Promoter methylation of DNA homologous recombination genes is predictive of the responsiveness to PARP inhibitor treatment in testicular germ cell tumors. Issue 4 (2nd March 2021)

• Record Type: Journal Article
• Authors: Lobo, João; Constâncio, Vera; Guimarães‐Teixeira, Catarina; Leite‐Silva, Pedro; Miranda‐Gonçalves, Vera; Sequeira, José Pedro; Pistoni, Laura; Guimarães, Rita; Cantante, Mariana; Braga, Isaac; Maurício, Joaquina; Looijenga, Leendert H. J.; Henrique, Rui; Jerónimo, Carmen
• Is Part Of: Molecular oncology. Volume 15:Issue 4(2021)
• Page Start: 846
• Page End: 865
• Publication Date: 2021-03-02
• Subjects: DNA methylation -- DNA repair -- homologous recombination -- Olaparib -- PARP inhibitors -- testicular germ cell tumors; Cancer -- Molecular aspects -- Periodicals; 616.994005
• DOI: 10.1002/1878-0261.12909
• Languages: English
• ISSNs: 1574-7891

Abstract

Abstract : Testicular germ cell tumors (TGCTs) are the most common cancers in men aged 15–39 years and are divided into two major groups, seminomas and nonseminomas. Novel treatment options are required for these patients, to limit side effects of chemotherapy. We hypothesized that promoter methylation of relevant homologous recombination (HR) genes might be predictive of response to poly‐ADP ribose polymerase inhibitors (PARPis) in TGCTs. We report a study pipeline combining in silico, in vitro, and clinical steps. By using several databases and in silico tools, we identified BRCA1, RAD51C, PALB2, RAD54B, and SYCP3 as the most relevant genes for further investigation and pinpointed specific CpG sites with pronounced negative correlation to gene expression. Nonseminomas displayed significantly higher methylation levels for all target genes, where increased methylation was observed in patients with more differentiated subtypes and higher disease burden. We independently performed second‐line targeted validation in tissue series from TGCT patients. A moderate and/or strong anti‐correlation between gene expression (assessed by RNA‐sequencing) and promoter methylation (assessed by 450k array) was found, for all of the targets. As a proof of concept, we demonstrated the sensitivity of TGCT cell lines to Olaparib, which associated with differential methylation levels of a subset of targets, namely BRCA1 and RAD51C . Our findings support the use of HR genes promoter methylation as a predictor of the therapeutic response to PARPis in patients with TGCT. Abstract : We report a study pipeline for exploring whether aberrant promoter methylation of genes involved in the homologous recombination pathway determines responsiveness to PARP inhibitors in testicular germ cell tumor patients. In silico analyses were followed by validation using quantitative methylation‐specific PCR. We showed differential response of germ cell tumor cell lines to Olaparib, associated with BRCA1 / RAD51C promoter methylation.