title: RNA sequencing supports distinct reactive oxygen species-mediated pathways of apoptosis by high and low size mass fractions of Bay leaf (Lauris nobilis) in HT-29 cells.
abstract: Anti-proliferative and pro-apoptotic effects of Bay leaf (Laurus nobilis) in mammalian cancer and HT-29 adenocarcinoma cells have been previously attributed to effects of polyphenolic and essential oil chemical species. Recently, we demonstrated differentiated growth-regulating effects of high (HFBL) versus low molecular mass (LFBL) aqueous fractions of bay leaf and now confirm by comparative effects on gene expression, that HFBL and LFBL suppress HT-29 growth by distinct mechanisms. Induction of intra-cellular lesions including DNA strand breakage by extra-cellular HFBL, invoked the hypothesis that iron-mediated reactive oxygen species with capacity to penetrate cell membrane, were responsible for HFBL-mediated effects, supported by equivalent effects of HFBL in combination with γ radiation. Activities of HFBL and LFBL were interpreted to reflect differentiated responses to iron-mediated reactive oxygen species (ROS), occurring either outside or inside cells. In the presence of LFBL, apoptotic death was relatively delayed compared with HFBL. ROS production by LFBL mediated p53-dependent apoptosis and recovery was suppressed by promoting G1/S phase arrest and failure of cellular tight junctions. In comparison, intra-cellular anti-oxidant protection exerted by LFBL was absent for extra-cellular HFBL (likely polysaccharide-rich), which potentiated more rapid apoptosis by producing DNA double strand breaks. Differentiated effects on expression of genes regulating ROS defense and chromatic condensation by LFBL versus HFBL, were observed. The results support ferrous iron in cell culture systems and potentially in vivo, can invoke different extra-cellular versus intra-cellular ROS-mediated chemistries, that may be regulated by exogenous, including dietary species.
authors.affiliation: Epigenomic Medicine, Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia.
authors.forename: Annabelle L
authors.initials: AL
authors.lastname: Rodd
authors.forename: Katherine
authors.initials: K
authors.lastname: Ververis
authors.forename: Dheeshana
authors.initials: D
authors.lastname: Sayakkarage
authors.forename: Abdul W
authors.initials: AW
authors.lastname: Khan
authors.forename: Haloom
authors.initials: H
authors.lastname: Rafehi
authors.forename: Mark
authors.initials: M
authors.lastname: Ziemann
authors.forename: Shanon J
authors.initials: SJ
authors.lastname: Loveridge
authors.forename: Ross
authors.initials: R
authors.lastname: Lazarus
authors.forename: Caroline
authors.initials: C
authors.lastname: Kerr
authors.forename: Trevor
authors.initials: T
authors.lastname: Lockett
authors.forename: Assam
authors.initials: A
authors.lastname: El-Osta
authors.forename: Tom C
authors.initials: TC
authors.lastname: Karagiannis
authors.forename: Louise E
authors.initials: LE
authors.lastname: Bennett
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D027442:Laurus / Q000737:chemistry*; D008970:Molecular Weight; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism*; D017423:Sequence Analysis, RNA
chemical_list: D010936:Plant Extracts; D017382:Reactive Oxygen Species