Analysis of DNA repair-related genes in breast cancer reveals CUL4A ubiquitin ligase as a novel biomarker of trabectedin response.
Trabectedin is more active in nucleotide excision repair (NER)-efficient and homologous recombination repair (HRR)-deficient cells. As up to 25% of sporadic breast tumors present somatic inactivation of the HRR pathway (BRCAness phenotype), we sought to characterize trabectedin effect in BRCA1-proficient and BRCA1-null breast cancer cell lines. We evaluated whether HRR and NER gene expression correlates with trabectedin sensitivity and explored the response predictive value of the CUL4A ubiquitin ligase, which ubiquitinates NER pathway members. We characterized trabectedin cytotoxicity, cell-cycle effects, and BRCA1, BRCA2, XRCC3, XPG, ERCC1, and CUL4A expression in 10 breast cancer cell lines. Gene expression and trabectedin sensitivity association were determined in cell lines. Survival assays after trabectedin treatment were conducted in CUL4A-silenced BRCA1-proficient and -deficient cells. Because of limited phase II clinical trials evaluating trabectedin efficacy in patients with breast cancer, we assessed CUL4A immunohistochemical staining in a retrospective series of 118 sarcomas from trabectedin-treated patients to validate in vivo our in vitro observations. In cell lines, greater trabectedin sensitivity was associated with higher CUL4A expression and lower BRCA1/ERCC5, BRCA1/CUL4A, and XRCC3/CUL4A expression ratios. In agreement, BRCA1-deficient CUL4A-knockdown cells presented higher cell survival after trabectedin exposure than did scramble control cells. Lack of effect in BRCA1-proficient cells suggests that HRR impairment is key in CUL4A-mediated trabectedin sensitivity. High CUL4A expression in nontranslocation-related patients with sarcoma predicted improved progression-free survival [PFS; HR, 0.37; 95% confidence interval (CI), 0.20-0.68, P = 0.001] and overall survival (OS; HR, 0.44; 95% CI, 0.21-0.93, P = 0.026). Our observations support the notion of greater trabectedin activity in tumors exhibiting BRCAness and reveal CUL4A as a potential biomarker for definition of trabectedin target patients.
Group of Human Genetics, Human Cancer Genetics Program, Spanish National Cancer Centre (CNIO), Melchor Fernández Almagro 3, Madrid 28029, Spain. mjgarcia@cnio.es
María J
MJ
García
Laura Paula
LP
Saucedo-Cuevas
Iván
I
Muñoz-Repeto
Victoria
V
Fernández
María J
MJ
Robles
Samuel
S
Domingo
José
J
Palacios
Miguel
M
Aracil
Antonio
A
Nieto
Juan Carlos
JC
Tercero
Javier
J
Benítez
D018906:Antineoplastic Agents, Alkylating / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000401:mortality; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D044842:Cullin Proteins / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D004149:Dioxoles / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D015870:Gene Expression; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D020128:Inhibitory Concentration 50; D044005:Tetrahydroisoquinolines / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D000077606:Trabectedin; D016896:Treatment Outcome
D018906:Antineoplastic Agents, Alkylating; C114234:CUL4A protein, human; D044842:Cullin Proteins; D004149:Dioxoles; D044005:Tetrahydroisoquinolines; D000077606:Trabectedin