Alternate splicing of the p53 inhibitor HDMX offers a superior prognostic biomarker than p53 mutation in human cancer
Menée sur diverses lignées cellulaires de cancer et des échantillons tumoraux prélevés sur des patients atteints d'un sarcome des tissus mous, cette étude suggère qu'un indicateur d'épissage alternatif de HDMX, un inhibiteur de p53, serait un meilleur biomarqueur d'atténuation de la signalisation de p53 que l'identification d'une mutation de p53
Conventional high-grade osteosarcoma is the most common primary bone malignancy. Although altered expression of the p53 inhibitor HDMX (Mdmx/Mdm4) is associated with cancer risk, progression, and outcome in other tumor types, little is known about its role in osteosarcoma. High expression of the Hdmx splice variant HDMX-S relative to the full length transcript (the HDMX-S/HDMX-FL ratio) correlates with reduced HDMX protein expression, faster progression and poorer survival in several cancers. Here, we demonstrate that the HDMX-S/HDMX-FL ratio positively correlates with less HDMX protein expression, faster metastatic progression and a trend to worse overall survival in osteosarcomas. We found that the HDMX-S/HDMX-FL ratio associated with common somatic genetic lesions connected with p53 inhibition, such as p53 mutation and HDM2 overexpression in osteosarcoma cell lines. Interestingly, this finding was not limited to osteosarcomas as we observed similar associations in breast cancer and a variety of other cancer cell lines, as well as in tumors from soft tissue sarcoma patients. The HDMX-S/HDMX-FL ratio better defined sarcoma patients with worse survival rates than p53 mutational status. We propose a novel role for alternative splicing of HDMX, whereby it serves as a mechanism by which HDMX protein levels are reduced in cancer cells that have already inhibited p53 activity. Alternative splicing of HDMX could therefore serve as a more effective biomarker for p53 pathway attenuation in cancers than p53 gene mutation.
Cancer Research , résumé, 2012