Mapping of the translocation breakpoints of primary pleomorphic adenomas and lipomas within a common region of chromosome 12

Tenascin-X and leukemia inhibitory factor receptor are down-regulated in leiomyoma compared with normal myometrium

OBJECTIVE

Uterine leiomyomas are the most common tumor of the uterus. But the molecular causes of uterine leiomyoma remain unclear. We conducted the current investigation in order to elucidate the molecular mechanisms in the development of uterine leiomyoma.

METHODS

We employed a new and accurate reverse transcription-polymerase chain reaction (RT-PCR) method that involved annealing control primers (ACPs) to identify the genes that are differently expressed in uterine leiomyoma.

RESULTS

Using 120 ACPs, we identified and sequenced 14 differently expressed genes (DEGs) in uterine leiomyoma compared with normal myometrium. Basic Local Alignment Search Tool (BLAST) searches were performed to examine the known functions of these genes associated with uterine leiomyoma. We confirmed differently expressed patterns in more cases using the RT-PCR method. We also detected two novel genes, Tenascin-X and Leukemia Inhibitory Factor Receptor (LIFR), which had not yet been reported to have any functions associated with uterine leiomyoma. RT-PCR confirmation shows that both of these two genes are down-regulated in uterine leiomyoma.

CONCLUSION

Our results suggest that Tenascin-X and LIFR may play a role in the development of uterine leiomyoma. Although further studies are required to establish the precise mechanisms with which these genes are involved in the genesis of uterine leiomyoma, the present research is significant in that it is the first study which detects down-regulated novel genes in uterine leiomyoma using the ACP system.

Hamartomatous angiolipoma of the parotid gland (sialoangiolipoma)

Mesenchymal tumors of the salivary glands are rare and mostly localized to the parotid gland. We report on the clinico-pathological features of a distinct parotid tumor occurred in a newborn, showing glandular structures admixed with mature lipocytes and blood vessels in variable proportions. This was a well-circumscribed and slowly growing nodule of the superficial parotid lobe, mostly reddish in color with white-yellowish striations. Microscopically, a distinct lobular architecture was evident, along with normal-appearing acinar and ductal structures with interposed loose fibrous stroma. The latter contained aggregates of mature lipocytes and variably sized blood vessels. The morphological features of the lesion reported herein recapitulate those of sialolipoma but also include the presence of a prominent vascular component intimately admixed with both the glandular and the adipose tissues. At variance with salivary lipoadenoma, the glandular component in the current case distinctly showed all the cellular components of normal salivary (serous) glands. In consideration of the young age of the patient, the minimal growth rate and the histological features of the lesion, we hypothesize a hamartomatous origin for this lesion and propose the designation of sialoangiolipoma.

Sarcoma

Sarcomas comprise a heterogeneous group of mesenchymal neoplasms. They can be grouped into 2 general categories, soft tissue sarcoma and primary bone sarcoma, which have different staging and treatment approaches. This review includes a discussion of both soft tissue sarcomas (malignant fibrous histiocytoma, liposarcoma, leiomyosarcoma, synovial sarcoma, dermatofibrosarcoma protuberans, angiosarcoma, Kaposi sarcoma, gastrointestinal stromal tumor, aggressive fibromatosis or desmoid tumor, rhabdomyosarcoma, and primary alveolar soft-part sarcoma) and primary bone sarcomas (osteosarcoma, Ewing sarcoma, giant cell tumor, and chondrosarcoma). The 3 most important prognostic variables are grade, size, and location of the primary tumor. The approach to a patient with a sarcoma begins with a biopsy that obtains adequate tissue for diagnosis without interfering with subsequent optimal definitive surgery. Subsequent treatment depends on the specific type of sarcoma. Because sarcomas are relatively uncommon yet comprise a wide variety of different entities, evaluation by oncology teams who have expertise in the field is recommended. Treatment and follow-up guidelines have been published by the National Comprehensive Cancer Network (www.nccn.org).

Expression patterns of the LPP-HMGA2 fusion transcript in pulmonary chondroid hamartomas with t(3;12)(q27 approximately 28;q14 approximately 15)

The high frequency of the t(3;12)(q27 approximately 28; q14 approximately 15) in lipomas and pulmonary chondroid hamartomas (PCHs) makes the HMGA2-LPP fusion gene the most frequent fusion gene in human tumors. We analyzed 11 PCHs with a t(3;12)(q27 approximately 28;q14 approximately 15) for the expression of the LPP-HMGA2 fusion transcript. In a previous study, all of these tumors were shown to express the HMGA2-LPP fusion transcript, composed of exons 1-3 of HMGA2 and exons 9-11 of LPP. In the present study, reverse transcriptase-polymerase chain reaction revealed the expression of the reciprocal fusion transcript in 8 of 11 cases. In all positive tumors, the reciprocal fusion transcripts had the same structure, namely, exons 1-8 of LPP and exons 4-5 of HMGA2 encoding a protein composed of the proline-rich region and the first LIM-domain of LPP and the acidic tail of HMGA2. To our knowledge, this is the first report of the expression of the LPP-HMGA2 fusion transcript in a series of PCHs. Its frequent occurrence in PCHs indicates the absence of a larger deletion of the LPP locus accompanying the translocation, such as has been described in a lipoma. Thus, based on this one finding, a role of LPP-HMGA2 in PCH should be considered.

Differential gene expression in liposarcoma, lipoma, and adipose tissue

Malignant transformation is thought to be associated with changes in the expression of a number of genes, and this alteration in gene expression is felt to be critical to the development of the malignant phenotype. Sarcomas represent a diverse group of tumors derived from cells of mesenchymal origin. Marked heterogeneity exists in the biological behavior of sarcomas, even within histologic subtypes of sarcomas. In an effort to better understand the biology of liposarcomas, gene expression in normal adipose tissue, lipomas, and liposarcomas was examined using the Affymetrix microarray technology. Differences in gene expression were quantified as the fold change in gene expression among the sample sets. Differences in gene expression among normal adipose tissue, lipomas, and liposarcomas were observed. In addition, genes expressed uniquely in liposarcoma among these and 18 other tissue sample sets were identified. Gene sets were devised that allowed the separation of liposarcomas from other samples, and most normal adipose tissue from most lipomas using the Eisen clustering software "Cluster." We conclude that differences in gene expression can be identified among different tumors derived from the adipocyte series. Such differences in gene expression may help differentiate among subtypes of sarcomas, and may also yield clues to the pathophysiology of this heterogeneous group of tumors.

Expression of the HMGA2-LPP fusion transcript in only 1 of 61 karyotypically normal pulmonary chondroid hamartomas

The HMGA2 gene has been found to be rearranged in a variety of benign solid tumors. However, in all tumor entities where aberrations of the corresponding chromosomal region have been found, a large percentage of tumors do not show any detectable cytogenetic deviation. Thus, the question arises whether or not in some of these cases, small subpopulations of tumor cells characterized by HMGA2 rearrangements exist. The existence of these populations would strongly suggest a secondary nature of the chromosomal aberrations. Herein, we have addressed this question by RT-PCR analyses of the HMGA2-LPP fusion resulting from t(3;12)(q27 approximately q28;q14 approximately q15) in a series of 61 pulmonary chondroid hamartomas (PCH) with an apparently normal karyotype. As a result, the HMGA2-LPP fusion transcript was amplified in only one of 61 PCH with a normal karyotype. In this case, fluorescence in situ hybridization analysis revealed a hidden chromosomal aberration. The absence of the HMGA2-LPP fusion in small populations of tumors with a normal karyotype suggests the primary nature of chromosomal rearrangements in the development of PCH affected by those aberrations.

Identification of differentially expressed genes in human uterine leiomyomas using differential display

In searching of differentially expressed genes in human uterine leiomyomas, differential display was used with twelve pairs of primers to compare human uterine leiomyomas with matched myometrium. False positives were eliminated by reverse Northern analysis. Positives were confirmed by Northern blot analysis.

RESULTS

Four of 69 cDNA fragments (3 up-regulated named L1, L2 and L3 and 1 down-regulated named M1 in leiomyoma) were confirmed by Northern analysis. Sequence comparison and Northern analysis proved that L1 is exactly the human ribosomal protein S19. It was present ubiquitously in 13 tissues tested but in various levels and even in different size. L1 was highly expressed in parotidean cystadenocarcinoma, pancreatic cancer and breast cancer examined. No mutations have been found in human uterine leiomyomas (n=6).

CONCLUSIONS

hRPS19 overexpression might be a universal signal in rapid cell growth tissues.

Cytogenetic analysis of a primary salivary gland myoepithelioma

Myoepithelioma, a rare benign salivary gland neoplasm, is a tumor composed entirely of myoepithelial cells. Unlike pleomorphic adenoma, these tumors lack any ductal epithelial differentiation, and manifest a minor stromal element. Previous cytogenetic and molecular genetic studies have mainly investigated pleomorphic adenomas and reported recurring specific chromosomal alterations at 8q12 and 12q13-q15 regions. The cell origin of these alterations, however, remains speculative. We report the cytogenetic analysis of a parotid myoepithelioma and discuss the putative origin for the cells with cytogenetic alterations. Our analysis shows 12q12 involved in a translocation with a previously unreported partner (1q), and nonrandom del(9)(q22.1q22.3) and del(13)(q12q22). Our results indicate that the myoepithelial cell is the source of those cells with chromosomal alterations, and that myoepithelioma shares 12q alterations reported in a subset of pleomorphic adenomas.

A fibroadenoma with a t(4;12) (q27;q15) affecting the HMGI-C gene, a member of the high mobility group protein gene family

An intracanalicular fibroadenoma of the breast showing a clonal chromosomal aberration t(4;12) (q27;q15) as the sole cytogenetic abnormality is described. In order to narrow down the breakpoint region on chromosome 12 on the molecular level we performed fluorescence in situ hybridization (FISH) analysis with a cosmid pool originating from a YAC-contig overspanning part of the region 12q14-15. We were able to narrow down the breakpoint to an approximately 230kb fragment belonging to the HMGI-C gene which maps within an area recently designated as MAR (Multiple Aberration Region). The chromosomal breakpoints of other frequent benign solid tumors, i.e. lipomas, uterine leiomyomas, and pleomorphic adenomas are clustered within the third intron of that gene.