Abstract P92: C11ORF68 is a repressor of inflammatory response under normal and replication stress conditions

Abstract Introduction: Unresolved replication stress (RS) or DNA damage, and inflammation often lead to genomic instability – a feature of many diseases including cancer. Therefore, understanding the molecular foundation of these phenomena is crucial for identifying potential biomarkers or therapeutic targets. Our lab has identified an uncharacterized protein that is symmetrically dimethylated by PRMT5 under hydroxyurea (HU)-induced RS. Therefore, we hypothesize that C11ORF68 is involved in inflammatory and RS response. Materials and methods: MCF10A normal breast epithelial cells was used. Depletion of C11ORF68 using siRNA and dicer siRNA (dsiRNA) systems were used to evaluate its function. RNA-seq, qPCR, western blotting and immunofluorescence were used to evaluate the basal and HU-induced inflammatory response. Results: RNA-seq of C11ORF68-depleted cells displayed a basal and RS-induced upregulation of several inflammatory response pathways including interferon alpha and gamma response, and TNF signaling via NF-kB. Selected genes such as CXCL10 and IFIT1 were validated to be upregulated at both basal and RS conditions. This increase in inflammatory gene transcription may be due accumulation of dsDNA in the cytoplasm of C11ORF68-depleted cells. The mechanism of dsDNA leakage into the cytoplasm is currently being investigated. Surprisingly, the observation of cytoplasmic dsDNA was not accompanied with increased DNA damage as there was no basal increase in DNA damage or RS markers such as γH2AX and 53BP1. However, C11ORF68-depleted cells exhibited attenuated activation of DNA damage/RS pathways such as lowered PIKK activation and less repair foci formation after addition of DNA damaging/RS agents. Conclusions: Our data suggests that C11ORF68 potentially acts as a repressor of both basal and RS-induced inflammatory response. C11ORF68 may also be a mediator of early DDR. Mechanisms behind how a nucleolar protein plays role in regulating these phenomena are underway, which may help us understand the involvement of a nucleolar protein in controlling inflammatory and DNA damage/RS responses. Citation Format: Toh Chin Min Clarissa, Hoang Mai Phuong, Hong Liang, Anand Jeyasekharan. C11ORF68 is a repressor of inflammatory response under normal and replication stress conditions [abstract]. In: Proceedings of Frontiers in Cancer Science 2025; 2025 Nov 5-7; Singapore. Philadelphia (PA): AACR; Cancer Res 2026;86(13_Suppl):Abstract nr P92.