Principles of ethics and critical communication during the COVID-19 pandemic

•During the COVID-19 pandemic, the primary clinical emphasis has shifted to optimizing community health. •Scarce resources should be allocated to maximize benefit without unfairly affecting any group. •Healthcare systems should consider adopting a formal, tier-based response to COVID-19 related demand on resources. •Clinicians should use principles of high-stakes communication to guide care planning during the pandemic.

CBX2 identified as driver of anoikis escape and dissemination in high grade serous ovarian cancer

High grade serous ovarian carcinoma (HGSOC) is often diagnosed at an advanced stage. Chromobox 2 (CBX2), a polycomb repressor complex subunit, plays an oncogenic role in other cancers, but little is known about its role in HGSOC. We hypothesize that CBX2 upregulation promotes HGSOC via induction of a stem-like transcriptional profile and inhibition of anoikis. Examination of Gene Expression Omnibus (GEO) datasets and The Cancer Genome Atlas (TCGA) established that increased CBX2 expression conveyed chemoresistance and worse disease-free and overall survival. In primary HGSOC tumors, we observed CBX2 expression was significantly elevated compared to benign counterparts. In HGSOC cell lines, forced suspension promoted CBX2 expression. Subsequently, CBX2 knockdown inhibited anchorage-independent proliferation and potentiated anoikis-dependent apoptosis. Furthermore, CBX2 knockdown re-sensitized cells to platinum-based chemotherapy. Forced suspension promoted increased ALDH activity and ALDH3A1 expression and CBX2 knockdown led to a decrease in both ALDH activity and ALDH3A1 expression. Investigation of CBX2 expression on a HGSOC tissue microarray revealed CBX2 expression was apparent in both primary and metastatic tissues. CBX2 is an important regulator of stem-ness, anoikis escape, HGSOC dissemination, and chemoresistance and potentially serves as a novel therapeutic target.

Fascin Is Associated With Aggressive Behavior and Poor Outcome in Uterine Carcinosarcoma

OBJECTIVE

The mechanisms underlying the histogenesis and aggressiveness of uterine carcinosarcoma (UCS) are poorly understood; however, previous studies implicate epithelial-mesenchymal transition (EMT). Fascin is a proinvasive, actin-bundling protein and an important component of EMT. It is associated with poor outcomes in human carcinoma, especially in estrogen receptor (ER)-negative tumors arising in organs normally expressing ER. We sought to evaluate fascin expression in UCS and its relationship to ER status, clinicopathologic indicators of tumor aggressiveness, and survival outcomes.

METHOD

Forty-four surgically staged cases of UCS were immunohistochemically evaluated for fascin and estrogen receptor-α expression and correlated with clinicopathologic parameters derived from electronic medical records and pathology reports.

RESULTS

Fascin was only expressed in malignant epithelium and mesenchyma and was uniformly absent in background benign counterparts. Increased expression was associated with extrapelvic disease (P = 0.028), higher stage (P = 0.021), larger tumor size (P = 0.032), shorter progression-free interval (P = 0.035), and reduced estrogen receptor-α expression (P = 0.04).

CONCLUSION

Fascin is aberrantly expressed in both elements of UCS and is associated with aggressive behavior and worse outcome. As a component of EMT and mediator of invasion, fascin may serve as a target in future therapies.

A tRNA fragment, tRF5-Glu, regulates BCAR3 expression and proliferation in ovarian cancer cells

Ovarian cancer is a complex disease marked by tumor heterogeneity, which contributes to difficulties in diagnosis and treatment. New molecular targets and better molecular profiles defining subsets of patients are needed. tRNA fragments (tRFs) offer a recently identified group of noncoding RNAs that are often as abundant as microRNAs in cancer cells. Initially their presence in deep sequencing data sets was attributed to the breakdown of mature tRNAs, however, it is now clear that they are actively generated and function in multiple regulatory events. One such tRF, a 5’ fragment of tRNA-Glu-CTC (tRF5-Glu), is processed from the mature tRNA-Glu and is shown in this study to be expressed in ovarian cancer cells. We confirmed that tRF5-Glu binds directly to a site in the 3’UTR of the Breast Cancer Anti-Estrogen Resistance 3 (BCAR3) mRNA thereby down regulating its expression. BCAR3 has not previously been studied in ovarian cancer cells and our studies demonstrate that inhibiting BCAR3 expression suppresses ovarian cancer cell proliferation. Furthermore, mimics of tRF5-Glu were found to inhibit proliferation of ovarian cancer cells. In summary, BCAR3 and tRF5-Glu contribute to the complex tumor heterogeneity of ovarian cancer cells and may provide new targets for therapeutic intervention.

PTTG1 Levels Are Predictive of Saracatinib Sensitivity in Ovarian Cancer Cell Lines

Src kinase is recognized as a key target for molecular cancer therapy. However, methods to efficiently select patients responsive to Src inhibitors are lacking. We explored the sensitivity of ovarian cancer cell lines to the Src kinase inhibitor saracatinib to identify predictive markers of drug sensitivity using gene microarrays. Pituitary tumor transforming gene 1 (PTTG1) was selected as a potential biomarker as mRNA levels were correlated with saracatinib resistance, as well as higher PTTG1 protein expression. PTTG1 expression was correlated with proliferation, cell division, and mitosis in ovarian cancer tissues data sets. In sensitive cell lines, saracatinib treatment decreased PTTG1 and fibroblast growth factor 2 (FGF2) protein levels. Downregulating PTTG1 by siRNAs increased saracatinib sensitivity in two resistant cell lines. Our results indicate PTTG1 may be a valuable biomarker in ovarian cancer to predict sensitivity to saracatinib, and could form the basis of a targeted prospective saracatinib trial for ovarian cancer.

Claudin-4 activity in ovarian tumor cell apoptosis resistance and migration

Background

Claudin-4 is a transmembrane protein expressed at high levels in the majority of epithelial ovarian tumors, irrespective of subtype, and has been associated with tumor cells that are both chemoresistant and highly mobile. The objective of this study was to determine the functional role that claudin-4 plays in apoptosis resistance and migration as well as the therapeutic utility of targeting claudin-4 activity with a small mimic peptide.

Methods

We examined claudin-4 activity in human ovarian tumor cell lines (SKOV3, OVCAR3, PEO4) using in vitro caspase and scratch assays as well as an in vivo mouse model of ovarian cancer. Claudin-4 activity was disrupted by treating cells with a small peptide that mimics the DFYNP sequence in the second extracellular loop of claudin-4. Claudin-4 expression was also altered using shRNA-mediated gene silencing.

Results

Both the disruption of claudin-4 activity and the loss of claudin-4 expression significantly increased tumor cell caspase-3 activation (4 to 10-fold, respectively) in response to the apoptotic inducer staurosporine and reduced tumor cell migration by 50 %. The mimic peptide had no effect on cells that lacked claudin-4 expression. Female athymic nude mice bearing ZsGreen-PEO4 ovarian tumors showed a significant decrease in ovarian tumor burden, due to increased apoptosis, after treatment with intraperitoneal injections of 4 mg/kg mimic peptide every 48 h for three weeks, compared to control peptide treated mice.

Conclusion

Claudin-4 functionally contributes to both ovarian tumor cell apoptosis resistance and migration and targeting extracellular loop interactions of claudin-4 may have therapeutic implications for reducing ovarian tumor burden.

Interactions with industry under the Sunshine Act: an example from gynecologic oncology

THE PROBLEM

Clinicians may be unaware that industry payments to physicians are now publicly searchable under the Physician Payments Sunshine Act. Furthermore, the extent of industry's financial involvement in subspecialty practice has not been previously accessible. As an example, 6948 direct, research-unrelated payments totaling $1,957,004 were made to 765 gynecologic oncologists in 2014, the first full year of data available. A total of 153 companies reported at least 1 payment; however, the 10 manufacturers reporting the highest total payment amount accounted for 82% of all payments to physicians. In all, 48 gynecologic oncologists received >$10,000 from manufacturers, accounting for $1,202,228, or 61%, of total payments.

A SOLUTION

Obstetrician-gynecologists, including gynecologic oncologists, should be aware of their publicly reported payments from industry and ensure reports' accuracy. Professional organizations, including the Society of Gynecologic Oncology (SGO), should strongly consider proactively developing guidelines regarding interactions with industry for their general memberships.

Progestin treatment decreases CD133+ cancer stem cell populations in endometrial cancer

OBJECTIVES

Endometrial cancer is a hormonally responsive malignancy. Response to progestins is associated with estrogen receptor (ER) and progesterone receptor (PR) status. CD133 is a marker of endometrial cancer stem cells. We postulated that CD133+ cells express ER and PR and that progestin therapy differentially regulates CD133+ cells.

METHODS

The Ishikawa (ER/PR positive) and KLE (ER/PR negative) cell lines were examined for the presence of CD133 populations. Cell lines were treated with 30.4μM medroxyprogesterone 17-acetate (MPA) for 6days. After treatment, cell counts, apoptosis assays and CD133+ populations were examined. In a clinical project, we identified 12 endometrial cancer patients who were treated with progestin drugs at our institution. Using immunohistochemistry, CD133, ER, PR, and androgen receptor (AR) expression was scored and evaluated for change over time on serial biopsies.

RESULTS

CD133+ populations were identified in Ishikawa and KLE cell lines. MPA treatment resulted in a significant reduction in the percentage of live cells (Ishikawa, P=0.036; KLE, P=0.0002), significant increase in apoptosis (Ishikawa, P=0.01; KLE, P=0.0006) and significant decrease in CD133+ populations (Ishikawa, P<0.0001; KLE, P=0.0001). ER, PR, AR and CD133 were present in 96.4%, 96.4%, 89.3% and 100% of patient samples respectively. Paralleling the in vitro results, CD133 expression decreased in patients who had histologic response to progestin treatment.

CONCLUSION

CD133+ populations decreased after treatment with MPA in an in vitro model and in patients responding to treatment with progestins. Progestin treatment differentially decreases CD133+ cells.

A phase II trial of brivanib in recurrent or persistent endometrial cancer: an NRG Oncology/Gynecologic Oncology Group Study

PURPOSE

Brivanib, an oral, multi-targeted tyrosine kinase inhibitor with activity against vascular endothelial growth factor (VEGF) and fibroblast growth factor receptor (FGFR) was investigated as a single agent in a phase II trial to assess the activity and tolerability in recurrent or persistent endometrial cancer (EMC).

PATIENTS AND METHODS

Eligible patients had persistent or recurrent EMC after receiving one to two prior cytotoxic regimens, measurable disease, and performance status of ≤2. Treatment consisted of brivanib 800 mg orally every day until disease progression or prohibitive toxicity. Primary endpoints were progression-free survival (PFS) at six months and objective tumor response. Expression of multiple angiogenic proteins and FGFR2 mutation status was assessed.

RESULTS

Forty-five patients were enrolled. Forty-three patients were eligible and evaluable. Median age was 64 years. Twenty-four patients (55.8%) received prior radiation. Median number of cycles was two (range 1-24). No GI perforations but one rectal fistula were seen. Nine patients had grade 3 hypertension, with one experiencing grade 4 confusion. Eight patients (18.6%; 90% CI 9.6%-31.7%) had responses (one CR and seven PRs), and 13 patients (30.2%; 90% CI 18.9%-43.9%) were PFS at six months. Median PFS and overall survival (OS) were 3.3 and 10.7 months, respectively. When modeled jointly, VEGF and angiopoietin-2 expression may diametrically predict PFS. Estrogen receptor-α (ER) expression was positively correlated with OS.

CONCLUSION

Brivanib is reasonably well tolerated and worthy of further investigation based on PFS at six months in recurrent or persistent EMC.

Lymphovascular space invasion in robotic surgery for endometrial cancer

BACKGROUND

Minimally invasive surgery has become a standard treatment for endometrial cancer and offers significant benefits over abdominal approaches. There are discrepant data regarding lymphovascular space invasion (LVSI) and positive peritoneal cytology with the use of a uterine manipulator, with previous small-scale studies demonstrating an increased incidence of these prognostically important events. We sought to determine if there was a higher incidence of LVSI in patients who underwent robot-assisted surgery for endometrial cancer.

METHODS

We performed a single-institution review of medical records for patients who underwent open abdominal or robot-assisted hysterectomy for endometrial cancer over a 24-month period. The following data were abstracted: age, tumor grade and stage, size, depth of invasion, LVSI, and peritoneal cytology. For patients with LVSI, slides were reviewed by 2 pathologists for confirmation of LVSI.

RESULTS

Of 104 patients identified, LVSI was reported in 39 (37.5%) and positive peritoneal cytology in 6 (4.8%). Rates of peritoneal cytology were not significantly different between the 2 groups (odds ratio, 0.55; 95% confidence interval, 0.10-3.17; P=.50). LVSI was reported in significantly fewer robot-assisted hysterectomies than open procedures (odds ratio, 0.39; 95% confidence interval, 0.17-0.92; P=.03). In subgroup analyses restricted to early-stage disease (stage≤II), there was no significant difference in LVSI between open and robot-assisted hysterectomies (odds ratio, 0.64; 95% confidence interval, 0.22-1.85; P=.43).

CONCLUSION

In this retrospective study, we found that use of a uterine manipulator in robot-assisted surgery did not increase the incidence of LVSI.

Gynecologic biopsy for molecular profiling: a review for the interventional radiologist

The interventional radiologist is often asked to obtain multiple biopsies of gynecological malignancies for genetic profiling. This article reviews the current indications for gynecological biopsy as well as how the information gained contributes to a personalized medicine plan for the individual patient. The specific focus of this review is the current knowledge and practice of molecular profiling for gynecological malignancies.

Abstract A63: Tamoxifen effectively suppresses both initiation of intraperitoneal tumors and established ovarian cancer growth in a fluorescent xenograft model

Background: Sixty percent of serous ovarian carcinomas express the estrogen receptor (ER). The antiestrogen (AE) Tamoxifen and aromatase inhibitors (AI) are common therapies for chemoprevention and treatment of ER+ breast cancers, but have not been routinely employed in ovarian cancer. We propose that AE and AI will prevent the initial growth of intraperitoneal (IP) ovarian cancer implants and decrease the volume of established IP implants in a previously established fluorescent mouse xenograft model.

Methods: PEO4 cells were rendered permanently fluorescent with a ZsGreen protein lentivirus. Ovariectomized athymic nude mice (NCI) received IP injections of 107 ER+ PEO4 ovarian cancer cells under an approved animal protocol. Subcutaneous implants of control cellulose (C) , 17 β-estradiol (E), tamoxifen (TAM), anastozole (AN), letrozole (LT) or combinations of drugs [E+TAM, E to TAM, AN +E, AN+TAM] (Sigma) were implanted at the time of IP injections. For experimental arms requiring a second surgery to remove or switch a pellet, disease was allowed to grow for 7 weeks, and then estrogen pellets were removed for estrogen withdrawal (EWD) or removed and substituted with tamoxifen (E to TAM) for an additional 7 weeks. Disease growth was monitored biweekly until 14 weeks by Xenogen IVIS fluorescent imaging, converted to photon flux units, and analyzed using GraphPad software. Uterine weights at necropsy were recorded as an assessment of estrogenic potency. Presence of disease detected by IVIS imaging was confirmed at necropsy.

Results: E promoted growth of IP ER+ PEO4 cells significantly (p&lt;0.05) more than C. EWD for 7 weeks significantly (p&lt;0.05) decreased the volume of IP disease to control baseline. Continuous TAM suppression was not significantly different than C, indicating that the mixed agonist/antagonist TAM is working as an antiestrogen when alone. Substitution of TAM for E after 7 weeks of unopposed E decreased IP disease, while continuous E+TAM for 14 weeks was not different than E alone, indicating that E stimulation predominates. Anastozole alone and letrozole alone did not suppress disease beyond C. AN and LT in combination with E were not effective inhibitors of E stimulation. E+TAM stimulated more disease than AN+TAM indicating that TAM is estrogenic only in the presence of E. The combination of an AE and AI was not more effective than AE alone.

Conclusions: The mixed agonist/antagonist tamoxifen acts as an antagonist when alone, but an agonist in the presence of estrogen in an IP model of ovarian cancer. Antiestrogens such as tamoxifen may be effective adjuvant therapy after removal of endogenous ovarian estrogen in ovarian cancer. Continuous tamoxifen could be investigated as a maintenance therapy after initial ovarian cancer remission through surgery and chemotherapy.

Citation Format: Douglas Hicks, Nicole Manning, Monique A. Spillman. Tamoxifen effectively suppresses both initiation of intraperitoneal tumors and established ovarian cancer growth in a fluorescent xenograft model. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A63.

Abstract A16: CHIP-seq of the estrogen receptor identifies new targetable estrogen regulated pathways in ovarian cancer

Introduction: The estrogen receptor (ER) is found in about 60% of epithelial ovarian cancers; however, ovarian cancers are thought to be less estrogen responsive than breast cancers. Previous data has shown that long term estrogen responsive genes in ovarian cancer overlap with breast cancer genes less than 10% of the time. The question remains whether the estrogen receptor regulates the same signaling pathways in ovarian cancer as in breast cancer. Our hypothesis is that a unique set of estrogen responsive genes and proteins are activated by the ER in epithelial ovarian cancer as compared to breast cancer.

Methods: PEO4 cells were cultured in RPMI 1640-phenol red free media at 107 cells/plate and steroid depleted for four days. PEO4 cells were treated with and without 10-7 M 17 β-estradiol (Sigma) for 45min. Ethanol was used as a vehicle and control. Chromatin immunoprecipitation-sequencing (CHIP-seq) was used to determine the DNA-protein interactions of the estrogen receptor in the ovarian cancer cell line. DNA-protein interactions were crosslinked with formaldehyde, sheared and immunoprecipitated with the antibody ERalpha(HC-20):sc-543 (Santa Cruz). DNA was reversed crosslinked and purified. Biological triplicates were done. Library construction and Illumina HiSeq sequencing was done at the Genomics and Microarray Core at the University of Colorado. Reads were mapped using Novoalign. Identifying regions of enrichment, feature characterization, and motif analysis were performed using Homer (UCSD).

Results: 13,000 genes provided unique sequences by computer analysis in the cells treated with estrogen as compared to the ethanol control. 3,500 were uniquely identified as estrogen responsive genes. 2,800 genes were uniquely identified in control cells. Anticipated internal controls such as C-myc were appropriately identified by this analysis. A known estrogen responsive gene, the prolactin receptor, was identified as an estrogen responsive gene in our early timepoint. MicroRNAs 1260B and 3152, CUGBPa Elav-like family member 2, CSP-beta, STAU2 antisense RNA 1 were also seen in our analysis. Another more frequently identified sequence was CAPRIN1 (cell cycle associated protein 1), that is involved with cell proliferation. Additionally, DNA motif analysis of the ER crosslinked DNA revealed known estrogen responsive elements (EREs) and additionally found other DNA binding motifs such as those for p53, C-MYC, and PAX7. FOXA1, a major ER co-factor in breast cancer, was also enriched in our CHIP-seq analysis.

Conclusion: We have identified a unique set of directly ER modulated genes, microRNAs, and binding sites in an ovarian cancer cell line. These represent potential therapeutic targets for novel antiestrogens in ovarian cancer.

Citation Format: Georgina Cheng, Kian Behbakht, Monique A. Spillman. CHIP-seq of the estrogen receptor identifies new targetable estrogen regulated pathways in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A16.

Type-specific cell line models for type-specific ovarian cancer research

BACKGROUND

OVARIAN CARCINOMAS CONSIST OF AT LEAST FIVE DISTINCT DISEASES: high-grade serous, low-grade serous, clear cell, endometrioid, and mucinous. Biomarker and molecular characterization may represent a more biologically relevant basis for grouping and treating this family of tumors, rather than site of origin. Molecular characteristics have become the new standard for clinical pathology, however development of tailored type-specific therapies is hampered by a failure of basic research to recognize that model systems used to study these diseases must also be stratified. Unrelated model systems do offer value for study of biochemical processes but specific cellular context needs to be applied to assess relevant therapeutic strategies.

METHODS

We have focused on the identification of clear cell carcinoma cell line models. A panel of 32 "ovarian cancer" cell lines has been classified into histotypes using a combination of mutation profiles, IHC mutation-surrogates, and a validated immunohistochemical model. All cell lines were identity verified using STR analysis.

RESULTS

Many described ovarian clear cell lines have characteristic mutations (including ARID1A and PIK3CA) and an overall molecular/immuno-profile typical of primary tumors. Mutations in TP53 were present in the majority of high-grade serous cell lines. Advanced genomic analysis of bona-fide clear cell carcinoma cell lines also support copy number changes in typical biomarkers such at MET and HNF1B and a lack of any recurrent expressed re-arrangements.

CONCLUSIONS

As with primary ovarian tumors, mutation status of cancer genes like ARID1A and TP53 and a general immuno-profile serve well for establishing histotype of ovarian cancer cell We describe specific biomarkers and molecular features to re-classify generic "ovarian carcinoma" cell lines into type specific categories. Our data supports the use of prototype clear cell lines, such as TOV21G and JHOC-5, and questions the use of SKOV3 and A2780 as models of high-grade serous carcinoma.

Copy neutral loss of heterozygosity is more frequent in older ovarian cancer patients

Loss of heterozygosity (LOH) is a common type of genomic alterations in ovarian cancer. Analyzing 74,415 copy neutral LOH events in 513 serous ovarian adenocarcinomas samples from the Cancer Genome Atlas, we report that the frequency of LOH events increases with age. Similar trend is observed for LOH involving chromosome 17, which is frequently implicated in ovarian cancer. The results are consistent when we analyze data from the Boston high-grade serous cancer cohort. We further show that germ line and somatic mutations in BRCA1 (in chromosome 17) and BRCA2 (in chromosome 13) loci are not necessary to establish the pattern. We also report significant age-related changes in expression patterns for several genes in the homologous recombination (HR) pathway, such as BRCA1, RAD50, RAD52, XRCC2, XRCC3, and MRE11A in these patient samples. Furthermore, we develop a metric for pathway-level imbalance, and show that increased imbalance in the HR pathway, i.e., increase in expression of some HR genes and decrease in expression of others, is common and correlates significantly with the frequency of LOH events in the patient samples. Taken together, it is highly likely that aging and deregulation of HR pathway contribute to the increased incidence of copy-neutral LOH in ovarian cancer patients.

Abstract B70: Decreasing ovarian cancer metastases and progression via restoration of microRNAs that target mediators of anoikis- and chemoresistance

Background: Epithelial ovarian cancer (EOC) accounts for the majority of deaths from gynecological malignancies, with a 5-year survival rate for women with advanced stage disease of only 46%. In EOC metastasis primarily occurs by a mechanism termed direct seeding, which involves shedding of tumor cells from the primary site into the peritoneal cavity. To allow survival in suspension before attachment at metastatic sites, ovarian cancer cells must acquire resistance to anoikis, a form of apoptosis initiated by detachment from native extracellular matrix. A targeted therapy that could simultaneously affect multiple factors critical for ovarian cancer progression such as anoikis resistance, chemoresistance and attachment to metastatic sites in the peritoneal cavity, would be a revolutionary breakthrough for this aggressive malignancy. Due to their ability to inhibit multiple targets involved in tumor survival, microRNAs (miRNAs) are attractive therapeutic candidates. We previously demonstrated that miR-200c is downregulated in ovarian cancer cell lines and restoration of miR-200c increased sensitivity to taxanes in vitro, by targeting TUBB3, a known mediator of chemoresistance. We tested the effect of miR-200c restoration in an intraperitoneal xenograft model of human ovarian cancer and observed dramatically decreased tumor formation. Further, even in established tumors, inducible restoration of miR-200c alone and in combination with paclitaxel, resulted in significantly reduced tumor burden.

Hypothesis: Since restoration of miR-200c to multiple anoikis resistant EOC cell lines increased anoikis sensitivity and reduced adherence to biological substrates in vitro, we hypothesized that the decreased intraperitoneal tumor burden observed upon miR-200c restoration resulted from increased anoikis sensitivity.

Methods and results: To elucidate mechanisms of anoikis resistance in ovarian cancer and identify targets involved in the ability of miR-200c to reverse anoikis resistance, we performed gene and miRNA expression profiling of attached Hey ovarian cancer cells as compared to the same cells grown under conditions of forced suspension for 24h. We identified miR-193 as downregulated in anoikis resistant cells in suspension. Among numerous genes predicted as miR-200c and/or miR-193 targets, SCLC7A11 (xCT), which encodes the light chain of the cystine/glutamate antiporter system xc, was increased by 10.7 fold in suspended versus attached cells. The xc- system is involved in glutathione (GSH) synthesis, mediating intracellular defense against oxidative stress. Reactive oxygen species (ROS) increased in anoikis-sensitive (OvCA 433) cells in suspension, but not in anoikis-resistant cells (Hey), suggesting that xCT might protect these cells from ROS-induced cell death. Consistent with this hypothesis, xCT mRNA and protein increased in anoikis resistant EOC cells in suspension, and transient xCT knockdown rendered cells anoikis sensitive. Interestingly, the xCT 3'UTR contains three predicted binding sites for miR-200c and two sites for miR-193b, and restoration of either miRNA blocked the suspension induced-increase in cXT protein, suggesting that both miRNAs target this gene.

Conclusions: Our results indicate that the ability of miR-200c to reduce tumor burden results, at least in part, from its ability to restore anoikis sensitivity by inhibiting a suspension-induced increase in xCT that protects tumor cells from ROS. Thus, miR-200c could be a powerful candidate to block progression of ovarian cancer by enhancing anoikis sensitivity and restoring chemo-sensitivity to already attached tumor.

Citation Format: Diana M. Cittelly, Dawn R. Cochrane, Erin N. Howe, Irina Dimitrova, Miriam D. Post, Broaddus R. Russell, Monique A. Spillman, Jennifer K. Richer. Decreasing ovarian cancer metastases and progression via restoration of microRNAs that target mediators of anoikis- and chemoresistance.. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr B70.

Estrogen switches pure mucinous breast cancer to invasive lobular carcinoma with mucinous features

Mucinous breast cancer (MBC) is mainly a disease of postmenopausal women. Pure MBC is rare and augurs a good prognosis. In contrast, MBC mixed with other histological subtypes of invasive disease loses the more favorable prognosis. Because of the relative rarity of pure MBC, little is known about its cell and tumor biology and relationship to invasive disease of other subtypes. We have now developed a human breast cancer cell line called BCK4, in which we can control the behavior of MBC. BCK4 cells were derived from a patient whose poorly differentiated primary tumor was treated with chemotherapy, radiation and tamoxifen. Malignant cells from a recurrent pleural effusion were xenografted in mammary glands of a nude mouse. Cells from the solid tumor xenograft were propagated in culture to generate the BCK4 cell line. Multiple marker and chromosome analyses demonstrate that BCK4 cells are human, near diploid and luminal, expressing functional estrogen, androgen, and progesterone receptors. When xenografted back into immunocompromised cycling mice, BCK4 cells grow into small pure MBC. However, if mice are supplemented with continuous estradiol, tumors switch to invasive lobular carcinoma (ILC) with mucinous features (mixed MBC), and growth is markedly accelerated. Tamoxifen prevents the expansion of this more invasive component. The unexpected ability of estrogens to convert pure MBC into mixed MBC with ILC may explain the rarity of the pure disease in premenopausal women. These studies show that MBC can be derived from lobular precursors and that BCK4 cells are new, unique models to study the phenotypic plasticity, hormonal regulation, optimal therapeutic interventions, and metastatic patterns of MBC.

Restoration of miR-200c to ovarian cancer reduces tumor burden and increases sensitivity to paclitaxel

A therapeutic intervention that could decrease tumor burden and increase sensitivity to chemotherapy would have a significant impact on the high morbidity rate associated with ovarian cancer. miRNAs have emerged as potential therapeutic candidates due to their ability to downregulate multiple targets involved in tumor progression and chemoresistance. miRNA-200c (miR-200c) is downregulated in ovarian cancer cell lines and stage III ovarian tumors, and low miR-200c correlates with poor prognosis. miR-200c increases sensitivity to taxanes in vitro by targeting class III β-tubulin gene (TUBB3), a tubulin known to mediate chemoresistance. Indeed, we find that patients with tumors having low TUBB3 had significantly prolonged survival (average survival 52.73 ± 4.08 months) as compared with those having high TUBB3 (average survival 42.56 ± 3.19 months). miR-200c also targets TrkB, a mediator of resistance to anoikis. We show that restoration of miR-200c to ovarian cancer cells results in increased anoikis sensitivity and reduced adherence to biologic substrates in vitro. Because both chemo- and anoikis-resistance are critical steps in the progression of ovarian cancer, we sought to determine how restoration of miR-200c affects tumor burden and chemosensitivity in an in vivo preclinical model of ovarian cancer. Restoration of miR-200c in an intraperitoneal xenograft model of human ovarian cancer results in decreased tumor formation and tumor burden. Furthermore, even in established tumors, restoration of miR-200c, alone or in combination with paclitaxel, results in significantly decreased tumor burden. Our study suggests that restoration of miR-200c immediately before cytotoxic chemotherapy may allow for a better response or lower effective dose.

DNA profiling analysis of endometrial and ovarian cell lines reveals misidentification, redundancy and contamination

OBJECTIVES

Cell lines derived from human ovarian and endometrial cancers, and their immortalized non-malignant counterparts, are critical tools to investigate and characterize molecular mechanisms underlying gynecologic tumorigenesis, and facilitate development of novel therapeutics. To determine the extent of misidentification, contamination and redundancy, with evident consequences for the validity of research based upon these models, we undertook a systematic analysis and cataloging of endometrial and ovarian cell lines.

METHODS

Profiling of cell lines by analysis of DNA microsatellite short tandem repeats (STR), p53 nucleotide polymorphisms and microsatellite instability was performed.

RESULTS

Fifty-one ovarian cancer lines were profiled with ten found to be redundant and five (A2008, OV2008, C13, SK-OV-4 and SK-OV-6) identified as cervical cancer cells. Ten endometrial cell lines were analyzed, with RL-92, HEC-1A, HEC-1B, HEC-50, KLE, and AN3CA all exhibiting unique, uncontaminated STR profiles. Multiple variants of Ishikawa and ECC-1 endometrial cancer cell lines were genotyped and analyzed by sequencing of mutations in the p53 gene. The profile of ECC-1 cells did not match the EnCa-101 tumor, from which it was reportedly derived, and all ECC-1 isolates were genotyped as Ishikawa cells, MCF-7 breast cancer cells, or a combination thereof. Two normal, immortalized endometrial epithelial cell lines, HES cells and the hTERT-EEC line, were identified as HeLa cervical carcinoma and MCF-7 breast cancer cells, respectively.

CONCLUSIONS

Results demonstrate significant misidentification, duplication, and loss of integrity of endometrial and ovarian cancer cell lines. Authentication by STR DNA profiling is a simple and economical method to verify and validate studies undertaken with these models.

Abstract B33: PTTG1 expression predicts sensitivity to the Src inhibitor Saracatinib in ovarian cancer cell lines

Background: Increasing numbers of tyrosine kinases have been investigated as potential targets in molecular cancer therapy. Src, a nonreceptor tyrosine kinase, is one such attractive target since it is highly expressed in many malignancies including ovarian cancer, and plays a key role in tumor progression and metastasis. In clinical trials, however, Src kinase inhibitors exhibited limited activity in unselected patients. To understand the detailed mechanisms of Src inhibition, we developed a gene expression profile using a panel of ovarian cancer cell lines with known IC50 values to the Src inhibitor saracatinib to identify genes likely to associate with sensitivity/resistance to saracatinib. Among the genes identified, we sought to find and characterize a gene that could be predictive of response to saracatinib.

Methods: We utilized a Src kinase inihibitor, saracatinib (AZD0530), which was kindly provided by AstraZeneca. We performed MTT based cell proliferation assays for 18 ovarian cancer cell lines to determine their sensitivities to saracatinib, and classified them as either sensitive or resistant according to their IC50 data. The mean of log10(IC50) across 18 lines was used as a cutoff value. A gene expression profile associated with the Src inhibitor sensitivity was developed by processing extracted RNA from those cell lines and running Affymetrix Human Gene 1.0 ST arrays. Data normalization and statistical analysis were conducted using Partek Genomics Suite software. To explore the expression changes in protein level for the selected gene before and after treatment with saracatinib, we performed western blots for several drug-sensitive and resistant cell lines. Cells were treated for 24 hours with physiological concentrations of saracatinib.

Results: Out of eighteen ovarian cancer cell lines, 11 and 7 cell lines were categorized into sensitive and resistant groups respectively based on the results from cell proliferation assays. The mean of log10(IC50) was 1.51 μM, which was used as cutoff value to define as sensitive or resistant. Statistical analysis for the gene expression profile detected seven differentially expressed genes between the two groups (p &lt; 2.31×10−5, two sample t-test for sensitive group versus resistant group and false discovery rate of &lt; 0.05). Among them, we focused on pituitary tumor transforming gene 1 (PTTG1; securin) since it is involved in a variety of cancer-related processes such as cell transformation, mitotic regulation and angiogenesis. In addition, previous studies have shown higher expressions of PTTG1 gene in many cancers, including ovarian cancer, when compared with normal tissues. We found that PTTG1 gene expression levels were higher in resistant lines (mean resistant/sensitive ratio = 2.0, p-value = 5.74×10−6). Interestingly, our western blot results demonstrated that in sensitive cell lines, the protein level of PTTG1 was significantly reduced by treatment with saracatinib, but no reduction was seen in the resistant lines. These results indicate that enhanced and preserved PTTG1 expression correlates with resistance to Src inhibition. The ability of this gene to work as a predictive biomarker for saracatinib sensitivity should be further investigated in practical tumor specimens.

Conclusions: Highly expressed PTTG1 gene correlates with resistance to Src inhibition. PTTG1 could be a predictive biomarker for sensitivity to Src kinase inhibitor.

Specificity and prognostic validation of a polyclonal antibody to detect Six1 homeoprotein in ovarian cancer

OBJECTIVE

The presence of Six1 mRNA gene portends a poor prognosis in ovarian cancer. We describe validation of a Six1 specific antibody and evaluate its association with tumorigenicity and prognosis in ovarian cancer.

METHODS

A Six1 antibody (Six1cTerm) was raised to residues downstream of the Six1 homeodomain, representing its unique C-terminus as compared to other Six family members. Cells were transfected with Six1-Six6 and Western blot was performed to demonstrate Six1 specificity. Ovarian cancer cell lines were analyzed for Six1 mRNA and Six1cTerm and tumorigenicity was evaluated. Ovarian cancer tissue microarrays (OTMA) were analyzed for Six1cTerm by immunohistochemistry and scored by two blinded observers. The metastatic tumors of 15 stage IIIC high grade serous ovarian cancers were analyzed with Six1 mRNA and Six1cTerm and expression was compared to clinical factors and survival.

RESULTS

The Six1cTerm antibody is specific for Six1. Cell line tumorigenicity in SCID mice correlates with Six1 levels both by mRNA(p=0.001, Mann-Whitney U test) and by protein (presence vs. absence, p=0.05 Fischer's Exact test). Six1 protein was present in up to 54% of OTMA specimens. Six1 protein expression in omental/peritoneal metastases correlated with worsened survival in a sample (n=15) of high grade serous stage IIIC ovarian cancers (p=0.001).

CONCLUSIONS

The Six1cTerm antibody is specific and able to detect Six1 in cell lines and tumor tissue. Six1 protein detection is common in ovarian cancer and is associated with tumorigenicity and poor prognosis in this group of patient samples. Six1cTerm antibody should be further validated as prognostic tool.

Gab2 regulates the migratory behaviors and E-cadherin expression via activation of the PI3K pathway in ovarian cancer cells

Ovarian cancer, the most deadly gynecologic malignancy, is often diagnosed late and at the advanced stage when the cancer cells have already migrated and invaded into other tissues and organs. Better understanding of the mechanism of metastasis in ovarian cancer cells is essential to the design of effective therapy. In this study, we investigated the function of scaffolding adaptor protein Gab2 in ovarian cancer cells. Gab2 is found to be overexpressed in a subset of ovarian tumors and cancer cell lines. Gab2 expression mainly regulates the migratory behaviors of ovarian cancer cells. Overexpression of Gab2 promotes the migration and invasion, and down-regulates E-cadherin expression in ovarian cancer cells with low-Gab2 expression. Conversely, knockdown of Gab2 expression inhibits the migration and invasion, and promotes E-cadherin expression in ovarian cancer cells with high-Gab2 expression. By expressing Gab2 wild type and Gab2 mutants that are defective in activation the PI3K and Shp2-Erk pathways, we find that Gab2 inhibits E-cadherin expression and enhances the expression of Zeb1, a transcription factor involved in epithelial-to-mesenchymal transition (EMT), and cell migration and invasion through the activation of the PI3K pathway. Knockdown of Zeb1 expression blocks Gab2-induced suppression of E-cadherin expression and increase in cell invasion. LY294002 and GDC-0941, inhibitors of PI3K, or Rapamycin, an inhibitor of PI3K downstream target mTOR, can reverse the effects of Gab2 on migration and invasion. Overall, our studies reveal that Gab2 overexpression, via activation of the PI3K-Zeb1 pathway, promotes characteristics of EMT in ovarian cancer cells.

Unliganded progesterone receptors attenuate taxane-induced breast cancer cell death by modulating the spindle assembly checkpoint

Whether the presence of steroid receptors in luminal breast cancers renders them resistant to taxanes remains uncertain. Here we assess the role of progesterone receptors (PR) on taxane-induced cell death. We previously showed that estrogen receptor (ER)-positive human breast cancer cells that inducibly express PR-A or PR-B isoforms were protected from taxane-stimulated apoptosis when compared to the identical cells lacking PR. Surprisingly, PR-dependent protection occurred in the absence of progesterone, demonstrating that the unliganded receptors were biologically active. The present studies demonstrate that unliganded PR, focused on PR-A, protect breast cancer cells from taxane-stimulated apoptosis. The studies identify genes regulated by taxanes in isogenic ER-positive cells that either lack or express PR-A. We show that unliganded PR-A alters the gene expression pattern controlled by taxanes, especially multiple genes involved in the spindle assembly checkpoint, a group of proteins that insure proper attachment of microtubules to kinetochores during mitosis. Importantly, taxanes and unliganded PR regulate many of these genes in opposite directions. As a result, mitotic slippage is exacerbated by the presence of PR, leading to an increase in the number of multinucleated cells both in vitro and in xenograft tumors. We describe a simple new assay for assessing multinucleation in paraffin sections. We speculate that rather than inducing cell death, unliganded PR exploits multinucleation to promote cell survival from taxane therapy. This can be prevented with antiprogestin.

Large cell neuroendocrine carcinoma of the cervix: prognostic factors and survival advantage with platinum chemotherapy

OBJECTIVE

Large cell neuroendocrine carcinoma of the cervix (LCNEC) is a rare cervical neoplasm associated with poor survival. Our objective was to identify treatments associated with improved survival.

METHODS

Relevant data were abstracted from an English literature MEDLINE search, SEER database, and a patient treated at our institution. Multivariate analysis was performed by generating Cox proportional hazard ratios.

RESULTS

We identified 62 patients with LCNEC: 49 cases from the English literature, 12 patients in the SEER database and our patient. Out of the 62 women, median age was 37 (range, 21-75). FIGO stage was as follows: 58% had stage I disease, 16% had stage II, 2% had stage III, 8% had stage IV disease and 16% had no stage documented. Of all patients, 73% underwent primary surgery, 4.7% underwent primary radiation, 4.7% underwent chemotherapy, 8% had chemoradiation, and 9.6% had no primary treatment. Of all patients, 58% died of disease, 26% had no evidence of disease, 3% were alive with disease, and 13% had no survival data. The overall median survival was 16.5 months (0.5-151 months). Median overall survival for stage I, II, III, and IV cancers was 19, 17, 3, and 1.5 months, respectively. In a multivariate analysis, earlier stage (p<0.00001) and the addition of chemotherapy (p=0.04) were associated with improved survival. Both platinum agents (p=0.034) and platinum and etoposide together (p=0.027) were associated with improved survival.

CONCLUSIONS

Perioperative chemotherapy, in particular platinum with or without etoposide, improves survival in the rare LCNEC.

Tissue-specific pathways for estrogen regulation of ovarian cancer growth and metastasis

Menopausal estrogen (E2) replacement therapy increases the risk of estrogen receptor (ER)-positive epithelial ovarian cancers (EOC). Whether E2 is tumorigenic or promotes expansion of undiagnosed preexisting disease is unknown. To determine E2 effects on tumor promotion, we developed an intraperitoneal mouse xenograft model using ZsGreen fluorescent ER(-) 2008 and ER(+) PEO4 human EOC cells. Tumor growth was quantified by in vivo fluorescent imaging. In ER(+) tumors, E2 significantly increased size, induced progesterone receptors, and promoted lymph node metastasis, confirming that ERs are functional and foster aggressiveness. Laser-captured human EOC cells from ER(-) and ER(+) xenografted tumors were profiled for expression of E2-regulated genes. Three classes of E2-regulated EOC genes were defined, but <10% were shared with E2-regulated breast cancer genes. Because breast cancer selective ER modulators (SERM) are therapeutically ineffective in EOC, we suggest that our EOC-specific E2-regulated genes can assist pharmacologic discovery of ovarian-targeted SERM.

Progesterone receptor action: translating studies in breast cancer models to clinical insights

Progesterone receptors (PR) are useful prognostic indicators of breast cancers likely to respond to anti-estrogen receptor (ER) therapies. However, the role of progesterone, therapeutic progestins, or unliganded or liganded PRin breast cancer development or progression remains controversial. PR are ligand-activated transcription factors that act in concert with intracellular signaling pathways as "sensors" of multiple growth factor inputs to hormonally regulated tissues, such as the breast. The recently defined induction of rapid signaling events upon progestin-binding to PR-B provides a means to ensure that receptors and coregulators are appropriately phosphorylated as part of optimal transcription complexes. PR-activated kinase cascades may provide additional avenues for progestin-regulated gene expression independent of PR nuclear action. Herein, we present an overview ofprogesterone/PR and signaling cross-talk in breast cancer models and discuss the potential significance ofprogestin/PR action in breast cancer biology using examples from both in vitro and in vivo models, as well as limited clinical data. Kinases are emerging as key mediators of PR action. Cross-talk between PR and membrane-initiated signaling events suggests a mechanism for coordinated regulation ofgene subsets by mitogenic stimuli in hormonally responsive normal tissues. Dysregulation of this cross-talk mechanism may contribute to breast cancer biology; further studies are needed to address the potential for targeting PR in addition to ER and selected protein kinases as part of more effective breast cancer therapies.

Regulation of the metastasis suppressor gene MKK4 in ovarian cancer

OBJECTIVES

MKK4 is a metastasis suppressor that is downregulated in some ovarian cancers. We sought to investigate whether promoter methylation, loss of heterozygosity, or changes in phosphorylation are involved in MKK4 dysregulation during ovarian carcinogenesis.

METHODS

Bisulfite sequencing was used to determine MKK4 promoter methylation. PCR analysis of tumor/normal DNA was performed to determine LOH at the MKK4 locus. Normal human ovarian surface epithelium (HOSE) and SKOV-3 cells were serum starved and treated with EGF, TGFbeta, or wortmannin. Western blotting was performed using antibodies that detect total and phosphorylated MKK4.

RESULTS

No MKK4 promoter hypermethylation was detected in 21 ovarian cancers. LOH was detected at the MKK4 intragenic marker D17S969 in 35% of cases and at D17S1303 in 20%. MKK4 protein was detected in 97% of ovarian tumors. The inactivated phosphoserine 80 (ser-80) form comprised 62% of phosphorylated MKK4 protein in ovarian tumors. Treatment of HOSE or SKOV-3 cells with EGF induced a 1.7- to 4.2-fold increase in phosphorylation of ser-80 MKK4 without altering total MKK4 protein. TGFbeta increased MKK4 ser-80 phosphorylation by 5.4-fold above baseline. The PI3K/Akt pathway inhibitor wortmannin decreased the amount of ser-80 MKK4 by 50%, and inhibited EGF stimulation of MKK4 ser-80 phosphorylation by 60%.

CONCLUSIONS

LOH of MKK4 occurs in some ovarian cancers, but without loss of MKK4 protein. MKK4 expression does not appear to be downregulated by promoter methylation. Peptide growth factors induce MKK4 ser-80 phosphorylation, which downregulates its activity. PI3K/Akt pathway inhibitors can partially block ser-80 phosphorylation and this may have therapeutic implications.

Clinical trials of xenotransplantation: waiver of the right to withdraw from a clinical trial should be required

Xenotransplantation pits clinical research ethics against public health needs because recipients must undergo long-term, perhaps life-long, surveillance for infectious diseases. This surveillance requirement is effectively an abrogation of the right to withdraw from a clinical trial. Ulysses contracts, which are advance directives for future care, may be an ethical mechanism by which to balance public health needs against limitation of individual rights.

Frequent IGF2/H19 domain epigenetic alterations and elevated IGF2 expression in epithelial ovarian cancer

Overexpression of the imprinted insulin-like growth factor-II (IGF2) is a prominent characteristic of gynecologic malignancies. The purpose of this study was to determine whether IGF2 loss of imprinting (LOI), aberrant H19 expression, and/or epigenetic deregulation of the IGF2/H19 imprinted domain contributes to elevated IGF2 expression in serous epithelial ovarian tumors. IGF2 LOI was observed in 5 of 23 informative serous epithelial ovarian cancers, but this did not correlate with elevated expression of IGF2 H19 RNA expression levels were also found not to correlate with IGF2 transcript levels. However, we identified positive correlations between elevated IGF2 expression and hypermethylation of CCCTC transcription factor binding sites 1 and 6 at the H19 proximal imprint center (P = 0.05 and 0.02, respectively). Hypermethylation of CCCTC transcription factor sites 1 and 6 was observed more frequently in cancer DNA compared with lymphocyte DNA obtained from women without malignancy (P < 0.0001 for both sites 1 and 6). Ovarian cancers were also more likely to exhibit maternal allele-specific hypomethylation upstream of the imprinted IGF2 promoters when compared with normal lymphocyte DNA (P = 0.004). This is the same region shown previously to be hypomethylated in colon cancers with IGF2 LOI, but this was not associated with LOI in ovarian cancers. Elevated IGF2 expression is a frequent event in serous ovarian cancer and this occurs in the absence of IGF2 LOI. These data indicate that the epigenetic changes observed in these cancers at the imprint center may contribute to IGF2 overexpression in a novel mechanistic manner.

Transforming growth factor beta receptor I polyalanine repeat polymorphism does not increase ovarian cancer risk

OBJECTIVES

It has been suggested that the 6A allele of the type I TGFbeta receptor (TGFbetaR1) polyalanine repeat tract polymorphism may increase susceptibility to various types of cancer including ovarian cancer.

METHODS

The TGFbetaR1 polyalanine polymorphism was genotyped in 588 ovarian cancer cases and 614 controls from a population-based case-control study in North Carolina.

RESULTS

Significant racial differences in the frequency of the 6A allele were observed between Caucasian (10.7%) and African-American (2.4%) controls (P < 0.001). One or two copies of the 6A allele of the TGFbetaR1 polyalanine polymorphism was carried by 18% of all controls and 19% of cases, and there was no association with ovarian cancer risk (OR = 1.07, 95% CI 0.80-1.44). The odds ratio for 6A homozygotes was 1.81 (95% CI 0.655.06), but these comprised only 0.98% of controls and 1.70% of cases.

CONCLUSIONS

The 6A allele of the TGFbetaR1 polyalanine polymorphism does not appear to increase ovarian cancer risk. Larger studies would be needed to exclude the possibility that the small fraction of individuals who are 6A homozygotes have an increased risk of ovarian or other cancers.

Managing familial risk in genetic testing

Increasing numbers of people are seeking genetic testing and uncovering information that directly concerns their biological relatives as well as themselves. This familial quality of genetic information raises ethical quandaries for physicians, particularly related to their duty of confidentiality. In this article, the American Medical Association's Council on Ethical and Judicial Affairs examines the informed consent process in the specific context of genetic testing, giving particular consideration to the handling of information that has consequences for biological relatives. Furthermore, it addresses the question of whether physicians' obligation to warn biological relatives ever should override the obligation to protect patient confidentiality.

Managing conflicts of interest in the conduct of clinical trials

The interaction between medical research and for-profit corporations is not new, but it has expanded considerably in recent years. Some of the recent trends may accelerate the research process, particularly when large clinical trials are required. However, a renewed commitment to the application of high ethical standards is essential to ensure that societal trust in research is not eroded, subjects enrolled in trials do not become merely a means to an end, and medical research is efficiently translated into clinical advances that will benefit future patients. This article focuses on the analysis of conflicts of interest in the conduct of clinical trials in both academic and community-based settings. Specifically, it discusses how the roles of research scientists and clinical practitioners differ and the importance of ensuring that participants' consent to enroll in clinical trials is not the result of confusion about the goals of an experimental treatment that may resemble clinical care. The article also discusses the potential conflicts of interest that can arise when clinicians stand to gain from enrolling their own patients as subjects in clinical trials and examines various instances in which disclosure of information regarding funding and compensation may serve to minimize such conflicts. This article emphasizes that to preserve the integrity of research and to protect the welfare of human subjects who enroll in trials, physicians should have adequate training in the conduct of research and be familiar with the ethics of research. When a physician has treated or continues to treat a patient who is eligible to enroll as a subject in a clinical trial conducted by the same physician, someone other than the treating physician should obtain the participant's informed consent. Finally, the article addresses disclosure of financial incentives and related funding issues.

Characterization of a breast cancer cell line derived from a germ-line BRCA1 mutation carrier

A tumor cell line, HCC1937, was established from a primary breast carcinoma from a 24-year-old patient with a germ-line BRCA1 mutation. A corresponding B-lymphoblastoid cell line was established from the patient's peripheral blood lymphocytes. BRCA1 analysis revealed that the tumor cell line is homozygous for the BRCA1 5382insC mutation, whereas the patient's lymphocyte DNA is heterozygous for the same mutation, as are at least two other family members' lymphocyte DNA. The tumor cell line is marked by multiple additional genetic changes including a high degree of aneuploidy, an acquired mutation of TP53 with wild-type allele loss, an acquired homozygous deletion of the PTEN gene, and loss of heterozygosity at multiple loci known to be involved in the pathogenesis of breast cancer. Comparison of the primary tumor with the cell line revealed the same BRCA1 mutation and an identical pattern of allele loss at multiple loci, indicating that the cell line had maintained many of the properties of the original tumor. This breast tumor-derived cell line may provide a useful model system for the study of familial breast cancer pathogenesis and for elucidating BRCA1 function and localization.

Mutations in the BRCA1-associated RING domain (BARD1) gene in primary breast, ovarian and uterine cancers

Germline alterations of BRCA1 result in susceptibility to breast and ovarian cancer. The protein encoded by BRCA1 interacts in vivo with the BRCA1-associated RING domain (BARD1) protein. Accordingly, BARD1 is likely to be a critical factor in BRCA1-mediated tumor suppression and may also serve as a target for tumorigenic lesions in some human cancers. We have now determined the genomic structure of BARD1 and performed a mutational analysis of 58 ovarian tumors, 50 breast tumors and 60 uterine tumors. Seven polymorphisms were detected within the 2.34 kb coding sequence of BARD1 . Somatically acquired missense mutations were observed in one breast carcinoma and one endometrial tumor; in at least one of these cases, tumor formation was accompanied by loss of the wild-type BARD1 allele, following the paradigm for known tumor suppressor genes. In addition, a germline alteration of BARD1 was identified in a clear cell ovarian tumor (Gln564His); again, loss of the wild-type BARD1 allele was observed in the malignant cells of this patient. The Gln564His patient was also diagnosed with two other primary cancers: a synchronous lobular breast carcinoma and a stage IA clear cell endometrioid cancer confined to an endometrial polyp 6 years earlier. These findings suggest an occasional role for BARD1 mutations in the development of sporadic and hereditary tumors.

Identification of a RING protein that can interact in vivo with the BRCA1 gene product

The hereditary breast and ovarian cancer gene, BRCA1, encodes a large polypeptide that contains the cysteine-rich RING motif, a zinc-binding domain found in a variety of regulatory proteins. Here we describe a novel protein that interacts in vivo with the N-terminal region of BRCA1. This BRCA1-associated RING domain (BARD1) protein contains an N-terminal RING motif, three tandem ankyrin repeats, and a C-terminal sequence with significant homology to the phylogenetically conserved BRCT domains that lie near the C terminus of BRCA1. The BARD1/BRCA1 interaction is disrupted by BRCA1 missense mutations that segregate with breast cancer susceptibility, indicating that BARD1 may be involved in mediating tumour suppression by BRCA1.

BRCA1 and BRCA2 mRNA levels are coordinately elevated in human breast cancer cells in response to estrogen

The steady state levels of BRCA1 and BRCA2 mRNAs were shown to be coordinately elevated by the steroid hormone estrogen but not progesterone in the human breast cancer cell lines BT-483 and MCF-7. Two different antiestrogens, trans 4'-hydroxytamoxifen and ICI 182,780, blocked the elevation of BRCA1 and BRCA2 mRNA levels, confirming that the effect was mediated through the estrogen receptor. In BT-483 cells, BRCA1 and BRCA2 mRNA levels were both elevated 18 to 24 h after estrogen stimulation, suggesting that the effect of estrogen was indirect. Cycloheximide blocked the estrogen effect implying that estrogen induces synthesis of an unidentified estrogen-responsive protein(s) that then result in the elevation of BRCA1 and BRCA2 mRNAs.