Bei Zhang

Universität Basel, Basel, BS, Switzerland

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Publications (10)25.91 Total impact

  • Article: Antitumor properties of salinomycin on cisplatin-resistant human ovarian cancer cells in vitro and in vivo: involvement of p38 MAPK activation.
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    ABSTRACT: In order to search for alternative agents to overcome chemoresistance during the treatment of ovarian cancer, this study aimed to examine the anticancer effects and action mechanism of salinomycin, a selective inhibitor of cancer stem cells, on cisplatin-resistant human ovarian cancer cell lines in vitro and in vivo. The concentration- (0.01-200 µM) and time‑dependent (24-72 h) growth inhibitory effects of salinomycin were observed in the ovarian cancer cell lines OV2008, C13, A2780, A2780-cp, SKOV3 and OVCAR3, by measuring cell viability using the resazurin reduction assay. The IC50 (24 h) range of salinomycin on the six cell lines was found to be 1.7-7.4 µM. After cisplatin-resistant C13 cells were treated with salinomycin, the percentage of apoptotic cells determined by flow cytometry was significantly increased, in a concentration- and time‑dependent manner. However, no cell cycle arrest was detected in the G1/G0, S and G2/M phases in the salinomycin‑treated and control cells. The Bio-Plex phosphoprotein 5-plex assay (Akt, IκB-α, ERK1/2, JNK and p38 MAPK) demonstrated a marked time- and concentration‑dependent increase in the phosphorylation of p38 MAPK, subsequent to salinomycin treatment. Moreover, salinomycin significantly suppressed tumor growth in a tumor xenograft model. These findings suggested that salinomycin efficiently inhibits the cisplatin-resistant human ovarian cancer cell line growth through the induction of apoptosis, potentially asso-ciated with the p38 MAPK activation.
    Oncology Reports 01/2013; · 1.84 Impact Factor
  • Article: The level of circulating miRNA-10b and miRNA-373 in detecting lymph node metastasis of breast cancer: potential biomarkers.
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    ABSTRACT: MicroRNAs (miRNAs) are a class of small noncoding RNAs whose expression changes are associated with cancer development and invasion. We hypothesized that miR-10b and miR-373, which are increased in lymphatic metastatic tissues, could be directly assayed in the plasma and used to detect the lymph node status of breast cancer patients. Between November 2009 and January 2012, 35 breast ductal carcinoma patients with lymph node metastasis (N patients), 25 ductal carcinoma patients without lymph node metastasis (N(0) patients), and ten healthy female donors were enrolled in the study. Circulating miR-10b and miR-373 were determined in preoperative plasma samples by reverse transcription quantitative real-time PCR assay. In preliminary tests, the plasma levels of circulating miR-10b and miR-373 were found to be significantly higher in ten breast cancer patients with lymph node metastasis compared to ten N(0) patients and ten normal donors (P < 0.01). On validation analysis, the median value level of miR-10b in the 35 N patients was 4.44-fold (P < 0.01) increased, and miR-373 was 4.38-fold (P < 0.01) increased in comparison to the 25 N(0) patients. MiR-10b was used for differentiation of N patients from N(0) patients; the odds ratio was 2.19, and the value of the area under the receiver-operating curve (AUC) was 0.80, with sensitivity of 71 % and specificity of 72 %. For miR-373, the odds ratio was 2.62, and the AUC was 0.84, with sensitivity of 68 % and specificity of 89 %. A combination of the two circulating miRNAs further enhanced the sensitivity to 72 % and the specificity to 94.3 %. Our data suggest that circulating miRNA-10b and miRNA-373 are potential biomarkers for detecting the lymph node status of breast cancer.
    Tumor Biology 12/2012; · 1.94 Impact Factor
  • Article: Effects of salinomycin on human ovarian cancer cell line OV2008 are associated with modulating p38 MAPK.
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    ABSTRACT: This study investigated the anticancer effect and mechanism of salinomycin, a selective inhibitor of cancer stem cell, on human ovarian cancer cell line OV2008 in vitro and in vivo. The growth inhibitory effect of salinomycin on ovarian cancer cell line OV2008 was determined by measuring cell viability using the resazurin reduction assay. Apoptotic nuclear morphology was visualized by 4,6-diamino-2-phenylindole staining technique. The percentages of apoptotic cells and cell cycle parameters were detected by flow cytometry. The activity of p38 mitogen-activated protein kinase (p38 MAPK) was analyzed by Bio-Plex phosphoprotein assay. In vivo activity of salinomycin was assayed through tumor growth. Salinomycin caused concentration- (0.01-200 μM) and time-dependent (24-72 h) growth inhibitory effects in OV2008. Cell nuclear morphology observations showed that salinomycin-treated OV2008 cells displayed typical apoptotic characteristics. Salinomycin significantly increased the percentages of apoptotic cells in OV2008, showing a concentration- and time-dependent manner. There was no cell cycle arrest in the G1/G0, S, and G2/M phases between salinomycin-treated cells and control cells. Salinomycin also enhanced the phosphorylation of p38 MAPK. Moreover, salinomycin significantly inhibited the growth of the ovarian xenograft tumors. Salinomycin exhibited significant growth inhibition and induction of apoptosis in the human ovarian cancer cell line OV2008. The data suggested that salinomycin-induced apoptosis in OV2008 might be associated with activating p38 MAPK and merits further investigations.
    Tumor Biology 07/2012; · 1.94 Impact Factor
  • Article: Mutations of mitochondrial DNA as potential biomarkers in breast cancer.
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    ABSTRACT: Alterations of mitochondrial DNA (mtDNA) have been found in cancer patients, therefore informative mtDNA mutations could serve as biomarkers for the disease. The two hypervariable regions HVR1 and HVR2 in the D-Loop region were sequenced in ten paired tissue and plasma samples from breast cancer patients. MtDNA mutations were found in all patients' samples, suggesting a 100% detection rate. Examining germline mtDNA mutations, a total of 85 mutations in the D-loop region were found; 31 of these mutations were detected in both tissues and matched plasma samples, the other 54 germline mtDNA mutations were found only in the plasma samples. Regarding somatic mtDNA mutations, a total of 42 mutations in the D-loop region were found in breast cancer tissues. Somatic mtDNA mutations in the D-loop region were detected in breast cancer tissues but not in the matched plasma samples, suggesting that more sensitive methods will be needed for such detection to be of clinical utility.
    Anticancer research 12/2011; 31(12):4267-71. · 1.73 Impact Factor
  • Article: Strategies of reducing input sample volume for extracting circulating cell-free nuclear DNA and mitochondrial DNA in plasma.
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    ABSTRACT: Circulating cell-free (ccf) DNA in blood has been suggested as a potential biomarker in many conditions regarding early diagnosis and prognosis. However, misdiagnosis can result due to the limited DNA resources in Biobank's plasma samples or insufficient DNA targets from a predominant DNA background in genetic tests. This study explored several strategies for an efficient DNA extraction to increase DNA amount from limited plasma input. Ccf plasma DNA was extracted with three different methods, a phenol-chloroform-isoamylalcohol (PCI) method, a High Pure PCR Template Preparation Kit method and a method used for single cell PCR in this group. Subsequently, the total DNA was measured by Nanodrop and the genome equivalents (GE) of the GAPDH housekeeping gene and MTATP 8 gene were measured using a multiplex real-time quantitative PCR for the quantitative assessment of nDNA and mtDNA. Instead of 400-800 μL (routine input in the laboratory), 50 μLof plasma input enabled the extraction of ccf DNA sufficient for quantitative analysis. Using the PCI method and the kit method, both nDNA and mtDNA could be successfully detected in plasma samples, but nDNA extracted using protocol for single cell PCR was not detectable in 25% of plasma samples. In comparison to the other two methods, the PCI method showed lower DNA purity, but higher concentrations and more GE of nDNA and mtDNA. The PCI method was more efficient than the other two methods in the extraction of ccf DNA in plasma. Limited plasma is available for ccf DNA analysis.
    Clinical Chemistry and Laboratory Medicine 10/2011; 50(2):261-5. · 2.15 Impact Factor
  • Article: An overview of biomarkers for the ovarian cancer diagnosis.
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    ABSTRACT: Even though there are a lot of options in treating gynecological malignancies, ovarian cancer still remains a leading cause of death. Diagnosis at an early stage is the most important determinant of survival. Current diagnostic tools applied at clinics have had very limited success in early detection. Discovery of new diagnostic biomarkers/panels for early diagnosis of ovarian cancer is one of the main challenges of modern medicine. With the progress of techniques in genomics and proteomics, numerous molecular biomarkers/panels were identified and showed promise for ovarian cancer diagnosis, but still need further validation. This article summarizes various types of markers investigated by different strategies/technologies for the ovarian cancer diagnosis at present, including gene-, protein-based and emerging ovarian cancer indicators (such as microRNA-, metabolite-based). Before biomarker tests are translated for routine use, more researches, such as retrospective and prospective clinical trials, are needed to evaluate the overall clinical utility of the tests.
    European journal of obstetrics, gynecology, and reproductive biology 05/2011; 158(2):119-23. · 1.97 Impact Factor
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    Article: Epigenetic therapy for breast cancer.
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    ABSTRACT: Both genetic and epigenetic alterations can control the progression of cancer. Genetic alterations are impossible to reverse, while epigenetic alterations are reversible. This advantage suggests that epigenetic modifications should be preferred in therapy applications. DNA methyltransferases and histone deacetylases have become the primary targets for studies in epigenetic therapy. Some DNA methylation inhibitors and histone deacetylation inhibitors are approved by the US Food and Drug Administration as anti-cancer drugs. Therefore, the uses of epigenetic targets are believed to have great potential as a lasting favorable approach in treating breast cancer.
    International Journal of Molecular Sciences 01/2011; 12(7):4465-87. · 2.60 Impact Factor
  • Article: Umbilical cord blood stem cells: what to expect.
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    ABSTRACT: Umbilical cord blood (UCB) is a valuable alternative source of hematopoietic stem cells (HSCs). It has unique advantages of easy procurement, absence of risk to donors, low risk of transmitting infections, immediate availability, greater tolerance of human leukocyte antigen (HLA) disparity, and lower incidence of inducing severe graft-versus-host disease (GVHD). In the last several years, these features of UCB permit the field of UCB transplantation (UCBT) to move at a faster pace for both children and adults with malignancies and nonmalignancies. However, new strategies and novel developments are expected to improve engraftment and reconstitution, and to enable in utero transplantation for early therapy, as well as to allow the therapy for a wide spectrum of human diseases.
    Annals of the New York Academy of Sciences 09/2010; 1205:17-22. · 3.15 Impact Factor
  • Article: Methylation profile of TP53 regulatory pathway and mtDNA alterations in breast cancer patients lacking TP53 mutations.
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    ABSTRACT: The present study investigated promoter hypermethylation of TP53 regulatory pathways providing a potential link between epigenetic changes and mitochondrial DNA (mtDNA) alterations in breast cancer patients lacking a TP53 mutation. The possibility of using the cancer-specific alterations in serum samples as a blood-based test was also explored. Triple-matched samples (cancerous tissues, matched adjacent normal tissues and serum samples) from breast cancer patients were screened for TP53 mutations, and the promoter methylation profile of P14(ARF), MDM2, TP53 and PTEN genes was analyzed as well as mtDNA alterations, including D-loop mutations and mtDNA content. In the studied cohort, no mutation was found in TP53 (DNA-binding domain). Comparison of P14(ARF) and PTEN methylation patterns showed significant hypermethylation levels in tumor tissues (P < 0.05 and <0.01, respectively) whereas the TP53 tumor suppressor gene was not hypermethylated (P < 0.511). The proportion of PTEN methylation was significantly higher in serum than in the normal tissues and it has a significant correlation to tumor tissues (P < 0.05). mtDNA analysis revealed 36.36% somatic and 90.91% germline mutations in the D-loop region and also significant mtDNA depletion in tumor tissues (P < 0.01). In addition, the mtDNA content in matched serum was significantly lower than in the normal tissues (P < 0.05). These data can provide an insight into the management of a therapeutic approach based on the reversal of epigenetic silencing of the crucial genes involved in regulatory pathways of the tumor suppressor TP53. Additionally, release of significant aberrant methylated PTEN in matched serum samples might represent a promising biomarker for breast cancer.
    Human Molecular Genetics 05/2010; 19(15):2936-46. · 7.64 Impact Factor
  • Article: Proteomics and biomarkers for ovarian cancer diagnosis.
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    ABSTRACT: Ovarian cancer remains a leading cause of death from gynecological malignancy. Early diagnosis is the most important determinant of survival. Current diagnostic tools have had very limited success in early detection. In recent years, the advancing techniques for proteomics have accelerated the discovery of ovarian cancer biomarkers. Numerous proteomics-based molecular biomarkers/panels have been identified and hold great potential for diagnostic applications, but they need further development and validation. This article reviews recently published data on the diagnosis of ovarian cancer with proteomics, including the major proteomics technologies and promising strategies for biomarker discovery and development.
    Annals of clinical and laboratory science 01/2010; 40(3):218-25. · 0.96 Impact Factor