# RPA exhaustion activates SLFN11 to eliminate cells with heightened replication stress

## TL;DR

The study shows how RPA exhaustion activates SLFN11, causing cell death in cancer cells under replication stress, especially when PrimPol is absent.

## Contribution

The paper reveals RPA exhaustion as a general mechanism for SLFN11 activation in replication stress, linking it to cisplatin sensitivity and PrimPol deficiency.

## Key findings

- SLFN11 activation occurs via RPA exhaustion and single-stranded DNA exposure in PrimPol-deficient cells.
- The USP1–WDR48 complex promotes SLFN11 activation and depends on the Fanconi anaemia pathway.
- Inhibiting DNA polymerase α rapidly activates SLFN11-dependent cell death.

## Abstract

SLFN11 is epigenetically silenced and confers chemoresistance in half of all cancers. In response to replication stress, SLFN11 triggers translation shutdown and p53-independent apoptosis, but how DNA damage activates SLFN11 remains unclear. Here through CRISPR-based screens we implicate SLFN11 as the critical determinant of cisplatin sensitivity in cells lacking primase–polymerase (PrimPol)-mediated repriming. SLFN11 and the downstream integrated stress response uniquely promote cisplatin-driven apoptosis in PrimPol-deficient cells. We demonstrate that replication protein A (RPA) exhaustion and single-stranded DNA exposure trigger SLFN11 activation and cell death when PrimPol is inactivated. We further identify the USP1–WDR48 deubiquitinase complex as a positive modulator of SLFN11 activation in PrimPol-deficient cells, revealing an addiction to the Fanconi anaemia pathway to resolve cisplatin lesions. Finally, we demonstrate that rapid RPA exhaustion on chemical inhibition of DNA polymerase α activates SLFN11-dependent cell death. Together, our results implicate RPA exhaustion as a general mechanism to activate SLFN11 in response to heightened replication stress.

Stanage et al. identify a role for transfer RNA nuclease SLFN11 in replication-stress-induced cell death in cisplatin-treated cells lacking PrimPol. SLFN11 is activated upon single-stranded DNA accumulation at stalled forks followed by replication protein A exhaustion and cell death.