دانلود رایگان مقاله انگلیسی پارامتر جدید مهار رشد برای آزمایشات تکثیر سلولی - وایلی 2017

ABSTRACT

Cell proliferation assays are performed by four decades to test the anti-proliferative activity of natural products and synthetic compounds in cell cultures. In cancer research, they are widely employed to evaluate drug efficacy in in vitro tumor models, such as established cell lines, primary cultures and recently developed three-dimensional tumor organoids. In this manuscript, we demonstrated that current employed parameters used by researchers to quantify in vitro growth inhibition, IC50 and GI50, lead to a misinterpretation of results based on the exponential, and not linear, proliferation of the cells in culture. Therefore, we introduce a new parameter for the analysis of growth inhibition in cell proliferation assays, termed relative population doubling capacity, that can be employed to properly quantify the antiproliferative activity of tested compounds and to compare drug efficacy between distinct cell models. This article is protected by copyright.

DISCUSSION AND CONCLUSIONS

Cell proliferation assays are routinely performed to evaluate in vitro efficacy of tested compounds in anticancer drug discovery research. Relative cell number (R) and percentage of growth (PG) are parameters widely employed by researchers to show the efficacy of tested compounds on the proliferation of cells in culture because of their simplicity and intuitiveness (Boyd and Paull, 1995; Yoshida et al., 1975). However, here we show here that both parameters are function of cell proliferation in tested cell model (Figure 1 and Figure 3). In order to experimentally evaluate our hypothesis, we treated two representative cell lines with a well-known chemotherapy agent, etoposide, and employed live-cell imaging technique to monitor the number of cells at several times of treatment (Figure 2). We also show here that PGS dependency to cell proliferation is due to the exponential, and not linear, growth of cell in culture (Figure 4). As consequence, a drug that shows a high R or PGS value after 48 hours of treatment could show lower values after longer period of treatment because of the increased growth of untreated cells and not the putative additive effects of the drug. As another example, a cell line with a fast proliferation rate in culture would show lower R or PGS values than a “slower” cell line and would be inferred more sensitive to a drug when comparing drug efficacy between the two cell lines. This is of particular relevance in studies that compare drug efficacy in distinct cell models, as cell lines, with distinct growth properties. For instance, non-tumor cells, which usually tend to duplicate slower than the tumor counterpart, shows higher IC50 and GI50 values than tumor cells and could be misinterpreted as less sensitivity to tested compounds. Same misinterpretation could occur in studies of personalized medicine that associate drug sensitivity to genetic mutations or expression profiles, since higher sensitivity will be attributed to faster growing cell lines independently by their genome or transcriptome profiles.