ABSTRACT
Renal cell carcinoma (RCC) is the most lethal of all urological cancers and tumor angiogenesis is closely related with its growth, invasion, and metastasis. Recent studies have suggested that epidermal growth factor-like domain multiple 7 (EGFL7) is overexpressed by many tumors, such as colorectal cancer and hepatocellular carcinoma; it is also correlated with progression, metastasis, and a poor prognosis. However, the role of EGFL7 in RCC is not clear. In this study, we examined how EGFL7 contributes to the growth of RCC using a co-culture system in vitro and a xenograft model in vivo. Downregulated EGFL7 expression in RCC cells affected the migration and tubule formation of HMEC-1 cells, but not their growth and apoptosis in vitro. The level of focal adhesion kinase (FAK) phosphorylation in HMEC-1 cells decreased significantly when co-cultured with 786-0/iEGFL7 cells compared with 786-0 cells. After adding rhEGFL7, the level of FAK phosphorylation in HMEC-1 cells was significantly elevated compared with phosphate-buffered saline (PBS) control. However, FAK phosphorylation was abrogated by EGFR inhibition. The average size of RCC local tumors in the 786-0/iEGFL7 group was noticeably smaller than those in the 786-0 cell group and their vascular density was also significantly decreased. These data suggest that EGFL7 has an important function in the growth of RCC by facilitating angiogenesis.
Subject(s)
Carcinoma, Renal Cell/genetics , Endothelial Growth Factors/genetics , Kidney Neoplasms/genetics , Neovascularization, Pathologic/genetics , RNA, Small Interfering/administration & dosage , Angiogenesis Inhibitors/genetics , Animals , Apoptosis/genetics , Calcium-Binding Proteins , Cell Cycle/genetics , Cell Line, Tumor , Cell Movement/genetics , Cell Proliferation/genetics , Down-Regulation , EGF Family of Proteins , Endothelial Growth Factors/biosynthesis , ErbB Receptors/antagonists & inhibitors , Female , Focal Adhesion Protein-Tyrosine Kinases/metabolism , Gefitinib , Humans , Mice , Mice, Nude , Neoplasm Invasiveness , Phosphorylation , Protein Kinase Inhibitors/pharmacology , Quinazolines/pharmacology , RNA Interference , Xenograft Model Antitumor AssaysABSTRACT
BACKGROUND: Renal-cell carcinoma (RCC) is resistant to almost all chemotherapeutics and radiation therapy. ß-Elemene, a promising anticancer drug extracted from a traditional Chinese medicine, has been shown to be effective against various tumors. In the present study, anti-tumor effects on RCC cells and the involved mechanisms were investigated. METHODS: Human RCC 786-0 cells were treated with different concentrations of ß-elemene, and cell viability and apoptosis were measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Protein expression was assayed by western blotting. Autophagy was evaluated by transmission electron microscopy. RESULTS: ß-Elemene inhibited the viability of 786-0 cells in a dose- and time-dependent manner. The anti-tumor effect was associated with induction of apoptosis. Further study showed that ß-elemene inhibited the MAPK/ERK as well as PI3K/Akt/mTOR signalling pathways. Moreover, robust autophagy was observed in cells treated with ß-elemene. Combined treatment of ß-elemene with autophagy inhibitors 3-methyladenine or chlorochine significantly enhanced the anti-tumor effects. CONCLUSIONS: Our data provide first evidence that ß-elemene can inhibit the proliferation of RCC 786- 0 cells by inducing apoptosis as well as protective autophagy. The anti-tumor effect was associated with the inhibition of MAPK/ERK and PI3K/Akt/mTOR signalling pathway. Inhibition of autophagy might be a useful way to enhance the anti-tumor effect of ß -elemene on 786-0 cells.