Repression of the SUMO-conjugating enzyme UBC9 is associated with lowered double minutes and reduced tumor
Yusi Wang1,2, Hongyan Zou1,2, Wei Ji1,2
1Laboratory of Medical Genetics, Harbin Medical University, Harbin, China.
Abstract:
Double minutes (DMs), extrachromosomal gene fragments found within certain tumors, have been noted to carry onco- and drug resistance genes contributing to tumor pathogenesis and progression. After screening for SUMO-related molecule expression within various tumor sample and cell line databases, we found that SUMO-conjugating enzyme UBC9 has been associated with genome instability and tumor cell DM counts, which was confirmed both in vitro and in vivo. Karyotyping determined DM counts post-UBC9 knockdown or SUMOylation inhibitor 2-D08, while RT-qPCR and Western blot were used to measure DM-carried gene expression in vitro. In vivo, fluorescence in situ hybridization (FISH) identified micronucleus (MN) expulsion. Western blot and immunofluorescence staining were then used to determine DNA damage extent, and a reporter plasmid system was constructed to detect changes in homologous recombination (HR) and non-homologous end joining (NHEJ) pathways. Our research has shown that UBC9 inhibition is able to attenuate DM formation and lower DM-carried gene expression, in turn reducing tumor growth and malignant phenotype, via MN efflux of DMs and lowering NHEJ activity to increase DNA damage. These findings thus reveal a relationship between heightened UBC9 activity, increased DM counts, and tumor progression, providing a potential approach for targeted therapies, via UBC9 inhibition.
Insights
Inhibiting the SUMO-conjugating enzyme UBC9 reduces double minutes (DMs) and associated gene expression, thereby decreasing tumor growth and malignancy. This targeted approach offers a new strategy for cancer therapy.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Double minutes (DMs) are extrachromosomal DNA fragments in tumors carrying oncogenes and drug resistance genes.
- Increased DMs correlate with tumor progression and poor prognosis.
- SUMOylation pathway enzymes, including UBC9, are implicated in genome instability.
Purpose of the Study:
- To investigate the role of SUMO-conjugating enzyme UBC9 in the formation of double minutes (DMs) in tumor cells.
- To determine if inhibiting UBC9 can reduce DM formation and impact tumor progression.
- To explore the therapeutic potential of targeting UBC9 for cancer treatment.
Main Methods:
- Screening tumor databases for SUMO-related molecule expression.
- In vitro and in vivo experiments involving UBC9 knockdown and SUMOylation inhibitor treatment.
- Karyotyping, RT-qPCR, Western blot, fluorescence in situ hybridization (FISH), and reporter plasmid assays were used to assess DM counts, gene expression, DNA damage, and DNA repair pathways (HR and NHEJ).
Main Results:
- UBC9 expression is associated with genome instability and DM counts in tumor cells.
- Inhibition of UBC9 significantly attenuated DM formation and reduced the expression of DM-carried genes.
- UBC9 inhibition led to reduced tumor growth and malignant phenotype, mediated by micronucleus expulsion of DMs and increased DNA damage via reduced NHEJ activity.
Conclusions:
- Heightened UBC9 activity is linked to increased DM formation and tumor progression.
- Targeting UBC9 can effectively reduce DM formation and suppress tumor growth.
- UBC9 inhibition represents a promising therapeutic strategy for cancers characterized by double minutes.
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