Abstract
Colorectal cancer (CRC) is one of the most prevalent and deadly forms of cancer. It is universally treated with a combination of the DNA damaging chemotherapy drugs irinotecan, 5-Fluorouracil (5-FU), and oxaliplatin. CHD1L is a novel oncogene that plays critical roles in chromatin remodeling and DNA damage repair, as well as the regulation of malignant gene expression. We show that an inhibitor of CHD1L, OTI-611, when combined with chemotherapy significantly increases DNA damage in CRC cell lines. OTI-611 also synergizes with SN-38, 5-FU, and oxaliplatin in killing CRC tumor organoids. We also demonstrate that, as in breast cancer, OTI-611 traps CHD1L, PARP1, and PARP2 onto chromatin. The entrapment of CHD1L causes the deprotection of PAR chains in the nucleus, ultimately resulting in cell death by CHD1Li-mediated PARthanatos, as measured by AIF translocation to the nucleus. Finally, the combination of low doses of OTI-611 with irinotecan significantly reduces tumor volume and extends survival in CRC xenograft mouse models compared to irinotecan alone. The combination of standard of care chemotherapy drugs with CHD1Li represents a promising advancement in future therapeutic strategies for CRC and other cancers driven by CHD1L.