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Updated: Mar 22, 2026
Detection of Heterodimerization of Protein Isoforms Using an in Situ Proximity Ligation Assay
Published on: October 20, 2018
Identification of cytotoxic agents disrupting synovial sarcoma oncoprotein interactions by proximity ligation assay
Aimée N Laporte1,2, Jennifer X Ji2, Limin Ma3
1Department of Pathology and Laboratory Medicine, Vancouver Coastal Health Research Institute and Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
Abstract:
Conventional cytotoxic therapies for synovial sarcoma provide limited benefit. Drugs specifically targeting the product of its driver translocation are currently unavailable, in part because the SS18-SSX oncoprotein functions via aberrant interactions within multiprotein complexes. Proximity ligation assay is a recently-developed method that assesses protein-protein interactions in situ. Here we report use of the proximity ligation assay to confirm the oncogenic association of SS18-SSX with its co-factor TLE1 in multiple human synovial sarcoma cell lines and in surgically-excised human tumor tissue. SS18-SSX/TLE1 interactions are disrupted by class I HDAC inhibitors and novel small molecule inhibitors. This assay can be applied in a high-throughput format for drug discovery in fusion-oncoprotein associated cancers where key effector partners are known.
Insights
Researchers confirmed the SS18-SSX oncoprotein
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Synovial sarcoma treatment options are limited, with conventional therapies offering minimal benefit.
- Targeted therapies for SS18-SSX oncoprotein are lacking due to its complex protein interactions.
- The SS18-SSX oncoprotein drives synovial sarcoma through aberrant interactions within multiprotein complexes.
Purpose of the Study:
- To confirm the oncogenic association of SS18-SSX with its co-factor TLE1 in synovial sarcoma.
- To investigate the disruption of SS18-SSX/TLE1 interactions using novel small molecule inhibitors and HDAC inhibitors.
- To evaluate the utility of proximity ligation assay for drug discovery in fusion-oncoprotein associated cancers.
Main Methods:
- Utilized proximity ligation assay (PLA) to assess SS18-SSX and TLE1 protein-protein interactions in situ.
- Confirmed interactions in human synovial sarcoma cell lines and surgically-excised tumor tissues.
- Tested the effect of class I HDAC inhibitors and novel small molecule inhibitors on SS18-SSX/TLE1 interactions.
Main Results:
- Proximity ligation assay confirmed the oncogenic SS18-SSX/TLE1 association in synovial sarcoma.
- SS18-SSX/TLE1 interactions were successfully disrupted by both class I HDAC inhibitors and novel small molecule inhibitors.
- The proximity ligation assay demonstrated potential for high-throughput drug screening.
Conclusions:
- The SS18-SSX oncoprotein's interaction with TLE1 is a validated target in synovial sarcoma.
- Small molecule inhibitors and HDAC inhibitors show promise in disrupting SS18-SSX/TLE1 interactions.
- Proximity ligation assay is a valuable tool for drug discovery in fusion-oncoprotein driven cancers.
