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Published on: November 9, 2020
Genomic profiling in CEPH cell lines distinguishes between the camptothecins and indenoisoquinolines
Venita Gresham Watson1, Nicholas E Hardison, Tyndall Harris
1UNC Institute for Pharmacogenomics and Individualized Therapy, Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Abstract:
We have attempted to use a familial genetics strategy to study mechanisms of topoisomerase 1 (Top1) inhibition. Investigations have steadily been chipping away at the pathways involved in cellular response following Top1 inhibition for more than 20 years. Our system-wide approach, which phenotypes a collection of genotyped human cell lines for sensitivity to compounds and interrogates all genes and molecular pathways simultaneously. Previously, we characterized the in vitro sensitivity of 15 families of Centre d'Etude Polymorphisme Humain (CEPH) cell lines (n = 142) to 9 camptothecin analogues. Linkage analysis revealed a pattern of 7 quantitative trait loci (QTL) shared by all of the camptothecins. To identify which, if any, QTLs are related to the general mechanism of Top1 inhibition or should be considered camptothecin specific, we characterized the in vitro sensitivity of the same panel of CEPH cell lines to the indenisoquinolones, a structurally distinct class of Top1 inhibitors. Four QTLs on chromosomes 1, 5, 11, and 16 were shared by both the camptothecins and the indenoisoquinolines and are considered associated with the general mechanism of Top1 inhibition. The remaining 3 QTLs (chromosomes 6 and 20) are considered specific to camptothecin-induced cytotoxicity. Finally, 8 QTLs were identified, which were unique to the indenoisoquinolines.
Insights
Familial genetics identified quantitative trait loci (QTLs) for topoisomerase 1 (Top1) inhibition. Four QTLs are linked to general Top1 inhibition, while others are specific to camptothecin or indenoisoquinoline drugs.
Area of Science:
- Genetics
- Pharmacology
- Molecular Biology
Background:
- Topoisomerase 1 (Top1) inhibitors are crucial in cancer therapy.
- Understanding cellular responses to Top1 inhibition is vital for drug development.
- Familial genetics offers a powerful approach to dissecting complex biological mechanisms.
Purpose of the Study:
- To differentiate between general Top1 inhibition mechanisms and drug-specific effects using a familial genetics strategy.
- To identify quantitative trait loci (QTLs) associated with sensitivity to different classes of Top1 inhibitors.
- To leverage a system-wide approach for comprehensive pathway interrogation.
Main Methods:
- Phenotyped genotyped human cell lines (CEPH families) for sensitivity to camptothecins and indenoisoquinolines.
- Performed linkage analysis to identify QTLs associated with drug sensitivity.
- Compared QTLs identified for structurally distinct Top1 inhibitors to determine shared and unique genetic factors.
Main Results:
- Identified 7 QTLs shared by all camptothecins.
- Discovered 4 QTLs common to both camptothecins and indenoisoquinolines, indicating general Top1 inhibition mechanisms.
- Found 3 QTLs specific to camptothecin cytotoxicity and 8 QTLs unique to indenoisoquinolines.
Conclusions:
- Established a genetic basis for differential sensitivity to Top1 inhibitors.
- Differentiated general Top1 inhibition pathways from drug-specific responses.
- Provided insights into the genetic architecture of cellular responses to Top1-targeted therapies.
