Journal: bioRxiv
Article Title: CDK4/6 inhibitors enhance oxaliplatin efficacy in colorectal cancer with RB-dependent and tumor-selective activity in intestinal model
doi: 10.64898/2026.04.15.718743
Figure Lengend Snippet: HCT116 cells were treated with increasing concentrations of chemotherapeutic agents in the absence or presence of fixed concentrations of CDK4/6 inhibitors, and cell viability was assessed by Calcein AM fluorescence and expressed as a percentage relative to the untreated control (100%). (A) 5-fluorouracil, (B) SN-38, (C) oxaliplatin, all of them alone or in combination with abemaciclib (300 nM). (D) Combination index (CI) analysis plotted as fraction affected versus CI for each drug combination with abemaciclib. The dashed line indicates CI = 1, where values <1 indicate synergism and values >1 indicate antagonism. (E) 5-fluorouracil, (F) SN-38, or (G) oxaliplatin, all of them alone or in combination with palbociclib (400 nM). (H) Combination index analysis plotted as fraction affected versus CI for each drug combination with palbociclib. Data are presented as mean ± SEM of at least three independent biological replicates. Bars are color-coded as follows: control (gray), chemotherapy alone (blue), abemaciclib alone (yellow), palbociclib alone (red), chemotherapy + abemaciclib (green), and chemotherapy + palbociclib (purple). Statistical significance was evaluated using ordinary one-way ANOVA followed by Šídák’s multiple comparisons test. Significance levels are indicated as follows: *p < 0.05, **p < 0.01, ***p < 0.001, ***p < 0.0001. To improve visual clarity, statistical comparisons between chemotherapy treatments alone (blue bars) and the untreated control (gray bar) are not shown in the graphs but are summarized here. ABE arm: A: CTL vs ABE ***p=0.0001; 5-FU 2.8 vs 2.8+ABE ***p=0.0005; 4.5 vs 4.5+ABE *p=0.0128; 6 vs 6+ABE ns. B: CTL vs ABE ****p<0.0001; SN-38 0.8 vs 0.8+ABE ***p=0.0009; 1.2 vs 1.2+ABE ***p=0.0004; 1.6 vs 1.6+ABE ns. C: CTL vs ABE ****p<0.0001; OXA 0.4 vs 0.4+ABE ****p<0.0001; 0.6 vs 0.6+ABE ****p<0.0001; 0.8 vs 0.8+ABE ns. PALB arm: E: CTL vs PALB ns; 5-FU 2.8 vs 2.8+PALB ns; PALB vs 2.8+PALB **p=0.0040; PALB vs 4.5+PALB ****p<0.0001; PALB vs 6+PALB ****p<0.0001; 6 vs 6+PALB *p=0.0463. F: CTL vs PALB **p=0.0071; SN-38 1.2 vs 1.2+PALB ***p=0.0008; 0.8 vs 0.8+PALB ns; 1.6 vs 1.6+PALB ns; PALB vs 1.2+PALB ***p=0.0002; PALB vs 1.6+PALB ***p=0.0003. G: CTL vs PALB *p=0.0478; OXA 0.4 vs 0.4+PALB ***p=0.0007; 0.6 vs 0.6+PALB ****p<0.0001; 0.8 vs 0.8+PALB **p=0.0041; PALB vs all OXA+PALB ****p<0.0001.
Article Snippet: The selective CDK4/6 inhibitors abemaciclib (MedChemExpress, HY-16297A) and palbociclib (MedChemExpress, HY-A0065) were used either as single agents or in combination with one of the following chemotherapeutic agents: 5-fluorouracil (5-FU; Merck, F6627), SN-38 (7-ethyl-10-hydroxycamptothecin; Cayman Chemical, 15632), and oxaliplatin (Bergamo, 1151955).
Techniques: Fluorescence, Control
![HCT116 cells (5 × 10³ cells/well) were exposed for 48 h to increasing concentrations of (A) 5-fluorouracil (0.77–7700 μM), (B) SN-38 (0.02–200 nM), (C) oxaliplatin (0.125–250 μM), and (D) <t>the</t> <t>CDK4/6</t> inhibitors abemaciclib (25–3000 nM) or palbociclib (25–6400 nM). Cell viability was assessed by Calcein AM fluorescence and expressed as a percentage of the untreated control (100%). The data are presented as the mean ± SEM of six independent biological replicates. Dose–response curves were fitted by nonlinear regression using a four-parameter logistic model (variable slope; log[inhibitor] vs. normalized response) in GraphPad Prism 8.4.3.](https://bio-rxiv-images-cdn.bioz.com/dois_ending_with_43/10__64898_slash_2026__04__15__718743/10__64898_slash_2026__04__15__718743___F1.large.jpg)
