Cancer Genetics and Cytogenetics最新文献

Most basal-like breast carcinomas are estrogen receptor negative, progesterone receptor negative, and cerb-B2/HER-2/neu negative—the so-called triple-negative breast carcinomas—with high epidermal growth factor receptor (EGFR) expression, which makes EGFR a target of treatment. We evaluated EGFR expression by immunohistochemistry (IHC) with two different clones (EGFR.31G7 and EGFR.25) and gene copy number by fluorescence in situ hybridization (FISH) with Locus specific identifier EGFR/CEP 7 dual probe in 62 triple-negative breast carcinomas. Any complete or incomplete membranous and/or cytoplasmic expression was regarded as IHC positive. Cases showing gene amplification (a ratio of EGFR gene to chromosome 7 of ≥2 or 15 copies per cell in ≥10% of cells) and high polysomy (≥4 copies in ≥40% of cells) were considered FISH positive. We detected EGFR.31G7 positivity in 38 of 62 cases (61.4%), which was composed of 12 of 62 (19.4%) cytoplasmic, 14 of 62 (22.6%) incomplete membranous, and 12 of 62 (19.4%) complete membranous staining. Among 38 of 49 (77.6%) EGFR.25-positive cases, 7 of 49 (14.3%) exhibited cytoplasmic, 10 of 49 (20.4%) exhibited incomplete membranous, and 21 of 49 (42.9%) exhibited complete membranous staining pattern. Ten of 62 (16.1%) FISH-positive cases were identified; 1 of 62 (1.6%) showed amplification, and the rest showed high polysomy. All FISH-positive cases were also found to be IHC positive (P = 0.01) by both EGFR clones. The amplified case displayed strong complete membranous staining with both clones. Among the high polysomic cases; 4 of 9 (44.4%) incomplete membranous, 4 of 9 (44.4%) complete membranous and 1 of 9 (11.1%) cytoplasmic expression of EGFR.31G7, and 6 of 8 (75%) complete membranous and 2 of 6 (25%) cytoplasmic expression of EGFR.25 were detected. Here, we report that membranous EGFR expression is associated with increased gene copy number (P = 0.035 for EGFR.31G7 and P = 0.026 for EGFR.25 clone). Because the markers to predict anti-EGFR treatment response in other system tumors such as EGFR mutation and amplification seem to be rare events in breast cancer, membranous staining pattern of EGFR might be the best way to decide the patient eligibility for anti-EGFR therapy.

Nasopharyngeal carcinoma (NPC) is one of the most common cancers in Malaysia, mainly occurring among the Chinese population. To detect common genetic alterations in NPC, we screened seven cases of NPC using the comparative genomic hybridization (CGH) technique. Before proceeding to the CGH technique, the tumors were first confirmed to consist of 75% tumor cells or more. In brief, the technique consists of binding tumor DNA with normal DNA and human Cot-1 DNA, which is then hybridized to normal metaphase spreads. The slides were then counterstained with 4,6 diamino-2-phenylindole (DAPI II) for detection. Analyses were performed using CGH software (Cytovision). We found genetic alterations in all seven NPC samples. The common chromosomal gains (57%, four cases) were found on chromosome arms 1q, 4p, 5, 7q, 11, 14p, 15q, 18p, and 21p, and common chromosomal losses (43%, three cases) were found on chromosome arm 16p. Our results showed chromosomal alterations in all seven NPC cases in the Malaysian population. This result provides the platform for further investigations to locate tumor suppressor genes and oncogenes at specific chromosomal regions in Malaysian NPC patients.

Tobacco smoke containing numerous derived chemical carcinogens is the main risk factor for urothelial carcinoma. These carcinogens can induce DNA damage leading to chromosomal instability, which plays a fundamental role in urothelial carcinogenesis. Possible mechanisms could be centrosomal aberrations, which cause defective spindles and may be responsible for genetic instability. We evaluated the effect of urine from never smokers (NS) and current smokers (CS) in concentrations of 0 to 50% on cell proliferation, chromosomes, centrosomes, and the spindle status of normal human dermal fibroblasts and normal human urothelial cells (UROtsa). After 2 weeks of urine treatment, cell cultures were analyzed by centrosome and spindle immunostaining and conventional cytogenetics. Effects were compared to results of untreated controls. Analysis of normal human dermal fibroblasts and UROtsa cells revealed that urine from CS induced higher values of centrosome aberrations in a dose-dependent and cell line-independent manner when compared to cultures treated with urine from NS and untreated controls. Centrosomal alterations correlated with spindle defects and an increase of sporadic chromosomal aberrations. The observations suggest a causative role of chemical carcinogens in urine from CS in the origin of centrosome and spindle defects in vitro leading to chromosomal instability and may be involved in urothelial carcinogenesis.

Fanconi Anemia (FA) is an inherited bone marrow failure syndrome characterized by congenital abnormalities, progressive marrow failure and predisposition to myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and solid tumors. The most common acquired chromosomal aberrations in FA patients are trisomy of 1q and monosomy of chromosome 7; the latter is known to be associated with poor prognosis. A few reports also suggest that gains of 3q are associated with progression to MDS–AML and overall poor prognosis. It is not uncommon for patients with Fanconi anemia to have easily detectable (oligoclonal) chromosomal alterations in their still normal (nonmalignant) marrow, which makes it even more challenging to determine the import of such alterations. We conducted a retrospective longitudinal analysis of fluorescent in situ hybridization (FISH) analysis for gains in 1q and 3q and for monosomy 7 and 7q deletions on 212 bone marrow samples from 77 children with FA treated at our institution between 1987 and 2007. Given the baseline increased chromosomal instability and defective DNA repair in patients with FA, which leads to unbalanced chromosomal aberrations such as deletions, insertions, and translocations, for the purpose of this analysis an abnormal clone was defined as ≥10% abnormal cells. Chromosome 3 and 7 aberrations were associated with increased risk of developing MDS–AML (P = 0.019 and P < 0.001 respectively), although the significance of chromosome 3 aberrations disappeared when different observation times were accounted for. Gain of 1q alone did not predict development of MDS–AML. In conclusion, children with FA should be followed closely with FISH analyses, because some of the clonal chromosomal abnormalities may be early indicators of progression toward MDS–AML and thus also of the need for hematopoietic stem cell transplantation.

Five laboratories in the Chronic Lymphocytic Leukemia (CLL) Research Consortium (CRC) investigated standardizing and pooling of fluorescence in situ hybridization (FISH) results as a collaborative research project. This investigation used fixed bone marrow and blood cells available from previous conventional cytogenetic or FISH studies in two pilot studies, a one-day workshop, and proficiency test. Multiple FISH probe strategies were used to detect 6q-, 11q-, +12, 13q-, 17p-, and IGH rearrangements. Ten specimens were studied by participants who used their own probes (pilot study 1). Of 312 FISH interpretations, 224 (72%) were true-negative, 74 (24%) true-positive, 6 (2%) false-negative, and 8 (3%) false-positive. In pilot study no. 2, each participant studied two specimens using identical FISH probe sets to control for variation due to probe sets and probe strategies. Of 80 FISH interpretations, no false interpretations were identified. At a subsequent workshop, discussions produced agreement on scoring criteria. The proficiency test that followed produced no false-negative results and 4% (3/68) false-positive interpretations. Interpretation disagreements among laboratories were primarily attributable to inadequate normal cutoffs, inconsistent scoring criteria, and the use of different FISH probe strategies. Collaborative organizations that use pooled FISH results may wish to impose more conservative empiric normal cutoff values or use an equivocal range between the normal cutoff and the abnormal reference range to eliminate false-positive interpretations. False-negative results will still occur, and would be expected in low-percentage positive cases; these would likely have less clinical significance than false positive results. Individual laboratories can help by closely following rigorous quality assurance guidelines to ensure accurate and consistent FISH studies in their clinical practice and research.

Unclassifiable lymphoma with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma is a new category of B-cell lymphoma appearing in the new World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. This lymphoma usually shows MYC rearrangements with non-IGH genes in the setting of a complex karyotype possibly involving BCL2 and, less frequently, BCL6 rearrangements. According to the presence of two or three rearrangements, these lymphomas are called double-hit lymphomas or triple-hit lymphomas (THL), respectively. Here we report two cases of THL with MYC, BCL2, and BCL6 rearrangements and t(3;8)(q27;q24) diagnosed in one center in the last two years.

We presente a case of acute lymphoblastic leukemia caused by ETV6 amplification. Although the cytogenetic result revealed complex karyotype, multicolor fluorescence in situ hybridization and high-resolution multicolor banding supported amplification of a gene on 12p13. Fluorescence in situ hybridization with ETV6 probe confirmed the amplification. ETV6 generally plays as tumor-suppressor gene in leukemia. Their expression is decreased or missed by deletion or mutation. Otherwise, ETV6 protein overexpression was verified in this case by immunohistochemistry. Any translocation or mutation involving ETV6 was not detected. This experience strongly supports the hypothesis that the amplification of ETV6 is a possible mechanism of leukeogenesis as oncogene.