Objective: To explore the effect of HMGB1 on the VEGF-C expression and proliferation of esophageal squamous cancer cells as well as its possible mechanism.
Methods: A cassette encoding siRNA targeting HMGB1 mediated by rAAV was constructed, the rAAV-siHMGB1-hrGFP, and a vector encoding siRNA mismatching HMGB1 was constructed, the rAAV-miHMGB1-hrGFP. This experiment in vitro included three groups, namely, the blank control group (group A) of KYSE150 cells transfected by rAAV-hrGFP, negative mismatch control group (group B) of KYSE150 cells transfected with rAAV-miHMGB1-hrGFP, and RNA interference group (group C) of KYSE150 cells transfected with rAAV-siHMGB1-hrGFP. We examined the expression of HMGB1 mRNA and protein in the three group cells by real-time PCR and Western blot after 24 h and 48 h, respectively. Then, VEGF-C expression and cell proliferation in the three group cells with or without sRAGE, as an inhibitor of RAGE signal pathway, were assayed by ELISA and MTT after 24 h.
Results: The expression of HMGB1 mRNA and protein in KYSE150 cells in vitro in the group C transfected with rAAV-siHMGB1-hrGFP at the final concentration of 2×10(6) v.g/cell was significantly lower than that of the group A or B after 24 h and 48 h (P < 0.01). The VEGF-C expression of KYSE150 cells was (502.43 ± 13.10) pg/ml in the group C, significantly reduced in comparison with that of the group A (686.40 ± 10.94) pg/ml or group B (682.31 ± 9.61) pg/ml after 24 h (P < 0.05). At the same time, the proliferation of KYSE150 cells in the group C was significantly inhibited compared with that of groups A and B after 24 h (P < 0.01). Moreover, sRAGE at the final concentration of 0.2 µg/ml inhibited the VEGF-C expression and proliferation of KYSE150 cells compared with the corresponding group without sRAGE after 24 h (P < 0.01 or P < 0.05). However, there was no significant difference of the VEGF-C expression and proliferation of KYSE150 cells with sRAGE in the group C compared with that of cells with sRAGE of the group A or group B after 24 h (P > 0.05).
Conclusions: In esophageal squamous cell carcinoma, HMGB1 can promote the VEGF-C expression and proliferation of the cancer cells through RAGE signal pathway, and HMGB1-RAGE may become a potential target for cell proliferation and lymph node metastasis of this cancer.