Abstract 877: Novel role of truncated HMGA2 in regulating reactive oxygen species in prostate cancer cells

High mobility group A (HMGA2), a non-histone protein, is up-regulated in several cancers. Due to chromosomal rearrangement of HMGA2 gene, full-length or wild-type HMGA2 can be truncated leading to loss of the C-terminus and the 3’UTR. Both wild-type and truncated isoforms have been detected in uterine leiomyoma patients. However, the functional role of truncated HMGA2 has not been investigated. We hypothesize that truncated HMGA2 plays a role in prostate cancer progression. We analysed expression of wild-type vs truncated HMGA2 in a panel of prostate cancer cell lines using real-time PCR and western blot analyses. We utilized LNCaP cells stably overexpressing wild-type HMGA2 or truncated HMGA2 in LNCaP cells to detect the basal reactive oxygen species (ROS) levels using DCFDA dye. We analysed Jun-D expression, a putative downstream effector of HMGA2, by western blot analysis, and utilized siRNA to knockdown Jun-D. We performed migration and cell viability assays following Jun-D knockdown. Additionally, we performed proteomic analysis following immunoprecipitation with HMGA2 antibody in nuclear extracts from LNCaP cells overexpressing wild-type HMGA2 WT or cytoplasmic extracts from cells overexpressing truncated HMGA2. Finally, we utilized tissue microarray to analyse expression of HMGA2 by immunohistochemisty. Our results showed that prostate cancer cell lines expressed varying amounts of wild-type and truncated HMGA2. LNCaP cells overexpressing truncated HMGA2 exhibited increased nuclear expression of Jun-D, as well as increased ROS compared to LNCaP cells overexpressing wild-type HMGA2 or empty vector Neo control. Knockdown Jun-D in LNCaP cells overexpressing truncated HMGA2 abrogated ROS induction and cell migration with no effect on cell proliferation. Additionally, truncated HMGA2 interacted with a number of proteins, including Ras GTPase-activating protein-binding protein 1(G3BP1), a cytoplasmic stress granule protein that responds to oxidative stress. Truncated HMGA2 is mainly localized to the cytoplasm, and interestingly we also observed cytoplasmic HMGA expression in prostatic tissue with chronic inflammation. Therefore, truncated HMGA2 may promote prostate cancer progression via Jun-D-mediated ROS. GRANT SUPPORT: NIH 1P20MD002285 and NIH/NCRR/RCMI G12RR003062-22 Citation Format: Ohuod Hawsawi, Veronica Henderson, Liza Burton, Jodi Dougan, Ana Cecillia Millena, Vanessa Adams, Elshaddai Z. White, Guang Di Wang, Qiang Zhang, Cimona Hinton, Shafiq Khan, Valerie Odero-Marah. Novel role of truncated HMGA2 in regulating reactive oxygen species in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 877.