Karen K. L. Chan

Loss of MKP3 mediated by oxidative stress enhances tumorigenicity and chemoresistance of ovarian cancer cells

The RAS-RAF-MEK-extracellular signal-regulated kinase (ERK) pathway plays a pivotal role in various cellular responses, including cellular growth, differentiation, survival and motility. Constitutive activation of the ERK pathway has been linked to the development and progression of human cancers. Here, we reported that mitogen-activated protein kinase phosphatase (MKP)-3, a negative regulator of ERK1/2, lost its expression particularly in the protein level, was significantly correlated with high ERK1/2 activity in primary human ovarian cancer cells using quantitative reverse transcription-polymerase chain reaction and western blot analyses. Intriguingly, the loss of MKP3 protein was associated with ubiquitination/proteosome degradation mediated by high intracellular reactive oxygen species (ROS) accumulation such as hydrogen peroxide in ovarian cancer cells. Functionally, short hairpin RNA knock down of endogenous MKP3 resulted in increased ERK1/2 activity, cell proliferation rate, anchorage-independent growth ability and resistance to cisplatin in ovarian cancer cells. Conversely, enforced expression of MKP3 in MKP3-deficient ovarian cancer cells significantly reduced ERK1/2 activity and inhibited cell proliferation, anchorage-independent growth ability and tumor development in nude mice. Furthermore, the enforced expression of MKP3 succeeded to sensitize ovarian cancer cells to cisplatin-induced apoptosis in vitro and in vivo. These results suggest a molecular mechanism by which the accumulation of ROS during ovarian cancer progression may cause the degradation of MKP3, which in turn leads to aberrant ERK1/2 activation and contributes to tumorigenicity and chemoresistance of human ovarian cancer cells.

Estrogen Receptor Subtypes in Ovarian Cancer : A Clinical Correlation

OBJECTIVE: To study the distribution of estrogen receptor (ER) subtypes in ovarian tumors and to correlate the levels of expression with clinical factors. METHODS: Estrogen receptor-&agr; (ER&agr;) and &bgr;-mRNA expressions in 58 normal, 25 borderline, and 161 malignant ovarian tissue samples were determined by quantitative real-time polymerase chain reaction. The expression levels were correlated with clinical data, including the histologic subtypes, the stage of the disease, and the disease-free and overall survival, with a median follow-up of 80 months. RESULTS: Estrogen receptor-&bgr; (ER&bgr;) expression, but not ER&agr;, was significantly higher in normal tissues compared with malignant tissues (P<.001). Estrogen receptor-&bgr; expression was also significantly higher in stage I disease compared with stage II-IV disease (P<.001). A higher ER&bgr; expression was found to be significantly associated with a longer disease-free survival (P=.007) as well as overall survival (P=.011). Estrogen receptor-&bgr; expression remained a significant predictor for disease-free survival and overall survival in multivariable analysis that took into account other factors that were shown to be associated with survival in univariate analyses, including stage of disease, type of tumor (borderline or malignant), and optimal debulking. CONCLUSION: Loss of ER&bgr; expression in ovarian tumors may be a feature of malignant transformation. Determining ER subtypes expression may improve response to hormonal therapy by tailoring the use of selective estrogen receptor modulators with different ER affinity in selected women. As a prognostic indicator, ER&bgr; levels may be useful in deciding the need for and choice of adjuvant treatment in women with early ovarian cancers. LEVEL OF EVIDENCE: II

Evaluation of a Newly Developed GenoArray Human Papillomavirus (HPV) Genotyping Assay and Comparison with the Roche Linear Array HPV Genotyping Assay

ABSTRACT Persistent infection with high-risk types of human papillomavirus (HPV) is a necessary step in the development of cervical cancer. The incorporation of HPV detection into cervical screening programs may improve the ability to identify women at risk of cervical cancer. We recently evaluated the performance characteristics of a newly developed HPV detection assay, the GenoArray (GA) genotyping assay, for the detection of HPV infections by comparing it with the commercial Roche Linear Array (LA) HPV genotyping assay. The GA assay has an analytical sensitivity for the detection of HPV types 16 (HPV-16) and HPV-18 of as few as 10 to 50 copies, and its reproducibility is adequate. The GA and LA assays showed no significant difference in the rates of detection of genotypes detected by both HPV genotyping assays and oncogenic genotypes, and the interassay agreement was excellent. The GA and LA assays revealed either concordant or compatible genotyping results for 97.5% of the samples and discordant results for only eight (2.5%) samples. Compatible results were also observed for the detection of single or multiple HPV infections and the detection of most of the genotypes. The GA assay also demonstrated good clinical performance characteristics when the comparisons were carried out with clinical subgroups of samples from patients with normal cytologies, low-grade or high-grade squamous intraepithelial lesions, and cancers. Therefore, the GA assay appears to be highly sensitive and specific for the genotyping of HPV. It has the advantage that it specifically detects HPV-52, which overcomes a limitation of the LA assay, and hence, it has potential value for use for genotyping, especially in regions where HPV-52 has a high prevalence.

Iron supplement in pregnancy and development of gestational diabetes - A randomised placebo-controlled trial

Objective  To test the hypothesis that iron supplement from early pregnancy would increase the risk of gestational diabetes mellitus (GDM).

The use of HE4 in the prediction of ovarian cancer in Asian women with a pelvic mass

OBJECTIVE The purpose of this study was to evaluate the performance of human epididymis protein 4 (HE4) and the Risk of Ovarian Malignancy Algorithm (ROMA) for distinguishing between benign and malignant pelvis masses in Asian women. METHODS This was a prospective, multicenter (n=6) study with patients from six Asian countries. Patients had a pelvic mass on imaging and were scheduled to undergo surgery. Serum CA125 and HE4 were measured on preoperative samples. CA125, HE4, and ROMA were evaluated for sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). RESULTS A total of 414 women with an adnexal mass were evaluated, of which 65 had epithelial ovarian (EOC) cancer, 16 had borderline tumors and 11 had other malignant diseases. Compared to CA125, HE4 had lower sensitivity (56.9% vs 90.8%) and NPV (91.8% vs 97.3%), but improved specificity (96.9% vs 67.1%) and PPV (78.7% vs 35.8%) for differentiating between benign pelvic mass and EOC. ROMA had similar sensitivity (89.2% vs 90.8%) and NPV (97.6% vs 97.3%) as CA125, but showed improved specificity (87.3% vs 67.1%) and PPV (58.6% vs 35.8%). ROMA accurately predicted 87.3% of benign cases as low risk, and 82.6% of stage I/II EOC and 89.2% of all EOC as high risk. CONCLUSION ROMA showed similar sensitivity as CA125 but improved specificity and PPV, especially in premenopausal women. Using ROMA may help predict if a pelvic mass is benign or malignant and facilitate subsequent management planning.

Comparison of three‐dimensional hysterosalpingo‐contrast‐sonography and diagnostic laparoscopy with chromopertubation in the assessment of tubal patency for the investigation of subfertility

Background.  Two‐dimensional hysterosalpingo‐contrast‐sonography, as a screening test for tubal patency for subfertile patients, is limited by the difficulty in visualizing the entire Fallopian tube owing to its tortuosity. This major disadvantage can be overcome by means of the three‐dimensional hysterosalpingo‐contrast‐sonography (3D‐HyCoSy). The current study compared the efficacy of 3D‐HyCoSy with diagnostic laparoscopy and its feasibility as a screening test for tubal patency.

Tumour suppressive function and modulation of programmed cell death 4 (PDCD4) in ovarian cancer.

Background Programmed cell death 4 (PDCD4), originally identified as the neoplastic transformation inhibitor, was attenuated in various cancer types. Our previous study demonstrated a continuous down-regulation of PDCD4 expression in the sequence of normal-borderline-malignant ovarian tissue samples and a significant correlation of PDCD4 expression with disease-free survival. The objective of the current study was to further investigate the function and modulation of PDCD4 in ovarian cancer cells. Principal Findings We demonstrated that ectopic PDCD4 expression significantly inhibited cell proliferation by inducing cell cycle arrest at G1 stage and up-regulation of cell cycle inhibitors of p27 and p21. Cell migration and invasion were also inhibited by PDCD4. PDCD4 over-expressing cells exhibited elevated phosphatase and tensin homolog (PTEN) and inhibited protein kinase B (p-Akt). In addition, the expression of PDCD4 was up-regulated and it was exported to the cytoplasm upon serum withdrawal treatment, but it was rapidly depleted via proteasomal degradation upon serum re-administration. Treatment of a phosphoinositide 3-kinase (PI3K) inhibitor prevented the degradation of PDCD4, indicating the involvement of PI3K-Akt pathway in the modulation of PDCD4. Conclusion PDCD4 may play a critical function in arresting cell cycle progression at key checkpoint, thus inhibiting cell proliferation, as well as suppressing tumour metastasis. The PI3K-Akt pathway was implied to be involved in the regulation of PDCD4 degradation in ovarian cancer cells. In response to the stress condition, endogenous PDCD4 was able to shuttle between cell compartments to perform its diverted functions.

The use of Chinese herbal medicine to improve quality of life in women undergoing chemotherapy for ovarian cancer: a double-blind placebo-controlled randomized trial with immunological monitoring

BACKGROUND This study aimed to evaluate traditional Chinese medicine (TCM) in improving quality of life (QOL), reducing chemotoxicity and modulating immune function in patients undergoing chemotherapy. PATIENTS AND METHODS Patients with ovarian cancer were randomized to receive either TCM or placebo in addition to standard chemotherapy. The primary outcome was global health status (GHS) score, assessed by European Organization for Research and Treatment of Cancer questionnaire, while the secondary outcomes were other QOL items, chemotoxicity according to World Health Organization criteria and alterations in immune function as measured by immune cells count and the numbers of cytokines-secreting cells. RESULTS There was no significant difference in the GHS between the two groups. With adjustment for stage, chemotherapy type, disease status, age and baseline value, emotional function, cognitive function and nausea and vomiting were found to be worse or less improved in the TCM group compared with placebo group after six cycles of chemotherapy. The TCM group had less neutropenia after three cycles (0% grade 4 neutropenia versus 28.6%). There were no other significant differences in terms of chemotoxicity. Lymphocyte counts and cytokine activities decreased less in the TCM group. CONCLUSIONS TCM did not improve QOL but did have some effects in terms of maintaining immune function.

Relationship between intravoxel incoherent motion diffusion‐weighted MRI and dynamic contrast‐enhanced MRI in tissue perfusion of cervical cancers

To investigate the relationship between intravoxel incoherent motion (IVIM) diffusion‐weighted magnetic resonance imaging (MRI) and dynamic contrast‐enhanced MRI (DCE‐MRI) in cervical cancer perfusion.

Targeting GRB7/ERK/FOXM1 Signaling Pathway Impairs Aggressiveness of Ovarian Cancer Cells

Ovarian cancer is a highly lethal disease with poor prognosis and especially in high-grade tumor. Emerging evidence has reported that aberrant upregulation and activation of GRB7, ERK as well as FOXM1 are closely associated with aggresivenesss of human cancers. However, the interplay between these factors in the pathogenesis of human cancers still remains unclear. In this study, we found that GRB7 (P<0.0001), ERK phosphorylation (P<0.0001) and FOXM1 (P = 0.001) were frequently increased and associated with high-grade tumors, as well as a high tendency in association with advanced stage ovarian cancer by immunohistochemical analysis. Intriguingly, the expressions of GRB7 (P<0.0001), ERK phosphorylation (P<0.001) and FOXM1 (P<0.001) showed a significant stepwise increase pattern along Grade 1 to Grade 3 ovarian cancers. Biochemical studies using western blot analysis demonstrated that enforced expression or knockdown of GRB7 showed GRB7 could elevate the levels of ERK phosphorylation and FOXM1, whereas enforced expression of FOXM1 could not alter levels of GRB7 and ERK phosphorylation. But inhibition of ERK signaling by U0126 or PD98059 could reduce the level of FOXM1 in GRB7-overexpressing ovarian cancer cells, suggesting that GRB7, ERK and FOXM1 are regulated orderly. Moreover, inhibition of ERK activity by U0126 or PD98059, or decreased FOXM1 expression by Thiostrepton significantly inhibited cell migration/invasion, tumor growth in vitro and in vivo. Collectively, our findings confer that targeting GRB7/ERK/FOXM1 signaling cascade may be a promising molecular therapeutic choice in combating ovarian cancer.