Gene expression profile of an adenomyoepithelioma of the breast with a reciprocal translocation involving chromosomes 8 and 16

Talin‑1 interaction network in cellular mechanotransduction (Review)

The mechanical signals within the extracellular matrix (ECM) regulate cell growth, proliferation and differentiation, and integrins function as the hub between the ECM and cellular actin. Focal adhesions (FAs) are multi‑protein, integrin‑containing complexes, acting as tension‑sensing anchoring points that bond cells to the extracellular microenvironment. Talin‑1 serves as the central protein of FAs that participates in the activation of integrins and connects them with the actin cytoskeleton. As a cytoplasmic protein, Talin‑1 consists of a globular head domain and a long rod comprised of a series of α‑helical bundles. The unique structure of the Talin‑1 rod domain permits folding and unfolding in response to the mechanical stress, revealing various binding sites. Thus, conformation changes of the Talin‑1 rod domain enable the cell to convert mechanical signals into chemical through multiple signaling pathways. The present review discusses the binding partners of Talin‑1, their interactions, effects on the cellular processes, and their possible roles in diseases.

Adenomyoepithelial tumors of the breast: molecular underpinnings of a rare entity

Adenomyoepitheliomas (AMEs) of the breast are uncommon and span the morphologic spectrum of benign, atypical, in situ, and invasive forms. In exceptionally rare cases, these tumors metastasize to regional lymph nodes or distant sites. In the era of genomic characterization, data is limited regarding AMEs. The aim of this study was to provide insight into the molecular underpinnings of a spectrum of AMEs. Seven cases of AMEs of the breast (benign-1, atypical-2, in situ-1, invasive-3) were identified in our files. The seven samples were interrogated using the Oncomine Comprehensive Assay v3 (ThermoFisher). Two atypical AMEs and the malignant in situ AME harbored the same gain-of-function PIK3CA mutation. The malignant in situ AME also showed EGFR amplification, not described previously. Both a benign AME and a malignant invasive AME shared the same gain-of-function AKT1 variant. The benign AME also showed a GNAS mutation. Moreover, the same gain-of-function HRAS mutation was present in an atypical AME and a malignant invasive AME. We also identified co-occurring HRAS and PIK3CA mutations in an ER-positive atypical AME, which has not been previously described. No fusion drivers were detected. We describe the molecular characteristics of the spectrum of AME tumors of the breast, which harbor alterations in the PI3K/AKT pathway. Our findings are clinically relevant with respect to the current options of targeted therapy in the rare instances where malignant AME tumors of the breast progress.

Recurrent hotspot mutations in HRAS Q61 and PI3K-AKT pathway genes as drivers of breast adenomyoepitheliomas

Adenomyoepithelioma of the breast is a rare tumor characterized by epithelial−myoepithelial differentiation, whose genetic underpinning is largely unknown. Here we show through whole-exome and targeted massively parallel sequencing analysis that whilst estrogen receptor (ER)-positive adenomyoepitheliomas display PIK3CA or AKT1 activating mutations, ER-negative adenomyoepitheliomas harbor highly recurrent codon Q61 HRAS hotspot mutations, which co-occur with PIK3CA or PIK3R1 mutations. In two- and three-dimensional cell culture models, forced expression of HRAS^Q61R in non-malignant ER-negative breast epithelial cells with or without a PIK3CA^H1047R somatic knock-in results in transformation and the acquisition of the cardinal features of adenomyoepitheliomas, including the expression of myoepithelial markers, a reduction in E-cadherin expression, and an increase in AKT signaling. Our results demonstrate that adenomyoepitheliomas are genetically heterogeneous, and qualify mutations in HRAS, a gene whose mutations are vanishingly rare in common-type breast cancers, as likely drivers of ER-negative adenomyoepitheliomas.

Adenomyoepithelioma is a rare tumor of the breast with an unknown genetic basis. Here the authors perform a genomic analysis of adenomyoepitheliomas revealing that their repertoire of somatic mutations vary according to the estrogen receptor (ER) status, and that ER-negative tumors harbor recurrent mutations in HRAS and PI3K pathway genes.

Complex Chromosomal Rearrangements in B-Cell Lymphoma: Evidence of Chromoanagenesis? A Case Report

Genomic instability is a well-known hallmark of cancer. Recent genome sequencing studies have led to the identification of novel phenomena called chromothripsis and chromoanasynthesis in which complex genomic rearrangements are thought to be derived from a single catastrophic event rather than by several incremental steps. A new term chromoanagenesis or chromosomal rebirth was coined recently to group these two one-step catastrophic events together. These phenomena suggest an evolutionary modality for cancer cells to circumvent individual mutational events with one simultaneous shattering of chromosomes resulting in the random reassembling of segmented genetic material to form complex derivative chromosomes. We report a case of possible chromoanagenesis in a patient with diffuse large B-cell lymphoma. Chromosome analysis from the biopsy showed a complex karyotype with multiple numerical and structural rearrangements including a translocation of chromosomes 3 and 7 involving the BCL6 gene region, with the derivative chromosome further rearranging with chromosomes 14, 7, and 22 with involvement of the IGH gene region. Fluorescence in situ hybridization studies confirmed these findings. Chromosomal microarray studies showed multiple complex copy number variations including a chromosome 12 abnormality, the complexity of which appears to suggest the phenomenon of chromoanagenesis. Our case further illustrates that lymphomagenesis can be complex and may arise from a catastrophic event resulting in multiple complex chromosome rearrangements.

[Adenomyoepithelioma with dominant myoepithelial contingent of the breast: A case report and literature review]

We report a case of adenomyoepithelioma with predominant myoepithelial quota, a rare tumor of the breast due to proliferation of epithelial and myoepithelial cells in a patient of 71 years. This lesion, with difficult radiological and pathological diagnosis (biopsy) in the initial stage of the treatment, should benefit from surgical resection in healthy margin. In fact, this tumor is evolving in most cases on a benin mode, but cases of local or metastatic recurrences were reported. Histological and immunohistochemical arguments are important to reach the final diagnosis.

Deleted in liver cancer-1 inhibits cell growth and tumorigenicity in human pancreatic cancer

Deleted in liver cancer-1 (DLC-1) has been isolated from primary hepatocellular carcinoma and demonstrated to be a potential tumor suppressor gene. The aim of the present study was to observe the effect of the DLC-1 gene on pancreatic cancer cell growth and evaluate the feasibility of using the DLC-1 gene in gene therapy for pancreatic cancer. A recombinant plasmid (pcDNA3.1/DLC-1) was transfected into PANC-1 cells by liposomes and then the pre-established human PANC-1 pancreatic carcinoma cells were injected into athymic nude mice via the tail vein. The results showed that the overexpression of DLC-1 in the PANC-1 cells inhibited cell proliferation in vitro, while the act of introducing DLC-1 reduced tumorigenicity in the nude mice. The findings suggest that DLC-1 may have an effect on the pathogenesis of pancreatic cancer. The DLC-1 gene may be a promising target in gene therapy for pancreatic cancer.

Adenomyoepithelioma of the breast: a review stressing its propensity for malignant transformation

This review describes the classification, clinical presentation, pathological features and clinical behaviour of adenomyoepithelioma (AME) of the breast. It is based on an extensive review of the literature and study of a collection of cases built up over a 17-year period at the British Columbia Cancer Agency. The diversity of the morphology encountered in both benign and malignant AME is described. The behaviour of malignant AME seems to be related to the grade of the malignant component.

Fusion of HMGA2 to COG5 in uterine leiomyoma

Uterine leiomyomas are smooth muscle tumors most commonly seen in middle-aged women. Approximately 10% of these tumors contain rearrangements of the chromatin-remodeling gene HMGA2 at the chromosome band 12q14.3. Herein, we report on a uterine leiomyoma with a novel HMGA2 fusion gene. A 44-year-old woman presented with a 20-cm mass uterine leiomyoma. From a histological standpoint, the tumor exhibited extensive hyalinization, very low mitotic activity (<1/10 HPH), and no cytologic atypia. Smooth muscle differentiation was confirmed by the expression of smooth muscle actin and desmin. Standard cytogenetic analysis showed the reciprocal translocation t(7;12)(q31.2;q14.3). Fluorescence in situ hybridization analysis confirmed a balanced rearrangement of the HMGA2 locus in 80% of the cells. 3'RACE reverse-transcription polymerase chain reaction identified the fusion of HMGA2 exon 4 to the COG5 locus on 7q31 (component of oligomeric golgi complex 5 isoform). The fusion sequence is predicted to encode a 96-amino acid chimeric protein that retains all three DNA-binding domains (AT hooks) of HMGA2, but that is shorter than the original HMGA2 protein. Since the general structure of the fusion gene is similar to other previously described HMGA2 fusions, its biologic activity is predicted to be likely similar.

DLC-1:a Rho GTPase-activating protein and tumour suppressor

The deleted in liver cancer 1 (DLC-1) gene encodes a GTPase activating protein that acts as a negative regulator of the Rho family of small GTPases. Rho proteins transduce signals that influence cell morphology and physiology, and their aberrant up-regulation is a key factor in the neoplastic process, including metastasis. Since its discovery, compelling evidence has accumulated that demonstrates a role for DLC-1 as a bona fide tumour suppressor gene in different types of human cancer. Loss of DLC-1 expression mediated by genetic and epigenetic mechanisms has been associated with the development of many human cancers, and restoration of DLC-1 expression inhibited the growth of tumour cells in vivo and in vitro. Two closely related genes, DLC-2 and DLC-3, may also be tumour suppressors. This review presents the current status of progress in understanding the biological functions of DLC-1 and its relatives and their roles in neoplasia.

Cytogenetic and molecular studies of an unusual case of multiple primary alveolar rhabdomyosarcomas: low-level chromosomal instability and reciprocal translocation t(6;11)

Cytogenetic and molecular studies have shown that approximately 80% of cases of alveolar rhabdomyosarcoma (ARMS) have consistent chromosomal translocation of either t(2;13) or t(1;13), resulting in either PAX3-FKHR or PAX7-FKHR gene fusions. However, 20% of the cases diagnosed histologically are negative for these fusion genes. The clinical and pathological properties of the so-called fusion gene negative tumors remain to be defined. We present an unusual case of a 7-year-old boy who developed three separate primary ARMS over a 5-year period, with the first tumor diagnosed at the age of 12 months. The tumors were negative for the characteristic translocations, t(2;13) or t(1;13), but showed evidence of low-level chromosomal instability and a reciprocal chromosomal translocation t(6;11)(q27;q13). PCR amplification of the p53 gene, exons 2-11, followed by DNA sequencing did not detect any germline p53 mutation. These clinical and cytogenetic features have not been reported previously in ARMS. The findings suggest that cytogenetic abnormalities of chromosome 6 may be associated with the development of early onset multiple ARMS in a subgroup of pediatric patients as seen in this case.

Generalization of DNA microarray dispersion properties: microarray equivalent of t-distribution

Background

DNA microarrays are a powerful technology that can provide a wealth of gene expression data for disease studies, drug development, and a wide scope of other investigations. Because of the large volume and inherent variability of DNA microarray data, many new statistical methods have been developed for evaluating the significance of the observed differences in gene expression. However, until now little attention has been given to the characterization of dispersion of DNA microarray data.

Results

Here we examine the expression data obtained from 682 Affymetrix GeneChips^® with 22 different types and we demonstrate that the Gaussian (normal) frequency distribution is characteristic for the variability of gene expression values. However, typically 5 to 15% of the samples deviate from normality. Furthermore, it is shown that the frequency distributions of the difference of expression in subsets of ordered, consecutive pairs of genes (consecutive samples) in pair-wise comparisons of replicate experiments are also normal. We describe a consecutive sampling method, which is employed to calculate the characteristic function approximating standard deviation and show that the standard deviation derived from the consecutive samples is equivalent to the standard deviation obtained from individual genes. Finally, we determine the boundaries of probability intervals and demonstrate that the coefficients defining the intervals are independent of sample characteristics, variability of data, laboratory conditions and type of chips. These coefficients are very closely correlated with Student's t-distribution.

Conclusion

In this study we ascertained that the non-systematic variations possess Gaussian distribution, determined the probability intervals and demonstrated that the K_α coefficients defining these intervals are invariant; these coefficients offer a convenient universal measure of dispersion of data. The fact that the K_α distributions are so close to t-distribution and independent of conditions and type of arrays suggests that the quantitative data provided by Affymetrix technology give "true" representation of physical processes, involved in measurement of RNA abundance.

Reviewers

This article was reviewed by Yoav Gilad (nominated by Doron Lancet), Sach Mukherjee (nominated by Sandrine Dudoit) and Amir Niknejad and Shmuel Friedland (nominated by Neil Smalheiser).

Myoepithelial carcinoma arising in an adenomyoepithelioma of the breast: Case report with immunohistochemical and mutational analysis

Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by biphasic proliferation of both epithelial and myoepithelial cells. In rare instances, the epithelial, the myoepithelial or both components of an AME may become malignant. Described herein is the case of a 69-year-old woman who presented with myoepithelial carcinoma of the breast in an AME. Malignancy of myoepithelial component (MEC) was evidenced by the presence of cytological atypia, high mitotic rate, necrosis and local invasion. Immunohistochemical study demonstrated strong expression of P53 and phosphorylated extracellular signal-regulated kinase 1/2 in MEC. Laser capture microdissection technique and mutational analysis further revealed point mutation of the p53 gene (T-->G transversion at codon 270) in this population, but not in glandular epithelial cells or adjacent normal ductal epithelium. No mutations in exons 1 and 2 of the K-, H-, and N-ras genes were identified in any of the neoplastic component. To the authors' knowledge this is the first report of a mutation in the p53 gene in a malignant AME of the breast.