Ahn Kwang-Sung, Bae Eunkyung, Jeon Seong Soo, Yoon Sung-Soo, Lee Young-Yuil, Choi Han-Yong
Clinical Research Center, Samsung Biomedical Research Institute, Department of Urology, Sungkyunkwan University, Seoul, Republic of Korea.
Tumour Biol. 2007;28(3):181-8. doi: 10.1159/000103381. Epub 2007 Jun 1.
Dysfunction in apoptosis has been suggested to play an important role in the development of a distant metastasis. The Bcl-2 gene plays a key role in the response to chemotherapeutic agents, and its upregulation protects the cells from apoptosis by inactivating the Bax proteins through heterodimerization of Bcl-2/Bax. However, there is no direct evidence showing that the upregulation of Bcl-2 increases the antiapoptotic effects against chemotherapeutic agents and is associated with the production of a distant metastasis. In this study, the role of Bcl-2 in the production of distant metastasis was investigated by examining the activity of caspase-3 and the expression of matrix metalloproteinases (MMPs) after transfecting the Bcl-2 gene into human renal cell carcinoma cells (SN12C). In addition, the production of a distant metastasis was examined in an orthotopic animal model. In vitro, the SN12C/smb2 cells were more resistant to doxorubicin (DXR) than the untreated parental cells. The IC50 of the SN12C/smb2 was 50% higher than that of the parental cells. In addition, the caspase-3 activity of the SN12C/smb2 cells was lower than that of the parental cells after the DXR treatment. On the other hand, there was no difference in the expression of MMP-2 and MMP-9 between the SN12C and SN12C/smb2 cell lines. However, the SN12C/smb2 cells had a higher metastatic potential than the parental cells in the orthotopic animal model. Unlike the results from the in vitro analysis, the expression of MMP-2 and MMP-9 in the kidney tumors produced by the SN12C/smb2 cells was higher than in the kidney tumors produced by the SN12C/vector. These results show that the upregulation of Bcl-2 in human renal cell carcinoma cells induces drug resistance to DXR. Moreover, Bcl-2 induced the expression of MMP in tumors grown in the orthotopic sites even though no appreciable effects were observed in the in vitro condition. When the in vitro and in vivo data were combined, it appears that the Bcl-2 gene initially affects the response to DXR. The cells that survive the DXR treatment then have a chance to become metastatic by increasing the levels of MMP in an orthotopic environment.
细胞凋亡功能障碍被认为在远处转移的发生中起重要作用。Bcl-2基因在对化疗药物的反应中起关键作用，其上调通过Bcl-2/Bax异二聚体化使Bax蛋白失活来保护细胞免于凋亡。然而，没有直接证据表明Bcl-2的上调增加了对化疗药物的抗凋亡作用并与远处转移的产生相关。在本研究中，通过将Bcl-2基因转染到人肾癌细胞（SN12C）后检测caspase-3活性和基质金属蛋白酶（MMPs）的表达，研究了Bcl-2在远处转移产生中的作用。此外，在原位动物模型中检测了远处转移的发生情况。在体外，SN12C/smb2细胞比未处理的亲代细胞对阿霉素（DXR）更具抗性。SN12C/smb2的IC50比亲代细胞高50%。此外，DXR处理后，SN12C/smb2细胞的caspase-3活性低于亲代细胞。另一方面，SN12C和SN12C/smb2细胞系之间MMP-2和MMP-9的表达没有差异。然而，在原位动物模型中，SN12C/smb2细胞比亲代细胞具有更高的转移潜能。与体外分析结果不同，SN12C/smb2细胞产生的肾肿瘤中MMP-2和MMP-9的表达高于SN12C/载体产生的肾肿瘤。这些结果表明，人肾癌细胞中Bcl-2的上调诱导了对DXR的耐药性。此外，尽管在体外条件下未观察到明显影响，但Bcl-2诱导了原位生长肿瘤中MMP的表达。当将体外和体内数据结合起来时，似乎Bcl-2基因最初影响对DXR的反应。在DXR处理中存活下来的细胞随后有机会通过在原位环境中增加MMP水平而发生转移。
