Mu Hsien Yu

Identification of novel DNA methylation markers in cervical cancer

Testing for DNA methylation has potential in cancer screening. Most previous studies of DNA methylation in cervical cancer used a candidate gene approach. The aim our study was to identify novel genes that are methylated in cervical cancers and to test their potential in clinical applications. We did a differential methylation hybridization using a CpG island (CGI) microarray containing 8640 CGI tags to uncover methylated genes in squamous cell carcinomas (SCC) of the uterine cervix. Pooled DNA from cancer tissues and normal cervical swabs were used for comparison. Methylation‐specific polymerase chain reaction, bisulfite sequencing and reverse transcription polymerase chain reaction were used to confirm the methylation status in cell lines, normal cervices (n = 45), low‐grade lesions (n = 45), high‐grade lesions (HSIL; n = 58) and invasive squamous cell carcinomas (SCC; n = 22 from swabs and n = 109 from tissues). Human papillomavirus (HPV) was detected using reverse line blots. We reported 6 genes (SOX1, PAX1, LMX1A, NKX6‐1, WT1 and ONECUT1) more frequently methylated in SCC tissues (81.5, 94.4, 89.9, 80.4, 77.8 and 20.4%, respectively) than in their normal controls (2.2, 0, 6.7, 11.9, 11.1 and 0%, respectively; p < 0.0001). Parallel testing of HPV and PAX1 methylation in cervical swabs confers an improved sensitivity than HPV testing alone (80% vs. 66%) without compromising specificity (63% vs. 64%) for HSIL/SCC. Testing PAX1 methylation marker alone, the specificity for HSIL/SCC is 99%. The analysis of these novel DNA methylations may be a promising approach for the screening of cervical cancers.

Epigenetic silencing of SFRP5 is related to malignant phenotype and chemoresistance of ovarian cancer through Wnt signaling pathway.

Oncogenic activation of the Wnt signaling pathway is common in cancers, but mutation of β‐catenin in ovarian cancer is rare. In addition to genetic events, epigenetic modification of secreted frizzled‐related protein (SFRP) family has been shown to be important in regulating Wnt signaling. Although high degree of homology is observed in the same family, different SFRPs may have opposing effects on the same process. We reported recently that a Wnt antagonist, SFRP5, is downregulated frequently through promoter hypermethylation and that this hypermethylation is associated with overall survival in ovarian cancer. The aim of this study was to analyze the function of SFRP5 in ovarian cancer. Functional assays including measuring cell proliferation, invasion, colony formation and xenograft were performed using ovarian cancer cell lines with overexpression of SFRP5 or a short hairpin RNA silencing. The methylation status of SFRP5 in relation to cisplatin resistance in ovarian cancer patients was analyzed. Restoration of the expression of SFRP5 attenuated Wnt signaling in ovarian cancer cells and suppressed cancer cell growth, invasion of cells and tumorigenicity in mice. These effects were independent of the canonical pathway. The expression of SFRP5 inhibited epithelial–mesenchymal transition (EMT). The restoration of SFRP5 downregulated AKT2 and sensitized ovarian cancer cells to chemotherapy. These effects are consistent with the poor response to platinum‐based chemotherapy in patients with methylation of SFRP5. Our data suggested that epigenetic silencing of SFRP5 leads to oncogenic activation of the Wnt pathway and contributes to ovarian cancer progression and chemoresistance through the TWIST‐mediated EMT and AKT2 signaling.

SFRP1 and SFRP2 suppress the transformation and invasion abilities of cervical cancer cells through Wnt signal pathway.

OBJECTIVESnAberrant activation of the Wnt/beta-catenin signaling pathway is common in human cancers, including cervical cancer. The secreted frizzled-related proteins (SFRPs) function as Wnt antagonists and play important implications in carcinogenesis. Recently, we have shown that SFRP1 and SFRP2 are frequently downregulated through promoter hypermethylation. However, the function of SFRP1 and SFRP2 in cervical cancer remains unclear.nnnMETHODSnTo improve our understanding of the role of SFRP1 and SFRP2 in cervical cancer cells, we use overexpression or shRNA approach in cervical cancer cell lines.nnnRESULTSnRestoration of the expression of SFRP1 and SFRP2 attenuated Wnt signaling in CaSki cells, decreased abnormal accumulation of free beta-catenin in the nucleus, and suppressed cancer cell growth. In addition, different statuses of beta-catenin accumulation in the cytoplasm of CaSki or HeLa3rd cells were observed, suggesting that different Wnt pathways are executed. Furthermore, we demonstrated that SFRP1 and SFRP2 enhance the expression of the epithelial marker E-cadherin, through inhibition of the expression of SLUG, TWIST and SNAIL, three transcription factors involved in the epithelial mesenchymal transition (EMT) program. Finally, in a xenograft animal model, we showed that SFRP1 suppresses tumorigenicity of cancer cells in vivo.nnnCONCLUSIONSnTaken together, these data strongly suggest that epigenetic silencing of SFRP genes leads to oncogenic activation of the Wnt pathway and contributes to cervical cancer progression through the EMT program.

Single nucleotide polymorphism at Fas promoter is associated with cervical carcinogenesis

The causal role of human papillomavirus (HPV) in cervical carcinogenesis is beyond reasonable questioning. The progression from HPV infection, squamous intraepithelial lesions (SIL) to squamous cell carcinomata (SCC), however, is very uncommon and inefficient. Host genetic factors that may confer the susceptibility of disease progression are largely unknown. Apoptosis is an important fail‐safe check for tumor development, in which Fas/FasL interaction contributes substantially. The purpose of our study is to test the hypothesis that an A/G polymorphism at −670 of Fas promoter with different transcriptional activity is associated with the risk for cervical neoplasia. A hospital‐based case‐control study was conducted, in which 104 patients of low grade SIL (LSIL), 131 high grade SIL (HSIL) and 176 SCC as well as age‐matched, 1:1 controls were tested for Fas polymorphism by PCR‐RFLP. HPV genotypes were determined in case groups by MY PCR‐reverse line blot. The frequency of A allele was significantly (p = 0.006) higher in SCC than in control, conferring an odd ratio of 1.5 (95% CI = 1.1–2.0). The distribution of Fas (−670) genotypes also differed significantly between HSIL, SCC and each of their control (p = 0.017 and 0.03, respectively), with the A/A genotype conferring an OR of 1.3 (95% CI = 1.1–1.6) and 1.6 (95% CI = 1.0–2.5), respectively. Remarkably, the frequency of A allele and A/A genotype increased gradually in accordance with the multi‐step carcinogenesis from LSIL, HSIL to SCC (ptest for trend = 0.0066 and 0.0007, respectively). In addition, there was no difference of Fas genotypes between HPV (+) and HPV (−) cases. Fas genotypes, however, differed in LSIL infected with different HPV types (p = 0.033). The present study demonstrated an association between Fas polymorphism and cervical carcinogenesis. We deduced a possible effect of apoptosis of immune cells in this virus‐induced cancer.

An epigenetic marker panel for screening and prognostic prediction of ovarian cancer.

Aberrant CpG island hypermethylation is a common finding of cancers, which might be detectable in the tissue or serum of affected patients. We analyzed DNA methylation by methylation‐specific polymerase chain reaction of 7 genes, which included secreted frizzled receptor proteins 1, 2, 4, 5 (SFRP1, 2, 4, 5), SRY‐box 1 (SOX1), paired box gene 1 (PAX1) and LIM homeobox transcription factor 1, alpha (LMX1A) in primary tumor samples from 126 patients with ovarian cancer, 75 with a benign tumor and 14 with borderline malignancy of an ovarian tumor, and in the serum from 26 patients with ovarian cancer and 20 with a benign tumor. Six of 7 genes had higher methylation rates in patients with ovarian cancer than in borderline malignancy or benign tumor (p < 0.001). The methylation of SFRP1, SFRP2, SOX1 and LMX1A genes correlated with recurrence and overall survival of ovarian cancer patients. Combining the data for SFRP1, SFRP2 and SOX1 genes gave a relative risk for recurrence of 3.19 (p = 0.013) in patients with at least one gene methylation, and combining the data for SFRP1, SOX1 and LMX1A gave an RR for cancer‐related death of 6.09 (p = 0.010). Methylation analysis of tissues and serum revealed a significant correlation (kappa values, 0.332–0.598) and a highly sensitivity and specificity rates (73.08 and 75%) as a screening marker. In conclusion, promoter hypermethylation of specific genes in critical pathways is common in ovarian cancer and has potential as a prognostic factor and a promising serum marker for early screening.

Favorable clinical outcome of cervical cancers infected with human papilloma virus type 58 and related types

To determine whether the status of human‐papillomavirus (HPV) infection affects the clinical outcome of cervical carcinoma (CC), HPV genotype was prospectively determined in 94 consecutive CC cases subsequently followed for a median duration of 37.5 months. With a consensus PCR‐RFLP method of HPV genotyping, 81 (86.2%) cancers were positive for HPV DNA. They were classified, according to the phylogenic similarities, into HPV‐16‐related (type 16, nu2009=u200945; type 31, nu2009=u20092), HPV‐58‐related (type 58, nu2009=u200917; type 33, nu2009=u20093; type 52, nu2009=u20092) and HPV‐18‐related (type 18, nu2009=u20098; type 68, nu2009=u20091) groups, and analyzed in relation to clinical outcome. The following results were observed: (i) Type‐58‐related HPVs were more prevalent in the old age (older than the median age of 52) group than in the young age group (41% vs. 14.6%, pu2009=u20090.045); (ii) 63% (5/8) of patients with advanced stages (III and IV) were HPV‐negative, a figure much higher than that (9.3%, 8/84) of patients with early stages (stage I and II) (pu2009=u20090.002); (iii) the occurrence of adenocarcinoma or adenosquamous carcinoma was higher in the HPV‐18‐related group (50%) than in the HPV‐16‐related (33.3%) or the HPV‐58‐related (16.7%) groups (pu2009=u20090.024); (iv) the status of lymph‐node metastasis and tumor grade did not correlate with HPV status; (v) 5‐year survival rates were 90.2%, 80% and 74% for HPV‐58‐, HPV‐16‐ and HPV‐18‐related groups, respectively (pu2009=u20090.03, after adjustment for tumor stage); (vi) in comparison with the HPV‐16‐related group, the relative risk of death in the HPV‐58‐ and the HPV‐18‐related groups were 0.32 [95% CI, 0.07–1.49] and 1.87 [0.36–14.9] respectively. HPV genotype appears to affect the clinical behavior and outcome of cervical cancer. HPV‐58‐related types are prevalent in the older population, and appear to confer a favorable prognosis. Int. J. Cancer (Pred. Oncol.) 84:553–557, 1999.

Growth Inhibition of Ovarian Tumor–Initiating Cells by Niclosamide

A recent hypothesis for cancer chemoresistance posits that cytotoxic survival of a subpopulation of tumor progenitors drives the propagation of recurrent disease, underscoring the need for new therapeutics that target such primitive cells. To discover such novel compounds active against drug-resistant ovarian cancer, we identified a subset of chemoresistant ovarian tumor cells fulfilling current definitions of cancer-initiating cells from cell lines and patient tumors using multiple stemness phenotypes, including the expression of stem cell markers, membrane dye efflux, sphere formation, potent tumorigenicity, and serial tumor propagation. We then subjected such stem-like ovarian tumor-initiating cells (OTIC) to high-throughput drug screening using more than 1,200 clinically approved drugs. Of 61 potential compounds preliminarily identified, more stringent assessments showed that the antihelmintic niclosamide selectively targets OTICs in vitro and in vivo. Gene expression arrays following OTIC treatment revealed niclosamide to disrupt multiple metabolic pathways affecting biogenetics, biogenesis, and redox regulation. These studies support niclosamide as a promising therapy for ovarian cancer and warrant further preclinical and clinical evaluation of this safe, clinically proven drug for the management of this devastating gynecologic malignancy. Mol Cancer Ther; 11(8); 1703–12. ©2012 AACR.

Quantitative DNA methylation analysis detects cervical intraepithelial neoplasms type 3 and worse

DNA methylation may be used a potential biomarker for detecting cervical cancer. The authors of this report used quantitative methylation analysis of 4 genes in a full spectrum of cervical lesions to test its potential clinical application.

Drug Screening Identifies Niclosamide as an Inhibitor of Breast Cancer Stem-Like Cells

The primary cause of death from breast cancer is the progressive growth of tumors and resistance to conventional therapies. It is currently believed that recurrent cancer is repopulated according to a recently proposed cancer stem cell hypothesis. New therapeutic strategies that specifically target cancer stem-like cells may represent a new avenue of cancer therapy. We aimed to discover novel compounds that target breast cancer stem-like cells. We used a dye-exclusion method to isolate side population (SP) cancer cells and, subsequently, subjected these SP cells to a sphere formation assay to generate SP spheres (SPS) from breast cancer cell lines. Surface markers, stemness genes, and tumorigenicity were used to test stem properties. We performed a high-throughput drug screening using these SPS. The effects of candidate compounds were assessed in vitro and in vivo. We successfully generated breast cancer SPS with stem-like properties. These SPS were enriched for CD44high (2.8-fold) and CD24low (4-fold) cells. OCT4 and ABCG2 were overexpressed in SPS. Moreover, SPS grew tumors at a density of 103, whereas an equivalent number of parental cells did not initiate tumor formation. A clinically approved drug, niclosamide, was identified from the LOPAC chemical library of 1,258 compounds. Niclosamide downregulated stem pathways, inhibited the formation of spheroids, and induced apoptosis in breast cancer SPS. Animal studies also confirmed this therapeutic effect. The results of this proof-of-principle study may facilitate the development of new breast cancer therapies in the near future. The extension of niclosamide clinical trials is warranted.

A long-term follow-up study of 176 cases with adult-type ovarian granulosa cell tumors

OBJECTIVEnBecause of rarity, indolent clinical course, and of most importance, small sample size studies of previous ovarian granulosa cell tumors (GCTs), this study was conducted to report the clinical characteristics and long-term outcomes of 176 pathologically confirmed GCTs.nnnMETHODSnBetween 1984 and 2010, we retrospectively evaluated 176 patients from multiple medical centers in Taiwan.nnnRESULTSnThe mean age at the diagnosis was 46 years and nearly half of the patients (45.7%) were in their fourth or fifth decades of life. The most common symptoms included abdominal pain (28.5%), followed by irregular menstruation (16.7%). The mean tumor size was 10.4 cm. The stage distribution at diagnosis was stage I in 77.8% of patients, stage II in 5.1%, stages III-V in 6.1%, and unknown in 11% of patients. The median follow-up period was 60.7 months. The recurrence rate was 21%. The overall 5- and 10-year survival rates were 96.5% and 94.1%, respectively. In univariate analysis, initial stage, presence of residual tumor after initial surgery, need for adjuvant chemotherapy, and tumor size were associated with disease recurrence. In the multivariate analysis, only the presence of residual tumor after initial surgery and tumor size were significantly associated with recurrence.nnnCONCLUSIONSnThe outcomes of patients with GCTs were good, with nearly to 95% of patients surviving 5 and 10 years. The prognosis was related to initial stage, presence of residual tumor after initial surgery, and tumor size (>13.5 cm). Different surgical methods and/or adjuvant therapy appear not to affect the outcome.