Abstract 4442: Wilms' tumor 1-associating protein increases cancer cell proliferation and stem-cell like properties through RNA modification

Abstract

Abstract Purpose: Wilms' tumor 1-associating protein (WTAP) which is known for its role in RNA methylation machinery, is highly upregulated in the necrotic region of glioblastoma multiforme (GBM). The highly heterogenic nature of GBM is associated with the necrotic region within the brain, where many types of cells such as the stromal cell, immune cells, and cancer stem cells co-localize. The complex cellular network within the necrotic region is believed to cause the resistance of the conventional chemotherapy and radiotherapy. Here we attempted to identify the role of WTAP in GBM and what kind of RNA modification is associated with the proliferation and stemness in GBM. Improvement of our understanding about post-transcriptional regulation in GBM will allow us to find out the key oncogenic switch in GBM, and development of therapeutics targeting this mechanism will provide better survival benefits. Methods: 23 Patient-derived cell lines, two established GBM cell lines, and astrocyte was arrayed to find out the correlation between WTAP and cancer stem cells. shWTAP and WTAP overexpression vector were infected into patient-derived GBM cancer stem cell lines to test the effect of WTAP. Western blot and polymerase chain reaction analysis was performed to find out the change in genes which are related to cell proliferation and stemness. Limiting dilution assay was performed to validate the function of WTAP in sphere-forming ability. RNA sequencing was performed on shWTAP infected patient-derived cancer stem cell to identify the type of RNA modification made by knocking down WTAP. Results: Knocking down of WTAP using shWTAP in patient-derived cancer stem cell lines, we were able to see the decrease in cell proliferation and stemness-related genes while overexpressing WTAP in these cells slightly increased cell proliferation and stemness. WTAP knockdown cells had a significant decrease in sphere-forming ability. RNA sequencing of shWTAP cells has revealed the increase in intron retention and the decrease in exon skipping, which shows that WTAP has a role in decreasing intron retention while increasing exon skipping. Conclusion: We have revealed that WTAP has an important role in increasing proliferation and maintaining stemness in GBM. We have also identified that WTAP decreases intron retention and increasing exon skipping. Citation Format: Sae Whan Park, Young Taek Oh, Jong Bae Park, Jong Heon Kim. Wilms' tumor 1-associating protein increases cancer cell proliferation and stem-cell like properties through RNA modification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4442.