UBA3 reduction sensitizes cancer cells to NAE inhibitors.

The NEDD8-activating enzyme (NAE), comprising NAE1 and UBA3, is an anticancer target. The relative contribution of each of these subunits toward NAE inhibitor (NAEi) efficacy remains unclear. We demonstrated a profound interdependence of NAE1 and UBA3 expression. UBA3 reduction augmented NAEi sensitivity, whereas its overexpression led to decreased sensitivity. UBA3 deficiency enhanced RKO xenograft sensitivity to SOMCL-19-133 (NAEi), which was reversed by UBA3 restoration. Cells with naturally low UBA3 expression were highly NAEi-sensitive. The criticality of UBA3 in NAEi sensitivity is not completely unexpected given that the ability of NAEi to directly bind to UBA3 is known. TCGA data showed that rectum adenocarcinoma patients with low UBA3 mRNA had poorer prognoses, and 27.16% of tumors expressed low UBA3 mRNA. We propose that low UBA3 expression may serve as a NAEi sensitivity biomarker, particularly given that MLN4924 (NAEi) phase 3 failures may be due to a lack of patient stratification. Therefore, our key findings, on the criticality of UBA3 in NAEi sensitivity, underpin future clinical evaluations.