Comparative genomic hybridization detects novel amplifications in fibroadenomas of the breast

Genetic differences between benign phyllodes tumors and fibroadenomas revealed through targeted next generation sequencing

Breast fibroepithelial lesions are biphasic tumors which comprise the common benign fibroadenomas (FAs) and the rarer phyllodes tumors (PTs). This study analyzed 262 (42%) conventional FAs, 45 (7%) cellular FAs, and 321 (51%) benign PTs contributed by the International Fibroepithelial Consortium, using a previously curated 16 gene panel. Benign PTs were found to possess a higher number of mutations, and higher rates of cancer driver gene alterations than both groups of FAs, in particular MED12, TERT promoter, RARA, FLNA, SETD2, RB1, and EGFR. Cases with MED12 mutations were also more likely to have TERT promoter, RARA, SETD2, and EGFR. There were no significant differences detected between conventional FAs and cellular FAs, except for PIK3CA and MAP3K1. TERT promoter alterations were most optimal in discriminating between FAs and benign PTs. Our study affirms the role of sequencing and key mutations that may assist in refining diagnoses of these lesions.

The genomic mutation spectrums of breast fibroadenomas in Chinese population by whole exome sequencing analysis

Fibroadenomas (FAs) are the most common fibroepithelial lesions and the most common benign tumors of the breast in women of reproductive age. Although MED12 mutations, an overwhelming majority of all mutations, and some other gene mutations have been found in FAs, the genomic landscapes of FAs are still not completely clear and the genomic mutation spectrums of FAs in Chinese population remains unknown. Here, by performing whole exome sequencing of 12 FAs and the corresponding normal breast tissues in Chinese Han population, we observed the somatic and germline landscapes of genetic alterations. We identified 16 recurrently mutated genes with 37 nonsynonymous or frameshift somatic mutations and 27 recurrent somatic copy number variants (CNVs). In these mutated genes, MED12 was the most common in FAs, harboring 6 nonsynonymous/frameshift somatic mutations and 1 CNV. In addition, 6 germline mutations of tumor susceptibility genes in 5 FAs were identified and the tumor mutational burden of the 5 FAs was significantly higher than the other 7 FAs without germline mutations. This study provides genomic mutation spectrums of FAs in Chinese population and expand the genetic spectrum of FAs.

Genome-wide association study using diversity outcross mice identified candidate genes of pancreatic cancer

To understand the genetic causes of pancreatic cancer (PC), we conducted a genome-wide association study (GWAS) using the diversity outbred (DO) mice population to identify susceptibility genes underlying 7,12-dimethylbenzanthraene (DMBA) induced PC. The phenotype studied was the percent PC lesion area in the DO mice population. We genotyped 7851 SNP markers specifically designed for DO mice across the whole mouse genome. Four susceptibility genes with P values exceeding the genome-wide threshold for percent PC lesion area (P < 2.37 × 10^-6) were identified, i.e., Epha4, Gpc5, Kcnj6, Arid1b. The most significant SNP of Gpc5 (UNC140360310) that is associated with PC lesion area in mice also significantly influences the Gpc5 expression, suggesting that this Gpc5 SNP exerts its role in PC through cis-regulating the gene expression of Gpc5. Together, our data supported that Gpc5 as a tumor suppressor gene involved in the etiology of PC.

Epstein-Barr virus infection and breast invasive ductal carcinoma in Egyptian women: A single center experience

BACKGROUND

A controversy of the role of Epstein-Barr virus (EBV) infection in breast carcinomas has been reported in the literature.

OBJECTIVES

We carried on this research to explore possible association between EBV infection and breast invasive ductal carcinoma (IDC) in Egyptian women attending our center.

STUDY DESIGN

This study carried out at Sohag university hospital on 84 paraffin embedded samples of breast tissue, of them 42 breast IDC as the case group and 42 breast fibroadenomas as the control group. Nested PCRand immunohistochemistry (IHC) done separately for all samples to identify the Epstein-Barr nuclear antigen-1 (EBNA-1) gene and EBV latent membrane protein-1 (LMP-1) respectively, in breast cancer cells and controls.

RESULTS

Specimen considered positive when both (EBNA-1) gene and LMP-1 were detected using PCR and IHC separately for the same sample, this was achieved by 10/42 (23.81%) of breast IDC (case group) and 6/42 (14.29%) of breast fibro-adenomas (control group) (P-value=0.4). Nodal involvement was the only parameter that demonstrated a significant statistical relationship with EBV presence in cancerous tissue with p-value=0.003.

CONCLUSION

Our research could not find a significant statistical association between EBV infection and breast IDC in Egyptian women attending our center, but, there might be an association between the existence of EBV and tumor aggressiveness.

The overexpression of glypican-5 promotes cancer cell migration and is associated with shorter overall survival in non-small cell lung cancer

Although the correlation between glypican-5 (GPC5) and lung cancer is well known, the effect of GPC5 expression on non-small cell lung cancer (NSCLC) survival remains to be determined. In the present study, GPC5 expression in A549, H3255, and SPC-A1 NSCLC cell lines was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis. GPC5 mRNA and protein expression levels were found to be higher in A549 and H3255 cells compared with SPC-A1 cells. The role of GPC5 in NSCLC cell migration was evaluated in vitro by shRNA-mediated knockdown or the overexpression of GPC5 through scratch and transwell assays. The mean migration rates of cancer cells transfected with pRNAT-shRNA-GPC5-1 were reduced compared with the controls in A549 (P<0.001) and H3255 (P=0.001), while the migration rate of SPC-A1 with GPC5 overexpression was higher than that of the control (P=0.001). The downregulation of GPC5 impeded the transmigration of A549 and H3255 while the upregulation of GPC5 expression promoted the transmembrane invasion of SPC-A1. Furthermore, a panel of formalin-fixed paraffin-embedded NSCLC tissues from 127 patients undergoing curative resection (stages I, II and III) between January, 2003 and December, 2008 were obtained in order to investigate the correlation between GPC5 expression and clinicopathological factors using immunohistochemical methods. The results demonstrated that high GPC5 expression levels in NSCLC were associated with respiratory symptoms in lung cancer diagnosis, poor differentiation, vascular invasion, regional lymph node metastasis and a higher TNM stage. Using the Kaplan-Meier method, NSCLC patients with high levels of GPC5 expression demonstrated a significantly shorter overall survival time compared with those with low GPC5 expression levels (median postsurgical survival time: 14.0 months vs. 59.0 months, P=0.001). GPC5 expression was also identified as an independent prognostic factor by Cox regression analysis [adjusted hazard ratio: 2.18; 95% confidence interval (CI): 1.35–3.52; P=0.001]. This study suggested that increased levels of GPC5 expression are a poor prognostic marker for NSCLC.

Chromosomal imbalances exclusively detected in invasive front area are associated with poor outcome in laryngeal carcinomas from different anatomical sites

Laryngeal squamous cell carcinoma (LSCC) is a malignant neoplasm exhibiting aggressive phenotype, high recurrence rate, and risk of developing second primary tumors. Current evidence suggests that cells in the invasive front of carcinomas have different molecular profiles compared to those in superficial areas. This study aimed to identify candidate genes in the invasive front and superficial cells from laryngeal carcinomas that would be useful as molecular markers. Invasive front and tumor surface cells of 32 LSCC were evaluated by high-resolution comparative genomic hybridization. Both CCND1 copy number gains and cyclin D1 protein expression were evaluated to confirm gains of 11q13.3. Losses of 3q26.2-q29 and 18q23 were confirmed by loss of heterozygosity analysis. The most frequent chromosomal alterations observed only in invasive front cells involved gains of 1p, 4q, and 9p and losses of 3p, 11p, 12p, 13q, 17q, 18p, 19q, 20q, 21q, and Xp. Gains of 11q13 were detected in both components from glottis and supraglottis but only in invasive front cells from transglottic tumors. Fluorescence in situ hybridization confirmed gains of CCND1/CPE11 in a subset of cases. In supraglottic tumors, cyclin D1 positivity was associated with distant metastasis (P = 0.0018) and with decreased disease-free survival (P = 0.042). Loss of heterozygosity at 3q26.2 and 18q23 were associated with lymph node involvement (P = 0.055) and worsened prognosis, respectively. In conclusion, this study revealed regions that could be targeted in the search for molecular markers in LSCC. Cyclin D1 may be useful as a prognostic marker in supraglottic tumors.

Immunohistochemical detection of glypican-5 in paraffin-embedded material: an optimized method for a novel research antibody

Glypican-5 (GPC5) is a cell surface heparan sulfate proteoglycan and 1 of 6 closely related members of the glypican family in mammals. Glypicans are predominantly expressed during development in cell-specific and tissue-specific contexts, and the expression of some is linked to developmental disorders and several visceral malignancies. We have previously shown that the region of amplification at 13q31.3 in a subset of rhabdomyosarcomas contains the GPC5 locus, and by copy number and gene expression analyses, that GPC5 is consistently expressed and upregulated in amplified tumors. As the immunohistochemical profile of GPC5 is untested, our aim was to optimize a commercially available anti-human GPC5 antibody for immunohistochemical use in formalin-fixed and paraffin-embedded (FFPE) tissue. Quantitative real-time polymerase chain reaction analyses of normal tissue samples indicated that the brain and testis highly expressed GPC5. High protein expression in these tissues and a cell line constructed to overexpress GPC5 were demonstrated by Western blotting. These normal tissues and the isogenic cell line were FFPE, and immunohistochemical expression of GPC5 was assessed using different methods of antigen retrieval, detection, and primary antibody concentration. The optimum conditions for detection were by heat-induced antigen retrieval, in sodium citrate buffer at pH 6. Enzyme-mediated retrieval did not produce effective detection, producing weaker, less well-localized GPC5 expression. We demonstrate that anti-human GPC5 antibody is amenable to use in FFPE tissue and with the optimized protocol we describe shows specific cellular localization and good staining intensity with minimal background staining.

Genetic variants and risk of lung cancer in never smokers: a genome-wide association study

BACKGROUND

Lung cancer in individuals who have never smoked tobacco products is an increasing medical and public-health issue. We aimed to unravel the genetic basis of lung cancer in never smokers.

METHODS

We did a four-stage investigation. First, a genome-wide association study of single nucleotide polymorphisms (SNPs) was done with 754 never smokers (377 matched case-control pairs at Mayo Clinic, Rochester, MN, USA). Second, the top candidate SNPs from the first study were validated in two independent studies among 735 (MD Anderson Cancer Center, Houston, TX, USA) and 253 (Harvard University, Boston, MA, USA) never smokers. Third, further replication of the top SNP was done in 530 never smokers (UCLA, Los Angeles, CA, USA). Fourth, expression quantitative trait loci (eQTL) and gene-expression differences were analysed to further elucidate the causal relation between the validated SNPs and the risk of lung cancer in never smokers.

FINDINGS

44 top candidate SNPs were identified that might alter the risk of lung cancer in never smokers. rs2352028 at chromosome 13q31.3 was subsequently replicated with an additive genetic model in the four independent studies, with a combined odds ratio of 1.46 (95% CI 1.26-1.70, p=5.94x10(-6)). A cis eQTL analysis showed there was a strong correlation between genotypes of the replicated SNPs and the transcription level of the gene GPC5 in normal lung tissues (p=1.96x10(-4)), with the high-risk allele linked with lower expression. Additionally, the transcription level of GPC5 in normal lung tissue was twice that detected in matched lung adenocarcinoma tissue (p=6.75x10(-11)).

INTERPRETATION

Genetic variants at 13q31.3 alter the expression of GPC5, and are associated with susceptibility to lung cancer in never smokers. Downregulation of GPC5 might contribute to the development of lung cancer in never smokers.

FUNDING

US National Institutes of Health; Mayo Foundation.

RHEB expression in fibroadenomas of the breast

Although fibroadenoma is one of the most common types of benign breast tumor, genes specific to the tumor have not been identified. Microarrays were used to identify differentially expressed genes between fibroadenoma and infiltrating ductal carcinoma. The comparative expression of one of the identified genes, RAS homolog enriched in the brain (RHEB), was further explored using reverse transcriptase-polymerase chain reaction (RT-PCR). Microarray analysis was performed on tissue samples from five patients with fibroadenoma. In the fibroadenoma samples, the genes HDAC1, ROS1, TNFRSF10A, WASP2, TYRP1, WEE1, and RHEB were expressed at levels more than twofold higher than in the normal tissues. RT-PCR for RHEB indicated increased expression of RHEB in fibroadenoma compared to breast cancer. When studied with real-time PCR, the average RHEB/beta-actin ratio in fibroadenoma samples was 1.99, 2.46-fold greater than the average RHEB/beta-actin ratio in breast carcinoma of 0.81 (P < 0.01). Immunohistochemistry and PCR followed by microdissection shows increased expression of RHEB in epithelial cells compared to the stromal cells of fibroadenoma. Therefore, RHEB could be used cytopathologically to distinguish fibroadenoma from malignant breast carcinomas as a secondary diagnostic tool.

Role for amplification and expression of glypican-5 in rhabdomyosarcoma

Overexpression of genes, through genomic amplification and other mechanisms, can critically affect the behavior of tumor cells. Genomic amplification of the 13q31-32 region is reported in many tumors, including rhabdomyosarcomas that are primarily pediatric sarcomas resembling developing skeletal muscle. The minimum overlapping region of amplification at 13q31-32 in rhabdomyosarcomas was defined as containing two genes: Glypican-5 (GPC5) encoding a cell surface proteoglycan and C13orf25 encompassing the miR-17-92 micro-RNA cluster. Genomic copy number and gene expression analyses of rhabdomyosarcomas indicated that GPC5 was the only gene consistently expressed and up-regulated in all cases with amplification. Constitutive overexpression and knockdown of GPC5 expression in rhabdomyosarcoma cell lines increased and decreased cell proliferation, respectively. A correlation between expression levels of nascent pre-rRNA and GPC5 (P = 0.001), but not a C13orf25 transcript containing miR-17-92, in primary samples supports an association of GPC5 with proliferative capacity in vivo. We show that GPC5 increases proliferation through potentiating the action of the growth factors fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and Wnt1A. GPC5 enhanced the intracellular signaling of FGF2 and HGF and altered the cellular distribution of FGF2. The mesoderm-inducing effect of FGF2 and FGF4 in Xenopus blastocysts was also enhanced. Our data are consistent with a role of GPC5, in the context of sarcomagenesis, in enhancing FGF signaling that leads to mesodermal cell proliferation without induction of myogenic differentiation. Furthermore, the properties of GPC5 make it an attractive target for therapeutic intervention in rhabdomyosarcomas and other tumors that amplify and/or overexpress the gene.

Genome-wide analysis for loss of heterozygosity in primary and recurrent phyllodes tumor and fibroadenoma of breast using single nucleotide polymorphism arrays

Phyllodes tumors of the breast are biphasic stromal and epithelial tumors histologically similar to benign fibroadenomas, but with a neoplastic stromal component. In contrast to fibroadenoma, phyllodes tumors can recur and be locally aggressive or be malignant. This study uses SNP array analysis to present a genome-wide map of loss of heterozygosity (LOH) in a cohort of phyllodes tumors and fibroadenomas. LOH is frequent and sometimes extensive in phyllodes tumors, but is rarely seen in fibroadenomas. There is heterogeneity between phyllodes tumors of different patients and no one LOH marker identifies a majority of these lesions. However, a subset of LOH loci occur in multiple cases of phyllodes tumors and are not found in fibroadenomas. Primary phyllodes tumors and paired recurrences from the same patient share common regions of LOH. In contrast, metachronous fibroadenomas from the same patient have different LOH patterns with no indication of a shared origin. Specific LOH loci may be associated with pathologic progression in recurrent phyllodes tumors. In a single case of phyllodes tumor containing a malignant epithelial component the malignant epithelium and stroma partially share an LOH genotype, suggesting a common precursor cell for the biphasic malignant components.

The molecular genetics of breast cancer: The contribution of comparative genomic hybridization

Comparative genomic hybridization (CGH) has been the technique of choice over the last 10 years for mapping DNA copy number changes in human tumors. Here we review the literature to demonstrate how CGH has contributed to the comprehension of molecular aspects of breast tumorigenesis. At least two distinct molecular pathways of breast cancer have been characterized that show a strong correlation with histological grade. It seems that grade I invasive ductal carcinomas (IDCs) arise from well-differentiated ductal carcinoma in situ (DCIS), whereas grade III IDCs come from poorly differentiated DCIS. In addition, dedifferentiation from a low- to a high-grade breast cancer has proven an unlikely phenomenon. CGH has been instrumental in dissecting distinct molecular pathways toward breast malignancy and in establishing a direct relationship between genotype and clinical pathological features.

DUAL SPECIFICITY PROTEIN PHOSPHATASES: Therapeutic Targets for Cancer and Alzheimer's Disease

The complete sequencing of the human genome is generating many novel targets for drug discovery. Understanding the pathophysiological roles of these putative targets and assessing their suitability for therapeutic intervention has become the major hurdle for drug discovery efforts. The dual-specificity phosphatases (DSPases), which dephosphorylate serine, threonine, and tyrosine residues in the same protein substrate, have important roles in multiple signaling pathways and appear to be deregulated in cancer and Alzheimer's disease. We examine the potential of DSPases as new molecular therapeutic targets for the treatment of human disease.

Lack of DNA copy number alterations revealed with comparative genomic hybridization in fibroadenomas of the breast

There are very few studies reporting DNA copy number changes in fibroadenomas of the breast. Using comparative genomic hybridization, we analyzed 20 paraffin-embedded samples of fibroadenomas of the breast from patients with no familial or previous history of breast cancer. No alterations in the DNA copy number were observed in any of the tumors analyzed, regardless of the chromosomal alterations observed using conventional cytogenetic analysis. We discuss our results and compare them to other reports on fibroadenomas.

Application of comparative genomic hybridization in search for genetic aberrations in fibroadenomas of the breast

We applied a comparative genomic hybridization (CGH) technique to paraffin-embedded tissue samples taken from fibroadenomas, benign breast tumors, to detect possible numerical and unbalanced genetic changes. We compared the results to those from previous cytogenetic studies of fibroadenomas. In concurrence with previous cytogenetic studies of fibroadenomas, we detected genetic aberrations in chromosomes 4-6, 8-13, 16, 18, 19, 20, and 22. In addition, with the CGH technique we were able to find two new aberrations, 15q+ and 16p-. Because these aberrations have also been reported to be present in breast cancer, the importance of this finding is yet to be determined.

Compilation of published comparative genomic hybridization studies

The power of comparative genomic hybridization (CGH) has been clearly proven since the first paper appeared in 1992 as a tool to characterize chromosomal imbalances in neoplasias. This review summarizes the chromosomal imbalances detected by CGH in solid tumors and in hemopathies. In May of 2001, we took a census of 430 articles providing information on 11,984 cases of human solid tumors or hematologic malignancies. Comparative generic hybridization has detected a number of recurrent regions of amplification or deletion that allows for identification of new chromosomal loci (oncogenes, tumor suppressor genes, or other genes) involved in the development, progression, and clonal evolution of tumors. When CGH data from different studies are combined, a pattern of nonrandom genetic aberrations appears. As expected, some of these gains and losses are common to different types of pathologies, while others are more tumor-specific.

Comparative genomic hybridization analysis of benign and invasive male breast neoplasms

Comparative genomic hybridization (CGH) analysis was performed for the identification of chromosomal imbalances in two benign gynecomastias and one malignant breast carcinoma derived from patients with male breast disease and compared with cytogenetic analysis in two of the three cases. CGH analysis demonstrated overrepresentation of 8q in all three cases. One case of gynecomastia presented gain of 1p34.3 through pter, 11p14 through q12, and 17p11.2 through qter, and loss of 1q41 through qter and 4q33 through qter. The other gynecomastia presented del(1)(q41) as detected by both cytogenetic and CGH analysis. CGH analysis of the invasive ductal carcinoma confirmed a gain of 17p11.2 through qter previously detected by cytogenetic analysis. These regions showed some similarity in their pattern of imbalance to the chromosomal alterations described in female and male breast cancer.