William E. Gillanders

EpCAM Is Overexpressed in Breast Cancer and Is a Potential Target for Breast Cancer Gene Therapy

EpCAM (epithelial cell adhesion molecule) is a cell surface molecule that is known to be highly expressed in colon and other epithelial carcinomas. EpCAM is involved in cell-to-cell adhesion and has been the target of antibody therapy in several clinical trials. To assess the value of EpCAM as a novel target for breast cancer gene therapy, we performed real-time reverse transcription-PCR to quantify the level of EpCAM mRNA expression in normal breast tissue and primary and metastatic breast cancers. We found that EpCAM is overexpressed 100- to 1000-fold in primary and metastatic breast cancer. Silencing EpCAM gene expression with EpCAM short interfering RNA (siRNA) resulted in a 35–80% decrease in the rate of cell proliferation in four different breast cancer cell lines. EpCAM siRNA treatment decreased cell migration by 91.8% and cell invasion by 96.4% in the breast cancer cell line MDA-MB-231 in vitro. EpCAM siRNA treatment was also associated with an increase in the detergent-insoluble protein fraction of E-cadherin, α-catenin, and β-catenin, consistent with the known biology of EpCAM as a regulator of cell adhesion. Our hypothesis is that modulation of EpCAM expression can affect cell migration, invasion, and proliferation by enhancing E-cadherin-mediated cell-to-cell adhesion. These data provide compelling evidence that EpCAM is a potential novel target for breast cancer gene therapy and offer insights into the mechanisms associated with EpCAM gene silencing.

Quantitative real-time RT-PCR detection of breast cancer micrometastasis using a multigene marker panel

Real‐time RT‐PCR is a relatively new technology that uses an online fluorescence detection system to determine gene expression levels. It has the potential to significantly improve detection of breast cancer metastasis by virtue of its exquisite sensitivity, high throughput capacity and quantitative readout system. To assess the utility of this technology in breast cancer staging, we determined the relative expression levels of 12 cancer‐associated genes (mam, PIP, mamB, CEA, CK19, VEGF, erbB2, muc1, c‐myc, p97, vim and Ki67) in 51 negative‐control normal lymph nodes and in 17 histopathology‐positive ALNs. We then performed a receiver operating characteristic (ROC) curve analysis to determine the sensitivity and specificity levels of each gene. Areas under the ROC curve indicated that the most accurate diagnostic markers were mam (99.6%), PIP (93.3%), CK19 (91.0%), mamB (87.9%), muc1 (81.5%) and CEA (79.4.0%). mam was overexpressed in 16 of 17 lymph nodes known to contain metastatic breast cancer at levels ranging from 22‐ to 2.8 × 105‐fold above normal mean expression, whereas PIP was overexpressed from 30‐ to 2.2 × 106‐fold above normal in 13 lymph nodes. Real‐time RT‐PCR analysis of pathology‐negative LN from breast cancer patients revealed evidence of overexpression of PIP (6 nodes), mam (3 nodes) and CEA (1 node) in 8 of 21 nodes (38%). Our results provide evidence that mam, PIP, CK19, mamB, muc1 and CEA can be applied as a panel for detection of metastatic and occult micrometastatic disease.

Defining the antigen-specific T-cell response to vaccination and poly(I:C)/TLR3 signaling: evidence of enhanced primary and memory CD8 T-cell responses and antitumor immunity.

Poly(I:C), a synthetic double-stranded RNA polymer and a TLR3 agonist, can be used as a vaccine adjuvant to enhance adaptive immunity. However, the antigen-specific CD8 T-cell response to peptide vaccination and poly(I:C) has not been clearly defined. Here, the authors characterized the antigen-specific CD8 T-cell response to peptide vaccination and poly(I:C) and specifically addressed the hypothesis that poly(I:C) can enhance antitumor immunity. To define the antigen-specific T-cell response, the authors established a model based on the adoptive transfer of T cells from the OT-1 T-cell receptor transgenic mouse. In this model, vaccination with peptide alone resulted in a limited, transient expansion of antigen-specific CD8 T cells. In contrast, peptide vaccination with concomitant administration of poly(I:C) resulted in a dramatic sustained increase in the number of antigen-specific CD8 T cells. This increase in cell number was associated with an increase in CD8 T-cell function, as defined by specific IFN-γ and TNF-α production, and protection from tumor challenge. The adjuvant effects of poly(I:C) appear to be at least partially dependent on an increase in the transcription of the anti-apoptotic molecules Bcl-3 and Bcl-xL and a concomitant decrease in apoptosis during the contraction phase of the primary T-cell response. In addition, administration of poly(I:C) enhanced the response to a nonimmunogenic self-antigen in a dendritic cell vaccine-based vaccine strategy. Collectively, these results confirm the potential of poly(I:C) as a vaccine adjuvant and suggest that targeting of TLR3 is likely to be a valuable addition to peptide-based vaccination strategies.

Molecular detection of micrometastatic breast cancer in histopathology-negative axillary lymph nodes correlates with traditional predictors of prognosis: An interim analysis of a prospective multi-institutional cohort study

Objective:We sought to establish the clinical relevance of micrometastatic disease detected by reverse transcription polymerase chain reaction (RT-PCR) in axillary lymph nodes (ALN) of breast cancer patients. Background:The presence of ALN metastases remains one of the most valuable prognostic indicators in women with breast cancer. However, the clinical relevance of molecular detection of micrometastatic breast cancer in sentinel lymph nodes (SLN) and nonsentinel ALN has not been established. Methods:Four hundred eighty-nine patients with T1–T3 primary breast cancers were analyzed in a prospective, multi-institutional cohort study. ALN were analyzed by standard histopathology (H&E staining) and by multimarker, real-time RT-PCR analysis (mam, mamB, muc1, CEA, PSE, CK19, and PIP) designed to detect breast cancer micrometastases. Results:A positive marker signal was observed in 126 (87%) of 145 subjects with pathology-positive ALN, and in 112 (33%) of 344 subjects with pathology-negative ALN. In subjects with pathology-negative ALN, a positive marker signal was significantly associated with traditional indicators of prognosis, such as histologic grade (P = 0.0255) and St. Gallen risk category (P = 0.022). Mammaglobin was the most informative marker in the panel. Conclusion:This is the first report to show that overexpression of breast cancer–associated genes in breast cancer subjects with pathology-negative ALN correlates with traditional indicators of disease prognosis. These interim results provide strong evidence that molecular markers could serve as valid surrogates for the detection of occult micrometastases in ALN. Correlation of real-time RT-PCR analyses with disease-free survival in this patient cohort will help to define the clinical relevance of micrometastatic disease in this patient population.

Isolation and molecular profiling of bone marrow micrometastases identifies TWIST1 as a marker of early tumor relapse in breast cancer patients.

Purpose: Micrometastatic cells detected in the bone marrow have prognostic significance in breast cancer. These cells are heterogeneous and likely do not exhibit uniform biological behavior. To understand the molecular diversity of disseminated cancer cells that reside in bone marrow, we enriched this cell population and did global gene expression profiling in the context of a prospective clinical trial involving women with clinical stage II/III breast cancer undergoing neoadjuvant chemotherapy. Experimental Design: Enrichment of TACSTD1 (EpCAM)–expressing cells from bone marrow of breast cancer patients was achieved using immunomagnetic beads. Gene expression profiles were compared between enriched cell populations and whole bone marrow from 5 normal volunteers and 23 breast cancer patients after neoadjuvant chemotherapy treatment. Enriched cells from bone marrow samples of breast cancer patients before treatment or at 1 year follow-up were also analyzed (total of 87 data sets). The expression of transcripts specifically detected in enriched cell populations from breast cancer patients was correlated with 1-year clinical outcome using quantitative reverse transcription-PCR in an independent cohort of bone marrow samples. Results: Analysis of EpCAM-enriched bone marrow cells revealed specific expression of a subgroup of transcripts, including the metastasis regulator, TWIST1. Most transcripts identified, including TWIST1, were not expressed in enriched populations of bone marrow from normal volunteers, suggesting that this expression profile reflects a signature of breast cancer bone marrow micrometastases that persist after chemotherapy. In an independent set of bone marrow samples obtained before any treatment, TWIST1 expression correlated with early disease relapse. Conclusions: Disseminated breast cancer cells present in bone marrow after chemotherapy possess unique transcriptional signatures. Genes whose expression is overrepresented in these cell populations, such as TWIST1, may prove to be excellent markers of early distant relapse in breast cancer patients.

Defining the ability of cyclophosphamide preconditioning to enhance the antigen-specific CD8+ T-cell response to peptide vaccination: creation of a beneficial host microenvironment involving type I IFNs and myeloid cells.

Although cyclophosphamide (CTX) has been clearly shown to enhance active specific and adoptive immunotherapies, the mechanism(s) underlying these beneficial effects have not been clearly defined. To define the impact of CTX preconditioning on the antigen-specific CD8 T-cell response to peptide vaccination, we used an adoptive transfer model based on the OT-1 T-cell receptor transgenic mouse. CTX preconditioning dramatically enhanced the antigen-specific CD8 T-cell response to peptide vaccination. Specifically, CTX significantly enhanced the expansion and function of responding CD8 T cells as demonstrated by flow cytometry and cytokine production. In parallel experiments, we attempted to define the mechanism(s) underlying these beneficial effects of CTX therapy. CTX therapy increased the relative number and activation status of myeloid dendritic cells, and was associated with the induction of significant levels of the inflammatory cytokines interferon-α, monocyte chemoattractant protein-1, and IL-6. Adoptive transfer experiments into type I IFNR−/− and CR3−/− mice confirmed that the beneficial effects of CTX were at least partially dependent on type I interferons and myeloid cells. Adoptive transfer of up to 150×106 naive spleen cells at the time of antigen-specific CD8 T-cell transfer did not abrogate the effects of CTX therapy, suggesting that the creation of a niche in the immune system may not be required. CTX decreased the absolute, but not relative number of CD4+CD25+ Treg cells, consistent with the possibility that regulatory T cells may be targeted by CTX therapy. Of note, combination therapy with CTX and a synthetic TLR3 agonist further enhanced the antigen-specific CD8+ T-cell response. Taken together, our data suggest that CTX modulates specific components of the innate immune system resulting in a beneficial host microenvironment. Specific targeting of these components may enhance the effectiveness of CTX preconditioning for adoptive immunotherapy.

Systemic Administration of IL-15 Augments the Antigen-Specific Primary CD8+ T Cell Response Following Vaccination with Peptide-Pulsed Dendritic Cells

The systemic administration of IL-2 can act as a potent adjuvant for T cell-directed vaccine strategies. However, not only is the administration of IL-2 potentially toxic, but recent evidence suggests that it may also paradoxically limit the duration and magnitude of the cytotoxic T cell response. A recently identified cytokine, IL-15, shares many properties with IL-2 and may provide a preferential means of augmenting T cell-directed vaccine responses. Although well characterized in vitro, there are few data on the ability of IL-15 to augment T cell-mediated responses in vivo. We therefore evaluated the ability of systemic IL-15 to function as a T cell adjuvant in a murine vaccine model. To establish a population of easily identifiable Ag-responsive T cells, naive CD8+ (OT-1) T cells were first adoptively transferred into mice. Vaccination with peptide-pulsed dendritic cells induced a modest expansion of OT-1 T cells. The addition of systemic IL-15 for 7 days following vaccination resulted in a significant increase in the expansion of responding T cells in the PBL, spleen, and lymph nodes. Importantly, the responding T cells were cytotoxic and maintained a Tc1-biased phenotype. We did not observe either enhanced resistance to activation-induced cell death or preferential generation of memory T cells as a result of treatment with IL-15 compared with IL-2. These studies show for the first time that IL-15 is capable of augmenting the primary CD8+ T cell response to vaccination and contribute to the basis for future experiments exploring the clinical role of IL-15.

Duodenopancreatic resections in patients with multiple endocrine neoplasia type 1.

OBJECTIVEnTo review the authors 7-year experience with a surgical approach for pancreatic and duodenal neuroendocrine tumors (NETs) in patients with multiple endocrine neoplasia type 1 (MEN 1) designed to remove all gross tumor with limited complications, preserving pancreatic function.nnnSUMMARY BACKGROUND DATAnMEN 1 is an autosomal dominant familial neoplasia syndrome characterized by the development of NETs of the duodenum and pancreas. Some tumors are clinically insignificant or follow a benign course, although a subset pursues a malignant, lethal natural history; the risk of surgical management must be appropriate to the disease course.nnnMETHODSnThe clinical, biochemical, genetic, and pathologic data were retrospectively reviewed for 21 consecutive MEN 1 patients undergoing pancreatic resection for NETs between 1993 and 1999 at one institution. Age at operation, presenting symptoms, results of preoperative and intraoperative localization studies, major and minor complications, and pathology, including metastases, were analyzed.nnnRESULTSnThe surgical approach was selected based on the location and size of the tumors. Five patients required pancreaticoduodenectomy, 11 patients underwent non-Whipple pancreatic resections, and 5 underwent simple enucleation of benign NETs. The incidence of regional lymph node metastases was 33%.nnnCONCLUSIONSnMajor pancreatic procedures can be performed safely in most patients with MEN 1 and NETs. Because NETs are the most common MEN 1-related cause of death in the authors kindreds, an aggressive surgical approach, including early intervention before malignant spread and major pancreatic resection where indicated, appears justified.

A Rapid, Fully Automated, Molecular-Based Assay Accurately Analyzes Sentinel Lymph Nodes for the Presence of Metastatic Breast Cancer

Objective:To develop a fully automated, rapid, molecular-based assay that accurately and objectively evaluates sentinel lymph nodes (SLN) from breast cancer patients. Summary Background Data:Intraoperative analysis for the presence of metastatic cancer in SLNs from breast cancer patients lacks sensitivity. Even with immunohistochemical staining (IHC) and time-consuming review, alarming discordance in the interpretation of SLN has been observed. Methods:A total of 43 potential markers were evaluated for the ability to accurately characterize lymph node specimens from breast cancer patients as compared with complete histologic analysis including IHC. Selected markers then underwent external validation on 90 independent SLN specimens using rapid, multiplex quantitative reverse transcription-polymerase chain reaction (QRT-PCR) assays. Finally, 18 SLNs were analyzed using a completely automated RNA isolation, reverse transcription, and quantitative PCR instrument (GeneXpert). Results:Following analysis of potential markers, promising markers were evaluated to establish relative level of expression cutoff values that maximized classification accuracy. A validation set of 90 SLNs from breast cancer patients was prospectively characterized using 4 markers individually or in combinations, and the results compared with histologic analysis. A 2-marker assay was found to be 97.8% accurate (94% sensitive, 100% specific) compared with histologic analysis. The fully automated GeneXpert instrument produced comparable and reproducible results in less than 35 minutes. Conclusions:A rapid, fully automated QRT-PCR assay definitively characterizes breast cancer SLN with accuracy equal to conventional pathology. This approach is superior to intraoperative SLN analysis and can provide standardized, objective results to assist in pathologic diagnosis.

Transcriptional repression of epithelial cell adhesion molecule contributes to p53 control of breast cancer invasion.

p53 is a tumor suppressor gene with well-characterized roles in cell cycle regulation, apoptosis, and maintenance of genome stability. Recent evidence suggests that p53 may also contribute to the regulation of migration and invasion. Epithelial cell adhesion molecule (EpCAM) is a transmembrane glycoprotein that is overexpressed in the majority of human epithelial carcinomas, including breast and colorectal carcinomas. We show by chromatin immunoprecipitation assays that p53 interacts with a candidate p53 binding site within the EpCAM gene. p53-mediated transcriptional repression of EpCAM was confirmed in gain-of-function and loss-of-function experimental systems. Induction of wild-type p53 was associated with a significant dose-dependent decrease in EpCAM expression; conversely, specific ablation of p53 was associated with a significant increase in EpCAM expression. At the functional level, specific ablation of p53 expression is associated with increased breast cancer invasion, and this effect is abrogated by concomitant specific ablation of EpCAM expression. Taken together, these biochemical and functional data are the first demonstration that (a) wild-type p53 protein binds to a response element within the EpCAM gene and negatively regulates EpCAM expression, and (b) transcriptional repression of EpCAM contributes to p53 control of breast cancer invasion.