Androgen-Induced Cell Migration: Role of Androgen Receptor/Filamin A Association

Abstract

BackgroundAndrogen receptor (AR) controls male morphogenesis, gametogenesis and prostate growth as well as development of prostate cancer. These findings support a role for AR in cell migration and invasiveness. However, the molecular mechanism involved in AR-mediated cell migration still remains elusive.Methodology/Principal FindingsMouse embryo NIH3T3 fibroblasts and highly metastatic human fibrosarcoma HT1080 cells harbor low levels of transcriptionally incompetent AR. We now report that, through extra nuclear action, AR triggers migration of both cell types upon stimulation with physiological concentrations of the androgen R1881. We analyzed the initial events leading to androgen-induced cell migration and observed that challenging NIH3T3 cells with 10 nM R1881 rapidly induces interaction of AR with filamin A (FlnA) at cytoskeleton. AR/FlnA complex recruits integrin beta 1, thus activating its dependent cascade. Silencing of AR, FlnA and integrin beta 1 shows that this ternary complex controls focal adhesion kinase (FAK), paxillin and Rac, thereby driving cell migration. FAK-null fibroblasts migrate poorly and Rac inhibition by EHT impairs motility of androgen-treated NIH3T3 cells. Interestingly, FAK and Rac activation by androgens are independent of each other. Findings in human fibrosarcoma HT1080 cells strengthen the role of Rac in androgen signaling. The Rac inhibitor significantly impairs androgen-induced migration in these cells. A mutant AR, deleted of the sequence interacting with FlnA, fails to mediate FAK activation and paxillin tyrosine phosphorylation in androgen-stimulated cells, further reinforcing the role of AR/FlnA interaction in androgen-mediated motility.Conclusions/SignificanceThe present report, for the first time, indicates that the extra nuclear AR/FlnA/integrin beta 1 complex is the key by which androgen activates signaling leading to cell migration. Assembly of this ternary complex may control organ development and prostate cancer metastasis.

Non-Genomic Actions of the Androgen Receptor in Prostate Cancer

“…These findings suggest that inhibitory effects on proliferation at high androgen levels come from a loss of transient AR protein–protein interactions with Src upon saturation of AR with ligand, rather than a diversion of AR to perform genomic functions. In NIH3T3 fibroblast cells, exposure to optimal concentration of androgen (10 nM) suppresses cell cycle progression, induces interactions between AR with the cytoskeletal protein Filamin A, and recruits integrin beta 1 to coordinate cell migration by activating focal adhesion kinase, paxillin, and Rac (25, 26). In malignant prostate tissue, cytoplasmic localization of Filamin A correlates with metastatic potential and an androgen-independent phenotype (27).…”

The actin cross-linker Filamin/Cheerio mediates tumor malignancy downstream of JNK signaling

“…The role of FLNA in tumorigenesis remains controversial. Although downregulation of FLNA expression increases the invasiveness of human breast cancer cells (Cunningham et al, 1992;Xu et al, 2010), a positive effect of FLNA on cell migration has also been reported (Castoria et al, 2011;Cunningham et al, 1992). FLNA expression levels in tumors and plasma of patients with breast and primary brain tumors increase with tumor malignancy (Ai et al, 2011;Alper et al, 2009;Bedolla et al, 2009).…”

Nonsteroidal Androgen Receptor Ligands: Versatile Syntheses and Biological Data

“…AR was detected by Western blot analysis, and the luciferase activity in cell lysates was measured and expressed as fold induction. 25 Figure 4 shows that 10 nM R1881 increases by 4.2-fold the AR-mediated transcriptional activity in LNCaP cells. Expectedly, the antiandrogen Casodex (at 10 μM) inhibits such an activation.…”