The WWOX tumor suppressor is essential for postnatal survival and normal bone metabolism.
The WW domain-containing oxidoreductase (WWOX) gene encodes a tumor suppressor. We have previously shown that targeted ablation of the Wwox gene in mouse increases the incidence of spontaneous and chemically induced tumors. To investigate WWOX function in vivo, we examined Wwox-deficient (Wwox(-/-)) mice for phenotypical abnormalities. Wwox(-/-) mice are significantly reduced in size, die at the age of 2-3 weeks, and suffer a metabolic disorder that affects the skeleton. Wwox(-/-) mice exhibit a delay in bone formation from a cell autonomous defect in differentiation beginning at the mineralization stage shown in calvarial osteoblasts ex vivo and supported by significantly decreased bone formation parameters in Wwox(-/-) mice by microcomputed tomography analyses. Wwox(-/-) mice develop metabolic bone disease, as a consequence of reduced serum calcium, hypoproteinuria, and hypoglycemia leading to increased osteoclast activity and bone resorption. Interestingly, we find WWOX physically associates with RUNX2, the principal transcriptional regulator of osteoblast differentiation, and on osteocalcin chromatin. We show WWOX functionally suppresses RUNX2 transactivation ability in osteoblasts. In breast cancer MDA-MB-242 cells that lack endogenous WWOX protein, restoration of WWOX expression inhibited Runx2 and RUNX2 target genes related to metastasis. Affymetrix mRNA profiling revealed common gene targets in multiple tissues. In Wwox(-/-) mice, genes related to nucleosome assembly and cell growth genes were down-regulated, and negative regulators of skeletal metabolism exhibited increased expression. Our results demonstrate an essential requirement for the WWOX tumor suppressor in postnatal survival, growth, and metabolism and suggest a central role for WWOX in regulation of bone tissue formation.
Aqeilan
Rami I
RI
Department of Molecular Virology, Immunology, and Medical Genetics, Human Cancer Genetics Program and Comprehensive Cancer Center, Ohio State University, Columbus, OH 43210, USA. rami.aqeilan@osumc.edu
Hassan
Mohammad Q
MQ
de Bruin
Alain
A
Hagan
John P
JP
Volinia
Stefano
S
Palumbo
Titziana
T
Hussain
Sadiq
S
Lee
Suk-Hee
SH
Gaur
Tripti
T
Stein
Gary S
GS
Lian
Jane B
JB
Croce
Carlo M
CM
D000818:Animals; D000831:Animals, Newborn; D001842:Bone and Bones / Q000378:metabolism*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D002843:Chromatin / Q000737:chemistry; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000378:metabolism; D010010:Osteoclasts / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D025521:Tumor Suppressor Proteins / Q000378:metabolism / Q000502:physiology*; D000074584:WW Domain-Containing Oxidoreductase
D002843:Chromatin; D025521:Tumor Suppressor Proteins; D010088:Oxidoreductases; D000074584:WW Domain-Containing Oxidoreductase; C486071:WWOX protein, human