Denise C. Connolly

Focus on epithelial ovarian cancer

Epithelial ovarian cancer (EOC) will be diagnosed in 24,400women in the United States in 2004, with an estimated 14,300deaths (Jemal et al., 2003).Neoplasms from the surface epithe-lium of the ovary exhibit a variety of Mullerian-type cells, includ-ing serous, mucinous, endometrioid, and clear cell, reflecting acommon pathway in embryological development.In the westernworld, EOC is the most lethal gynecologic cancer, accountingfor more deaths than endometrial and cervical cancer com-bined. Spread of the disease via the lymphatics and by peri-toneal implantation is not associated with any specific signs orsymptoms, and the vast majority of women are diagnosed withdisseminated intraperitoneal carcinomatosis (FIGO Stage III).Also contributing to the high mortality is the advanced age atdiagnosis (median 63 years), with an increase aftermenopause. While ultrasound and computerized tomogramsare useful in definition of sites of bulk disease, surgical evalua-tion is necessary for accurate staging and to remove largemetastases (cytoreduction). Due to the propensity for diffusesmall-volume disease, surgery is rarely able to render patientsdisease free, and postoperative chemotherapy is usuallyrequired. While overall mortality rates have remained relativelyconstant for the past two to three decades, five-year survivalrates have increased from 30% in the 1960s to over 50% in thepast several years.

RAD001 (Everolimus) Delays Tumor Onset and Progression in a Transgenic Mouse Model of Ovarian Cancer

The mammalian target of rapamycin (mTOR) is thought to play a critical role in regulating cell growth, cell cycle progression, and tumorigenesis. Because the AKT-mTOR pathway is frequently hyperactivated in ovarian cancer, we hypothesized that the mTOR inhibitor RAD001 (Everolimus) would inhibit ovarian tumorigenesis in transgenic mice that spontaneously develop ovarian carcinomas. We used TgMISIIR-TAg transgenic mice, which develop bilateral ovarian serous adenocarcinomas accompanied by ascites and peritoneal dissemination. Fifty-eight female TgMISIIR-TAg mice were treated with 5 mg/kg RAD001 or placebo twice weekly from 5 to 20 weeks of age. To monitor tumor development, mice were examined biweekly using magnetic resonance microimaging. In vivo effects of RAD001 on Akt-mTOR signaling, tumor cell proliferation, and blood vessel area were analyzed by immunohistochemistry and Western blot analysis. RAD001 treatment markedly delayed tumor development. Tumor burden was reduced by approximately 84%. In addition, ascites formation, together with peritoneal dissemination, was detected in only 21% of RAD001-treated mice compared with 74% in placebo-treated animals. Approximately 30% of RAD001-treated mice developed early ovarian carcinoma confined within the ovary, whereas all placebo-treated mice developed advanced ovarian carcinoma. Treatment with RAD001 diminished the expression of vascular endothelial growth factor in tumor-derived cell lines and inhibited angiogenesis in vivo. RAD001 also attenuated the expression of matrix metalloproteinase-2 and inhibited the invasiveness of tumor-derived cells. Taken together, these preclinical findings suggest that mTOR inhibition, alone or in combination with other molecularly targeted drugs, could represent a promising chemopreventive strategy in women at high familial risk of ovarian cancer.

Molecular Genetic Alterations in Radiation-Induced Astrocytomas

Astrocytic tumors occasionally arise in the central nervous system following radiotherapy. It is not clear if these gliomas represent a unique molecular genetic subset. We identified nine cases in which an astrocytoma arose within ports of previous radiation therapy, with total doses ranging from 2400 to 5500 cGy. Irradiated primary lesions included craniopharyngioma, pituitary adenoma, Hodgkins lymphoma, ependymoma, pineal neoplasm, rhabdomyosarcoma, and three cases of lymphoblastic malignancies. Patients ranged from 9 to 60 years of age and developed secondary tumors 5 to 23 years after radiotherapy. The 9 postradiation neoplasms presented as either anaplastic astrocytoma (3 cases) or glioblastoma multiforme (6 cases). Two of the latter contained malignant mesenchymal components. We performed DNA sequence analysis, differential polymerase chain reaction (PCR), and quantitative PCR on DNA from formalin-fixed, paraffin-embedded tumors to evaluate possible alterations of p53, PTEN, K-ras, EGFR, MTAP, and p16 (MTS1/CDKN2) genes. By quantitative PCR, we found EGFR gene amplification in 2 of 8 tumors. One of these demonstrated strong immunoreactivity for EGFR. Quantitative PCR showed chromosome 9p deletions including p16 tumor suppressor gene (2 of 7 tumors) and MTAP gene (3 of 7). Five of 9 tumors demonstrated diffuse nuclear immunoreactivity for p53 protein. Sequencing of the p53 gene in these 9 cases revealed a mutation in only one of these cases, a G-to-A substitution in codon 285 (exon 8). Somewhat unexpectedly, no mutations were identified in PTEN, a commonly altered tumor suppressor gene in de novo glioblastoma multiformes. Unlike some radiation-induced tumors, no activating point mutations of the K-ras proto-oncogene or base pair deletions of tumor suppressor genes were noted. These radiation-induced tumors are distinctive in their high histological grade at clinical presentation. The spectrum of molecular genetic alterations appears to be similar to that described in spontaneous high grade astrocytomas, especially those of the de novo type.

NEDD9 Promotes Oncogenic Signaling in Mammary Tumor Development

In the past 3 years, altered expression of the HEF1/CAS-L/NEDD9 scaffolding protein has emerged as contributing to cancer metastasis in multiple cancer types. However, whereas some studies have identified elevated NEDD9 expression as prometastatic, other work has suggested a negative role in tumor progression. We here show that the Nedd9-null genetic background significantly limits mammary tumor initiation in the MMTV-polyoma virus middle T genetic model. Action of NEDD9 is tumor cell intrinsic, with immune cell infiltration, stroma, and angiogenesis unaffected. The majority of the late-appearing mammary tumors of MMTV-polyoma virus middle T;Nedd9(-/-) mice are characterized by depressed activation of proteins including AKT, Src, FAK, and extracellular signal-regulated kinase, emphasizing an important role of NEDD9 as a scaffolding protein for these prooncogenic proteins. Analysis of cells derived from primary Nedd9(+/+) and Nedd9(-/-) tumors showed persistently reduced FAK activation, attachment, and migration, consistent with a role for NEDD9 activation of FAK in promoting tumor aggressiveness. This study provides the first in vivo evidence of a role for NEDD9 in breast cancer progression and suggests that NEDD9 expression may provide a biomarker for tumor aggressiveness.

Cyclooxygenase-1 Is Overexpressed in Multiple Genetically Engineered Mouse Models of Epithelial Ovarian Cancer

Cyclooxygenases-1 and -2 (Cox-1 and Cox-2) are two distinct isoforms that catalyze the conversion of arachidonic acid to prostaglandins. The role of Cox-2 in a variety of cancers is well recognized, but the contribution of Cox-1 remains much less explored. We have previously shown that human epithelial ovarian tumors have increased levels of Cox-1, but not Cox-2. We also observed that Cox-1 is highly expressed in a mouse model of epithelial ovarian cancer (EOC), which lacks p53 but overexpresses c-myc and K-ras or c-myc and Akt. More importantly, a Cox-1-selective inhibitor, SC-560, attenuates EOC growth. In the present investigation, we used various genetically engineered mouse models of EOC to determine whether Cox-1 overexpression is unique to specific genetic and oncogenic alterations or is widespread. These models include: (a) deletion of both p53 and Rb, (b) induction of the transforming region of SV40 under the control of Mullerian inhibitory substance type II receptor, or (c) activation of K-Ras in the absence of Pten locally in the ovarian surface epithelium. We found that these three models, which produce spontaneous EOC, also show up-regulated expression of Cox-1, but not Cox-2. The results provide further evidence that Cox-1 overexpression is common in various models of EOC. Thus, Cox-1 serves as a potential marker of EOC and is a possible target for the prevention and/or treatment of this deadly disease.

Resistance to BET Bromodomain Inhibitors Is Mediated by Kinome Reprogramming in Ovarian Cancer

Small-molecule BET bromodomain inhibitors (BETis) are actively being pursued in clinical trials for the treatment of a variety of cancers, but the mechanisms of resistance to BETis remain poorly understood. Using a mass spectrometry approach that globally measures kinase signaling at the proteomic level, we evaluated the response of the kinome to targeted BETi treatment in a panel of BRD4-dependent ovarian carcinoma (OC) cell lines. Despite initial inhibitory effects of BETi, OC cells acquired resistance following sustained treatment with the BETi JQ1. Through application of multiplexed inhibitor beads (MIBs) and mass spectrometry, we demonstrate that BETi resistance is mediated by adaptive kinome reprogramming, where activation of compensatory pro-survival kinase networks overcomes BET protein inhibition. Furthermore, drug combinations blocking these kinases may prevent or delay the development of drug resistance and enhance the efficacy of BETi therapy.

Magnetic resonance imaging for detection and determination of tumor volume in a genetically engineered mouse model of ovarian cancer

Our laboratory developed a transgenic mouse model of spontaneous epithelial ovarian cancer (EOC) in which tumors are initiated by expression of the early region of the Simian Virus 40 (SV40) under transcriptional control of the 5’ upstream regulatory region of the Müllerian inhibiting substance type II receptor (MISIIR) gene. Female TgMISIIR-TAg-DR26 transgenic mice develop bilateral ovarian tumors with variable latency and survive an average of 152 days. In the absence of reliable methods for disease detection and evaluation of therapeutic response, preclinical studies of this transgenic mouse model of EOC would be limited to longitudinal experiments involving large numbers of animals with euthanasia as the endpoint. Therefore, a non-invasive method for detecting tumors, measuring tumor volume and calculating parameters relevant to the evaluation of therapeutic or preventive interventions (i.e., tumor growth rates, tumor initiation, tumor regression and the time for tumors to reach a given size) is required. We developed and optimized a non-invasive Magnetic Resonance Imaging (MRI) scanning protocol to obtain high resolution abdominal images that is well tolerated by mice. Superior contrast and contrast to noise ratio (CNR) was found with Gd-DTPA contrast enhanced T1-weighted sequences. Image sets in both the axial and coronal orientations for redundant measurements of normal ovary and ovarian tumor volume can be acquired in approximately 20 minutes. Accuracy of MRI-based ovary and tumor volume determinations was verified by standard volume measurements at necropsy. Serial imaging studies were performed on 41 ovarian cancer bearing TgMISIIR-TAg-DR26 transgenic mice to quantitate tumor progression over time in this model. A chemotherapy study was conducted on TgMISIIR-TAg-DR26 transgenic mice using a standard combination therapy consisting of cisplatin and paclitaxel. Our results demonstrate that MRI is well tolerated and can be repeated in serial imaging studies, permitting quantitative analysis of tumor growth and progression and response to therapeutic interventions.

Somatic mutations of fibroblast growth factor receptor 3 (FGFR3) are uncommon in carcinomas of the uterine cervix.

Germline mutations of the gene encoding human fibroblast growth factor receptor 3 (FGFR3) have been shown to be responsible for several related autosomal dominant forms of syndromic craniosynostosis and short limb dwarfism. Somatic activating mutations of FGFR3 were recently reported to occur in three of 12 (25%) uterine cervical carcinomas and nine of 26 (35%) bladder carcinomas, suggesting that constitutive activation of FGFR3 may be an important mechanism underlying the development and/or progression of these common epithelial malignancies. In order to investigate further a possible role for FGFR3 mutations in cervical carcinogenesis, we performed sequence-based mutational analysis of FGFR3 in 51 primary cervical carcinomas and seven cervical carcinoma-derived cell lines. The regions analysed (exons 7, 10, 13, 15, and 19) encompassed all previously described FGFR3 mutations. A single nucleotide substitution at codon 249, predicting a serine to cysteine amino acid substitution (S249C) in the FGFR3 extracellular domain, was identified in one primary tumor. Only wild type FGFR3 alleles were identified in the remaining tumors and cell lines. The S249C mutation is the only FGFR3 mutation described to date in cervical carcinomas. These findings suggest that while activating mutations of FGFR3 occur in cervical cancer, they may not be as common as initially reported.

Targeted Blockade of JAK/STAT3 Signaling Inhibits Ovarian Carcinoma Growth

Ovarian carcinoma is the fifth leading cause of death among women in the United States. Persistent activation of STAT3 is frequently detected in ovarian carcinoma. STAT3 is activated by Janus family kinases (JAK) via cytokine receptors, growth factor receptor, and non–growth factor receptor tyrosine kinases. Activation of STAT3 mediates tumor cell proliferation, survival, motility, invasion, and angiogenesis, and recent work demonstrates that STAT3 activation suppresses antitumor immune responses and supports tumor-promoting inflammation. We hypothesized that therapeutic targeting of the JAK/STAT3 pathway would inhibit tumor growth by direct effects on ovarian carcinoma cells and by inhibition of cells in the tumor microenvironment (TME). To test this, we evaluated the effects of a small-molecule JAK inhibitor, AZD1480, on cell viability, apoptosis, proliferation, migration, and adhesion of ovarian carcinoma cells in vitro. We then evaluated the effects of AZD1480 on in vivo tumor growth and progression, gene expression, tumor-associated matrix metalloproteinase (MMP) activity, and immune cell populations in a transgenic mouse model of ovarian carcinoma. AZD1480 treatment inhibited STAT3 phosphorylation and DNA binding, and migration and adhesion of cultured ovarian carcinoma cells and ovarian tumor growth rate, volume, and ascites production in mice. In addition, drug treatment led to altered gene expression, decreased tumor-associated MMP activity, and fewer suppressor T cells in the peritoneal TME of tumor-bearing mice than control mice. Taken together, our results show pharmacologic inhibition of the JAK2/STAT3 pathway leads to disruption of functions essential for ovarian tumor growth and progression and represents a promising therapeutic strategy. Mol Cancer Ther; 14(4); 1035–47. ©2015 AACR.

Aurora kinase A mediates epithelial ovarian cancer cell migration and adhesion

Aurora kinase A (AURKA) localizes to centrosomes and mitotic spindles where it mediates mitotic progression and chromosomal stability. Overexpression of AURKA is common in cancer, resulting in acquisition of alternate non-mitotic functions. In the current study, we identified a novel role for AURKA in regulating ovarian cancer cell dissemination and evaluated the efficacy of an AURKA-selective small molecule inhibitor, alisertib (MLN8237), as a single agent and combined with paclitaxel using an orthotopic xenograft model of epithelial ovarian cancer (EOC). Ovarian carcinoma cell lines were used to evaluate the effects of AURKA inhibition and overexpression on migration and adhesion. Pharmacological or RNA interference-mediated inhibition of AURKA significantly reduced ovarian carcinoma cell migration and adhesion and the activation-associated phosphorylation of the cytoskeletal regulatory protein SRC at tyrosine 416 (pSRCY416). Conversely, enforced expression of AURKA resulted in increased migration, adhesion and activation of SRC in cultured cells. In vivo tumor growth and dissemination were inhibited by alisertib treatment as a single agent. Moreover, combination of alisertib with paclitaxel, an agent commonly used in treatment of EOC, resulted in more potent inhibition of tumor growth and dissemination compared with either drug alone. Taken together, these findings support a role for AURKA in EOC dissemination by regulating migration and adhesion. They also point to the potential utility of combining AURKA inhibitors with taxanes as a therapeutic strategy for the treatment of EOC patients.