The human homologues of murine double minute 2 (MDM2) and 4 (MDM4) negatively regulate p53 tumour suppressor activity and are reported to be frequently overexpressed in human malignancies, prompting clinical trials with drugs that prevent interactions between MDM2/MDM4 and p53. Bone marrow samples from 111 patients with acute myeloblastic leukaemia, myelodysplastic syndrome or chronic myelomonocytic leukaemia were examined for protein (fluorescence-activated cell sorting) and messenger RNA (mRNA) expression (quantitative polymerase chain reaction) of MDM2, MDM4 and tumour protein p53 (TP53). Low protein expression of MDM2 and MDM4 was observed in immature cells from patients with excess of marrow blasts (>5%) compared with CD34+ /CD45low cells from healthy donors and patients without excess of marrow blasts (<5%). The mRNA levels were indistinguishable in all samples examined regardless of disease status or blast levels. Low MDM2 and MDM4 protein expression were correlated with poor survival. These data show a poor correlation between mRNA and protein expression levels, suggesting that quantitative flow cytometry analysis of protein expression levels should be used to predict and validate the efficacy of MDM2 and MDM4 inhibitors. These findings show that advanced disease is associated with reduced MDM2 and MDM4 protein expression and indicate that the utility of MDM2 and MDM4 inhibitors may have to be reconsidered in the treatment of advanced myeloid malignancies.
- MeSH
- akutní myeloidní leukemie * genetika MeSH
- lidé MeSH
- messenger RNA genetika metabolismus MeSH
- myelodysplastické syndromy * genetika MeSH
- myši MeSH
- nádorový supresorový protein p53 genetika MeSH
- proteiny buněčného cyklu genetika metabolismus MeSH
- protoonkogenní proteiny c-mdm2 genetika metabolismus MeSH
- protoonkogenní proteiny genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Few proteins are more studied than the p53 tumour suppressor, but what have we learned from these studies and what do we really know about p53 that can benefit clinical practice? The DNA sequence encoding p53 is frequently mutated in cancers but the functional outcomes of single mutations, in respect to loss or gain of different activities, especially in relation to immune evasion, are not clear. This illustrates p53's complexity which even after 40 years keeps providing surprises, but also explains why it has not yet lived up to its potential to benefit cancer treatment. We have reassessed a few key experiments that shaped the p53 field and we take a closer look at the interpretations of these experiments: what they have taught us, the resulting dogmas, and their potential clinical importance. One outcome is a more dynamic view of p53 in terms of its activity, its regulation, and downstream effectors, which will benefit the clinical application of p53 for diagnosis, prognosis, and therapy. Mutations and regulatory factors can have different effects on p53 activity depending on context, important but neglected aspects when interpreting p53 and its pathways in cancers. Even though p53 is undoubtedly unique as a multifunctional hub in different cellular pathways, the concept of a factor taking up different functions within a regulatory pathway during different conditions is not. In this sense, p53 continues to lead the way for a better understanding of the cellular and molecular mechanisms underlying cancer development in vivo. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
