17β-estradiol promotes extracellular vesicle release and selective miRNA loading in ERα-positive breast cancer

The causes and consequences of abnormal biogenesis of extracellular vesicles (EVs) are not yet well understood in malignancies, including in breast cancers (BCs). Given the hormonal signaling dependence of estrogen receptor-positive (ER+) BC, we hypothesized that 17β-estradiol (estrogen) might influence EV production and microRNA (miRNA) loading. We report that physiological doses of 17β-estradiol promote EV secretion specifically from ER+ BC cells via inhibition of miR-149-5p, hindering its regulatory activity on SP1, a transcription factor that regulates the EV biogenesis factor nSMase2. Additionally, miR-149-5p downregulation promotes hnRNPA1 expression, responsible for the loading of let-7's miRNAs into EVs. In multiple patient cohorts, we observed increased levels of let-7a-5p and let-7d-5p in EVs derived from the blood of premenopausal ER+ BC patients, and elevated EV levels in patients with high BMI, both conditions associated with higher levels of 17β-estradiol. In brief, we identified a unique estrogen-driven mechanism by which ER+ BC cells eliminate tumor suppressor miRNAs in EVs, with effects on modulating tumor-associated macrophages in the microenvironment.

Correlation of circulating or disseminated tumor cells with the Oncotype DX Recurrence Score

PURPOSE

New biomarkers are emerging to predict recurrence risk in women with early-stage breast cancer. High Oncotype DX Recurrence Score® (RS) is associated with worse disease-free and overall survival. Similarly, circulating tumor cells (CTCs, blood) and disseminated tumor cells (DTCs, bone marrow) have prognostic value in breast cancer. We investigated the association between high RS and CTCs or DTCs.

METHODS

Using a prospective database, we evaluated patients with hormone receptor-positive/HER2-negative, node-negative invasive breast cancer from 1/2005 to 1/2017. RS was classified using TAILORx study cutoff points: low (< 11), intermediate (11-25), and high (> 25). CTCs were assessed using CellSearch® and DTCs using cytospin specimens of bone marrow aspirates. Positive result was defined as one or more CTCs or DTCs identified. Chi-square analyses were utilized to evaluate the relationship between RS and CTCs or DTCs.

RESULTS

233 patients were identified from a prospective database, of which 96 had RS results. Of these patients, 88 had CTC results and 58 had DTC results. CTCs were detected in 17/88 (19%) patients, while DTCs were detected in 20/58 (34%). Patients with high RS were not more likely to have CTCs (18%) compared to patients with low/intermediate RS (20%; p = 0.919). Similarly, high RS was not associated with DTC detection, with DTCs present in 40% of patients with high RS versus 33% with low/intermediate RS (p = 0.687). In the subgroup of patients ≤ 50 years, no associations were found between high RS and CTCs (p = 0.383) or DTCs (p = 0.234).

CONCLUSIONS

High Oncotype DX RS did not correlate with CTCs in blood or DTCs in bone marrow in our study.

Circulating Tumor Cells and Early Relapse in Node-positive Melanoma

PURPOSE

There is a need for sensitive, reproducible biomarkers for patients with stage III melanoma to guide clinical decision making. Circulating tumor cells (CTCs) can be detected in patients with melanoma; however, there are limited data regarding their significance in stage III disease. The aim of this study was to determine whether CTCs are associated with early relapse in stage III melanoma.

EXPERIMENTAL DESIGN

We prospectively assessed CTCs at first presentation in clinic (baseline) for 243 patients with stage III melanoma. CTCs were measured using the CellSearch System. Relapse-free survival (RFS) was compared between patients with one or more baseline CTC versus those with no CTCs. Log-rank test and Cox regression analysis were applied to establish associations of CTCs with RFS.

RESULTS

At least one baseline CTC was identified in 90 of 243 (37%) patients. Forty-five (19%), 67 (28%), 118 (49%), and 13 (5%) patients were stage IIIA, IIIB, IIIC, or IIID, respectively. CTC detection was not associated with substage, or primary tumor characteristics. Multivariable analysis demonstrated that the detection of ≥1 baseline CTC was significantly associated with decreased 6-month RFS [log-rank, P < 0.0001; HR, 3.62, 95% confidence interval (CI), 1.78-7.36; P < 0.0001] and 54-month RFS (log-rank, P = 0.01; HR, 1.69; 95% CI, 1.13-2.54; P = 0.01).

CONCLUSIONS

≥1 CTC was independently associated with melanoma relapse, suggesting that CTC assessment may be useful to identify patients at risk for relapse who could derive benefit from adjuvant therapy.

Circulating Tumor Cells in Breast Cancer Patients Treated by Neoadjuvant Chemotherapy: A Meta-analysis

Background

We conducted a meta-analysis in nonmetastatic breast cancer patients treated by neoadjuvant chemotherapy (NCT) to assess the clinical validity of circulating tumor cell (CTC) detection as a prognostic marker.

Methods

We collected individual patient data from 21 studies in which CTC detection by CellSearch was performed in early breast cancer patients treated with NCT. The primary end point was overall survival, analyzed according to CTC detection, using Cox regression models stratified by study. Secondary end points included distant disease-free survival, locoregional relapse-free interval, and pathological complete response. All statistical tests were two-sided.

Results

Data from patients were collected before NCT (n = 1574) and before surgery (n = 1200). CTC detection revealed one or more CTCs in 25.2% of patients before NCT; this was associated with tumor size (P < .001). The number of CTCs detected had a detrimental and decremental impact on overall survival (P < .001), distant disease-free survival (P < .001), and locoregional relapse-free interval (P < .001), but not on pathological complete response. Patients with one, two, three to four, and five or more CTCs before NCT displayed hazard ratios of death of 1.09 (95% confidence interval [CI] = 0.65 to 1.69), 2.63 (95% CI = 1.42 to 4.54), 3.83 (95% CI = 2.08 to 6.66), and 6.25 (95% CI = 4.34 to 9.09), respectively. In 861 patients with full data available, adding CTC detection before NCT increased the prognostic ability of multivariable prognostic models for overall survival (P < .001), distant disease-free survival (P < .001), and locoregional relapse-free interval (P = .008).

Conclusions

CTC count is an independent and quantitative prognostic factor in early breast cancer patients treated by NCT. It complements current prognostic models based on tumor characteristics and response to therapy.

Abstract 456: Circulating tumor cells and cfDNA changes during radiotherapy in patients with head and neck cancer

Introduction: Head and neck cancer treatment response relies heavily on macroscopic clinical findings. Blood monitoring of circulating markers such as circulating tumor cell (CTC) and cell-free DNA (cfDNA) during treatment may improve earlier detection of responders versus non-responders during definitive radiotherapy. Our work prospectively describes the changes in CTC and cfDNA enumeration during definitive radiotherapy.

Methods: Patients with mucosal head and neck squamous cell carcinoma and intact gross tumor were eligible for the prospective IRB-approved PREDICT-HN study. Blood samples were collected pre-treatment, after first treatment, weekly, and post-treatment (CellSave and EDTA tubes). CTC was enumerated using the FDA-approved CellSearch (Menarini Silicon Biosystems) system. Filtered plasma were collected from the EDTA tubes and stored at -80C. cfNA from pre-, mid- and post-treatment timepoints were isolated from the filtered plasma using the MagMAX Nucleic Acid Isolation Kit (Thermo Fisher Scientific) and cfDNA were quantified with Qubit high sensitivity dsDNA assay (Invitrogen).

Results: 339 blood samples were collected from 45 patients; 137 had detectable CTC. Eight patients had detectable CTCs (1-3/7.5ml blood) in pre-treatment samples. After 1 fraction of radiotherapy, 16 patients had CTCs detected with 12 who had no CTC detected pre-treatment. 19 (42%) patients had detectable CTC in week 6 of treatment. All patients had detectable CTC at some point during radiotherapy except for one patient who had no CTC detected pre, during and post-treatment. There was no correlation between cancer stage, nodal status and gross tumor volume with detection of CTC. Overall circulating cfDNA levels increased during treatment, with their highest level in the final week of treatment similar to when the majority of CTC were detectable in patients, and lowest at the post-treatment time-point.

Conclusions: Our interim results showed, for the 1sttime, to our knowledge, that CTCs can be detected during radiotherapy of head and neck cancer, suggesting mobilization into peripheral circulation during treatment, with as-yet-unknown viability. cfDNA kinetics during treatment correlated with CTC release, may indicate apoptotic change during radiotherapy. Combined cfDNA-CTC as an early marker of treatment response should be investigated.

Citation Format: Sweet Ping Ng, Carolyn S. Hall, Salyna Meas, Vanessa N. Sarli, Houda Bahig, Baher Elgohari, Amy Moreno, Heath D. Skinner, Adam S. Garden, David I. Rosenthal, William H. Morrison, Jack Phan, G Brandon Gunn, Steven J. Frank, Clifton D. Fuller, Anthony Lucci. Circulating tumor cells and cfDNA changes during radiotherapy in patients with head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 456.

Pathologic complete response and serial circulating tumor cell monitoring during neoadjuvant therapy in nonmetastatic triple-negative breast cancer patients

e12111

Background: ARTEMIS (A Randomized, TNBC Enrolling trial to confirm Molecular profiling Improves Survival) is a randomized trial to determine if precision guided neoadjuvant chemotherapy (NAC) influences rates of pathologic complete response in the breast and axillary nodes (pCR). We hypothesized that blood circulating tumor cell (CTC) identification before and/or after NAC (just before surgery) would be associated with pCR in non-metastatic TNBC patients. Methods: Blood was assessed for CTCs at baseline (pre-NAC) and after NAC (post-NAC), as part of an IRB approved study, ARTEMIS (2014 – 0185/PA15-1050). CTCs (per 7.5 ml blood) were identified using the Cell Search System (Menarini Silicon Biosystems). Samples > one cell having morphologic criteria for malignancy were deemed CTC+. Fisher exact test was used to evaluate associations between CTC detection and clinicopathologic characteristics, and Chi2 test was used to analyze associations between CTC detection pre- and post- NAC, and pCR. Results: Fifty-nine patients had pre-NAC and 43 patients had post-NAC CTC assessments. One or more CTC was detected in 13/59 (22%) patients pre-NAC and in 16/43 (37%) of post NAC samples. CTC detection was not associated with patient stage, tumor androgen receptor expression, vimentin expression, Ki-67 staining, or tumor-infiltrating lymphocyte levels. Pre-NAC CTC detection was not (chi2 P = 0.98), but post-NAC (chi2 P = 0.0017) CTC identification was negatively associated with pCR. Conclusions: CTC detection post-NAC was negatively associated with pCR in non-metastatic TNBC patients. These findings warrant larger studies studying serial CTC detection throughout treatment to assess response to NAC.

Tumor volume, circulating tumor cells, and cfDNA changes during radiotherapy in patients with head and neck cancer

6062

Background: Head and neck (HN) cancer treatment response relies heavily on macroscopic clinical findings. Monitoring of circulating markers during treatment may improve detection of responders versus non-responders during radiotherapy (RT). Our work prospectively describes the changes in gross tumor volume (GTV), circulating tumor cell (CTC), and cell-free DNA (cfDNA) enumeration during RT. Methods: Patients with intact HN squamous cell carcinoma were enrolled in a prospective IRB-approved study. Pre-, after first RT, weekly in-, and post-RT blood samples were collected. Serial pre-, weekly in-, and post-RT magnetic resonance imaging (MRI) was obtained. Serial GTV measurements were recorded. CTC was enumerated using the FDA-approved CellSearch (Menarini Silicon Biosystems) system. Plasma were collected and cfNA from pre-, mid- and post-RT timepoints were isolated using the MagMAX Nucleic Acid Isolation Kit (Thermo Fisher Scientific), and cfDNA were quantified with Qubit high sensitivity dsDNA assay (Invitrogen). Results: 40 patients were eligible for analysis. Median age was 60 years and 36 were males. The median pre-RT GTV was 14.1cc (range 1.3 – 44.9cc). There was a median reduction of 81% in GTV by week 4 (p < 0.0001). Of the 341 samples analyzed for CTC, 146 (43%) had detectable CTC. 7 patients had detectable pre-RT CTCs (1-3/7.5ml blood). There was no correlation between cancer stage, nodal status, and GTV with detection of CTC. After 1 fraction of RT, 14 patients had CTCs detected, including 11 who had no CTC detected prior. All patients had CTC detected at some point during RT except for 2 patients who had none. In week 4, with significant reduction in GTV, 25 (63%) had detectable CTC. 16 and 11 patients had detectable CTC in final week and post-RT timepoints. The cfDNA levels increased during RT, with its highest level in the final week of RT and lowest at post-RT time-point, inversely correlated with GTV. Conclusions: Our study showed that CTCs can be detected during RT, suggesting mobilization into peripheral circulation during RT with unknown viability. cfDNA kinetics during RT correlated with CTC release, and may indicate apoptotic change during RT. Combined cfDNA-CTC as an early marker of treatment response should be investigated further.

Circulating cell-free DNA (ctDNA) assessments before, during, and after neoadjuvant therapy (NAC) in nonmetastatic inflammatory breast cancer (IBC)

e12113

Background: : IBC is a rare and aggressive subtype of breast cancer. A significant number of IBC patients who achieve pathologic complete response (no residual tumor in breast and axillary nodes, pCR) relapse after NAC. We hypothesized that circulating cell-free DNA (ctDNA) identified in blood before, during, and after NAC would identify novel ctDNA targets. Methods: Plasma ctDNA was extracted from 43 non-metastatic IBC patients (IRB: LAB04-0698) pre, mid, and post-NAC. The Oncomine Pan Cancer ctDNA Assay (ThermoFisher) was used for library preparation, and high throughput next generation sequencing was performed on a GeneStudio S5XL System (ThermoFisher), following manufacturer’s directions. ThermoFisher Ion Reporter 5.10 Software was used to analyze single nucleotide variants (SNVs), and copy number variants (CNVs). Results: Seventeen patients had pre-NAC ctDNA assessments; 7/17 (41%) had PIK3CA SNVs; 5/7 also had MYC or FGFR2 CNVs. Five of 17 (29%) had TP53 SNVs; 2/5 also had FGFR2 CNVs. Ten patients had mid-NAC ctDNA assessments; 9/10 (90%) had PIK3CA SNVs; 5/9 also had FGFR2 CNVs, 2/9 had FGFR2 and FGFR3 CNVs, 2/9 also had TP53 SNVs, 1/9 had FGFR2 and ERB2 CNVs. Thirty-one patients had post-NAC ctDNA assessments; 5/31 (16%) had PIK3CA SNVs; 2/5 had FGFR2 CNVs, 1/5 also had a TP53 mutation and an FGFR2 CNV, 1/5 had FGFR2 CNV, and FGFR3 CNV. Six of 31 (19%) had TP53 SNVs, 1/6 had CCND1 CNVs, no CNVs were detected in 6 patients with TP53 SNVs. Six of 31 (19%) had MAP2K1 SNVs. Three of 31 (10%) had MET SNVs; 1/3 had CCND3 CNVs, no CNVs were detected in 2 patients with MET SNVs. No SNVs or CNVs were detected in 10/31 (32%) of patients post NAC. Conclusions: ctDNA assessments before, during, and after NAC identified novel targets that could be tested in future adjuvant therapies trials in IBC patients who remain at high risk for relapse.

Predicting treatment Response based on Dual assessment of magnetic resonance Imaging kinetics and Circulating Tumor cells in patients with Head and Neck cancer (PREDICT-HN): matching 'liquid biopsy' and quantitative tumor modeling

Background

Magnetic resonance imaging (MRI) has improved capacity to visualize tumor and soft tissue involvement in head and neck cancers. Using advanced MRI, we can interrogate cell density using diffusion weighted imaging, a quantitative imaging that can be used during radiotherapy, when diffuse inflammatory reaction precludes PET imaging, and can assist with target delineation as well. Correlation of circulating tumor cells (CTCs) measurements with 3D quantitative tumor characterization could potentially allow selective, patient-specific response-adapted escalation or de-escalation of local therapy, and improve the therapeutic ratio, curing the greatest number of patients with the least toxicity.

Methods

The proposed study is designed as a prospective observational study and will collect pretreatment CT, MRI and PET/CT images, weekly serial MR imaging during RT and post treatment CT, MRI and PET/CT images. In addition, blood sample will be collected for biomarker analysis at those time intervals. CTC assessments will be performed on the CellSave tube using the FDA-approved CellSearch® Circulating Tumor Cell Kit (Janssen Diagnostics), and plasma from the EDTA blood samples will be collected, labeled with a de-identifying number, and stored at − 80 °C for future analyses.

Discussion

The primary objective of the study is to evaluate the prognostic value and correlation of weekly tumor response kinetics (gross tumor volume and MR signal changes) and circulating tumor cells of mucosal head and neck cancers during radiation therapy using MRI in predicting treatment response and clinical outcomes. This study will provide landmark information as to the utility of CTCs (‘liquid biopsy) and tumor-specific functional quantitative imaging changes during treatment to guide personalization of treatment for future patients. Combining the biological information from CTCs and the structural information from MRI may provide more information than either modality alone. In addition, this study could potentially allow us to determine the optimal time to obtain MR imaging and/ or CTCs during radiotherapy to assess tumor response and provide guidance for patient selection and stratification for future dose escalation or de-escalation strategies.

Trial registration

Clinicaltrials.gov (NCT03491176). Date of registration: 9^th April 2018. (retrospectively registered). Date of enrolment of the first participant: 30^th May 2017.

Circulating Tumor Cells in Stage IV Melanoma Patients

BACKGROUND

Management of stage IV melanoma patients remains a challenge. In spite of promising new therapies, many patients develop resistance and progression. The aim of this pilot study was to determine if circulating tumor cells (CTCs) are associated with shortened (180-day) progression-free survival (PFS) after a baseline CTC assessment in stage IV melanoma patients.

STUDY DESIGN

A baseline CTC assessment was performed in 93 stage IV melanoma patients using a commercially available immunomagnetic system. The presence of 1 or more CTC was considered a positive result. A Cox multivariable regression model was used to evaluate the association between presence of CTCs at baseline and PFS, after adjusting for covariables. Kaplan-Meier curves and a log-rank test were used to summarize and compare unadjusted PFS for patients stratified by CTC positivity.

RESULTS

Median follow-up was 17 months; mean age was 55 years. Thirteen of 93 (14%) patients had no evidence of disease (NED) at baseline CTC assessment. One or more CTC was detected in 39 of 93 (42%) of patients at baseline; CTCs were not associated with primary melanoma features or NED status. Twenty-eight of 93 (30%) patients progressed within 180 days of baseline draw, with 20 of 39 (51%) of the CTC-positive patients relapsing compared with 8 of 54 (15%) of the CTC-negative patients. In adjusted Cox models, a significant association was found suggesting worse PFS within 180 days for CTC-positive patients at baseline (vs CTC-negative) (hazard ratio 4.69, 95% CI 1.59 to 13.77, p = 0.005).

CONCLUSIONS

One or more CTCs at baseline were associated with progression within 180 days in stage IV melanoma patients. This information warrants further study of CTCs as a means of identifying patients at high-risk for disease progression.

Body mass index mediates the prognostic significance of circulating tumor cells in inflammatory breast cancer

BACKGROUND

Obesity (BMI≥30) may be an etiologic and prognostic factor in inflammatory breast cancer (IBC). We examined the relationship between BMI, pathologic complete response (pCR), and circulating-tumor-cell (CTC) levels in IBC.

METHODS

Cohort included IBC patients diagnosed 2005-2015 who had neoadjuvant chemotherapy during a prospective trial on CTCs and pathologic review describing pCR. Chi-square, logistic regression, and Cox proportional hazards models were used to identify clinicopathologic associations with event-free survival (EFS).

RESULTS

Of 73 patients, 61 (84%) had CTC values, 22 (30%) achieved a pCR, and 39 (53%) were obese. There was no difference between obese and non-obese patients for pCR rates (31% vs. 29%, p = 0.90) or presence of CTCs (23% vs. 26%, p = 0.80). Among non-obese patients, CTCs were associated with worse EFS (HR 11.69, p < 0.01), but among obese patients, there was no difference in EFS between those with and without CTCs.

CONCLUSIONS

BMI mediates CTCs' prognostic significance in IBC.

Prognostic Value of Circulating Tumor Cells Identified Before Surgical Resection in Nonmetastatic Breast Cancer Patients

BACKGROUND

Circulating tumor cells (CTCs) can be identified in approximately 25% of nonmetastatic breast cancer patients, and data are emerging regarding their prognostic significance. We hypothesized that CTCs identified before resection of the primary tumor would predict worse outcomes in nonmetastatic breast cancer patients.

STUDY DESIGN

We performed CTC enumerations on 509 patients with nonmetastatic breast cancer as part of an IRB-approved study. The CTCs (per 7.5 mL blood) were identified using the CellSearch System (Janssen). The presence of ≥1 CTC meeting morphologic criteria for malignancy was considered a positive result. Log-rank test and Cox regression analysis were applied to establish the association of CTCs with relapse-free and overall survival.

RESULTS

Median follow-up was 48 months and mean age was 53 years. Fifty-nine percent of patients (299 of 509) had tumors larger than 2 cm, and 46% (234 of 509) had positive lymph nodes. One hundred sixty-six patients received neoadjuvant chemotherapy (NACT) before CTC assessment, and 343 patients were chemonaïve. One or more CTC was identified in 43 of 166 (26%) NACT treated patients, and in 81 of 343 (24%) chemonaïve patients. Circulating tumor cells were not associated with tumor size, grade, or lymph node status (p = NS). Detection of 1 or more CTCs predicted decreased relapse-free (log-rank p < 0.001, hazard ratio [HR] 2.72, 95% CI 1.57 to 4.72; p < 0.001) and overall survival (log-rank p = 0.02, HR 2.29, 95% CI 1.12 to 4.67; p = 0.03) at 48 months of follow-up.

CONCLUSIONS

One or more CTCs identified before resection of the primary breast tumor predicted worse relapse-free and overall survival, irrespective of primary tumor size, grade, or lymph node positivity.

Circulating Tumor Cells and Recurrence After Primary Systemic Therapy in Stage III Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) is rare and aggressive, with poor survival. While circulating tumor cells (CTCs) predict outcome in non-IBC patients, little data exists regarding their prognostic significance in IBC. This prospective study analyzed blood samples for CTCs from 63 stage III IBC patients to determine if CTCs present after primary systemic chemotherapy predicted relapse. CTC identification was not associated with tumor characteristics, lymph node positivity, or complete pathologic response to systemic therapy. At mean follow-up of 38 months, multivariable analysis demonstrated that detection of one or more CTCs predicted shortened relapse-free (log-rank P = 0.005, hazard ratio [HR] = 4.22, 95% confidence interval [CI] = 1.67 to 10.67, Cox P = 0.002) but not overall survival (log-rank P = 0.54, HR = 1.53, 95% CI = 0.41 to 5.79, Cox P = 0.53). All statistical tests were two-sided. In this study, CTCs after primary chemotherapy identified IBC patients at high risk for relapse.

Detection of circulating melanoma cells in the blood of melanoma patients: a preliminary study

Significant prognostic heterogeneity exists within the substages of melanoma; therefore, novel prognostic biomarkers are needed to provide information on the risk of recurrence. Limited available data suggest prognostic significance for circulating melanoma cells (CMCs); there is a need for a sensitive, reproducible, and standardized identification technique. Using a semiautomated technology, we sought to determine whether CMCs could be identified reliably in stage I-IV melanoma patients and whether the presence of CMC correlated with known prognostic factors. CMCs were detected in the peripheral blood (7.5 ml) of patients with stage I-IV melanoma (n=89) using the CellSearch system. CD146 cells were immunomagnetically enriched; nucleated HMW-MAA/CD45/CD34 cells were considered CMCs. One or more CMCs was detected in 45% of all patients, varying with stage of disease (stages I/II, III, and IV: 35, 44, and 86%, respectively; P=0.03, for stage I/II vs. stage IV); 55% had one CMC, 32% had two CMCs, and 13% had three or more CMCs identified. The presence of CMCs in the blood was associated with histologic subtype, particularly in patients with stage I/II disease (superficial spreading 18% vs. acral lentiginous 75%). Using a semiautomated technique, CMCs can be identified in a significant number of melanoma patients. These data support further study with longer follow-up and longitudinal/serial time points to better determine the identification rates and prognostic significance of CMCs in stage I-IV melanoma patients.

Hematogenous metastasis of ovarian cancer: rethinking mode of spread

Ovarian cancer has a clear predilection for metastasis to the omentum, but the underlying mechanisms involved in ovarian cancer spread are not well understood. Here, we used a parabiosis model that demonstrates preferential hematogenous metastasis of ovarian cancer to the omentum. Our studies revealed that the ErbB3-neuregulin 1 (NRG1) axis is a dominant pathway responsible for hematogenous omental metastasis. Elevated levels of ErbB3 in ovarian cancer cells and NRG1 in the omentum allowed for tumor cell localization and growth in the omentum. Depletion of ErbB3 in ovarian cancer impaired omental metastasis. Our results highlight hematogenous metastasis as an important mode of ovarian cancer metastasis. These findings have implications for designing alternative strategies aimed at preventing and treating ovarian cancer metastasis.

Use of disseminated tumor cells to predict outcome in patients with stage I-III breast cancer

119

Background: Published studies from Europe have shown the presence of disseminated tumor cells (DTCs) to independently predict outcomes in patients with non-metastatic breast cancer. The purpose of this study was to assess the experience with DTCs at a tertiary cancer center and to see if these cells indeed predict outcomes in patients with stage I-III breast cancer. Methods: Clinical stage I-III breast cancer patients seen at a single tertiary cancer center provided consent to participate in an IRB-approved study involving collection of bone marrow (5 ml x 2 tubes) at the time of surgery for their primary breast cancer. DTCs were assessed by anti-CK antibody cocktail (AE1/AE3, CAM5.2, MNF 116, CK 8 and 18) following cytospin. A positive result was defined as the presence of one or more cells per 5 ml of bone marrow. Statistical analyses used chi-square and Fischer’s exact tests. Results: Three hundred and sixty-six patients were prospectively enrolled. Mean age was 53 years. Median follow-up was 32 months. DTCs were identified in 109 patients (30%). Ten percent of patients with DTCs (11/109) and 3% of patients without DTCs (8/257) died (p = 0.009). Overall survival (OS) in patients with DTCs was 30 months vs. 31 months in those without DTCs. DTCs did not predict relapse free survival (P=NS). On multivariate analysis the presence of DTCs was an independent predictor of worse overall survival (p < 0.0001). No correlation was observed between the presence of DTCs and lymph node metastases and/or other clinicopathologic variables. Conclusions: The presence of DTCs was an independent predictor of worse OS in patients with stage I-III breast cancer. Consideration should be given to the utilization of DTCs as predictors of outcome in clinical practice.

Circulating tumour cells in non-metastatic breast cancer: a prospective study

BACKGROUND

The identification of circulating tumour cells correlate with poor prognosis in metastatic breast cancer, but there are few data describing the importance of circulating tumour cells in patients with non-metastatic disease. Our aim was to establish if circulating tumour cells predicted worse outcome in patients with non-metastatic breast cancer.

METHODS

We prospectively collected data on circulating tumour cells at the time of definitive surgery from chemonaive patients with stage 1-3 breast cancer from February, 2005, to December, 2010. We deemed eligible all patients with operable breast cancer presenting at The University of Texas MD Anderson Cancer Center (Houston, TX, USA). Patients were ineligible if they had bilateral breast cancer or any other malignancy within 5 years of the diagnosis of the present cancer. We measured circulating tumour cells with the CellSearch System (Veridex, Raritan, NJ). We correlated findings of circulating tumour cells with standard tumour characteristics, including tumour size and grade; oestrogen and progesterone receptor and human epidural growth factor receptor 2 (HER2) status; and axillary lymph node status with χ(2) or Fisher exact tests. We assessed outcomes at a median follow-up of 35 months. Log-rank test and Cox regression analysis was applied to establish the association of circulating tumour cells with progression-free and overall survival.

FINDINGS

No patients reported adverse events or complications from blood collections. We identified one or more circulating tumour cells in 73 (24%) of 302 patients. Detection of one or more circulating tumour cells predicted both decreased progression-free survival (log-rank p=0·005; hazard ratio [HR] 4·62, 95% CI 1·79-11·9) and overall survival (log-rank p=0·01; HR 4·04, 1·28-12·8).

INTERPRETATION

The presence of one or more circulating tumour cells predicted early recurrence and decreased overall survival in chemonaive patients with non-metastatic breast cancer. These results suggest that assessment of circulating tumour cells might provide important prognostic information in these patients.

FUNDING

Society of Surgical Oncology, Morgan Welch Inflammatory Breast Cancer Program, The University of Texas MD Anderson Cancer Center, and the State of Texas Rare and Aggressive Breast Cancer Research Program.

Investigating cyclooxygenase-2 signaling in breast cancer-initiating cells

e21107

Investigating cyclooxygenase-2 signaling in breast cancer-initiating cells Background: Only a small fraction of breast tumor cells, breast cancer-initiating cells (CSC), have the ability to initiate tumor growth and metastasis. Some characteristics of breast CSCs have been described in vitro by employing non-adherent CSC-enriching culture conditions, however, little is known regarding prostanoid signaling or prostaglandin E2 (PgE2) production in CSCs. In this study we measured cyclooxygenase-2 (COX-2) and prostaglandin E2 receptor expression in CSCs and assessed the effects of COX-2 and Ep4 inhibition on in vitro CSC spheroid formation and PgE2 production. Methods: CSCs were cultured in serum-free medium using ultra low attachment plates. Cells were treated with vehicle, a COX-2 inhibitor (Celecoxib), or an EP4 inhibitor (GW627368X) at concentrations of 0.1, 1, 5, 10, 50, or 100uM for 10 days. Spheroids were quantified using a Gelcount machine. Non-linear regression was used to calculate IC50 values. Western blots were performed using anti-COX-2, anti- EP1, 2, 3 and 4 receptor antibodies. Prostaglandin E2 production was measured using a PgE2 immunoassay kit. Results: COX-2 protein expression was observed for MDA-MB-231 and SUM149 CSCs. EP2 and EP4 protein was detected for MCF-7, MDA-MB-231, and SUM149 CSCs. The Celecoxib IC50 values for MCF-7 and SUM149 CSC spheroid formation were 0.5 and 2.2 uM, respectively; GW627386X IC50 values for MCF-7 and SUM149 CSC spheroid formation were 1.2 and 0.3uM, respectively. No significant differences in PGE2 production were observed for MCF-7 CSCs compared to adherent MCF-7 cells (11.5 ± 4.4 vs. 8.7 ± 2.1 pg/mL/106 cells; p=0.88). However, PgE2 production in MDA-MB-231 CSCs was significantly higher than adherent MDA-MB-231 cells (1507.0 ± 329.0 vs. 13.8 ± 5.7 pg/mL/106 cells; p≤0.001) and SUM149 CSC PgE2 production was significantly higher than SUM149 adherent cells (4932.9 ± 501.7 vs. 194.5 ± 31.0 pg/mL/106 cells; p≤0.001). 10uM Celecoxib treatment inhibited PGE2 production in MDA-MB-231 and MDA-MB-231 CSCs. Conclusions: MDA-MB-231 and SUM149 CSCs express COX-2, EP2 and Ep4 and produce high levels of PGE2. CSC spheroid formation is significantly decreased with COX-2 and EP4 inhibition.

Detection of discordant HER2 status by FISH in circulating tumor cells and disseminated tumor cells in early-stage breast cancer using a microfluidic-based cell enrichment and extraction platform (OncoCEE)

TPS10631

Background: Evaluation of HER2 in circulating (CTCs) and disseminated (DTC) tumor cells may aid therapy in breast cancer. We report here the discordance in HER2 status in CTCs and DTCs in early stage breast cancer by fluorescence in situ hybridization (FISH) using a microfluidic cell platform (OncoCEE). Methods: Blood (10ml) and BM (1-2ml) from patients with Stage T1 and T2 breast cancer was collected in OncoCEE-Sure collection tubes. Mononuclear cells were recovered using a Percoll density gradient method, incubated with a mixture of 10 primary capture antibodies (Abs), and introduced into streptavidin coated OncoCEE microchannels for tumor cell capture. For blood samples, captured cells were stained with anti cytokeratin (CK) and CD45 Abs for CTC enumeration followed by FISH using probes specific to centromere 17 and HER2. For BM samples, captured cells were subjected to HER2 FISH analysis. The ratio of HER2:CEP17>2.0 in any CK+/ CD45- and CK-/CD45- cell was regarded as positive for HER2. Results: Blood and BM from 68 patients (68 Blood, 54 BM; 54 matched blood and BM) with stage T1N0 (41), T1N1 (6), T2N0 (11), T2N1(2), T2N2 (1), T2N3 (2) with HER2+ (n=7) and HER2- (n=61) breast cancers were studied. The 7 patients with HER2 + primary tumor had HER2+ DTCs in 3/7 (43 %) and HER2 + CTCs in 1/6 (17 %) patients. HER2 + DTCs and HER2 + CTCs occurred in 10/47 (21%) and in 4/57 (7%) patients with HER2- primary breast tumors. The discordance of HER2 status was observed in 14% in CTCs and in 22% in DTCs. Conclusion: 1. The cell enrichment and extraction microfluidic platform (OncoCEE) provides a sensitive approach for evaluation of HER2 in CTCs and DTCs. 2. CTCs and DTCs acquired HER2 gene amplification in 21% and 7% of patients with HER2 negative early stage primary breast cancer. 3. CTCs and DTCs lost HER2 gene amplified status in 57% and 83% of patients with HER2 positive early stage primary breast cancer. 4. The clinical significance of alterations in HER2 status among CTCs and DTCs in early stage breast cancer needs further investigation.

Abstract 1368: Investigating the tumorigenicity of disseminated tumor cells

Background: Tumor cells that disseminate to the bone marrow (disseminated tumor cells, DTCs) have been identified in 30% of stage I - III breast cancer (BC) patients and independently predict outcome. Because DTCs are a rare, heterogeneous population of cells, little is known regarding their characteristics; such as their clinical significance with regard to disease progression, and targets that can be utilized for their eradication. DTC Identification is typically achieved using antibodies to epithelial cell adhesion molecule (EpCAM), and cytokeratin (CK). However, EpCAM and CK can be down-regulated during epithelial–mesenchymal transition (EMT). To date, no published report has assessed the tumorigenicity of DTCs isolated from patient samples using an in vivo animal model. The purpose of this study was to investigate the tumorigenicity of DTCs in vivo. Methods: Thirteen clinical stage I-III BC patients provided informed consent to participate in an IRB-approved study involving collection of bone marrow at the time of primary surgery. Following Ficoll centrifugation, bone marrow aspirates were cultured using breast cancer stem cell enriching conditions for 21 days. At 21 days, viability of floating cells with high nuclear: cytoplasmic ratios were confirmed with Tryphan blue staining and cytokeratin expression was identified using pan-cytokeratin immunostaining. 200 cells were co-injected with Matrigel into the mammary fat pads (3 mice/patient) of female nude mice. Mice were monitored daily for tumor formation. Results: Viable floating cells with large nuclear: cytoplasmic ratios were observed in 10/13 cases. Both CK+ and CK- DTCs were identified in 8 out of 10 cases, and CK- DTCs only were identified in 2 out of 10 cases. One of the 10 samples was tumorigenic in vivo; all 3 mice injected with this patient's cells developed breast tumors within ≤ 55 days. This sample was obtained from a 40-year old T2N2 patient with a grade 2 estrogen receptor positive, progesterone receptor negative, Her2/neu negative tumor. Interestingly, CK expression was not detected in this patient's cultured cells. Conclusions: DTCs can be isolated and propagated using breast cancer stem cell enriching conditions, enabling the characterization and assessment of DTCs that are in the process of (or have undergone) EMT. In addition, the tumorigenetic potential of DTCs can be assessed on a patient-by-patient basis by employing an in vivo mouse model. Further studies are needed to develop targeted therapies for the eradication of micrometastatic disease in stage I-III BC patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1368. doi:1538-7445.AM2012-1368

P4-06-04: Detection of HER2 Gene Amplification in Circulating Tumor Cells and Disseminated Tumor Cells by Fluorescence In Situ Hybridization Using OncoCEE™

BACKGROUND: The status of HER2 gene amplification in circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) might provide useful information for monitoring response to trastuzumab therapy, and may provide a basis for consideration of trastuzumab in patients with HER2 negative primary tumors who have HER2 positive CTCs and/or DTCs. The majority of techniques utilized for detection of minimal residual disease are limited in their ability to allow detailed phenotypic and genotypic evaluation of the cells. We report the utility of a microfluidic platform (OncoCEE™,Biocept, San Diego) for detecting HER2 gene amplification in CTCs and DTCs in patients with non-metastatic breast cancer.

METHODS: Peripheral blood (10ml) and bone marrow (BM) (1-2ml) were collected from patients with clinical stage I-III breast cancer in acid citrate dextrose solution (BD, Franklin Lakes, NJ) and anti-clumping reagent (OncoCEE-Sure™). Mononuclear cells were recovered using a Percoll density gradient method, incubated with a mixture of 10 primary capture antibodies (Abs), introduced into CEE™ microchannels, stained with fluorescent anti cytokeratin (CK) and CD45 abs and finally processed for fluorescence in situ hybridization (FISH) using probes specific to centromere 17 (spectrum green) and HER2 (spectrum arrange). The ratio of HER2:CEP17 &gt;2.2 in any CK+/CD45- and CK-/CD45- cell was regarded as positive for HER2 gene amplification.

RESULTS: Peripheral blood and/or BM from 78 patients (65 BM; 70 blood; 57 matched blood and BM) with T1NO (39), T1N1 (8), T2N0 (12), T2N1 (2), T2N2 (1), T2N3 (3), T3N0 (2), T3N1 (2), T3N2 (1), T4N0(5), T4N1 (3), with HER2+ (n=12) and HER2− (n=58) primary invasive breast tumors were studied. The 12 patients with HER2+ primary tumors had HER2+ DTCs in 3/12 (25%) and HER2+ CTCs in 1/9 (11%) cases respectively. HER2+ DTCs and HER2+ CTCs occurred in 12/55 (24%) and in 4/63 (6%) of the patients with HER2− primary breast tumors. HER2+ CTCs and DTCs occurred simultaneously in only 2 patients and in either blood (3) or BM (13) in the remaining patients.

CONCLUSION: 1. The cell enrichment and extraction microfluidic technology (OncoCEE™) provides a sensitive platform for evaluation of HER2 gene amplification of CTCs and DTCs.

2. HER2+ primary tumors were associated with either HER2+ CTCs or DTCs in 25% of the patients.

3. HER2+ CTCs or DTCs occurred in 28% of patients with HER2−primary tumor.

4. Discordant HER2 status was contributed mainly by HER2+ DTCs occurring in HER2 - primary tumors.

5. The clinical significance of evaluating the status of HER2 gene amplification in CTCs and DTCs in the management of patients with breast cancer needs to be evaluated prospectively in larger clinical trials.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-06-04.

Abstract P3-02-01: Is Ethnicity a Predictor of Micrometastatic Disease in Early Stage Breast Cancer Patients?

Background: Ethnicity plays a role in breast cancer (BC) outcome, highlighted by the fact that African-American women have a higher BC mortality rate than do Caucasian women. Microscopic disease, including disseminated tumor cells (DTCs) in bone marrow and circulating tumor cells (CTCs) in peripheral blood, has been shown to predict worse outcomes as well. We sought to determine whether ethnicity was a significant predictor for the presence of DTCs and/or CTCs in stage I-III BC patients.

Methods: Patients provided informed consent to participate in an IRB-approved study involving collection of blood and bone marrow at the time of surgery for their primary BC. CTCs (per 7.5 ml blood) were detected using the Cell SearchTM system (Veridex) and were defined as nucleated cells lacking CD45 but expressing cytokeratins (CK) 8, 18, or 19; for this study we considered one or more positive cells meeting these criteria a positive result. DTCs were assessed using an anti-CK antibody cocktail (AE1/AE3, CAM5.2, MNF116, CK8 and 18) following cytospin. A positive result for DTCs was defined by presence of one or more CK positive cells meeting morphologic criteria for malignancy. Information on clinicopathological factors including ethnicity was obtained from a prospective database. Statistical analyses used Chi-square test on STATA IC11.

Results: We prospectively evaluated 224 patients undergoing surgery for stage I-III BC. Median follow-up was 22 months and mean age was 53 years. One hundred sixty seven patients (75%) were Caucasians, 22 (10%) were African-American (AA), 30 (14%) were Hispanic and 3 (1%) belonged to other ethnicities. CTCs were found in 25% (57/224) and DTCs in 30% (67/224) of patients. Patients of AA ethnicity were significantly more likely to have CTCs (50%, (11/22)) compared to the other ethnic groups (22%, (43/194)); {O.R. = 2.5, 95% C.I. = 1.35- 7.80, P = 0.002}, and had significantly higher numbers of CTCs (≥2 CTCs or ≥3 CTCs/7.5mL blood) than other ethnic groups (P = 0.001 and P &lt; 0.001, respectively). No statistically significant correlation was observed between other ethnic groups and CTCs. Patients of Hispanic origin were more likely to have DTCs (60%, (18/30)) as compared to other ethnic groups (25%, (49/194)); {O.R. = 4.4, 95% C.I. = 1.85- 10.80, P &lt; 0.0001}, while DTCs were less likely to be found in Caucasians (26%, (44/167)) as compared to the other ethnicities (40%, (23/57)); {O.R. = 0.52, 95% C.I. = 0.27 — 1.05, P = 0.046}. No significant association was found between occurrence of DTCs and AA ethnicity. In a multivariate analysis considering lymph node status, tumor size and tumor markers, ethnic origin was an independent predictor of microscopic disease.

Conclusions: Nearly one-third of primary BC patients have CTCs and/or DTCs. African-American women were much more likely to have CTCs and Hispanic patients had significantly more DTCs than did patients of other ethnicities. Ethnicity was an independent predictor of microscopic disease. These findings may shed some light on the higher BC mortality rates found in certain ethnic groups.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-02-01.

Abstract P3-02-02: Influence of Body Mass Index on Presence of Disseminated Tumor Cells in Clinical Stage I-III Breast Cancer Patients

Background: Disseminated tumor cells (DTCs) are found in approximately one third of clinical stage I-III breast cancer (BC) patients, and published reports show that presence of DTCs is an independent predictor of outcome. While higher body mass index (BMI) is associated with increased risk of breast cancer recurrence and lower survival rates in BC patients, women with lower BMIs may have lower bone density and higher bone turnover. We hypothesized that increases in bone turnover may result in the release of bone growth and “homing” factors that facilitate BC metastasis to bone and provide a “pre-metastatic niche” for BC cells. The purpose of this study was to determine if a correlation existed between DTCs and BMI in early stage BC patients.

Methods: We obtained informed consent and collected bone marrow samples from 262 clinical stage I-III BC patients who were participants in an IRB-approved clinical study from 2/2005- 2/2010. All marrow samples were collected at the time of surgery for the primary tumor. DTCs were assessed using anti-pancytokeratin (CK) antibody cocktail (AE1/AE3, CAM5.2, MNF116, CK8 and 18) following cytospin. The presence of one or more CK positive cells meeting morphologic criteria for malignancy was considered a positive result for DTC. Patients with a BMI of (18.5 — 24.9) kg/m2 were considered “normal weight”, those with a BMI of (25 - 29.9) kg/m2 “overweight” and a BMI greater than 30 kg/m2 was used to designate them as “obese”. Information on clinicopathological factors including BMI (measured on initial presentation) was obtained from a prospective database. Statistical analyses used Chi-square and non-parametric tests for trend.

Results: Median follow-up was 19 months and mean age was 53 (25-80) years. Eighty-four patients (32%) were normal weight, 85 (32%) were overweight and 91 (35%) were obese. Seventy-eight (30%) patients had DTCs present at the time of assessment. Obese patients were significantly less likely to show presence of DTCs as compared to those who had a BMI &lt; 30 kg/m2 (20/78; 26% vs. 71/184; 39%) {O.R. = 0.55, 95% C.I. = 0.29- 0.96, P = 0.03}. DTCs were also less likely to be found in patients with BMI ≥25 kg/m2 as compared to those with BMI &lt; 25 kg/m2 (40/78; 51% vs. 136/184; 74%); {O.R. = 0.42, 95% C.I. = 0.04- 1.02, P = 0.03}. No statistically significant correlation was observed between primary tumor characteristics (ER, PR, HER2, lymph node status, tumor grade) and presence of DTCs. Finally, a non-parametric analysis demonstrated a trend in occurrence of DTCs across the ordered levels of patients’ BMI values (P= 0.013).

Conclusions: DTCs were much more common in patients with lower BMI. Further studies are needed to determine if patients with low BMI have unique microenvironmental factors within the bone that predisposes them to tumor cell dissemination.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-02-02.

Detection of minimal residual disease in blood and bone marrow in early stage breast cancer

BACKGROUND

The significance of circulating tumor cells (CTCs) in blood and of disseminated tumor cells (DTCs) in bone marrow (BM) in patients with early stage breast cancer is unclear. In this study, the authors investigated the occurrence of CTCs and DTCs in women with early stage breast cancer and evaluated the correlation of their presence with other prognostic markers.

METHODS

Blood and BM aspirations were collected at the time of primary breast surgery. CTCs were detected by using the CellSearch assay, and DTCs were detected by immunostaining BM aspirates for pancytokeratin. The presence of CTCs and DTCs was correlated with tumor classification (T1 vs T2), tumor histologic grade, estrogen receptor (ER) status, progesterone receptor (PR) status, human epidermal growth factor receptor 2 (HER2) status, and lymph node (LN) status.

RESULTS

Of 92 patients who were included in the study, 49 had T1 tumors, and 43 had T2 tumors. CTCs were detected in 31% of patients, and DTCs were detected in 27% of patients. There was no correlation between the occurrence of CTCs and DTCs with the tumor classification (T1 vs T2) or histologic grade. CTCs were detected in 33% of patients with ER-positive disease versus 26% of patients with ER-negative disease, in 32% of patients with PR-positive disease versus 30% of patients with PR-negative disease, and in 25% of patients with HER2-positive disease versus 31% of patients with HER2-negative disease. DTCs were observed in 23% of patients with ER-positive disease versus 37% of patients with ER-negative disease, in 22% of patients with PR-positive disease versus 32% of patients with PR-negative disease, and in 0% of patients with HER2-positive disease versus 29% of patients with HER2-negative disease. CTCs and DTCs were nearly equally prevalent in both LN-positive women and LN-negative women. There was no significant correlation between the occurrence of CTCs or DTCs with tumor classification (T1 vs T2), tumor histologic grade, positive ER status, positive PR status, or positive HER2 status, and axillary LN status.

CONCLUSIONS

CTCs and DTCs in women with early stage breast cancer did not correlate with the standard prognostic indicators that were considered. The implications of their occurrence in patients with early stage disease will require further large-scale studies.

Evidence based review of perioral dermatitis therapy

Perioral dermatitis presents as an eruption of erythematous papules, pustules and papulovesicles, most frequently seen in young women. Oral tetracyclines have been considered the first line treatment for years. However, recent publications have found newer agents to be efficacious. The authors performed a review of the available data in order to determine the strength of evidence supporting published therapies. A Pubmed and Cochrane Library database search for all cases, case series, and clinical trials dealing with the treatment of perioral dermatitis in English. Most cases of perioral dermatitis are self-limited, if the possible exacerbants of cosmetics and topical corticosteroids are discontinued ("zero therapy"). Many trials support the use of oral tetracyclines as a first line medication, as it significantly shortens the time to papule resolution. Topical erythromycin also reduces the time to resolution, but not as quickly. Topical pimecrolimus does not appear to decrease the time to complete resolution, but it does rapidly reduce the severity of the disease, particularly if prior corticosteroid use has occurred. The evidence supporting topical metronidazole, which is frequently used to treat perioral dermatitis in children, is relatively weak and supported only by case series and a trial showing it to be inferior to tetracycline. The evidence most strongly supports the efficacy of zero therapy, topical pimecrolimus, oral tetracycline, and topical erythromycin.

Suberoylanilide hydroxamic acid blocks self-renewal and homotypic aggregation of inflammatory breast cancer spheroids

BACKGROUND

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer (LABC). Patients with IBC commonly present with skin metastasis, which are observed microscopically as tumor emboli within dermal lymphatics. These metastatic tumor cells aberrantly overexpress E-cadherin and exhibit the ability to undergo self-renewal and are highly invasive. There are no therapeutics yet identified that target the structure and functions of IBC tumor emboli. The present studies evaluated the effects of the pan-histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) using IBC tumor spheroids derived from established IBC cell lines and tumor spheroids derived from pleural effusion (PE) aspirates of patients with IBC and LABC, designated as PE-IBC and PE-LABC.

METHODS

Methods used are as follows: culture of IBC cells from clonal density single cells in low adherence culture conditions that promote formation of IBC tumor spheroids; clonogenic assays; cell fractionation and Western blotting; confocal microscropy; and modified Boyden chamber invasion assays.

RESULTS

SAHA inhibited self-renewal of IBC tumor spheroids from established IBC cell lines and PE-IBC and PE-LABC, as assessed by decreased clonogenic growth. SAHA blocked homotypic aggregation of the cells that comprised the IBC tumor spheroids leading to loss of their 3-dimensional (3D) structure, which was associated with a change in location of E-cadherin protein from the plasma membrane in untreated IBC tumor spheroids to the cytoplasm of cells within IBC tumor spheroids with SAHA treatment. In addition, SAHA blocked the robust invasion exhibited by IBC tumor spheroids of established cell lines as well as by tumor spheroids derived from PE-IBC and PE-LABC.

CONCLUSIONS

SAHA targets the integrity and biological activities of IBC tumor spheroids and may be a promising agent to evaluate for its effectiveness in treatment of IBC.

The Narcissistic Personality Inventory: Alternative Form Reliability and Further Evidence of Construct Validity

The aim of this study was twofold: (a)to measure the alternate form reliability of the Narcissistic Personality Inventory, and (b)to determine its construct validity by correlating it with the four scales of the Eysenck Personality Questionnaire (EPQ). The alternate form reliability was .72. The Extraversion and Psychoticism scales of the EPQ were positively and significantly correlated with the narcissism measure, and the Lie scale showed a significant negative correlation. The Neuroticism scale showed a nonsignificant relationship with narcissism. In addition, the combined Extraversion and Psychoticism scales produced[ a Multiple R with the narcissism measure that accounted for significantly more of the variance in narcissism than did either measure alone.

Abstract 1461: Zoledronate inhibits proliferation and invasion of inflammatory breast cancer cells

Introduction: Inflammatory breast cancer (IBC) is aggressive, as approximately one third of patients present with distant metastases. Bisphosphonates are often administered to breast cancer patients for cancer-induced osteolysis. Recent evidence suggests bisphophanates may also have anti-tumor properties. This study examined the effects of the bisphosphonate, zoledronate (ZA), on the proliferation and invasive capabilities of highly aggressive IBC cell lines.

Methods: The IBC cell line SUM149 was cultured utilizing both adherent and serum-free, non-adherent cancer stem cell enriching conditions. An MTT assay was used to quantify proliferation and mammosphere formation of cells. Adherent cell growth was measured at days 1-4 following 0, 0.1, 1, 5, 10, 50 and 100uM zelodronate treatment. Mammosphere formation was measured at 10 days following 0, 0.01, 0.1, 1, 10, and 100uM ZA treatment. Modified Boyden chambers were employed to assess the ability of both adherent and non-adherent cells to invade to SDF-1 (100ng/mL) following 24 hour 1uM ZA treatment. Protein expression was assessed using immunofluorescent staining, protein arrays and Western blotting.

Results: ZA treatment with &lt;5uM did not inhibit SUM149 adherent cell growth at any of the measured time points. ZA concentrations ≥10uM significantly inhibited SUM149 adherent cell growth at day 4 (p≤0.05). SUM 149 mammosphere formation was significantly inhibited following 10uM ZA treatment (p≤0.001). However, significantly more SUM149 non-adherent cells invaded to SDF-1 compared to adherent cells (p≤0.001). SUM 149 non-adherent cell invasion was inhibited by 24 hour 1uM ZA treatment (p≤0.001). SUM 149 non-adherent cells expressed significantly increased levels of the epithelial-mesenchymal transition (EMT) associated proteins smooth muscle actin (SMA), fibronectin, and N-Cadherin. The increased expression of SMA, fibronectin, and N-Cadherin observed in non-adherent cells returned to levels comparable to adherent cells following 24 hour 1uM ZA treatment.

Conclusions: ZA inhibited the growth of IBC cells grown under adherent and non-adherent conditions. SUM 149 non-adherent cells had much greater invasive potential than adherent cells did, and their invasive capability was inhibited following low dose ZA treatment. Interestingly, ZA inhibited up-regulation of EMT associated proteins SMA, fibronectin, and N-Cadherin in SUM 149 non-adherent cells. These results indicate that some IBC cells grown under cancer stem cell enriching conditions have the potential to undergo EMT and invade. ZA may also inhibit metastases through novel mechanisms.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1461.

Significance of micrometastasis in bone marrow and blood of operable breast cancer patients: research tool or clinical application?

Approximately 25% of breast cancer patients without lymph node metastases develop systemic relapse. A growing body of data supports the notion that hematogenous dissemination of breast cancer cells occurs independently of lymphatic spread of disease; however, current clinical practice does not involve routine analysis of circulating or disseminated cells. Recent studies have documented that both circulating tumor cells (CTCs) within the blood and disseminated tumor cells (DTCs) in bone marrow can be identified using a variety of techniques. It is now clear that the presence of DTCs correlates with subsequent development of clinically evident bone metastases, and a worse outcome from breast cancer. While there are data identifying prognostic significance of CTCs in patients with metastatic breast cancer, there are few data regarding CTCs in operable patients. Factors such as presence of a cancer stem cell phenotype and/or certain microenvironmental conditions are involved in the establishment of distant metastases from a primary breast cancer, emphasizing the need for further studies within this area. The purpose of this report is to review the data regarding CTCs and DTCs in patients with operable breast cancer.

Receptor Activity-modifying Protein (RAMP) Isoform-specific Regulation of Adrenomedullin Receptor Trafficking by NHERF-1

Receptor activity-modifying proteins (RAMPs 1-3) are single transmembrane accessory proteins critical to various G-protein coupled receptors for plasma membrane expression and receptor phenotype. A functional receptor for the vasodilatory ligand, adrenomedullin (AM), is comprised of RAMP2 or RAMP3 and calcitonin receptor-like receptor (CRLR). It is now known that RAMP3 protein-protein interactions regulate the recycling of the AM2 receptor. The major aim of this study was to identify other interaction partners of RAMP3 and determine their role in CRLR-RAMP3 trafficking. Trafficking of G-protein-coupled receptors has been shown to be regulated by the Na+/H+ exchanger regulatory factor-1 (NHERF-1), an adaptor protein containing two tandem PSD-95/Discs-large/ZO-1 homology (PDZ) domains. In HEK 293T cells expressing the AM2 receptor, the complex undergoes agonist-induced desensitization and internalization. However, in the presence of NHERF-1, although the AM receptor (CRLR/RAMP3) undergoes desensitization, the internalization of the receptor complex is blocked. Overlay assays and mutational analysis indicated that RAMP3 and NHERF-1 interact via a PDZ type I domain on NHERF-1. The internalization of the CRLR-RAMP complex was not affected by NHERF-1 when CRLR was co-expressed with RAMP1 or RAMP2. Mutation of the ezrin/radixin/moesin (ERM) domain on NHERF-1 indicated that NHERF-1 inhibits CRLR/RAMP3 complex internalization by tethering the complex to the actin cytoskeleton. When examined in a primary culture of human proximal tubule cells endogenously expressing the CRLR-RAMP3 complex and NHERF-1, the CRLR-RAMP complex desensitizes but is unable to internalize upon agonist stimulation. Knock-down of either RAMP3 or NHERF-1 by RNA interference technology enabled agonist-induced internalization of the CRLR-RAMP complex. These results, using both endogenous and overexpressed cellular models, indicate a novel function for NHERF-1 and RAMP3 in the internalization of the AM receptor and suggest additional regulatory mechanisms for receptor trafficking.

Novel Function for Receptor Activity-modifying Proteins (RAMPs) in Post-endocytic Receptor Trafficking

RAMPs (1-3) are single transmembrane accessory proteins crucial for plasma membrane expression, which also determine receptor phenotype of various G-protein-coupled receptors. For example, adrenomedullin receptors are comprised of RAMP2 or RAMP3 (AM1R and AM2R, respectively) and calcitonin receptor-like receptor (CRLR), while a CRLR heterodimer with RAMP1 yields a calcitonin gene-related peptide receptor. The major aim of this study was to determine the role of RAMPs in receptor trafficking. We hypothesized that a PDZ type I domain present in the C terminus of RAMP3, but not in RAMP1 or RAMP2, leads to protein-protein interactions that determine receptor trafficking. Employing adenylate cyclase assays, radioligand binding, and immunofluorescence microscopy, we observed that in HEK293 cells the CRLR-RAMP complex undergoes agonist-stimulated desensitization and internalization and fails to resensitize (i.e. degradation of the receptor complex). Co-expression of N-ethylmaleimide-sensitive factor (NSF) with the CRLR-RAMP3 complex, but not CRLR-RAMP1 or CRLR-RAMP2 complex, altered receptor trafficking to a recycling pathway. Mutational analysis of RAMP3, by deletion and point mutations, indicated that the PDZ motif of RAMP3 interacts with NSF to cause the change in trafficking. The role of RAMP3 and NSF in AM2R recycling was confirmed in rat mesangial cells, where RNA interference with RAMP3 and pharmacological inhibition of NSF both resulted in a lack of receptor resensitization/recycling after agonist-stimulated desensitization. These findings provide the first functional difference between the AM1R and AM2R at the level of post-endocytic receptor trafficking. These results indicate a novel function for RAMP3 in the post-endocytic sorting of the AM-R and suggest a broader regulatory role for RAMPs in receptor trafficking.

Negative growth effects of ciglitazone on kidney interstitial fibroblasts: role of PPAR-gamma

BACKGROUND/AIMS

Ciglitazone and other thiazolidinedione compounds are peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligands and improve renal function in diabetic nephropathy independent of blood glucose control. Because interstitial fibroblasts and glomerular mesangial cells are important cell types affected in diabetic nephropathy, the major aim of the present study was to examine the effect of ciglitazone on apoptosis and growth of renal interstitial fibroblasts (NRKs) and glomerular mesangial cells (MMCs).

METHODS

The effect of ciglitazone on apoptosis and cell growth of cultured NRKs and MMCs was done using DNA fragmentation and MTS cell-growth assays, respectively. The potential role of PPAR-gamma in these two cell types was examined by reporter gene analysis.

RESULTS

Ciglitazone induced caspase-dependent apoptosis of both NRKs and MMCs and caused a significant decrease in cell growth. Other PPAR-gamma ligands also mimicked this effect. Interestingly, ciglitazone did not activate the PPRE-TK-CAT (peroxisome proliferator regulatory element, a thymidine kinase promoter and a chloramphenicol acetyltransferase gene) when transfected into NRKs, suggesting that ciglitazone does not activate the endogenous PPAR-gamma system in NRKs. On the other hand, ciglitazone activated the endogenous PPAR-gamma in MMCs.

CONCLUSIONS

Apoptotic and negative growth effects of ciglitazone, in NRKs, are not mediated through PPAR-gamma. The thiazolidinediones have important cellular effects on renal interstitial fibroblasts and glomerular mesangial cells that may be therapeutically useful in non-diabetic renal disease.

Adrenomedullin Increases AP-1 Expression in Rat Mesangial Cells via Activation of Protein Kinase-A and p38 MAPK

Adrenomedullin (AM), a potent vasodilatory peptide, has anti-proliferative and pro-apoptotic effects in rat mesangial cells (RMCs). We have previously demonstrated that AM modulates activities of the members of MAPK family in RMCs. Because activation of MAPKs has been reported to induce AP-1 expression in other cell systems, the major aim of the present study was to examine the effects and mechanisms of AM on AP-1 member mRNA expression, in RMCs. AM produced a concentration- and time-dependent increase in c-fos and jun-B mRNA expression without observable effects on fos-B and c-jun. Associated with this change, AM increased the AP-1 DNA binding activity. RMCs transiently transfected with a luciferase fusion gene driven by an AP-1 cis-element demonstrate a concentration- and time-dependent increase in luciferase activity suggesting that AM increases AP-1-mediated gene transcription in these cultured cells. Both an AM-induced increase in AP-1 mRNA expression and AP-1 luciferase activities were inhibited by H89 (protein kinase-A inhibitor) and SB203580 (p38 MAPK inhibitor). These results indicate a likely role for the members of AP-1 family in AM-mediated biological responses in rat mesangial cells and a role for cAMP activation and subsequent activation of p38 MAPK in AM-induced AP-1 activity.

Mixed lineage kinase 3 inhibits phorbol myristoyl acetate-induced DNA synthesis but not osteopontin expression in rat mesangial cells

Mixed lineage kinase 3 (MLK 3) (also called SPRK or PTK-1) is a recently described member of the family of the mixed lineage kinase subfamily of Ser/Thr protein kinases that interacts with mitogen-activated protein kinase pathways. In order to test the biological relevance and potential interaction of MLK 3 with protein kinase C-mediated signaling pathways, human MLK 3 was stably expressed in rat glomerular mesangial cells using a retroviral vector (LXSN) and the effects of phorbol myristoyl acetate (PMA) on DNA synthesis and osteopontin mRNA expression were examined. In control (vector-transfected) mesangial cells PMA increased [3H]-thymidine incorporation in a concentration-dependent manner. In mesangial cells stably expressing MLK 3, the PMA-induced increase in [3H]-thymidine incorporation was significantly reduced (> 50%). However, the PMA-induced increase in osteopontin mRNA was not affected by MLK 3 expression. To determine the mechanisms of these effects, activation of ERK2, JNK1 and p38 in response to PMA was examined in both vector and MLK 3 transfected cells. ERK2 activation was increased several fold by PMA in control cells but was attenuated significantly in MLK 3 expressing cells, suggesting that MLK 3 expression in mesangial cells can negatively regulate the ERK pathway. PMA had no significant effect on JNK and P38 activation, in either vector- or MLK 3-expressing cells. PD98059, a MEK inhibitor blocked PMA-induced DNA synthesis without affecting osteopontin expression. These results suggest that while protein kinase C activation increases cellular proliferation and osteopontin mRNA expression, over-expression of MLK 3 affects only the PKC-induced DNA synthesis, probably through inhibition of ERK. These results also indicate a novel mechanism of growth regulation by a member of the mixed-lineage kinase family that might have significant therapeutic implications in proliferative glomerulonephritis.

Novel regulation of adrenomedullin receptor by PDGF: role of receptor activity modifying protein-3

Receptor activity modifying protein-3 (RAMP-3) has been shown to complex with the calcitonin receptor-like receptor, establishing a functional receptor for adrenomedullin (AM). AM exhibits potent antiproliferative and antimigratory effects on rat mesangial cells (RMCs). In this study we investigated the effect of platelet-derived growth factor (PDGF) on RAMP-3 expression in RMCs. We show here that PDGF-BB stimulates RAMP-3 mRNA expression in a concentration-dependent manner. Pretreatment with actinomycin-D and alpha-amanitin demonstrates that this effect is independent of new RNA synthesis. Furthermore, PDGF increased the half-life of RAMP-3 mRNA from 66.5 to 331.6 min. Using selective inhibitors, our results also indicate that the increase in RAMP-3 mRNA is mitogen-activated protein kinase (MAPK) kinase (MEK)/MAPK and p38 MAPK dependent. PDGF also caused a corresponding elevation in membrane-associated RAMP-3 protein. Associated with this increase, PDGF pretreatment led to a significantly higher AM-mediated adenylate cyclase activity, suggesting a functional consequence for the PDGF-induced increase in RAMP-3 expression. Taken together, these data identify PDGF-dependent regulation of RAMP-3 expression as a possible mechanism for modulating the responsiveness of the mesangial cell to AM.

Solvated electrons in very small clusters of polar molecules: (HF)(3)(-)

Photoelectron spectra of (HF)(3)(-) reveal coexistence of two anionic isomers with vertical electron detachment energies (VDE) of 0.24 and 0.43 eV. The results of electronic-structure calculations, performed at the coupled cluster level of theory with single, double, and noniterative triple excitations, suggest that the two isomers observed experimentally are an open, zigzag, dipole-bound anion and an asymmetric solvated electron, in which the dipole-bound anion of (HF)(2) is solvated by one HF monomer at the side of the excess electron. The theoretical VDE of 0.21 and 0.44 eV, respectively, are in excellent agreement with the experimental data.

Mixed lineage kinase 3 inhibits platelet-derived growth factor-stimulated DNA synthesis and matrix mRNA expression in mesangial cells

Mixed lineage kinase 3 (MLK 3) is a recently described member of the MLK subfamily of Ser/Thr protein kinases that interacts with MAPK pathways. The aim of this study was to test the potential interaction of MLK 3 with signaling pathways stimulated by PDGF in rat mesangial cells. We have established a stable cell line expressing human MLK 3 in rat glomerular mesangial cells. The effects of PDGF on proliferation and matrix mRNA expression were examined. In control (vector-transfected) mesangial cells PDGF increased [(3)H]-thymidine incorporation significantly in a concentration-dependent manner. In mesangial cells expressing MLK 3, PDGF-induced increase in DNA synthesis was significantly reduced. PDGF also induced fibronectin and collagen I mRNA expression in control cells, the effects of which were also significantly blocked in MLK 3-transfected cells. To understand the potential interaction of MLK 3 over expression with the MAPK pathways and to examine the potential mechanism of the effects of MLK 3 over expression on proliferation and matrix expression, activation of ERK2, JNK1 and p38 were examined. ERK2 activation was increased several fold by PDGF in control cells but was attenuated significantly in MLK 3 expressing cells. PDGF did not have any effect on JNK and p38 activation, in either cell types. Using the same stable-transfected cell line, identical results were obtained on proliferation and matrix expression with sarafotoxin-s6b (endothelin receptor agonist) another potent mitogenic and sclerotic agent for mesangial cells. These results indicate an important role for MLK 3 in the regulation of growth and matrix expression in mesangial cells.

Cellular and molecular actions of adrenomedullin in glomerular mesangial cells

Adrenomedullin (AM), a potent vasodilatory and hypotensive peptide produces several biological outcomes in glomerular mesangial cells. Mesangial cells are important in the pathogenesis of glomerulonephritis, and therefore the actions of AM on mesangial cells have important clinical and therapeutic implications. This minireview describes the various actions of AM on mesangial cell function and the signal transduction mechanisms involved. As in other systems, most actions of AM can be explained by increase in cAMP levels in the cell, although a few exceptions remain. The fact that most data obtained to date has been in culture, the physiological significance of the actions of AM in mesangial cells is discussed.

Temperature dependence of ultrasonic enhancement with a site-targeted contrast agent

Molecular imaging contrast agents specifically detect the biochemical "signatures" of disease before anatomical manifestations are apparent. Sensitive and specific localization of fibrin both in vivo and in vitro has been demonstrated with the use of a ligand-directed liquid perfluorocarbon nanoparticle. Since the acoustic properties of perfluorocarbons are known to vary with temperature, it was hypothesized that temperature could be used to augment the magnitude of enhancement imparted by targeted nanoparticles. Accordingly, the acoustic backscatter of two different substrates, nitrocellulose membrane and human plasma clot, targeted by the nanoparticles was measured at temperatures ranging from 27 degrees to 47 degrees C in 5 degrees C increments. Classic avidin-biotin interactions were utilized to couple biotinylated nanoparticles to avidin-conjugated nitrocellulose membranes. Ultrasonic contrast enhancement of the nitrocellulose membrane at 25 MHz, measured by acoustic microscopy, increased from 2.0+/-0.3 dB at 27 degrees C to 3.7+/-0.4 at 47 degrees C. In a similar experiment, antifibrin nanoparticles bound to human plasma clots also exhibited temperature-dependent ultrasonic signal enhancement ranging from 13.9+/-1.5 dB at 27 degrees C to 18.1+/-1.5 dB at 47 degrees C. The increase in ultrasonic contrast enhancement measured was well described by a simple, acoustic transmission line model with temperature-dependent impedance. These results suggest that temperature-dependent changes in acoustic backscatter may be used to further differentiate tissues targeted with site-specific nanoparticles from surrounding normal soft tissues.

FK506 promotes adenosine release from endothelial cells via inhibition of adenosine kinase

The immunosuppressants, cyclosporin A and tacrolimus (FK506) induce an increase in plasma levels of adenosine and mimic ischemic preconditioning. However, the mechanism of action of the two drugs on adenosine metabolism is not clear. Since inhibition of adenosine kinase promotes an increase in endogenous adenosine release, we tested a hypothesis that FK506 induces adenosine release via inhibition of adenosine kinase activity. In cultured endothelial cells, FK506 enhanced release of tracer adenosine and inhibited uptake of tracer adenosine. It also reduced adenosine kinase activity of the cell membrane fraction. In addition, FK506 does not inhibit membrane transport of tracer adenosine. These observations indicate that FK506 inhibits in situ adenosine kinase activity in endothelial cells. Other cell signaling inhibitors were found to inhibit adenosine uptake via inhibition of adenosine transport. In conclusion, FK506 promotes adenosine release from endothelial cells by a novel mechanism involving inhibition of adenosine kinase activity associated with the membrane.

Age-related alterations of cardiac tissue microstructure and material properties in Fischer 344 rats

The cardiac aging process is accompanied by global mechanical dysfunction that reflects increased myocardial stiffness. Accordingly, age-related changes in microscopic material properties of myocardium were delineated with high-frequency ultrasound (US) (30 to 44 MHz) tissue characterization methods for aging Fischer 344 rats at 6 (adult), 18 (aged), and 24 (senescent) months of age. The excised lateral wall of the left ventricle of rats (n = 10 per group) was insonified with a 50-MHz acoustic microscope for determination of integrated backscatter, backscatter coefficient and attenuation coefficient. Histological and biochemical analyses for collagen content and cardiac myocyte diameter were performed. Collagen concentration increased progressively with age, with the greatest increments occurring from 6 to 18 months (38.0 +/- 6.3 to 53.0 +/- 7.1 mg/g dry wt), and leveling off at 24 months (60.0 +/- 7.4 mg/g dry wt). Tissue microscopic material properties also changed progressively from 6 to 24 months of age, as determined by US methods: integrated backscatter increased (-44.7 +/- 1.8 vs. -40.8 +/- 1.9 dB, p < 0.05), attenuation increased (47.1 +/- 5.9 to 65.3 +/- 7.8 dB/cm, p < 0.05), and the backscatter coefficient increased (0.73 +/- 0.16 x 10(-5) to 3.76 +/- 1.6 x 10(-5) cm(-1), p < 0.05), from 6 to 24 months of age in each case. Age-related alterations in indices of cardiac microscopic material properties were closely correlated with the changes in cardiac microstructure. Ultrasonic tissue characterization may prove to be a sensitive tool to monitor changes in the cardiac microstructure, such as increased collagen deposition, that occur within age-related diastolic dysfunction.

Time evolution of enhanced ultrasonic reflection using a fibrin-targeted nanoparticulate contrast agent

Complex molecular signaling heralds the early stages of pathologies such as angiogenesis, inflammation, unstable atherosclerotic plaques, and areas of remote thrombi. In previous studies, acoustic enhancement of blood clot morphology was demonstrated with the use of a nongaseous, fibrin-targeted acoustic nanoparticle emulsion delivered to areas of thrombosis both in vitro and in vivo. In this study, a system was designed and constructed that allows visualization of the evolution of acoustic contrast enhancement. To evaluate the system, two targets were examined: avidin-complexed nitrocellulose membrane and human plasma clots. The time evolution of enhancement was visualized in 10-min increments for 1 h. A monotonic increase was observed in ultrasonic reflection enhancement from specially treated nitrocellulose membranes for targeted emulsions containing perfluorooctylbromide (1.30+/-0.3 dB) and for perfluorooctane (2.64+/-0.5 dB) within the first 60 min of imaging. In comparison, the inherently nonechogenic plasma clots showed a substantial increase of 12.0+/-0.9 dB when targeted with a perfluoro-octane emulsion. This study demonstrates the concept of molecular imaging and provides the first quantifiable time-evolution report of the binding of a site-targeted ultrasonic contrast agent. Moreover, with the incorporation of specific drug treatments into the nanoparticulate contrast agent, ultrasonic molecular imaging may yield reliable detection and quantification of nascent pathologies and facilitate targeted drug therapy.

High-resolution MRI characterization of human thrombus using a novel fibrin-targeted paramagnetic nanoparticle contrast agent

In this study, the sensitivity of a novel fibrin-targeted contrast agent for fibrin detection was defined in vitro on human thrombus. The contrast agent was a lipid-encapsulated perfluorocarbon nanoparticle with numerous Gd-DTPA complexes incorporated into the outer surface. After binding to fibrin clots, scanning electron microscopy of treated clots revealed dense accumulation of nanoparticles on the clot surfaces. Fibrin clots with sizes ranging from 0.5-7.0 mm were imaged at 4.7 T with or without treatment with the targeted contrast agent. Regardless of sizes, untreated clots were not detectable by T(1)-weighted MRI, while targeted contrast agent dramatically improved the detectability of all clots. Decreases in T(1) and T(2) relaxation times (20-40%) were measured relative to the surrounding media and the control clots. These results suggest the potential for sensitive and specific detection of microthrombi that form on the intimal surfaces of unstable atherosclerotic plaque.

Kramers-Kronig relations applied to finite bandwidth data from suspensions of encapsulated microbubbles

In this work, the Kramers-Kronig (K-K) relations are applied to experimental data of resonant nature by limiting the interval of integration to the measurement spectrum. The data are from suspensions of encapsulated microbubbles (Albunex) and have the characteristics of an ultrasonic notch filter. The goal is to test the consistency of this dispersion and attenuation data with the Kramers-Kronig relations in a strict manner, without any parameters from outside the experimental bandwidth entering in to the calculations. In the course of reaching the goal, the artifacts associated with the truncation of the integrals are identified and it is shown how their impacts on the results can be minimized. The problem is first approached analytically by performing the Kramers-Kronig calculations over a restricted spectral band on a specific Hilbert transform pair (Lorentzian curves). The resulting closed-form solutions illustrate the type of artifacts that can occur due to truncation and also show that accurate results can be achieved. Next, both twice-subtracted and lower-order Kramers-Kronig relations are applied directly to the attenuation and dispersion data from the encapsulated microbubbles. Only parameters from within the experimental attenuation coefficient and phase velocity data sets are used. The twice-subtracted K-K relations produced accurate estimates for both the attenuation coefficient and dispersion across all 12 data sets. Lower-order Kramers-Kronig relations also produced good results over the finite spectrum for most of the data. In 2 of the 12 cases, the twice-subtracted relations tracked the data markedly better than the lower-order predictions. These calculations demonstrate that truncation artifacts do not overwhelm the causal link between the phase velocity and the attenuation coefficient for finite bandwidth calculations. This work provides experimental evidence supporting the validity of the subtracted forms of the acoustic K-K relations between the phase velocity and attenuation coefficient.

In vivo molecular imaging of stretch-induced tissue factor in carotid arteries with ligand-targeted nanoparticles

Molecular imaging permits tissues to be functionally characterized by identification of specific cell-surface receptors with targeted contrast agents. In our study, a ligand-targeted acoustic nanoparticle system was used to identify the angioplasty-induced expression of tissue factor by smooth muscle cells within the tunica media. Pig carotid arteries were overstretched bilaterally with balloon catheters, treated with a tissue factor-targeted or a control nanoparticle system, and imaged with intravascular ultrasound (20 MHz) before and after treatment. Carotid wall acoustic reflectivities were unaffected by overstretch injury. Tissue factor-targeted nanoemulsion bound and increased the echogenicity of smooth muscle cells expressing tissue factor within the tunica media. The targeted emulsion increased the arterial wall gray scale (99.4+/-14.5; P<.05) relative to pretreatment (41.8+/-11.1, P<0.05) and the control gray scale (pre-emulsion: 49.3+/-9.5; post-emulsion: 43.7+/-6.4; P<.05). The area of acoustic enhancement appeared to coincide with expression of induced tissue factor in the tunica media confirmed by immunohistochemistry. We have demonstrated that this novel nanoemulsion can infiltrate into arterial walls after balloon injury and localize the expression of overstretch-induced tissue factor within pig carotid arteries. Molecular imaging and quantification of complex, biochemical change, such as tissue factor expression after angioplasty, may prove to be a prognostically important predictor of subsequent restenosis.

Delineation of the extracellular determinants of ultrasonic scattering from elastic arteries

Elastic arteries consist of three primary components: elastin fibers, extracellular collagen matrix and smooth muscle cells. However, the relative contribution of elastin and collagen fibers to overall ultrasonic scattering from an intact arterial wall is poorly understood. To define the principal source of extracellular scattering from the medial layer of elastic arteries, canine ascending aortas (n = 10) were excised, fixed and sectioned for insonification. Subsequently, aortic specimens were restudied after treatment to dissolve all tissue components except extracellular collagen matrix (n = 5) and elastin fibers (n = 5). Histological staining revealed very few elastin fibers and sparse intact collagen in collagen-isolated and elastin-isolated tissues, respectively. Integrated backscatter, attenuation and backscatter coefficients differentiated these two treated tissues. The backscatter coefficient for elastin-isolated tissue demonstrated a fivefold increase over collagen-isolated tissue, suggesting that elastin fibers represent a primary scattering component within elastic arteries, and the collagen fibers may provide a secondary component of scattering.

Molecular imaging of stretch-induced tissue factor expression in carotid arteries with intravascular ultrasound

RATIONALE AND OBJECTIVES

Molecular imaging with targeted contrast agents enables tissues to be distinguished by detecting specific cell-surface receptors. In the present study, a ligand-targeted acoustic nanoparticle system is used to identify angioplasty-induced expression of tissue factor by smooth muscle cells within carotid arteries.

METHODS

Pig carotid arteries were overstretched with balloon catheters, treated with tissue factor-targeted or a control nanoparticle system, and imaged with intravascular ultrasound before and after treatment.

RESULTS

Tissue factor-targeted emulsions bound and increased the echogenicity and gray-scale levels of overstretched smooth muscle cells within the tunica media, versus no change in contralateral control arteries. Expression of stretch-induced tissue factor in carotid artery media was confirmed by immunohistochemistry.

CONCLUSIONS

The potential for abnormal thrombogenicity of balloon-injured arteries, as reflected by smooth muscle expression of tissue factor, was imaged using a novel, targeted, nanoparticulate ultrasonic contrast agent.