DIPG-01. LIN28B EXPRESSION IN DIFFUSE MIDLINE GLIOMA

Diffuse midline glioma (DMG) is the most lethal of all childhood cancers. LIN28B is an RNA binding protein expressed in a variety of cancers, which suppresses the let-7 family of microRNAs, which in turn suppresses a plethora of oncogenes. However, the role of LIN28B in DMG has not yet been explored. Therefore, we sought to determine the pattern of expression and potential function of LIN28B in DMG using rare DMG cell lines.

All studies were performed on DMG cell lines (n=6) and controls (normal human astrocytes n=1, human neural stem cells n=1). RNA-Seq was performed using single-read sequencing at 50bp on the Illumina NextSeq 500 Sequencing System. Cells were then treated with DMSO or the LIN28B inhibitor, LI71, and submitted to functional in vitro studies, as well as RNA-Seq and Western Blot analysis. Functional pathways analysis was subsequently performed on resulting gene expression values with Ingenuity Pathways Analysis (Qiagen).

Differential LIN28B expression was demonstrated across cell lines, with DMG cells expressing greater LIN28B gene and protein levels compared to controls. LIN28B inhibition with small molecule inhibitor LI71 resulted in decreased cell proliferation and migration, in vitro. A total of 946 differentially expressed genes were identified between treatment groups (FC>2 or <-2, p<0.05). Functional pathways analysis of differentially expressed genes implicated Cancer and Neurological Disease as the top disease processes, with Cellular Movement as the top molecular process in cell lines expressing LIN28B. Further, inactivation of Myc signaling was implicated in cells treated with LI71.

Our data demonstrates increased LIN28B expression in DMG cell lines compared with controls, with oncogenic effects on cell proliferation and migration. Further investigation of the LIN28B-let7 signaling axis is warranted in order to further explore LIN28B as a novel therapeutic target in DMG.