Matrix remodeling-associated protein 8 is a marker of a subset of cancer-associated fibroblasts in pancreatic cancer

Proteomic analysis of pleomorphic dermal sarcoma reveals a fibroblastic cell of origin and distinct immune evasion mechanisms

Pleomorphic dermal sarcomas are infrequent neoplastic skin tumors, manifesting in regions of the skin exposed to ultraviolet radiation. Diagnosing the entity can be challenging and therapeutic options are limited. We analyzed 20 samples of normal healthy skin tissue (SNT), 27 malignant melanomas (MM), 20 cutaneous squamous cell carcinomas (cSCC), and 24 pleomorphic dermal sarcomas (PDS) using mass spectrometry. We explored a potential cell of origin in PDS and validated our findings using publicly available single-cell sequencing data. By correlating tumor purity (TP), inferred by both RNA- and DNA-sequencing, to protein abundance, we found that fibroblasts shared most of the proteins correlating to TP. This observation could also be made using publicly available SNT single cell sequencing data. Moreover, we studied relevant pathways of receptor/ligand (R/L) interactions. Analysis of R/L interactions revealed distinct pathways in cSCC, MM and PDS, with a prominent role of PDGFRB-PDGFD R/L interactions and upregulation of PI3K/AKT signaling pathway. By studying differentially expressed proteins between cSCC and PDS, markers such as MAP1B could differentiate between these two entities. To this end, we studied proteins associated with immunosuppression in PDS, uncovering that immunologically cold PDS cases shared a "negative regulation of interferon-gamma signaling" according to overrepresentation analysis.

Proteogenomic analysis of enriched HGSOC tumor epithelium identifies prognostic signatures and therapeutic vulnerabilities

We performed a deep proteogenomic analysis of bulk tumor and laser microdissection enriched tumor cell populations from high-grade serous ovarian cancer (HGSOC) tissue specimens spanning a broad spectrum of purity. We identified patients with longer progression-free survival had increased immune-related signatures and validated proteins correlating with tumor-infiltrating lymphocytes in 65 tumors from an independent cohort of HGSOC patients, as well as with overall survival in an additional 126 HGSOC patient cohort. We identified that homologous recombination deficient (HRD) tumors are enriched in pathways associated with metabolism and oxidative phosphorylation that we validated in independent patient cohorts. We further identified that polycomb complex protein BMI-1 is elevated in HR proficient (HRP) tumors, that elevated BMI-1 correlates with poor overall survival in HRP but not HRD HGSOC patients, and that HRP HGSOC cells are uniquely sensitive to BMI-1 inhibition.

Meflin is a marker of pancreatic stellate cells involved in fibrosis and epithelial regeneration in the pancreas

Pancreatic stellate cells (PSCs) are stromal cells in the pancreas that play an important role in pancreatic pathology. In chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma (PDAC), PSCs are known to get activated to form myofibroblasts or cancer-associated fibroblasts (CAFs) that promote stromal fibroinflammatory reactions. However, previous studies on PSCs were mainly based on the findings obtained using ex vivo expanded PSCs, with few studies that addressed the significance of in situ tissue-resident PSCs using animal models. Their contributions to fibrotic reactions in CP and PDAC are also lesser-known. These limitations in our understanding of PSC biology have been attributed to the lack of specific molecular markers of PSCs. Herein, we established Meflin (Islr), a glycosylphosphatidylinositol-anchored membrane protein, as a PSC-specific marker in both mouse and human by using human pancreatic tissue samples and Meflin reporter mice. Meflin-positive (Meflin+ ) cells contain lipid droplets and express the conventional PSC marker Desmin in normal mouse pancreas, with some cells also positive for Gli1, the marker of pancreatic tissue-resident fibroblasts. Three-dimensional analysis of the cleared pancreas of Meflin reporter mice showed that Meflin+ PSCs have long and thin cytoplasmic protrusions, and are localised on the abluminal side of vessels in the normal pancreas. Lineage tracing experiments revealed that Meflin+ PSCs constitute one of the origins of fibroblasts and CAFs in CP and PDAC, respectively. In these diseases, Meflin+ PSC-derived fibroblasts showed a distinctive morphology and distribution from Meflin+ PSCs in the normal pancreas. Furthermore, we showed that the genetic depletion of Meflin+ PSCs accelerated fibrosis and attenuated epithelial regeneration and stromal R-spondin 3 expression, thereby implying that Meflin+ PSCs and their lineage cells may support tissue recovery and Wnt/R-spondin signalling after pancreatic injury and PDAC development. Together, these data indicate that Meflin may be a marker specific to tissue-resident PSCs and useful for studying their biology in both health and disease. © 2023 The Pathological Society of Great Britain and Ireland.

The Role of Different Immunocompetent Cell Populations in the Pathogenesis of Head and Neck Cancer-Regulatory Mechanisms of Pro- and Anti-Cancer Activity and Their Impact on Immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive and heterogeneous groups of human neoplasms. HNSCC is characterized by high morbidity, accounting for 3% of all cancers, and high mortality with ~1.5% of all cancer deaths. It was the most common cancer worldwide in 2020, according to the latest GLOBOCAN data, representing the seventh most prevalent human malignancy. Despite great advances in surgical techniques and the application of modern combinations and cytotoxic therapies, HNSCC remains a leading cause of death worldwide with a low overall survival rate not exceeding 40-60% of the patient population. The most common causes of death in patients are its frequent nodal metastases and local neoplastic recurrences, as well as the relatively low response to treatment and severe drug resistance. Much evidence suggests that the tumour microenvironment (TME), tumour infiltrating lymphocytes (TILs) and circulating various subpopulations of immunocompetent cells, such regulatory T cells (CD4+CD25+Foxp3+Tregs), cytotoxic CD3+CD8+ T cells (CTLs) and CD3+CD4+ T helper type 1/2/9/17 (Th1/Th2/Th9/Th17) lymphocytes, T follicular helper cells (Tfh) and CD56dim/CD16bright activated natural killer cells (NK), carcinoma-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), tumour-associated neutrophils (N1/N2 TANs), as well as tumour-associated macrophages (M1/M2 phenotype TAMs) can affect initiation, progression and spread of HNSCC and determine the response to immunotherapy. Rapid advances in the field of immuno-oncology and the constantly growing knowledge of the immunosuppressive mechanisms and effects of tumour cancer have allowed for the use of effective and personalized immunotherapy as a first-line therapeutic procedure or an essential component of a combination therapy for primary, relapsed and metastatic HNSCC. This review presents the latest reports and molecular studies regarding the anti-tumour role of selected subpopulations of immunocompetent cells in the pathogenesis of HNSCC, including HPV+ve (HPV+) and HPV-ve (HPV-) tumours. The article focuses on the crucial regulatory mechanisms of pro- and anti-tumour activity, key genetic or epigenetic changes that favour tumour immune escape, and the strategies that the tumour employs to avoid recognition by immunocompetent cells, as well as resistance mechanisms to T and NK cell-based immunotherapy in HNSCC. The present review also provides an overview of the pre- and clinical early trials (I/II phase) and phase-III clinical trials published in this arena, which highlight the unprecedented effectiveness and limitations of immunotherapy in HNSCC, and the emerging issues facing the field of HNSCC immuno-oncology.

MXRA8 is an immune-relative prognostic biomarker associated with metastasis and CD8+ T cell infiltration in colorectal cancer

Background

Colorectal cancer (CRC) is the second most common cause of cancer-related deaths worldwide. Tumor metastasis and CD8⁺ T cell infiltration play a crucial role in CRC patient survival. It is important to determine the etiology and mechanism of the malignant progression of CRC to develop more effective treatment strategies.

Methods

We conducted weighted gene co-expression network analysis (WGCNA) to explore vital modules of tumor metastasis and CD8⁺ T cell infiltration, then with hub gene selection and survival analysis. Multi-omics analysis is used to explore the expression pattern, immunity, and prognostic effect of MXRA8. The molecular and immune characteristics of MXRA8 are analyzed in independent cohorts, clinical specimens, and in vitro.

Results

MXRA8 expression was strongly correlated with tumor malignancy, metastasis, recurrence, and immunosuppressive microenvironment. Furthermore, MXRA8 expression predicts poor prognosis and is an independent prognostic factor for OS in CRC.

Conclusion

MXRA8 may be a potential immunotherapeutic and prognostic biomarker for CRC.

Possible disease-protective roles of fibroblasts in cancer and fibrosis and their therapeutic application

Cancer and fibrotic diseases are characterized by continuous inflammation, tissue wounds, and injuries. Cancer is a "wound that does not heal," and the uncontrolled proliferation of cancer cells disrupts normal tissue integrity and induces stromal fibroinflammatory reactions. Fibroblasts proliferate extensively in the stroma, playing a major role in the development of these diseases. There has been considerable evidence that fibroblasts contribute to fibrosis and tissue stiffening and promote disease progression via multiple mechanisms. However, recent emerging findings, mainly derived from single-cell transcriptomic analysis, indicated that fibroblasts are functionally heterogeneous, leading to the hypothesis that both disease-promoting and -restraining fibroblasts exist. We recently showed that a fibroblast population, defined by the expression of the glycosylphosphatidylinositol-anchored membrane protein Meflin may suppress but not promote fibrotic response and disease progression in cancer and fibrotic diseases. Although currently hypothetical, the primary function of Meflin-positive fibroblasts may be tissue repair after injury and cancer initiation occurred. This observation has led to the proposal of a potential therapy that converts the phenotype of fibroblasts from pro-tumor to anti-tumor. In this short review, we summarize our recent findings on the function of Meflin in the context of cancer and fibrotic diseases and discuss how we can utilize this knowledge on fibroblasts in translational medicine. We also discuss several aspects of the interpretation of survival analysis data, such as Kaplan-Meier analysis, to address the function of specific genes expressed in fibroblasts.

Good and Bad Stroma in Pancreatic Cancer: Relevance of Functional States of Cancer-Associated Fibroblasts

Simple Summary

Recent progress in research on the biology of cancer-associated fibroblasts (CAFs) in pancreatic ductal adenocarcinoma (PDAC) indicates their diverse states and plasticity, which may lead to good and bad stroma, suppressing and promoting cancer progression, respectively. The characteristics of the stroma differ spatially, even within the same tumors, based on the balance between cancer-restraining CAF and cancer-promoting CAF proliferation at the site. These heterogeneous CAFs also influence the sensitivity of PDAC to anticancer therapeutics. Further preclinical and clinical studies will advance our understanding of the roles of CAFs in disease progression and aid the development of therapeutics that modulate or ameliorate the tumor microenvironment in PDAC.

Abstract

A well-known feature of human pancreatic ductal adenocarcinoma (PDAC) is the extensive proliferation of cancer-associated fibroblasts (CAFs) and highly fibrotic stroma. Recent evidence, based mainly on single-cell analyses, has identified various subsets of CAFs in PDAC mouse models. However, we do not know how these CAF subsets are involved in the progression and drug resistance of human PDAC. Additionally, it remains unclear whether these diverse CAFs have distinct origins and are indicators of genuinely distinct CAF lineages or reflect different states of the same CAFs depending on the tumor microenvironment. Interestingly, recent preclinical studies have started to characterize the nature of cancer-restraining CAFs and have identified their markers Meflin and collagen type I alpha 1. These studies have led to the development of strategies to induce changes in CAF phenotypes using chemical reagents or recombinant viruses, and some of them have been tested in clinical studies. These strategies have the unique potential to convert the so-called bad stroma to good stroma and may also have therapeutic implications for non-cancer diseases such as fibrotic diseases. Together with recently developed sophisticated strategies that specifically target distinct CAF subsets via adoptive cell transfer therapy, vaccination, and antibody–drug conjugates, any future findings arising from these clinical efforts may expand our understanding of the significance of CAF diversity in human PDAC.

A novel renal perivascular mesenchymal cell subset gives rise to fibroblasts distinct from classic myofibroblasts

Perivascular mesenchymal cells (PMCs), which include pericytes, give rise to myofibroblasts that contribute to chronic kidney disease progression. Several PMC markers have been identified; however, PMC heterogeneity and functions are not fully understood. Here, we describe a novel subset of renal PMCs that express Meflin, a glycosylphosphatidylinositol-anchored protein that was recently identified as a marker of fibroblasts essential for cardiac tissue repair. Tracing the lineage of Meflin⁺ PMCs, which are found in perivascular and periglomerular areas and exhibit renin-producing potential, showed that they detach from the vasculature and proliferate under disease conditions. Although the contribution of Meflin⁺ PMCs to conventional α-SMA⁺ myofibroblasts is low, they give rise to fibroblasts with heterogeneous α-SMA expression patterns. Genetic ablation of Meflin⁺ PMCs in a renal fibrosis mouse model revealed their essential role in collagen production. Consistent with this, human biopsy samples showed that progressive renal diseases exhibit high Meflin expression. Furthermore, Meflin overexpression in kidney fibroblasts promoted bone morphogenetic protein 7 signals and suppressed myofibroblastic differentiation, implicating the roles of Meflin in suppressing tissue fibrosis. These findings demonstrate that Meflin marks a PMC subset that is functionally distinct from classic pericytes and myofibroblasts, highlighting the importance of elucidating PMC heterogeneity.

Meflin-positive cancer-associated fibroblasts enhance tumor response to immune checkpoint blockade

Meflin/ISLR is the marker of a cancer-associated fibroblast subset that enhances tumor response to immune checkpoint blockade therapy.

Cancer-associated fibroblasts (CAFs) are an integral component of the tumor microenvironment (TME). Most CAFs shape the TME toward an immunosuppressive milieu and attenuate the efficacy of immune checkpoint blockade (ICB) therapy. However, the detailed mechanism of how heterogeneous CAFs regulate tumor response to ICB therapy has not been defined. Here, we show that a recently defined CAF subset characterized by the expression of Meflin, a glycosylphosphatidylinositol-anchored protein marker of mesenchymal stromal/stem cells, is associated with survival and favorable therapeutic response to ICB monotherapy in patients with non-small cell lung cancer (NSCLC). The prevalence of Meflin-positive CAFs was positively correlated with CD4-positive T-cell infiltration and vascularization within non-small cell lung cancer tumors. Meflin deficiency and CAF-specific Meflin overexpression resulted in defective and enhanced ICB therapy responses in syngeneic tumors in mice, respectively. These findings suggest the presence of a CAF subset that promotes ICB therapy efficacy, which adds to our understanding of CAF functions and heterogeneity.