Endothelial-to-mesenchymal transition in tumour progression and its potential roles in tumour therapy

Single cell transcriptomics reveals the cellular heterogeneity of keloids and the mechanism of their aggressiveness

Keloid is a dermatofibrotic disease known for its aggressive nature and characterized by pathological scarring, which often leads to disfigurement and frequent recurrences. Effective therapies for keloids are still limited, presumably due to the inadequate comprehension of their aggressive mechanisms. In our study, we examined the unique scenario where both keloid and non-aggressive pathological scar originate from the same patient, providing a rare opportunity to explore the aggressive mechanisms of keloids through single-cell RNA sequencing. We found that the dominant fibroblast subgroup in keloids is mechanoresponsive group, which showed enhanced mechanotransduction and migration. This mechanoresponsive fibroblast subgroup is likely to be the key cell population and confer aggressive growth of keloids. The results also indicate that the endothelial cells and keratinocytes in keloid involve in endothelial-mesenchymal and epithelial-mesenchymal transitions. This study demonstrated the mechanoresponsive fibroblasts and multiple cellular mesenchymal processes could pave the way for further investigations into the keloid aggressiveness.

Single-cell RNA sequencing reveals the landscape of the cellular ecosystem of primary hepatocellular carcinoma

Hepatocellular carcinoma (HCC) cells, along with multiple nonmalignant stromal cells, such as fibroblasts, endothelial cells and immune cells, comprise an intricate cellular ecosystem, undergo dynamic phenotypic changes and present complicated cellular interactions, thus synergistically facilitating HCC initiation and progression and leading to treatment resistance. Clarifying the heterogeneity, cell plasticity and complexity of the cellular ecosystem of HCC will be highly beneficial for understanding HCC development and identifying novel therapeutic targets. Single-cell RNA sequencing (scRNA-seq) refers to profiling the transcriptome at single-cell resolution, and the development of scRNA-seq technology and analysis algorithms has greatly promoted the analysis of cell composition, cell subpopulation heterogeneity, development trajectory and cell-to-cell interactions in cell populations. In this review, we systematically summarized and discussed scRNA-seq in treatment-naive primary HCC and revealed the global cell composition of HCC; the widespread molecular heterogeneity of HCC cells; the molecular subtypes of fibroblasts; the cell composition, functional states and development trajectory of immune cells; and the frequent interactions between different cell types to systematically draw the landscape of the cellular ecosystem of primary HCC.

Vascular mimicry and mosaic vessels in parathyroid tumours: a new diagnostic approach?

AIMS

Evaluation of 'alternative' vascularisation in human cancer is considered an important prognostic parameter; the 2022 WHO classification of parathyroid tumours despite progresses in clinical triaging of patients strongly emphasises new histopathological parameters to properly stratify these lesions. 'Alternative' and 'classic' vessels were here investigated for the first time in parathyroid tumours for their possible histopathological and clinical relevance during progression.

METHODS

Using a double CD31/PAS staining, microvessel density (MVD, 'classic' CD31+ vessels), mosaic vessel density (MoVD, 'alternative' CD31+/-vessels) and vessel mimicry density (VMD, 'alternative' CD31-/PAS+ vessels) were evaluated in 4 normal parathyroid glands (N), 50 Adenomas (A), 35 Atypical Tumours (AT) and 10 Carcinomas (K).

RESULTS

Compared with N, MVD significantly increased in A (p=0.012) and decreased in K (p=0.013) with vessel counts lower than in AT and A (p<0.001). MoVs and VMs, absent in normal tissue, were documented in non-benign parathyroid lesions (AT, K) (p<0.001), with MoVs and VMs most represented in AT and K, respectively (p<0.001), in peripheral growing areas. Vessel distribution was correlated to neoplastic progression (r=-0.541 MVD; r=+0.760 MoVD, r=+0.733 VMD), with MVD decrease in AT and K inversely related to MoVD and VMD increase (r=-0.503 and r=-0.456).

CONCLUSIONS

'Alternative' vessel identification in parathyroid tumours is crucial because it: (1) explains the paradox of non-angiogenic tumours, consisting in a new bloody non-endothelial vessel network and (2) helps pathologists to unmask worrisome lesions. Furthermore, detection of alternative vascular systems in human tumours might explain the limited success of antiangiogenic therapies and encourage new oncological studies.

Antitumor activity of anlotinib in malignant melanoma: modulation of angiogenesis and vasculogenic mimicry

Malignant melanoma presents a formidable challenge due to its aggressive metastatic behavior and limited response to current treatments. To address this, our study delves into the impact of anlotinib on angiogenesis and vasculogenic mimicry using malignant melanoma cells and human umbilical vein endothelial cells. Evaluating tubular structure formation, cell proliferation, migration, invasion, and key signaling molecules in angiogenesis, we demonstrated that anlotinib exerts a dose-dependent inhibition on tubular structures and effectively suppresses cell growth and invasion in both cell types. Furthermore, in a mouse xenograft model, anlotinib treatment resulted in reduced tumor growth and vascular density. Notably, the downregulation of VEGFR-2, FGFR-1, PDGFR-β, and PI3K underscored the multitargeted antitumor activity of anlotinib. Our findings emphasize the therapeutic potential of anlotinib in targeting angiogenesis and vasculogenic mimicry, contributing to the development of novel strategies for combating malignant melanoma.

Characterization of tumor endothelial cells (TEC) in gastric cancer and development of a TEC-based risk signature using single-cell RNA-seq and bulk RNA-seq data

BACKGROUND

Tumor endothelial cells (TECs) are essential participants in tumorigenesis. This study is focused on elucidating the TEC traits in gastric cancer (GC) and constructing a prognostic risk model to predict the clinical outcome of GC patients.

METHODS

Single-cell RNA sequencing (scRNA-seq) data were obtained from the GEO database. Using specific markers, the Seurat R package aided in processing scRNA-seq data and identifying TEC clusters. Based on TEC cluster-associated genes identified by Pearson correlation analysis, TEC-related prognostic genes were screened by lasso-Cox regression analysis, thereby constructing a risk signature. A nomogram was created by combining the risk signature with clinicopathological features.

RESULTS

Based on the scRNA-seq data, 5 TEC clusters were discovered in GC, with 3 of them showing prognostic associations in GC. A total of 163 genes were pinpointed among 3302 DEGs as significantly linked to TEC clusters, leading to the formulation of a risk signature comprising 8 genes. Furthermore, there was a notable correlation between the risk signature and the immune cell infiltration. Multivariate analysis findings indicated that the risk signature served as an independent prognostic factor for GC. Moreover, its efficacy in forecasting immune response was validated.

CONCLUSION

TEC-based risk model is highly effective in predicting the survival outcomes of GC patients and can forecast the immune response. Targeting TECs may significantly inhibit tumor progression and enhance the efficacy of immunotherapy.

The roles of epigallocatechin gallate in the tumor microenvironment, metabolic reprogramming, and immunotherapy

Cancer, a disease that modern medicine has not fully understood and conquered, with its high incidence and mortality, deprives countless patients of health and even life. According to global cancer statistics, there were an estimated 19.3 million new cancer cases and nearly 10 million cancer deaths in 2020, with the age-standardized incidence and mortality rates of 201.0 and 100.7 per 100,000, respectively. Although remarkable advancements have been made in therapeutic strategies recently, the overall prognosis of cancer patients remains not optimistic. Consequently, there are still many severe challenges to be faced and difficult problems to be solved in cancer therapy today. Epigallocatechin gallate (EGCG), a natural polyphenol extracted from tea leaves, has received much attention for its antitumor effects. Accumulating investigations have confirmed that EGCG can inhibit tumorigenesis and progression by triggering apoptosis, suppressing proliferation, invasion, and migration, altering tumor epigenetic modification, and overcoming chemotherapy resistance. Nevertheless, its regulatory roles and biomolecular mechanisms in the immune microenvironment, metabolic microenvironment, and immunotherapy remain obscure. In this article, we summarized the most recent updates about the effects of EGCG on tumor microenvironment (TME), metabolic reprogramming, and anti-cancer immunotherapy. The results demonstrated EGCG can promote the anti-cancer immune response of cytotoxic lymphocytes and dendritic cells (DCs), attenuate the immunosuppression of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), and inhibit the tumor-promoting functions of tumor-associated macrophages (TAMs), tumor-associated neutrophils (TANs), and various stromal cells including cancer-associated fibroblasts (CAFs), endothelial cells (ECs), stellate cells, and mesenchymal stem/stromal cells (MSCs). Additionally, EGCG can suppress multiple metabolic reprogramming pathways, including glucose uptake, aerobic glycolysis, glutamine metabolism, fatty acid anabolism, and nucleotide synthesis. Finally, EGCG, as an immunomodulator and immune checkpoint blockade, can enhance immunotherapeutic efficacy and may be a promising candidate for antitumor immunotherapy. In conclusion, EGCG plays versatile regulatory roles in TME and metabolic reprogramming, which provides novel insights and combined therapeutic strategies for cancer immunotherapy.

Lymphatic Endothelial-to-Myofibroblast Transition: A Potential New Mechanism Underlying Skin Fibrosis in Systemic Sclerosis

At present, only a few reports have addressed the possible contribution of the lymphatic vascular system to the pathogenesis of systemic sclerosis (SSc). Based on the evidence that blood vascular endothelial cells can undertake the endothelial-to-myofibroblast transition (EndMT) contributing to SSc-related skin fibrosis, we herein investigated whether the lymphatic endothelium might represent an additional source of profibrotic myofibroblasts through a lymphatic EndMT (Ly-EndMT) process. Skin sections from patients with SSc and healthy donors were immunostained for the lymphatic endothelial cell-specific marker lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) in combination with α-smooth muscle actin (α-SMA) as the main marker of myofibroblasts. Commercial human adult dermal lymphatic microvascular endothelial cells (HdLy-MVECs) were challenged with recombinant human transforming growth factor-β1 (TGFβ1) or serum from SSc patients and healthy donors. The expression of lymphatic endothelial cell/myofibroblast markers was measured by quantitative real-time PCR, Western blotting and immunofluorescence. Collagen gel contraction assay was performed to assess myofibroblast-like cell contractile ability. Lymphatic endothelial cells in intermediate stages of the Ly-EndMT process (i.e., coexpressing LYVE-1 and α-SMA) were found exclusively in the fibrotic skin of SSc patients. The culturing of HdLy-MVECs with SSc serum or profibrotic TGFβ1 led to the acquisition of a myofibroblast-like morphofunctional phenotype, as well as the downregulation of lymphatic endothelial cell-specific markers and the parallel upregulation of myofibroblast markers. In SSc, the Ly-EndMT might represent a previously overlooked pathogenetic process bridging peripheral microlymphatic dysfunction and skin fibrosis development.