[Show abstract][Hide abstract] ABSTRACT: Over three decades have passed since the first report on the expression of CA125 by ovarian tumors. Since that time our understanding of ovarian cancer biology has changed significantly to the point that these tumors are now classified based on molecular phenotype and not purely on histological attributes. However, CA125 continues to be, with the recent exception of HE4, the only clinically reliable diagnostic marker for ovarian cancer. Many large-scale clinical trials have been conducted or are underway to determine potential use of serum CA125 levels as a screening modality or to distinguish between benign and malignant pelvic masses. CA125 is a peptide epitope of a 3-5 million Da mucin, MUC16. Here we provide an in-depth review of the literature to highlight the importance of CA125 as a prognostic and diagnostic marker for ovarian cancer. We focus on the increasing body of literature describing the biological role of MUC16 in the progression and metastasis of ovarian tumors. Finally, we consider previous and on-going efforts to develop therapeutic approaches to eradicate ovarian tumors by targeting MUC16. Even though CA125 is a crucial marker for ovarian cancer, the exact structural definition of this antigen continues to be elusive. The importance of MUC16/CA125 in the diagnosis, progression and therapy of ovarian cancer warrants the need for in-depth research on the biochemistry and biology of this mucin. A renewed focus on MUC16 is likely to culminate in novel and more efficient strategies for the detection and treatment of ovarian cancer.
[Show abstract][Hide abstract] ABSTRACT: Paclitaxel is a mainstay of treatment for many solid tumors, and frequently, clinical outcome is influenced by paclitaxel sensitivity. Despite this, our understanding of the molecular basis of paclitaxel response is incomplete. Recently, it has been shown that microRNAs (miRNAs) influence messenger RNA (mRNA) transcriptional control and can contribute to human carcinogenesis. In the present study, our objective was to identify miRNAs associated with cancer cell line response to paclitaxel and to evaluate these miRNAs as therapeutic targets to increase paclitaxel sensitivity. We measured the expression of 335 unique miRNAs in 40 human cancer cell lines selected from the NCI panel. We then integrated miRNA expression data with publicly available paclitaxel-sensitivity (GI50) data for each of the 40 cell lines to identify miRNAs associated with paclitaxel sensitivity. Ovarian cancer cell lines with differential miRNA expression and paclitaxel sensitivity were transiently transfected with miRNA precursors and inhibitors, and the effects on in vitro cell paclitaxel sensitivity were evaluated. Pearson's correlation identified 2 miRNAs (miR-367 and miR-30a-5p) associated with the NCI40 cell line in vitro paclitaxel response (P<0.0003). Ovarian cancer cells were selected based on the association between paclitaxel sensitivity and miR-367/miR-30a-5p expression. Overexpression of miR-367 in the paclitaxel-sensitive cells [PA1; IC50, 1.69 nM, high miR-367 (2.997), low miR-30a-5p (-0.323)] further increased paclitaxel sensitivity, whereas miR-367 depletion decreased paclitaxel sensitivity. In contrast, overexpression and depletion of miR-30a-5p in the paclitaxel-resistant cells [OVCAR4; IC50, 17.8 nM, low miR-367 (-0.640), high miR-30a-5p (3.270)] decreased and increased paclitaxel sensitivity, respectively. We identified and successfully targeted miRNAs associated with human cancer cell line response to paclitaxel. Our strategy of integrating in vitro miRNA expression and drug sensitivity data may not only aid in the characterization of determinants of drug response but also in the identification of novel therapeutic targets to increase activity of existing therapeutics.
[Show abstract][Hide abstract] ABSTRACT: To evaluate the biologic validity of ovarian cancer (OVCA) screening and early detection efforts and to characterize signaling pathways associated with human cancer metastasis and patient survival.
Using genome-wide expression profiling and DNA sequencing, we compared pelvic and matched extra-pelvic implants from 30 patients with advanced-stage OVCA for expression of molecular signaling pathways and p53 gene mutations. Differentially expressed pathways were further evaluated in a series of primary or early-stage versus metastatic or recurrent cancer samples from 389 ovarian, prostate, and oral cancer patients. Metastasis pathways were also evaluated for associations with survival in nine independent clinico-genomic datasets from 1,691 ovarian, breast, colon, brain, and lung cancer and leukemia patients. The inhibitory effects of one pathway (TGF-WNT) on in-vitro OVCA cell migration were studied.
Pelvic and extra-pelvic OVCA implants demonstrated similar patterns of signaling pathway expression and identical p53 mutations. However, we identified 3 molecular pathways/cellular processes that were differentially expressed between pelvic and extra-pelvic OVCA samples and between primary/early-stage and metastatic/advanced or recurrent ovarian, oral, and prostate cancers. Furthermore, their expression was associated with overall survival from ovarian cancer (P=0.006), colon cancer (1 pathway at P=0.005), and leukemia (P=0.05). Artesunate-induced TGF-WNT pathway inhibition impaired OVCA cell migration.
Advanced-stage OVCA has a unifocal origin in the pelvis. Molecular pathways associated with extra-pelvic OVCA spread are also associated with metastasis from other human cancers and with overall patient survival. Such pathways represent appealing therapeutic targets for patients with metastatic disease.
American journal of obstetrics and gynecology 08/2013; · 3.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: The efficacy and safety of bevacizumab and docetaxel were evaluated in women who developed recurrent epithelial ovarian, fallopian, or peritoneal cancer within 12months of platinum-based therapy. METHODS: Patients received docetaxel (40mg/m(2)) on days 1 and 8 and bevacizumab (15mg/kg) on day 1 of a 21-daycycle. Primary endpoint was 6-month progression-free survival (PFS). RESULTS: Forty-one patients were evaluable for PFS and 38 for best response; 46% had platinum-free intervals (PFI) of <6months and 54% between 6 and 12months. The 6-month PFS was 43.9% (95% confidence interval (CI95%)=28.6-58.2%). Median PFS (months) was 5.2 (CI95%=4.4-7.2) for all patients, 6.2 (CI95%=4.1-7.4) for patients with PFI <6months, and 5.1 (CI95%=3.0-7.2) for those with PFI ≥6months. Twenty-two patients showed overall response (CR+PR) (57.9%; CI95%=40.8-73.7%), and 32 showed clinical benefit (CR+PR+SD) (84.2%; CI95%=68.8-94.0%). For those with complete or partial responses, median duration of response was 4.8months (0.7-14.5). Median overall survival was 12.4months (CI95%=10.0-21.9). The most common grade 3/4 adverse events (AEs) were neutropenia (14.6% of patients), followed by leukopenia, fatigue, metabolic, and gastrointestinal, with 66% showing any grade 3/4 toxicity. Most common AEs of any grade were gastrointestinal (93%), fatigue (73%), and pain (73%). Four (10%) patients developed hypertension, 1 a gastrointestinal perforation, and another a colovesicular fistula. CONCLUSIONS: Bevacizumab and docetaxel administered in patients with recurrent ovarian cancer is an active regimen without new unanticipated toxicities. This combination should be an option for further study or clinical use in recurrent ovarian cancer.
[Show abstract][Hide abstract] ABSTRACT: Epithelial ovarian cancer (EOC) has a heritable component that remains to be fully characterized. Most identified common susceptibility variants lie in non-protein-coding sequences. We hypothesized that variants in the 3' untranslated region at putative microRNA (miRNA)-binding sites represent functional targets that influence EOC susceptibility. Here, we evaluate the association between 767 miRNA-related single-nucleotide polymorphisms (miRSNPs) and EOC risk in 18,174 EOC cases and 26,134 controls from 43 studies genotyped through the Collaborative Oncological Gene-environment Study. We identify several miRSNPs associated with invasive serous EOC risk (odds ratio=1.12, P=10(-8)) mapping to an inversion polymorphism at 17q21.31. Additional genotyping of non-miRSNPs at 17q21.31 reveals stronger signals outside the inversion (P=10(-10)). Variation at 17q21.31 is associated with neurological diseases, and our collaboration is the first to report an association with EOC susceptibility. An integrated molecular analysis in this region provides evidence for ARHGAP27 and PLEKHM1 as candidate EOC susceptibility genes.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: To evaluate the toxicity and tolerability of the Intraperitoneal/Intravenous (IP/IV) regimen utilized at Moffitt Cancer Center and to compare our findings with the IP, Gynecologic Oncology Group (GOG) study 172. STUDY DESIGN: Using the Moffitt database, we evaluated the outcomes of patients who underwent primary optimal cytoreduction for stage IIC-IV, epithelial ovarian, tubal, and peritoneal carcinoma followed by the intent to treat with IP/IV chemotherapy. NCI CTCAE v3.0 was used to grade adverse events. RESULTS: We identified 69 patients meeting our inclusion criteria from 2006 - 2011. The most frequent grade 3/4 toxicities were neutropenia (48%), gastrointestinal (9%), metabolic (9%), and infection (5%). Remaining toxicities occurred in < 5% of patients. Patients received a greater number of cycles compared to GOG 172 (4.28 vs. 3.66, respectively, p = 0.0088). CONCLUSION: Through the use of supportive care and the preemptive management of established sideeffects, the associated toxicities and tolerability of IP chemotherapy appear improved.
American journal of obstetrics and gynecology 03/2013; · 3.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Elevated serum levels of hepatocyte growth factor (HGF) and high tumor expression of c-Met are both indicators of poor overall survival from ovarian cancer (OVCA). In the present study, we evaluated the role of the HGF signaling pathway in OVCA cell line chemoresistance and OVCA patient overall survival as well as the influence of HGF/c-Met signaling inhibition on the sensitivity of OVCA cells to combinational carboplatin plus paclitaxel therapy. The prevalence of the HGF receptor, c-Met, was determined by immunohistochemistry in primary OVCA samples (n=79) and OVCA cell lines (n=41). The influence of the c-Met-specific inhibitor MK8033 on OVCA cell sensitivity to combinations of carboplatin plus paclitaxel was examined in a subset of OVCA cells (n=8) by CellTiter-Blue cell viability assays. Correlation tests were used to identify genes associated with response to MK8033 and carboplatin plus paclitaxel. Identified genes were evaluated for influence on overall survival from OVCA using principal component analysis (PCA) modeling in an independent clinical OVCA dataset (n=218). Immunohistochemistry analysis indicated that 83% of OVCA cells and 92% of primary OVCA expressed the HGF receptor, c-Met. MK8033 exhibited significant anti-proliferative effects against a panel of human OVCA cell lines. Combination index values determined by the Chou-Talalay isobologram equation indicated synergistic activity in combinations of MK8033 and carboplatin plus paclitaxel. Pearson's correlation identified a 47-gene signature to be associated with MK8033-carboplatin plus paclitaxel response. PCA modeling indicated an association of this 47-gene response signature with overall survival from OVCA (P=0.013). These data indicate that HGF/c-Met pathway signaling may influence OVCA chemosensitivity and overall patient survival. Furthermore, HGF/c-Met inhibition by MK8033 represents a promising new therapeutic avenue to increase OVCA sensitivity to carboplatin plus paclitaxel.
[Show abstract][Hide abstract] ABSTRACT: Most women with advanced-stage epithelial ovarian cancer (OVCA) ultimately develop chemoresistant recurrent disease. Therefore, a great need to develop new, more active, and less toxic agents and/or to optimize the efficacy of existing agents exists.
In this study, we investigated the activity of Avemar, a natural, nontoxic, fermented wheat germ extract (FWGE), against a range of OVCA cell lines, both alone and in combination with cisplatin chemotherapy and delineated the molecular signaling pathways that underlie FWGE activity at a genome-wide level.
We found that FWGE exhibited significant antiproliferative effects against 12 human OVCA cell lines and potentiated cisplatin-induced apoptosis. Pearson correlation of FWGE sensitivity and gene expression data identified 2142 genes (false discovery rate < 0.2) representing 27 biologic pathways (P < 0.05) to be significantly associated with FWGE sensitivity. A parallel analysis of genomic data for 59 human cancer cell lines matched to chemosensitivity data for 2,6-dimethoxy-p-benzoquinone, a proposed active component of FWGE, identified representation of 13 pathways common to both FWGE and 2,6-dimethoxy-p-benzoquinone sensitivity.
Our findings confirm the value of FWGE as a natural product with anticancer properties that may also enhance the activity of existing therapeutic agents. Furthermore, our findings provide substantial insights into the molecular basis of FWGE's effect on human cancer cells. RESEARCH HIGHLIGHTS:
International Journal of Gynecological Cancer 07/2012; 22(6):960-7. · 1.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Carboplatin and cisplatin, alone or in combination with paclitaxel, have similar efficacies against ovarian cancer (OVCA) yet exhibit different toxicity profiles. We characterised the common and unique cellular pathways that underlie OVCA response to these drugs and analyse whether they have a role in OVCA survival.
Ovarian cancer cell lines (n=36) were treated with carboplatin, cisplatin, paclitaxel, or carboplatin-paclitaxel (CPTX). For each cell line, IC(50) levels were quantified and pre-treatment gene expression analyses were performed. Genes demonstrating expression/IC(50) correlations (measured by Pearson; P<0.01) were subjected to biological pathway analysis. An independent OVCA clinico-genomic data set (n=142) was evaluated for clinical features associated with represented pathways.
Cell line sensitivity to carboplatin, cisplatin, paclitaxel, and CPTX was associated with the expression of 77, 68, 64, and 25 biological pathways (P<0.01), respectively. We found three common pathways when drug combinations were compared. Expression of one pathway ('Transcription/CREB pathway') was associated with OVCA overall survival.
The identification of the Transcription/CREB pathway (associated with OVCA cell line platinum sensitivity and overall survival) could improve patient stratification for treatment with current therapies and the rational selection of future OVCA therapy agents targeted to these pathways.
British Journal of Cancer 05/2012; 106(12):1967-75. · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ovarian cancer (OVCA) is the most lethal gynecological malignancy. The high mortality rate associated with this disease is due in large part to the development of resistance to chemotherapy; however, the biological basis of this remains unclear. Gemcitabine is frequently used for the treatment of patients with platinum-resistant OVCA. We report molecular signaling pathways associated with OVCA response to gemcitabine. Forty-one OVCA cell lines were subjected to gene expression analysis; in parallel, IC50 values for gemcitabine were quantified using CellTiter-Blue viability assays. Pearson's correlation coefficients were calculated for gene expression and gemcitabine IC50 values. The genes associated with gemcitabine sensitivity were subjected to pathway analysis. For the identified pathways, principal component analysis was used to derive pathway signatures and corresponding scores, which represent overall measures of pathway expression. Expression levels of the identified pathways were then evaluated in a series of clinico-genomic datasets from 142 patients with stage III/IV serous OVCA. We found that in vitro gemcitabine sensitivity was associated with expression of 131 genes (p<0.001). These genes include significant representation of three molecular signaling pathways (p<0.02): O-glycan biosynthesis, Role of Nek in cell cycle regulation and Antiviral actions of Interferons. In an external clinico-genomic OVCA dataset (n=142), expression of the O-glycan pathway was associated with overall survival, independent of surgical cytoreductive status, grade and age (p<0.001). Expression levels of Role of Nek in cell cycle regulation and Antiviral actions of Interferons were not associated with survival (p=0.31 and p=0.54, respectively). Collectively, expression of the O-glycan biosynthesis pathway, which modifies protein function via post-translational carbohydrate binding, is independently associated with overall survival from OVCA. Our findings shed light on the molecular basis of OVCA responsiveness to gemcitabine and also identify a signaling pathway that may influence patient survival.
International Journal of Oncology 04/2012; 41(1):179-88. · 2.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To identify pathways that influence endometrial cancer (EC) cell sensitivity to cisplatin and to characterize the BCL2 antagonist of cell death (BAD) pathway as a therapeutic target to increase cisplatin sensitivity.
Eight EC cell lines (Ishikawa, MFE296, RL 95-2, AN3CA, KLE, MFE280, MFE319, HEC-1-A) were subjected to Affymetrix Human U133A GeneChip expression analysis of approximately 22,000 probe sets. In parallel, endometrial cell line sensitivity to cisplatin was quantified by MTS assay, and IC(50) values were calculated. Pearson's correlation test was used to identify genes associated with response to cisplatin. Genes associated with cisplatin responsiveness were subjected to pathway analysis. The BAD pathway was identified and subjected to targeted modulation, and the effect on cisplatin sensitivity was evaluated.
Pearson's correlation analysis identified 1443 genes associated with cisplatin resistance (P<0.05), which included representation of the BAD-apoptosis pathway. Small interfering RNA (siRNA) knockdown of BAD pathway protein phosphatase PP2C expression was associated with increased phosphorylated BAD (serine-155) levels and a parallel increase in cisplatin resistance in Ishikawa (P=0.004) and HEC-1-A (P=0.02) cell lines. In contrast, siRNA knockdown of protein kinase A expression increased cisplatin sensitivity in the Ishikawa (P=0.02) cell line.
The BAD pathway influences EC cell sensitivity to cisplatin, likely via modulation of the phosphorylation status of the BAD protein. The BAD pathway represents an appealing therapeutic target to increase EC cell sensitivity to cisplatin.
[Show abstract][Hide abstract] ABSTRACT: The BCL2 family proteins are critical mediators of cellular apoptosis and, as such, have been implicated as determinants of cancer cell chemo-sensitivity. Recently, it has been demonstrated that the phosphorylation status of the BCL2 antagonist of cell death (BAD) protein may influence ovarian cancer (OVCA) cell sensitivity to cisplatin. Here, we sought to evaluate how kinase and phosphatase components of the BAD apoptosis pathway influence OVCA chemo-sensitivity.
Protein levels of cyclin-dependent kinase 1 (CDK1) and protein phosphatase 2C (PP2C) were measured by immunofluorescence in a series of 64 primary advanced-stage serous OVCA patient samples. In parallel, levels of cAMP-dependent protein kinase (PKA), AKT, and PP2C were quantified by Western blot analysis in paired mother/daughter platinum-sensitive/resistant OVCA cell lines (A2008/C13, A2780S/A2780CP, Chi/ChiR). BAD pathway kinase CDK1 was depleted using siRNA transfection, and the influence on BAD phosphorylation and cisplatin-induced apoptosis was evaluated.
OVCA patient samples that demonstrated complete responses to primary platinum-based therapy demonstrated 4-fold higher CDK1 (p<0.0001) and 2-fold lower PP2C (p=0.14) protein levels than samples that demonstrated incomplete responses. Protein levels of PP2C were lower in the platinum-resistant versus that shown in the platinum-sensitive OVCA cell line sub-clones. Levels of PKA were higher in all platinum-resistant than in platinum-sensitive OVCA cell line sub-clones. Selective siRNA depletion of CDK1 increased sensitivity to cisplatin-induced apoptosis (p<0.002).
BAD pathway kinases and phosphatases, including CDK1 and PP2C, are associated with OVCA sensitivity to platinum and may represent therapeutic opportunities to enhance cytotoxic efficacy.
Journal of Gynecologic Oncology 01/2012; 23(1):35-42. · 1.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the National Cancer Institute Cancer Genetic Markers of Susceptibility (CGEMS) genome-wide association study of breast cancer, a single nucleotide polymorphism (SNP) marker, rs999737, in the 14q24.1 interval, was associated with breast cancer risk. In order to fine map this region, we imputed a 3.93 MB region flanking rs999737 for Stages 1 and 2 of the CGEMS study (5,692 cases, 5,576 controls) using the combined reference panels of the HapMap 3 and the 1000 Genomes Project. Single-marker association testing and variable-sized sliding-window haplotype analysis were performed, and for both analyses the initial tagging SNP rs999737 retained the strongest association with breast cancer risk. Investigation of contiguous regions did not reveal evidence for an additional independent signal. Therefore, we conclude that rs999737 is an optimal tag SNP for common variants in the 14q24.1 region and thus narrow the candidate variants that should be investigated in follow-up laboratory evaluation.
Human Genetics 09/2011; 131(3):479-90. · 4.63 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Despite initial sensitivity to chemotherapy, ovarian cancers (OVCA) often develop drug resistance, which limits patient survival. Using specimens and/or genomic data from 289 patients and a panel of cancer cell lines, we explored genome-wide expression changes that underlie the evolution of OVCA chemoresistance and characterized the BCL2 antagonist of cell death (BAD) apoptosis pathway as a determinant of chemosensitivity and patient survival.
Serial OVCA cell cisplatin treatments were performed in parallel with measurements of genome-wide expression changes. Pathway analysis was carried out on genes associated with increasing cisplatin resistance (EC(50)). BAD-pathway expression and BAD protein phosphorylation were evaluated in patient samples and cell lines as determinants of chemosensitivity and/or clinical outcome and as therapeutic targets.
Induced in vitro OVCA cisplatin resistance was associated with BAD-pathway expression (P < 0.001). In OVCA cell lines and primary specimens, BAD protein phosphorylation was associated with platinum resistance (n = 147, P < 0.0001) and also with overall patient survival (n = 134, P = 0.0007). Targeted modulation of BAD-phosphorylation levels influenced cisplatin sensitivity. A 47-gene BAD-pathway score was associated with in vitro phosphorylated BAD levels and with survival in 142 patients with advanced-stage (III/IV) serous OVCA. Integration of BAD-phosphorylation or BAD-pathway score with OVCA surgical cytoreductive status was significantly associated with overall survival by log-rank test (P = 0.004 and P < 0.0001, respectively).
The BAD apoptosis pathway influences OVCA chemosensitivity and overall survival, likely via modulation of BAD phosphorylation. The pathway has clinical relevance as a biomarker of therapeutic response, patient survival, and as a promising therapeutic target.
Clinical Cancer Research 08/2011; 17(19):6356-66. · 7.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Genome-wide association studies have identified prostate cancer susceptibility alleles on chromosome 11q13. As part of the Cancer Genetic Markers of Susceptibility (CGEMS) Initiative, the region flanking the most significant marker, rs10896449, was fine mapped in 10 272 cases and 9123 controls of European origin (10 studies) using 120 common single nucleotide polymorphisms (SNPs) selected by a two-staged tagging strategy using HapMap SNPs. Single-locus analysis identified 18 SNPs below genome-wide significance (P< 10(-8)) with rs10896449 the most significant (P= 7.94 × 10(-19)). Multi-locus models that included significant SNPs sequentially identified a second association at rs12793759 [odds ratio (OR) = 1.14, P= 4.76 × 10(-5), adjusted P= 0.004] that is independent of rs10896449 and remained significant after adjustment for multiple testing within the region. rs10896438, a proxy of previously reported rs12418451 (r(2)= 0.96), independent of both rs10896449 and rs12793759 was detected (OR = 1.07, P= 5.92 × 10(-3), adjusted P= 0.054). Our observation of a recombination hotspot that separates rs10896438 from rs10896449 and rs12793759, and low linkage disequilibrium (rs10896449-rs12793759, r(2)= 0.17; rs10896449-rs10896438, r(2)= 0.10; rs12793759-rs10896438, r(2)= 0.12) corroborate our finding of three independent signals. By analysis of tagged SNPs across ∼123 kb using next generation sequencing of 63 controls of European origin, 1000 Genome and HapMap data, we observed multiple surrogates for the three independent signals marked by rs10896449 (n= 31), rs10896438 (n= 24) and rs12793759 (n= 8). Our results indicate that a complex architecture underlying the common variants contributing to prostate cancer risk at 11q13. We estimate that at least 63 common variants should be considered in future studies designed to investigate the biological basis of the multiple association signals.
Human Molecular Genetics 07/2011; 20(14):2869-78. · 7.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Single nucleotide polymorphisms (SNP) in microRNA-related genes have been associated with epithelial ovarian cancer (EOC) risk in two reports, yet associated alleles may be inconsistent across studies.
We conducted a pooled analysis of previously identified SNPs by combining genotype data from 3,973 invasive EOC cases and 3,276 controls from the Ovarian Cancer Association Consortium. We also conducted imputation to obtain dense coverage of genes and comparable genotype data for all studies. In total, 226 SNPs within 15 kb of 4 miRNA biogenesis genes (DDX20, DROSHA, GEMIN4, and XPO5) and 23 SNPs located within putative miRNA binding sites of 6 genes (CAV1, COL18A1, E2F2, IL1R1, KRAS, and UGT2A3) were genotyped or imputed and analyzed in the entire dataset.
After adjustment for European ancestry, no overall association was observed between any of the analyzed SNPs and EOC risk.
Common variants in these evaluated genes do not seem to be strongly associated with EOC risk.
This analysis suggests earlier associations between EOC risk and SNPs in these genes may have been chance findings, possibly confounded by population admixture. To more adequately evaluate the relationship between genetic variants and cancer risk, large sample sizes are needed, adjustment for population stratification should be carried out, and use of imputed SNP data should be considered.
[Show abstract][Hide abstract] ABSTRACT: Defective microRNA (miRNA) biogenesis contributes to the development and progression of epithelial ovarian cancer (EOC). In this study, we examined the hypothesis that single nucleotide polymorphisms (SNP) in miRNA biogenesis genes may influence EOC risk. In an initial investigation, 318 SNPs in 18 genes were evaluated among 1,815 EOC cases and 1,900 controls, followed up by a replicative joint meta-analysis of data from an additional 2,172 cases and 3,052 controls. Of 23 SNPs from 9 genes associated with risk (empirical P < 0.05) in the initial investigation, the meta-analysis replicated 6 SNPs from the DROSHA, FMR1, LIN28, and LIN28B genes, including rs12194974 (G>A), an SNP in a putative transcription factor binding site in the LIN28B promoter region (summary OR = 0.90, 95% CI: 0.82-0.98; P = 0.015) which has been recently implicated in age of menarche and other phenotypes. Consistent with reports that LIN28B overexpression in EOC contributes to tumorigenesis by repressing tumor suppressor let-7 expression, we provide data from luciferase reporter assays and quantitative RT-PCR to suggest that the inverse association among rs12194974 A allele carriers may be because of reduced LIN28B expression. Our findings suggest that variants in LIN28B and possibly other miRNA biogenesis genes may influence EOC susceptibility.
Cancer Research 06/2011; 71(11):3896-903. · 9.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Identification of somatic mutations in cancer is a major goal for understanding and monitoring the events related to cancer initiation and progression. High resolution melting (HRM) curve analysis represents a fast, post-PCR high-throughput method for scanning somatic sequence alterations in target genes. The aim of this study was to assess the sensitivity and specificity of HRM analysis for tumor mutation screening in a range of tumor samples, which included 216 frozen pediatric small rounded blue-cell tumors as well as 180 paraffin-embedded tumors from breast, endometrial and ovarian cancers (60 of each). HRM analysis was performed in exons of the following candidate genes known to harbor established commonly observed mutations: PIK3CA, ERBB2, KRAS, TP53, EGFR, BRAF, GATA3, and FGFR3. Bi-directional sequencing analysis was used to determine the accuracy of the HRM analysis. For the 39 mutations observed in frozen samples, the sensitivity and specificity of HRM analysis were 97% and 87%, respectively. There were 67 mutation/variants in the paraffin-embedded samples, and the sensitivity and specificity for the HRM analysis were 88% and 80%, respectively. Paraffin-embedded samples require higher quantity of purified DNA for high performance. In summary, HRM analysis is a promising moderate-throughput screening test for mutations among known candidate genomic regions. Although the overall accuracy appears to be better in frozen specimens, somatic alterations were detected in DNA extracted from paraffin-embedded samples.
PLoS ONE 01/2011; 6(1):e14522. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Genome-wide association studies (GWAS) have emerged as an important tool for discovering regions of the genome that harbor genetic variants that confer risk for different types of cancers. The success of GWAS in the last 3 years is due to the convergence of new technologies that can genotype hundreds of thousands of single-nucleotide polymorphism markers together with comprehensive annotation of genetic variation. This approach has provided the opportunity to scan across the genome in a sufficiently large set of cases and controls without a set of prior hypotheses in search of susceptibility alleles with low effect sizes. Generally, the susceptibility alleles discovered thus far are common, namely, with a frequency in one or more population of >10% and each allele confers a small contribution to the overall risk for the disease. For nearly all regions conclusively identified by GWAS, the per allele effect sizes estimated are <1.3. Consequently, the findings of GWAS underscore the complex nature of cancer and have focused attention on a subset of the genetic variants that comprise the genomic architecture of each type of cancer, which already can differ substantially by the number of regions associated with specific types of cancer. For instance, in prostate cancer, there could be >30 distinct regions harboring common susceptibility alleles identified by GWAS, whereas in lung cancer, a disease strongly driven by exposure to tobacco products, so far, only three regions have been conclusively established. To date, >85 regions have been conclusively associated in over a dozen different cancers, yet no more than five regions have been associated with more than one distinct cancer type. GWAS are an important discovery tool that require extensive follow-up to map each region, investigate the biological mechanism underpinning the association and eventually test the optimal markers for assessing risk for a disease or its outcome, such as in pharmacogenomics, the study of the effect of genetic variation on pharmacological interventions. The success of GWAS has opened new horizons for exploration and highlighted the complex genomic architecture of disease susceptibility.