Breast cancer-derived M543V mutation in helix 12 of estrogen receptor alpha inverts response to estrogen and SERMs.

We have isolated from human breast cancers several mutations in the Helix 12 component of activation function 2 (AF-2) in the estrogen receptor alpha (ERalpha). We used a novel approach to detect changes in the hormone-binding domain of ERalpha, based on the evidence that antiestrogens, such as 4-hydroxytamoxifen (ZOHT) and ICI 182,780, block the function of ERalpha by binding and folding the AF-2 transcriptional domain in a way that inhibits its association with coactivator proteins. We have identified a Helix 12 mutation, M543V, which leads to greater ERalpha transcription with ZOHT and other antiestrogens (including 1,1-dichloro-2,2,3-triarylcyclopropanes, DTACs) than with 17-beta estradiol (E2). We also found an independent mutation at the same position, M543I, which did not show this inverted ligand phenotype. In comparison to further Helix 12 mutations made in vitro, it appears that relative hydrophobicity of the amino acid side chains on the inner face of Helix 12 is key to maintaining the transcriptionally active, agonist conformation with bound E2. This active conformation can be induced, resulting in increased transcription, by adding excess p160 coactivator AIB1 in transcriptional assays with E2-bound receptors, while the ZOHT-bound receptors were not further activated by AIB1. Other experiments show that the cross talk between ERalpha and AP-1 protein from AP-1-binding sites is not dependent on Helix 12 integrity. We show that two alleles containing a proline substitution in Helix 12 that inactivate AF-2 function of ERalpha at EREs have little negative effect on function through AP-1 elements, supporting a prominent role for the N-terminal AF-1 of ERalpha in AP-1/ERalpha transcriptional cross talk.

Focal radiation fibrosis after radioimmunotherapy for follicular non-Hodgkin lymphoma.

A 75-year-old man with relapsed follicular non-Hodgkin lymphoma confined to a solitary lung mass was treated with radioimmunotherapy (RIT) using yttrium 90-ibritumomab tiuxetan. Imaging with positron emission tomography/computed tomography showed a complete response 3 months after RIT. Thirteen months after RIT, his positron emission tomography/computed tomography scan showed a fluorodeoxyglucose-avid infiltrate in the area of the previous lung mass. Bronchoscopy revealed the area to be obstructed with fibrosis, and cytologic washings and brushings did not show lymphoma. The patient remains asymptomatic, and the fluorodeoxyglucoseavid pulmonary infiltrate was unchanged 19 months after RIT. In view of the lack of respiratory symptoms or progressive imaging abnormalities, we believe radiation fibrosis is the most likely etiology. Radiation-induced lung injury after therapy with yttrium 90 was previously reported in the setting of intraarterial microspheres used to treat inoperable hepatic tumors. This is the first case in which radiation-induced radiographic changes are reported after RIT for lymphoma.

Comprehensive genome and transcriptome analysis of the 11q13 amplicon in human oral cancer and synteny to the 7F5 amplicon in murine oral carcinoma.

11q13 amplification occurs in a wide variety of tumors, including almost half of oral squamous cell carcinomas (OSCC) where it has been correlated with a poor outcome. In this study, we compiled 3.6 Mb of DNA sequence in the 11q13 amplicon core and refined the physical map of the amplicon. In the process, we determined the genomic structure and normal tissue expression patterns of two recently identified genes, TAOS2/TMEM16A and MRGF, which reside in the amplicon core. We then quantified DNA copy number and mRNA expression of all genes in the 11q13 amplicon in cell lines and primary tumors from OSCC. With the exception of FGF3, FGF4, FGF19, and MRGF, all genes were overexpressed in most tumors with genomic amplification. Furthermore, we found that the expression of genes in the amplicon appeared to be highly coordinated, making it difficult to determine which gene or genes are driving amplification. However, in nonamplified primary tumors, three genes, TAOS2/TMEM16A, OCIM, and TPCN2, are frequently overexpressed, whereas CCND1 and EMS1 are not. These results suggest that in addition to CCND1 and EMS1, other important genes also may be target genes driving 11q13 amplification. We hypothesize that 11q13 amplification may be driven by a cassette of genes that provide growth or metastatic advantage to cancer cells. This is supported by the finding that the human 11q13 amplicon core is syntenic to mouse chromosomal band 7F5, which is frequently amplified in chemically induced murine OSCC. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat

Technology for automated, rapid, and quantitative PCR or reverse transcription-PCR clinical testing.

BACKGROUND: PCR-based assays can improve clinical care, but they remain technically demanding and labor-intensive. We describe a new instrument, the GeneXpert, that performs automated nucleic acid isolation, reverse transcription, and fluorescence-based quantitative PCR in approximately 35 min. METHODS: Yield and integrity of RNA isolated on the GeneXpert were compared with Qiagen-based extraction for parallel samples (5-microm frozen tissue sections). The reproducibility of automated RNA isolation, reverse transcription, and quantitative PCR was determined by replicate (n = 10) analysis of 10 tissues, using duplex (target and endogenous control) reverse transcription-PCR reactions for two gene combinations. The GeneXpert was then used to perform rapid analysis of lymph nodes from melanoma, breast cancer, and lung cancer patients and analysis of melanoma metastatic to the lung, primary lung adenocarcinoma, and healthy lung tissue. RESULTS: On the GeneXpert, RNA was recovered in slightly over 6 min, and the yield was approximately 70% of that from parallel Qiagen reactions. The RNA integrity was comparable to that of Qiagen-isolated RNA as determined by gel electrophoresis. For the melanoma samples, the 95% prediction interval for the deltaCt for a new measurement was +/-1.54 cycles, and for breast cancer samples, the interval for a newly observed deltaCt was +/-1.40 cycles. GeneXpert assays successfully detected the presence of metastatic melanoma, breast cancer, and lung cancer in lymph nodes and also differentiated among metastatic melanoma, lung adenocarcinoma, and healthy lung. CONCLUSIONS: RNA yield and integrity on the GeneXpert are comparable to benchtop methods. Reproducibility of the GeneXpert data is similar to that seen with manual methods in our hands but may need improvement for some applications. The GeneXpert can perform RNA isolation, reverse transcription, and quantitative PCR in approximately 35 min and could therefore be used for intraoperative testing when applicable.

Inhibition of estrogen receptor alpha-mediated transcription by antiestrogenic 1,1-dichloro-2,2,3-triarylcyclopropanes.

A novel class of pure antiestrogens, 1,1-dichloro-2,2,3-triarylcyclopropanes (DTACs), lack estrogenic activity in a mouse uterotrophic assay and inhibit the growth of estrogen-sensitive MCF-7 breast cancer cells (Day et al., 1991). Here, reporter assays were used to evaluate the effects of the DTACs on estrogen receptor alpha (ERalpha)-mediated transcription from either classic estrogen-response elements (EREs) or nonclassic AP-1 elements. Among the DTACs tested, only the compounds with smaller aromatic substituents, BDRM72 and BDRM81, displayed weak agonist activity on EREs. Their activity was less than that observed for the ER partial agonist, 4-hydroxytamoxifen (ZOHT). In competition experiments, the DTACs blocked estradiol-stimulated transcription from an ERE in a dose-dependent manner and were more effective inhibitors than ZOHT. Each of the DTACs was significantly less active than ZOHT or the pure antiestrogen ICI 182,780 (faslodex) in stimulating transcription from nonclassic AP-1 elements in the presence of ERalpha. DTACs did not modulate either basal or TPA (12-O-tetradecanoylphorbol-13-acetate)-stimulated transcription from an AP-1 element in the absence of ERalpha, indicating that they are not nonspecific inhibitors of transcription and that ERalpha is the drug target. Glutathione S-transferase pull-down assays were used to examine whether DTACs alter the interaction between ERalpha and the p160 coactivator, GRIP1. BDRM35, which has the same dimethylaminomethoxy and phenolic moieties as ZOHT, reduced binding by more than 50%. Thus, disruption of p160 coactivator recruitment by ERalpha may represent one mechanism by which DTACs function as antiestrogens. BDRM35 also suppresses estradiol induction of endogenous target genes c-myc and cyclin D1 in MCF-7 breast cancer cells.

Functional mutations of estrogen receptor protein: assay for detection.

Antiestrogens block the function of estrogen receptor (ER) by binding and misfolding the AF-2 transcriptional activation region in the ligand-binding domain, inhibiting or altering its association with coactivator proteins. We describe a novel assay uniquely configured to identify aberrations in this function that may lead to antiestrogen resistance. The identification of mutations of ER that affect its function is important to current breast cancer therapies. Standard methods to detect these mutations are cumbersome and the number of described mutations is limited, reflecting this difficulty. Conventional ER analysis in the clinic demonstrates the presence of antigenic determinants of the receptor protein or estrogenic ligand binding without reflection on the critical ability of the liganded receptor to interact with transcription cofactors. Here, we describe the use of estrogenic regulation of a site-specific recombinase activity, measuring deletion of a color marker gene via FLP-ER fusion proteins, to detect functional changes in ER protein folding that affects the site where cofactors interact. The assay provides a method to readily detect single amino acid changes in ER, some with biologically important consequences. Without such a functional assay as described, phenotypic changes are likely to remain undetected and under-evaluated. It is probable that some human tumors have antihormone resistance resulting from ER mutations that either block antihormone binding or transmit antihormone binding as a positive transcriptional signal via cofactor interaction. An assay to evaluate functional ER will lead to better predictive tests of treatment modalities.