Abstract P4-05-17: ESR1 related chromothripsis enhances concordant gene transcription on chromosome 17q11.1-q24.1 in luminal breast cancer

• Published in: Cancer research (Chicago, Ill.) Vol. 80; no. 4_Supplement; pp. P4 - P4-05-17
• Main Author: Lin, Chun-Lin
• Format: Journal Article
• Language: English
• Published: 15.02.2020
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS19-P4-05-17

Abstract Chromothripsis is an event of genomic instability leading to complex chromosomal alterations in cancer. Although studies have proposed models to explain its initiation, few discussed how transcription factors (TFs) influence chromothripsis for tumor progression. Frequent long-range chromatin interactions between TFs and targets may promote extensive translocations and copy-number alterations in proximal contact regions through inappropriate DNA stitching. Herein we surveyed genomic alterations of chromosome 17 in 1,014 breast tumors in the Cancer Genome Atlas (TCGA) cohort and found five adjoining regions from 17q11.1 to 17q24.1 being hotspots of chromothripsis. Inter-/intra-chromosomal rearrangements of these regions occurred more frequently in ERα-positive tumors than in ERα-negative tumors. In addition, the rearrangement sites were often mapped within or close to dense estrogen receptor 1 (ESR1) sites localized on the regions or other chromosomes. This chromothriptic event was linked to concordant upregulation of 96 loci that predominantly regulate cell-cycle machineries in advanced luminal tumors. Genome-editing analysis confirmed that an ESR1 transcription hub localized on 20q13 coordinately regulates a subset of these loci localized on 17q23 through long-range chromosome interactions. One of these loci, Tousled Like Kinase 2 (TLK2) known to participate in DNA damage checkpoint control, is an actionable target using phenothiazine antipsychotics (PTZs). The antiproliferative effect of PTZs was prominent in high TLK2-expressing cells, compared to low expressing cells. Collectively, we identified a group of luminal breast tumors displaying 17q-related chromothripsis for which antipsychotics can be repurposed as treatment adjuncts. Citation Format: Chun-Lin Lin. ESR1 related chromothripsis enhances concordant gene transcription on chromosome 17q11.1-q24.1 in luminal breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-05-17.