Insufficient radiofrequency ablation promotes human hepatoma SMMC7721 cell proliferation by stimulating vascular endothelial growth factor overexpression

Abstract

The aims of the current study were to investigate the influence of insufficient radiofrequency ablation (RFA) on the cell proliferation of the human hepatocellular carcinoma (HCC) cells, SMMC7721, and to elucidate the underlying mechanism. SMMC7721 cells were subjected to a 47°C treatment regimen to simulate insufficient RFA, in the presence or absence of KN93 [a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMKII)], PD98059 [a specific inhibitor of extracellular signal-regulated kinase (ERK)], or axitinib (a specific inhibitor of vascular endothelial growth factor (VEGF) receptor]. Cell proliferation was determined using a thiazolyl terazolium assay (MTT). The levels of CaMKII, phospho-CaMKII, ERK, phospho-ERK and VEGF were observed by western blot analysis. The results demonstrated that the 47°C treatment regimen: i) Triggered upregulation of VEGF expression in the SMMC7721 cells, which was reduced by CaMKII or ERK inhibition; ii) induced ERK activation was prevented by KN93; and iii) promoted SMMC7721 cell proliferation, which was greatly inhibited by axitinib, KN93 and PD98059. In conclusion, the results indicated that insufficient RFA promotes SMMC7721 cell proliferation by activating CaMKII/ERK-dependent VEGF overexpression.

Epidermal growth factor receptor transactivation is involved in the induction of human hepatoma SMMC7721 cell proliferation by insufficient radiofrequency ablation

“…However, one of the major challenges associated with RFA is the rapid growth of residual HCC, thus leading to high recurrence rates associated with the cancer (6,8). As reported, post-RFA local recurrence rates can reach up to 60% (14).…”

“…Our previous study demonstrated that CaMKII/ERK-dependent VEGF overexpression was involved in the 47˚C treatment-induced malignant proliferation of SMMC7721 cells (6). Thus, the present study further investigated the association between EGFR transactivation and the CaMKII/ERK/VEGF signaling cascade.…”

“…Incomplete RFA was simulated in vitro according to the authors' previously reported procedure (6). Briefly, SMMC7721 cells were seeded into 6-well plates at a density of 5x10 4 cells/well.…”

“…Currently, this nonclassical EGFR stimulation process is generally termed 'EGFR transactivation' (12 (10,13). Our previous study demonstrated that insufficient RFA promotes hepatoma cell malignancy via the Ca 2+ /calmodulin-dependent protein kinase II (CaMKII)/ERK-induced overexpression of vascular endothelial growth factor (VEGF) (6). Thus, the current study aimed to investigate whether EGFR signal transactivation is involved in HCC malignancy induced by incomplete RFA, and determine its association with the CaMKII/ERK-VEGF signaling cascade.…”

“…As the most widely used non-surgical treatment approach for HCC, RFA has numerous advantages, including its definitive therapeutic effect, minimal damage to functioning liver, simplicity, repeatability and shorter associated hospital stays (4,6). However, increasing laboratory and clinical studies have reported that residual tumor tissue following RFA exhibits more malignant growth and accelerated local recurrence compared with non-RFA treated tumors (5)(6)(7)(8). Therefore, further investigations into the molecular mechanisms underlying the undesirable effects of RFA on HCC are warranted.…”