Cytoskeletal filamin A (FLNA) modulates numerous cellular processes including cell signaling, cell migration and invasion, cell proliferation, transcription and etc.Mutations of FLNA cause a range of congenital genetic diseases;FLNA has been described to promote or inhibit cancer cell growth and metastasis depending on particular circumstance.However, the mechanism underlying the events remains elusive.Previous work showed that FLNA is a nucleolar protein and represses ribosomal RNA gene transcription and cell proliferation.Since FLNA inhibits the synthesis of RNA polymerase Ⅰ (pol Ⅰ) product including 5.8S, 18S and 28S ribosomal RNA;whereas another important component of ribosome, 5S rRNA, is synthesized by RNA polymerase Ⅲ (pol Ⅲ).Thus,we supposed that FLNA could also represses RNA pol Ⅲ gene transcription in order to co-ordinate synthesis of ribosome in cell.In this study, we identified a novel role for FLNA that represses RNA pol Ⅲ gene transcription by altering expression level of FLNA in cells.We show that FLNA associates with RNA polymerase Ⅲ gene transcription machinery and inhibits RNA pol Ⅲ gene transcription by impeding expression of TFⅢB and TFⅢC and their recruitments to the promoters of several detected pol Ⅲ-transcribed genes.It suggests that FLNA modulates RNA pol Ⅲ gene transcription by employing a distinctive mechanism from that it does RNA pol Ⅰ gene transcription.Our findings provide a novel insight into the mechanism by which FLNA represses cancer cell proliferation.