the complex macrophage-fibroblast interactions in tumours and reveal potential targets to inhibit PDAC liver metastasis.

Biological Roles and Clinical Applications of Exosomes in Breast Cancer: A Brief Review

Breast cancer (BC) is a global health risk for women and has a high prevalence rate. The drug resistance, recurrence, and metastasis of BC affect patient prognosis, thus posing a challenge to scientists. Exosomes are extracellular vesicles (EVs) that originate from various cells; they have a double-layered lipid membrane structure and contain rich biological information. They mediate intercellular communication and have pivotal roles in tumor development, progression, and metastasis and drug resistance. Exosomes are important cell communication mediators in the tumor microenvironment (TME). Exosomes are utilized as diagnostic and prognostic biomarkers for estimating the treatment efficacy of BC and have the potential to function as tools to enable the targeted delivery of antitumor drugs. This review introduces recent progress in research on how exosomes influence tumor development and the TME. We also present the research progress on the application of exosomes as prognostic and diagnostic biomarkers and drug delivery tools.

Miro-mediated mitochondrial transport: A new dimension for disease-related abnormal cell metabolism?

Mitochondria are versatile and highly dynamic organelles found in eukaryotic cells that play important roles in a variety of cellular processes. The importance of mitochondrial transport in cell metabolism, including variations in mitochondrial distribution within cells and intercellular transfer, has grown in recent years. Several studies have demonstrated that abnormal mitochondrial transport represents an early pathogenic alteration in a variety of illnesses, emphasizing its significance in disease development and progression. Mitochondrial Rho GTPase (Miro) is a protein found on the outer mitochondrial membrane that is required for cytoskeleton-dependent mitochondrial transport, mitochondrial dynamics (fusion and fission), and mitochondrial Ca2+ homeostasis. Miro, as a critical regulator of mitochondrial transport, has yet to be thoroughly investigated in illness. This review focuses on recent developments in recognizing Miro as a crucial molecule in controlling mitochondrial transport and investigates its roles in diverse illnesses. It also intends to shed light on the possibilities of targeting Miro as a therapeutic method for a variety of diseases.

Pan-cancer dissection of vasculogenic mimicry characteristic to provide potential therapeutic targets

Introduction

Vasculogenic mimicry (VM) represents a novel form of tumor angiogenesis that is associated with tumor invasiveness and drug resistance. However, the VM landscape across cancer types remains poorly understood. In this study, we elucidate the characterizations of VM across cancers based on multi-omics data and provide potential targeted therapeutic strategies.

Methods

Multi-omics data from The Cancer Genome Atlas was used to conduct comprehensive analyses of the characteristics of VM related genes (VRGs) across cancer types. Pan-cancer vasculogenic mimicry score was established to provide a depiction of the VM landscape across cancer types. The correlation between VM and cancer phenotypes was conducted to explore potential regulatory mechanisms of VM. We further systematically examined the relationship between VM and both tumor immunity and tumor microenvironment (TME). In addition, cell communication analysis based on single-cell transcriptome data was used to investigate the interactions between VM cells and TME. Finally, transcriptional and drug response data from the Genomics of Drug Sensitivity in Cancer database were utilized to identify potential therapeutic targets and drugs. The impact of VM on immunotherapy was also further clarified.

Results

Our study revealed that VRGs were dysregulated in tumor and regulated by multiple mechanisms. Then, VM level was found to be heterogeneous among different tumors and correlated with tumor invasiveness, metastatic potential, malignancy, and prognosis. VM was found to be strongly associated with epithelial-mesenchymal transition (EMT). Further analyses revealed cancer-associated fibroblasts can promote EMT and VM formation. Furthermore, the immune-suppressive state is associated with a microenvironment characterized by high levels of VM. VM score can be used as an indicator to predict the effect of immunotherapy. Finally, seven potential drugs targeting VM were identified.

Conclusion

In conclusion, we elucidate the characteristics and key regulatory mechanisms of VM across various cancer types, underscoring the pivotal role of CAFs in VM. VM was further found to be associated with the immunosuppressive TME. We also provide clues for the research of drugs targeting VM. Our study provides an initial overview and reference point for future research on VM, opening up new avenues for therapeutic intervention.

Fibroblasts in the Aged Pancreas Drive Pancreatic Cancer Progression

Pancreatic cancer is more prevalent in older individuals and often carries a poorer prognosis for them. The relationship between the microenvironment and pancreatic cancer is multifactorial, and age-related changes in nonmalignant cells in the tumor microenvironment may play a key role in promoting cancer aggressiveness. Because fibroblasts have profound impacts on pancreatic cancer progression, we investigated whether age-related changes in pancreatic fibroblasts influence cancer growth and metastasis. Proteomics analysis revealed that aged fibroblasts secrete different factors than young fibroblasts, including increased growth/differentiation factor 15 (GDF-15). Treating young mice with GDF-15 enhanced tumor growth, whereas aged GDF-15 knockout mice showed reduced tumor growth. GDF-15 activated AKT, rendering tumors sensitive to AKT inhibition in an aged but not young microenvironment. These data provide evidence for how aging alters pancreatic fibroblasts and promotes tumor progression, providing potential therapeutic targets and avenues for studying pancreatic cancer while accounting for the effects of aging.

SIGNIFICANCE

Aged pancreatic fibroblasts secrete GDF-15 and activate AKT signaling to promote pancreatic cancer growth, highlighting the critical role of aging-mediated changes in the pancreatic cancer microenvironment in driving tumor progression. See related commentary by Isaacson et al., p. 1185.

FAP is a prognostic marker, but not a viable therapeutic target for clinical translation in HNSCC

PURPOSE

PD-1 targeted immunotherapy has imparted a survival benefit to advanced head and neck squamous cell carcinoma (HNSCC), but less than 20% patients produce a durable response to this therapy. Here we aimed to investigate the potential biomarkers for predicting the clinical outcome and resistance to PD-1 targeted immunotherapy in HNSCC patients, and to examine the involvement of FAP+ cancer-associated fibroblasts (CAFs).

METHODS

Bioinformatics methods were applied to analyze multiple datasets and explore the role of PD-1 and FAP in HNSCC. Immunohistochemistry was used to detect the expression of FAP protein. Fap gene knockout mice (Fap-/-) and L929 cells with different levels of Fap overexpression (L929-Fap-Low/High) were established to demonstrate the role of FAP+ CAFs in tumor development and immune checkpoint blockade (ICB) resistance.

RESULTS

The expression level of PD-1 gene was positively correlated with better overall survival and therapeutic response to PD-1 blockade in HNSCC, but not all tumors with high expression of both PD-1 and PD-L1 were responsive. Moreover, FAP gene was overexpressed in pan-cancer tissues, and could serve as a prognostic biomarker for several cancers, including HNSCC. However, FAP protein was undetectable in mouse MTCQ1 tumors and barely expressed in human HNSCC tumors. Furthermore, FAP+ CAFs did not promote tumor growth or enhance the resistance to PD-1 inhibitor treatment.

CONCLUSION

Although FAP+ CAFs have attracted increasing attention for their role in cancer, the feasibility and efficacy of FAP-targeting therapies for HNSCC remain doubtful.

Embracing cancer complexity: Hallmarks of systemic disease

The last 50 years have witnessed extraordinary developments in understanding mechanisms of carcinogenesis, synthesized as the hallmarks of cancer. Despite this logical framework, our understanding of the molecular basis of systemic manifestations and the underlying causes of cancer-related death remains incomplete. Looking forward, elucidating how tumors interact with distant organs and how multifaceted environmental and physiological parameters impinge on tumors and their hosts will be crucial for advances in preventing and more effectively treating human cancers. In this perspective, we discuss complexities of cancer as a systemic disease, including tumor initiation and promotion, tumor micro- and immune macro-environments, aging, metabolism and obesity, cancer cachexia, circadian rhythms, nervous system interactions, tumor-related thrombosis, and the microbiome. Model systems incorporating human genetic variation will be essential to decipher the mechanistic basis of these phenomena and unravel gene-environment interactions, providing a modern synthesis of molecular oncology that is primed to prevent cancers and improve patient quality of life and cancer outcomes.

Metabolic targeting of cancer associated fibroblasts overcomes T-cell exclusion and chemoresistance in soft-tissue sarcomas

T cell-based immunotherapies have exhibited promising outcomes in tumor control; however, their efficacy is limited in immune-excluded tumors. Cancer-associated fibroblasts (CAFs) play a pivotal role in shaping the tumor microenvironment and modulating immune infiltration. Despite the identification of distinct CAF subtypes using single-cell RNA-sequencing (scRNA-seq), their functional impact on hindering T-cell infiltration remains unclear, particularly in soft-tissue sarcomas (STS) characterized by low response rates to T cell-based therapies. In this study, we characterize the STS microenvironment using murine models (in female mice) with distinct immune composition by scRNA-seq, and identify a subset of CAFs we termed glycolytic cancer-associated fibroblasts (glyCAF). GlyCAF rely on GLUT1-dependent expression of CXCL16 to impede cytotoxic T-cell infiltration into the tumor parenchyma. Targeting glycolysis decreases T-cell restrictive glyCAF accumulation at the tumor margin, thereby enhancing T-cell infiltration and augmenting the efficacy of chemotherapy. These findings highlight avenues for combinatorial therapeutic interventions in sarcomas and possibly other solid tumors. Further investigations and clinical trials are needed to validate these potential strategies and translate them into clinical practice.

Ginsenoside Rh2-Based Multifunctional Liposomes for Advanced Breast Cancer Therapy

Background

Most solid tumors are not diagnosed and treated until the advanced stage, in which tumors have shaped mature self-protective power, leading to off-target drugs and nanomedicines. In the present studies, we established a more realistic large tumor model to test the antitumor activity of a multifunctional ginsenoside Rh2-based liposome system (Rh2-lipo) on advanced breast cancer.

Methods

Both cholesterol and PEG were substituted by Rh2 to prepare the Rh2-lipo using ethanol-water system and characterized. The effects of Rh2-lipo on cell uptake, penetration of the tumor spheroid, cytotoxicity assay was investigated with 4T1 breast cancer cells and L929 fibroblast cells. The 4T1 orthotopic-bearing large tumor model was established to study the targeting effect of Rh2-lipo and inhibitory effect of paclitaxel loaded Rh2-lipo (PTX-Rh2-lipo) on advanced breast tumors.

Results

Rh2-lipo exhibit many advantages that address the limitations of current liposome formulations against large tumors, such as enhanced uptake in TAFs and tumor cells, high targeting and penetration capacity, cytotoxicity against TAFs, normalization of the vessel network, and depletion of stromal collagen. In in vivo study, PTX-Rh2-lipo effectively inhibiting the growth of advanced breast tumors and outperformed most reported PTX formulations, including Lipusu® and Abraxane®.

Conclusion

Rh2-lipo have improved drug delivery efficiency and antitumor efficacy in advanced breast cancer, which offers a novel promising platform for advanced tumor therapy.

Multi-omic profiling of follicular lymphoma reveals changes in tissue architecture and enhanced stromal remodeling in high-risk patients

Follicular lymphoma (FL) is a generally incurable malignancy that evolves from developmentally blocked germinal center (GC) B cells. To promote survival and immune escape, tumor B cells undergo significant genetic changes and extensively remodel the lymphoid microenvironment. Dynamic interactions between tumor B cells and the tumor microenvironment (TME) are hypothesized to contribute to the broad spectrum of clinical behaviors observed among FL patients. Despite the urgent need, existing clinical tools do not reliably predict disease behavior. Using a multi-modal strategy, we examined cell-intrinsic and -extrinsic factors governing progression and therapeutic outcomes in FL patients enrolled onto a prospective clinical trial. By leveraging the strengths of each platform, we identify several tumor-specific features and microenvironmental patterns enriched in individuals who experience early relapse, the most high-risk FL patients. These features include stromal desmoplasia and changes to the follicular growth pattern present 20 months before first progression and first relapse.

ITGA7 loss drives the differentiation of adipose-derived mesenchymal stem cells to cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) represent a major cellular component of the tumor (pre-)metastatic niche and play an essential role in omental dissemination of ovarian cancer. The omentum is rich in adipose, and adipose-derived mesenchymal stem cells (ADSCs) have been identified as a source of CAFs. However, the molecular events driving the phenotype shift of ADSCs remain largely unexplored. In this research, we focus on integrins, transmembrane receptors that have been widely involved in cellular plasticity. We found that integrin α7 (ITGA7) was the only member of the integrin family that positively correlated with both overall survival and progression-free survival in ovarian cancer through GEPIA2. The immunohistochemistry signal of ITGA7 was apparent in the tumor stroma, and a lower omental ITGA7 level was associated with metastasis. Primary ADSCs were isolated from the omentum of patients with ovarian cancer and identified by cellular morphology, biomarkers, and multilineage differentiation. The conditional medium of ovarian cancer cells induced ITGA7 expression decrease and phenotypic changes in ADSCs. Downregulation of ITGA7 in primary omental ADSCs led to decrease in stemness properties and emerge of characteristic morphology and biomarkers of CAFs. Moreover, the conditioned medium of ADSCs with ITGA7 depletion exhibited enhanced abilities to improve the migration and invasion of ovarian cancer cells in vitro. Overall, these findings indicate that loss of ITGA7 may induce the differentiation of ADSCs to CAFs that contribute to a tumor-supportive niche.

Integrative single-cell transcriptomic analyses reveal the cellular ontological and functional heterogeneities of primary and metastatic liver tumors

BACKGROUND

The global cellular landscape of the tumor microenvironment (TME) combining primary and metastatic liver tumors has not been comprehensively characterized.

METHODS

Based on the scRNA-seq and spatial transcriptomic data of non-tumor liver tissues (NTs), primary liver tumors (PTs) and metastatic liver tumors (MTs), we performed the tissue preference, trajectory reconstruction, transcription factor activity inference, cell-cell interaction and cellular deconvolution analyses to construct a comprehensive cellular landscape of liver tumors.

RESULTS

Our analyses depicted the heterogeneous cellular ecosystems in NTs, PTs and MTs. The activated memory B cells and effector T cells were shown to gradually shift to inhibitory B cells, regulatory or exhausted T cells in liver tumors, especially in MTs. Among them, we characterized a unique group of TCF7+ CD8+ memory T cells specifically enriched in MTs that could differentiate into exhausted T cells likely driven by the p38 MAPK signaling. With regard to myeloid cells, the liver-resident macrophages and inflammatory monocyte/macrophages were markedly replaced by tumor-associated macrophages (TAMs), with TREM2+ and UBE2C+ TAMs enriched in PTs, while SPP1+ and WDR45B+ TAMs in MTs. We further showed that the newly identified WDR45B+ TAMs exhibit an M2-like polarization and are associated with adverse prognosis in patients with liver metastases. Additionally, we addressed that endothelial cells display higher immune tolerance and angiogenesis capacity, and provided evidence for the source of the mesenchymal transformation of fibroblasts in tumors. Finally, the malignant hepatocytes and fibroblasts were prioritized as the pivotal cell populations in shaping the microenvironments of PTs and MTs, respectively. Notably, validation analyses by using spatial or bulk transcriptomic data in clinical cohorts concordantly emphasized the clinical significance of these findings.

CONCLUSIONS

This study defines the ontological and functional heterogeneities in cellular ecosystems of primary and metastatic liver tumors, providing a foundation for future investigation of the underlying cellular mechanisms.

The Fibroblast Landscape in Stomach Carcinogenesis

Numerous recent studies using single cell RNA sequencing and spatial transcriptomics have shown the vast cell heterogeneity, including epithelial, immune, and stromal cells, present in the normal human stomach and at different stages of gastric carcinogenesis. Fibroblasts within the metaplastic and dysplastic mucosal stroma represent key contributors to the carcinogenic microenvironment in the stomach. The heterogeneity of fibroblast populations is present in the normal stomach, but plasticity within these populations underlies their alterations in association with both metaplasia and dysplasia. In this review, we summarize and discuss efforts over the past several years to study the fibroblast components in human stomach from normal to metaplasia, dysplasia, and cancer. In the stomach, myofibroblast populations increase during late phase carcinogenesis and are a source of matrix proteins. PDGFRA-expressing telocyte-like cells are present in normal stomach and expand during metaplasia and dysplasia in close proximity with epithelial lineages, likely providing support for both normal and metaplastic progenitor niches. The alterations in fibroblast transcriptional signatures across the stomach carcinogenesis process indicate that fibroblast populations are likely as plastic as epithelial populations during the evolution of carcinogenesis.

Spatiotemporal transformable nano-assembly for on-demand drug delivery to enhance anti-tumor immunotherapy

Induction of tumor cell senescence has become a promising strategy for anti-tumor immunotherapy, but fibrotic matrix severely blocks senescence inducers penetration and immune cells infiltration. Herein, we designed a cancer-associated fibroblasts (CAFs) triggered structure-transformable nano-assembly (HSD-P@V), which can directionally deliver valsartan (Val, CAFs regulator) and doxorubicin (DOX, senescence inducer) to the specific targets. In detail, DOX is conjugated with hyaluronic acid (HA) via diselenide bonds (Se-Se) to form HSD micelles, while CAFs-sensitive peptide is grafted onto the HSD to form a hydrophilic polymer, which is coated on Val nanocrystals (VNs) surface for improving the stability and achieving responsive release. Once arriving at tumor microenvironment and touching CAFs, HSD-P@V disintegrates into VNs and HSD micelles due to sensitive peptide detachment. VNs can degrade the extracellular matrix, leading to the enhanced penetration of HSD. HSD targets tumor cells, releases DOX to induce senescence, and recruits effector immune cells. Furthermore, senescent cells are cleared by the recruited immune cells to finish the integrated anti-tumor therapy. In vitro and in vivo results show that the nano-assembly remarkably inhibits tumor growth as well as lung metastasis, and extends tumor-bearing mice survival. This work provides a promising paradigm of programmed delivering multi-site nanomedicine for cancer immunotherapy.

Single-cell RNA sequencing in melanoma: what have we learned so far?

Over the past decade, there have been remarkable improvements in the treatment and survival rates of melanoma patients. Treatment resistance remains a persistent challenge, however, and is partly attributable to intratumoural heterogeneity. Melanoma cells can transition through a series of phenotypic and transcriptional cell states that vary in invasiveness and treatment responsiveness. The diverse stromal and immune contexture of the tumour microenvironment also contributes to intratumoural heterogeneity and disparities in treatment response in melanoma patients. Recent advances in single-cell sequencing technologies have enabled a more detailed understanding of melanoma heterogeneity and the underlying transcriptional programs that regulate melanoma cell diversity and behaviour. In this review, we examine the concept of intratumoural heterogeneity and the challenges it poses to achieving long-lasting treatment responses. We focus on the significance of next generation single-cell sequencing in advancing our understanding of melanoma diversity and the unique insights gained from single-cell studies.

A gene signature of cancer-associated fibroblasts predicts prognosis and treatment response in bladder cancer

OBJECTIVE

Due to the pivotal role cancer-associated fibroblasts (CAFs) play in tumor progression, our study aimed to develop a signature of CAFs-related gene (CRG) to predict the survival outcomes and treatment response of bladder cancer (BLCA).

METHODS

The transcriptome data and relevant clinical information about BLCA were collected from publicly available databases, including The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Weighted gene co-expression network analysis was utilized to uncover CAFs-associated hub genes, and subsequently, a risk model for survival prognosis was constructed using LASSO-Cox regression. The immune microenvironment, immune infiltration, immunotherapy response, and drug sensitivity were explored using ESTIMATE, CIBERSORT, TIDE, and oncoPredict algorithms. To verify the expression of the CRGs, additional analyses were performed using online databases (HPA, CCLE, TIMER, cBioPortal, and TISCH).

RESULTS

Our study developed a CRG signature and constructed a prognostic model. Significant differences in overall survival were observed between the two risk stratifications. The risk score increased with the infiltration of CAFs and tumor staging progression, while closely correlating with immune checkpoint expression and infiltration of CD8 T cells, follicular helper T cells, regulatory T cells, activated dendritic cells, M0 macrophages, M2 macrophages, and resting mast cells. Furthermore, a higher proportion of patients in the low-risk stratification exhibited responsiveness to immunotherapy, and significant variances in sensitivity to multiple chemotherapy medications were observed between the two risk stratifications.

CONCLUSION

The construction of the risk model based on the CRG signature offers new avenues for the prognosis evaluation and development of personalized treatment strategies for BLCA.

Imaging Molecular Targets and Metabolic Pathways in Breast Cancer for Improved Clinical Management: Current Practice and Future Perspectives

Breast cancer is the most frequently diagnosed cancer and leading cause of cancer-related deaths worldwide. Timely decision-making that enables implementation of the most appropriate therapy or therapies is essential for achieving the best clinical outcomes in breast cancer. While clinicopathologic characteristics and immunohistochemistry have traditionally been used in decision-making, these clinical and laboratory parameters may be difficult to ascertain or be equivocal due to tumor heterogeneity. Tumor heterogeneity is described as a phenomenon characterized by spatial or temporal phenotypic variations in tumor characteristics. Spatial variations occur within tumor lesions or between lesions at a single time point while temporal variations are seen as tumor lesions evolve with time. Due to limitations associated with immunohistochemistry (which requires invasive biopsies), whole-body molecular imaging tools such as standard-of-care [18F]FDG and [18F]FES PET/CT are indispensable in addressing this conundrum. Despite their proven utility, these standard-of-care imaging methods are often unable to image a myriad of other molecular pathways associated with breast cancer. This has stimulated interest in the development of novel radiopharmaceuticals targeting other molecular pathways and processes. In this review, we discuss validated and potential roles of these standard-of-care and novel molecular approaches. These approaches' relationships with patient clinicopathologic and immunohistochemical characteristics as well as their influence on patient management will be discussed in greater detail. This paper will also introduce and discuss the potential utility of novel PARP inhibitor-based radiopharmaceuticals as non-invasive biomarkers of PARP expression/upregulation.

Metastasis and cancer associated fibroblasts: taking it up a NOTCH

Metastasis is the least understood aspect of cancer biology. 90% of cancer related deaths occur due extensive metastatic burden in patients. Apart from metastasizing cancer cells, the pro-tumorigenic and pro-metastatic role of the tumor stroma plays a crucial part in this complex process often leading to disease relapse and therapy resistance. Cellular signaling processes play a crucial role in the process of tumorigenesis and metastasis when aberrantly turned on, not just in the cancer cells, but also in the cells of the tumor microenvironment (TME). One of the most conserved pathways includes the Notch signaling pathway that plays a crucial role in the development and progression of many cancers. In addition to its well documented role in cancer cells, recent evidence suggests crucial involvement of Notch signaling in the stroma as well. This review aims to highlight the current findings focusing on the oncogenic role of notch signaling in cancer cells and the TME, with a specific focus on cancer associated fibroblasts (CAFs), which constitute a major part of the tumor stroma and are important for tumor progression. Recent efforts have focused on the development of anti-cancer and anti-metastatic therapies targeting TME. Understanding the importance of Notch signaling in the TME would help identify important drivers for stromal reprogramming, metastasis and importantly, drive future research in the effort to develop TME-targeted therapies utilizing Notch.

Dissecting tumor microenvironment heterogeneity in syngeneic mouse models: insights on cancer-associated fibroblast phenotypes shaped by infiltrating T cells

Murine syngeneic tumor models have been used extensively for cancer research for several decades and have been instrumental in driving the discovery and development of cancer immunotherapies. These tumor models are very simplistic cancer models, but recent reports have, however, indicated that the different inoculated cancer cell lines can lead to the formation of unique tumor microenvironments (TMEs). To gain more knowledge from studies based on syngeneic tumor models, it is essential to obtain an in-depth understanding of the cellular and molecular composition of the TME in the different models. Additionally, other parameters that are important for cancer progression, such as collagen content and mechanical tissue stiffness across syngeneic tumor models have not previously been reported. Here, we compare the TME of tumors derived from six common syngeneic tumor models. Using flow cytometry and transcriptomic analyses, we show that strikingly unique TMEs are formed by the different cancer cell lines. The differences are reflected as changes in abundance and phenotype of myeloid, lymphoid, and stromal cells in the tumors. Gene expression analyses support the different cellular composition of the TMEs and indicate that distinct immunosuppressive mechanisms are employed depending on the tumor model. Cancer-associated fibroblasts (CAFs) also acquire very different phenotypes across the tumor models. These differences include differential expression of genes encoding extracellular matrix (ECM) proteins, matrix metalloproteinases (MMPs), and immunosuppressive factors. The gene expression profiles suggest that CAFs can contribute to the formation of an immunosuppressive TME, and flow cytometry analyses show increased PD-L1 expression by CAFs in the immunogenic tumor models, MC38 and CT26. Comparison with CAF subsets identified in other studies shows that CAFs are skewed towards specific subsets depending on the model. In athymic mice lacking tumor-infiltrating cytotoxic T cells, CAFs express lower levels of PD-L1 and lower levels of fibroblast activation markers. Our data underscores that CAFs can be involved in the formation of an immunosuppressive TME.

MIR222HG/LIN28B/ATG5 Axis Drives M2 Macrophage Polarization and Proliferation of Hepatocellular Carcinoma Cells

Long non-coding RNAs (lncRNAs) are involved in the pathogenesis of hepatocellular carcinoma (HCC). This study aimed to investigate the potential of MIR222HG in HCC. HCC cells were co-cultured with U937 cells. Gene expression was determined using reverse transcription-quantitative (RT-q) PCR and western blot. Functional analysis was performed using Cell Counting Kit 8 (CCK-8), colony formation, and flow cytometry assays. We found that MIR222HG was overexpressed in HCC patients as well as HepG2 and Huh7 cells. MIR222HG-mediated upregulation of autophagy related 5 (ATG5) promoted tumor cell autophagy and the activation of M2-like tumor-associated macrophages (TAM2). Moreover, MIR222HG-mediated the activation of TAM2 drove the proliferation of HCC cells. Additionally, MIR222HG increased the mRNA expression as well as promoted the mRNA stability of ATG5 via binding to lin-28 homolog B (LIN28B). In conclusion, MIR222HG-mediated autophagy and the activation of TAM2 promote the aggressiveness of HCC cells via regulating LIN28B/ATG5 signaling.

Addressing Genetic Tumor Heterogeneity, Post-Therapy Metastatic Spread, Cancer Repopulation, and Development of Acquired Tumor Cell Resistance

The concept of post-therapy metastatic spread, cancer repopulation and acquired tumor cell resistance (M-CRAC) rationalizes tumor progression because of tumor cell heterogeneity arising from post-therapy genetic damage and subsequent tissue repair mechanisms. Therapeutic strategies designed to specifically address M-CRAC involve tissue editing approaches, such as low-dose metronomic chemotherapy and the use of transcriptional modulators with or without targeted therapies. Notably, tumor tissue editing holds the potential to treat patients, who are refractory to or relapsing (r/r) after conventional chemotherapy, which is usually based on administering a maximum tolerable dose of a cytostatic drugs. Clinical trials enrolling patients with r/r malignancies, e.g., non-small cell lung cancer, Hodgkin's lymphoma, Langerhans cell histiocytosis and acute myelocytic leukemia, indicate that tissue editing approaches could yield tangible clinical benefit. In contrast to conventional chemotherapy or state-of-the-art precision medicine, tissue editing employs a multi-pronged approach targeting important drivers of M-CRAC across various tumor entities, thereby, simultaneously engaging tumor cell differentiation, immunomodulation, and inflammation control. In this review, we highlight the M-CRAC concept as a major factor in resistance to conventional cancer therapies and discusses tissue editing as a potential treatment.

Large-scale analysis of cell-cell communication reveals angiogenin-dependent tumor progression in clear cell renal cell carcinoma

Cellular crosstalk in the tumor microenvironment (TME) is still largely uncharacterized, while it plays an essential role in shaping immunosuppression or anti-tumor response. Large-scale analyses are needed to better decipher cell-cell communication in cancer. In this work, we used original and publicly available single-cell RNA sequencing (scRNAseq) data to characterize in-depth the communication networks in human clear cell renal cell carcinoma (ccRCC). We identified 50 putative communication channels specifically used by cancer cells to interact with other cells, including two novel angiogenin-mediated interactions. Expression of angiogenin and its receptors was validated at the protein level in primary ccRCC. Mechanistically, angiogenin enhanced ccRCC cell line proliferation and down-regulated secretion of IL-6, IL-8, and MCP-1 proinflammatory molecules. This study provides novel biological insights into molecular mechanisms of ccRCC, and suggests angiogenin and its receptors as potential therapeutic targets in clear cell renal cancer.

Mutual regulation of TGFβ-induced oncogenic EMT, cell cycle progression and the DDR

TGFβ signaling and the DNA damage response (DDR) are two cellular toolboxes with a strong impact on cancer biology. While TGFβ as a pleiotropic cytokine affects essentially all hallmarks of cancer, the multifunctional DDR mostly orchestrates cell cycle progression, DNA repair, chromatin remodeling and cell death. One oncogenic effect of TGFβ is the partial activation of epithelial-to-mesenchymal transition (EMT), conferring invasiveness, cellular plasticity and resistance to various noxae. Several reports show that both individual networks as well as their interface affect chemo-/radiotherapies. However, the underlying mechanisms remain poorly resolved. EMT often correlates with TGFβ-induced slowing of proliferation, yet numerous studies demonstrate that particularly the co-activated EMT transcription factors counteract anti-proliferative signaling in a partially non-redundant manner. Collectively, evidence piled up over decades underscore a multifaceted, reciprocal inter-connection of TGFβ signaling / EMT with the DDR / cell cycle progression, which we will discuss here. Altogether, we conclude that full cell cycle arrest is barely compatible with the propagation of oncogenic EMT traits and further propose that 'EMT-linked DDR plasticity' is a crucial, yet intricate facet of malignancy, decisively affecting metastasis formation and therapy resistance.

Combined inhibition of surface CD51 and γ-secretase-mediated CD51 cleavage improves therapeutic efficacy in experimental metastatic hepatocellular carcinoma

BACKGROUND & AIMS

Integrin αv (ITGAV, CD51) is regarded as a key component in multiple stages of tumor progression. However, the clinical failure of cilengitide, a specific inhibitor targeting surface CD51, suggests the importance of yet-unknown mechanisms by which CD51 promotes tumor progression.

METHODS

In this study, we used several hepatocellular carcinoma (HCC) cell lines and murine hepatoma cell lines. To investigate the role of CD51 on HCC progression, we used a 3D invasion assay and in vivo bioluminescence imaging. We used periostin-knockout transgenic mice to uncover the role of the tumor microenvironment on CD51 cleavage. Moreover, we used several clinically relevant HCC models, including patient-derived organoids and patient-derived xenografts, to evaluate the therapeutic efficacy of cilengitide in combination with the γ-secretase inhibitor LY3039478.

RESULTS

We found that CD51 could undergo transmembrane cleavage by γ-secretase to produce a functional intracellular domain (CD51-ICD). The cleaved CD51-ICD facilitated HCC invasion and metastasis by promoting the transcription of oxidative phosphorylation-related genes. Furthermore, we identified cancer-associated fibroblast-derived periostin as the major driver of CD51 cleavage. Lastly, we showed that cilengitide-based therapy led to a dramatic therapeutic effect when supplemented with LY3039478 in both patient-derived organoid and xenograft models.

CONCLUSIONS

In summary, we revealed previously unrecognized mechanisms by which CD51 is involved in HCC progression and uncovered the underlying cause of cilengitide treatment failure, as well as providing evidence supporting the translational prospects of combined CD51-targeted therapy in the clinic.

IMPACT AND IMPLICATIONS

Integrin αv (CD51) is a widely recognized pro-tumoral molecule that plays a crucial role in various stages of tumor progression, making it a promising therapeutic target. However, despite early promising results, cilengitide, a specific antagonist of CD51, failed in a phase III clinical trial. This prompted further investigation into the underlying mechanisms of CD51's effects. This study reveals that the γ-secretase complex directly cleaves CD51 to produce an intracellular domain (CD51-ICD), which functions as a pro-tumoral transcriptional regulator and can bypass the inhibitory effects of cilengitide by entering the nucleus. Furthermore, the localization of CD51 in the nucleus is significantly associated with the prognosis of patients with HCC. These findings provide a theoretical basis for re-evaluating cilengitide in clinical settings and highlight the importance of identifying a more precise patient subpopulation for future clinical trials targeting CD51.

Tracking the Routes of Cancer: The Microevolution of Cancer-Associated Fibroblasts

Cancers are heterogeneous, multicellular societies that constitute solid tumors which comprise the neoplastic progenies of the tumor-initiating cell and the progenies of "un-transformed" tumor-infiltrating cells [...].

Prognostic and immunological role of cancer-associated fibroblasts-derived exosomal protein in esophageal squamous cell carcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) are a crucial component of the tumor microenvironment (TME) and play significant roles in tumor initiation, progression, and immune evasion. Despite this, the specific exosomal proteins derived from CAFs and their functions in esophageal squamous cell carcinoma (ESCC) remain unknown. Therefore, this study aims to investigate the impact and prognostic significance of CAFs-derived exosomal proteins in ESCC.

MATERIALS AND METHODS

Exosomes obtained from CAFs and normal fibroblasts (NFs) were isolated using ultracentrifugation, and the protein expression profiles of the exosomes were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Tumor proliferation was assessed using CCK-8 and colony formation assays, while cell invasion and migration were evaluated using transwell assays. Lasso regression analysis was employed to establish a signature based on CAFs-derived exosomal proteins using the TCGA database. The immunological and prognostic roles of this signature were comprehensively investigated through survival analysis, gene set enrichment analysis (GSEA), immune analysis, immunotherapy response analysis, and drug sensitivity analysis. The GSE160269 dataset was utilized for single-cell transcriptome analysis to further elucidate the role of the signature in the TME. Additionally, cDNA microarray analysis was utilized to validate the prognostic value of the signature.

RESULTS

Our findings demonstrate that exosomes derived from CAFs significantly enhance the proliferation, invasion, and migration of esophageal cancer cells. We identified 842 differentially expressed exosomal proteins through LC-MS/MS analysis, and two key proteins were utilized to establish a risk signature. Survival analysis revealed a significantly worse prognosis in the high-risk group, with multivariate analysis indicating that the risk score serves as an independent prognostic factor. Moreover, we observed a significant correlation between the risk score and immune cell infiltration, immunotherapy response, and sensitivity to chemotherapeutic treatments in the study population. Lastly, single-cell transcriptome analysis further revealed the expression patterns of TNFRSF10B and ILF3 in different cell subpopulations.

CONCLUSION

In conclusion, our study has successfully established a robust prognostic signature based on CAFs-derived exosomal proteins, which can serve as a reliable biomarker for predicting prognosis and evaluating the immune microenvironment in ESCC.

Breaking the mold: Overcoming resistance to immune checkpoint inhibitors

Immune checkpoint blockade-based therapies are effective against a sorts of cancers. However, drug resistance is a problem that cannot be ignored. This review intends to elucidate the mechanisms underlying drug tolerance induced by PD-1/PD-L1 inhibitors, as well as to outline proposed mechanism-based combination therapies and small molecule drugs that target intrinsic immunity and immune checkpoints. According to the differences of patients and types of cancer, the optimization of individualized combination therapy will help to enhance PD-1/PD-L1-mediated immunoregulation, reduce chemotherapy resistance, and provide new ideas for chemotherapy-resistant cancer.