Figure 9: HOPX enhances the sensitivity of NPC cells to DDP.

(a) Dose–response curves of CNE2 and SUNE1 cells that stably overexpressed the vector or HOPX following DDP (0, 0.625, 1.25, 2.5, 5 and 10 μg ml⁻¹) treatment. Mean±s.d.; *P<0.01 compared with vector; Student’s t-tests. (b–e) CNE2 cells stably overexpressed the vector or HOPX were injected into the dorsal flank of the mice. The mice were randomly divided into four groups (n=5 per group) and treated with normal saline or DDP (4 mg kg⁻¹). These data are representative of five independent experiments (each mouse sample was considered as an independent experiment). (b) Representative picture of xenograft tumours in nude mice. (c,d) The growth curves of the tumour volumes in normal saline (c) or DDP (d) treatment group. Mean±s.d.; *P<0.01 compared with vector; Student’s t-tests. (e) The tumour weights in normal saline- or DDP-treatment group. Mean±s.d.; *P<0.01 compared with vector; Student’s t-tests. (f) Schematic summary of the HOPX-HDAC2/SRF-SNAIL signalling pathway. HOPX suppresses metastasis and enhances chemosensitivity in NPC via the recruitment of histone deacetylase HDAC2 to epigenetically inhibit SRF-dependent SNAIL transcription. This suppression effect could partially release from the HOPX hypermethylation.