Single-cell transcriptome reveals cellular hierarchies and guides p-EMT-targeted trial in skull base chordoma

Multi-omics analysis unveils the role of inflammatory cancer-associated fibroblasts in chordoma progression

Cancer-associated fibroblasts (CAFs) constitute the primary cellular component of the stroma in chordomas, characterized by an abundance of mucinous stromal elements, potentially facilitating their initiation and progression; however, this inference has yet to be fully confirmed. In this study, single-cell RNA sequencing (scRNA-seq), spatial transcriptomics (ST), bulk RNA-seq, multiplexed quantitative immunofluorescence (QIF), and in vivo and in vitro experiments were performed to determine the heterogeneity, spatial distribution, and clinical significance of CAFs in chordoma. ScRNA-seq was performed on 87,693 single cells derived from seven tumor samples and four control nucleus pulposus samples. A distinct CAF cluster distinguished by the upregulated expression of inflammatory genes and enriched functionality in activating inflammation-associated cells was identified. Pseudotime trajectory and cell communication analyses suggested that this inflammatory CAF (iCAF) subset originated from normal fibroblasts and interacted extensively with tumors and various other cell types. By integrating the scRNA-seq results with ST, the presence of iCAF in chordoma tissue was further confirmed, indicating their positioning at a distance from the tumor cells. Bulk RNA-seq data analysis from 126 patients revealed a correlation between iCAF signature scores, chordoma invasiveness, and poor prognosis. QIF validation involving an additional 116 patients found that although iCAFs were not in close proximity to tumor cells compared with other CAF subsets, their density correlated with malignant tumor phenotypes and adverse outcomes. In vivo and in vitro experiments further confirmed that iCAFs accelerate the malignant progression of chordomas. These findings could provide insights into the development of novel therapeutic strategies. © 2024 The Pathological Society of Great Britain and Ireland.

Combinatorial therapies for epigenetic, immunotherapeutic, and genetic targeting of chordoma

PURPOSE

Chordoma, a rare malignancy of the axial skeleton and skull base, presents significant therapeutic challenges due to the high rates of tumor recurrence and resistance. While surgical resection and radiation therapy remain the gold standard of treatment, the lack of additional treatment options necessitates the exploration of novel therapies. Combinatorial therapies hold significant potential in shaping patient prognosis. By targeting the immunotherapeutic, epigenetic, and genetic landscapes of chordoma, these methods enable the more effective and personalized management of the diverse molecular mechanisms driving chordoma growth and resistance.

METHODS

To elucidate such potential, we conducted a literature review of all published articles on the usage of immunotherapeutic, epigenetic, and genetic approaches for chordoma treatment from 2014 to 2024.

RESULTS

Eighty-one papers were excluded based on our inclusion criteria. From the remaining thirty-nine publications, we found evidence supporting the efficacy of immune checkpoint inhibitors (ICIs), chimeric antigen receptor (CAR) T-cell therapies, and monoclonal antibodies; the roles of DNA methylation patterns, histone modification pathways, and miRNA regulation; and the contribution of cancer stem-like cells (CSCs) to chordoma progression.

CONCLUSION

Our findings underscore the importance of a multidirectional approach in chordoma treatment throughout the disease progression to reduce morbidity and improve patient outcomes despite the heterogeneity of chordoma.

Tumor-derived IL-6 promotes chordoma invasion by stimulating tumor-associated macrophages M2 polarization and TNFα secretion

AIMS

Chordoma is a rare and aggressive bone tumor with high-recurrence and lack of effective treatment methods. Tumor associated macrophages (TAMs) are abundant in tumor microenvironment (TME) and polarize toward M2 in chordoma. It has been observed that the high proportion of M2 cells is associated with chordoma rapid progression. However, the mechanism of TAMs polarization and promotion to tumor progression in chordoma is still unclear. The is an urgent need for further research.

MATERIALS AND METHODS

Flow cytometry and immunohistochemical staining was used to detect the degree of macrophages infiltration in chordoma. A co-culture model of chordoma cells and macrophages was established in vitro to investigate the effects of their interaction on cell function, cytokine secretion, and RNA transcriptome expression.

KEY FINDINGS

In this study, we found M2 macrophage was predominantly abundant immune cell population in chordoma, and its proportion was associated with the degree of bone destruction. We demonstrated that interleukin 6 (IL-6) derived from chordoma cells could induce TAMs polarization by activating STAT3 phosphorylation, and TAMs could enhance chordoma cells migration and invasion through TNFα/NF-κB pathway. The interaction of chordoma cells and TAMs could promote the bone destruction-related factor Cathepsin B (CTSB) and inhibitory immune checkpoints expression. We also confirmed blocking IL-6/STAT3 pathway could significantly attenuate the M2 polarization of TAMs and decrease the secretion of TNFα.

SIGNIFICANCE

This study illustrates the dynamics between chordoma cells and TAMs in promoting chordoma invasion and suggests that IL-6/STAT3 pathway is a potential therapeutic target to reduce TAM-induced chordoma invasion.

EGCG inhibits migration, invasion and epithelial-mesenchymal transition of renal cell carcinoma by activating TFEB-mediated autophagy

BACKGROUND

The incidence of renal cell carcinoma (RCC) is already in the top ten of all types of cancers, with more than 4 %. Epigallocatechin gallate (EGCG), a polyphenolic compound extracted from green tea, has been shown to be effective in the treatment of various tumors. However, limited studies have demonstrated the effect of EGCG on RCC and its underlying molecular mechanisms.

METHODS

After exposure to gradient concentration (0,5,10,20,40,60,80,100 μM) of EGCG, the cell viability of RCC cells was determined by MTT assay. The migration and invasion abilities of RCC cells were investigated by wound healing and transwell assays. The expression levels of proteins involved in the epithelial-mesenchymal transition (EMT) and autophagy were explored by Western blotting assays. The formation of autophagosome was detected by electron microscope and LC3 puncta assays. Nude mouse xenograft model was used as the model system in vivo.

RESULTS

In the present study, EGCG significantly inhibited the migration, invasion and EMT of RCC cells in a concentrated manner. Further exploration of its mechanism indicated that autophagy is involved in EGCG-mediated metastasis inhibition and EMT inhibition of RCC cells. In addition, EGCG could significantly up-regulate the transcription factor EB (TFEB) and promotes its nuclear localization. The incorporation of TFEB into the nucleus enhanced the transcriptional levels of molecules associated with autophagy. TFEB knockdown inhibited EGCG-mediated autophagy activation, metastasis and EMT inhibition in RCC cells.

CONCLUSIONS

In conclusion, these findings demonstrate for the first time that EGCG inhibits migration, invasion, and EMT of RCC by activating TFEB-mediated autophagy. Therefore, the combination of EGCG and TFFB activators or EMT inhibitors is expected to be a promising therapeutic strategy for RCC.

Single-cell and spatial omics unravel the spatiotemporal biology of tumour border invasion and haematogenous metastasis

Solid tumours exhibit a well-defined architecture, comprising a differentiated core and a dynamic border that interfaces with the surrounding tissue. This border, characterised by distinct cellular morphology and molecular composition, serves as a critical determinant of the tumour's invasive behaviour. Notably, the invasive border of the primary tumour represents the principal site for intravasation of metastatic cells. These cells, known as circulating tumour cells (CTCs), function as 'seeds' for distant dissemination and display remarkable heterogeneity. Advancements in spatial sequencing technology are progressively unveiling the spatial biological features of tumours. However, systematic investigations specifically targeting the characteristics of the tumour border remain scarce. In this comprehensive review, we illuminate key biological insights along the tumour body-border-haematogenous metastasis axis over the past five years. We delineate the distinctive landscape of tumour invasion boundaries and delve into the intricate heterogeneity and phenotype of CTCs, which orchestrate haematogenous metastasis. These insights have the potential to explain the basis of tumour invasion and distant metastasis, offering new perspectives for the development of more complex and precise clinical interventions and treatments.

Proteogenomic characterization of skull-base chordoma

Skull-base chordoma is a rare, aggressive bone cancer with a high recurrence rate. Despite advances in genomic studies, its molecular characteristics and effective therapies remain unknown. Here, we conduct integrative genomics, transcriptomics, proteomics, and phosphoproteomics analyses of 187 skull-base chordoma tumors. In our study, chromosome instability is identified as a prognostic predictor and potential therapeutic target. Multi-omics data reveals downstream effects of chromosome instability, with RPRD1B as a putative target for radiotherapy-resistant patients. Chromosome 1q gain, associated with chromosome instability and upregulated mitochondrial functions, lead to poorer clinical outcomes. Immune subtyping identify an immune cold subtype linked to chromosome 9p/10q loss and immune evasion. Proteomics-based classification reveals subtypes (P-II and P-III) with high chromosome instability and immune cold features, with P-II tumors showing increased invasiveness. These findings, confirmed in 17 paired samples, provide insights into the biology and treatment of skull-base chordoma.

Epithelial-mesenchymal plasticity in cancer: signaling pathways and therapeutic targets

Currently, cancer is still a leading cause of human death globally. Tumor deterioration comprises multiple events including metastasis, therapeutic resistance and immune evasion, all of which are tightly related to the phenotypic plasticity especially epithelial-mesenchymal plasticity (EMP). Tumor cells with EMP are manifest in three states as epithelial-mesenchymal transition (EMT), partial EMT, and mesenchymal-epithelial transition, which orchestrate the phenotypic switch and heterogeneity of tumor cells via transcriptional regulation and a series of signaling pathways, including transforming growth factor-β, Wnt/β-catenin, and Notch. However, due to the complicated nature of EMP, the diverse process of EMP is still not fully understood. In this review, we systematically conclude the biological background, regulating mechanisms of EMP as well as the role of EMP in therapy response. We also summarize a range of small molecule inhibitors, immune-related therapeutic approaches, and combination therapies that have been developed to target EMP for the outstanding role of EMP-driven tumor deterioration. Additionally, we explore the potential technique for EMP-based tumor mechanistic investigation and therapeutic research, which may burst vigorous prospects. Overall, we elucidate the multifaceted aspects of EMP in tumor progression and suggest a promising direction of cancer treatment based on targeting EMP.

Single-cell RNA-seq reveals the transcriptional program underlying tumor progression and metastasis in neuroblastoma

Neuroblastoma (NB) is one of the most common childhood malignancies. Sixty percent of patients present with widely disseminated clinical signs at diagnosis and exhibit poor outcomes. However, the molecular mechanisms triggering NB metastasis remain largely uncharacterized. In this study, we generated a transcriptomic atlas of 15 447 NB cells from eight NB samples, including paired samples of primary tumors and bone marrow metastases. We used time-resolved analysis to chart the evolutionary trajectory of NB cells from the primary tumor to the metastases in the same patient and identified a common 'starter' subpopulation that initiates tumor development and metastasis. The 'starter' population exhibited high expression levels of multiple cell cycle-related genes, indicating the important role of cell cycle upregulation in NB tumor progression. In addition, our evolutionary trajectory analysis demonstrated the involvement of partial epithelial-to-mesenchymal transition (p-EMT) along the metastatic route from the primary site to the bone marrow. Our study provides insights into the program driving NB metastasis and presents a signature of metastasis-initiating cells as an independent prognostic indicator and potential therapeutic target to inhibit the initiation of NB metastasis.

Complex immune microenvironment of chordoma: a road map for future treatment

BACKGROUND

Chordoma, a rare bone tumor, presents limited treatment options and patients typically exhibit poor survival outcomes. While immunotherapy has shown promising results in treating various tumors, research on the immune microenvironment of chordomas is still in its early stages. Therefore, understanding how the immune microenvironment of chordomas influences the outcomes of immunotherapy is crucial.

METHODS

We employed single-cell RNA sequencing (scRNA-seq), bulk RNA-seq, CellChat, gene set variation analysis, as well as calculation of immune features to further dissect the complex immune microenvironment of chordoma.

RESULTS

Previous research by van Oost et al argued that compared with other sarcomas, chordomas typically exhibit an immunologically "hot" microenvironment, a conclusion with which we concur based on their research findings. Additionally, the authors suggest that T cell-mediated immunotherapy is feasible for the majority of chordomas. However, we are inclined to categorize them as an immune-excluded phenotype according to the latest classification methods, rather than persisting with the concepts of "cold" and "hot". Unlike them, we explored immune infiltration scores (IS), T lymphocyte scoring (TLS), and human leucocyte antigen class I (HLA-I) using Bulk RNA-seq data from 126 chordoma patients and found that higher IS, TLS, and higher HLA-I expression were associated with poorer patient prognosis. Additionally, CellChat analysis of scRNA-seq results from six chordoma patients revealed no direct interaction between T cells and tumor cells.

CONCLUSIONS

These findings suggested that the efficacy of T cell-based immunotherapy may be limited or even ineffective for patients with chordoma.

Single-cell sequencing reveals VEGFR as a potential target for CAR-T cell therapy in chordoma

BACKGROUND

Chordomas are rare osseous neoplasms with a dismal prognosis when they recur. Here we identified cell surface proteins that could potentially serve as novel immunotherapeutic targets in patients with chordoma.

METHODS

Fourteen chordoma samples from patients attending Xuanwu Hospital Capital Medical University were subjected to single-cell RNA sequencing. Target molecules were identified on chordoma cells and cancer metastasis-related signalling pathways characterised. VEGFR-targeting CAR-T cells and VEGFR CAR-T cells with an additional TGF-β scFv were synthesised and their in vitro antitumor activities were evaluated, including in a primary chordoma organoid model.

RESULTS

Single-cell transcriptome sequencing identified the chordoma-specific antigen VEGFR and TGF-β as therapeutic targets. VRGFR CAR-T cells and VEGFR/TGF-β scFv CAR-T cells recognised antigen-positive cells and exhibited significant antitumor effects through CAR-T cell activation and cytokine secretion. Furthermore, VEGFR/TGF-β scFv CAR-T cells showed enhanced and sustained cytotoxicity of chordoma cell lines in vitro compared with VRGFR CAR-T cells.

CONCLUSIONS

This study provides a comprehensive single-cell landscape of human chordoma and highlights its heterogeneity and the role played by TGF-β in chordoma progression. Our findings substantiate the potential of VEGFR as a target for CAR-T cell therapies in chordoma which, together with modulated TGF-β signalling, may augment the efficacy of CAR-T cells.

Role of immunotherapy in treatment refractory chordomas: review of current evidence

Introduction

Chordomas are aggressive tumors that are thought to arise from remnants of the embryological notochord. They can arise along the ventromedial aspect of the sacrum, mobile spine, and clivus-with most cases occurring in the sacrum or skull base. Despite surgery and radiation, chordomas often progress and become refractory to further treatment. The high recurrence rate of chordomas has created an urgent need to develop new systemic treatment options. Recent case reports and clinical trials have highlighted the use of immunotherapy for refractory chordomas. In this review, we summarize the results of these studies and discuss the potential role of immunotherapy for chordomas.

Methods

The PUBMED database was queried for studies mentioning both "Chordoma" and "Immunotherapy." All case series and case reports that involved administration of an immunotherapy for chordoma were included. Additional studies that were found during literature review were added. ClinicalTrials.Gov was queried for studies mentioning both "Chordoma" and "Immunotherapy." The final cohort consisted of all clinical trials that utilized immunotherapy for chordomas of any location.

Results

Eight case reports and series detailing the use of immunotherapy for treatment refractory chordoma were identified. Most patients received immunotherapy targeting the PD-1/PD-L1 interaction, and two patients received therapy targeting this interaction along with the tyrosine kinase inhibitor pazopanib. One patient received a vaccine derived from autologous tumor cells, and one patient received a viral vector that downregulated the effect of TGF-beta. One clinical trial utilized a brachyury vaccine in conjunction with standard of care radiotherapy.

Conclusions

Immunotherapy for chordoma is a promising area of investigation with increasing, but small, numbers of case series and clinical trials. Despite challenges in patient accrual, future directions in chordoma immunotherapy may lie in vaccine-based therapies and immune checkpoint inhibitors. Understanding chordoma heterogeneity and microenvironment will likely elucidate important chordoma features that will inform future clinical trial design.

Unraveling molecular signatures in rare bone tumors and navigating the cancer pathway landscapes for targeted therapeutics

Rare cancers (RCs), which account for over 20% of cancer cases, face significant research and treatment challenges due to their limited prevalence. This results in suboptimal outcomes compared to more common malignancies. Rare bone tumors (RBTs) constitute 5-10% of rare cancer cases and pose unique diagnostic complexities. The therapeutic potential of anti-cancer drugs for RBTs remains largely unexplored. Identifying molecular alterations in cancer-related genes and their associated pathways is essential for precision medicine in RBTs. Small molecule inhibitors and monoclonal antibodies targeting specific RBT-associated proteins show promise. Ongoing clinical trials aim to define RBT biomarkers, subtypes, and optimal treatment contexts, including combination therapies and immunotherapeutic agents. This review addresses the challenges in diagnosing, treating, and studying RBTs, shedding light on the current state of RBT biomarkers, potential therapeutic targets, and promising inhibitors. Rare cancers demand attention and innovative solutions to improve clinical outcomes.

Integrated Molecular and Histological Insights for Targeted Therapies in Mesenchymal Sinonasal Tract Tumors

PURPOSE OF REVIEW

This review aims to provide a comprehensive overview of mesenchymal sinonasal tract tumors (STTs), a distinct subset of STTs. Despite their rarity, mesenchymal STTs represent a unique clinical challenge, characterized by their rarity, often slow progression, and frequently subtle or overlooked symptoms. The complex anatomy of the sinonasal area, which includes critical structures such as the orbit, brain, and cranial nerves, further complicates surgical treatment options. This underscores an urgent need for more advanced and specialized therapeutic approaches.

RECENT FINDINGS

Advancements in molecular diagnostics, particularly in next-generation sequencing, have significantly enhanced our understanding of STTs. Consequently, the World Health Organization has updated its tumor classification to better reflect the distinct histological and molecular profiles of these tumors, as well as to categorize mesenchymal STTs with greater accuracy. The growing understanding of the molecular characteristics of mesenchymal STTs opens new possibilities for targeted therapeutic interventions, marking a significant shift in treatment paradigms. This review article concentrates on mesenchymal STTs, specifically addressing sinonasal tract angiofibroma, sinonasal glomangiopericytoma, biphenotypic sinonasal sarcoma, and skull base chordoma. These entities are marked by unique histopathological and molecular features, which challenge conventional treatment approaches and simultaneously open avenues for novel targeted therapies. Our discussion is geared towards delineating the molecular underpinnings of mesenchymal STTs, with the objective of enhancing therapeutic strategies and addressing the existing shortcomings in the management of these intricate tumors.

Spatial Transcriptomic and Metabolomic Landscapes of Oral Submucous Fibrosis-Derived Oral Squamous Cell Carcinoma and its Tumor Microenvironment

In South and Southeast Asia, the habit of chewing betel nuts is prevalent, which leads to oral submucous fibrosis (OSF). OSF is a well-established precancerous lesion, and a portion of OSF cases eventually progress to oral squamous cell carcinoma (OSCC). However, the specific molecular mechanisms underlying the malignant transformation of OSCC from OSF are poorly understood. In this study, the leading-edge techniques of Spatial Transcriptomics (ST) and Spatial Metabolomics (SM) are integrated to obtain spatial location information of cancer cells, fibroblasts, and immune cells, as well as the transcriptomic and metabolomic landscapes in OSF-derived OSCC tissues. This work reveals for the first time that some OSF-derived OSCC cells undergo partial epithelial-mesenchymal transition (pEMT) within the in situ carcinoma (ISC) region, eventually acquiring fibroblast-like phenotypes and participating in collagen deposition. Complex interactions among epithelial cells, fibroblasts, and immune cells in the tumor microenvironment are demonstrated. Most importantly, significant metabolic reprogramming in OSF-derived OSCC, including abnormal polyamine metabolism, potentially playing a pivotal role in promoting tumorigenesis and immune evasion is discovered. The ST and SM data in this study shed new light on deciphering the mechanisms of OSF-derived OSCC. The work also offers invaluable clues for the prevention and treatment of OSCC.

Integrating single-cell and spatial transcriptomics reveals endoplasmic reticulum stress-related CAF subpopulations associated with chordoma progression

BACKGROUND

With cancer-associated fibroblasts (CAFs) as the main cell type, the rich myxoid stromal components in chordoma tissues may likely contribute to its development and progression.

METHODS

Single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, bulk RNA-seq, and multiplexed quantitative immunofluorescence (QIF) were used to dissect the heterogeneity, spatial distribution, and clinical implication of CAFs in chordoma.

RESULTS

We sequenced here 72 097 single cells from 3 primary and 3 recurrent tumor samples, as well as 3 nucleus pulposus samples as controls using scRNA-seq. We identified a unique cluster of CAF in recurrent tumors that highly expressed hypoxic genes and was functionally enriched in endoplasmic reticulum stress (ERS). Pseudotime trajectory and cell communication analyses showed that this ERS-CAF subpopulation originated from normal fibroblasts and widely interacted with tumoral and immune cells. Analyzing the bulk RNA-seq data from 126 patients, we found that the ERS-CAF signature score was associated with the invasion and poor prognosis of chordoma. By integrating the results of scRNA-seq with spatial transcriptomics, we demonstrated the existence of ERS-CAF in chordoma tissues and revealed that this CAF subtype displayed the most proximity to its surrounding tumor cells. In subsequent QIF validation involving 105 additional patients, we confirmed that ERS-CAF was abundant in the chordoma microenvironment and located close to tumor cells. Furthermore, both ERS-CAF density and its distance to tumor cells were correlated with tumor malignant phenotype and adverse patient outcomes.

CONCLUSIONS

These findings depict the CAF landscape for chordoma and may provide insights into the development of novel treatment approaches.

Multimodal profiling of chordoma immunity reveals distinct immune contextures

BACKGROUND

Chordomas are rare cancers from the axial skeleton which present a challenging clinical management with limited treatment options due to their anatomical location. In recent years, a few clinical trials demonstrated that chordomas can respond to immunotherapy. However, an in-depth portrayal of chordoma immunity and its association with clinical parameters is still lacking.

METHODS

We present a comprehensive characterization of immunological features of 76 chordomas through application of a multimodal approach. Transcriptomic profiling of 20 chordomas was performed to inform on the activity of immune-related genes through the immunologic constant of rejection (ICR) signature. Multidimensional immunophenotyping through imaging mass cytometry was applied to provide insights in the different immune contextures of 32 chordomas. T cell infiltration was further evaluated in all 76 patients by means of multispectral immunofluorescence and then associated with clinical parameters through univariate and multivariate Cox proportional hazard models as well as Kaplan-Meier estimates. Moreover, distinct expression patterns of human leukocyte antigen (HLA) class I were assessed by immunohistochemical staining in all 76 patients. Finally, clonal enrichment of the T cell receptor (TCR) was sought through profiling of the variable region of TCRB locus of 24 patients.

RESULTS

Chordomas generally presented an immune "hot" microenvironment in comparison to other sarcomas, as indicated by the ICR transcriptional signature. We identified two distinct groups of chordomas based on T cell infiltration which were independent from clinical parameters. The highly infiltrated group was further characterized by high dendritic cell infiltration and the presence of multicellular immune aggregates in tumors, whereas low T cell infiltration was associated with lower overall cell densities of immune and stromal cells. Interestingly, patients with higher T cell infiltration displayed a more pronounced clonal enrichment of the TCR repertoire compared with those with low T cell counts. Furthermore, we observed that the majority of chordomas maintained HLA class I expression.

CONCLUSION

Our findings shed light on the natural immunity against chordomas through the identification of distinct immune contextures. Understanding their immune landscape could guide the development and application of immunotherapies in a tailored manner, ultimately leading to an improved clinical outcome for patients with chordoma.

The role of tumor immune microenvironment in chordoma: promising immunotherapy strategies

Chordoma is a rare malignant bone tumor with limited therapeutic options, which is resistant to conventional chemotherapy and radiotherapy, and targeted therapy is also shown with little efficacy. The long-standing delay in researching its mechanisms of occurrence and development has resulted in the dilemma of no effective treatment targets and no available drugs in clinical practice. In recent years, the role of the tumor immune microenvironment in driving tumor growth has become a hot and challenging topic in the field of cancer research. Immunotherapy has shown promising results in the treatment of various tumors. However, the study of the immune microenvironment of chordoma is still in its infancy. In this review, we aim to present a comprehensive reveal of previous exploration on the chordoma immune microenvironment and propose promising immunotherapy strategies for chordoma based on these characteristics.

Heterogeneity and plasticity of epithelial-mesenchymal transition (EMT) in cancer metastasis: Focusing on partial EMT and regulatory mechanisms

Epithelial-mesenchymal transition (EMT) or mesenchymal-epithelial transition (MET) plays critical roles in cancer metastasis. Recent studies, especially those based on single-cell sequencing, have revealed that EMT is not a binary process, but a heterogeneous and dynamic disposition with intermediary or partial EMT states. Multiple double-negative feedback loops involved by EMT-related transcription factors (EMT-TFs) have been identified. These feedback loops between EMT drivers and MET drivers finely regulate the EMT transition state of the cell. In this review, the general characteristics, biomarkers and molecular mechanisms of different EMT transition states were summarized. We additionally discussed the direct and indirect roles of EMT transition state in tumour metastasis. More importantly, this article provides direct evidence that the heterogeneity of EMT is closely related to the poor prognosis in gastric cancer. Notably, a seesaw model was proposed to explain how tumour cells regulate themselves to remain in specific EMT transition states, including epithelial state, hybrid/intermediate state and mesenchymal state. Additionally, this article also provides a review of the current status, limitations and future perspectives of EMT signalling in clinical applications.

Single-cell RNA sequencing to identify cellular heterogeneity and targets in cardiovascular diseases: from bench to bedside

The mechanisms of cardiovascular diseases (CVDs) remain incompletely elucidated. Single-cell RNA sequencing (scRNA-seq) has enabled the profiling of single-cell transcriptomes at unprecedented resolution and throughput, which is critical for deciphering cardiovascular cellular heterogeneity and underlying disease mechanisms, thereby facilitating the development of therapeutic strategies. In this review, we summarize cellular heterogeneity in cardiovascular homeostasis and diseases as well as the discovery of potential disease targets based on scRNA-seq, and yield new insights into the promise of scRNA-seq technology in precision medicine and clinical application.

"In medio stat virtus": Insights into hybrid E/M phenotype attitudes

Epithelial-mesenchymal plasticity (EMP) refers to the ability of cells to dynamically interconvert between epithelial (E) and mesenchymal (M) phenotypes, thus generating an array of hybrid E/M intermediates with mixed E and M features. Recent findings have demonstrated how these hybrid E/M rather than fully M cells play key roles in most of physiological and pathological processes involving EMT. To this regard, the onset of hybrid E/M state coincides with the highest stemness gene expression and is involved in differentiation of either normal and cancer stem cells. Moreover, hybrid E/M cells are responsible for wound healing and create a favorable immunosuppressive environment for tissue regeneration. Nevertheless, hybrid state is responsible of metastatic process and of the increasing of survival, apoptosis and therapy resistance in cancer cells. The present review aims to describe the main features and the emerging concepts regulating EMP and the formation of E/M hybrid intermediates by describing differences and similarities between cancer and normal hybrid stem cells. In particular, the comprehension of hybrid E/M cells biology will surely advance our understanding of their features and how they could be exploited to improve tissue regeneration and repair.