[F31] Therapeutic Targeting of CCNE1 Gene Amplification in High-Grade Serous Ovarian Cancer Using Triplex Forming Oligonucleotides

Description

PROJECT SUMMARY High-grade serous ovarian cancer (HGSOC), the deadliest gynecologic cancer, is characterized by persistent TP53 mutations, chromosomal instability, and a lack of targetable oncogenic mutations. A major contributor to treatment resistance is the amplification of Cyclin E1 (CCNE1), found in about 20% of cases. CCNE1 encodes a key regulator of the G1 to S cell-cycle transition; when amplified, Cyclin E1 accelerates S-phase entry, disrupts replication origin control, and increases replication stress, forcing tumor cells to rely heavily on DNA-damage response pathways for survival. Current therapeutic efforts have focused on inhibiting CDK2, the kinase partner of Cyclin E1, but efficacy has been limited due to off-target toxicity and compensation through CDK1-mediated signaling. These limitations underscore the need for alternative therapeutic strategies that directly exploit vulnerabilities created by CCNE1 amplification. Triplex-forming oligonucleotides (TFOs) offer a novel and highly specific approach for targeting these tumors. TFOs bind to polypurine regions within DNA, forming triplex structures that stall replication forks and cause DNA double-strand breaks. Preliminary data show that CCNE1-targeted TFOs selectively induce DNA damage and apoptosis in CCNE1-amplified HGSOC cell lines, with minimal effects in non-amplified models. This suggests that CCNE1-driven replication stress creates a highly specific therapeutic vulnerability. This proposal investigates both the mechanistic basis and therapeutic potential of CCNE1-targeted TFOs. Aim 1 will define how triplex formation induces DNA damage in a sequence-specific manner within the CCNE1 locus and determine the mechanism by which replication dynamics influence cellular sensitivity. This will be accomplished using non-denatured metaphase chromosome spreads to confirm locus-specific binding, END- seq to map TFO-induced DNA breaks at nucleotide resolution, genome-wide EdU-based assays to profile replication-origin usage, replication timing, and S-phase progression, and DNA fiber analysis to quantify replication-fork speed and restart at single-molecule resolution. Aim 2 will evaluate the therapeutic activity of CCNE1-targeted TFOs, alone and in combination with DNA damage-response inhibitors, and evaluate their antitumor efficacy in CCNE1-amplified xenograft models using a validated nucleic acid delivery platform. This research is conceptually innovative in applying a TFO-based platform to a gene-amplification-driven cancer subtype where dysregulated replication and impaired checkpoint control create unique therapeutic vulnerabilities. By integrating mechanistic insights with translational testing, the proposed studies aim to establish a novel, gene-amplification-directed therapeutic strategy for CCNE1-amplified HGSOC, a population with an urgent and unmet clinical need. Istituzione: YALE UNIVERSITY PI: Anthony Minnah Progetto: 1F31CA318351-01

Sectors

Source

Source: reporter.nih.gov