Cancer Genetics and Cytogenetics

Editorial Board

2010-03-01

Overexpression of the novel human gene, UBE2Q2, in breast cancer

2010-03-01

Abstract: The ubiquitin–proteasome pathway facilitates the degradation of damaged proteins and regulates growth and stress response. This pathway is activated in various cancers, including breast cancer. We have previously reported that the novel human gene, UBE2Q2, is a putative ubiquitin-conjugating enzyme that is located on chromosome 15 and is overexpressed in tumor mass and invasive epithelium in head and neck squamous-cell carcinoma. Here, real-time polymerase chain reaction was used to investigate the expression levels of UBE2Q2 gene in a collection of 21 breast cancer tissues matched with normal adjacent counterparts. Immunohistochemistry and Western blot testing were also performed on formalin-fixed, paraffin-embedded tissue sections by using a rabbit polyclonal antibody that we generated against an amino acid sequence predicted from the DNA sequence of UBE2Q2 gene. In the 21 cases investigated, a high increase in the expression of UBE2Q2 mRNA was found in 8 breast cancers (38.1%), a moderately increased UBE2Q2 expression was observed in 7 cases (33.3%), and no significant changes were detected in 6 cases (28.6%) of tumor samples when compared with corresponding normal tissues. Consistently, a higher level of immunoreactivity for UBE2Q2 protein was detected in invasive epithelium of cancerous tissues when compared with that in the normal epithelium. Our data suggest that the novel human gene UBE2Q2 may have implications for pathogenesis of breast cancer and could be used in molecular diagnosis purposes in the future.

Fetal colon cell line FHC exhibits tumorigenic phenotype, complex karyotype, and TP53 gene mutation

2010-03-01

Abstract: Stable cell lines obtained by spontaneous immortalization might represent early stages of malignant transformation and be useful experimental models for studies of mechanisms of cancer development. The FHC (fetal human cells) cell line has been established from normal fetal colonic mucosa. Detailed characterization of this cell line and mechanism of spontaneously acquired immortality have not been described yet. Therefore, we characterized the FHC cell line in terms of its tumorigenicity, cytogenetics, and TP53 gene mutation analysis. FHC cells displayed capability for anchorage-independent growth in semisolid media in vitro and formed solid tumors after transplantation into SCID (severe combined immunodeficiency) mice. This tumorigenic phenotype was associated with hypotriploidy and chromosome number ranging from 66 to 69. Results of comparative genetic hybridization arrays showed that most chromosomes included regions of copy number gains or losses. Region 8q23∼8q24.3 (containing, e.g., MYC proto-oncogene) was present in more than 20 copies per nucleus. Moreover, we identified mutation of TP53 gene in codon 273; triplet CGT coding Arg was changed to CAG coding His. Expression of Pro codon 72 polymorphic variant of p53 was also detected. Mutation of TP53 gene was associated with abolished induction of p21Waf1/Cip1 and MDM-2 proteins and resistance to apoptosis after genotoxic treatment. Because of their origin from normal fetal colon and their relative resistance to the induction of apoptosis, FHC cells can be considered a valuable experimental model for various studies.

Molecular cytogenetic analysis of Korean patients with Waldenström macroglobulinemia

2010-03-01

Abstract: To compare the molecular cytogenetic characteristics between Waldenström macroglobulinemia (WM) and multiple myeloma (MM), we performed interphase fluorescent in situ hybridization (FISH) in Korean patients with WM and MM. Forty patients with WM and 132 patients with MM were enrolled onto the study. FISH was performed with seven different probes: 6q21, 6q23, CEP4, CEP9, immunoglobulin (IgH) breakapart, RB1 gene, and 1q25. Out of 22 WM patients, 4 (18%) had abnormal karyotypes, mainly structural changes on conventional karyotyping. After performing FISH for the available 29 cases, deletions of 6q23 and 6q21 were newly detected in 3 cases (10%). There was no other anomaly, including trisomy 4 in WM. No 6q deletion was observed in MM patients, but RB1 deletion was the most common change (45%), followed by IgH translocation (42%) and gain of 1q (38%). In conclusion, Korean WM patients had a low rate of 6q deletion (10%) and no trisomy 4.

Array comparative genomic hybridization analysis of adult acute leukemia patients

2010-03-01

Abstract: We have performed a retrospective array-based comparative hybridization (array-CGH) study on 41 acute leukemia samples [n=17 acute lymphoblastic leukemia (ALL) patients only at diagnosis, n=3 ALL patients both at diagnosis and relapse; n=20 acute myeloid leukemia (AML) patients only at diagnosis and n=1 AML patient both at diagnosis and relapse] using an Agilent 44K array. In addition to previously detected cytogenetic aberrations, we observed cryptic aberrations in 95% of ALL and 90.5% of AML cases. ALL-specific recurrent abnormalities were RB1 (n=3), PAX5 (n=4), and CDKN2B (n=3) deletions; AML-specific recurrent abnormalities were HOXA9 and HOXA10 (n=2) deletions and NOTCH1 duplication (n=2). Recurrent duplication of the ELK1 oncogene was observed in both ALL (n=2) and AML (n=3) cases. Our results demonstrate that oligo-array CGH (oaCGH) is an effective method for defining copy number alterations and identification of novel recurring unbalanced abnormalities. At least for now, however, the use of oaCGH for routine diagnosis still has some restrictions.

Homozygous deletion of the STK11/LKB1 locus and the generation of novel fusion transcripts in cervical cancer cells

Michael T. McCabe, Doris R. Powell, Wei Zhou, Paula M. Vertino — 2010-03-01

Abstract: The STK11/LKB1 gene encodes a ubiquitously expressed serine/threonine kinase that is mutated in multiple sporadic cancers including non-small cell lung carcinomas, pancreatic cancers, and melanomas. LKB1 plays a role in multiple cellular functions including cell growth, cell cycle progression, metabolism, cell polarity, and migration. To date, only a limited number of studies have assessed the status of LKB1 in cervical cancers. Herein, we investigate DNA methylation, DNA mutation, and transcription at the LKB1 locus in cervical cancer cell lines. We identified homozygous deletions of 25–85kb in the HeLa and SiHa cell lines. Deletion breakpoint analysis in HeLa cells revealed that the deletion resulted from an Alu-recombination-mediated deletion (ARMD) and generated a novel LKB1 fusion transcript driven by an uncharacterized CpG island promoter located ∼11kb upstream of LKB1. Although the homozygous deletion in SiHa cells removes the entire LKB1 gene and portions of the neighboring genes SBNO2 and c19orf26, this deletion also generates a fusion transcript driven by the c19orf26 promoter and composed of both c19orf26 and SBNO2 sequences. Further analyses of public gene expression and mutation databases suggest that LKB1 and its neighboring genes are frequently dysregulated in primary cervical cancers. Thus, homozygous deletions affecting LKB1 in cervical cancers may generate multiple fusion transcripts involving LKB1, SBNO2, and c19orf26.

MTHFR C677T and A1298C variant genotypes and the risk of microsatellite instability among Iranian colorectal cancer patients

2010-03-01

Abstract: Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the folate metabolic pathway. We aimed to test the hypothesis that C677T and A1298C variants of MTHFR predispose to microsatellite instable (MSI) colorectal cancer. We determined MTHFR genotypes in 175 sporadic colorectal cancer patients and a total of 231 normal controls in Shiraz, Southern Iran. Among the genotypes found in our samples, MTHFR CT and CT+TT were associated with increased risk for CRC incidence [odds ratio (OR)=2.4, 95% confidence interval (95%CI)=1.8–4.4; OR=2.4, 95%CI=1.6–3.6, respectively]. Double heterozygotes 677CT/1298AC and double homozygote 677TT/1298AA and 677CC/1298CC genotypes also showed a significantly increased risk of developing CRC compared with the wild-type 677CC/1298AA genotypes of the controls. Among the 151 tumors tested, 36 (23.8%) were MSI+. MSI was more common in proximal tumors (OR=10.4; 95%CI=3.9–27.8) and in smokers (OR=2.9; 95%CI=1.3–6.7). In a case–control comparison, the MTHFR 677CT+TT genotype was strongly associated with MSI (OR=2.6; 95%CI=1.3–5.3). Hypermethylation of mismatch repair genes was positively related with MSI incidence in these tumor series (P=0.00). Our data suggest that the MTHFR 677CT+TT variant genotype may be a risk factor for MSI+ cancer.

Mutations of NFKBIA in biopsy specimens from Hodgkin lymphoma

Xiaojian Liu, Hong Yu, Wentao Yang, Xiaoyan Zhou, Hongfeng Lu, Daren Shi — 2010-03-01

Abstract: To determine the possible alteration of the inhibitor κBα (HUGO-approved symbol, NFKBIA) gene in Chinese Hodgkin lymphoma (HL) patients, NFKBIA mRNA and protein expression in 22 primary HL patients were examined. Individual tumor cells were used for amplification to obtain the NFKBIA gene, and the polymerase chain reaction products were sequenced. Compared with reactive surrounding lymphocytes, inhibitor κBα protein (IκBα) expression was weaker in the cytoplasm of H-RS (Hodgkin and Reed–Sternberg) cells. NFKBIA mRNA was strongly expressed in H-RS cells from HL sections, and little was detected in the reactive surrounding lymphocytes. A total of 37.5% of the patients with HL had mutations in the NFKBIA gene. Some mutations possibly resulted in C-terminally truncated form of the IκBα. These data suggest that the impairment of the IκBα functions was produced during the pathogenesis of the tumor cell clone in Chinese HL patients.

Amplification and deletion of the ACHE and BCHE cholinesterase genes in sporadic breast cancer

2010-03-01

Abstract: Increasing evidence supports the involvement of acetylcholinesterase and butyrylcholinesterase in cell proliferation control and differentiation, reinforcing the hypothesis that these enzymes might have an influence in tumorigenesis. It has already been shown that the cholinesterase genes are structurally altered or aberrantly expressed in a variety of tumor types. In this study, amplifications and deletions in the ACHE and BCHE genes were investigated in sporadic breast tumors using real-time polymerase chain reaction and the relative quantification method. The majority of the tumor tissues showed a notable number of both deletions and amplifications: 65.7% and 22.9%, respectively, in BCHE and 45.7% and 31.4%, respectively, in ACHE. Deletion of the ACHE gene was significantly correlated with amplification of the protooncogene ERBB2. Tumor size was significantly higher when the ACHE gene was amplified, and the total number of alterations (amplifications plus deletions) of the BCHE gene was positively correlated with tumor malignancy grade.

High-resolution oligonucleotide array comparative genomic hybridization study and methylation status of the RPS14 gene in de novo myelodysplastic syndromes

2010-03-01

Abstract: In myelodysplastic syndromes (MDS), close to one half of patients do not have any visible karyotypic change. In order to study submicroscopic genomic alterations, we applied high-resolution array comparative genomic hybridization techniques (aCGH) in 37 patients with de novo MDS. Furthermore, we studied the methylation status of the RPS14 gene in 5q deletion (5q21.3q33.1) in 24 patients. In all, 21 of the 37 patients (57%) had copy number alterations. The most frequent copy number losses with minimal common overlapping areas were 5q21.3q33.1 (21%) and 7q22.1q33 (19%); the most frequent copy number gain was gain of the whole chromosome 8 (8%). Recurrent, but less frequent copy number losses were detected in two cases each: 11q14.1q22.1, 11q22.3q24.2, 12p12.2p13.31, 17p13.2, 18q12.1q12.2, 18q12.3q21.3, 18q21.2qter, and 20q11.23q12; the gains 8p23.2pter, 8p22p23.1, 8p12p21.1, and 8p11.21q21.2 were similarly found in two cases each. No homozygous losses or amplifications were observed. The RPS14 gene was not methylated in any of the patients.

Association of TP53 codon 72 polymorphism with cervical cancer risk in Chinese women

Pei Jiang, Jianxin Liu, Xiaoxi Zeng, Wen Li, Jianxin Tang — 2010-03-01

Abstract: Polymorphism at codon 72 of TP53, resulting in either the arginine (Arg) or proline (Pro) form of p53 (R72P), has been associated with the susceptibility to different cancers. To better understand the role of this polymorphism in cervical cancer etiology, we investigated the association between p53 R72P and cervical cancer risk in Chinese women from southern Han. Blood samples from 105 women with cervical cancer and from 140 female blood donors were collected. DNA from peripheral blood lymphocytes was extracted, and the exon 4 of TP53 was amplified by polymerase chain reaction and then digested by BstUI. We observed that the Arg/Arg genotype was significantly associated with an increased risk for cervical cancer [odds ratio (OR)=1.465, 95% confidence interval (95%CI)=1.04–2.138, P=0.02]. The relative frequency of each allele was 0.69 for Arg and 0.31 for Pro in patients with cervical cancer, and 0.60 for Arg and 0.40 for Pro in normal controls (P<0.05). Furthermore, we also found that the TP53 R72P polymorphism was not linked to tumor histologic type, histologic grade, lymph node metastases, and tumor size. These findings suggest that the TP53 codon 72 polymorphism may be implicated in cervical carcinogenesis, with the Arg/Arg genotype being associated with an increased susceptibility for this malignancy in the southern Chinese population.

Identification of a patient with 7q32 deletion–associated acute myeloid leukemia and an incidental t(8;14)

2010-03-01

Abstract: Constitutional activation of the MYC proto-oncogene resulting from a t(8;14) has been demonstrated in approximately 80% of Burkitt lymphoma patients, but only in one case of acute myeloid leukemia (AML). We report on a 59-year-old female diagnosed with minimally differentiated AML (M0). Chromosome analysis demonstrated both a 7q deletion and a t(8;14). Fluorescence in situ hybridization studies confirmed MYC/IGH fusion in 35% of nuclei, but the translocation was atypical due to lack of immunoglobulin heavy chain (IGH) gene disruption. Such an atypical fusion has never been reported, so the effect on MYC regulation due to proximity of IGH regulatory elements is unknown. Real-time polymerase chain reaction analysis demonstrated no increase in MYC expression (P = 0.12). These results suggest that this novel translocation does not result in dysregulation of MYC expression, so this is likely to be a coincidental, benign finding in this patient. This is yet another example of a classic cytogenetic abnormality observed on conventional chromosome analysis which has no functional significance.

Two distinct clonal populations in acute promyelocytic leukemia, one involving chromosome 17 and the other involving an isochromosome 17

2010-03-01

Abstract: Acute promyelocytic leukemia (APL) is characterized by a t(15;17)(q22;q21) rearrangement. Additional chromosomal rearrangements have been reported in 25–40% of APL patients. The most common abnormality involving chromosome 17 is ider(17). Here we report the case of a patient with APL with isochromosome 17q combined with ider(17), confirmed by fluorescence in situ hybridization. Cytogenetic data strongly suggest that the involvement of chromosomes 15 and 17 in translocation occurs after formation of the isochromosome 17. The case reported here presents the novel finding of two separate clonal events apparently occurring at the same time in an APL patient.

Paraganglioma in a 13-year-old girl: a novel SDHB gene mutation in the family?

2010-03-01

Paraganglioma (PGL) is a rare tumor that may be found in the abdomen, the thorax, or the head and neck region. Succinate dehydrogenase (SDH, or succinate-coenzyme Q reductase) was recognized as one of the key molecules playing a role in the pathogenesis of the tumor . An enzyme complex bound to the inner mitochondrial membrane, SDH is the only enzyme that participates in both the citric acid cycle and the mitochondrial electron transport chain. It is a heterotetramer divided into three domains: SDHA, the catalytic domain, SDHB, the electron transfer subunit; and SDHC and SDHD, the anchor subunits.

rs2981582 is associated with FGFR2 expression in normal breast

Chang Sun, Olufunmilayo I. Olopade, Anna Di Rienzo — 2010-03-01

Breast cancer is the most common cancer in women and is associated with genetic variants in critical genes and protein pathways. Several recent association studies have identified fibroblast growth factor receptor-2 (FGFR2), a gene involved in mammary gland development, as a novel gene for breast cancer risk and rs2981582, or its proxy single-nucleotide polymorphism (SNP), as a candidate SNP in various populations . Further studies suggest that two single-nucleotide polymorphism (SNP) (rs2981578 and rs7895676) in strong linkage disequilibrium (LD) with rs2981582 could influence enhancer activity by altering the Runt-related transcription factor 2 (Runx2) and/or CCAAT/enhancer-binding protein-β (C/EBPβ) binding affinity . rs2981582 was observed to be associated with FGFR2 expression in breast cancer tissues , accordingly. It is unknown, however, whether this correlation between genotype and mRNA levels is tissue-specific, and whether it is present also in normal breast tissue. Indeed, it is not unusual to observe differential gene expression in the same pathway between normal and carcinoma cells .

2010-03-01

Cancer Genetics and Cytogenetics

Editorial Board

Overexpression of the novel human gene, UBE2Q2, in breast cancer

Fetal colon cell line FHC exhibits tumorigenic phenotype, complex karyotype, and TP53 gene mutation

Molecular cytogenetic analysis of Korean patients with Waldenström macroglobulinemia

Array comparative genomic hybridization analysis of adult acute leukemia patients

Homozygous deletion of the STK11/LKB1 locus and the generation of novel fusion transcripts in cervical cancer cells

MTHFR C677T and A1298C variant genotypes and the risk of microsatellite instability among Iranian colorectal cancer patients

Mutations of NFKBIA in biopsy specimens from Hodgkin lymphoma

Amplification and deletion of the ACHE and BCHE cholinesterase genes in sporadic breast cancer

High-resolution oligonucleotide array comparative genomic hybridization study and methylation status of the RPS14 gene in de novo myelodysplastic syndromes

Association of TP53 codon 72 polymorphism with cervical cancer risk in Chinese women

Identification of a patient with 7q32 deletion–associated acute myeloid leukemia and an incidental t(8;14)

Two distinct clonal populations in acute promyelocytic leukemia, one involving chromosome 17 and the other involving an isochromosome 17

Paraganglioma in a 13-year-old girl: a novel SDHB gene mutation in the family?

rs2981582 is associated with FGFR2 expression in normal breast

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