Abstract 87P
Background
Wip1/PPM1D is a serin/threonine phosphatase which is involved in timely termination of DNA damage response. Overexpression of Wip1 is commonly seen in human solid cancers including neuroblastoma and medulloblastoma that displays oncogenic features. Oncogenic Wip1 negatively regulates tumor suppressor responses such as apoptosis or senescence. Autophagy plays a tumor suppressor role by removing damaged organelles/proteins and limiting cell growth and genomic instability in cancer cells. The molecular mechanisms underlying autophagy's tumor-promoting activities are largely unknown Here, we investigated the role of oncogenic Wip1 phospahates in regulation of autophagy in neuroblastoma and medulloblastoma.
Methods
D283-med and IMR32 cells are grown according to ATTC protocol. Autophagy was stimulated with etoposide and inhibited with chloroquine. GSK2830371 is used to target Wip1. Autophagy markers are tested with WB analysis and with confocal microscopy analysis of LC3 I/II puncta formation. Vacuolazion was measured by quinacrine staining. Wip1-Ulk1 interaction was investigated via co-IP and co-localization analysis. BrDU/PI and Annexin V/7AAD assays were used to examine the cell cycle and apoptosis, respectively.
Results
In neuroblastoma and medulloblastoma cells, oncogenic Wip1 promotes etoposid induced autophagy and improves cancer cell survival. Wip1 phosphatase interacts with and dephosphorylates Ulk1 during etoposide induced autophagy which is associated with elevated p53 levels. Suppression of Wip1 and/or autophagy prevents degredation of pro-apoptotic proteins thus results in promotion of apoptosis. Furthermore, inhibition of Wip1 and autophagy reduce cancer cells ability to colonize in vitro.
Conclusions
Oncogenic Wip1 play a key role in enhancing etoposide induced autophagy by dephosphorylating ULK1 and contributes to cancer cell survival. Wip1 mediated autophagy may be a promising therapeutic target for improvment of chemotherapy response.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
TUBITAK.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
14P - Peripheral immune kinetics in survival prediction of small cell lung cancer patients treated with immune checkpoint blockade therapy
Presenter: MIGUEL GALINDO CAMPOS
Session: Poster session 09
15P - CBL E3 ubiquitin ligases are key inhibitory regulators in PD-1/LAG-3 co-signaling in human cancers, targeted through bispecific co-blockade
Presenter: Luisa Chocarro
Session: Poster session 09
16P - Terminally exhausted CD8+ T cells and increased immunosuppressive soluble factors in malignant ascites of patients with gastric cancer with peritoneal metastasis
Presenter: Hye Sook Han
Session: Poster session 09
17P - Continued expansion of long-lived effect CD8+ T cells associates with durable response post-PD-1 blockade
Presenter: Robert Watson
Session: Poster session 09
18P - Exposure of calreticulin is required for vitamin C immunomediated cancer surveillance
Presenter: Alessandro Cavaliere
Session: Poster session 09
19P - Preclinical and clinical significance of VEGF deprivation in ovarian cancer through a specific active immunotherapy
Presenter: Yanelys Morera
Session: Poster session 09
20P - The essential role of DNA repair in the pharmacological activities of AST-3424
Presenter: Fanying Meng
Session: Poster session 09
21P - Implications of KMT2C knockdown for DNA damage repair in breast cancer
Presenter: Philip Bredin
Session: Poster session 09
22P - Clinical significance of DNA damage response mutations in early stage NSCLC
Presenter: Haoran Zhang
Session: Poster session 09
23P - PMC-309: A highly selective anti-VISTA antibody reverses immunosuppressive TME to immune-supportive
Presenter: Cheon Ho Park
Session: Poster session 09