Conventional drug sensitivity assays used to screen prospective anti-cancer agents for cytotoxicity monitor biological processes associated with active growth and proliferation, used as proxies of cell viability. However, these assays are unable to distinguish between growth-arrested (but otherwise viable) cells and non-viable/dead cells. As a result, compounds selected based on the results of these assays may only be cytostatic, halting or slowing tumour progression temporarily, without tumour eradication. Because agents capable of killing tumour cells (cytotoxic drugs) are likely the most promising in the clinic, there is a need for drug sensitivity assays that reliably identify cytotoxic compounds that induce cell death. We recently developed a drug sensitivity assay, called the RNA disruption assay (RDA), which measures a phenomenon associated with tumour cell death. In this study, we sought to compare our assay’s performance to that of current commonly used drug sensitivity assays (i.e, the clonogenic, the cell counting kit-8 and the Trypan blue exclusion assays). We found that RNA disruption occurred almost exclusively when total cell numbers decreased (cytotoxic concentrations), with little to no signal detected until cells had lost viability. In contrast, conventional assays detected a decrease in their respective drug sensitivity parameters despite cells retaining their viability, as assessed using a recovery assay. We also found that the RDA can differentiate between drug-sensitive and -resistant cells, and that it can identify agents capable of circumventing drug resistance. Taken together, our study suggests that the RDA is a superior drug discovery tool, providing a unique assessment of cell death.

用于筛选前瞻性抗癌药的细胞毒性的常规药物敏感性测定法可监测与活性生长和增殖相关的生物学过程，用作细胞生存能力的代理。但是，这些测定法无法区分生长停滞（但仍能存活）的细胞和非存活/死细胞。结果，基于这些测定的结果选择的化合物可能只是暂时抑制细胞生长，阻止或减缓肿瘤进展，而没有根除肿瘤。由于能够杀死肿瘤细胞的药物（细胞毒性药物）可能是临床上最有前途的药物，因此需要进行药物敏感性检测，以可靠地识别诱导细胞死亡的细胞毒性化合物。我们最近开发了一种药物敏感性测定方法，称为RNA破坏测定法（RDA），测量与肿瘤细胞死亡有关的现象。在这项研究中，我们试图将我们的检测方法与当前常用的药物敏感性检测方法（即克隆形成，细胞计数试剂盒8和台盼蓝排除法）。我们发现，RNA破坏几乎仅在总细胞数减少（细胞毒性浓度）时发生，直到细胞丧失活力之前几乎没有检测到信号。相反，如使用回收测定所评估，尽管细胞保留了它们的生存力，常规测定仍检测到其各自的药物敏感性参数降低。我们还发现，RDA可以区分药物敏感性细胞和耐药细胞，并且可以识别能够规避药物耐药性的药物。综上所述，我们的研究表明RDA是一种出色的药物发现工具，可提供细胞死亡的独特评估。