Expression and prognosis analysis of PEG10 in MF. (A) Volcano plot of upregulated (red) and downregulated (blue) DEGs (fold change ≥2 or ≤−2 and P <.05) between MF-LCT and MF-NLCT group and PEG10 gene pointed out in green color. (B) PEG10 mRNA expression in lesion-biopsied samples with different T stages of MF and MF-LCT. *P < .001, n = 110. qRT-PCR, real-time quantitative reverse transcription PCR. (C) Representative immuno-histochemical evaluation of PEG10 on lesion-biopsied samples from MF-LCT and MF-NLCT patients, IgG isotype controls serve as negative controls. Original magnification ×200, insets ×400, scale bar = 50 μm. (D) Immunofluorescence (IF) costaining of PEG10 (red) and CD3 (green) on a lesional biopsy specimen of tumor-stage MF-LCT. Pautrier’s microabscess pointed out with a dashed line circle. (E,F) IF costaining of PEG10 (red) and TOX (green). (E) PEG10 (red) and Ki-67 (green). (F) On lesional biopsy specimens of tumor-stage MF-LCT. DAPI (blue) used to visualize cell nuclei. Original magnification x400, scale bar = 25 μm. (G) The structure of PEG10 coding sequence (CDS) and protein isoforms. (H,I) PEG10 mRNA (H) and protein (I) expression levels among 7 CTCL lines and CD4+ T cells from normal controls (NCD4+). (J) OS and PFS of MF patients stratified by PEG10 expression from a discovery cohort of 49 RNA-seq samples and validation cohort of extended 70 MF samples via Kaplan-Meier survival analysis. (K) TTNT for HDACis in PEG10-low and PEG10-high patients via Kaplan–Meier analysis (n = 21 treatment episodes). **P < .05; ***P < .01.