Prkar1a is an osteosarcoma tumor suppressor that defines a molecular subclass in mice
Sam D. Molyneux, … , Lawrence S. Kirschner, Rama Khokha
Sam D. Molyneux, … , Lawrence S. Kirschner, Rama Khokha
Published August 9, 2010
Citation Information: J Clin Invest. 2010;120(9):3310-3325. https://doi.org/10.1172/JCI42391.
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Research Article Oncology

Prkar1a is an osteosarcoma tumor suppressor that defines a molecular subclass in mice

Abstract

Some cancers have been stratified into subclasses based on their unique involvement of specific signaling pathways. The mapping of human cancer genomes is revealing a vast number of somatic alterations; however, the identification of clinically relevant molecular tumor subclasses and their respective driver genes presents challenges. This information is key to developing more targeted and personalized cancer therapies. Here, we generate a new mouse model of genomically unstable osteosarcoma (OSA) that phenocopies the human disease. Integrative oncogenomics pinpointed cAMP-dependent protein kinase type I, α regulatory subunit (Prkar1a) gene deletions at 11qE1 as a recurrent genetic trait for a molecularly distinct subclass of mouse OSA featuring RANKL overexpression. Using mouse genetics, we established that Prkar1a is a bone tumor suppressor gene capable of directing subclass development and driving RANKL overexpression during OSA tumorigenesis. Finally, we uncovered evidence for a PRKAR1A-low subset of human OSA with distinct clinical behavior. Thus, tumor subclasses develop in mice and can potentially provide information toward the molecular stratification of human cancers.

Authors

Sam D. Molyneux, Marco A. Di Grappa, Alexander G. Beristain, Trevor D. McKee, Daniel H. Wai, Jana Paderova, Meenakshi Kashyap, Pingzhao Hu, Tamara Maiuri, Swami R. Narala, Vuk Stambolic, Jeremy Squire, Josef Penninger, Otto Sanchez, Timothy J. Triche, Geoffrey A. Wood, Lawrence S. Kirschner, Rama Khokha

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Figure 4

A molecularly defined mouse OSA subclass exhibiting RANKL overexpression.

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A molecularly defined mouse OSA subclass exhibiting RANKL overexpression...
(A) PKA+ and PKA– mouse OSAs show equivalent histological characteristics. Shown are H&E-stained end stage tumors from MOTO mice of more than 20 weeks of age in the PKA– (top) and PKA+ (bottom) groups. Scale bars: 50 μm. (B) Unsupervised analysis using the cAMP/PKA/skeletal gene set for 13 MOTO OSA tumors highlights distinct subclass representing PKA CNAs (green indicates Prkar1a deletion; red indicates Prkaca amplification; and gray indicates no PKA CNA). (C) Three-way overlap of overexpressed or underexpressed genes in the PKA+, PKA– MOTO OSA, and the cAMP/PKA/skeletal gene set. (D) qPCR of RANKL and OPG RNA in WT bone and 13 MOTO tumors (colored rectangles are same as in B). (E) Western blots and (F) qPCR of the indicated molecules in the 7F2-OSB and moto cell lines. (G) Western blots of total and phospho-CREB protein in cells treated with (+) or without (–) 1.5 mM cAMP for 30 minutes, and qPCR shows the effect of 8-hour cAMP treatment on RANKL and OPG. (H) Effect of 30 minutes 25 μM Forskolin/40 μM IBMX with or without 30 μM H89 treatment on phospho-CREB levels and on the expression of RANKL and OPG. Endogenous actin or GAPDH serve as protein loading controls. All analyses were performed in triplicate on 3 separate occasions; the hairline divider indicates samples run on the same blot. *P < 0.05 and **P < 0.01 indicate significance relative to 7F2-OSB or to untreated control. Data are represented as mean ± SEM.