Fibroblast heterogeneity in prostate carcinogenesis

Prognostic and therapeutic potential of senescent stromal fibroblasts in prostate cancer

The stromal component of the tumour microenvironment in primary and metastatic prostate cancer can influence and promote disease progression. Within the prostatic stroma, fibroblasts are one of the most prevalent cell types associated with precancerous and cancerous lesions; they have a vital role in the structural composition, organization and integrity of the extracellular matrix. Fibroblasts within the tumour microenvironment can undergo cellular senescence, which is a stable arrest of cell growth and a phenomenon that is emerging as a recognized hallmark of cancer. Supporting the idea that cellular senescence has a pro-tumorigenic role, a subset of senescent cells exhibits a senescence-associated secretory phenotype (SASP), which, along with increased inflammation, can promote prostate cancer cell growth and survival. These cellular characteristics make targeting senescent cells and/or modulating SASP attractive as a potential preventive or therapeutic option for prostate cancer.

Comprehensive analyses of the cancer-associated fibroblast subtypes and their score system for prediction of outcomes and immunosuppressive microenvironment in prostate cancer

BACKGROUND

Cancer-associated fibroblasts (CAFs) drive cancer progression and treatment failure on one hand, while their tumor-restraining functions are also observed on the other. Recent single cell RNA sequencing (scRNA-seq) analyses demonstrates heterogeneity of CAFs and defines molecular subtypes of CAFs, which help explain their different functions. However, it remains unclear whether these CAF subtypes have the same or different biological/clinical implications in prostate cancer (PCa) or other malignancies.

METHODS

PCa cells were incubated with supernatant from normal fibroblasts and CAFs to assess their effects on cell behaviors. Sequencing, genomic, and clinical data were collected from TCGA, MSKCC, CPGEA and GEO databases. CAF molecular subtypes and total CAF scores were constructed and grouped into low and high groups based on CAF-specific gene expression. Progression free interval (PFI), clinicopathological features, telomere length, immune cell infiltration, drug treatment and somatic mutations were compared among CAF molecular subtypes and low/high score groups.

RESULTS

The PCa CAF-derived supernatant promoted PCa cell proliferation and invasion. Based on differentially expressed genes identified by scRNA-seq analyses, we classified CAFs into 6 molecular subtypes in PCa tumors, and each subtype was then categorized into score-high and low groups according to the subtype-specific gene expression level. Such score models in 6 CAF subtypes all predicted PFI. Telomeres were significantly shorter in high-score tumors. The total CAF score from 6 CAF subtypes was also associated with PFI in PCa patients inversely, which was consistent with results from cellular experiments. Immunosuppressive microenvironment occurred more frequently in tumors with a high CAF score, which was characterized by increased CTLA4 expression and indicated better responses to CTLA4 inhibitors. Moreover, this model can also serve as a useful PFI predictor in pan-cancers.

CONCLUSION

By combining scRNA-seq and bulk RNA-seq data analyses, we develop a CAF subtype score system as a prognostic factor for PCa and other cancer types. This model system also helps distinguish different immune-suppressive mechanisms in PCa, suggesting its implications in predicting response to immunotherapy. Thus, the present findings should contribute to personalized PCa intervention.

Targeting the tumor microenvironment, a new therapeutic approach for prostate cancer

BACKGROUND

A growing number of studies have shown that in addition to adaptive immune cells such as CD8 + T cells and CD4 + T cells, various other cellular components within prostate cancer (PCa) tumor microenvironment (TME), mainly tumor-associated macrophages (TAMs), cancer-associated fibroblasts (CAFs) and myeloid-derived suppressor cells (MDSCs), have been increasingly recognized as important modulators of tumor progression and promising therapeutic targets.

OBJECTIVE

In this review, we aim to delineate the mechanisms by which TAMs, CAFs and MDSCs interact with PCa cells in the TME, summarize the therapeutic advancements targeting these cells and discuss potential new therapeutic avenues.

METHODS

We searched PubMed for relevant studies published through December 10 2023 on TAMs, CAFs and MDSCs in PCa.

RESULTS

TAMs, CAFs and MDSCs play a critical role in the tumorigenesis, progression, and metastasis of PCa. Moreover, they substantially mediate therapeutic resistance against conventional treatments including anti-androgen therapy, chemotherapy, and immunotherapy. Therapeutic interventions targeting these cellular components have demonstrated promising effects in preclinical models and several clinical trials for PCa, when administrated alone, or combined with other anti-cancer therapies. However, the lack of reliable biomarkers for patient selection and incomplete understanding of the mechanisms underlying the interactions between these cellular components and PCa cells hinder their clinical translation and utility.

CONCLUSION

New therapeutic strategies targeting TAMs, CAFs, and MDSCs in PCa hold promising prospects. Future research endeavors should focus on a more comprehensive exploration of the specific mechanisms by which these cells contribute to PCa, aiming to identify additional drug targets and conduct more clinical trials to validate the safety and efficacy of these treatment strategies.

Single-cell analysis reveals one cancer-associated fibroblasts subtype linked to metastasis in breast cancer: MXRA5 as a potential novel marker for prognosis

Cancer-associated fibroblasts (CAFs) are prevalent in the tumor microenvironment of breast cancer, comprising a group of cell subpopulations with spatial, phenotypic, and functional heterogeneity. Due to the lack of specific markers for CAF subpopulations, their specific mechanisms in breast cancer remain unclear. We identified eight distinct CAF phenotypes in breast cancer using multiple single-cell RNA sequencing datasets and determined distinct transcription factors (TFs) of CAFs through SCENIC analysis. Our study highlights one CAF subtype in breast cancer, FN1+CAF2, associated with metastasis and macrophage polarization. We observed elevated FN1 expression in the stromal tissue of breast cancer patients. Furthermore, FN1 knockdown in CAFs reduced the migration ability of breast cancer cells. We identified a regulatory gene, MXRA5, in CAF2, which may play crucial roles in breast cancer. Our results indicated upregulated MXRA5 expression in breast cancer tissues and CAFs from patients with lymph node metastasis in the following experiment. Overall, our study reveals that the FN1+CAF2 subtype is associated with metastasis and suggests that MXRA5 may be a novel marker mediating the effects of CAF2 on breast cancer metastasis. This study enriches our understanding of CAF heterogeneity and offers new insights for treating breast cancer metastasis.

Downregulation of S100A11 promotes T cell infiltration by regulating cancer-associated fibroblasts in prostate cancer

OBJECTIVE

This study aims at revealing the relationship between S100A11 and cancer-associated fibroblasts (CAFs) in prostate cancer and improving T cell infiltration into solid tumors.

METHODS

H&E, IHC and Sirius red staining were used to detect the stroma content in prostate cancer tissues. Stable S100A11 knockdown cell lines DU 145, 22Rv1, RM-1 and NOR-10 were established by lentivirus transfection. Co-culture system of RM-1 and CAFs was established. CCK-8, wound healing and transwell were proceeded to determine proliferation, migration and invasion of prostate cancer cells. Stably knocked-down RM-1 and CAFs were co-injected into C57BL/6 mice to detect the role of S100A11 in vivo. CAFs, CD4+ T cell and CD8+ T cell in these tumors were assessed by IF. T cell profile was analyzed by flow cytometry.

RESULTS

A significant amount of stroma exists in prostate cancer tissues. Downregulation of S100A11 inhibits proliferation, migration and invasion of human prostate cancer cells in vitro, and suppresses the expression of cancer-associated fibroblasts (CAFs) in vivo. Knockdown of S100A11 enhances the inhibitory effect of Erdafitinib on CAFs in both the co-culture system and in vivo. The combined knockdown of S100A11 in tumor cells and CAFs shows a superior therapeutic effect compared to the individual knockdown in tumor cells alone. Knockdown of S100A11, both in RM-1 and CAFs, combined with Erdafitinib treatment reduces tumorigenicity by suppressing the content of CAFs and increasing the infiltration of CD4+ T cell and effective CD8+ T cell in tumor.

CONCLUSION

Downregulation of S100A11 plays a crucial role in enhancing the therapeutic response to Erdafitinib and reversing immunosuppressive tumor microenvironment.

Cancer-Associated Fibroblast: Role in Prostate Cancer Progression to Metastatic Disease and Therapeutic Resistance

Prostate cancer (PCa) is one of the most common cancers in European males. Although therapeutic approaches have changed in recent years, and several new drugs have been approved by the Food and Drug Administration (FDA), androgen deprivation therapy (ADT) remains the standard of care. Currently, PCa represents a clinical and economic burden due to the development of resistance to ADT, paving the way to cancer progression, metastasis, and to long-term side effects induced by ADT and radio-chemotherapeutic regimens. In light of this, a growing number of studies are focusing on the tumor microenvironment (TME) because of its role in supporting tumor growth. Cancer-associated fibroblasts (CAFs) have a central function in the TME because they communicate with prostate cancer cells, altering their metabolism and sensitivity to drugs; hence, targeted therapy against the TME, and, in particular, CAFs, could represent an alternative therapeutic approach to defeat therapy resistance in PCa. In this review, we focus on different CAF origins, subsets, and functions to highlight their potential in future therapeutic strategies for prostate cancer.

Exploring prostate cancer in the post-genomic era

In the Special Issue on Prostate Cancer, we have invited 25 researchers or clinicians from prostate cancer community to review the cutting-edge topics in this field. In particular, the mini-reviews have covered various basic science and clinical aspects in prostate cancer, including prostate epithelial stem cells or progenitors, androgen and androgen receptor pathways, tumor modeling, genomics, different cell-autonomous and non-cell-autonomous mechanisms as well as various clinical issues encompassing diagnosis, risk stratification and treatments.

Cancer-Associated Fibroblast Heterogeneity, Activation and Function: Implications for Prostate Cancer

The continuous remodeling of the tumor microenvironment (TME) during prostate tumorigenesis is emerging as a critical event that facilitates cancer growth, progression and drug-resistance. Recent advances have identified extensive communication networks that enable tumor-stroma cross-talk, and emphasized the functional importance of diverse, heterogeneous stromal fibroblast populations during malignant growth. Cancer-associated fibroblasts (CAFs) are a vital component of the TME, which mediate key oncogenic events including angiogenesis, immunosuppression, metastatic progression and therapeutic resistance, thus presenting an attractive therapeutic target. Nevertheless, how fibroblast heterogeneity, recruitment, cell-of-origin and differential functions contribute to prostate cancer remains to be fully delineated. Developing our molecular understanding of these processes is fundamental to developing new therapies and biomarkers that can ultimately improve clinical outcomes. In this review, we explore the current challenges surrounding fibroblast identification, discuss new mechanistic insights into fibroblast functions during normal prostate tissue homeostasis and tumorigenesis, and illustrate the diverse nature of fibroblast recruitment and CAF generation. We also highlight the promise of CAF-targeted therapies for the treatment of prostate cancer.

YAP1-TEAD1 mediates the perineural invasion of prostate cancer cells induced by cancer-associated fibroblasts

Perineural invasion (PNI) driven by the tumor microenvironment (TME) has emerged as a key pattern of metastasis of prostate cancer (PCa), while its underlying mechanism is still elusive. Here, we identified increased CAFs and YAP1 expression levels in patients with metastatic PCa. In the cultured PCa cell line LNCaP, co-culture with cancer-associated fibroblasts (CAFs) could upregulate YAP1 protein expression. Either ectopic overexpression of YAP1 or co-culture with CAFs could promote the infiltration of LNCaPs towards dorsal root ganglia (DRG). This effect could be blocked using an YAP1 inhibitor. In vivo, overexpression of YAP1 could increase PNI in a mouse model of sciatic nerve tumor invasion. Mechanistically, TEAD1 binds to the NGF promotor and YAP1/TEAD1 activates its transcription and consequently increases NGF secretion. In turn, PCa cells treated with CM from CAFs or stable YAP1 overexpression can stimulate DRG to secrete CCL2. The epithelial-to-mesenchymal transition (EMT) of PCa cells is thus activated via CCL2/CCR2. Overall, our data demonstrate that CAFs can activate YAP1/TEAD1 signaling and increase the secretion of NGF, therefore promoting PCa PNI. In addition, EMT induced by PNI suggests a feedback loop is present between neurons and PCa cells.

Ephrin B Activate Src Family Kinases in Fibroblasts Inducing Stromal Remodeling in Prostate Cancer

Simple Summary

Carcinoma associated fibroblasts (CAF) play a critical role in the tumor microenvironment (TME) of prostate cancer (PCa). Ephrin receptors (Eph) and ligands (EFN) have been implicated in distinct types of cancers. Alterations on EphB receptors are frequently found in PCa, but the role of ligands (EFNB1, EFNB2, EFNB3) activation in prostate fibroblasts and consequent effects on PCa is not known. We found increased EFNB ligands in fibroblasts isolated from PCa tissues. In this study, we assessed the effects of elevated stromal EFNB ligands on PCa tumor growth. Increased EFNB1 and EFNB3 expression transformed normal fibroblasts into CAF phenotypes through activation of Src family kinases. The secretome of EFNB-expressing CAF increased PCa cell proliferation and promoted TME remodeling. Overall, EFNB activation in CAF may participate in PCa progression via the release of soluble factors that modulate the surrounding tumor environment, which, in turn, promote prostate tumor growth and invasion.

Abstract

Through stromal-epithelial interactions, carcinoma associated fibroblasts (CAF) play a critical role in tumor growth and progression. Activation of erythrophoyetin-producing human hepatocellular (Eph) receptors has been implicated in cancer. Eph receptor interactions with Ephrin ligands lead to bidirectional signals in the recipient and effector cells. The consequences of continuous reverse Ephrin signaling activation in fibroblasts on prostate cancer (PCa) is unknown. When compared to benign prostate fibroblast, CAF displayed higher expression of Ephrin B1, B2, and B3 ligands (EFNB1, EFNB2, and EFNB3). In this study, we found that continuous activation of EFNB1 and EFNB3 in a benign human prostate stromal cell line (BHPrS1) increased the expression of CAF markers and induced a CAF phenotype. BHPrS1^EFNB1 and BHPrS1^EFNB3 displayed a pro-tumorigenic secretome with multiple effects on neovascularization, collagen deposition, and cancer cell proliferation, overall increasing tumorigenicity of a premalignant prostate epithelial cell line BPH1 and PCa cell line LNCaP, both in vitro and in vivo. Inhibition of Src family kinases (SFK) in BHPrS1^EFNB1 and BHPrS1^EFNB3 suppressed EFNB-induced ɑ-SMA (Alpha-smooth muscle actin) and TN-C (Tenascin-C) in vitro. Our study suggests that acquisition of CAF characteristics via SFK activation in response to increased EFNB ligands could promote carcinogenesis via modulation of TME in PCa.