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The deubiquitinating enzyme USP5 promotes pancreatic cancer via modulating cell cycle regulators
Brajesh P Kaistha1, Anja Krattenmacher1, Johannes Fredebohm2
1Department of Medicine, Division of Gastroenterology, Endocrinology and Metabolism, Philipps-University Marburg, Marburg, Germany.
Abstract:
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal solid tumors. With an overall five-year survival rate remaining below 6%, there is an explicit need to search for new molecular targets for therapeutic interventions. We undertook a barcode labelled short-hairpin (shRNA) library screen in pancreatic cancer cells in order to identify novel genes promoting cancer survival and progression. Among the candidate genes identified in this screen was the deubiquitinase USP5, which subsequent gene expression analyses demonstrated to be significantly upregulated in primary human pancreatic cancer tissues. Using different knockdown approaches, we show that expression of USP5 is essential for the proliferation and survival of pancreatic cancer cells, tested under different 2D and 3D cell culture conditions as well as in in vivo experiments. These growth inhibition effects upon knockdown of USP5 are mediated primarily by the attenuation of G1/S phase transition in the cells, which is accompanied by accumulation of DNA damage, upregulation of p27, and increased apoptosis rates. Since USP5 is overexpressed in cancer tissues, it can thus potentially serve as a new target for therapeutic interventions, especially given the fact that deubiquitinases are currently emerging as new class of attractive drug targets in cancer.
Insights
Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer. Researchers identified USP5 as crucial for PDAC cell survival and proliferation, suggesting it as a potential therapeutic target.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Pancreatic ductal adenocarcinoma (PDAC) has a very low survival rate, necessitating new therapeutic targets.
- Deubiquitinases are emerging as promising drug targets in cancer therapy.
Purpose of the Study:
- To identify novel genes involved in pancreatic cancer survival and progression using a functional genomics screen.
- To investigate the role of the deubiquitinase USP5 in PDAC.
Main Methods:
- A short-hairpin RNA (shRNA) library screen was performed in pancreatic cancer cells.
- Gene expression analysis in human pancreatic cancer tissues.
- Knockdown experiments in cell culture (2D and 3D) and in vivo models.
- Cell cycle analysis, DNA damage assessment, and apoptosis assays.
Main Results:
- USP5 was identified as a candidate gene in the shRNA screen and found to be upregulated in human PDAC tissues.
- Knockdown of USP5 inhibited pancreatic cancer cell proliferation and survival.
- USP5 knockdown led to G1/S phase cell cycle arrest, DNA damage accumulation, p27 upregulation, and increased apoptosis.
Conclusions:
- USP5 is essential for pancreatic cancer cell proliferation and survival.
- USP5 represents a potential novel therapeutic target for pancreatic ductal adenocarcinoma.