Loss of CDKN2A Promoter Methylation Coincides With the Epigenetic Transdifferentiation of Uterine Myosarcomatous Cells.
Leiomyosarcoma is the most common type of uterine sarcoma and usually displays typical morphology. Heterologous leiomyosarcoma is the rarest variant, in which the tumor contains liposarcomatous, osteosarcomatous, or rhabdomyosarcomatous components. We have investigated the largest series of uterine leiomyosarcoma with a rhabdomyosarcomatous component and we have disclosed a molecular finding, which coincides to the process of transdifferentiation from smooth muscle into striated muscle phenotype. The surgical specimens of 5 rare cases of uterine leiomyosarcoma with a rhabdomyosarcomatous component were formalin fixed and paraffin embedded. In addition to hematoxylin/eosin stains, phosphotungstic acid hematoxylin staining, immunohistochemistry, and methylation-specific polymerase chain reaction the CDKN2A promoter region were performed. Leiomyosarcomatous cells were found to be strongly immunoreactive for both desmin and α-smooth muscle actin. Rhabdomyosarcomatous cells were immunoreactive for sarcomeric actin, desmin, vimentin, CD10, and p16. The methylation-specific polymerase chain reaction revealed the presence of a methylated allele and an unmethylated allele in the microdissected samples, coming from leiomyosarcomatous cells. On the contrary, 2 unmethylated alleles, molecular expression of a loss of heterozygosity, were detected in all the microdissected samples in the rhabdomyosarcomatous cells. The loss of heterozygosity methylation in the promoter region of the CDKN2A gene, occurred only in the rhabdomyosarcomatous cells with increases in both p16 and p14 expression. This event may result in an inhibition of cdk4/cdk6 activity, stabilizes the tumor suppressor protein p53, and coincides with the transdifferentiation from smooth muscle into striated muscle.
Department of Diagnostic and Clinical Medicine and of Public Health (L.R., G.B., G.S., A.M.), Section of Pathology, Policlinico Hospital, University of Modena and Reggio Emilia, ModenaDepartment of Diagnostic Imaging (E.S.), Section of Radiology, Local Health Authority, BolognaProvincial Health Care Services (T.P.), Institute of Pathology, Santa Maria del Carmine Hospital, Rovereto, Italy.
Luca
L
Roncati
Giuseppe
G
Barbolini
Giuliana
G
Sartori
Elena
E
Siopis
Teresa
T
Pusiol
Antonio
A
Maiorana
D054338:Cell Transdifferentiation; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics / Q000378:metabolism; D050763:Cyclin-Dependent Kinase Inhibitor p18 / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D007890:Leiomyosarcoma / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D019656:Loss of Heterozygosity; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012208:Rhabdomyosarcoma / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D012509:Sarcoma / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014594:Uterine Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
C401561:CDK2AP2 protein, human; C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D050763:Cyclin-Dependent Kinase Inhibitor p18; D015513:Oncogene Proteins