Cuendet Muriel, Christov Konstantin, Lantvit Daniel D, Deng Yunfan, Hedayat Samad, Helson Lawrence, McChesney James D, Pezzuto John M
Program for Collaborative Research in the Pharmaceutical Sciences, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, IL, USA.
Clin Cancer Res. 2004 Feb 1;10(3):1170-9. doi: 10.1158/1078-0432.ccr-0362-3.
Bruceantin has been shown to induce cell differentiation in a number of leukemia and lymphoma cell lines. It also down-regulated c-MYC, suggesting a correlation of down-regulation with induction of cell differentiation or cell death. In the present study, we focused on multiple myeloma, using the RPMI 8226 cell line as a model.
The effects of bruceantin on c-MYC levels and apoptosis were examined by immunoblotting, 4',6-diamidino-2-phenylindole staining, evaluation of caspase-like activity, and 3,3'-dihexyloxacarbocyanine iodide staining. The potential of bruceantin to inhibit primary tumor growth was assessed with RPMI 8226 xenografts in SCID mice, and apoptosis in the tumors was evaluated by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay.
c-MYC was strongly down-regulated in cultured RPMI 8226 cells by treatment with bruceantin for 24 h. With U266 and H929 cells, bruceantin did not regulate c-MYC in this manner. Apoptosis was induced in the three cell lines. In RPMI 8226 cells, apoptosis occurred through proteolytic processing of procaspases and degradation of poly(ADP-ribose) polymerase. The mitochondrial pathway was also involved. Because RPMI 8226 cells were the most sensitive, they were used in a xenograft model. Bruceantin treatment (2.5-5 mg/kg) resulted in a significant regression of tumors without overt toxicity. Apoptosis was significantly elevated in tumors derived from animals treated with bruceantin (37%) as compared with the control tumors (14%).
Bruceantin interferes with the growth of RPMI 8226 cells in cell culture and xenograft models. These results suggest that bruceantin should be reinvestigated for clinical efficacy against multiple myeloma and other hematological malignancies.
布鲁斯他汀已被证明可诱导多种白血病和淋巴瘤细胞系发生细胞分化。它还下调了c-MYC，提示下调与细胞分化或细胞死亡诱导之间存在相关性。在本研究中，我们以RPMI 8226细胞系为模型，聚焦于多发性骨髓瘤。
通过免疫印迹、4',6-二脒基-2-苯基吲哚染色、半胱天冬酶样活性评估和3,3'-二己基氧杂羰花青碘化物染色，检测布鲁斯他汀对c-MYC水平和细胞凋亡的影响。用RPMI 8226异种移植瘤评估布鲁斯他汀抑制原发性肿瘤生长的潜力，并通过末端脱氧核苷酸转移酶介导的缺口末端标记法评估肿瘤中的细胞凋亡。
用布鲁斯他汀处理培养的RPMI 8226细胞24小时后，c-MYC被强烈下调。对于U266和H929细胞，布鲁斯他汀未以这种方式调节c-MYC。三种细胞系均诱导了细胞凋亡。在RPMI 8226细胞中，细胞凋亡通过前半胱天冬酶的蛋白水解加工和聚（ADP-核糖）聚合酶的降解发生。线粒体途径也参与其中。由于RPMI 8226细胞最敏感，因此将其用于异种移植模型。布鲁斯他汀治疗（2.5 - 5 mg/kg）导致肿瘤显著消退且无明显毒性。与对照肿瘤（14%）相比，用布鲁斯他汀治疗的动物来源的肿瘤中细胞凋亡显著升高（37%）。
布鲁斯他汀在细胞培养和异种移植模型中干扰RPMI 8226细胞的生长。这些结果表明，应重新研究布鲁斯他汀对多发性骨髓瘤和其他血液系统恶性肿瘤的临床疗效。
