- Ovarian Autoantibodies Predict Ovarian Cancer
- Structural and Functional Analysis of CA125: Potential for Early Diagnosis and Understanding the Immune Evasion Strategies of Epithelial Ovarian Tumors
- Mumps Parotitis and Ovarian Cancer: Modern Significance of an Historic Association
- Targeting Ovarian Cancer
Ovarian cancer affects approximately 25,000 women annually. Many of these cases are diagnosed at later stages, and often less than 20% of these women survive. Discovering biomarkers for early detection of ovarian cancer is essential for improving survival rates because there is no effective screening test in women who have neither symptoms nor physical findings of ovarian cancer. Dr. Luborsky, recipient of a 2007 Department of Defense Ovarian Cancer Research Program Concept Award, utilized the egg-laying hen, a spontaneous animal model of ovarian cancer, to test the hypothesis that hens with anti-ovarian autoantibodies show a higher probability of developing ovarian cancer and, subsequently, that the anti-ovarian autoantibodies could be potentially used as a novel biomarker of ovarian cancer. The egg-laying hen Gallus domesticus is a novel animal model of ovarian cancer as the ovarian tumors that develop in these hens share many histological and physiological features with human ovarian tumors. Dr. Luborsky compared the proportion of hens with serum anti-ovarian autoantibodies to hens without anti-ovarian autoantibodies for development of ovarian cancer. Anti-ovarian antibodies tended to be associated with reduced ovarian function. Significantly, the results showed that only the hens with anti-tumor (ovarian) antibodies showed evidence of tumor angiogenesis, a surrogate marker of early ovarian cancer.
Additionally, Dr. Luborsky's group demonstrated for the first time that mesothelin (MSLN), a well characterized human ovarian cancer-specific antigen, is expressed in hen ovarian tumors. There was significant MSLN mRNA and protein expression in hen ovarian tumors compared to normal ovaries. Moreover, there were significant levels of circulating anti-MSLN antibodies only in hens with ovarian tumors expressing MSLN; hens with normal ovaries or tumors without MSLN expression showed no expression. Consequently, Dr. Luborsky demonstrated that this novel animal model could be a valuable preclinical model for the evaluation of MSLN-targeted immunotherapy. 
Furthermore, extensive epidemiological research has associated infertility with increased ovarian cancer risk in women. However, there was no test to determine which women among those with infertility might have a high risk for ovarian cancer. Dr. Luborsky determined whether women with infertility have antibodies to mesothelin. Sera were compared between women with infertility, women with ovarian cancer, healthy women, and other control groups for MSLN antibodies and circulating MSLN antigen. Mesothelin antibodies were significantly higher in women with prematurely reduced ovarian function including ovulatory dysfunction (59%), premature ovarian failure (44%) and unexplained infertility (25%) compared to the control groups. Dr. Luborsky's findings suggest that women with infertility and earlier than expected reductions in ovarian function, may have a higher ovarian cancer risk. Consequently, these results further support mesothelin and mesothelin autoantibodies as a strong novel biomarker for ovarian cancer .
 Yu Y, Edassery SL, Barua A, Abramowicz JS, Bahr JM, Hellstrom I, and Luborsky JL. 2011. The hen model of human ovarian cancer develops anti-mesothelin autoantibodies in response to mesothelin expressing tumors. Journal of Ovarian Research 4:12. PMID: 21801396
 Luborsky JL, Yu Y, Edassery SL, Jaffar J, Yip YY, Liu P, Hellstrom KE, and Hellstrom I. 2011. Autoantibodies to mesothelin in infertility. Cancer Epidemiology, Biomarkers & Prevention 20(9):1970-1978. PMID: 21846819
Structural and Functional Analysis of CA125: Potential for Early Diagnosis and Understanding the Immune Evasion Strategies of Epithelial Ovarian Tumors
Posted September 29, 2011
Manish Patankar, Ph.D., University of Wisconsin, Madison
Dr. Manish Patankar, of the University of Wisconsin, Madison, received a fiscal year 2003 (FY03) Idea Development Award from the Department of Defense Ovarian Cancer Research Program (DoD OCRP). The award supported Dr. Patankar's investigation into the biological role of the ovarian tumor mucin MUC16 , a large molecular weight molecule that contains repeating peptide epitopes more commonly known as CA125. Funding from the award helped Dr. Patankar and his co-investigators demonstrate that ovarian cancer cells use MUC16 to metastasize in the peritoneal cavity. The research team conducted studies to define the kinetics of MUC16 binding to mesothelin, a glycoprotein expressed on mesothelial cells . The binding of MUC16 to mesothelin allows cancer cells to attach to the mesothelial cells. The researchers further demonstrated that removal of the N-linked oligosaccharide chains of MUC16 inhibits the binding ability of the mucin to mesothelin .
Dr. Patankar and his colleagues demonstrated that in addition to aiding in the metastasis of ovarian cancer cells, MUC16 is a potent inhibitor of the cytotoxicity of human natural killer (NK) cells . The NK cells are a major arm of the innate immune system and they mediate an anti-cancer response. Analysis of NK cells and monocytes isolated from the peripheral blood and peritoneal fluid of ovarian cancer patients showed that these immune cells were positive for MUC16 [4,5]. The team conducted extensive experiments proving that the immune cells were not expressing endogenous MUC16 but were instead binding to the mucin that was being released by the ovarian cancer cells. They have now demonstrated that MUC16 binds to the I-type lectin Siglec-9, which is expressed by NK cells and monocytes. Siglec-9 is an inhibitory receptor and the researchers believe that the binding of MUC16 to Siglec-9 results in negative signaling in the immune cells whereby they are unable to react against the ovarian cancer cells . In addition to suppressing immune cell function via Siglec-9, MUC16 - because of its large size and high negative charge - also shields the ovarian cancer cells from NK cells . Thus, the ovarian cancer cells are utilizing MUC16 as a major mechanism to evade immune attack.
The binding of MUC16 to the immune cells suggests that, in addition to determining the serum levels of CA125, immune cell-bound MUC16 may also serve as an alternate method for diagnosis and monitoring of ovarian cancer. Indeed, Dr. Patankar's data indicates that the immune cell-bound MUC16 provides positive results even when the serum CA125 levels are low-to-undetectable. The group is conducting analysis of serial samples isolated from ovarian cancer patients to determine if the immune cell-bound MUC16 can serve as a better marker for disease recurrence than the serum CA125 assay. These observations have also led Dr. Patankar and his team to investigate whether there may be other biomarkers, in addition to MUC16, in the transcriptome and proteome of immune cells of ovarian cancer patients. These new studies are the basis for Dr. Patankar's FY10 Pilot Award through the OCRP - Mining the Immune Cell Proteome to Identify Ovarian Cancer-Specific Biomarkers.
 Gubbels JAA, Claussen N, Kapur AK, Connor JP, and Patankar MS. 2009. Detection, treatment, and the biology of epithelial ovarian cancer. Journal of Ovarian Research 2:8.
 Gubbels JA, Belisle J, Onda M, Rancourt C, Migneault M, Ho M, Bera TK, Connor J, Sathyanarayana BK, and Lee B. 2006. Mesothelin-MUC16 binding is a high affinity, N-glycan dependent interaction that facilitates peritoneal metastasis of ovarian tumors. Molecular Cancer 5:50.
 Patankar MS, Yu J, Morrison JC, Belisle JA, Lattanzio FA, Deng Y, Wong NK, Morris HR, Dell A, and Clark GF. 2005. Potent suppression of natural killer cell response mediated by the ovarian tumor marker CA125. Gynecologic Oncology 99:704-713.
 Belisle JA, Gubbels JA, Raphael CA, Migneault M, Rancourt C, Connor JP, and Patankar MS. 2007. Peritoneal natural killer cells from epithelial ovarian cancer patients show an altered phenotype and bind to the tumour marker MUC16 (CA125). Immunology 122:418-429.
 Belisle JA, Horibata S, Gubbels JA, Petrie S, Kapur A, Andre S, Gabius HJ, Rancourt C, Connor J, Paulson JC, and Patankar MS. 2010. Identification of Siglec-9 as the receptor for MUC16 on human NK cells, B cells, and monocytes. Molecular Cancer 9:118.
 Gubbels JAA, Felder M, Horibata S, Belisle JA, Holden H, Petrie S, Migneault M, Rancourt C, Connor JP, and Patankar MS. 2009. MUC16 provides immune protection by inhibiting synapse formation between NK and ovarian tumor cells. Molecular Cancer 9:11.
A study from 1966 found that women with ovarian cancer were less likely to report having childhood mumps than women with benign ovarian cysts suggesting mumps may be protective against ovarian cancer. Additional epidemiologic studies confirmed that a history of mumps may be associated with a lower risk for ovarian cancer, but none of these studies offered a clear explanation as to why.
Dr. Daniel W. Cramer of Brigham and Women's Hospital decided to look for a biological reason for this long-forgotten association. With the DOD OCRP Concept award which provides funds for scientists to challenge or expand current thinking and approaches, Dr. Cramer hypothesized that the expression of a tumor-like form of mucin 1 (MUC1) during an acute inflammatory event, like mumps parotitis, may induce anti-MUC1 antibodies, which could later recognize the same form of MUC1 from an early ovarian tumor and lead to an immune reaction that could eliminate an early ovarian tumor-a process called immunosurveillance.
Dr. Cramer summarized data from eight case-control studies related to mumps and ovarian cancer and showed the summary results were consistent with a protective effect of mumps parotitis against ovarian cancer. Surveying health agencies and obtaining specimens that had been collected from individuals with a mumps infection, he measured levels of anti-MUC1 antibodies, MUC1, and CA-125 in serum samples comparing the mumps cases to healthy age- and sex-matched controls. As hypothesized, he observed that anti-MUC1 antibody levels were higher in cases with mumps than the controls, particularly in younger individuals and females. CA-125 was also higher in the serum of cases. Dr. Cramer concluded that additional studies about the specific immune changes that occur during a mumps infection may further explain its potential beneficial effect on ovarian cancer and provide clues for duplicating this effect in the post-vaccination era when childhood mumps seldom occurs.
Cramer DW, Vitonis AF, Pinheiro SP, McKolanis JR, Fichorova RN, Brown KE, Hatchette TF, and Finn OJ. Mumps and ovarian cancer: modern interpretation of an historic association. Cancer Causes Control. 2010;21:1193-201.2951028
Susan K. Murphy is an assistant professor in the departments of Obstetrics and Gynecology and Pathology at Duke University. A common theme in many of Dr. Murphy's publications is the molecular basis of ovarian cancer. Her research interests include identification of methylation biomarkers of disease, ovarian cancer stem cells, chemotherapeutic response in ovarian cancer, tumor dormancy and the influence of the in utero environment on DNA methylation, and risk of disease.
Dr. Murphy received an FY04 OCRP Idea Development Award titled "Epigenetic Characterization of Ovarian Cancer," which sought to understand the contribution of epigenetic regulation, an alternative form of gene regulation, to ovarian cancer. Her team identified and validated a large number of genes that were targeted by DNA methylation as a mechanism to repress their transcription. Her findings are important not only because they add significantly to our knowledge about the gene set that becomes epigenetically deregulated in ovarian malignancies, but they also have the potential to directly affect patient care. In the greater research world her work has generated a great deal of interest, as is evident in the publications (listed below) and five successful funding applications resulting from this work.
In FY10, Dr. Murphy received a Translational Pilot Award for her current project, "Preemptive Approach to Improving Survival in Epithelial Ovarian Cancer." Her objective is to determine whether drugs that more effectively kill slow-growing cells are able to reduce or eliminate tumor growth in a mouse model of recurrent ovarian cancer. Hopefully, this study will be a springboard for the initiation of clinical trials that may lead to incorporation of her approach in treating women with advanced-stage ovarian cancer. While patients are typically treated with drugs that only target fast-growing cancer cells, Dr. Murphy's research, should it yield promising results, may increase the number of survivors because they will receive additional treatment (likely while in remission) to eradicate the remaining slow-growing cells.
Matsumura N, Huang Z, Baba T, Mori S, Fujii S, Konishi I, Berchuck A, and Murphy SK. 2011. Epigenetic suppression of the TGF-beta pathway revealed by transcriptome profiling in ovarian cancer. Genome Research 21:74-82.
Kondoh E, Mori S, Yamaguchi K, Baba T, Matsumura N, Barnett JC, Whitaker RS, Konishi I, Fujii S, Berchuck A, and Murphy SK. 2010. Targeting slow proliferating quiescent ovarian cancer cells. International Journal of Cancer 126:2448-2456.
Lee PS, Teaberry VS, Bland AE, Huang Z, Whitaker RS, Baba T, Fujii S, Secord AA, Berchuck A, and Murphy SK. 2010. Elevated MAL expression is accompanied by promoter hypomethylation and platinum resistance in epithelial ovarian cancer. International Journal of Cancer 126:1378-1389.
Murphy SK. 2010. Targeting ovarian cancer-initiating cells. Anticancer Agents in Medicinal Chemistry 10:157-163.
Baba T, Convery P, Matsumura N, Whitaker RS, Perry T, Huang Z, Bentley RC, Mori S, Fujii S, Marks JR, Berchuck A, and Murphy SK. 2009. Epigenetic regulation of CD133 and tumorigenicity of CD133(+) ovarian cancer cells. Oncogene 28(2):209-218.
Matsumura N, Huang Z, Baba T, Lee PS, Mori S, Chang J, Kuo W, Gusberg AH, Whitaker RS, Gray JW, Fujii S, Berchuck A, and Murphy SK. 2009. Yin yang 1 modulates taxane response in epithelial ovarian cancer. Molecular Cancer Research 7(2):210-220.
Goh L, Murphy SK, Mukherjee S, and Furey TS. 2007. Genomic sweeping for hypermethylated genes. Bioinformatics 23(3):281-288.
Weidman JR, Dolinoy DC, Murphy SK, and Jirtle RL. 2007. Cancer susceptibility: Epigenetic manifestation of environmental exposures. Cancer Journal 13(1):9-16.