BRCA1 5083del19 mutant allele selectively up-regulates periostin expression in vitro and in vivo

FTH1P3, a Novel H-Ferritin Pseudogene Transcriptionally Active, Is Ubiquitously Expressed and Regulated during Cell Differentiation

Ferritin, the major iron storage protein, performs its essential functions in the cytoplasm, nucleus and mitochondria. The variable assembly of 24 subunits of the Heavy (H) and Light (L) type composes the cytoplasmic molecule. In humans, two distinct genes code these subunits, both belonging to complex multigene families. Until now, one H gene has been identified with the coding sequence interrupted by three introns and more than 20 intronless copies widely dispersed on different chromosomes. Two of the intronless genes are actively transcribed in a tissue-specific manner. Herein, we report that FTH1P3, another intronless pseudogene, is transcribed. FTH1P3 transcript was detected in several cell lines and tissues, suggesting that its transcription is ubiquitary, as it happens for the parental ferritin H gene. Moreover, FTH1P3 expression is positively regulated during the cell differentiation process.

DJ-1 in endometrial cancer: a possible biomarker to improve differential diagnosis between subtypes

OBJECTIVE

The objectives of this study were to characterize the well-defined endometrial cancer (EC) type I (endometrioid [EEC] G1-G2) versus the prototype of EC type II (serous [ESC]) and to evaluate the expression of specific biomarkers differentially expressed between 2 well-defined types, in those EC subtypes (such as EEC G3) disputed between types I and II.

METHODS

Data from 25 patients (10 EEC G1-G2, 8 EEC G3, 5 ESC, and 2 clear cell) submitted to the surgical treatment were collected. Two-dimensional electrophoresis and mass spectrometry (MS) analysis were performed on 5 EEC G1-G2 and 5 healthy endometrial samples of the same patients. Differentially expressed proteins, such as DJ-1, were validated by Western blot. In patients with EEC G1-G2, serum levels of DJ-1, an overexpressed oncoprotein related to EC pathogenesis and progression, were evaluated and then compared with levels identified in patients with ESC and healthy controls. The DJ-1 immunohistochemical (IHC) staining was performed on neoplastic and healthy endometrium collected from the same patients. The 8 stored samples of EEC G3 were submitted to DJ-1 IHC assays.

RESULTS

The 2-dimensional electrophoresis analysis identified 1040 protein spots differentially expressed in EEC G1-G2 compared with healthy endometrium. Forty-two spots were subjected to liquid chromatography-MS/MS analysis. Thirty-three up-regulated (like an annexin 2 [ANXA2] shorter isoform, CAPG [macrophage-capping protein], DJ-1/PARK7) and 9 down-regulated (like calreticulin and ubiquitin carboxyl-terminal hydrolase isozyme L1) proteins were identified and validated by Western blot. A significant increase in serum DJ-1 levels of EEC G1-G2 versus the healthy controls and in ESC versus EEC patients was observed. DJ-1 IHC score was significantly higher in ESC versus those EEC G1-G2. In 3 cases of EEC G3, the DJ-1 expression was similar to the ESC subtype.

CONCLUSIONS

The identification of proteins, such as DJ-1, differentially expressed, between well-defined EC types I and II allows to make a subtype-specific presurgical diagnosis and help surgeon to safely preoperatively choose a proper surgical treatment.

Periostin and receptor activator of nuclear factor κ-B ligand expression in allergic fungal rhinosinusitis

BACKGROUND

Allergic fungal rhinosinusitis (AFRS) is a disease demonstrating substantial eosinophilic inflammation and characteristic radiographic bony erosion/expansion. Periostin is an extracellular matrix protein associated with eosinophil accumulation in eosinophilic esophagitis, allergic asthma mucus production, and chronic rhinosinusitis (CRS) polyp formation. Receptor activator of nuclear factor κ-B ligand (RANKL) is an osteoclast activator present in osteoporosis and periodontal disease. We sought to evaluate periostin and RANKL expression in AFRS and correlate these levels with radiographic scales of disease severity.

METHODS

Thirty sinus tissue specimens were intraoperatively collected from 3 patient groups: AFRS; CRS without nasal polyps (CRSsNP); and controls (n = 10 per group). Specimens were analyzed by semiquantitative reverse-transcription polymerase chain reaction (sq-RT-PCR) and immunofluorescence (IF) labeling/confocal microscopy for the presence of both periostin and RANKL. Immunofluorescence staining intensity was quantified by pixel density analysis. Preoperative computed tomography (CT) scans from each patient were scored using both the Lund-Mackay and CT bone erosion scoring systems.

RESULTS

Periostin was significantly elevated in AFRS sinus tissue compared to CRSsNP and controls, as demonstrated by IF (p < 0.001) and PCR (p = 0.011). RANKL was not detected in sinus tissue by IF or PCR. Periostin levels positively correlated with radiographic indices of disease severity for both soft tissue and bone, using Lund-Mackay (r = 0.926 [PCR] and r = 0.581 [IF]) and CT bone erosion (r = 0.672 [PCR] and r = 0.616 [IF]) scoring systems, respectively.

CONCLUSION

Periostin is increased in AFRS tissue compared to CRSsNP and controls. Periostin levels positively correlate with radiologic disease severity scores. The increased levels of periostin in AFRS are possibly tied to its intense eosinophilic inflammatory etiology.

Clinical interpretation and implications of whole-genome sequencing

IMPORTANCE

Whole-genome sequencing (WGS) is increasingly applied in clinical medicine and is expected to uncover clinically significant findings regardless of sequencing indication.

OBJECTIVES

To examine coverage and concordance of clinically relevant genetic variation provided by WGS technologies; to quantitate inherited disease risk and pharmacogenomic findings in WGS data and resources required for their discovery and interpretation; and to evaluate clinical action prompted by WGS findings.

DESIGN, SETTING, AND PARTICIPANTS

An exploratory study of 12 adult participants recruited at Stanford University Medical Center who underwent WGS between November 2011 and March 2012. A multidisciplinary team reviewed all potentially reportable genetic findings. Five physicians proposed initial clinical follow-up based on the genetic findings.

MAIN OUTCOMES AND MEASURES

Genome coverage and sequencing platform concordance in different categories of genetic disease risk, person-hours spent curating candidate disease-risk variants, interpretation agreement between trained curators and disease genetics databases, burden of inherited disease risk and pharmacogenomic findings, and burden and interrater agreement of proposed clinical follow-up.

RESULTS

Depending on sequencing platform, 10% to 19% of inherited disease genes were not covered to accepted standards for single nucleotide variant discovery. Genotype concordance was high for previously described single nucleotide genetic variants (99%-100%) but low for small insertion/deletion variants (53%-59%). Curation of 90 to 127 genetic variants in each participant required a median of 54 minutes (range, 5-223 minutes) per genetic variant, resulted in moderate classification agreement between professionals (Gross κ, 0.52; 95% CI, 0.40-0.64), and reclassified 69% of genetic variants cataloged as disease causing in mutation databases to variants of uncertain or lesser significance. Two to 6 personal disease-risk findings were discovered in each participant, including 1 frameshift deletion in the BRCA1 gene implicated in hereditary breast and ovarian cancer. Physician review of sequencing findings prompted consideration of a median of 1 to 3 initial diagnostic tests and referrals per participant, with fair interrater agreement about the suitability of WGS findings for clinical follow-up (Fleiss κ, 0.24; P < 001).

CONCLUSIONS AND RELEVANCE

In this exploratory study of 12 volunteer adults, the use of WGS was associated with incomplete coverage of inherited disease genes, low reproducibility of detection of genetic variation with the highest potential clinical effects, and uncertainty about clinically reportable findings. In certain cases, WGS will identify clinically actionable genetic variants warranting early medical intervention. These issues should be considered when determining the role of WGS in clinical medicine.

Identification of H ferritin-dependent and independent genes in K562 differentiating cells by targeted gene silencing and expression profiling

Ferritin is best known as the key molecule in intracellular iron storage, and is involved in several metabolic processes such as cell proliferation, differentiation and neoplastic transformation. We have recently demonstrated that the shRNA silencing of the ferritin heavy subunit (FHC) in a melanoma cell line is accompanied by a consistent modification of gene expression pattern leading to a reduced potential in terms of proliferation, invasiveness, and adhesion ability of the silenced cells. In this study we sought to define the repertoire of genes whose expression might be affected by FHC during the hemin-induced differentiation of the erythromyeloid cell line K562. To this aim, gene expression profiling was performed in four different sets of cells: i) wild type K562; ii) sh-RNA FHC-silenced K562; iii) hemin-treated wild-type K562; and iv) hemin-treated FHC-silenced K562. Statistical analysis of the gene expression data, performed by two-factor ANOVA, identified three distinct classes of transcripts: a) Class 1, including 657 mRNAs whose expression is modified exclusively during hemin-induced differentiation of K562 cells, independently from the FHC relative amounts; b) Class 2, containing a set of 70 mRNAs which are consistently modified by hemin and FHC-silencing; and c) Class 3, including 128 transcripts modified by FHC-silencing but not by hemin. Our data indicate that FHC may function as a modulator of gene expression during erythroid differentiation and add new findings to the knowledge of the complex gene network modulated during erythroid differentiation.

Polymorphic repeat length in the AIB1 gene and breast cancer risk in BRCA1 and BRCA2 mutation carriers: a meta-analysis of observational studies

OBJECTIVES

We carried out a meta-analysis focusing on the relationship between length of AIB1 gene poly-Q repeat domain as a modifier of breast cancer (BC) susceptibility in patients with BRCA1 and BRCA2 mutation carriers.

DATA SOURCES

We searched MEDLINE and EMBASE for all medical literature published until February, 2012.

STUDY ELIGIBILITY CRITERIA

Studies were included in the meta-analysis if they met all the predetermined criteria, such as: (a) case-control or cohort studies; (b) the primary outcome was clearly defined as BC; (c) the exposure of interest measured was AIB1 polyglutamine repeat length genotype; (d) provided relative risk (RR) or odds ratio (OR) estimates and their 95% confidence intervals (CIs). SYNTHESIS METHODS: Two of the authors independently evaluated the quality of the studies included and extracted the data. Meta-analyses were performed for case-control and cohort studies separately. Heterogeneity was examined and the publication bias was assessed with a funnel plot for asymmetry.

RESULT

7 studies met our predetermined inclusion criteria and were included in the meta-analysis. Overall quality ratings of the studies varied from 0.36 to 0.77, with a median of 0.5. The overall RR estimates of 29/29 poly-Q repeats on risk of BC in BRCA1/2, BRCA1, and BRCA2, were always greater than 1.00; however, this effect was not statistically significant. In the meta-analysis of studies reporting the effect of 28/28 poly-Q repeats on risk of BC in BRCA1/2, BRCA1, and BRCA2, the overall RR decreased below 1.00; however, this effect was not statistically significant. Similar estimates were shown for at least 1 allele of ≤26 repeats.

CONCLUSIONS

Genotypes of AIB1 polyglutamine polymorphism analyzed do not appear to be associated to a modified risk of BC development in BRCA1 and BRCA2 mutation carriers. Future research on length of poly-Q repeat domain and BC susceptibility should be discouraged and more promising potential sources of penetrance variation among BRCA1 and BRCA2 mutation carriers should be investigated.

BRCA1 is required for hMLH1 stabilization following doxorubicin-induced DNA damage

Human DNA mismatch repair (MMR) is involved in the removal of DNA base mismatches that arise either during DNA replication or are caused by DNA damage. In this study, we show that the activation of the MMR component hMLH1 in response to doxorubicin (DOX) treatment requires the presence of BRCA1 and that this phenomenon is mediated by an ATM/ATR dependent phosphorylation of the hMLH1 Ser-406 residue. BRCA1 is an oncosuppressor protein with a central role in the DNA damage response and it is a critical component of the ATM/ATR mediated checkpoint signaling. Starting from a previous finding in which we demonstrated that hMLH1 is able to bind to BRCA1, in this study we asked whether BRCA1 might be the bridge for ATM/ATR dependent phosphorylation of the hMLH1 molecular partner. We found that: (i) the negative modulation of BRCA1 expression is able to produce a remarkable reversal of hMLH1 stabilization, (ii) BRCA1 is required for post-translational modification produced by DOX treatment on hMLH1 which is, in turn, attributed to the ATM/ATR activity, (iii) the serine 406 phosphorylatable residue is critical for hMLH1 activation by ATM/ATR via BRCA1. Taken together, our data lend support to the hypothesis suggesting an important role of this oncosuppressor as a scaffold or bridging protein in DNA-damage response signaling via downstream phosphorylation of the ATM/ATR substrate hMLH1.

Negative transcriptional regulation of the human periostin gene by YingYang-1 transcription factor

Periostin (POSTN), an osteoblast-specific secreted protein known to be associated with cell adhesion activity for bone formation and development by the epithelial cell-derived tumors, leads to a significant enhancement in angiogenesis and tumorigenesis. At present, little is known about the mechanisms underlying its transcriptional control either in physiological or neoplastic conditions. In this study we demonstrate that the ability of the human POSTN promoter to drive transcription mostly depends on the activity of YingYang-1 (YY1) zinc finger transcription factor. YY1, whose regulatory role in biology includes, besides transcriptional control, also chromatin remodeling, DNA damage repair and tumorigenesis, acts as a strong negative modulator of the POSTN expression. We retain that the identification of the functional role of YY1 in the transcriptional control of the human POSTN gene adds new insights in the studies focused on gene expression in normal and transformed cells.

Quantitative proteomic profiling of matched normal and tumor breast tissues

Proteomic analysis of breast cancer tissue has proven difficult due to its inherent histological complexity. This pilot study presents preliminary evidence for the ability to differentiate adenoma and invasive carcinoma by measuring changes in proteomic profile of matched normal and disease tissues. A dual lysis buffer method was used to maximize protein extraction from each biopsy, proteins digested with trypsin, and the resulting peptides iTRAQ labeled. After combining, the peptide mixtures they were separated using preparative IEF followed by RP nanoHPLC. Following MALDI MS/MS and database searching, identified proteins were combined into a nonredundant list of 481 proteins with associated normal/tumor iTRAQ ratios for each patient. Proteins were categorized by location as blood, extracellular, and cellular, and the iTRAQ ratios were normalized to enable comparison between patients. Of those proteins significantly changed (upper or lower quartile) between matched normal and disease tissues, those from two invasive carcinoma patients had >50% in common with each other but <22% in common with an adenoma patient. In invasive carcinoma patients, several cellular and extracellular proteins that were significantly increased (Periostin, Small breast epithelial mucin) or decreased (Kinectin) have previously been associated with breast cancer, thereby supporting this approach for a larger disease-stage characterization effort.

BRCA1 16 years later: risk-associated BRCA1 mutations and their functional implications

Mutations in the tumor suppressor breast cancer susceptibility gene 1 (BRCA1), an important player in the DNA damage response, apoptosis, cell cycle regulation and transcription, confer a significantly elevated lifetime risk for breast and ovarian cancer. Although the loss of wild-type BRCA1 function is an important mechanism by which mutations confer increased cancer risk, multiple studies suggest mutant BRCA1 proteins may confer functions independent of the loss of wild-type BRCA1 through dominant negative inhibition of remaining wild-type BRCA1, or through novel interactions and pathways. These functions impact various cellular processes and have the potential to significantly influence cancer initiation and progression. In this review, we discuss the functional classifications of risk-associated BRCA1 mutations and their molecular, cellular and clinical impact for mutation carriers.

The multifaceted role of periostin in tumorigenesis

Periostin, also called osteoblast-specific factor 2 (OSF-2), is a member of the fasciclin family and a disulfide-linked cell adhesion protein that has been shown to be expressed preferentially in the periosteum and periodontal ligaments, where it acts as a critical regulator of bone and tooth formation and maintenance. Furthermore, periostin plays an important role in cardiac development. Recent clinical evidence has also revealed that periostin is involved in the development of various tumors, such as breast, lung, colon, pancreatic, and ovarian cancers. Periostin interacts with multiple cell-surface receptors, most notably integrins, and signals mainly via the PI3-K/Akt and other pathways to promote cancer cell survival, epithelial-mesenchymal transition (EMT), invasion, and metastasis. In this review, aspects related to the function of periostin in tumorigenesis are summarized.