- A Novel Technology for Early Detection of Serum LPAs in Ovarian Cancer
- Tipping the Balance: KLF6 Isoforms and Ovarian Cancer
- Novel bioinformatics approach to epithelial ovarian cancer marker identification
- New Molecular Technology to Identify Candidate Ovarian Cancer Oncogenes
- Liposome-Based Radiotherapies for the Treatment of Ovarian Cancer
- Training our Nation's Finest Researchers
While local ovarian cancer has a 5-year relative survival rate greater than 80%, most women are diagnosed with advanced stage disease and a 5-year survival rate of less than 30% because ovarian cancer is often without overt or specific symptoms until late in its development. Thus, detection of ovarian cancer at an early stage has the potential of an immediate and significant impact on this disease. Dr. Gordon Mills of The University of Texas M.D. Anderson Cancer Center previously demonstrated that the ascites and blood of ovarian cancer patients contain high levels of lysophosphatidic acid (LPA), and that LPA contributes to the growth and invasion of the disease and reduces sensitivity to cisplatin. Dr. Mills received a Fiscal Year 2002 Department of Defense Ovarian Cancer Research Program Idea Development Award to combine two novel technologies - surface-enhanced laser desorption and ionization time of flight (SELDI-TOF) mass spectroscopy and development of antibodies to specific phospholipids and lysophospholipids - for quantifying multiple forms of LPA in women at high and low risk for ovarian cancer. Dr. Mills and his team are working to develop a screening tool for the detection of LPAs in ovarian cancer and have combined high-throughput technology with powerful bioinformatics tools to enable detection of ovarian cancer at an early, curable stage. Thus far, this technology has been validated as a rapid and efficient method for the analysis of the more common LPAs in plasma. The team has demonstrated that SELDI-TOF mass spectroscopy has the ability to detect and characterize model lysophospholipids, including lysophosphatidylcholine, sphingosylphosphorylcholine, and lysophosphatidylserine, present in plasma and serum. Dr. Mills's team anticipates further development of these combined technologies into a cost-effective and robust method that could have a strong commercial potential for LPA screening for ovarian cancer. Significantly, in collaboration with LPATH Therapeutics of San Diego, they are assessing whether specific antibodies to lysophospholipids can facilitate the detection of lysophospholipids and their isoforms in blood. These approaches may not only lead to methods for early detection but may yield theragnostics to determine which patients are likely to respond to emerging therapeutics targeting the production and action of lysophospholipids.
Qian L, Xu Y, Simper T, et al. 2006. Phosphorothioate analogues of alkyl lysophosphatidic acid as LPA3 receptor-selective agonists. ChemMedChem 1:376 383.
Tanyi JL, Croetzer D, Wolf J, et al. 2006. Lysophosphatidic acid as a target for molecular diagnosis and therapy of ovarian cancer. In: Functional Lipidomics (Feng L and Prestwich GD, Eds.). CRC Press/Taylor & Francis, New York, New York 101-124.
Visentin B, Vekich JA, Sibbald BJ, et al. 2006. Sphingosine-1-phosphate is required for tumor growth, invasion and angiogenesis mediated by bFGF and VEGF in multiple tumor lineages: Validation of an anti-S1P antibody as a potential therapeutic. Cancer Cell 9:225-238.
Desmaret S, Qian L, Vanloo B, et al. 2005. Lysophosphatidic acid affinity chromatography reveals pyruvate kinase as a specific LPA-binding protein. Biological Chemistry 386(11):1137-1147.
Xu Y, Aoki J, Shimizu K, et al. 2005. Structure activity relationships of fluorinated lysophosphatidic acid analogues: Discovery of high-affinity LPA3 receptor agonists. Journal of Medicinal Chemistry 48:3319-3327.
Umezu-Goto M, Tanyi J, Lahad J, et al. 2004. Lysophosphatidic acid production and action: Validated targets in cancer? Journal of Cellular Biochemistry 92:1115-1140.
Mills GB and Moolenaar WH. 2003. Emerging role of lysophosphatidic acid in cancer. Nature Reviews. Cancer 3:582-591.
Although the five year survival rate for women diagnosed with epithelial ovarian cancer has increased over the past 40 years, the mortality rate has remained constant. Understanding the genetic factors responsible for initiation, progression, and reoccurrence of ovarian cancer may lead to new therapeutic approaches. Dr. John Martignetti received a Fiscal Year 2002 (FY02) Ovarian Cancer Research Program Idea Development Award to investigate the Kruppel-like factor-6 (KLF6) zinc finger transcription factor in ovarian cancer. KLF6 is involved in regulating differentiation, development, cellular proliferation, growth-related signal transduction, and apoptosis, and has been shown to be a tumor suppressor in various human cancers. Dr. Martignetti and colleagues analyzed 68 samples of human ovarian tumors with a range of clinical-pathological profiles and showed that more than 50% have a loss of heterozygosity at the KLF6 locus and associated decreased KLF6 expression. However, overexpression of the KLF6-SV1 splice variant of KLF6 is associated with poorly differentiated higher stage serous tumors. KLF6-SV1 appears to act by interfering with KLF6's normal transcription factor activity controlling cellular growth, adhesion, and motility. Recently, Dr. Martignetti focused on one KLF6 transcriptional target, E-cadherin. He used small interfering RNAs (siRNA) in vitro to target KLF6 isoform expression, and showed that targeted KLF6 reduction results in a 50% reduction of E-cadherin expression, while targeting KLF6-SV1 with siRNA causes a fivefold upregulation of E-cadherin. These changes in E-cadherin levels are accompanied by downstream changes in the subcellular localization of beta-catenin and expression of c-myc. Patient samples from epithelial ovarian tumors with low KLF6 and high KLF6-SV1 expression ratios show significantly decreased E-cadherin expression, confirming the in vitro results. These findings increase our understanding of ovarian cancer progression and metastasis, and also show that targeting KLF6-SV1 to tip the balance in favor of KFL6 could be a succcessful therapy for ovarian cancer.
Difeo A, Narla G, Camacho-Vanegas O, Nishio H, Rose SL, Buller RE, Friedman SL, Walsh MJ, and Martignetti JA.. 2006. E-cadherin is a novel transcriptional target of the KLF6 tumor suppressor. Oncogene (in press).
DiFeo A, Narla G, Hirshfeld J, Camacho-Vanegas O, Narla J, Rose SL, Kalir T, Yao S, Levine A, Birrer MJ, Bonome T, Friedman SL, Buller RE, and Martignetti JA. 2006. Roles of KLF6 and KLF6-SV1 in ovarian cancer progression and intraperitoneal dissemination. Clin Cancer Res 12:3730-3739.
Dr. Igor Jurisica of the Ontario Cancer Institute, Princess Margaret Hospital, is creating computational tools and methods for analysis of complex and diverse biochemical, biological, and clinical data on epithelial ovarian cancer. The investigator's novel bioinformatics approach is an expansion of the Online Predicted Human Interaction Database, a web-based database of predicted and known human protein-protein interactions. With funding from an Ovarian Cancer Research Program Fiscal Year 2004 New Investigator Award, Dr. Jurisica and his team have combined publicly available sources of information on antibodies, proteins, the metabolic pathways from the Kyoto Encyclopedia of Genes and Genomes database, ovarian cancer protein array data, single nucleotide polymorphism (SNP) data, and genomic hybridization databases comparing diverse tumor samples, normal controls, and cell lines. Work thus far has yielded sets of genes differentially expressed between low grade tumors (grade I or II) and normal ovarian surface epithelial cells (OSE), and between high grade tumors (grade III and IV) and OSE, as well as androgen-modulated genes in OSE cells from BRCA mutation carriers. These findings will contribute to prediction of ovarian cancer outcome and survival. In addition, Dr. Jurisica compared gene expression in patients receiving neoadjuvant versus adjuvant chemotherapy and identified more than 50 genes with differential regulation that might be used to identify responders versus non-responders. Dr. Jurisica's team continues to further validate and perform functional studies of these genes. These innovative bioinformatics tools developed by Dr. Jurisica should identify new diagnostic and prognostic markers for epithelial ovarian cancer that could also serve as therapeutic targets for drugs designed to treat epithelial ovarian cancer.
Motamed-Khorasani A, Jurisica I, Letarte M, Shaw PA, Parkes RK, Zhang X, Evangelou A, Rosen B, Murphy KJ, and Brown TJ. 2006. Differentially androgen-modulated genes in ovarian epithelial cells from BRCA mutation carriers and control patients predict ovarian cancer survival and disease progression. Oncogene (in press).
Arshadi N and Jurisica I. 2005. Integrating case-based reasoning systems with data mining techniques for discovering and using disease biomarkers. IEEE Transactions on Knowledge and Data Engineering 17:1127-1137.
Gene expression profiling has been successfully utilized in the past to identify biomarkers and oncogenes related to ovarian cancer. However, pinpointing those genes that are truly active in oncogenesis and not those that are secondarily being altered in expression is problematic. Dr. Tian-Li Wang of Johns Hopkins University Medical School and colleagues have developed a new technology, termed digital karyotyping, that allows investigators to analyze DNA copy number alterations on a genome-wide scale with high resolution. This technique is based upon extracting and counting sequence tags associated with each locus of the genome. Dr. Wang believes that genetic variances that arise from such alterations would be more likely to directly contribute to tumorigenesis, hypothesizing that the use of this technique in conjunction with other techniques that delineate gene expression will significantly facilitate the identification of ovarian tumor oncogenes. With funding from a Department of Defense Ovarian Cancer Research Program Fiscal Year 2004 New Investigator Award, Dr. Wang found amplification at chromosome 11q13.5 in two out of six carcinomas studied and the ovarian cancer cell line OVCAR3. Once these results were verified, the study was expanded and 211 specimens were examined by fluorescent in situ hybridization. The high-grade serous carcinoma samples were 13.2 % positive for the 11q13.5 amplification, whereas none of the lower grade serous carcinomas or control ovaries was positive. Transcriptional analysis of the region revealed overexpression of the Rsf-1 gene, which is known to play a role in chromatin remodeling and transcriptional regulation. A retrospective study revealed that those patients with high-grade serous carcinomas and the Rsf-1 amplification had significantly shorter overall survival compared to those patients without the amplification. Furthermore, the levels of Rsf-1 expression correlated with clinical outcome. Overexpression of Rsf-1 in cultured normal cells resulted in increased cell proliferation and transformation. In addition, knocking down Rsf-1 gene expression in OVCAR3 cells resulted in diminished cell growth. Dr. Wang plans on further exploring this finding and to continue using this technique to identify other potential oncogenes.
Shih I, Sheu J, Santillan A, Nakayama K, Yen M, Bristow R, Vang R, Parmigiani G, Kurman R, Trope C, and Wang T. 2005. Amplification of a chromatin remodeling gene, Rsf-1/HBXAP, in ovarian carcinoma. Proceedings of the National Academy of Sciences 102(39):14004-14009.
I Shih and T Wang. 2005. Apply innovative technologies to explore cancer genome. Current Opinion in Oncology 17:33-38.
Dr. George Sgouros of Johns Hopkins University is developing alpha-particle emitters as radiotherapeutics for advanced ovarian cancer. Because of their high energy deposition, only 1 to 3 alpha-particle traversals through the cell nucleus are required for cell killing. In addition, the short range of alpha-particles allows for minimal normal tissue irradiation. Actinium-225 decays and generates three alpha-particle-emitting daughters, rendering it an attractive candidate for alpha-therapy. Delivery of alpha-emitting radionuclides to micrometastases is challenging. The efficacy of this radiotherapeutic technique is dependent on limiting the escape and distribution of the daughter nuclides throughout the body. The daughter nuclides can not be retained by commonly used antibodies or polymers. With funding from the fiscal year 2002 Ovarian Cancer Research Program, Dr. Sgouros and his team have prepared novel multivesicular liposomes (MUVELs) to retain both the parent radionuclide and its daughter particles. Engineering of the MUVEL structure permits the targeting of SKOV3 human ovarian carcinoma cells by conjugating with Herceptin ® (trastuzumab). This antibody permits specific targeting against ovarian cancer cells. The promising results from the in vitro studies prompted in vivo studies, which revealed that MUVELs may provide an alternative treatment method for metastatic disease. While further studies are required to boost the retention of daughter nuclides and reduce organ toxicity, MUVELs do show great promise as potential vehicles for enhancing alpha-therapy against advanced metastatic ovarian cancer.
Sofou S, Thomas JT, Lin H, McDevitt MR, Scheinberg DA, Sgouros G. 2004. Engineered liposomes for potential alpha-particle therapy of metastatic cancer. Journal of Nuclear Medicine 45:253-260
Dr. Michael Seiden, Chairman of the Research Committee of the Gynecologic Oncology Program at Dana Farber Cancer Institute/Harvard Cancer Center, was the recipient of an FY02 OCRP Institutional Training Grant (ITG). This mechanism was designed to encourage the initiation of a new postgraduate training program in ovarian cancer. The intent of the ITG was to focus on one or more program emphasis area(s) (i.e., etiology, prevention, early detection/diagnosis, and preclinical therapeutics) as related to epithelial ovarian carcinoma and/or primary peritoneal carcinoma. The ITG has been very competitive and successful in identifying four talented postdoctoral scientists committed to ovarian cancer research from a pool of 20 talented applicants. The postdoctoral scientists work with faculty at Dana Farber/Harvard Cancer Center in the fields of oncogenesis, signal transduction, pathology and mouse models, and cell biology. The following postdoctoral scientists have been funded with this training award:
- Dr. Ronny Drapkin has been developing new approaches to early detection using oligonucleotide micro-array analysis for the identification of genes expressed in ovarian cancer. He demonstrated that a newly discovered human epididymis protein 4 (HE4) is overexpressed in primary tumors and ovarian cancer cell lines. Dr. Drapkin is trying to determine the utility of HE4 as a serum biomarker for early detection.
- Dr. John Miao is studying the role of the desmosomal junction protein hepsin in the progression of ovarian cancer
- Dr. Sanja Sale has been focusing on the role of the serine threonine kinase mammalian target of Rapamycin (mTOR), in ovarian tumor progression. mTOR is involved in the regulation of cell growth through initiation of gene translation in response to nutrients, growth factors, insulin, and mitogens. Dr. Sale's main objective is to evaluate mTOR as a potential therapeutic target in epithelial ovarian cancer.
- Dr. Yong Zhan is focusing on the function of the Mullerian inhibitory substance (MIS) and its receptor in the development of the Mullerian epithelium. MIS, its receptor, and associated downstream signaling partners are targets for interventions for the treatment of epithelial ovarian carcinoma.
The mentoring program and training provided by the faculty at Dana Farber/Harvard Cancer Center have been especially successful at advancing the career of Dr. Drapkin. Dr. Drapkin recently left the training program to accept a faculty position in the Division of Molecular Pathology at Dana Farber Cancer Center. Additionally, he is the recipient of a transition grant from the Ovarian Cancer Research Foundation and a Mentored Clinical Scientist award from the National Cancer Institute, both of which are enabling him to launch his independent research career in ovarian cancer.
Drapkin R, von Horsten HH, Lin Y, et al. 2005. Human epididymis protein 4 (HE4) is a secreted glycoprotein that is overexpressed by serous and endometrioid ovarian carcinomas. Cancer Res 65:2162-2169.
Drapkin R, Crum CP, and Hecht J. 2004. Expression of candidate tumor markers in ovarian carcinoma and benign ovary: Evidence for a link between epithelial phenotype and neoplasia. Hum Pathol 35:1014-1021.