Essential role of p53 of stromal fibroblasts (fibs) in the reciprocal interaction between PC3 prostate cancer cells and stromal fibs.

Abstract

e21009 Background: The p53/p21 regulatory network is frequently deregulated in stromal cells and aberrant expression of p53/p21 has been reported in stromal fibs in various cancers. Methods: In order to provide hints regarding the mode of the paracrine interaction between p53 in stromal fibs and cancer cells (ccs), primary fibs from mice differing in the status of p53 were cultured in the presence of conditioned media from PC3 human prostate ccs and the rate of cell growth was evaluated. In addition, in vitro wound healing assays were performed to assess motility and migration of ccs. Considering the effects of p53-deficient (p53d) fibs in the phenotype of PC3 cells, we also searched if this paracrine stimulatory mechanism also affects viability of PC3 cells bearing stem cell-like properties by flow-cytometry. Therefore, PC3 cells that is CD44(hi)/CD44(low) were assessed in cells co-cultured with wild-type or p53d fibs. Results: We showed that p53d fibs acquire proliferative advantage when cultured in the presence of PC3 media, an observation likely related to the predominance of cells bearing this alteration in the microenvironment. The reverse experiment, i.e. the culture of PC3 cells in the presence of conditioned media from wild-type or p53-null fibs indicated that the latter stimulate the proliferation of ccs establishing a paracrine reciprocal stimulatory network that facilitates tumor growth. In vitro wound healing assays revealed that media from p53d cells significantly stimulated PC3 cell migration that reflects the degree of cellular motility which is associated with the metastatic potential of ccs. Flow-cytometry demonstrated that although wild fibs reduced the fraction of CD44(hi)/CD44(low) cells compared to that of PC3 cells cultured alone, the presence of p53d fibs restored the CD44(hi)/CD44(low) cell content to levels similar to those of the controls. Conclusions: Our findings pose that deregulated expression and mutations in p53 and/or p21 in stromal fibs are causatively linked to tumor growth, affecting not only cellular proliferation but also migration and stem-cell content. Therefore, modulation of p53/p21 activity in stromal fibs merits further investigation.