Patterns of stemness‐associated markers in the development of castration‐resistant prostate cancer

Abstract

BackgroundPutative castration‐resistant (CR) stem‐like cells (CRSC) have been identified based on their ability to initiate and drive prostate cancer (PCa) recurrence following castration in vivo. Yet the relevance of these CRSC in the course of the human disease and particularly for the transition from hormone‐naive (HN) to castration‐resistance is unclear. In this study, we aimed at deciphering the significance of CRSC markers in PCa progression.MethodsWe constructed a tissue microarray comprising 112 matched HN and CR tissue specimens derived from 55 PCa patients. Expression of eight stemness‐associated markers (ALDH1A1, ALDH1A3, ALDH3A1, BMI1, NANOG, NKX3.1, OCT4, SOX2) was assessed by immunohistochemistry and scored as a percentage of positive tumor cells. For each marker, the resulting scores were statistically analyzed and compared to pathological and clinical data associated with the samples. Unsupervised clustering analysis was performed to stratify patients according to the expression of the eight CRSC markers. Publicly‐available transcriptional datasets comprising HN and CR PCa samples were interrogated to assess the expression of the factors in silico.ResultsImmunohistochemical assessment of paired samples revealed atypical patterns of expression and intra‐ and intertumor heterogeneity for a subset of CRSC markers. While the expression of particular CRSC markers was dynamic over time in some patients, none of the markers showed significant changes in expression upon the development of castration resistance (CR vs HN). Using unsupervised clustering approaches, we identified phenotypic subtypes based on the expression of specific stem‐associated markers. In particular, we found (a) patterns of mutual exclusivity for ALDH1A1 and ALDH1A3 expression, which was also observed at the transcriptomic level in publicly‐available PCa datasets, and (b) a phenotypic cluster associated with more aggressive features. Finally, by comparing HN and CR matched samples, we identified phenotypic cluster switches (ie, change of phenotypic cluster between the HN and CR state), that may be associated with clinical and predictive relevance.ConclusionsOur findings indicate stemness‐associated patterns that are associated with the development of castration‐resistance. These results pave the way toward a deeper understanding of the relevance of CRSC markers in PCa progression and resistance to androgen‐deprivation therapy.

The distinct role of ALDH1A1 and ALDH1A3 in the regulation of prostate cancer metastases

“…Consistently with those findings, Magnen and co-authors found an association of ALDH1A1 with higher-grade tumors (Magnen et al, 2013). A recent study by Federer-Gsponer also indicated patterns of mutual exclusivity for ALDH1A1 and ALDH1A3 expression across several datasets (Federer-Gsponer et al, 2020). However, the relationship between ALDH genes and bone metastatic tumor growth was unknown.…”

The Role of Nkx3.1 in Cancers and Stemness

“…Besides Nkx3.1-expressing CARNs, other forms of cancer stem cell (CSC) have been identified that give rise to castration-resistant prostate cancers (CRPC). One such example includes cancer-associated fibroblasts (CAF) (83)(84)(85).…”

Dynamic prostate cancer transcriptome analysis delineates the trajectory to disease progression.

“…Because EZH2 was not assessed in this dataset, we ascertained its upregulation with disease progression on a tissue microarray of 33 primary and matched CRPC samples ( Supplementary Fig. 1G) 36 .…”

“…Immunohistochemically staining EZH2 protein expression was analyzed on a previously described tissue microarray including, matched primary and CRPC samples 36 . All prostate cancer samples were obtained under approval by the Ethics Committee of Northwestern and Central Switzerland (EKNZ, No EK/1311 and 2015/228).…”

“…Lines PC3, DU-145, 22rV1, MDA-PCa-2b, LAPC-4, LNCaP, VCaP, and HEK 293T cell lines were purchased from ATCC (American Tissue Culture Collection) (Manassas, USA). The LAPC-4 cell line was a gift from Prof. Helmut Klocker while the LNCaP-abl cell line was a gift from Prof. Myles Brown (DFCI, Boston).Immunohistochemically staining EZH2 protein expression was analyzed on a previously described tissue microarray including, matched primary and CRPC samples36 . All prostate cancer samples were obtained under approval by the Ethics Committee of Northwestern and Central Switzerland (EKNZ, No EK/1311 and 2015/228).…”