The androgen receptor (AR) signaling pathway is critical for growth and differentiation of prostate cancer cells. For that reason, androgen deprivation therapy with medical or surgical castration is the principal treatment for metastatic prostate cancer. More recently, new potent AR signaling inhibitors (ARSIs) have been developed. These drugs improve survival for men with metastatic castration-resistant prostate cancer (CRPC), the lethal form of the disease. However, ARSI resistance is nearly universal. One recently appreciated resistance mechanism is lineage plasticity or switch from an AR-driven, luminal differentiation program to an alternate differentiation program. Importantly, lineage plasticity appears to be increasing in incidence in the era of new ARSIs, strongly implicating AR suppression in this process. Lineage plasticity and shift from AR-driven tumors occur on a continuum, ranging from AR-expressing tumors with low AR activity to AR-null tumors that have activation of alternate differentiation programs versus the canonical luminal program found in AR-driven tumors. In many cases, AR loss coincides with the activation of a neuronal program, most commonly exemplified as therapy-induced neuroendocrine prostate cancer (t-NEPC). While genetic events clearly contribute to prostate cancer lineage plasticity, it is also clear that epigenetic events—including chromatin modifications and DNA methylation—play a major role. Many epigenetic factors are now targetable with drugs, establishing the importance of clarifying critical epigenetic factors that promote lineage plasticity. Furthermore, epigenetic marks are readily measurable, demonstrating the importance of clarifying which measurements will help to identify tumors that have undergone or are at risk of undergoing lineage plasticity. In this review, we discuss the role of AR pathway loss and activation of a neuronal differentiation program as key contributors to t-NEPC lineage plasticity. We also discuss new epigenetic therapeutic strategies to reverse lineage plasticity, including those that have recently entered clinical trials.
Background: Sarcomatoid renal cell carcinoma (sRCC) is thought to arise by epithelial to mesenchymal transition (EMT) of the parental tumor in diverse RCC including clear cell RCC (ccRCC). sRCC is also known to be highly immunogenic and also express high levels of inflammatory pathway genes. Cells undergoing EMT and immune cells can have reciprocal feedback on each other; however, the role of such crosstalk in sRCC is unknown. Here, we use single cell spatial transcriptomics to evaluate the heterogeneity of EMT within sRCC in correlation with the immune microenvironment and in-vitro studies to explore mechanisms of crosstalk. Methods: A sRCC nephrectomy specimen was subjected to single cell spatial transcriptomics of 1000 mRNA targets (NanoString CosMX). Semi-supervised clustering was performed and cell types were assigned by reference to single cell RNAseq data and then mapped spatially. Differential gene expression and cell to cell distance analysis was performed. In-vitro assays included treatment of 786-O and Caki-1 ccRCC lines with recombinant SPP1 and protein and mRNA analysis. Results: Histopathologic evaluation revealed a ccRCC zone, a transition zone (tz) between the ccRCC and sRCC in which the ccRCC cells gained an increased mesenchymal morphology, and a well-developed sRCC zone. Transcriptomic data revealed four distinct tumor cell populations: a ccRCC, a tzRCC, and two sRCC populations. Importantly, a subset of the histologically-categorized ccRCC had a tzRCC transcriptional signature, demonstrating this signature is identifiable prior to development of morphologic features of sRCC. FZD4, a factor that may function in preventing EMT, was uniquely expressed on ccRCC and lost in tzRCC and sRCC cells. CCL20, a promoter of macrophage recruitment, was highly expressed in tzRCC. Distance analysis showed macrophages were highly spatially correlated with tzRCC and sRCC cells. Macrophages near tzRCC differentially expressed SPP1. In-vitro treatment of ccRCC cells with recombinant SPP1 led to induction of EMT and further upregulation of CCL20 expression. Conclusion: We report a unique tumor cell population characterized by ccRCC morphology but harboring a transcriptome suggestive of progression towards sRCC. This provides rationale for the development of a novel molecular signature to subclassify ccRCC. We identified FZD4, CCL20 and SPP1 as key genes in the transition of ccRCC to sRCC which may mediate crosstalk between RCC cells and macrophages, with potential for therapeutic targets. Citation Format: Allison May, Claire Williams, Stephanie The, Sean Kim, Nathan Schurman, Greg Shelley, Tyler Robinson, Simpa Salami, Rohit Mehra, Aaron Udager, Evan Keller. Spatial analysis of the immune microenvironment and tumor cell transition in sarcomatoid renal cell carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4700.
Intro: Sarcomatoid de-differentiation in renal cell carcinoma (sRCC) leads to aggressive tumors that may be uniquely responsive to adjuvant immunotherapy. sRCC is thought to arise by epithelial to mesenchymal transition (EMT) of the parental tumor, most commonly clear cell RCC (ccRCC). However, factors that drive sRCC are unknown and no biomarkers exist to predict the transition. Furthermore, the immune microenvironment in sRCC is not well understood and may provide additional therapeutic targets. Here, we use spatial biology and in vitro studies to explore EMT/immune cell crosstalk in sRCC. Methods: Single cell spatial transcriptomics was performed on a human sRCC specimen with Nanostring CosMx platform. Semi-supervised clustering referenced to scRNAseq data was used to define cell types and map them spatially. Differential gene expression and cell distance analysis were performed. Multiplex immunofluorescent staining (mIF) was performed by Vectra Polaris. In vitro work used ccRCC cell line, 786-O, and sRCC cell line, UOK-127. M0, M1, or M2 macrophages were derived from THP-1 cells. Analysis of macrophage markers and EMT markers were performed by western blot and RT-qPCR. Results: Single cell spatial transcriptomic data revealed a ccRCC population, 2 sRCC cell types, and a novel transitional cell type along the EMT continuum and spatially between ccRCC and sRCC. Importantly, matched H&E shows the transitional cell type present in areas histologically defined as ccRCC, demonstrating molecular evidence of transition towards sRCC prior to histologic changes. Cell to cell distance revealed strong correlation of M2 macrophages with transitional and sRCC cells. The ccRCC population expressed CCL20, a factor known to assist in macrophage recruitment, and CCL20 was upregulated in the transitional cell type. FZD4 was the highest fold changed gene lost from the ccRCC to transitional cells. In vitro culture of RCC cells with M2 macrophages led to CCL20 upregulation and loss of FZD4. Overexpression of CCL20 and knockdown of FZD4 in RCC cells both led to EMT. Exposure of macrophages to CCL20 led to M2 polarization. To validate the role of these genes, analysis of the human protein atlas (877 RCC specimens) revealed high expression of CCL20 and low expression of FZD4 are both associated with poor survival. mIF of 20 human sRCC specimens demonstrated CD163 (M2 macrophage marker) was associated with sRCC or ccRCC areas with high expression of mesenchymal marker N-cadherin. Conclusion: We report the first detection of a transitional cell type along the de-differentiation pathway from ccRCC to sRCC. This cell type is detectable in areas histologically defined as ccRCC, demonstrating strong potential as a transcriptional biomarker to inform adjuvant immunotherapy. We show that CCL20 on tumor cells leads to macrophage recruitment and polarization, resulting in FZD4 loss and CCL20 upregulation, which induce EMT and propagates a vicious cycle of EMT/macrophage crosstalk in sRCC. This suggests potential for therapeutic targeting of macrophages or CCL20 in RCC. Citation Format: Allison May, Claire Williams, Stephanie The, Jake McGue, Sean Kim, Nathan Schurman, Greg Shelley, Tyler Robinson, Simpa Salami, Rohit Mehra, Timothy Frankel, Aaron Udager, Evan Keller. Macrophage induced epithelial to mesenchymal transition in sarcomatoid renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr PR014.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.