title: Stress-response protein RBM3 attenuates the stem-like properties of prostate cancer cells by interfering with CD44 variant splicing.
abstract: Stress-response pathways play an important role in cancer. The cold-inducible RNA-binding protein RBM3 is upregulated in several types of cancer, including prostate cancer, but its pathogenic contributions are undetermined. RBM3 is expressed at low basal levels in human fetal prostate or in CD133(+) prostate epithelial cells (PrEC), compared with the adult prostate or CD133-PrEC, and RBM3 is downregulated in cells cultured in soft agar or exposed to stress. Notably, RBM3 overexpression in prostate cancer cells attenuated their stem cell-like properties in vitro as well as their tumorigenic potential in vivo. Interestingly, either overexpressing RBM3 or culturing cells at 32°C suppressed RNA splicing of the CD44 variant v8-v10 and increased expression of the standard CD44 (CD44s) isoform. Conversely, silencing RBM3 or culturing cells in soft agar (under conditions that enrich for stem cell-like cells) increased the ratio of CD44v8-v10 to CD44s mRNA. Mechanistic investigations showed that elevating CD44v8-v10 interfered with MMP9-mediated cleavage of CD44s and suppressed expression of cyclin D1, whereas siRNA-mediated silencing of CD44v8-v10 impaired the ability of prostate cancer cells to form colonies in soft agar. Together, these findings suggested that RBM3 contributed to stem cell-like character in prostate cancer by inhibiting CD44v8-v10 splicing. Our work uncovers a hitherto unappreciated role of RBM3 in linking stress-regulated RNA splicing to tumorigenesis, with potential prognostic and therapeutic implications in prostate cancer.
authors.affiliation: The James Buchanan Brady Urological Institute, Baltimore, Maryland, USA zengyud@hotmail.com
authors.forename: Yu
authors.initials: Y
authors.lastname: Zeng
authors.forename: Dana
authors.initials: D
authors.lastname: Wodzenski
authors.forename: Dong
authors.initials: D
authors.lastname: Gao
authors.forename: Takumi
authors.initials: T
authors.lastname: Shiraishi
authors.forename: Naoki
authors.initials: N
authors.lastname: Terada
authors.forename: Youqiang
authors.initials: Y
authors.lastname: Li
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Vander Griend
authors.forename: Jun
authors.initials: J
authors.lastname: Luo
authors.forename: Chuize
authors.initials: C
authors.lastname: Kong
authors.forename: Robert H
authors.initials: RH
authors.lastname: Getzenberg
authors.forename: Prakash
authors.initials: P
authors.lastname: Kulkarni
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D005091:Exons; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000502:physiology*; D011467:Prostate / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D016601:RNA-Binding Proteins / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological; D014407:Tumor Cells, Cultured
chemical_list: C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D020033:Protein Isoforms; C099506:RBM3 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins