AP-2α-Mediated Activation of E2F and EZH2 Drives Melanoma Metastasis

In melanoma metastasis, the role of the AP-2α transcription factor, which is encoded by TFAP2A, is controversial as some findings have suggested tumor suppressor activity while other studies have shown high TFAP2A expression in node-positive melanoma associated with poor prognosis. Here we demonstrate that AP-2α facilitates melanoma metastasis through transcriptional activation of genes within the E2F pathway including EZH2. A BioID screen found that AP-2α interacts with members of the nucleosome remodeling and deacetylase (NuRD) complex. Loss of AP-2α removed activating chromatin marks in the promoters of EZH2 and other E2F target genes through activation of the NuRD repression complex. In melanoma cells, treatment with tazemetostat, an FDA-approved and highly specific EZH2 inhibitor, substantially reduced anchorage-independent colony formation and demonstrated heritable antimetastatic effects, which were dependent on AP-2α. Single-cell RNA sequencing analysis of a metastatic melanoma mouse model revealed hyperexpansion of Tfap2a ^High/E2F-activated cell populations in transformed melanoma relative to progenitor melanocyte stem cells. These findings demonstrate that melanoma metastasis is driven by the AP-2α/EZH2 pathway and suggest that AP-2α expression can be used as a biomarker to predict responsiveness to EZH2 inhibitors for the treatment of advanced melanomas. SIGNIFICANCE: AP-2α drives melanoma metastasis by upregulating E2F pathway genes including EZH2 through inhibition of the NuRD repression complex, serving as a biomarker to predict responsiveness to EZH2 inhibitors.

AP-2α Regulates S-Phase and Is a Marker for Sensitivity to PI3K Inhibitor Buparlisib in Colon Cancer

Activating protein 2 alpha (AP-2α; encoded by TFAP2A) functions as a tumor suppressor and influences response to therapy in several cancer types. We aimed to characterize regulation of the transcriptome by AP-2α in colon cancer. CRISPR-Cas9 and short hairpin RNA were used to eliminate TFAP2A expression in HCT116 and a panel of colon cancer cell lines. AP-2α target genes were identified with RNA sequencing and chromatin immunoprecipitation sequencing. Effects on cell cycle were characterized in cells synchronized with aphidicolin and analyzed by FACS and Premo FUCCI. Effects on invasion and tumorigenesis were determined by invasion assay, growth of xenografts, and phosphorylated histone H3 (PHH3). Knockout of TFAP2A induced significant alterations in the transcriptome including repression of TGM2, identified as a primary gene target of AP-2α. Loss of AP-2α delayed progression through S-phase into G₂-M and decreased phosphorylation of AKT, effects that were mediated through regulation of TGM2. Buparlisib (BKM120) repressed in vitro invasiveness of HCT116 and a panel of colon cancer cell lines; however, loss of AP-2α induced resistance to buparlisib. Similarly, buparlisib repressed PHH3 and growth of tumor xenografts and increased overall survival of tumor-bearing mice, whereas, loss of AP-2α induced resistance to the effect of PI3K inhibition. Loss of AP-2α in colon cancer leads to prolonged S-phase through altered activation of AKT leading to resistance to the PI3K inhibitor, Buparlisib. The findings demonstrate an important role for AP-2α in regulating progression through the cell cycle and indicates that AP-2α is a marker for response to PI3K inhibitors. IMPLICATIONS: AP-2α regulated cell cycle through the PI3K cascade and activation of AKT mediated through TGM2. AP-2α induced sensitivity to Buparlisib/BKM120, indicating that AP-2α is a biomarker predictive of response to PI3K inhibitors.

AP-2γ Is Required for Maintenance of Multipotent Mammary Stem Cells

Mammary gland ductal morphogenesis depends on the differentiation of mammary stem cells (MaSCs) into basal and luminal lineages. The AP-2γ transcription factor, encoded by Tfap2c, has a central role in mammary gland development but its effect in mammary lineages and specifically MaSCs is largely unknown. Here, we utilized an inducible, conditional knockout of Tfap2c to elucidate the role of AP-2γ in maintenance and differentiation of MaSCs. Loss of AP-2γ in the basal epithelium profoundly altered the transcriptomes and decreased the number of cells within several clusters of mammary epithelial cells, including adult MaSCs and luminal progenitors. AP-2γ regulated the expression of genes known to be required for mammary development, including Cebpb, Nfkbia, and Rspo1. As a result, AP-2γ-deficient mice exhibited repressed mammary gland ductal outgrowth and inhibition of regenerative capacity. The findings demonstrate that AP-2γ can regulate development of mammary gland structures potentially regulating maintenance and differentiation of multipotent MaSCs.

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AP-2γ-deficient mice exhibit repressed ductal outgrowth and regenerative capacity

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Loss of AP-2γ reduced cells within mammary stem and luminal progenitor clusters

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AP-2γ target genes, including Cebpb, Nfkbia, and Rspo1, regulate mammary development

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AP-2γ potentially regulates maintenance of multipotent mammary stem cells

A TFAP2C Gene Signature Is Predictive of Outcome in HER2-Positive Breast Cancer

The AP-2γ transcription factor, encoded by the TFAP2C gene, regulates the expression of estrogen receptor-alpha (ERα) and other genes associated with hormone response in luminal breast cancer. Little is known about the role of AP-2γ in other breast cancer subtypes. A subset of HER2⁺ breast cancers with amplification of the TFAP2C gene locus becomes addicted to AP-2γ. Herein, we sought to define AP-2γ gene targets in HER2⁺ breast cancer and identify genes accounting for physiologic effects of growth and invasiveness regulated by AP-2γ. Comparing HER2⁺ cell lines that demonstrated differential response to growth and invasiveness with knockdown of TFAP2C, we identified a set of 68 differentially expressed target genes. CDH5 and CDKN1A were among the genes differentially regulated by AP-2γ and that contributed to growth and invasiveness. Pathway analysis implicated the MAPK13/p38δ and retinoic acid regulatory nodes, which were confirmed to display divergent responses in different HER2⁺ cancer lines. To confirm the clinical relevance of the genes identified, the AP-2γ gene signature was found to be highly predictive of outcome in patients with HER2⁺ breast cancer. We conclude that AP-2γ regulates a set of genes in HER2⁺ breast cancer that drive cancer growth and invasiveness. The AP-2γ gene signature predicts outcome of patients with HER2⁺ breast cancer and pathway analysis predicts that subsets of patients will respond to drugs that target the MAPK or retinoic acid pathways. IMPLICATIONS: A set of genes regulated by AP-2γ in HER2⁺ breast cancer that drive proliferation and invasion were identified and provided a gene signature that is predictive of outcome in HER2⁺ breast cancer.

Targeting the SUMO pathway as a novel treatment for anaplastic thyroid cancer

Cancer stem cells (CSCs) are expanded in anaplastic thyroid cancer (ATC) and standard treatment approaches have failed to improve survival, suggesting a need to specifically target the CSC population. Recent studies in breast and colorectal cancer demonstrated that inhibition of the SUMO pathway repressed CD44 and cleared the CSC population, mediated through SUMO-unconjugated TFAP2A. We sought to evaluate effects of inhibiting the SUMO pathway in ATC. ATC cell lines and primary ATC tumor samples were evaluated. The SUMO pathway was inhibited by knockdown of PIAS1 and use of SUMO inhibitors anacardic acid and PYR-41. The expression of TFAP2A in primary ATC was examined by immunohistochemistry. All ATC cell lines expressed TFAP2A but only 8505C expressed SUMO-conjugated TFAP2A. In 8505C only, inhibition of the SUMO pathway by knockdown of PIAS1 or treatment with SUMO inhibitors repressed expression of CD44 with a concomitant loss of SUMO-conjugated TFAP2A. The effect of SUMO inhibition on CD44 expression was dependent upon TFAP2A. Treatment with SUMO inhibitors resulted in a statistically improved tumor-free survival in mice harboring 8505C xenografts. An examination of primary ATC tissue determined that TFAP2A was expressed in 4 of 11 tumors surveyed. We conclude that inhibition of the SUMO pathway repressed the CSC population, delaying the outgrowth of tumor xenografts in ATC. The effect of SUMO inhibition was dependent upon expression of SUMO-conjugated TFAP2A, which may serve as a molecular marker for therapeutic effects of SUMO inhibitors. The findings provide pre-clinical evidence for development of SUMO inhibitors for the treatment of ATC.

Inhibiting the SUMO Pathway Represses the Cancer Stem Cell Population in Breast and Colorectal Carcinomas

Many solid cancers have an expanded CD44^+/hi/CD24^−/low cancer stem cell (CSC) population, which are relatively chemoresistant and drive recurrence and metastasis. Achieving a more durable response requires the development of therapies that specifically target CSCs. Recent evidence indicated that inhibiting the SUMO pathway repressed tumor growth and invasiveness, although the mechanism has yet to be clarified. Here, we demonstrate that inhibition of the SUMO pathway repressed MMP14 and CD44 with a concomitant reduction in cell invasiveness and functional loss of CSCs in basal breast cancer. Similar effects were demonstrated with a panel of E1 and E3 SUMO inhibitors. Identical results were obtained in a colorectal cancer cell line and primary colon cancer cells. In both breast and colon cancer, SUMO-unconjugated TFAP2A mediated the effects of SUMO inhibition. These data support the development of SUMO inhibitors as an approach to specifically target the CSC population in breast and colorectal cancer.

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Sumoylation regulates CD44 and MMP14 expression in basal breast and colon cancer

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SUMO inhibition clears cancer stem cells, repressing invasiveness and tumor growth

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Anacardic acid functions as a SUMO inhibitor to repress cancer stem cells

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TFAP2A mediates anti-tumor effects of SUMO inhibition in breast and colon cancers

EGFR Is Regulated by TFAP2C in Luminal Breast Cancer and Is a Target for Vandetanib

Expression of TFAP2C in luminal breast cancer is associated with reduced survival and hormone resistance, partially explained through regulation of RET. TFAP2C also regulates EGFR in HER2 breast cancer. We sought to elucidate the regulation and functional role of EGFR in luminal breast cancer. We used gene knockdown (KD) and treatment with a tyrosine kinase inhibitor (TKI) in cell lines and primary cancer isolates to determine the role of RET and EGFR in regulation of p-ERK and tumorigenesis. KD of TFAP2C decreased expression of EGFR in a panel of luminal breast cancers, and chromatin immunoprecipitation sequencing (ChIP-seq) confirmed that TFAP2C targets the EGFR gene. Stable KD of TFAP2C significantly decreased cell proliferation and tumor growth, mediated in part through EGFR. While KD of RET or EGFR reduced proliferation (31% and 34%, P < 0.01), combined KD reduced proliferation greater than either alone (52% reduction, P < 0.01). The effect of the TKI vandetanib on proliferation and tumor growth response of MCF-7 cells was dependent upon expression of TFAP2C, and dual KD of RET and EGFR eliminated the effects of vandetanib. The response of primary luminal breast cancers to TKIs assessed by ERK activation established a correlation with expression of RET and EGFR. We conclude that TFAP2C regulates EGFR in luminal breast cancer. Response to vandetanib was mediated through the TFAP2C target genes EGFR and RET. Vandetanib may provide a therapeutic effect in luminal breast cancer, and RET and EGFR can serve as molecular markers for response.

[STUDY OF SAFETY OF PAROTITIS VACCINE]

AIM

Monitoring of post-vaccinal complications in children immunized with a parotitis vaccine.

MATERIALS AND METHODS

Observation of 198 945 children, immunized with 16 lots of parotitis vaccine with Leningrad-3 strain (L-3), was carried out for 3 years. Paired samples of sera and saliva were obtained from children, in whom adverse events were registered for 42 days after vaccination. Titers of specific IgM and IgG were determined in blood sera. Analysis of nucleotide sequences of genes F, SH and NH of RNA of parotitis virus was carried out from samples of blood and saliva.

RESULTS

Intensive parameter of vaccine-associated aseptic meningitis under the conditions of the experiments was 0 for 100 000 immunized. Frequency of occurrence of post-vaccinal parotitis was 0.06% from the number of vaccinated--18 cases of vaccine-associated parotitis were registered and laboratory confirmed. A significant difference in specific activity was detected for 3 lots of the vaccine, that were associated with cases of development of parotitis, relative to that of 13 lots of vaccine, development of parotitis was not registered after administration of those.

CONCLUSION

The study carried out confirmed low neurovirulence of the parotitis vaccine with the L-3 strain of parotitis virus, as well as a low degree of its reactogenicity. A relatively high immunization dose of the used vaccine could be one of the reasons of development of post-vaccinal complications in part of the immunized children.

Receptor Tyrosine Kinase Expression Predicts Response to Sunitinib in Breast Cancer

BACKGROUND

Preliminary data indicate that tyrosine kinase inhibitors (TKIs) function through rearranged during transfection (RET) in breast cancer. However, TKIs are not specific and can block several receptor tyrosine kinases (RTKs). This study used cell lines and primary breast cancer specimens to determine factors associated with TKI response.

METHODS

Proliferation was assessed after short interfering RNA knockdown with or without sunitinib in breast cancer cell lines by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide). Breast cancer tissue and matched normal breast was obtained from 30 women with invasive breast carcinoma. Gene expression was assessed by reverse transcriptase-polymerase chain reaction. Fresh tissue was treated in vitro with sunitinib or control media for 30 min, and response was assessed by phosphorylation-specific western blot.

RESULTS

The RTKs including epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor (VEGFR1-3), platelet-derived growth factor receptor (PDGFRa/b), and Kit were overexpressed in triple-negative breast tumors relative to HER2- and estrogen receptor-alpha (ERα)-positive tumors and normal breast tissue. Knockdown of EGFR reduced in vitro proliferation in MCF-7 and MDA-MB-231 but not in SKBR-3 or ZR-75-1 breast cancer cells. With the exception of RET, response to sunitinib was independent of RTK expression in all four cell lines. Both ERα-positive and low-EGFR-expressing tumors had an increased in vitro sunitinib response, as determined by alteration of Erk activation. Expression of other RTKs and additional clinical factors were not associated with response.

CONCLUSION

Triple-negative breast cancers overexpress RTKs but have decreased in vitro response to the TKI sunitinib. In addition to RET, TKIs that block EGFR may increase the therapeutic efficacy of TKIs in breast cancer.

A novel animal model for locally advanced breast cancer

BACKGROUND

Locally advanced breast cancer (LABC) poses complex management issues due to failure of response to chemotherapy and progression to local complications such as skin erosion, superinfection, and lymphedema. Most cell line and animal models are not adequate to study LABC.

METHODS

A patient-derived xenograft (IOWA-1T) from a patient with LABC was characterized for expression profile, short tandem repeat profile, oncogenic mutations, xenograft growth, and response to therapy.

RESULTS

Short tandem repeat profile authenticated the cell line as derived from a human woman. The primary tumor and derived xenografts were weakly estrogen receptor alpha positive (<5%), progesterone receptor negative, and HER2 nonamplified. Expression array profile compared to MCF-7 and BT-549 cell lines indicate that IOWA-1T was more closely related to basal breast cancer. IOWA-1T harbors a homozygous R248Q mutation of the TP53 gene; in vitro invasion assay was comparable to BT-549 and greater than MCF-7. IOWA-1T xenografts developed palpable tumors in 9.6 ± 1.6 days, compared to 49 ± 13 days for parallel experiments with BT-20 cells (p < 0.002). Tumor xenografts became locally advanced, growing to >2 cm in 21.6 ± 2 days, characterized by skin erosion necessitating euthanasia. The SUMO inhibitor anacardic acid inhibited the outgrowth of IOWA-1T xenografts, while doxorubicin had no effect on tumorigenesis.

CONCLUSIONS

IOWA-1T is a novel cell line with an expression pattern consistent with basal breast cancer. Xenografts recapitulated LABC and provide a novel model for testing therapeutic drugs that may be effective in cases resistant to conventional chemotherapy.

Sumoylation pathway is required to maintain the basal breast cancer subtype

The TFAP2C/AP-2γ transcription factor regulates luminal breast cancer genes, and loss of TFAP2C induces epithelial-mesenchymal transition. By contrast, the highly homologous family member, TFAP2A, lacks transcriptional activity at luminal gene promoters. A detailed structure-function analysis identified that sumoylation of TFAP2A blocks its ability to induce the expression of luminal genes. Disruption of the sumoylation pathway by knockdown of sumoylation enzymes, mutation of the SUMO-target lysine of TFAP2A, or treatment with sumoylation inhibitors induced a basal-to-luminal transition, which was dependent on TFAP2A. Sumoylation inhibitors cleared the CD44(+/hi)/CD24(-/low) cell population characterizing basal cancers and inhibited tumor outgrowth of basal cancer xenografts. These findings establish a critical role for sumoylation in regulating the transcriptional mechanisms that maintain the basal cancer phenotype.

Inhibition of RET increases the efficacy of antiestrogen and is a novel treatment strategy for luminal breast cancer

PURPOSE

Recent findings suggest that combination treatment with antiestrogen and anti-RET may offer a novel treatment strategy in a subset of patients with breast cancer. We investigated the role of RET in potentiating the effects of antiestrogen response and examined whether RET expression predicted the ability for tyrosine kinase inhibitor (TKI) to affect extracellular signal-regulated kinase 1/2 (ERK1/2) activation in primary breast cancer.

EXPERIMENTAL DESIGN

Growth response, ERK1/2 activation, Ki-67, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were assessed in breast cancer cell lines in vitro and in xenografts with vandetanib and/or tamoxifen. Thirty tumors with matched normal breast tissue were evaluated for RET expression and response to TKI treatment.

RESULTS

Vandetanib potentiated the inhibitory effect of tamoxifen in hormone responsive (P = 0.01) and hormone insensitive (P < 0.001) estrogen receptor α (ERα)-positive breast cancer cells. Vandetanib significantly repressed tumorigenesis of MCF-7 xenografts (P < 0.001), which displayed decreased activation of ERK1/2 and AKT. Vandetanib and tamoxifen reduced the growth of established tumors with a greater effect of dual therapy compared with single agent (P = 0.003), with tamoxifen-reducing proliferative index and vandetanib-inducing apoptosis. In primary breast cancers, RET expression correlated with the ERα-positive subtype. Relative decrease in ERK1/2 phosphorylation with TKI treatment was 42% (P < 0.001) in RET-positive tumors versus 14% (P = ns) in RET-negative tumors.

CONCLUSIONS

Vandetanib potentiated the antigrowth effects of tamoxifen in breast cancer, which was mediated through RET activation. RET predicted response to TKI therapy with minimal effects on ERK1/2 activation in RET-negative tumors. The preclinical data support evaluation of antiestrogen in combination with TKI as a potential treatment strategy for RET-positive luminal breast cancer.

TFAP2C governs the luminal epithelial phenotype in mammary development and carcinogenesis

Molecular subtypes of breast cancer are characterized by distinct patterns of gene expression that are predictive of outcome and response to therapy. The luminal breast cancer subtypes are defined by the expression of ER-alpha (ERα)-associated genes, many of which are directly responsive to the Transcription Factor Activator Protein 2C (TFAP2C). TFAP2C participates in a gene regulatory network controlling cell growth and differentiation during ectodermal development and regulating ESR1/ERα and other luminal cell-associated genes in breast cancer. TFAP2C has been established as a prognostic factor in human breast cancer, however, its role in the establishment and maintenance of the luminal cell phenotype during carcinogenesis and mammary gland development have remained elusive. Herein, we demonstrate a critical role for TFAP2C in maintaining the luminal phenotype in human breast cancer and in influencing the luminal cell phenotype during normal mammary development. Knockdown of TFAP2C in luminal breast carcinoma cells induced EMT with morphological and phenotypic changes characterized by a loss of luminal-associated gene expression and a concomitant gain of basal-associated gene expression. Conditional knockout of the mouse homolog of TFAP2C, Tcfap2c, in mouse mammary epithelium driven by MMTV-Cre promoted aberrant growth of the mammary tree leading to a reduction in the CD24^hi/CD49f^mid luminal cell population and concomitant gain of the CD24^mid/CD49f^hi basal cell population at maturity. Our results establish TFAP2C as a key transcriptional regulator for maintaining the luminal phenotype in human breast carcinoma. Furthermore, Tcfap2c influences development of the luminal cell type during mammary development. The data suggest that TFAP2C plays an important role in regulated luminal specific genes and may be a viable therapeutic target in breast cancer.

[Mumps vaccine virus transmission]

In this work we report the mumps vaccine virus shedding based on the laboratory confirmed cases of the mumps virus (MuV) infection. The likely epidemiological sources of the transmitted mumps virus were children who were recently vaccinated with the mumps vaccine containing Leningrad-Zagreb or Leningrad-3 MuV. The etiology of the described cases of the horizontal transmission of both mumps vaccine viruses was confirmed by PCR with the sequential restriction analysis.

High TFAP2C/low CD44 expression is associated with an increased rate of pathologic complete response following neoadjuvant chemotherapy in breast cancer

BACKGROUND

In luminal breast cancer cell lines, TFAP2C regulates expression of key genes in the estrogen receptor-associated cluster and represses basal-associated genes including CD44. We examined the effect of TFAP2C overexpression in a basal cell line and characterized the expression of TFAP2C and CD44 in breast cancer specimens to determine if expression was associated with clinical response.

METHODS

MDA-MB-231 breast cancer cells were treated with a TFAP2C-containing plasmid and evaluated for effects on CD44 expression. Pretreatment biopsy cores from patients receiving neoadjuvant chemotherapy for breast cancer were evaluated for TFAP2A, p53, TFAP2C, and CD44 expression by immunohistochemistry.

RESULTS

Overexpression of TFAP2C in MDA-MB-231 cells resulted in decreased expression of CD44 mRNA and protein, P < 0.05. A pathologic complete response (pCR) following neoadjuvant chemotherapy was achieved in 17% of patients (4/23). Average expression for TFAP2C by immunohistochemistry in patients with a pCR was 93%, compared with 46% in patients with residual disease, P = 0.016; and in tumors that stained at ≥80% for TFAP2C, 4 of 9 (44%) achieved pCR, compared with 0 of 14 below 80%, P = 0.01. Additionally, in tumors that stained ≤80% for CD44, 4 of 10 (40%) achieved pCR, compared with 0 of 13 >80%, P = 0.02. In tumors that stained high for TFAP2C (≥80%) and low for CD44 (≤80%), 4 of 7 (57%) achieved pCR, compared with 0 of 16 in all other groups (P = 0.004).

CONCLUSIONS

TFAP2C repressed CD44 expression in basal-derived breast cancer. In primary breast cancer specimens, high TFAP2C and low CD44 expression were associated with pCR after neoadjuvant chemotherapy and could be predictive of tumors that have improved response to neoadjuvant chemotherapy.

Expression of the RET proto-oncogene is regulated by TFAP2C in breast cancer independent of the estrogen receptor

BACKGROUND

The RET proto-oncogene is expressed as part of the estrogen receptor (ER) cluster in breast cancer. We sought to determine if TFAP2C regulates Ret expression directly or indirectly through ER.

METHODS

Chromatin immunoprecipitation sequencing (ChIP-Seq) and gel-shift assay were used to identify TFAP2C binding sites in the RET promoter in four breast cancer cell lines. Ret mRNA and protein levels were evaluated in ER-positive and ER-negative breast cancer cell lines after knockdown of TFAP2C. Luciferase expression assay was performed to assess expression from two of the identified sites.

RESULTS

ChIP-Seq identified five main binding peaks for TFAP2C in the RET promoter at -101.5 kb, -50.7 kb, -32.5 kb, +5.0 kb, and +33.6 from the RET transcriptional start site. Binding at three of the AP-2 sites was conserved across all four cell lines, whereas the RET -101.5 and RET +33.6 sites were each found to be unbound by TFAP2C in one cell line. A TFAP2C consensus element was confirmed for all five sites. Knockdown of TFAP2C by siRNA in ER-positive MCF-7 cells resulted in significant down regulation of Ret mRNA compared to nontargeting (NT) siRNA (0.09 vs. 1.0, P < 0.001). Knockdown of TFAP2C in ER-negative MDA-MB-453 cells also led to a significant reduction in Ret mRNA compared to NT siRNA (0.16 vs. 1.0, P < 0.001). In MCF-7 cells, knockdown of TFAP2C abrogated Ret protein expression (0.02 vs. 1.0, P < 0.001) before reduction in ER.

CONCLUSIONS

TFAP2C regulates expression of the RET proto-oncogene through five AP-2 regulatory sites in the RET promoter. Regulation of Ret by TFAP2C occurs independently of ER expression in breast carcinoma.

[Monitoring for influenza in population of Western Siberia in 2007-2009]

AIM

To analyze influenza viruses isolated in the 2008-2009 autumn-winter season, and to test sera collected in the south of Western Siberia during the beginning and the end of the epidemic seasons from 2007 until the A/H1N1 pandemic.

MATERIALS AND METHODS

Total 149 clinical samples were analyzed and 2190 blood sera were tested. During the 2008-2009 season 17 influenza viruses were isolated. 9 of these were A/H1N1, 5-were A/H3N2, and 3 were influenza B viruses. The nucleotide sequences and amino acid composition of influenza A virus hemagglutinin (HA) were compared with reference strains.

RESULTS

Among A/H1N1 viruses circulating in Novosibirsk region three viruses contained four amino acid replacements in antigen sites Ca, Cb and Sb. In A/ H3N2 viruses from Novosibirsk, 2 amino acid substitutions were detected in antigen sites B and E.

CONCLUSION

Based on genotyping influenzae epidemic on February to April of 2009 in the south of western Siberia was associated with influenza viruses A/H1N1, A/H3N2, and B. All A/H3N2 influenza virus isolates were variants of reference A/Brisbane/10/2007(H3N2) and A/ H1N1 influenza viruses isolates were similar to reference A/Brisbane/59/2007(H1N1).

Study of measles virus recombinant proteins and their immunobiological properties

Recombinant proteins rN (nucleocapsid) and rH/Nh (hemagglutinin) of the measles virus strain NovO/96 of genotype A were obtained. The immunobiological properties of the proteins were studied in the reaction with a panel of positive and negative sera. BALB/c mice were immunized with recombinant proteins and native antigen of the measles virus strain NovO/96 in order to obtain hyperimmune serum and its analysis using ELISA (enzyme-linked immunosorbent assay) and PRN (plaque reduction neutralization). The hyperimmune sera against recombinant proteins and native antigen of the measles virus strain NovO/96 were found to be highly active in ELISA. The antibodies against the proteins rN and rH/Nh were found to be capable of neutralizing the virus in titer 1 : 13.5 and 1 : 22.9, respectively. The neutralization titer of the antibodies generated against native antigen of the measles virus strain NovO/96 was 1 : 25.7.

Measles cases in highly vaccinated population of Novosibirsk, Russia, 2000-2005

While the proportion of measles cases in vaccinees is expected to increase as vaccine coverage increases, such cases must be carefully investigated. The present study was conducted to examine possible contributions to vaccine failures (VFs) and to genetically characterize measles virus (MV) strains circulating in Novosibirsk, Russia during 2000-2005. Totally, 27 adult measles patients admitted to a regional hospital were prospectively enrolled in our study. Genetic characterization of the MV strains revealed circulation of genotypes A, D4 and D6 between 2000 and 2003 years; a genotype D6 MV was associated with the 2005 measles outbreak. Based on IgG avidity testing, half of the vaccinated patients demonstrated evidence of secondary vaccine failure (SVF). Patients, representing both levels of vaccine failure in our study were characterized by the lack of protective titers of neutralizing antibodies against circulating MVs, despite high IgG levels in many cases and high IgG avidity in SVF cases.

[Isolation and study of the immunobiological properties of the recombinant proteins of measles virus]

Recombinant proteins rN (nucleocapsid) and rH/Nh (hemagglutinin) of the measles virus strain NovO/96 of genotype A were obtained. The immunobiological properties of the proteins were studied in the reaction with a panel of positive and negative sera. Mice of the line Balb/C were immunized with recombinant proteins and native antigen of the measles virus strain NovO/96 in order to obtain hyperimmune serum and its analysis using ELISA (enzyme-linked immunosorbent assay) and PRN (plaque reduction neutralization). The hyperimmune serum against recombinant proteins and native antigen of the measles virus strain NovO/96 were found to be highly active in ELISA. The antibodies against the proteins rN and rH/Nh were found to be able to neutralize the virus in titer 1:13.5 and 1:22.9, respectively. The neutralization titer of the antibodies generated against native antigen of the measles virus strain NovO/96 was 1:25.7.

Mumps vaccine failure investigation in Novosibirsk, Russia, 2002-2004

The aims of this study were to estimate the importance of vaccine failure (VF) in cases of mumps during 2002-2004 in the city of Novosibirsk, Western Siberia, Russia, and to genotype the responsible virus strain. Mumps virus-specific RT-PCR testing of saliva was performed for 18 cases of mumps. Sera were tested for IgM and IgG, IgG avidity, and the ability to neutralise a panel of mumps viruses, including the Leningrad-3 mumps vaccine virus. Of the 12 patients for whom vaccination status was positively determined, 11 showed serological evidence of primary VF. Sequence analysis of virus RNA amplified from saliva revealed a genotype C2 virus in 2002, a genotype H2 virus in 2003, and both genotypes in 2004. Although several vaccinated patients were positive for mumps virus IgG at the time of first sampling, only nominal levels of neutralising antibody were detected, and these were effective in neutralising the vaccine strain, but not genotype C and H mumps virus strains. These results suggest that the majority of cases of mumps in vaccinees are caused by primary VF, defined as either a lack of seroconversion or a lack of IgG maturity, as based on avidity testing. The results also support the hypothesis that sera of low neutralising antibody titre have a limited ability to neutralise heterologous mumps virus strains, suggesting that antigenic differences between circulating and mumps vaccine virus strains may play a role in cases of breakthrough infection. Consistent with previous reports, mumps virus genotypes C and H continue to circulate in Novosibirsk.