Fig. 1

CDK4/6i treatment led to PARP1 upregulation in breast cancer patients and cells. A. PARP1 is upregulated in HR + breast cancer patients, who ultimately experience disease progression. B–C. PARP1 is highly expressed in most cancers, especially in breast cancer, according to the GEPIA database. D. The construction process of drug-resistant strains is shown in the picture. E–F. MCF7AR cell lines were confirmed to be resistant to abemaciclib with an IC₅₀ of approximately 50 μM, and PARP1 was significantly upregulated in MCF7AR cells compared with parent MCF7 cells. G. The results of transcriptome sequencing showed that PARP1 was upregulated significantly, with a 40-fold change in MCF7AR compared with the MCF7 group. H. The IC₅₀ for the CDK4/6i palbociclib in 30 breast cancer cell lines was obtained from the GDSC database and paired with corresponding PARP1 mRNA level data obtained from the CCLE database. The 30 breast cancer cell lines were divided into two groups based on the level of PARP1 mRNA, and those with a high level of PARP1 demonstrated a tendency to have a higher palbociclib IC₅₀. I. Western blot results showed that Abemaciclib treatment led to PARP1 elevation in 3 breast cancer cell lines. The results presented have been repeated in 3 biological replicates. Data, means ± SEMs, *, P < 0.05, **, P < 0.01, ***, P < 0.001