Tumor cell-intrinsic PD-1 regulates chemotherapy resistance in colorectal cancer cells by activating downstream MAPK signaling
摘要
Colorectal cancer (CRC) remains a significant clinical challenge. Immunotherapy against programmed cell death 1 protein (PD-1) in CRC has limited success. Intriguingly, CRC cells express PD-1 (ciPD-1) intrinsically, and we report here its function with respect to chemotherapy.
MethodsWe evaluated the associations between ciPD-1 expression and disease progression, overall survival, and upregulation of survival pathways in human CRC tumors. Expression levels of ciPD-1 in CRC cells were modulated to evaluate its biological role in vitro.
ResultsHigh expression levels of PD-1 in CRC tumors are associated with inferior outcomes; these tumors are also more aggressive and drug-resistant. Expression levels of ciPD-1 in CRC cells increase during 5-FU or CPT-11 treatment and are accompanied by upregulation of cell survival pathways. When ciPD-1 is inhibited, the cell-killing effects of 5-FU or CPT-11 were significantly increased. Our data show that ciPD-1 signaling occurs via MAPK signaling in CRC cells to support survival under stress conditions.
ConclusionsCRC tumors with high levels of ciPD-1 are more aggressive and associated with inferior outcomes. Reducing ciPD-1 levels in CRC cells make them more sensitive to chemotherapy. The aggregate results suggest that using a PD-1 inhibitor with first-line treatments in CRC could improve therapeutic efficacy.