Po-303 modified p53 functionality in cancer-associated fibroblasts promotes cancer growth

Introduction p53 is a seminal tumour suppressor protein, acting as a major barrier against cancer. So far, p53 research has focused primarily on its cell-autonomous functions. Yet, p53 can also exert non-cell-autonomous effects on tumour development. Within the tumour microenvironment (stroma), cancer cells coexist with non-cancerous adjacent cells. In particular, Cancer-Associated Fibroblasts (CAFs) contribute in multiple ways to tumour progression. To assess the possible roles of p53 in CAFs, we investigated the contribution of p53 to the gene expression landscape and the biological properties of CAFs, relative to normal fibroblasts (NFs). Cancerous mutations in the TP53 gene, resulting in production of mutant p53 proteins, can lead not only to loss of its tumour suppressive functions, but often also to gain of tumor-promoting activities, associated with altered p53-dependent transcriptional programs. Of note, alterations in the regulatory networks that impinge on p53 may cause genetically wild type (wt) p53 to acquire features resembling bona fide mutant p53. However, the extent and functional impact of p53 conversion from its canonical tumour suppressive state into such ‘pseudomutant’ states in actual human tumours remains to be determined. Material and methods For co-culture experiments, mCherry-expressing H460 cells and GFP-expressing fibroblasts were seeded together. These co-cultures were subjected to Fluorescent Activated Cell Sorting (BD biosciences ). Live cell imaging was performed with a DeltaVision microscope . CAFs, and NFs from the non-cancerous margins, were isolated and it was approved by the local ethics committee and informed consent was obtained from the patients. Results and discussions Whole transcriptome analysis identified substantial differences in the transcriptional impact of p53 between CAFs and NFs. Functional assays revealed that CAF p53, while remaining genetically wt, contributes to the activated fibroblast phenotype of CAFs and promotes non-cell-autonomously tumour cell migration and invasion. Furthermore, the cancer-promoting role of CAF p53 was confirmed by co-injection of fibroblasts and tumour cells into SCID mice. Remarkably, co-cultivation with cancer cells rendered the transcriptional impact of NF p53 more similar to that of CAF p53. Conclusion The transcriptional program driven by p53 is drastically altered in CAFs. CAF p53 promotes cancer cell migration and invasion in vitro and tumour growth in vivo . Cancer cells drive rewiring of fibroblast wtp53 to a cancer-promoting state.