HMGI-C and HMGI(Y) immunoreactivity correlates with cytogenetic abnormalities in lipomas, pulmonary chondroid hamartomas, endometrial polyps, and uterine leiomyomas and is compatible with rearrangement of the HMGI-C and HMGI(Y) genes.
High-mobility group (HMG) proteins are nonhistone nuclear proteins that play an important role in the regulation of chromatin structure and function. HMGI-C and HMGI(Y) are members of the HMGI family of HMG proteins, and their expression in adult tissues generally correlates with malignant tumor phenotypes. However, HMGI-C and HMGI(Y) dysregulation as a result of specific rearrangements involving 12q15 and 6p21, the respective chromosomal sites in which the HMGI-C and HMGI(Y) genes are located, is also identified in a variety of common benign mesenchymal tumors, such as lipomas and uterine leiomyomata. The general prevalence of HMGI-C and HMGI(Y) protein expression and its correlation with chromosomal alterations in these benign tumors are unknown. We analyzed 95 human tumors (20 lipomas, 21 pulmonary chondroid hamartomas, 26 uterine leiomyomata, and 28 endometrial polyps) representing a selection of the benign lesions in which karyotypic alterations involving the chromosomal regions 12q15 and 6p21 are frequently detected. All cases were successfully karyotyped and some of them analyzed by fluorescent in situ hybridization with probes spanning the HMGI-C and HMGI(Y) genes. The results of this study demonstrate that expression of HMGI-C or HMGI(Y) is a common occurrence in lipomas, pulmonary chondroid hamartomas, leiomyomata, and endometrial polyps; that it correlates with 12q15 and 6p21 chromosomal alterations (p < 0.001); and that it is compatible with rearrangement of the HMGI-C and HMGI(Y) genes. The expression pattern and cellular localization of the immunoreactivity support the view that in biphasic lesions composed of a mixture of both stromal and epithelial cells, such as pulmonary chondroid hamartoma and endometrial polyps, the mesenchymal component is the site of the HMGI genetic alterations.
Tallini
G
G
Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510, USA. tallini@yale.edu
Vanni
R
R
Manfioletti
G
G
Kazmierczak
B
B
Faa
G
G
Pauwels
P
P
Bullerdiek
J
J
Giancotti
V
V
Van Den Berghe
H
H
Dal Cin
P
P
D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002881:Chromosomes, Human, Pair 12; D002896:Chromosomes, Human, Pair 6; D016889:Endometrial Neoplasms / Q000235:genetics; D005260:Female; D015321:Gene Rearrangement; D025741:HMGA1a Protein; D025743:HMGA2 Protein; D006222:Hamartoma / Q000235:genetics; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D007889:Leiomyoma / Q000235:genetics; D008067:Lipoma / Q000235:genetics; D008175:Lung Neoplasms / Q000235:genetics; D010641:Phenotype; D011127:Polyps / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014594:Uterine Neoplasms / Q000235:genetics
D025743:HMGA2 Protein; D006609:High Mobility Group Proteins; D014157:Transcription Factors; D025741:HMGA1a Protein