Figure 6.

Schematic illustration of the mechanism of LMP1/Pim1 signaling–promoted proliferation in NPC cells.

Notes: Based on results from the literature²⁹ and this study, the mechanism of LMP1-induced Pim1 expression regulating the proliferation of NPC cells is illustrated. EBV encodes transmembrane protein LMP1 in NPC cells, through its C-terminal activation regions 1, 2 and 3 (CTAR1, CTAR2 and CTAR3), LMP1 activates NF-κB, Jak/STAT3, PKC and AP1 signaling. Inhibition of NF-κB, PKC and Jak/STAT3 signaling by its specific blocker attenuates LMP1-enhanced Pim1 expression, while inhibition of AP1 shows no effect on Pim1 expression. Consequently, this upregulated Pim1 promotes NPC cell proliferation, while inhibition Pim1 activity by quercetagetin suppresses cell proliferation.

Abbreviations: AP-1, activator protein 1; CTAR, C-terminal activation regions; EBV, Epstein–Barr virus; NF-κB, nuclear factor κB; NPC, nasopharyngeal carcinoma; PDTC, pyrrolidine dithiocarbamate; PKC, protein kinase C; STAT3, signal transducer and activator of transcription 3.