Fig. 3: PRMT5 confers chemo-resistance of NPC and associates with poor prognosis of NPC.

A Right, PRMT5 expression as shown by qRT-PCR and western blot analysis in siRNA treated 5-8 F R cells. Left, the effects of PRMT5 downregulation on cell sensitivity to PTX as shown by colony formation assay. B Cell cytotoxicity assay of PTX. Cells were treated with different concentrations of PTX for 96 h. Cell viability was assessed using CellTiter-Glo reagent. Data are shown as means ± SD (n = 3). *P < 0.05; **P < 0.01. C Tumorsphere formation assay of shPRMT5 Tet-on 5-8 F R cells treated with Dox, with or without PTX. Representative images (left) and quantifications (right). Bars represent the means ± SD (n = 3). Scale bars, 200 μm. *P < 0.05; **P < 0.01; ***P < 0.001. D Tumorsphere formation assay of 5–8 F P cells with PRMT5 overexpression with or without PTX treatment. Representative images (Left) and quantifications (Right). Bars represent the means ± SD (n = 3). Scar bars, 400 μm. *P < 0.05; **P < 0.01; ***P < 0.001. E IHC analysis of PRMT5 expression in 194 nasopharyngeal carcinoma samples from patients treated with chemotherapy. PRMT5 was detected in both the nucleus and cytosol. IHC scores were calculated by multiplying the scores for the proportion of positively stained tumor cells (1, <10%; 2, 0%–50%; 3, 50%–80%; 4, >80%) and staining intensity (0, no staining; 1, weak; 2, moderate; 3, strong) by each investigator, then averaged. IHC score > 8 was used to classify tumors with high PRMT5 expression and the rest were defined as low expression. Representative images are shown. Scale bar 10 μm. F The Kaplan–Meier survival analysis for progression-free survival and locoregional recurrence-free survival of 194 patients with nasopharyngeal carcinoma with different PRMT5 expression levels, as determined in D.