ABSTRACT
Transcription factors encoded by HOX genes are vital in the determination of cell fate and identity during embryonic development. In certain malignancies, HOX genes also behave as oncogenes. The present study demonstrated suppression of the invasive tendency of glioblastoma multiforme U-118 and U-138 cells by the introduction of the antisense fragments of HOXA6 and B13 genes using electroporation. The invasion index indicated 79 and 72% reductions in the invasive ability of antisense HOXA6 and B13, respectively. No significant differences in the invasive index of the parental and mock cells of each HOX gene were observed (invasive index, 0.75-0.91; P=0.05). A reduction in invasion tendency was also observed following betulinic acid (BA) treatment: The results from the matrigel assay analysis clearly demonstrated a significant inhibition in the invasive behaviour of U-118 and U-138 cell lines from day 15 following BA treatment, with a maximum effect on day 30. The invasion index demonstrated 62 and 65% reductions in invasion ability in the U-118 and U-138 cell lines, respectively. The suppression of HOXC6 and B13 expression by the introduction of the corresponding antisense fragments in addition to BA reduced invasion tendency in U-118 and U-138 cell lines. The mechanism underlying the association between the HOX gene and invasive behavior in glioma cells is yet to be understood. However, the anti-invasive behavior of BA may aid understanding of the mechanism in future studies.
ABSTRACT
OBJECTIVE: Previous studies have shown that Fructus Ligustri Lucide (FLL) can be used to improve the tumor cells sensitivity to chemotherapeutics and promote cell death. However, the mechanism by which FLL mediate this effect is unclear. In the present study, ethyl acetate extracts of FLL induced cell apoptosis in human neuroglioma cell was investigated. METHODS: The cell viability was detected by the CCK8 assay. The cell apoptosis was assessed by annexin V-PI double-labeling staining and hoechst 33342 staining. The protein expression of cell cycle regulators and tumor suppressors were analyzed by western blotting. RESULTS: Treatment of human neuroglioma cell with FLL induced cell death in a dose-and time-dependent manner by using CCK8 assay. Consistent with the CCK8 assay, the flow cytometry results showed that the proportion of the early and terminal phase of apoptosis cells had gained after FLL treatment as compared to untreatment group. Moreover, human neuroglioma cells were exposed to the ethyl acetate extracts of FLL for 48 h, which resulted in an accumulation of cells in G2/Mphase. Apoptotic bodies were clearly observed in human neuroglioma cells that had been treated with FLL for 48 h and then stained with Hochest 33342. The expression of Cyclin B1, CDC2 and cdc25C were downregulated upon FLL treatment in human neuroglioma cells. The expression level of Cyclin B1, CDC2 and cdc25C was negatively correlated with the time of treatment by FLL. In contrast, p53, p21 and p16 were obviously upregulated by FLL treatment in a time-dependent manner. CONCLUSIONS: These results confirmed that FLL could induce apoptosis in human neuroglioma cells, the underlying molecular mechanisms, at least partially, through activation p21/p53 and suppression CDC2/cdc25C signaling in vitro.
