Gene expression profiling of tumor stroma interactions in retinoblastoma
EXPERIMENTAL EYE RESEARCH
Authors: Raguraman, Rajeswari; Parameswaran, Sowmya; Kanwar, Jagat Rakesh; Vasudevan, Madavan; Chitipothu, Srujana; Kanwar, Rupinder Kaur; Krishnakumar, Subramanian
Abstract
We aimed to identify the critical molecular pathways altered upon tumor stroma interactions in retinoblastoma (RB). In vitro 2 D cocultures of RB tumor cells (Weri-Rb-1 and NCC-RbC-51) with primary bone marrow stromal cells (BMSC) was established. Global gene expression patterns in coculture samples were assessed using Affymetrix Prime view human gene chip microarray and followed with bioinformatics analyses. Key upregulated genes from Weri-Rb-1 + BMSC and NCC-RbC-51 + BMSC coculture were validated using qRT-PCR to ascertain their role in RB progression. Whole genome microarray experiments identified significant (P <= 0.05, 1.1 log 2 FC) transcriptome level changes induced upon coculture of RB cells with BMSC. A total of 1155 genes were downregulated and 1083 upregulated in Weri-Rb-1 + BMSC coculture. Similarly, 1865 genes showed down regulation and 1644 genes were upregulation in NCC-RbC-51 + BMSC coculture. The upregulated genes were significantly associated with pathways of focal adhesion, PI3K-Akt signalling, ECM-receptor interaction, JAKSTAT, TGF-beta signalling thus contributing to RB progression. Validation of key genes by qRT-PCR revealed significant overexpression of IL8, IL6, MYC and SMAD3 in the case of Weri-Rb-1 + BMSC coculture and IL6 in the case of NCC-RbC-51 + BMSC coculture. The microarray expression study on in vitro RB coculture models revealed the pathways that could be involved in the progression of RB. The gene signature obtained in a stimulated model when a growing tumor interacts with its microenvironment may provide new horizons for potential targeted therapy in RB.
Cross-tolerance: embryonic heat conditioning induces inflammatory resilience by affecting different layers of epigenetic mechanisms regulatingIL6expression later in life
EPIGENETICS
Authors: Rosenberg, Tali; Kisliouk, Tatiana; Ben-Nun, Osher; Cramer, Tomer; Meiri, Noam
Abstract
A stressor can induce resilience in another, different stressor, a phenomenon known as cross-tolerance. To learn if cross-tolerance is governed by epigenetic regulation, we used embryonic heat conditioning (EHC) in chicks, during the development of the hypothalamus, to increase the immunization response. Indeed, EHC induced a lifelong systemic antibody response to immunization, in addition to reduced hypothalamicIL6inflammatory expression following LPS challenge. Since the outcome of EHC was long-term cross-tolerance with the immune system, we studied possible epigenetic mechanisms. We first analysed the methylation and hydroxymethylation patterns ofIL6. We found reduced hydroxymethylation onIL6intron 1 in the EHC group, a segment enriched with CpGs and NFkB-binding sites. Luciferase assay in cell lines expressing NFkB showed thatIL6intron 1 is indeed an enhancer. ChiP in the same segment against NFkB in the hypothalamus presented reduced binding toIL6intron 1 in the EHC group, before and during LPS challenge. In parallel, EHC chicks'IL6intron 1 presented increased H3K27me3, a repressive translational modification mediated by EZH2. This histone modification occurred during embryonic conditioning and persisted later in life. Moreover, we showed reduced expression of miR-26a, which inhibitsEZH2transcription, during conditioning along with increasedEZH2expression. We demonstrate that stress cross-tolerance, which was indicated by EHC-induced inflammatory resilience and displayed by attenuated inflammatory expression ofIL6, is regulated by different epigenetic layers.