miR-375 is upregulated in acquired paclitaxel resistance in cervical cancer

Background:

Chemo-resistance is one of the key causal factors in cancer death and emerging evidences suggest that microRNAs (miRNAs) have critical roles in the regulation of chemo-sensitivity in cancers. Cervical cancer is one of the most common malignancies in women and insensitive to chemotherapy clinically.

Methods:

The differentially expressed miRNAs in cervical squamous cell carcinoma tissues were screened by using a microarray platform (μParaflo Sanger miRBase release 13.0). The expression of miR-375 was determined by stem-loop RT–PCR using 23 clinical cervical cancer samples and 2 cervical cancer cell lines. We exogenously upregulated miR-375 expression in SiHa and Caski cells using a pre-miRNA lentiviral vector transfection and observed its impact on paclitaxel sensitivity using MTS. The cells that stably overexpressed miR-375 were subcutaneously injected into mice to determine tumour growth and chemo-sensitivity in vivo.

Results:

Twenty-one differentially expressed miRNAs were found by miRNA microarray between pro- and post-paclitaxel cervical cancer tissues. Of those, miR-375 showed consistent high expression levels across paclitaxel-treated cervical cells and tissues. Paclitaxel induced upregulated miR-375 expression in a clear dose-dependent manner. Forced overexpression of miR-375 in cervical cancer cells decreased paclitaxel sensitivity in vitro and in vivo.

Conclusion:

Collectively, our results suggest that miR-375 might be a therapeutic target in paclitaxel-resistant cervical cancer.

Lack of mutations of G4.5 in three families from China with noncompaction of the ventricular myocardium

To find the underlying cause of noncompaction of the ventricular myocardium (NVM), three Chinese families with probands who presented this problem were studied. After the family members were evaluated by echocardiography, the gene G4.5 (taffazin) was scanned by sequencing. Although X-linked inheritance could not be ruled out, NVM were thought to have a vague rule of inheritance in our data from 8 patients and 28 family members. We also did not identify any mutations in G4.5 in all samples. Our data suggest that other genes are responsible for the familial form of this disease.

Successive magnetic phase transitions and multiferroicity in the spin-one triangular-lattice antiferromagnet Ba3NiNb2O9

We report the magnetic and electric properties of Ba3NiNb2O9, which is a quasi-two-dimensional spin-one triangular-lattice antiferromagnet with trigonal structure. At low T and with increasing magnetic field, the system evolves from a 120 degree magnetic ordering phase (A phase) to an up-up-down (uud) phase (B phase) with a change of slope at 1/3 of the saturation magnetization, and then to an "oblique" phase (C phase). Accordingly, the ferroelectricity switches on at each phase boundary with appearance of spontaneous polarization. Therefore, Ba3NiNb2O9 is a unique triangular-lattice antiferromagnet exhibiting both uud phase and multiferroicity.

Abstract P2-05-19: Pathway-based analysis of breast cancer

Objective: Although HER2 and ER pathways are predominant pathways altered in breast cancer, it is now well accepted that many other signaling pathways are also involved in the pathogenesis of breast cancer, especially in triple negative breast cancer. The understanding of these additional pathways may assist in identifying new therapeutic approaches for breast cancer.

Methods: 13 invasive ductal carcinoma tissues and 5 benign breast tissues were analyzed for the mRNA expression level of 1243 cancer pathway-related genes using SmartChip (WaferGen, CA), a real-time PCR-base method. In addition, the levels of 154 cancer pathway-related proteins and phosphoproteins were measured using our innovative Protein Pathway Array.

Results: Out of 1,243 mRNAs, 68.7% were detected in breast cancer and 73 mRNAs were statistically significant between benign and cancer tissues. Of these mRNAs, 105 only expressed in breast cancer tissues and 33 mRNAs only expressed in normal breast tissues. Out of 154 proteins and phosphoproteins, 39% were detected in cancer tissues and 50 proteins were significantly differentiated between tumor and normal tissues. Interestingly, only 3 genes (CDK6, Vimentin and SLUG) showed decrease of both protein and mRNA. Six proteins (BCL6, CCNE1, PCNA, PDK1, SRC and XIAP) showed differentially expressed between tumor and normal tissues but no differences were observed at mRNA levels. Analyses of mRNA and protein data using Ingenuity Pathway Analysis showed more 15 pathways were altered in breast cancers and 6 of them shared between mRNAs and proteins, including p53, IL17, HGF, NGF, PTEN and PI3K/AKT.

Conclusion: There is a broad dysregulation of various pathways in breast cancer both at protein levels and mRNA levels. It is important to note that mRNA expression does not correlate with protein level, suggesting that different regulation mechanisms between proteins and mRNAs.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-05-19.

Evaluation of comprehensive two-dimensional gas chromatography-time-of-flight-mass spectrometry for the analysis of polycyclic aromatic hydrocarbons in sediments

This study evaluates the feasibility of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-ToF MS) for the determination of the 15+1 EU PAHs in sediments. Experimental variables affecting the injection, chromatographic separation and analytical detection of the analytes have systematically been optimised. Under finally proposed conditions, a satisfactory resolution among critical pairs/groups of PAHs, including benz[a]anthracene, cyclopenta[cd]pyrene and chrysene, the three benzofluoranthene isomers, indeno[1,2,3-cd]pyrene from dibenz[a,h]anthracene (DahA), and DahA from dibenz[a,c]anthracene, has been achieved using DB-5 × BPX-50 as column combination with a run time of 1 h. The feasibility of the method for the analysis of real-life samples has been demonstrated by accurate determination of relevant target PAHs in the certified harbour sediment BCR-535 (deviations among certified concentration values and those calculated using the proposed method lower than 3%); and by successful application to sediments sampled from a relevant protected area located in the South of Spain. The low methodological limits of detection (LODs) obtained for most of the targeted PAHs (in the 5.7-60 μg/kg range, as calculated for real samples) guarantied accurate quantification of the target compounds at the low levels expected in these types of pristine matrices. The strong retention experienced by the heaviest dibenzopyrene isomers included in the study resulted in relatively high LODs for these analytes; nevertheless, these compounds were detected at concentration levels above the corresponding LOD in some of the analysed sediments. In addition, the enhanced identification power provided by GC × GC-ToF MS for the identification of non-target analytes allowed the tentative identification of a group of polynuclear aromatic thiophenes in some of the test samples. Finally, the potential of the use of normalised bubble plots for the fast screening of the potential PAH sources has been demonstrated.

Suppressed miR-424 expression via upregulation of target gene Chk1 contributes to the progression of cervical cancer

MicroRNAs (miRNAs) act as important gene regulators in human genomes and their aberrant expression links to many malignancies. We previously identified a different characteristic miRNA expression profile in cervical cancer from that in cervical normal tissues, including the downregulated miR-424. However, the role and mechanism of miR-424 in cervical cancer still remain unknown. Here, we focused on identifying the tumor-suppressive function and clinical significance of miR-424 and exploring the mechanistic relevance by characterizing its target. We showed a significantly decreased expression of miR-424 in 147 cervical cancer tissues versus 74 cervical normal tissues by performing quantitative RT-PCR. In 147 cervical cancer tissue samples, low-level expression of miR-424 was positively correlated with poor tumor differentiation, advanced clinical stage, lymph node metastasis and other poor prognostic clinicopathological parameters. Further in vitro observations showed that enforced expression of miR-424 inhibited cell growth by both enhancing apoptosis and blocking G1/S transition, and suppressed cell migration and invasion in two human cervical cancer cell lines, SiHa and CaSki, implying that miR-424 functions as a tumor suppressor in the progression of cervical cancer. Interestingly, overexpression of miR-424 inhibited the expression of protein checkpoint kinase 1 (Chk1) and phosphorylated Chk1 (p-Chk1) at residues Ser345 and decreased the activity of luciferase-reporter containing the 3'-untranslated region (UTR) of Chk1 with predicted miR-424-binding site. Moreover, miR-424 expression levels were inversely correlated with Chk1 and p-Chk1 protein levels in both cervical cancer and normal tissues. Furthermore, RNAi-mediated knockdown of Chk1 decreased matrix metalloproteinase 9 expression and phenocopied the tumor suppressive effects of miR-424 in cell models. Taken together, our results identify a crucial tumor suppressive role of miR-424 in the progression of cervical cancer at least partly via upreglating the expression of Chk1 and p-Chk1, and suggest that miR-424 might be a candidate of prognostic predictor or an anticancer therapeutic target for cervical cancer patients.

Common crystalline and magnetic structure of superconducting A2Fe4Se5 (A=K,Rb,Cs,Tl) single crystals measured using neutron diffraction

Single-crystal neutron diffraction studies on superconductors A(2)Fe(4)Se(5), where A=Rb, Cs, (Tl, Rb), and (Tl, K) (T(c) ∼ 30 K), uncover the same Fe vacancy ordered crystal structure and the same block antiferromagnetic order as in K(2)Fe(4)Se(5). The Fe order-disorder transition occurs at T(S)=500-578 K, and the antiferromagnetic transition at T(N) = 471-559 K with an ordered magnetic moment ∼3.3μ(B)/Fe at 10 K. Thus, all recently discovered A intercalated iron selenide superconductors share the common crystalline and magnetic structure, which are very different from previous families of Fe-based superconductors, and constitute a distinct new 245 family.

An early decrease in serum HBeAg titre is a strong predictor of virological response to entecavir in HBeAg-positive patients

Quantification of HBeAg levels has been found to be useful in monitoring and predicting the outcomes of interferon and lamivudine treatment in HBeAg-positive patients. The aim of this study was to determine whether quantification of HBeAg at baseline and on treatment could predict which patients would achieve HBeAg seroconversion after 96 weeks of entecavir therapy. Sixty-five HBeAg-positive naïve chronic hepatitis B patients who were treated with entecavir at a dose of 0.5 mg once daily for 96 weeks were evaluated. Serum HBV DNA levels were assessed at baseline, week 24, 48 and 96; serum HBeAg levels were assessed at baseline, week 12, 24, 48, 72 and 96. Serum HBeAg levels were associated with a higher likelihood of HBeAg seroconversion to entecavir at weeks 96 than serum HBV DNA levels both at baseline and on treatment (at baseline: OR = 9.932, P = 0.003 vs. OR = 5.045, P = 0.036; on treatment: OR = 112.5, P < 0.0001 vs. OR = 47.782, P < 0.0001). A maintained reduction in HBeAg > 65% of pretreatment HBeAg values after 24 weeks of entecavir therapy is the strongest predictor for HBeAg seroconversion at week 96 (OR = 70.578, P < 0.0001). Quantification of HBeAg at the start and early during therapy showed a higher predictive value than that of HBV DNA for HBeAg seroconversion by entecavir. A significant decrease in serum HBeAg levels at week 24 may be a useful on-treatment measurement in the early phase for predicting HBeAg seroconversion and identifying patients who will most likely benefit from finite entecavir treatment.

Abstract S3-8: RNAi Screening Identifies the Insulin/Insulin-Like Growth Factor-I Receptor Pathway as a Mechanism of Escape from Hormone Dependence in Estrogen Receptor-Positive Breast Cancer

Estrogen receptor-positive (ER+) breast cancers are treated with strategies aimed at inducing estrogen deprivation such as aromatase inhibitors (AIs). However, many ER+ tumors adapt to hormone deprivation and acquire resistance to AIs. The purpose of this study was to identify kinases essential for the growth of endocrine-resistant ER+ breast cancer cells. To model acquired resistance to AIs, we maintained four ER+, estrogen-dependent human breast cancer cell lines (MCF-7, MDA-361, HCC-1428, and ZR75- 1) under hormone-depleted conditions for several months until hormone-independent populations emerged (termed long-term estrogen-deprived, LTED). We then performed an RNAi screen targeting 779 protein kinases to identify molecules required for growth of MCF-7/LTED cells in hormonefree conditions. Individual knockdown of 42 kinases significantly inhibited MCF-7/LTED cell growth ≥33% (p≥0.05) in at least 3/4 independent experiments. Of these 42 hits, knockdown of the insulin receptor (InsR) inhibited MCF-7/LTED growth (n=4 experiments) compared to control siRNA. Knockdown of InsR expression using independent siRNA oligonucleotides significantly inhibited growth of MCF-7/LTED, ZR75-1/LTED, and HCC-1428/LTED cells.

The InsR can heterodimerize with the highly homologous insulin-like growth factor-I receptor (IGF-IR) to potently activate the phosphatidylinositol-3 kinase (PI3K)/AKT signaling pathway. Immunoblot analysis revealed that siRNA knockdown of InsR or IGF-IR caused a compensatory upregulation of IGF-IR and InsR expression, respectively. Knockdown of InsR or IGF-IR inhibited growth of 3/4 LTED lines, but knockdown of both InsR and IGF-IR was required for maximal inhibition of PI3K/AKT. Inhibition of these receptors by treatment with the InsR/IGF-IR tyrosine kinase inhibitor (TKI) OSI-906 decreased PI3K signaling and disrupted the basal association between p85 and the IGF-IR/InsR effectors IRS-1 and IRS-2 in MCF-7/LTED cells. Further, OSI-906 inhibited the hormone-independent growth of all four LTED lines and prevented the emergence of hormone-independent ER+ parental cells following estrogen deprivation. Treatment with the TKI or the neutralizing IGF-IR monoclonal antibody MK-0646 induced feedback upregulation and phosphorylation of the ErbB3/HER3 receptor tyrosine kinase (RTK). Induction of P-HER3 was blocked by the EGFR/HER2 TKI lapatinib. Combined treatment of lapatinib and OSI-906 prevented the emergence of hormone-independent (HER2+/ER+) MDA-361 cells more effectively than either drug alone. Finally, treatment of ovariectomized nude female mice with OSI-906 suppressed the growth of established MCF-7 xenografts. In addition, treatment with OSI-906 decreased PI3K signaling as measured by immunoblot analysis of tumor extracts using P-AKT antibodies. These results suggest that 1) InsR/IGF-IR signaling is required for PI3K/AKT signaling and hormone-independent growth of ER+ breast cancer cells; 2) these cells compensate for the inhibition of InsR/IGF-IR by upregulating alternative RTK pathways such as HER3; 3) combined targeting of InsR/IGF-IR and ER signaling may be effective for the treatment of endocrine-resistant breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S3-8.

Abstract P6-05-05: Signaling Pathways Activated in Her 2 and ER Negative Breast Cancers

Introduction: Breast cancer is the most common cancer in women (192,370 new cases in 2009) and the second leading cause of cancer death (40,000) among women in USA. Current multimodality treatment of breast cancer is based on the level of ER expression and Her 2 gene amplification. However, no effective treatment is currently available for breast cancers with low level expression of ER and no amplification of Her 2 gene. The aim of this study is to identify protein pathways activated in the breast cancer with negative expression of ER and Her 2. Method: Protein Pathway Array was used to assess the level of protein expression and phosphorylation in 71 paired fresh frozen breast samples (tumor and adjacent benign tissue). A total 159 antibodies were evaluated which represent most important signal transduction pathways involved in proliferation, apoptosis, angiogenesis, invasion and metastasis. Several potential therapeutic kinase proteins were also assessed. Results: A total 20 proteins (PCNA, phospho-PTEN, cyclin B1 cyclin E1, CDK6, E-cadherin, NFkB, ect) were differentially expressed between normal and tumor tissues based on the statistical analysis. In Her 2 negative tumors (n=37), 3 proteins were differentially expressed and among them, 2 were up-regulated (CDK6 and HSD1) and 1 was down-regulated (IGF). In ER negative tumors (n=18), 4 proteins (HSD, SK, TDP and Slug) was up-regulated and 1 proteins were down-regulated (E-cadherin). In triple negative tumors (n=13), one protein (E-cadherin) down-regulated and 2 proteins (TDP and HSD) were up-regulated. Furthermore, based on the expression pattern of these proteins, tumors negative for both ER and Her 2 (n=15) can be clustered into 3 groups

Figure 1: Subclassification of breast cancers negative for ER and Her-2 based protein pattern.

Hierarchical clustering analysis of 20 differentially expressed proteins in

15 ER/Her-2 negative breast cancers. The cancers can be separated into 3 subtypes. Red indicates overexpression, green underexpression, black no change, and gray no expression. Each column represents a protein. Each row represents a sample.

Conclusion: Our study showed that distinct sets of signaling pathways activated in ER and Her 2 negative breast cancers. The increased expression of cell cycle progression proteins in Her 2 negative tumors suggests activation of cell proliferation via different growth promotion pathway. Similarly, different cell proliferation pathways are also activated in ER negative tumors. This finding may be used to design future clinical trial based on the activation of different signaling pathways.

Identification of cancer stem cell-like cells from human epithelial ovarian carcinoma cell line

Cancer stem cells (CSCs) play an important role in the development, invasion, and drug resistance of carcinoma, but the exact phenotype and characteristics of ovarian CSCs are still disputable. In this study, we identified cancer stem cell-like cells (CSC-LCs) and investigated their characteristics from the ovarian adenocarcinoma cell line 3AO. Our results showed that CSC-LCs were enriched in sphere-forming test and highly expressed CD44(+)CD24⁻. The spheres and CD24⁻ cells possessed strong tumorigenic ability by transplantation into nonobese diabetic/severe combined immunodeficient mice. CD44(+)CD24⁻ cells expressed stem cell markers and differentiated to CD44(+)CD24(+) cells by immunofluorescence assay and fluorescence-activated cell-sorting analysis. In vitro experiments verified that CD44(+)CD24⁻ cells were markedly resistant to carboplatin and paclitaxol. In conclusion, our study identifies the CD44(+)CD24⁻ phenotype, self-renewal, high tumorigenicity, differentiation potential, and drug resistance of ovarian CSC-LCs. Our findings may provide the evidence needed to explore a new strategy in the treatment of ovarian cancer.

Hand-assisted laparoscopic surgery versus the open approach in curative resection of rectal cancer

This prospective, randomized study compared the outcomes of hand-assisted laparoscopic surgery (HALS) with open surgery for the resection of rectal cancer. The main outcome measures were procedure time, blood loss, post-operative pain, time to oral intake, return of bowel function, length of hospital stay, morbidity and functional recovery. Patients in each group were similar with regard to general status, procedure types and the histopathological features of tumours. Procedure times were significantly longer with HALS versus open surgery. Analgesic requirements, surgical blood loss, time to first passing flatus, time to first oral fluids and post-operative hospital stay length were all significantly shorter in the HALS group. At a median follow-up of 16.3 months, local recurrence of tumour was not observed in either group. In this study, the HALS approach for curative resection of rectal cancer was safe and effective and may offer several potential advantages to patients in their post-operative recovery.

Subwavelength plasmonic lattice solitons in arrays of metallic nanowires

We predict theoretically that stable subwavelength plasmonic lattice solitons (PLSs) are formed in arrays of metallic nanowires embedded in a nonlinear medium. The tight confinement of the guiding modes of the metallic nanowires, combined with the strong nonlinearity induced by the enhanced field at the metal surface, provide the main physical mechanisms for balancing the wave diffraction and the formation of PLSs. As the conditions required for the formation of PLSs are satisfied in a variety of plasmonic systems, we expect these nonlinear modes to have important applications to subwavelength nanophotonics. In particular, we show that the subwavelength PLSs can be used to optically manipulate with nanometer accuracy the power flow in ultracompact photonic systems.

Electronic self-organization in the single-layer manganite Pr1-xCa1+xMnO4

We use neutron scattering to investigate the doping evolution of the magnetic correlations in the single-layer manganite Pr1-xCa1+xMnO4, away from the x=0.5 composition where the CE-type commensurate antiferromagnetic (AF) structure is stable. We find that short-range incommensurate spin correlations develop as the system is electron doped (x<0.5), which coexist with the CE-type AF order. This suggests that electron doping in this system induces an inhomogeneous electronic self-organization, where commensurate AF patches with x=0.5 are separated by electron-rich domain walls with short-range magnetic correlations. This behavior is strikingly different than for the perovskite Pr1-xCaxMnO3, where the long-range CE-type commensurate AF structure is stable over a wide range of electron or hole doping around x=0.5.

Gene silencing of HPV16 E6/E7 induced by promoter-targeting siRNA in SiHa cells

Background:

Recently, transcriptional gene silencing induced by small interfering RNA (siRNA) was found in mammalian and human cells. However, previous studies focused on endogenous genes.

Methods:

In this study, we designed siRNA targeting the promoter of human papillomavirus 16 E6/E7 and transfected it into the cervical cancer cell line, SiHa. E6 and E7 mRNA and protein expression were detected in cells treated by promoter-targeting siRNA. Futhermore, cellular growth, proliferation, apoptosis and senescence were detected. Thereafter, we investigated promoter DNA methylation and histone methylation status in cells treated with promoter-targeting siRNA.

Results:

We found that E6/E7 mRNA and protein were simultaneously reduced, cell growth and proliferation were inhibited and cell death, especially senescence, was remarkably increased. Meanwhile, we also found a significantly increasing histone H3-Lys9 methylation on the promoter when E6/E7 gene expression was inhibited.

Interpretation:

Our findings suggest that promoter-targeting siRNA effectively and simultaneously knocks down both extraneous HPV 16 E6 and E7 at the transcriptional level, and consequently inhibits proliferation and induces death in HPV 16-infected cells. This transcriptional repression is probably induced by histone modification rather than by alteration of DNA methylation.