Downregulation of Human DAB2IP Gene Expression in Renal Cell Carcinoma Results in Resistance to Ionizing Radiation.

Abstract

PURPOSE:

Renal cell carcinoma (RCC) is known to be highly radioresistant but the mechanisms associated with radioresistance have remained elusive. We found DOC-2/DAB2 interactive protein (DAB2IP) frequently downregulated in RCC, is associated with radioresistance. In this study, we investigated the underlying mechanism regulating radioresistance by DAB2IP and developed appropriate treatment.

EXPERIMENTAL DESIGN:

Several RCC lines with or without DAB2IP expression were irradiated with ionizing radiation (IR) for determining their radiosensitivities based on colony formation assay. To investigate the underlying regulatory mechanism of DAB2IP, immunoprecipitation-mass spectrometry was performed to identify DAB2IP-interactive proteins. PARP-1 expression and enzymatic activity were determined using qRT-PCR, Western blot analysis, and ELISA. In vivo ubiquitination assay was used to test PARP-1 degradation. Furthermore, in vivo mice xenograft model and patient-derived xenograft (PDX) model were used to determine the effect of combination therapy to sensitizing tumors to IR.

RESULTS:

We notice that DAB2IP-deficient RCC cells acquire IR-resistance. Mechanistically, DAB2IP can form a complex with PARP-1 and E3 ligases that is responsible for degrading PARP-1. Indeed, elevated PARP-1 levels are associated with the IR resistance in RCC cells. Furthermore, PARP-1 inhibitor can enhance the IR response of either RCC xenograft model or PDX model.

CONCLUSIONS:

In this study, we unveil that loss of DAB2IP resulted in elevated PARP-1 protein is associated with IR-resistance in RCC. These results provide a new targeting strategy to improve the efficacy of radiotherapy of RCC.

• Authors: Eun-Jin Yun, Chun-Jung Lin, Andrew Dang, Elizabeth Hernandez, Jiaming Guo, Wei-Min Chen, Joyce Allison, Nathan Kim, Payal Kapur, James Brugarolas, Kaijie Wu, Dalin He, Chih-Ho Lai, Ho Lin, Debabrata Saha, Seung Tae Baek, Benjamin P C Chen, Jer-Tsong Hsieh
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 25 Issue 14 Pg. 4542-4551 (07 15 2019) ISSN: 1557-3265 [Electronic] United States
• PMID: 31000589 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: ©2019 American Association for Cancer Research.

Chemical References

• DAB2IP protein, human
• ras GTPase-Activating Proteins

Topics

• Animals
• Apoptosis
• Carcinoma, Renal Cell (drug therapy, genetics, pathology)
• Cell Proliferation
• Down-Regulation
• Female
• Gene Expression Regulation, Neoplastic (radiation effects)
• Humans
• Kidney Neoplasms (drug therapy, genetics, pathology)
• Mice
• Mice, Inbred NOD
• Mice, SCID
• Radiation Tolerance (genetics)
• Radiation, Ionizing
• Signal Transduction
• Tumor Cells, Cultured
• Xenograft Model Antitumor Assays
• ras GTPase-Activating Proteins (antagonists & inhibitors, genetics)