Assessing p53 in clinical contexts: unlearned lessons and new perspectives

There is compelling evidence for the central role of the p53 pathway in human neoplasia but, despite an enormous literature, the clinical utility of assessing this pathway remains ambiguous. Even simple questions about the assessment of p53 status in clinical samples remain unanswered and the literature is confusing and often contradictory. The p53 pathway is certainly complicated and the biochemical mechanisms for regulating the function of p53 and its downstream consequences are rabbinical in complexity. This perspective considers this complexity and the reasons why establishing the true utility of clinical assessment of p53 has proven to be so difficult. Indeed, recent observations regarding the existence of alternate splice variants of p53, the complexity of p53 regulation, and the existence of allelic variants of p53 and its regulators with distinct functionality makes the situation even more complex. Problems with the available assays are considered and the need to consider an array of methodological issues is emphasized. Newer strategies including analysis of the expression of downstream targets of p53 and the use of threshold strategies to measure p53 protein may provide more robust measures of the p53 pathway in clinical settings, perhaps coupled with cheap sequencing-based approaches for mutation (and polymorphism) detection. However, progress will only be made if these methodological issues are resolved and robust assays are performed in the context of appropriately powered studies in clinical trial settings.