title: TLR9 re-expression in cancer cells extends the S-phase and stabilizes p16(INK4a) protein expression.
abstract: Toll-like receptor 9 (TLR9) recognizes bacterial, viral or cell damage-associated DNA, which initiates innate immune responses. We have previously shown that TLR9 expression is downregulated in several viral induced cancers including HPV16-induced cervical neoplasia. Findings supported that downregulation of TLR9 expression is involved in loss of anti-viral innate immunity allowing an efficient viral replication. Here we investigated the role of TLR9 in altering the growth of transformed epithelial cells. Re-introducing TLR9 under the control of an exogenous promoter in cervical or head and neck cancer patient-derived cells reduced cell proliferation, colony formation and prevented independent growth of cells under soft agar. Neither TLR3, 7, nor the TLR adapter protein MyD88 expression had any effect on cell proliferation, indicating that TLR9 has a unique role in controlling cell growth. The reduction of cell growth was not due to apoptosis or necrosis, yet we observed that cells expressing TLR9 were slower in entering the S-phase of the cell cycle. Microarray-based gene expression profiling analysis highlighted a strong interferon (IFN) signature in TLR9-expressing head and neck cancer cells, with an increase in IFN-type I and IL-29 expression (IFN-type III), yet neither IFN-type I nor IL-29 production was responsible for the block in cell growth. We observed that the protein half-life of p16(INK4a) was increased in TLR9-expressing cells. Taken together, these data show for the first time that TLR9 affects the cell cycle by regulating p16(INK4a) post-translational modifications and highlights the role of TLR9 in the events that lead to carcinogenesis.
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: P
authors.initials: P
authors.lastname: Parroche
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: G
authors.initials: G
authors.lastname: Roblot
authors.affiliation: IARC-International Agency for Research on Cancer 150 Cours Albert Thomas, Lyon, France.
authors.forename: F
authors.initials: F
authors.lastname: Le Calvez-Kelm
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: I
authors.initials: I
authors.lastname: Tout
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: M
authors.initials: M
authors.lastname: Marotel
authors.affiliation: CRCL, UMR INSERM 1052-CNRS 5286, Centre Léon Bérard, Lyon France.
authors.forename: M
authors.initials: M
authors.lastname: Malfroy
authors.affiliation: IARC-International Agency for Research on Cancer 150 Cours Albert Thomas, Lyon, France.
authors.forename: G
authors.initials: G
authors.lastname: Durand
authors.affiliation: IARC-International Agency for Research on Cancer 150 Cours Albert Thomas, Lyon, France.
authors.forename: J
authors.initials: J
authors.lastname: McKay
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: M
authors.initials: M
authors.lastname: Ainouze
authors.affiliation: IARC-International Agency for Research on Cancer 150 Cours Albert Thomas, Lyon, France.
authors.forename: C
authors.initials: C
authors.lastname: Carreira
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: O
authors.initials: O
authors.lastname: Allatif
authors.affiliation: Hospices Civils Lyon Sud, Pierre Benite, France.
authors.forename: A
authors.initials: A
authors.lastname: Traverse-Glehen
authors.affiliation: Molecular Pathology and Therapeutic Targets Group, Research Insitute (IdiPAZ), La Paz University Hospital, Madrid, Spain and Molecular Pathology Diagnostics Unit, Institute of Medical and Molecular Genetics (INGEMM), La Paz University Hospital, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Mendiola
authors.affiliation: Pathology Department, La Paz University Hospital, Madrid Spain.
authors.forename: J J
authors.initials: JJ
authors.lastname: Pozo-Kreilinger
authors.affiliation: CRCL, UMR INSERM 1052-CNRS 5286, Centre Léon Bérard, Lyon France.
authors.forename: C
authors.initials: C
authors.lastname: Caux
authors.affiliation: IARC-International Agency for Research on Cancer 150 Cours Albert Thomas, Lyon, France.
authors.forename: M
authors.initials: M
authors.lastname: Tommasino
authors.affiliation: CRCL, UMR INSERM 1052-CNRS 5286, Centre Léon Bérard, Lyon France.
authors.forename: N
authors.initials: N
authors.lastname: Goutagny
authors.affiliation: CIRI, INSERM U1111, Ecole Normale Supérieure, Université de Lyon, Lyon, France.
authors.forename: U A
authors.initials: UA
authors.lastname: Hasan