ABSTRACT
The majority of tumors possess the features of hypoxia. It is generally accepted that hypoxia is a negative prognostic factor for cancer. Low levels of oxygen are able to modify basic cell metabolism status. Elucidating the basic response, including cell proliferation and migration, to hypoxia by cancer cells is important for understanding the role of hypoxia in the development of cancer. In the present study, CoCl2 stimulation was used to simulate hypoxia. A microRNA (miRNA/miR) array was used to systematically detect the changes in miRNA expression profiles. Following treatment with CoCl2 for 12 h, 15 miRNAs were markedly upregulated and 10 miRNAs were markedly decreased compared with the control. After 24 h CoCl2 incubation, 15 miRNAs were increased and 3 miRNAs were decreased compared with the control. Among them, 7 miRNAs were upregulated and 2 miRNAs were downregulated at 12 and 24 h following CoCl2 stimulation. The potential roles of these miRNA were reviewed and it was identified that the majority of them are associated with cell proliferation and migration. Additional experiments demonstrated that CoCl2 incubation inhibited the proliferation of MCF-7 cells but promoted cell migration. miR-491 may be a key miRNA for hypoxia-inhibited cell proliferation, as it was identified that hypoxia induced the downregulation of B-cell lymphoma-extra large in a miR-491-dependent manner. As the target of miR-302a, CXCR4 may be a key protein for hypoxia-promoted cell migration. In the present study, it was identified that in the early stage of hypoxia, cell proliferation was inhibited but cell migration was promoted. These results support the hypothesis that hypoxia may be a driving force for tumor cell escape from the primary tumor site to other organs, or other sites of the same organ.
ABSTRACT
Livin is a novel member of the inhibitor of apoptosis protein family that has been reported to be overexpressed in various types of human malignancy. Although several studies have demonstrated that livin may be used as an effective target for tumor therapy, few studies have investigated its role in human lung adenocarcinoma. In the present study, two different methods were used in order to investigate the tumorsuppressing effect of livin in human lung adenocarcinoma cells. Firstly, small interfering (si)RNA technology was used to down regulate livin expression; siRNA-mediated knockdown of livin was confirmed using reverse transcription quantitative polymerase chain reaction and western blot analysis, and cell proliferations was assessed using an MTT assay in vitro. Secondly, inhibition of livin expression was induced through the synergistic inhibitory effect between flavopiridol and tumor necrosis factorrelated apoptosis-inducing ligand (TRAIL). Experimental results revealed that, following transfection of the livin gene-silencing vector, the gene expression of livin was markedly decreased, SPC-A1 cell proliferation was significantly reduced and the therapeutic effect of the chemotherapy drug cisplatin was markedly improved. This growth inhibitory effect was also observed in the flavopiridol and TRAIL combination treatment group. In the flavopiridol and TRAIL combination treatment group, the protein expression of livin was significantly reduced and the survival rate of SPCA1 cells was significantly lower than the flavopiridol and TRAIL single operation group. In conclusion, the RNA silencing and the synergistic inhibitory effect between flavopiridol with TRAIL was able to effectively inhibit the expression of livin, significantly decrease SPC-A1 tumor cell proliferation and significantly enhance sensitivity to the chemotherapy drug cisplatin. These findings suggest that livin may be used as a novel target for tumor gene therapy.
Subject(s)
Adaptor Proteins, Signal Transducing/biosynthesis , Adenocarcinoma/drug therapy , Adenocarcinoma/genetics , Inhibitor of Apoptosis Proteins/biosynthesis , Lung Neoplasms/drug therapy , Lung Neoplasms/genetics , Neoplasm Proteins/biosynthesis , Adaptor Proteins, Signal Transducing/antagonists & inhibitors , Adaptor Proteins, Signal Transducing/genetics , Adenocarcinoma/pathology , Adenocarcinoma of Lung , Apoptosis/genetics , Cell Line, Tumor , Cell Proliferation/genetics , Cisplatin/administration & dosage , Gene Expression Regulation, Neoplastic , Gene Silencing , Humans , Inhibitor of Apoptosis Proteins/antagonists & inhibitors , Inhibitor of Apoptosis Proteins/genetics , Lung Neoplasms/pathology , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/geneticsABSTRACT
Vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) in primary malignant gastric lymphoma were studied, and their correlation as well as its clinical significance was analyzed. Thirty-five patients diagnosed with primary malignant gastric lymphoma were enrolled in this study. VEGF expression in the tumor tissues was detected by immunohistochemistry. Microvessel density in tumors was counted with Weidner's method and compared with MVD in normal tissues 5 cm away from tumor site. Collected data were analyzed statistically. Our results showed that VEGF expression and MVD in tumor tissues were higher than those in normal tissues, and the difference between these two groups was significant (P < 0.01). As VEGF expression was elevated, MVD was also increased in tumor tissues. Statistical analysis revealed that VEGF expression was positively correlated with MVD (r = 0.392, P < 0.05). VEGF was highly expressed in primary malignant gastric lymphoma and positively correlated with MVD. These results strongly suggest that anti-angiogenesis therapy investigated in gastric lymphoma is a prospective clinical trial.
