A genome-wide CRISPR screen to identify factors regulating sensitivity of cells to aclarubicin and identified p53 as a critical factor for cellular sensitivity suggests p53 could be an important factor to stratify patients for treatment with Aclarubicin.
Abstract
The anthracycline family, with its prime member doxorubicin, is one of the cornerstones in cancer chemotherapy and acts by poisoning topoisomerase II, resulting in DNA double-stranded breaks. One of its members, aclarubicin, is considered a distinct member of this family due to its inability to inflict DNA double-strand breaks. Despite this, aclarubicin is an effective anti-cancer drug by evicting histones, resulting in chromatin damage. How aclarubicin-induced chromatin damage induces cell death remains largely unknown. Here, we performed a genome-wide CRISPR screen to identify factors regulating sensitivity of cells to aclarubicin and identified p53 as a critical factor for cellular sensitivity. Even though aclarubicin does not induce DNA breaks, treatment resulted in swift activation of ATM independent of the MRN complex, which stabilized and activated p53, resulting in apoptosis and cell cycle arrest. Furthermore, response to aclarubicin treatment could reasonably be predicted by the p53-status of cell lines. These data suggest that ATM and p53 can be activated for apoptosis induction by at least two different pathways, DNA- and chromatin damage. Together, these data suggest p53 could be an important factor to stratify patients for treatment with Aclarubicin.
Anthracyclines are highly effective chemotherapeutic agents that cause DNA and chromatin damage. One member of the anthracyclines, aclarubicin, has recently gained therapeutic interest due to its ability to kill cancer cells through chromatin-based mechanisms, thus avoiding the off-target effects associated with DNA damage. Despite this, the molecular mechanism of action leading to aclarubicin-induced chromatin damage remains elusive. Here we performed Cleavage Under Targets and Tagmentation (CUT&Tag) of RNA polymerase II (Pol II) and other transcriptional regulators in human cells during aclarubicin treatment. We found that aclarubicin strongly disrupts the replication-coupled histone genes, resulting in a nonproductive accumulation of Pol II-transcription machinery here beyond the levels at other genes. We attribute this sensitivity to the dense Pol II loading and rapid transcription of the histone genes, which intensify the chromatin-disrupting effects of aclarubicin at these loci. Together, our findings support the effectiveness of aclarubicin as an anticancer drug and point to the histone gene cluster as a promising target for therapeutic intervention.
Kevin K. Nguyen, Matthew Wooten, K. Ahmad et al.· bioRxiv· 0 citations
Topoisomerase 2 (Top2) poisons are widely used in cancer therapy but are associated with toxicity and secondary malignancies. Top2 adduct removal requires endonuclease activity prior to repair of the resulting DNA double-strand break (DSB). We show that the non-homologous end joining (NHEJ) enzyme Artemis is a key player in the process and a major target for treatment of human B-cell acute lymphoblastic leukemia (ALL). An Artemis knockout is sensitive to etoposide treatment at nanomolar levels and has significantly more unrepaired DNA DSBs. Inhibition of the Artemis activator, DNA-dependent Protein Kinase Catalytic Subunit (DNA-PKcs), acts synergistically with Top2 poisons to further sensitize ALL cells. Genetic loss of Artemis ablates this synergy underscoring its critical role in this drug interaction. Furthermore, Artemis loss results in a significant accumulation of covalent Top2A DNA adducts following etoposide treatment and a significant increase in unrepaired DNA DSBs. As clinical data demonstrate that high Artemis expression correlates with poor survival in several cancers, our work may unlock new avenues for the treatment of aggressive cancers.
Melissa L. Folkerts, C. Hom, Angie Nguyen et al.· Communications Biology· 0 citations
Results indicate that targeted reactivation of BFL-1 and SQOR increases cell-death susceptibility in liver cancer cells, providing proof-of-concept for locus-specific epigenetic therapy in liver cancer.
Wonjin Woo, Seol-Hwa Jeong, Ayoung Hwang et al.· Molecules and Cells· 0 citations
Cisplatin (DDP), a core chemotherapeutic agent for osteosarcoma (OS), induces DNA cross‐linking to cause damage, yet the underlying regulatory mechanisms remain elusive. Our study has revealed that in DDP‐resistant osteosarcoma (OS) cells, both the expression level of the lysine acetyltransferase KAT8 and its mediated site‐specific acetylation of histone H4K16ac are significantly decreased. Using CUT&Tag technology and proteomic analysis, we demonstrated that the KAT8–H4K16ac axis modulates dynamic histone acetylation to epigenetically regulate DNA repair pathways. The biological inactivation of KAT8 results in a targeted decrease in the epigenetic mark H4K16ac at the promoter regions of genes associated with DNA repair, leading to diminished chromatin accessibility and inhibition of the p53 signaling pathway. Consequently, the DNA damage response is compromised, promoting cisplatin resistance in OS. In contrast, targeted restoration of H4K16ac reverses chemotherapy resistance through the reinstatement of chromatin dynamics and transcriptional activation of DNA repair programs. This hypothesis emphasizes the need to clarify the molecular mechanisms and signaling pathways associated with KAT8–H4K16ac, especially in relation to apoptotic pathways, which could offer new insights and justifications for treatment strategies in cisplatin‐resistant osteosarcoma.
Zhen-Qun Zhao, Guohui Yu, Shikui Wu et al.· Med Research· 0 citations
The failure of current DNA damage response strategies to adequately distinguish tumor from normal tissue remains a major barrier to durable cancer control. BCN077 is a first-in-class small-molecule activator of human single strand DNA-binding protein 2 (hSSB2), a conserved single-stranded DNA binding complex that coordinates replication stress responses, DNA repair, and checkpoint recovery. We hypothesized that pharmacologic activation of hSSB2 would create a therapeutically exploitable divergence: lethal replication stress in genomically unstable tumors, but epithelial protection in normal tissues exposed to radiation or chemotherapy.
BCN077 was evaluated across cancer cell lines, the NCI-60 panel, and in vivo tumor and radiation injury models. Mechanistic studies assessed DNA damage, replication stress, spindle checkpoint signaling, and mitotic catastrophe using γH2AX, phospho-H3, BUB1, MAD2L1, comet analysis, clonogenic survival, and morphologic criteria. Tumor efficacy was tested in aggressive and treatment-resistant models, including BRAF V600E colorectal cancer, and normal tissue protection was assessed in irradiation settings relevant to gastrointestinal injury.
BCN077 demonstrated broad anti-tumor activity across diverse cancer types and selectively triggered mitotic catastrophe in checkpoint-defective tumor cells characterized by unresolved DNA damage, aberrant mitotic entry, and loss of proliferative capacity. In contrast, normal cells with intact checkpoint function were comparatively spared. In vivo, BCN077 enhanced tumor control and showed marked protective activity in irradiated or chemo exposed normal epithelium, preserving intestinal architecture and improving survival after radiation exposure. These findings support a mechanism in which hSSB2 activation intensifies genotoxic stress beyond the tolerable threshold in cancer cells while reinforcing recovery and survival programs in normal tissues.
hSSB2 is an emerging druggable vulnerability with a compelling dual therapeutic profile. BCN077 may define a new class of agents that simultaneously improve tumor control and reduce treatment-limiting toxicity, representing a genuine translational opportunity to expand the therapeutic window of radiation and chemotherapy. This strategy is especially relevant for malignancies in which checkpoint failure and replication stress are common, including triple-negative breast cancer not amenable to PARP inhibition and head and neck cancers where improved tumor ablation must be balanced against epithelial sparing.
Andrew J. Norris, Elizabeth M. Singer, Rishi Man Chugh, Payel Bhanja, Julian P. Whitelegge, William H. McBride, Jesus M. Rodriguez, Natalie Isaghulian, Alexander M. Varady, Subhrajit Saha. Activation of hSSB2/1 by BCN077 Induces Tumor-Selective Mitotic Catastrophe While Protecting Irradiated Epithelium: A New Therapeutic Paradigm for Expanding the Cancer Treatment Window [abstract]. In: Proceedings of AACR Drug Discovery and Development (AACR D3) Conference; 2026 Jul 21-24; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(14_Suppl):Abstract nr A080.
Andrew Norris, Elizabeth M. Singer, R. Chugh et al.· Clinical Cancer Research· 0 citations
Homologous recombination (HR) is a high-fidelity DNA repair pathway responsible for the resolution of double-strand breaks, with the RAD51 recombinase playing a pivotal role through the formation of nucleoprotein filaments on single-stranded DNA. Overexpression of RAD51 is frequently observed in cancer cells, where it promotes genome stability under genotoxic stress and contributes to acquired resistance to DNA-damaging chemotherapeutic agents. In this study, we report the identification of a novel stilbene-derived compound, the disodium salt of 4,4'-diphenylcarbamate stilbene-2,2'-disulfonic acid (DPDS), as a novel compound that modulates RAD51 monomer-monomer interactions and reduces its binding to single-stranded DNA and ATP, processes that are critical for filament assembly and homologous recombination. Furthermore, DPDS enhances the cytotoxic effect of cisplatin in DU145 prostate cancer cells and was associated with reduced RAD51 nuclear foci formation and increased accumulation of DNA double-strand breaks. Notably, DPDS did not significantly affect cell viability in the four cellular models evaluated under our experimental conditions and displayed lower intrinsic cytotoxicity than DIDS (4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) and emzadirib. Collectively, these findings support DPDS as a chemical modulator of RAD51 activity may enhance cisplatin sensitivity in DU145 prostate cancer cells.
Lucie Fonteneau, H. Benhelli-Mokrani, Céline Robiou Du Pont et al.· Biochemical Pharmacology· 0 citations
