Kristine L. Cooper

Invasive Lobular Carcinoma Cell Lines Are Characterized by Unique Estrogen-Mediated Gene Expression Patterns and Altered Tamoxifen Response

Invasive lobular carcinoma (ILC) is a histologic subtype of breast cancer that is frequently associated with favorable outcomes, as approximately 90% of ILC express the estrogen receptor (ER). However, recent retrospective analyses suggest that patients with ILC receiving adjuvant endocrine therapy may not benefit as much as patients with invasive ductal carcinoma. On the basis of these observations, we characterized ER function and endocrine response in ILC models. The ER-positive ILC cell lines MDA MB 134VI (MM134) and SUM44PE were used to examine the ER-regulated transcriptome via gene expression microarray analyses and ER ChIP-Seq, and to examine response to endocrine therapy. In parallel, estrogen response was assessed in vivo in the patient-derived ILC xenograft HCI-013. We identified 915 genes that were uniquely E2 regulated in ILC cell lines versus other breast cancer cell lines, and a subset of these genes were also E2 regulated in vivo in HCI-013. MM134 cells were de novo tamoxifen resistant and were induced to grow by 4-hydroxytamoxifen, as well as other antiestrogens, as partial agonists. Growth was accompanied by agonist activity of tamoxifen on ER-mediated gene expression. Though tamoxifen induced cell growth, MM134 cells required fibroblast growth factor receptor (FGFR)-1 signaling to maintain viability and were sensitive to combined endocrine therapy and FGFR1 inhibition. Our observation that ER drives a unique program of gene expression in ILC cells correlates with the ability of tamoxifen to induce growth in these cells. Targeting growth factors using FGFR1 inhibitors may block survival pathways required by ILC and reverse tamoxifen resistance.

Prognostic utility of the breast cancer index and comparison to Adjuvant! Online in a clinical case series of early breast cancer

IntroductionBreast Cancer Index (BCI) combines two independent biomarkers, HOXB13:IL17BR (H:I) and the 5-gene molecular grade index (MGI), that assess estrogen-mediated signalling and tumor grade, respectively. BCI stratifies early-stage estrogen-receptor positive (ER+), lymph-node negative (LN-) breast cancer patients into three risk groups and provides a continuous assessment of individual risk of distant recurrence. Objectives of the current study were to validate BCI in a clinical case series and to compare the prognostic utility of BCI and Adjuvant!Online (AO).MethodsTumor samples from 265 ER+LN- tamoxifen-treated patients were identified from a single academic institutions cancer research registry. The BCI assay was performed and scores were assigned based on a pre-determined risk model. Risk was assessed by BCI and AO and correlated to clinical outcomes in the patient cohort.ResultsBCI was a significant predictor of outcome in a cohort of 265 ER+LN- patients (median age: 56-y; median follow-up: 10.3-y), treated with adjuvant tamoxifen alone or tamoxifen with chemotherapy (32%). BCI categorized 55%, 21%, and 24% of patients as low, intermediate and high-risk, respectively. The 10-year rates of distant recurrence were 6.6%, 12.1% and 31.9% and of breast cancer-specific mortality were 3.8%, 3.6% and 22.1% in low, intermediate, and high-risk groups, respectively. In a multivariate analysis including clinicopathological factors, BCI was a significant predictor of distant recurrence (HR for 5-unit increase = 5.32 [CI 2.18-13.01; P = 0.0002]) and breast cancer-specific mortality (HR for a 5-unit increase = 9.60 [CI 3.20-28.80; P < 0.0001]). AO was significantly associated with risk of recurrence. In a separate multivariate analysis, both BCI and AO were significantly predictive of outcome. In a time-dependent (10-y) ROC curve accuracy analysis of recurrence risk, the addition of BCI+AO increased predictive accuracy in all patients from 66% (AO only) to 76% (AO+BCI) and in tamoxifen-only treated patients from 65% to 81%.ConclusionsThis study validates the prognostic performance of BCI in ER+LN- patients. In this characteristically low-risk cohort, BCI classified high versus low-risk groups with ~5-fold difference in 10-year risk of distant recurrence and breast cancer-specific death. BCI and AO are independent predictors with BCI having additive utility beyond standard of care parameters that are encompassed in AO.

Interobserver Agreement Among Pathologists for Semiquantitative Hormone Receptor Scoring in Breast Carcinoma

The American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) guidelines recommend reporting of hormone receptor test results in a semiquantitative manner. This study used 74 resected estrogen receptor (ER)-positive invasive breast cancers to determine reproducibility of semiquantitative scoring of hormone receptors using the H-score method. Four pathologists independently scored each slide. Agreement among observers was analyzed via Fleiss κ statistics on ER and progesterone receptor (PR) categorical scores. Intraclass correlation coefficient (ICC) was used to estimate the interobserver agreement for ER and PR H-scores on a continuous scale (0-300). There was 100% agreement for categorical ER results (κ = 1) and 97% agreement (κ = 0.823, P < .001) for categorical PR results. For quantitative H-scores, ICC agreement was 0.85 (95% confidence interval [CI] = 0.79-0.90) for ER and 0.87 (95% CI = 0.82-0.92) for PR. Because the H-score provides a continuous measure of tumor hormone receptor content, we suggest universal adoption of this method.

Alcohol and tobacco lower the age of presentation in sporadic pancreatic cancer in a dose-dependent manner: A multicenter study

OBJECTIVES:The objective of this study was to examine the association between tobacco and alcohol dose and type and the age of onset of pancreatic adenocarcinoma (PancCa).METHODS:Prospective data from the Pancreatic Cancer Collaborative Registry were used to examine the association between age of onset and variables of interest including: gender, race, birth country, educational status, family history of PancCa, diabetes status, and tobacco and alcohol use. Statistical analysis included logistic and linear regression, Cox proportional hazard regression, and time-to-event analysis.RESULTS:The median age to diagnosis for PancCa was 66.3 years (95% confidence intervals (CIs), 64.5–68.0). Males were more likely than females to be smokers (77% vs. 69%, P=0.0002) and heavy alcohol and beer consumers (19% vs. 6%, 34% vs. 19%, P<0.0001). In univariate analysis for effects on PancCa presentation age, the following were significant: gender, alcohol and tobacco use (amount, status and type), family history of PancCa, and body mass index. Both alcohol and tobacco had dose-dependent effects. In multivariate analysis, alcohol status and dose were independently associated with increased risk for earlier PancCa onset with greatest risk occurring in heavy drinkers (HR 1.62, 95% CI 1.04–2.54). Smoking status had the highest risk for earlier onset pancreatic cancer with a HR of 2.69 (95% CI, 1.97–3.68) for active smokers and independent effects for dose (P=0.019). The deleterious effects for alcohol and tobacco appear to resolve after 10 years of abstinence.CONCLUSIONS:Alcohol and tobacco use are associated with a dose-related increased risk for earlier age of onset of PancCa. Although beer drinkers develop pancreatic cancer at an earlier age than nondrinkers, alcohol type did not have a significant effect after controlling for alcohol dose.

The Effect of 96-Hour Formalin Fixation on the Immunohistochemical Evaluation of Estrogen Receptor, Progesterone Receptor, and HER2 Expression in Invasive Breast Carcinoma

We studied the impact of 96 hours of formalin fixation on estrogen receptor (ER), progesterone receptor (PR), and HER2 testing by comparing immunohistochemical results from core biopsy specimens fixed under current American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines with results for corresponding resection samples fixed for 96 hours. Samples enriched with cases showing weak to moderate receptor expression on core biopsy were included in the study. Cases were scored using ASCO/CAP guidelines. Of the 47 cases, only 1 case (2%) showed a qualitative change in result. However, this change was a positive ER result (H score, 1) on the 96-hour fixed resected sample compared with a negative ER result (H score, 0) for the core biopsy. Minimal changes in semiquantitative H scoring were noted for ER and PR that were likely due to tumor heterogeneity and/or intraobserver variability as the variation occurred in both directions. ER, PR, and HER2 immunohistochemical results should be considered valid for cases fixed up to 96 hours.

Impact of progesterone receptor semiquantitative immunohistochemical result on Oncotype DX recurrence score: a quality assurance study of 1074 cases.

Decreased or absent progesterone receptor expression in invasive breast carcinoma is a marker for an adverse prognosis. As part of an ongoing quality assurance study, this study evaluated the relationship between Oncotype DX recurrence score and progesterone receptor immunohistochemical result within each Nottingham tumor grade in 1074 cases of invasive breast carcinoma for which an Oncotype DX recurrence score was available. In addition to a statistically significant association between Nottingham grade and Oncotype DX recurrence score categories (P<0.001), an inverse relationship was identified between progesterone receptor expression measured by modified H-score semiquantitation and Oncotype DX recurrence score that was independent of Nottingham tumor grade. The Oncotype DX recurrence score relies heavily on parameters already available from routine pathologic examination, and consideration of progesterone receptor status may aid in selection of patients most likely to benefit from ancillary testing.

Stress hormones reduce the efficacy of paclitaxel in triple negative breast cancer through induction of DNA damage

Background:The mechanisms by which stress hormones impact triple-negative breast cancer (TNBC) etiology and treatment are unclear. We have previously shown that stress hormones, cortisol, and catecholamines induce rapid DNA damage and impact DNA repair in NIH 3T3 fibroblasts. This study investigates whether stress hormones increase DNA damage in breast cancer cells and if this impacts drug efficacy.Methods:We first screened a panel of 39 breast cancer cell lines for expression of adrenergic and glucocorticoid receptors and examined if stress hormones induce DNA damage and alter cell cycle regulation in vitro. A TNBC xenograft model was used to assess the impact of restraint stress on tumour growth and chemosensitivity to paclitaxel.Results:We found that stress hormones induced DNA damage, phosphorylation of ATR, which was accompanied by an up-regulation of the G1 cell kinase inhibitor p21 and a cell cycle halt of TNBCs in the G1 phase. p21 knockdown abrogated G1 arrest by stress hormones. We also demonstrated that stress significantly decreased efficacy of paclitaxel.Conclusion:We describe a novel mechanism through which stress hormones can induce drug resistance to paclitaxel, which may have profound implications for treating drug resistance in patients with TNBC.

Bright-field HER2 dual in situ hybridization (DISH) assay vs fluorescence in situ hybridization (FISH): focused study of immunohistochemical 2+ cases.

OBJECTIVES To compare the INFORM HER2 bright-field dual in situ hybridization (DISH) DNA probe cocktail assay with the PathVysion fluorescence in situ hybridization (FISH) assay on 103 invasive breast carcinomas with a 2+ score on immunohistochemistry (IHC). METHODS The cases were categorized as positive, equivocal, or negative for HER2 gene amplification using the 2007 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2:CEP17 ratio criteria and also based on mean HER2 gene copies/cell. The third criterion used a HER2:CEP17 ratio of 2 to categorize cases as positive or negative. RESULTS The agreement between FISH and DISH was 85% using the 2007 ASCO/CAP ratio criterion, 79% using the mean HER2 gene copies/cell criterion, and 92% using the 2.0 cutoff HER2:CEP17 ratio criterion. In addition, 20 known IHC 3+ breast carcinomas analyzed by DISH showed clusters of the HER2 gene consistent with unequivocal amplification. CONCLUSIONS Despite some technical and interpretational issues associated with DISH, it compares favorably with FISH in this group of challenging breast cancer cases.

Intra-tumor heterogeneity affects gene expression profile test prognostic risk stratification in early breast cancer.

Purpose: To examine the effect of intratumor heterogeneity (ITH) on detection of genes within gene expression panels (GEPs) and the subsequent ability to predict prognostic risk. Experimental Design: Multiplexed barcoded RNA analysis was used to measure the expression of 141 genes from five GEPs (Oncotype Dx, MammaPrint, PAM50, EndoPredict, and Breast Cancer Index) in breast cancer tissue sections and tumor-rich cores from 71 estrogen receptor (ER)-positive node-negative tumors, on which clinical Oncotype Dx testing was previously performed. If the tumor had foci of high Ki67 (n = 26), low/negative progesterone receptor (PR; n = 13), or both (n = 5), additional cores were obtained. In total, 181 samples were processed. Oncotype Dx recurrence scores were calculated from NanoString nCounter gene expression data. Results: Hierarchical clustering using all GEP genes showed that majority (61 of 71) of tumor samples clustered by patient, indicating greater interpatient heterogeneity (IPH) than ITH. We found a strikingly high correlation between Oncotype Dx recurrence scores obtained from whole sections versus tumor-rich cores (r = 0.94). However, high Ki67 and low PR cores had slightly higher but not statistically significant recurrence scores. For 18 of 71 (25%) patients, scores were divergent between sections and cores and crossed the boundaries for low, intermediate, and high risk. Conclusions: Our study indicates that in patients with highly heterogeneous tumors, GEP recurrence scores from a single core could under- or overestimate prognostic risk. Hence, it may be a useful strategy to assess multiple samples (both representative and atypical cores) to fully account for the ITH-driven variation in risk prediction. Clin Cancer Res; 22(21); 5362–9. ©2016 AACR.

A Role for Histone H2B Variants in Endocrine-Resistant Breast Cancer

Acquired resistance to aromatase inhibitors (AIs) remains a major clinical problem in the treatment of estrogen receptor-positive (ER+) breast cancer. We and others have previously reported widespread changes in DNA methylation using breast cancer cell line models of endocrine resistance. Here, we show that the histone variant HIST1H2BE is hypomethylated in estrogen deprivation-resistant C4-12 and long-term estrogen-deprived (LTED) cells compared with parental MCF-7 cells. As expected, this hypomethylation associates with increased expression of HIST1H2BE in C4-12 and LTED cells. Both overexpression and downregulation of HIST1H2BE caused decreased proliferation in breast cancer cell lines suggesting the need for tightly controlled expression of this histone variant. Gene expression analysis showed varied expression of HIST1H2BE in a large panel of breast cancer cell lines, without restriction to specific molecular subtypes. Analysis of HIST1H2BE messenger RNA (mRNA) expression in ER+ AI-treated breast tumors showed significantly higher expression in resistant (n = 19) compared with sensitive (n = 37) tumors (p = 0.01). Using nanostring analysis, we measured expression of all 61 histone variants in endocrine-resistant and endocrine-sensitive tumors. We found significant overexpression of 22 variant histone genes in tumors resistant to AI therapy. In silico The Cancer Genome Atlas (TCGA) analysis showed frequent amplification of the HIST1 locus. In summary, our studies show, for the first time, that overexpression of histone variants might be important in endocrine response in ER+ breast cancer, and that overexpression is at least in part mediated via epigenetic mechanisms and amplifications. Future studies addressing endocrine response should include a potential role of these currently understudied histone variants.