Loss of mutant TP53 does not impair the sustained proliferation, survival or metastasis of diverse cancer cells

The tumour suppressor TP53 is the most frequently mutated gene in human cancer and these aberrations confer poor chemotherapeutic responses. Point mutations typically cluster in the DNA binding domain, with certain hot-spot residues disproportionally represented. These mutations abrogate binding of the TP53 transcription factor to DNA and thereby prevent upregulation of genes critical for tumour suppression (loss-of-function). Mutant TP53 is reported to additionally contribute to tumour development, sustained growth and metastasis not only through dominant-negative effects on wild-type TP535 but also through neomorphic gain-of-function (GOF) activities. Understanding the contributions of these postulated attributes of mutant TP53 to the development and expansion of tumours will facilitate the design of rational therapeutic strategies. Here we used CRISPR/CAS9 to delete mutant TP53 in a panel of diverse human cancer cell lines. The loss of mutant TP53 expression had no impact on the survival, proliferative capacity or metabolic state of the tumour cells, nor did it sensitise them to cellular stresses and chemotherapeutic agents. These data suggest that putative GOF effects of mutant TP53 are not universally required for the sustained survival and proliferation of fully malignant cells. Therefore, therapeutic approaches that abrogate expression or function of mutant TP53 would not be expected to have substantial impact.