Department of Immunology, Zhuhai Campus of Zunyi Medical University, 519040 Zhuhai, China.
Department of Pharmacy, Zhuhai Campus of Zunyi Medical University, 519040 Zhuhai, China.
Toxicol In Vitro. 2023 Sep;91:105631. doi: 10.1016/j.tiv.2023.105631. Epub 2023 Jun 17.
The direct antitumor effect of bevacizumab (BEV) has long been debated. Assessment of the direct cytotoxic activities of drugs is usually conducted via in vitro experiments, of which tetrazolium-based colorimetric assays are widely employed to measure the direct antitumor activity of BEV. This study aimed to investigate whether tetrazolium-based colorimetric assays are applicable when evaluating the cytotoxicity of BEV against tumor cells. Our results showed that BEV significantly augmented tumor-cell mitochondrial metabolism. Enhanced mitochondrial metabolism caused changes in cellular oxidation-and-reduction environment and upregulated succinate dehydrogenase, which in turn promoted the reduction of tetrazolium to produce formazan. Increased formazan formation resulted in underestimation of the in vitro direct antitumor effect of BEV. Furthermore, inhibition of mitochondrial hypermetabolism partially corrected the underestimation of colorimetric assays in evaluating the direct antitumor activity of BEV. Our findings suggest that tetrazolium-based colorimetric assays are unsuitable for accurately assessing the in vitro cytotoxicity of anti-VEGF drugs and may be the methodological reason for the controversial direct antitumor effect of BEV.
贝伐珠单抗（bevacizumab，BEV）的直接抗肿瘤作用一直存在争议。药物的直接细胞毒性作用的评估通常通过体外实验进行，其中基于噻唑蓝的比色法广泛用于测量 BEV 的直接抗肿瘤活性。本研究旨在探讨基于噻唑蓝的比色法是否适用于评估 BEV 对肿瘤细胞的细胞毒性。我们的结果表明，BEV 显著增强了肿瘤细胞的线粒体代谢。增强的线粒体代谢导致细胞氧化还原环境发生变化，并上调琥珀酸脱氢酶，进而促进了噻唑蓝的还原，产生甲臜。甲臜形成增加导致体外直接抗肿瘤作用的 BEV 被低估。此外，抑制线粒体过度代谢部分纠正了比色法在评估 BEV 直接抗肿瘤活性时的低估。我们的研究结果表明，基于噻唑蓝的比色法不适用于准确评估抗 VEGF 药物的体外细胞毒性，这可能是 BEV 直接抗肿瘤作用存在争议的方法学原因。
