Single-cell transcriptomics uncovers that cell-to-cell communication controls p53 activation

Conventional chemotherapy remains a cornerstone of cancer treatment and is highly effective in the adjuvant and neoadjuvant settings. However, therapeutic resistance, especially in the metastatic context, limits its long-term efficacy. While significant progress has been made in elucidating mechanisms of chemotherapy resistance, the role of cell-to-cell communication in modulating treatment response remains largely unexplored. Here, we combined microfluidic technology with single-cell RNA sequencing (scRNA-seq) to directly compare the transcriptional responses of cells in communication versus those in isolation. Upon dox treatment, we observed robust activation of the p53 pathway in communicating cells, whereas this response was markedly impaired in isolated cells. Moreover, pharmacological inhibition of caveolar-mediated endocytosis mimics the loss of p53 activation, further implicating this pathway in the communication-dependent regulation of chemotherapy response. This finding uncovers a previously unrecognized and essential role for paracrine signalling in mediating p53-dependent responses to chemotherapy. Our study highlights the critical importance of cell-to-cell communication in shaping therapeutic outcomes and opens new avenues for understanding and potentially overcoming chemotherapy resistance.