ABSTRACT
Objective:To explore the effects of deleted in lung and esophageal cancer 1 (DLEC1) on osteosarcoma cells and the underlying mechanism.Methods:Immunohistochemical staining for DLEC1 was scored in sixteen paired osteosarcoma tissues and adjacent normal tissues obtained. The present study was conducted on human osteosarcoma 143B cells which were randomly divided into two groups, pDC316-DLEC1 transfection group and pDC316-Null transfection group. Differences in the proportion of EdU-positive cells, cell cycle distribution, proportion of apoptosis cells, number of migrating and invasive cells, expression of epithelial-mesenchymal transformation (EMT) markers (E-cadherin and vimentin), relative protein expression levels of NF-κB, AKT and ERK signaling pathways were assessed between the pDC316-DLEC1 and pDC316-Null transfection groups in in vitro study. The subcutaneous inoculation model and tail vein injection model were developed to evaluate the differences in subcutaneous tumor volume, subcutaneous tumor weight and pulmonary tumor nodules between the above two groups in in vivo study.Results:The DLEC1 immunostaining scores for osteosarcoma tissues and adjacent normal tissues were 2.88±1.15 and 4.25±1.06, respectively. The proportions of EdU-positive cells (36.47%±1.90% vs 51.47%±2.89%) and S phase cells (33.31%±0.61 vs 43.77%±1.47%) were decreased, while G0/G1 phase cells (46.87%±0.73% vs 35.47%±1.14%) and apoptotic cells (13.83%±1.01% vs 3.30%±0.26%) were increased in the pDC316-DLEC1 transfection group compared to those in the pDC316-Null transfection group. Decreased number of migrating cells (199.00±12.53 vs 369.67±10.02) and invasive cells (104.67±9.07 vs 299.67±12.06) and relative expression of vimentin mRNA (0.59±0.02 vs 1.00±0.02) and protein (0.54±0.08 vs 1.00±0.00) were observed in the pDC316-DLEC1 transfection group, while relative expression of E-cadherin mRNA (2.40±0.05 vs 1.00±0.02) and protein(1.98±0.10 vs 1.00±0.00) in the pDC316-DLEC1 transfection group were higher than those in the pDC316-Null transfection group. The relative protein expression of NF-κB (p65), p-AKT (Ser473) and p-ERK (Thr202/Tyr204) in the pDC316-DLEC1 transfection group were decreased by 51.67%±4.04%, 64.67%±5.51% and 48.67%±4.73% compared to those in the pDC316-Null transfection group. In in vivo study, 143B cells in the pDC316-DLEC1 transfection group formed smaller (320.00±145.22 mm 3vs 798.00±221.94 mm 3) and lighter (0.49±0.17 g vs 0.88±0.14 g) subcutaneous tumors and less metastatic lung nodules (7.71±1.80 vs 20.86±3.53) compared with those in the pDC316-Null transfection group. Conclusion:Overexpression of DLEC1 could suppress the NF-κB/AKT/ERK signaling pathways in 143B cells, which further induces G0/G1 arrest and apoptosis that ultimately inhibits cell proliferation and reduces the metastatic potential through reversing EMT.
ABSTRACT
OBJECTIVE@#To investigate the effect of the chemoprotectant tempol on the anti-tumor activity of cisplatin (DDP).@*METHODS@#The cellular toxicity of tempol in human colon cancer SW480 cells and mouse colon cancer CT26 cells were evaluated using MTT and cell counting kit-8 assays. CalcuSyn software analysis was used to determine the interaction between tempol and DDP in inhibition of the cell viability. A subcutaneous homograft mouse model of colon cancer was established. The mice were randomly divided into control group, tempol group, cisplatin group and tempol + DDP treatment group with intraperitoneal injections of the indicated agents. The tumor size, body weight and lifespan of the mice were measured, and HE staining was used to analyze the cytotoxic effect of the agents on the kidney and liver. Immunohistochemistry and Western blotting were performed to detect the expression of Bax and Bcl2 in the tumor tissue, and TUNEL staining was used to analyze the tumor cell apoptosis. The level of reactive oxygen species (ROS) in the tumor tissue was determined using flow cytometry.@*RESULTS@#Tempol showed inhibitory effects on the viability of SW480 and CT26 cells. CalcuSyn software analysis showed that tempol had a synergistic anti-tumor effect with DDP (CI < 1). In the homograft mouse model, tempol treatment alone did not produce obvious anti-tumor effect. HE staining showed that the combined use of tempol and DDP alleviated DDP-induced fibrogenesis in the kidneys, but tempol also reduced the anti-tumor activity of DDP. Compared with the mice treated with DDP alone, the mice treated with both tempol and DDP had a significantly larger tumor size ( < 0.01) and a shorter lifespan ( < 0.05). Tempol significantly reversed DDP-induced expression of Bax and Bcl2 in the tumor tissue and tumor cell apoptosis ( < 0.001), and obviously reduced the elevation of ROS level in the tumor tissue induced by DDP treatment ( < 0.05).@*CONCLUSIONS@#Tempol can attenuate the anti-tumor effect of DDP while reducing the side effects of DDP. Caution must be taken and the risks and benefits should be carefully weighed when considering the use of tempol as an anti-oxidant to reduce the toxicities of DDP.