Transient loss of Polycomb components induces an epigenetic cancer fate.

Although cancer initiation and progression are generally associated with the accumulation of somatic mutations1,2, substantial epigenomic alterations underlie many aspects of tumorigenesis and cancer susceptibility3-6, suggesting that genetic mechanisms might not be the only drivers of malignant transformation7. However, whether purely non-genetic mechanisms are sufficient to initiate tumorigenesis irrespective of mutations has been unknown. Here, we show that a transient perturbation of transcriptional silencing mediated by Polycomb group proteins is sufficient to induce an irreversible switch to a cancer cell fate in Drosophila. This is linked to the irreversible derepression of genes that can drive tumorigenesis, including members of the JAK-STAT signalling pathway and zfh1, the fly homologue of the ZEB1 oncogene, whose aberrant activation is required for Polycomb perturbation-induced tumorigenesis. These data show that a reversible depletion of Polycomb proteins can induce cancer in the absence of driver mutations, suggesting that tumours can emerge through epigenetic dysregulation leading to inheritance of altered cell fates.

Sentinel lymph node biopsy following previous axillary surgery in recurrent breast cancer.

INTRODUCTION: Ipsilateral breast recurrence or second primary breast cancer can develop in patients who have undergone breast conserving surgery (BCS) and axillary surgery. The purpose of this study was to examine the feasibility of a reoperative sentinel lymph node biopsy (SLNB) as a repeated axillary staging procedure. PATIENTS AND METHODS: From August 2014 through January 2017 patients with locally recurrent breast cancer or with BRCA mutation requiring risk reduction mastectomy as a second surgical procedure, underwent repeat SLNB in three Hungarian Breast Units with a radiocolloid (and blue dye) technique. RESULTS: Hundred and sixty repeat SLNBs were analysed, 80 after previous SLNB and 80 after previous total or partial axillary lymph node dissection (ALND). SLN identification was successful in 106 patients (66%); 77/80 (77.5%) and 44/80 (55%) in the SLNB and ALND groups, respectively. (p < 0.003). Extra-axillary lymph drainage was more frequent in the ALND group (19/44, 43,2% versus 7/62, 11,3%; p < 0.001). Lymphatic drainage to the contralateral axilla was observed in 14 patients (11 in the ALND group, p = 0.025), isolated parasternal drainage was detected in 4 patients (p = 0.31). Only 9/106 patients with successful repeat SLNB (8,8%, all with 1 SLN removed) had SLN metastases CONCLUSIONS: Repeat SLNB is feasible in patients with ipsilateral breast tumor recurrence or new ipsilateral primary tumor after previous BCS and axillary staging. Repeat SLNB should replace routine ALND as the standard axillary restaging procedure in recurrent disease with a clinically negative axilla. Preoperative lymphoscintigraphy is important to explore extra-axillary lymphatic drainage in this restaging setting.

Correction: Musashi RNA-binding protein 2 regulates estrogen receptor 1 function in breast cancer.

The original version of this article contained error in Figure 2e. In Figure 2e, the 6th colony image of T47D cells treated with shMSI2 was inadvertently replaced with a duplicate of 7th colony image. However, the conclusions reported in the manuscript are not affected by figure replacement. The authors regret that these errors were made and apologize for the confusion and inconvenience. The correct version of this figure panel appears in the Author Correction associated with this Article.

Activation of tumor suppressor LKB1 by honokiol abrogates cancer stem-like phenotype in breast cancer via inhibition of oncogenic Stat3.

Tumor suppressor and upstream master kinase Liver kinase B1 (LKB1) plays a significant role in suppressing cancer growth and metastatic progression. We show that low-LKB1 expression significantly correlates with poor survival outcome in breast cancer. In line with this observation, loss-of-LKB1 rendered breast cancer cells highly migratory and invasive, attaining cancer stem cell-like phenotype. Accordingly, LKB1-null breast cancer cells exhibited an increased ability to form mammospheres and elevated expression of pluripotency-factors (Oct4, Nanog and Sox2), properties also observed in spontaneous tumors in Lkb1-/- mice. Conversely, LKB1-overexpression in LKB1-null cells abrogated invasion, migration and mammosphere-formation. Honokiol (HNK), a bioactive molecule from Magnolia grandiflora increased LKB1 expression, inhibited individual cell-motility and abrogated the stem-like phenotype of breast cancer cells by reducing the formation of mammosphere, expression of pluripotency-factors and aldehyde dehydrogenase activity. LKB1, and its substrate, AMP-dependent protein kinase (AMPK) are important for HNK-mediated inhibition of pluripotency factors since LKB1-silencing and AMPK-inhibition abrogated, while LKB1-overexpression and AMPK-activation potentiated HNK's effects. Mechanistic studies showed that HNK inhibited Stat3-phosphorylation/activation in an LKB1-dependent manner, preventing its recruitment to canonical binding-sites in the promoters of Nanog, Oct4 and Sox2. Thus, inhibition of the coactivation-function of Stat3 resulted in suppression of expression of pluripotency factors. Further, we showed that HNK inhibited breast tumorigenesis in mice in an LKB1-dependent manner. Molecular analyses of HNK-treated xenografts corroborated our in vitro mechanistic findings. Collectively, these results present the first in vitro and in vivo evidence to support crosstalk between LKB1, Stat3 and pluripotency factors in breast cancer and effective anticancer modulation of this axis with HNK treatment.

Eight-year follow up result of the OTOASOR trial: The Optimal Treatment Of the Axilla - Surgery Or Radiotherapy after positive sentinel lymph node biopsy in early-stage breast cancer: A randomized, single centre, phase III, non-inferiority trial.

INTRODUCTION: The National Institute of Oncology, Budapest conducted a single centre randomized clinical study. The OTOASOR (Optimal Treatment Of the Axilla - Surgery Or Radiotherapy) trial compares completion of axillary lymph node dissection (cALND) to regional nodal irradiation (RNI) in patients with sentinel lymph node metastasis (pN1sn) in stage I-II breast cancer. PATIENTS AND METHODS: Patients with primary invasive breast cancer (cN0 and cT ≤ 3 cm) were randomized before surgery for cALND (standard treatment) or RNI (investigational treatment). Sentinel lymph nodes (SN) were investigated with serial sectioning at 0.5 mm levels by hematoxylin-eosin staining. Investigational treatment arm patients received 50 Gy RNI instead of cALND. Adjuvant treatment and follow up were performed according to the actual guidelines. Between August 2002 and June 2009, 1054 patients were randomized for cALND and 1052 patients for RNI. SN was evaluated in 2073 patients and was positive in 526 patients (25.4%). 474 cases were evaluable (244 in the cALND and 230 in the RNI arm), and in the cALND group 94 of 244 patients (38.5%) who underwent completion axillary surgery has additional positive nodes. The two arms were well balanced according to the majority of main prognostic factors. Primary endpoint was axillary recurrence and secondary endpoints were overall survival (OS) and disease-free survival (DFS). RESULTS: Mean follow-up was 97 months (Q1-Q3: 80-120). Axillary recurrence was 2.0% in cALND arm vs. 1.7% in RNI arm (p = 1.00). OS at 8 years was 77.9% vs. 84.8% (p = 0.060), and DFS was 72.1% in cALND arm and 77.4% after RNI (p = 0.51). The results show that RNI is statistically not inferior to cALND treatment. CONCLUSIONS: The long term follow-up results of this prospective-randomized trial suggest that RNI without cALND does not increase the risk of axillary failure in selected patients with early-stage invasive breast cancer (cT ≤ 3 cm, cN0) and pN1(sn). Axillary radiotherapy should be an alternative treatment for selected patients with sentinel lymph node metastases.

Musashi RNA-binding protein 2 regulates estrogen receptor 1 function in breast cancer.

Musashi RNA-binding protein 2 (MSI2) has important roles in human cancer. However, the regulatory mechanisms by which MSI2 alters breast cancer pathophysiology have not been clearly identified. Here we demonstrate that MSI2 directly regulates estrogen receptor 1 (ESR1), which is a well-known therapeutic target and has been shown to reflect clinical outcomes in breast cancer. Based on gene expression data analysis, we found that MSI2 expression was highly enriched in estrogen receptor (ER)-positive breast cancer and that MSI2 expression was significantly correlated with ESR1 expression, including expression of ESR1 downstream target genes. In addition, MSI2 levels were associated with clinical outcomes. MSI2 influenced breast cancer cell growth by altering ESR1 function. MSI2 alters ESR1 by binding specific sites in ESR1 RNA and by increasing ESR1 protein stability. Taken together, our findings identified a novel regulatory mechanism of MSI2 as an upstream regulator of ESR1 and revealed the clinical relevance of the RNA-binding protein MSI2 in breast cancer.

Arginyltransferase suppresses cell tumorigenic potential and inversely correlates with metastases in human cancers.

Arginylation is an emerging post-translational modification mediated by arginyltransferase (ATE1) that is essential for mammalian embryogenesis and regulation of the cytoskeleton. Here, we discovered that Ate1-knockout (KO) embryonic fibroblasts exhibit tumorigenic properties, including abnormally rapid contact-independent growth, reduced ability to form cell-cell contacts and chromosomal aberrations. Ate1-KO fibroblasts can form large colonies in Matrigel and exhibit invasive behavior, unlike wild-type fibroblasts. Furthermore, Ate1-KO cells form tumors in subcutaneous xenograft assays in immunocompromised mice. Abnormal growth in these cells can be partially rescued by reintroduction of stably expressed specific Ate1 isoforms, which also reduce the ability of these cells to form tumors. Tumor array studies and bioinformatics analysis show that Ate1 is downregulated in several types of human cancer samples at the protein level, and that its transcription level inversely correlates with metastatic progression and patient survival. We conclude that Ate1-KO results in carcinogenic transformation of cultured fibroblasts, suggesting that in addition to its previously known activities Ate1 gene is essential for tumor suppression and also likely participates in suppression of metastatic growth.

Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors.

High-grade serous ovarian carcinoma (HGSOC) and basal-like breast cancer (BLBC) share many features including TP53 mutations, genomic instability and poor prognosis. We recently reported that Elafin is overexpressed by HGSOC and is associated with poor overall survival. Here, we confirm that Elafin overexpression is associated with shorter survival in 1000 HGSOC patients. Elafin confers a proliferative advantage to tumor cells through the activation of the MAP kinase pathway. This mitogenic effect can be neutralized by RNA interference, specific antibodies and a MEK inhibitor. Elafin expression in patient-derived samples was also associated with chemoresistance and strongly correlates with bcl-xL expression. We extended these findings into the examination of 1100 primary breast tumors and six breast cancer cell lines. We observed that Elafin is overexpressed and secreted specifically by BLBC tumors and cell lines, leading to a similar mitogenic effect through activation of the MAP kinase pathway. Here too, Elafin overexpression is associated with poor overall survival, suggesting that it may serve as a biomarker and therapeutic target in this setting.

The EMT activator ZEB1 promotes tumor growth and determines differential response to chemotherapy in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a B-cell malignancy characterized by a poor response to treatment and prognosis. Constitutive activation of different signaling pathways in subsets of MCLs, through genetic and/or nongenetic alterations, endows tumor cells with enhanced proliferation and reduced apoptosis. The canonical Wnt pathway (ß-catenin/TCF-LEF), implicated in the pathogenesis of numerous cancers, is constitutively active in half of MCLs. Here, we show that ZEB1, a transcription factor better known for promoting metastasis in carcinomas, is expressed in primary MCLs with active Wnt signaling. ZEB1 expression in MCL cells depends on Wnt, being downregulated by ß-catenin knockdown or blocking of Wnt signaling by salinomycin. Knockdown of ZEB1 reduces in vitro cell viability and proliferation in MCL cells, and, importantly, tumor growth in mouse xenograft models. ZEB1 activates proliferation-associated (HMGB2, UHRF1, CENPF, MYC, MKI67, and CCND1) and anti-apoptotic (MCL1, BCL2, and BIRC5) genes and inhibits pro-apoptotic ones (TP53, BBC3, PMAIP1, and BAX). We show that ZEB1 expression in MCL cells determines differential resistance to chemotherapy drugs and regulates transporters involved in drug influx/efflux. Downregulation of ZEB1 by salinomycin increases the sensitivity of MCL cells to the cytotoxic effect of doxorubicin, cytarabine and gemcitabine. Lastly, salinomycin and doxorubicin display a synergistic effect in established and primary MCL cells. These results identify ZEB1 in MCL where it promotes cell proliferation, enhanced tumor growth and a differential response to chemotherapy drugs. ZEB1 could thus potentially become a predictive biomarker and therapeutic target in this lymphoma.

Selection of optimal combinations of target genes for therapeutic multi-gene silencing based on miRNA co-regulation.

Therapeutic gene silencing is a promising approach for treatment of cancer. Despite substantial efforts, however, only few such therapeutic methods have been clinically tested. The heterogeneity in gene expression profiles among malignant tissues and the dynamic control of gene expression in individual tumors makes identifying universal and effective targets a challenge. Further development of gene silencing therapy requires new approaches to comprehend and manage gene expression in cancer cells. In this study, we proposed and evaluated experimentally a new approach to design multi-gene silencing therapy. Using a simplified model of gene expression control, we show that genes commonly regulated by the same microRNA represent optimal combinations of targets for small hairpin RNA/small interfering RNA-based gene silencing. The proposed method of target gene selection and co-silencing can be explored as an algorithm for personalized cancer gene therapy.

First-principle calculations of the Berry curvature of Bloch states for charge and spin transport of electrons.

Recent progress in wave packet dynamics based on the insight of Berry pertaining to adiabatic evolution of quantum systems has led to the need for a new property of a Bloch state, the Berry curvature, to be calculated from first principles. We report here on the response to this challenge by the ab initio community during the past decade. First we give a tutorial introduction of the conceptual developments we mentioned above. Then we describe four methodologies which have been developed for first-principle calculations of the Berry curvature. Finally, to illustrate the significance of the new developments, we report some results of calculations of interesting physical properties such as the anomalous and spin Hall conductivity as well as the anomalous Nernst conductivity and discuss the influence of the Berry curvature on the de Haas-van Alphen oscillation.

A comprehensive overview of targeted therapy in metastatic renal cell carcinoma.

Chemotherapy and immunotherapy failed to deliver decisive results in the systemic treatment of metastatic renal cell carcinoma. Agents representing the current standards operate on members of the RAS signal transduction pathway. Sunitinib (targeting vascular endothelial growth factor), temsirolimus (an inhibitor of the mammalian target of rapamycin - mTOR) and pazopanib (a multi-targeted receptor tyrosine kinase inhibitor) are used in the first line of recurrent disease. A combination of bevacizumab (inhibition of angiogenesis) plus interferon α is also first-line therapy. Second line options include everolimus (another mTOR inhibitor) as well as tyrosine kinase inhibitors for patients who previously received cytokine. We review the results of clinical investigations focusing on survival benefit for these agents. Additionally, trials focusing on new agents, including the kinase inhibitors axitinib, tivozanib, dovitinib and cediranib and monoclonal antibodies including velociximab are also discussed. In addition to published outcomes we also include follow-up and interim results of ongoing clinical trials. In summary, we give a comprehensive overview of current advances in the systemic treatment of metastatic renal cell carcinoma.

Intrinsic optical dichroism in the chiral superconducting state of Sr2RuO4.

We present an analysis of the Hall conductivity σ(xy)(ω,T) in time reversal symmetry breaking states of exotic superconductors. We find that the dichroic signal is nonzero in systems with interband order parameters. This new intrinsic mechanism may explain the Kerr effect observed in strontium ruthenate and possibly other superconductors. We predict coherence factor effects in the temperature dependence of the imaginary part of the ac Hall conductivity Imσ(xy)(ω,T), which can be tested experimentally.

PSMB7 is associated with anthracycline resistance and is a prognostic biomarker in breast cancer.

BACKGROUND: To date individual markers have failed to correctly predict resistance against anticancer agents in breast cancer. We used gene expression patterns attributable to chemotherapy-resistant cells to detect potential new biomarkers related to anthracycline resistance. One of the genes, PSMB7, was selected for further functional studies and clinical validation. METHODS: We contrasted the expression profiles of four pairs of different human tumour cell lines and of their counterparts resistant to doxorubicin. Observed overexpression of PSMB7 in resistant cell lines was validated by immunohistochemistry. To examine its function in chemoresistance, we silenced the gene by RNA interference (RNAi) in doxorubicin-resistant MCF-7 breast cancer cells, then cell vitality was measured after doxorubicin treatment. Microarray gene expression from GEO raw microarray samples with available progression-free survival data was downloaded, and expression of PSMB7 was used for grouping samples. RESULTS: After doxorubicin treatment, 79.8+/-13.3% of resistant cells survived. Silencing of PSMB7 in resistant cells decreased survival to 31.8+/-6.4% (P>0.001). A similar effect was observed after paclitaxel treatment. In 1592 microarray samples, the patients with high PSMB7 expression had a significantly shorter survival than the patients with low expression (P<0.001). CONCLUSION: Our findings suggest that high PSMB7 expression is an unfavourable prognostic marker in breast cancer.

A snapshot of microarray-generated gene expression signatures associated with ovarian carcinoma.

It was hypothesized that analysis of global gene expression in ovarian carcinoma can identify dysregulated genes that can serve as molecular markers and provide further insight into carcinogenesis and provide the basis for development of new diagnostic tools as well as new targeted therapy protocols. By applying bioinformatics tools for screening of biomedical databases, a gene expression profile databank, specific for ovarian carcinoma, was constructed with utilizable data sets published in 28 studies that applied different array technology platforms. The data sets were divided into four compartments: (i) genes associated with carcinogenesis: in 14 studies, 1881 genes were extracted, 75 genes were identified in more than one study, and only 4 genes (PRKCBP1, SPON1, TACSTD1, and PTPRM) were identified in three studies. (ii) Genes associated with histologic subtypes: in four studies, 463 genes could be identified, but none of them was identified in more than a single study. (iii) Genes associated with therapy response: in seven studies, 606 genes were identified from which 38 were differentially regulated in at least two studies, 3 genes (TMSB4X, GRN, and TJP1) in three studies, and 1 gene (IFITM1) in four studies. (iv) Genes associated with prognosis and progression: 254 genes were found in seven studies. From these genes, merely three were identified in at least two different studies. This snapshot of available gene expression data not only provides independently described potential diagnostic and therapeutic targets for ovarian carcinoma but also emphasizes the drawbacks of the current state of global gene expression analyses in ovarian cancer.

Multivariate analysis of oestrogen receptor alpha, pS2, metallothionein and CD24 expression in invasive breast cancers.

Determination of oestrogen receptor alpha (ER) represents at present the most important predictive factor in breast cancers. Data of ours and of other authors suggest that promising predictive/prognostic factors may also include pS2, metallothionein (MT) and CD24. Present study aimed at determining prognostic and predictive value of immunohistochemical determination of ER, pS2, MT, and CD24 expression in sections originating from 104 patients with breast cancer. An univariate and multivariate analysis was performed. Both univariate and multivariate analyses demonstrated that cytoplasmic-membranous expression of CD24 (CD24c-m) represents a strong unfavourable prognostic factor in the entire group and in most of the subgroups of patients. In several subgroups of the patients also a prognostic value was demonstrated of elevated expression of pS2 and of membranous expression of CD24. Our studies demonstrated that all patients with good prognostic factors (higher ER and pS2 expressions, lower MT expression, CD24c-m negativity) survived total period of observation (103 months). The study documented that cytoplasmic-membranous expression of CD24 represented an extremely strong unfavourable prognostic factor in breast cancer. Examination of the entire panel of the studied proteins permitted to select a group of patients of an exceptionally good prognosis.

Effect of spin-orbit interaction on a magnetic impurity in the vicinity of a surface.

We propose a new mechanism for surface-induced magnetic anisotropy to explain the thickness dependence of the Kondo resistivity of thin films of dilute magnetic alloys. The surface anisotropy energy, generated by spin-orbit coupling on the magnetic impurity itself, is an oscillating function of the distance d from the surface and decays as 1/d2. Numerical estimates based on simple models suggest that this mechanism, unlike its alternatives, gives rise to an effect of the desired order of magnitude.

Three mechanisms in the pathogenesis of pre-eclampsia suggested by over-represented transcription factor-binding sites detected with comparative promoter analysis.

Microarray studies generating lists of genes with altered expression in placentas from pregnancies complicated with pre-eclampsia (PE) have so far been published in several different studies. Working under the assumption that altered gene expression in PE may be the result of altered expression of regulatory transcription factors (TFs), we looked for over-represented TF-binding sites (TFBSs)-which indicate the involvement of TFs in gene regulatory networks-in lists of genes (n = 143) compiled in these studies. We compared the prevalence of TFBSs in the promoter regions of 68 genes with the background prevalence of TFBSs in promoters of the human genome. The prevalence of the E47, sterol regulatory element binding protein (SREBP) and NFKB-p50 TFBSs was higher (P < 0.005) in the promoter sequences of the PE gene lists than in the background model. Each of these TFBSs could be implicated in the development of PE. The E47 protein is an E-protein or basic helix-loop-helix (bHLH) TF. Data support the role of bHLHs in the differentiation of placental tissue. SREBP-1, a lipid-sensing sterol regulatory element-binding protein, is a critical regulator of fatty acid homeostasis in the placenta. The target genes of NFKB-p50 determine inflammatory response, and aberrant cytokine homeostasis is a further sign of PE. These TFs may provide an insight into the pathogenesis of the disease.

The PI3K inhibitor LY294002 blocks drug export from resistant colon carcinoma cells overexpressing MRP1.

Multidrug resistance may be achieved by the activation of membrane transporters, detoxification, alterations in DNA repair or failure in apoptotic pathways. Recent data have suggested an involvement of mitogenic signalling pathways mediated by Ras and phosphoinositol-3-kinase (PI3K/Akt) in controlling multidrug resistance. Since these pathways are important targets for therapeutic interference, we sought to investigate whether blocking effectors kinases by specific inhibitors would result in a sensitization toward cytotoxic drugs. We found that cotreatment of drug-resistant HT29RDB colon cancer cells with the topoisomerase inhibitor doxorubicin and the PI3K-inhibitor LY294002 resulted in massive apoptosis, while cotreatment with the Mek inhibitors PD98059 or U0126 had no effect. This suggested that the PI3K-pathways controls cell survival and drug resistance in these cells. Besides blocking Akt phosphorylation, the PI3K-inibitor increased the intracellular doxorubicin concentration threefold. LY294002 inhibits drug export in a competitive manner as revealed by measuring drug efflux in the presence and the absence of inhibitor. The efficacy of drug efflux inhibition by LY294002 was similar to that achieved by the MRP1 inhibitors MK571 and genistein. We conclude that the PI3K inhibitor LY294002 may have therapeutic potential when combined with doxorubicin in the treatment of MRP1-mediated drug resistance.

Elevated metallothionein (MT) expression in invasive ductal breast cancers predicts tamoxifen resistance.

Elevated expression of the low molecular weight metallothionein (MT) proteins can be found typically in breast cancer cases with less favourable prognosis. The MT gene has been described to be potentially down-regulated by estrogen receptor alpha. The present study is aimed at examining the predictive value of MT expression for results of tamoxifen treatment in breast cancer in relation to steroid receptor status. Sixty patients with primary invasive ductal breast cancers with post-operative tamoxifen treatment were enrolled in the study. In paraffin sections of the studied tumours immmunohistochemical reactions were performed using antibodies directed against MT, estrogen receptors (ER) and progesterone receptors (PgR). Results of the immunohistochemical reactions and of clinical observations were analysed using multivariate progression analysis based on the Cox proportional hazard model. Elevated MT expression was demonstrated to be typical for cases with documented relapse of the disease (P<0.001) or terminated by death (P=0.03). Decreased ER expression was found to be typical for cases of a higher grade (P=0.02) and cases terminated by death (P=0.006). The multivariate analysis showed that elevated MT expression was characteristic for cases with shorter overall survival time (P=0.04). The data showed that MT carried an independent, and also independent from ER status, unfavourable predictive value as far as results of tamoxifen treatment were concerned.