Characterization of a novel breast carcinoma xenograft and cell line derived from a BRCA1 germ-line mutation carrier

A human tumor xenograft (L56Br-X1) was established from a breast cancer axillary lymph node metastasis of a 53-year-old woman with a BRCA1 germ-line nonsense mutation (1806C>T; Q563X), and a cell line (L56Br-C1) was subsequently derived from the xenograft. The xenograft carries only the mutant BRCA1 allele and expresses mutant BRCA1 mRNA but no BRCA1 protein as determined by immunoprecipitation or Western blotting. The primary tumor, lymph node metastasis, and xenograft were hypodiploid by DNA flow cytometry, whereas the cell line displayed an aneuploidy apparently developed via polyploidization. Cytogenetic analysis, spectral karyotyping, and comparative genomic hybridization of the cell line revealed a highly complex karyotype with numerous unbalanced translocations. The xenograft and cell line had retained a somatic TP53 missense mutation (S215I) originating from the primary tumors, as well as a lack of immunohistochemically detectable expression of steroid hormone receptors, epidermal growth factor receptor, human epidermal growth factor receptor 2 (HER-2), and keratin 8. Global gene expression analysis by cDNA microarrays supported a correlation between the expression profiles of the primary tumor, lymph node metastasis, xenograft, and cell line. We conclude that L56Br-X1 and L56Br-C1 are useful model systems for studies of the pathogenesis and new therapeutic modalities of BRCA1-induced human breast cancer.     

Clonal structural chromosome aberrations in fibrous dysplasia

Cytogenetic analysis of short-term cultures from a case of monostotic fibrous dysplasia in a 14-year-old girl revealed multiple clonal structural rearrangements with evidence of clonal evolution. The karyotype was 46,XX,del(3)(q27),add(10)(q22), add(12)(p13)/46,idem,t(3;8)(p21;q13),add(10)(q26),der(15)del(15)(q15q22)ins(15;?)(q15;?)/46,idem,-X, + 2,t(3;8),add(10),der(15). The finding of clonal structural aberrations suggests that fibrous dysplasia is a neoplastic lesion which develops as the result of somatic mutations.     

Chromosome analysis of 20 breast carcinomas: Cytogenetic multiclonality and karyotypic-pathologic correlations

Short-term cultures from 20 breast carcinomas were analyzed cytogenetically. A normal female chromosome complement was found in 4 cases. Clonal chromosome aberrations were detected in 16 tumors. In 10 tumors, multiple cytogenetic clones were found; in 2 cancers the clones were related, reflecting clonal evolution, but in the remaining 8 tumors the clones were cytogenetically unrelated, indicating clonal heterogeneity in the origin of the tumor parenchyma. Correlation analysis between karyotypic and pathologic parameters indicated that cases with complex karyotypes and/or cytogenetically unrelated clones, when compared with cases with a single simple karyotypic abnormality, were generally of higher histologic malignancy grade, had more mitoses in the histologic sections, and also more often had carcinoma in situ lesions in the same breast. © 1993 Wiley-Liss, Inc.     

Frequent rearrangement of chromosomal bands 1p22 and 11q13 in squamous cell carcinomas of the head and neck

We report the finding of clonal structural chromosome abnormalities in short-term cultures from 15 squamous cell carcinomas of the head and neck region. When the distribution of chromosomal breakpoints in these 15 tumors and in the 16 head and neck carcinomas previously described are assessed, a marked clustering is seen at bands 1p22 and 11q13, which are rearranged in eight and nine tumors, respectively. No other band was involved in aberrations in more than five tumors. Cytogenetic evidence of gene amplification was seen in four tumors, three times in the form of homogeneously staining regions (twice located in 11q13), and in one tumor as double minutes. Among the candidate genes for such amplification are BCLI, INT2, and HSTI, all of which map to 11q13, and NRAS, which maps to 1p22. All these oncogenes have previously been shown to be amplified in subsets of head and neck carcinomas. We conclude that bands 1p22 and 11q13 are nonrandomly involved in chromosomal rearrangements in head and neck carcinomas and suggest that activation of oncogenes located in these bands may proceed via cytogenetic mechanisms.     

Cytogenetic and molecular genetic analyses of endometrial stromal sarcoma: nonrandom involvement of chromosome arms 6p and 7p and confirmation of JAZF1/JJAZ1 gene fusion in t(7;17)

Endometrial stromal sarcomas (ESS) are rare neoplasms with the capacity both to invade the myometrium locally and to give rise to extrauterine metastases. Cytogenetic abnormalities have been reported in 22 cases of ESS, mostly involving rearrangements of chromosomes 6, 7, and 17. The most characteristic translocation of this tumor type, t(7;17)(p15 approximately p21;q12 approximately q21), was recently shown to generate a JAZF1/JJAZ1 fusion gene. We report three additional cases of ESS with abnormal karyotypes, whose interpretation was based on the combined analysis by conventional cytogenetics and cross-species color banding FISH (RxFISH). The combination of G-banding and RxFISH in every case gave additional information beyond that obtained by either technique alone, determining the identity of even complex inter- as well as intrachromosomal rearrangements. In one of the three tumors, a t(7;17) was seen; molecular genetic studies identified the JAZF1/JJAZ1 fusion gene in this case. Two tumors had aberrations that included structural changes of chromosome arms 6p and 7p. Evidently, karyotypic, and hence pathogenetic, heterogeneity exists for tumors classified as endometrial stromal sarcomas based on their phenotypic features.     

Effect of a new synthetic serum replacement on insulin and somatostatin secretion from isolated rat pancreatic islets in long-term culture

Summary Serum contains insulin degrading components. We have evaluated the insulin and somatostatin secretion from isolated rat pancreatic islets during a 2-wk culture period using three different serum-containing media, and one serum-free medium with a synthetic serum replacement. Islets incubated in serum-free medium elicited significantly higher daily insulin and somatostatin secretions than islets incubated in the serum-containing media. After a 2-wk culture period, islets from the serum-free medium secreted significantly more insulin and somatostatin than islets cultured in other media when stimulated with 25 mmol/liter glucose together with 15 mmol/liter theophylline. We conclude that the serum-free medium is superior for long-term culture of rat pancreatic islets.     

Marginal zone and germinal center development in the spleens of neonatally thymectomized and nonthymectomized young rats

Spleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus. In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium-sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity. Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed. The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical age.     

Near-haploid clones in a malignant fibrous histiocytoma

Near-haploid solid tumors are very rare. In a storiform-pleomorphic malignant fibrous histiocytoma (MFH) of bone, we found three cell populations: one with a near-haploid, a second with a near-diploid, and a third with a near-tetraploid chromosome number. The near-haploid cells had few structural rearrangements: i(12p) and t(13q21q) in one clone, and these two and an additional t(19;?)(p11;?) in another clone. One structurally normal copy of all chromosomes was also present, except that the only chromosome 13 was involved in the t(13q21q). There were also two near-diploid clones, one without the t(19;?) and one with a single copy of this derivative chromosome. This is the first MFH reported to have a near-haploid modal chromosome number, and also the first tumor with i(12p) among bone and soft tissue tumors.     

Trisomy 5 and loss of the Y chromosome as the sole cytogenetic anomalies in a cavernous hemangioma/angiosarcoma

Cytogenetic analysis of a cavernous hemangioma with transition to angiosarcoma revealed the mosaic karyotype 47, XY,+5/46, X,-Y,+5/45, X,-Y/46, XY. No cytogenetically analyzed hemangiomas or angiosarcomas have been reported before.