ABSTRACT: Tumor microenvironment coevolves with and simultaneously sustains cancer progression. Reactive fibroblasts found in prostate cancer (PCa), known as cancer associated fibroblasts (CAF), have been indeed shown to fuel tumor development and metastasis by mutually interacting with PCa cells. Little is known about the molecular mechanisms that lead to activation of CAFs from tissue-resident fibroblasts, circulating marrow-derived fibroblast progenitors or mesenchymal stem cells. Through integrated gene and microRNA expression profiling, here we showed that transcriptome of CAFs isolated from prostate tumors strictly resembles that of normal fibroblasts stimulated in vitro with interleukin-6 (IL6), thus confirming the capability of the cytokine to promote acquisition of an activated and cancer-promoting phenotype, and, for the first time, proving that IL6 is able per se to induce all the complex transcriptional changes characteristic of patient-derived CAFs. Comparison with publicly available datasets, however, suggested that prostate CAFs may be alternatively characterized by IL6 and TGFβ-related signatures, indicating that either signal, depending on the context, tumor stage and etiology, may concur to fibroblast activation. Our analyses also highlighted pathways relevant for induction of reactive stroma, including genes the role of which in fibroblast activation is still to be explored. In addition, we revealed a role for muscle-specific miR-133b as a soluble factor secreted by activated fibroblasts to support paracrine activation of non-activated fibroblasts or promote tumor progression. Overall, in this study we provided insights on the molecular mechanisms driving fibroblast activation in prostate cancer, thus contributing to identify novel hits for the development of therapeutic strategies targeting the crucial interplay between tumor cells and their microenvironment. Tumor microenvironment coevolves with and simultaneously sustains cancer progression. Reactive fibroblasts found in prostate cancer (PCa), known as cancer associated fibroblasts (CAF), have been indeed shown to fuel tumor development and metastasis by mutually interacting with PCa cells. Little is known about the molecular mechanisms that lead to activation of CAFs from tissue-resident fibroblasts, circulating marrow-derived fibroblast progenitors or mesenchymal stem cells. Through integrated gene and microRNA expression profiling, here we showed that transcriptome of CAFs isolated from prostate tumors strictly resembles that of normal fibroblasts stimulated in vitro with interleukin-6 (IL6), thus confirming the capability of the cytokine to promote acquisition of an activated and cancer-promoting phenotype, and, for the first time, proving that IL6 is able per se to induce all the complex transcriptional changes characteristic of patient-derived CAFs. Comparison with publicly available datasets, however, suggested that prostate CAFs may be alternatively characterized by IL6 and TGFβ-related signatures, indicating that either signal, depending on the context, tumor stage and etiology, may concur to fibroblast activation. Our analyses also highlighted pathways relevant for induction of reactive stroma, including genes the role of which in fibroblast activation is still to be explored. In addition, we revealed a role for muscle-specific miR-133b as a soluble factor secreted by activated fibroblasts to support paracrine activation of non-activated fibroblasts or promote tumor progression. Overall, in this study we provided insights on the molecular mechanisms driving fibroblast activation in prostate cancer, thus contributing to identify novel hits for the development of therapeutic strategies targeting the crucial interplay between tumor cells and their microenvironment. Tumor microenvironment coevolves with and simultaneously sustains cancer progression. Reactive fibroblasts found in prostate cancer (PCa), known as cancer associated fibroblasts (CAF), have been indeed shown to fuel tumor development and metastasis by mutually interacting with PCa cells. Little is known about the molecular mechanisms that lead to activation of CAFs from tissue-resident fibroblasts, circulating marrow-derived fibroblast progenitors or mesenchymal stem cells. Through integrated gene and microRNA expression profiling, here we showed that transcriptome of CAFs isolated from prostate tumors strictly resembles that of normal fibroblasts stimulated in vitro with interleukin-6 (IL6), thus confirming the capability of the cytokine to promote acquisition of an activated and cancer-promoting phenotype, and, for the first time, proving that IL6 is able per se to induce all the complex transcriptional changes characteristic of patient-derived CAFs. Comparison with publicly available datasets, however, suggested that prostate CAFs may be alternatively characterized by IL6 and TGFβ-related signatures, indicating that either signal, depending on the context, tumor stage and etiology, may concur to fibroblast activation. Our analyses also highlighted pathways relevant for induction of reactive stroma, including genes the role of which in fibroblast activation is still to be explored. In addition, we revealed a role for muscle-specific miR-133b as a soluble factor secreted by activated fibroblasts to support paracrine activation of non-activated fibroblasts or promote tumor progression. Overall, in this study we provided insights on the molecular mechanisms driving fibroblast activation in prostate cancer, thus contributing to identify novel hits for the development of therapeutic strategies targeting the crucial interplay between tumor cells and their microenvironment. In the present study, patient derived-CAFs and HPFs activated in vitro with either TGFβ or IL6 were comparatively analyzed for gene and microRNA (miRNA) expression profiles, with the aim to define transcriptional pathways responsible for fibroblast activation and establish whether different subpopulations of CAFs may exist in PCa.
