Fig 1: HIP1 is required for NSUN2-mediated MM cell growth. (A) mRNA expression of HIP1 in mock, shNSUN2, and shNSUN2 + oeHIP1 groups. (B) NSUN2 and HIP1 protein level in mock, shNSUN2, and shNSUN2 + oeHIP1 groups. (C) mRNA expression of NSUN2 in mock, shNSUN2, and shNSUN2 + oeHIP1 groups. (D) CCK8 assay is performed to assess the proliferation of NSUN2-knockdown RPMI8226 cells after HIP1 overexpression. (E) HIP1 rescues the increase of cell apoptosis induced by NSUN2 knockdown. Data are represented as the mean ± SEM (n = 3 independent experiments). (F) Apoptosis percentage of mock, shNSUN2, and shNSUN2 + oeHIP1 groups detected by FACS analysis. ***p < 0.001, ****p < 0.0001, ###p < 0.001, ####p < 0.0001 (* indicates mock vs. shNSUN2, # indicates shNSUN2 vs. shNSUN2 + oeHIP1). (G-I) The subcutaneous xenograft tumor formation in mice injected with Mock, shNSUN2 and shNSUN2 + oeHIP1 RPMI8226 cells. Macroscopic photographs (H). Statistical analysis of the tumor size (H) and weights (I). (J) p-AMPK and p-JNK protein level in Mock, shNSUN2, and shNSUN2 + oeHIP1 groups. NSUN2, NOP2/Sun RNA methyltransferase family member 2; HIP1, huntingtin interacting protein 1; AMPK, AMP-activated protein kinase; JNK, c-Jun Nterminal kinase; SEM, standard error of the mean.