Background:The tumor suppressor p53 is mutated in approximately 50% of human cancers.In breast tumors, mutations occur in about 30% of cases and often drive disease progression and therapy resistance.Recently, long non-coding RNAs (lncRNAs) have emerged as critical effectors within the p53 network, fine-tuning cell fate decisions.This study aimed to identify and characterize p53-regulated lncRNAs with functional relevance in breast cancer biology. Methods:We integrated differential expression analysis (using TCGA data) with public ChIP-Seq datasets to screen for lncRNAs that are both differentially expressed and directly bound by p53.Candidate validation was performed in p53-wild-type cell lines (MCF7 and ZR-75-1) and in p53-knockout clones generated via CRISPR-Cas9.We assessed transcriptional regulation using RT-qPCR after Nutlin-3A treatment and validated promoter binding via ChIP-qPCR.Functional roles were evaluated using siRNA-mediated silencing, overexpression vectors, and viability/clonogenic assays, both in basal conditions and under doxorubicin treatment.Results: Through our in-silico analysis, we identified AC003088.1 as a candidate.Its expression was significantly induced by Nutlin-3A in wild-type cells, and ChIP-qPCR confirmed direct p53 binding to its promoter region.Functionally, silencing AC003088.1 reduced cell viability and clonogenic capacity in wild-type cells, indicating it is essential for their basal growth.In contrast, silencing had no significant effect on the basal viability of p53-knockout clones, suggesting that in the absence of p53, cells adapt to survive independently of this lncRNA.However, overexpression of AC003088.1 increased viability in both wild-type and knockout lines, demonstrating its intrinsic ability to promote cell growth.Regarding drug response, while silencing reduced viability in untreated wild-type cells, this difference disappeared when cells were treated with doxorubicin or Nutlin-3A. Conclusions:AC003088.1 is a transcriptional target of p53, validated by ChIP and Nutlin-3A induction.Our results suggest it acts as a pro-survival factor, potentially maintaining basal cell viability under non-stressing conditions.
Ramadan et al. (Fri,) studied this question.