Journal: iScience
Article Title: Mathematical modeling of ribosome competition informs testable treatment strategies for drug-tolerant cancer persister cells
doi: 10.1016/j.isci.2026.115493
Figure Lengend Snippet: Myc-mediated downregulation of ribosome biogenesis in DTP cells (A) Immunofluorescence of nucleolar proteins, nucleophosmin 1(NPM1, green) and pescadillo (PES1, red), showing different phenotype of ribosome biogenesis center in parental and DTP cells. Representative images were shown from n = 3 biological independent experiments. Scale bars, 10 μm. (B) Quantification of nucleolus number and area per nuclear at single cell level in A375 melanoma cells. Four different regions of interest were randomly selected for image analysis, and a total of 100 cells were analyzed. Unpaired t test Mann-Whitney test was performed for statistical analyses. (C) Image-based machine learning classification by using Cellprofiler to categorize the nucleolar phenotype into positive (more number and higher granularity) and negative (less number and lower granularity) feature. (D and E) The nucleoli of DTP cells exhibited a higher proportion of negative features in two distinct DTP models. (D) A375 melanoma persister cells treated with 1 μM vemurafenib and 500 nM cobimetinib, n = 4 different regions of interest were randomly selected for image analysis, and a total of 100 cells were analyzed. (E) Lung adenocarcinoma PC9 persister cells treated with 1 μM erlotinib. N = 6 different regions of interest were randomly selected for image analysis, and a total of 100 cells were analyzed. Data are shown as mean ± SD. The Mann-Whitney nonparametric t test p values were calculated. (F and G) Lower intensity of cell proliferation marker Ki67 staining showing correlation with negative feature of nucleolar phenotype in A375 melanoma DTP cells. Representative images were shown from n = 3 biologically independent experiments. Ki67 fluorescence intensity was quantified within individual cells ( n = 30) by Cellprofiler software. The Mann-Whitney nonparametric t test p values were calculated. (H) Chromatin immunoprecipitation (ChIP) with c-Myc antibody in A375 melanoma parental (Par) and DTP cells (Per). Genomic DNA was purified and quantitative PCR was conducted to assess the enrichment levels of the corresponding c-Myc binding sequence. The data are presented as the mean ± SD from n = 3 biologically independent experiments. CCND1 enrichment level was used as a positive control. The Mann-Whitney nonparametric t test p values were calculated. (I) Levels of RPL7L and RPL39 proteins were downregulated in DTP cells compared to parental cells, as indicated by TMT mass spectrometry analysis. Data are shown as mean ± SD. The Mann-Whitney nonparametric t test p values were calculated. (J) Knockdown of c-Myc reduced global translational activity in A375 melanoma cells as indicated by polysome profiling. Inset, c-Myc shRNA analysis by western blot. n = 3 biologically independent experiments were performed showing similar results. (K) Knockdown of c-Myc enhanced the responsiveness to vemurafenib and cobimetinib treatment in SK-MEL-28 and WM983B melanoma cells. Representative results were shown from n = 3 biologically independent experiments. Data are shown as mean ± SD. (L) Clonogenic assay of A375 melanoma cells under vemurafenib and cobimetinib treatment with or without c-Myc shRNA-mediated knockdown for 3 weeks. N = 4 biologically independent experiments were performed. Data are shown as mean ± SD. The Mann-Whitney nonparametric t test p values were calculated. Corresponding clonogenic assay example images were shown for each treatment group. Combo, vemurafenib (1 μM) + cobimetinib (500 nM).
Article Snippet: The human cell lines A375, SK-MEL-28, and QBC939, as well as the mouse cell line YUMM1.7, were purchased from the American Type Culture Collection (ATCC).
Techniques: Immunofluorescence, Single Cell, MANN-WHITNEY, Marker, Staining, Fluorescence, Software, Chromatin Immunoprecipitation, Purification, Real-time Polymerase Chain Reaction, Binding Assay, Sequencing, Positive Control, Mass Spectrometry, Knockdown, Activity Assay, shRNA, Western Blot, Clonogenic Assay