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
67P - The effect of non-viral gene-immune therapy via OX40L or 4-1BBL on murine subcutaneous CT26 colon cancer model
Presenter: Olga Rakitina
Session: Poster session 09
68P - Dendritic polylysine with paclitaxel and triptolide codelivery for enhanced NSCLC ferroptosis through the accumulation of ROS
Presenter: Huae Xu
Session: Poster session 09
69P - Novel monoclonal antibodies can distinguish Cripto-1 from Cripto-3 proteins: Clinical implications and potential new biomarkers
Presenter: Josune Garcia-Sanmartin
Session: Poster session 09
70P - The human intratumor mycobiome is significantly influenced by an individual's race
Presenter: Dan Coster
Session: Poster session 09
71P - Preclinical characterization of ARX305: A next-generation anti-CD70 antibody drug conjugate for the treatment of CD70-expressing cancers
Presenter: Lillian Skidmore
Session: Poster session 09
72P - Impact of extended panel of genes for germline cancer testing
Presenter: Shaheenah Dawood
Session: Poster session 09
73P - Preclinical and clinical presentation of the nerve-driven tumor spread
Presenter: Dawid Sigorski
Session: Poster session 09
74P - Characterization of ERBB2 variation and their association with immune response in solid tumours
Presenter: Dong Wang
Session: Poster session 09
75P - Double-stranded RNA transfection induced anti-tumour effect mediated by dual RIG-I and TLR-3 immune pathways
Presenter: Jiayu Tai
Session: Poster session 09
76P - Improvement of whole-cell cancer vaccine anti-tumor effect by different injection methods
Presenter: Chin yang Chang
Session: Poster session 09