AGO2 promotes tumor progression in KRAS-driven mouse models of non–small cell lung cancer

Abstract

Lung cancer is the deadliest malignancy in the United States. Non–small cell lung cancer (NSCLC) accounts for 85% of cases and is frequently driven by activating mutations in the gene encoding the KRAS GTPase (e.g., KRASG12D). Our previous work demonstrated that Argonaute 2 (AGO2)—a component of the RNA-induced silencing complex (RISC)—physically interacts with RAS and promotes its downstream signaling. We therefore hypothesized that AGO2 could promote KRASG12D-dependent NSCLC in vivo. To test the hypothesis, we evaluated the impact of Ago2 knockout in the KPC (LSL-KrasG12D/+;p53f/f;Cre) mouse model of NSCLC. In KPC mice, intratracheal delivery of adenoviral Cre drives lung-specific expression of a stop-floxed KRASG12D allele and biallelic ablation of p53. Simultaneous biallelic ablation of floxed Ago2 inhibited KPC lung nodule growth while reducing proliferative index and improving pathological grade. We next applied the KPHetC model, in which the Clara cell–specific CCSP-driven Cre activates KRASG12D and ablates a single p53 allele. In these mice, Ago2 ablation also reduced tumor size and grade. In both models, Ago2 knockout inhibited ERK phosphorylation (pERK) in tumor cells, indicating impaired KRAS signaling. RNA sequencing (RNA-seq) of KPC nodules and nodule-derived organoids demonstrated impaired canonical KRAS signaling with Ago2 ablation. Strikingly, accumulation of pERK in KPC organoids depended on physical interaction of AGO2 and KRAS. Taken together, our data demonstrate a pathogenic role for AGO2 in KRAS-dependent NSCLC. Given the prevalence of this malignancy and current difficulties in therapeutically targeting KRAS signaling, our work may have future translational relevance.

Argonaute 2 modulates EGFR–RAS signaling to promote mutant HRAS and NRAS-driven malignancies

“…Recently, small molecule inhibitors of KRAS G12C point mutations have shown promise in human trials ( 69 , 70 ); however, no specific inhibitors of mutant NRAS or HRAS have been successfully developed to date ( 71 ). With the goal of identifying potentially druggable interactors with mutant RAS proteins, our group recently identified the novel KRAS–AGO2 interaction ( 9 ) and described its role in promoting both pancreatic ( 11 ) and NSCLC ( 12 ). Importantly, this interaction was specific to AGO2 and not the other Argonaute isoforms ( 9 ).…”

“…In addition, we recently extended these initial observations in a mutant Kras -driven mouse model of pancreatic ductal adenocarcinoma (PDAC) with co-knockout of Ago2 ( 11 ). Furthermore, Ago2 ablation in a mutant Kras- driven nonsmall cell lung cancer (NSCLC) mouse model significantly reduced tumor burden and altered downstream Kras signaling ( 12 ). These combined studies demonstrated an important role for the AGO2–RAS interaction in promoting a KRAS -driven oncogenic state.…”

DNA and RNA Binding Proteins: From Motifs to Roles in Cancer

“…The functions of AGO2 in tumorigenesis are diverse and range from high levels associated with poor prognosis in HCC [ 149 ], ovarian carcinoma [ 150 ], and gastric cancer [ 151 ], or mediating the elevation of oncogenic miR-378a-3p in Burkitt lymphoma [ 152 ], to its low expression as an indicator of poor prognosis in CRC patients [ 153 ]. AGO2 protein–protein interactions (e.g., KRAS and AGO2) are involved in the progression of pancreatic ductal adenocarcinoma [ 154 ] and NSCLC [ 155 ]. Studies of these multilevel effects are in progress and may offer patient specific targeted treatment, e.g., AGO2, as a delivery vehicle for inhibitory miRNAs [ 156 ].…”

Sex-dependent development of Kras-induced anal squamous cell carcinoma in mice

“…Activated Kras G12D refers to the successful Cre-mediated excision of the Lox-Stop sequence, allowing for transcription of the mutant Kras allele. To determine the tissue specific activation of the Kras G12D mutation, we followed the standard method first published by Hingorani [8,9] and further utilized by other groups working with this Lox-Stop-Lox conditional Kras mouse strain [10][11][12]. Genomic DNA was isolated from tail, pancreas, anus and anal tumor from KC mice.…”