Expression of Bcl-2 Gene in Human Renal Cell Carcinoma Associated with Drug Resistance and Metastatic Potential

Jeong, Tae Yung; Choi, Han Yong; Lee, Sang Ik

Abstract

PURPOSE: To investigate whether the up-regulation of Bcl-2 gene expression may be associated with chemotherapy resistance and malignant progression in human renal cell carcinomas (HRCC).
MATERIALS AND METHODS
The HRCC cell line, SN12C, was cultured in MEM medium, supplemented with 10% FBS. Full length of Bcl-2 cDNA was obtained using the sense primer (5'-ATGGCGCACGCTGGGAGAACGG-3') and the antisense primer (5'-TCACTTGTGGCTCAGATAGG-3') and inserted into SN12C cells to establish stable cells expressing the Bcl-2 gene (SN12C/smcb2). To investigate the response to doxorubicin in orthotropic organs, SN12C/smcb2 and parental cells were implanted into the subcapsular renal tissue of nude mice (n=5). The mice were treated with doxorubicin (8mg/kg) on days 8 and 15 following tumor cell implantation. Tumor tissues, obtained from the kidneys and lungs, were ex vivo cultured (SN12C/smcb2-kidney and SN12C/smcb2-lung, respectively). To compare the metastatic potential in these cell lines, the gelatinolytic activity was measured by zymogram and the expression of type IV collagenase (MMP-9) examined by western blot.
RESULTS
In the in vitro study, the SN12C/smcb2 was more resistant to doxorubicin than the parental cells, and treatment and those cells produced a higher rate of tumor formation and metastasis. The SN12C/ smcb2-kidney showed higher gelatinolytic activity than the parental cells. Higher expression levels of type IV collagenase were detected in the SN12C/smcb2-lung and SN12C/smcb2-kidney, but barely detected in SN12C.
CONCLUSIONS
The up-regulation of Bcl-2 gene expression in HRCC cells induces drug resistance to doxorubicin and increases the metastatic potential. Although the drug resistance induced by Bcl-2 over-expression enhances distant metastasis (lung), the up-regulation of Bcl-2 may enhance the malignant potential of tumor cells and produce distant metastasis.