[The effects of β-elemene on rabbit VX2 laryngeal carcinoma and factors associated with tumor growth and metastasis]

OBJECTIVE

To investigate the inhibition effect of β-elemene on the growth and metastasis of laryngeal carcinoma and the underlying mechanism.

METHODS

Sixty-six rabbits were vaccinated with suspension of VX2 cancer tissues to establish a rabbit laryngeal carcinoma model and then they were randomly treated with the injection of 0.9% sodium chloride solution (as a control), cisplatin, or β-elemene from the seventh day after vaccination. The rabbits were sacrificed three weeks after vaccination. The laryngeal tumor was dissected. and the volume of tumor and the inhibitory rate of tumor growth were measured. The expressions of PCNA (proliferation cell nuclear antigen), Bcl-2 (B-cell lymphoma-2) and VEGF-D (vascular endothelial growth factor D) in tumor were semiquantitatively examined by immunohistochemistry.

RESULTS

The inhibition rates of tumor growth in β-elemene-treated group and the cisplatin-treated group were 48.5% and 51.4%, respectively. The expressions of Bcl-2 in β-elemene-treated group and cisplatin-treated group were significantly lower than the control (P<0.05), but with no significant difference between β-elemene-treated group and cisplatin-treated group. The expression of PCNA in β-elemene-treated group was significantly decreased compared to control group (P<0.05). The expression of VEGF-D in β-elemene-treated group was lower than that in control group or the cisplatin-treated group (P<0.05).

CONCLUSION

β-elemene can inhibit the growth of rabbit VX2 laryngeal tumor, which may be associated with the inhibition of factors related to tumor growth and metastasis.

Decreased efficiency of gamma-ray-induced DNA double-strand break rejoining in malignant transformants of human bronchial epithelial cells generated by alpha-particle exposure

PURPOSE

To investigate the cytogenetic changes and DNA double-strand break (DSB) rejoining of transformed cell lines generated from human bronchial epithelial cells by alpha-particle exposure.

MATERIALS AND METHODS

Transformed cell lines were derived from the HPV 18-immortalized human bronchial epithelial cell line BEP2D generated by 1.5 Gy of alpha-particles emitted by a 238Pu source. Two cell lines, BERP35T1 and BERP35T4, were investigated. Karyotypes were analyzed by trypsin/Giemsa banding. Cell survival was estimated by colony assay. PFGE was used to detect the DNA DSB. mRNA expression was analyzed by RT-PCR.

RESULTS

Abnormal chromosomes 2 and 12 with elongated long arm and deletions of chromosomes 2, 12, 13 and 17 were observed in the transformed cell lines. BERP35T4 showed a much higher proportion of polyploid cells (40.5%) compared with parental BEP2D cells and the BERP35TI cell line (5%). BERP35T1 and BERP35T4 showed a markedly lower capacity for rejoining of gamma-ray-induced DNA DSB and increased radiosensitivity compared with parental BEP2D cells. The analysis of mRNA levels revealed a 2.5- to 6.5-fold down-regulated expression of the DNA repair genes XRCC-2, XRCC-3 and Ku80 in BERP35T1 and BERP35T4 cells.

CONCLUSION

The karyotypic changes of chromosomes 2, 12, 13 and 17 and the deficiency of DSB rejoining could be related to the malignant transformation processing of BEP2D cells initiated by alpha-particle exposure.