Ductal lavage is an inefficient method of biomarker measurement in high-risk women

Effective methods of serial epithelial sampling to measure breast-specific biomarkers will aid the rapid evaluation of new preventive interventions. We report here a proof-of-principle phase 2 study to assess the utility of ductal lavage (DL) to measure biomarkers of tamoxifen action. We enrolled women with a 5-year breast cancer risk estimate >1.6% or the unaffected breast of women with T1a or T1b breast cancer. After entry DL, participants chose tamoxifen or observation and underwent repeat DL 6 months later. Samples were processed for cytology and immunohistochemistry for estrogen receptor alpha, Ki-67, and cyclooxygenase-2. Of 182 women recruited, 115 (63%) underwent entry and repeat DL; 85 (47%) had sufficient cells for analysis from > or =1 duct at both time points; in 78 (43%), cells were sufficient from > or =1 matched ducts. Forty-six women chose observation and 39 chose tamoxifen. We observed greater reductions in the tamoxifen group than in the observation group for Ki-67 (adjusted P = 0.03) and estrogen receptor alpha (adjusted P = 0.07), but not in cyclooxygenase-2 (adjusted P = 0.4) labeling. Cytologic findings showed a trend toward improvement in the tamoxifen group compared with the observation group. Interobserver variability for cytologic diagnosis between two observers showed good agreement (kappa = 0.44). Using DL, we observed the expected changes in tamoxifen-related biomarkers; however, poor reproducibility of biomarkers in the observation group, the 53% attrition rate of subjects from recruitment to biomarker analyses, and the expense of DL are significant barriers to the use of this procedure for biomarker assessment over time.

Serial ductal lavage for biomarker assessment in a phase 2 prevention study with tamoxifen

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Background: Effective methods of epithelial sampling to measure breast-specific biomarkers will aid the rapid evaluation of new preventive interventions. We report a proof-of-principle Phase 2 study to assess the utility of ductal lavage (DL) to measure biomarkers using tamoxifen (TAM) as the gold standard prevention agent. Methods: We enrolled women with a 5-year Gail risk >1.6 or the unaffected breast of women with breast cancer =1 cm. After entry DL, participants chose TAM or observation (OBS), and underwent repeat DL 6 months later. Samples were processed for cytology and immunohistochemistry for ER and Ki-67 labeling indices (LIs). If =1 duct showed atypia, the sample was called atypical. LI data were analyzed by duct (comparing the same duct at 2 time points) and by woman (comparing the mean of all ducts at 2 time points). Results: Of 168 women recruited, 135 (80%) underwent entry and repeat DL; 82 (49%) had sufficient cells for analysis at both time points (mean age 50 years, mean Gail 3.0). 44 chose observation and 38 chose TAM. Cytologic findings, by woman and by duct, showed significantly greater net improvement (from atypical to benign) in the TAM than in the OBS group (see table ). The repeat ER and Ki-67 LIs showed a significant reduction from entry within the TAM group (p=0.01 and 0.0001, respectively), but not in the OBS group when analysed by duct. Similarly, in analyses by woman, the ER and Ki-67 LIs decreased from entry to repeat DL within the TAM group (p=0.046 and 0.004 respectively), with minimal changes in the observation group. Between-group data are shown in the table and are similar to the within- group differences. Conclusions: Using DL, we saw the expected changes in TAM-related biomarkers, with stronger reductions in duct-to- duct comparisons than when findings were averaged across ducts in individual women. However, the 51% attrition rate of subjects from recruitment to biomarker analyses, along with the expense of DL, raises questions regarding the efficiency of this procedure in biomarker assessment over time.

[Table: see text]

No significant financial relationships to disclose.

Endocrine biomarkers in ductal lavage samples from women at high risk for breast cancer

BACKGROUND

Ductal lavage is a method of minimal epithelial sampling of the breast, with potential utility for repeat sampling and biomarker analysis in chemoprevention studies. We report here the baseline findings from a study designed to assess the utility of ductal lavage in this setting.

METHODS

Tamoxifen-eligible, high-risk women underwent ductal lavage; epithelial cell number (ECN) and morphology were assessed on Papanicolaou-stained slides. Additional slides were immunostained for estrogen receptor (ER) alpha, Ki-67, and cyclooxygenase-2, and the labeling index (LI) was established by counting negative and positive cells. The ductal lavage supernatant (DLS) was assayed for estradiol, several of its precursors, progesterone, cathepsin D, interleukin-6, and epidermal growth factor (EGF).

RESULTS

One hundred sixty-eight women have entered the study (mean age, 51 years; mean 5-year Gail score, 2.8). Ductal lavage was accomplished in 145 (86.3%) women. Data were analyzed by duct and by woman (averaging data across all ducts). Mild atypia was seen in 43 of 145 (29.6%), whereas severe atypia was seen in 2 (1.4%) of women. We observed significant positive correlations between ECN and cytologic atypia, ER LI, cyclooxygenase-2 LI, and Ki-67 LI. EGF levels in supernatant were significantly associated with estrogenic precursors, ER LI and ECN. A factor representing the DLS hormone and protein variables explained 36% of the variance; total ECN was highest when factor score and ER LI were high and was lowest when both were low (P for interaction = 0.001).

CONCLUSIONS

Biomarker analyses in epithelial cells and DLS are feasible. The significant associations of EGF with other markers suggest a possible role in increasing epithelial cell mass.

Ductal lavage findings in women with mammographic microcalcifications undergoing biopsy

BACKGROUND

We designed a prospective study to assess the likelihood that early lesions presenting as mammographic calcifications could be accessed for cytological diagnosis by ductal lavage (DL).

METHODS

Consenting women with calcifications (Breast Imaging Reporting and Data System 4 or 5) underwent DL of fluid-yielding ducts (FYDs) before stereotactic core or excisional biopsy. The DL catheter was used to inject .2 to 1 mL of Isovue 300 into the duct to determine whether the FYD corresponded to the duct containing calcifications (designated overlap). Additional FYDs were injected, if possible, until overlap was identified. DL cytology was compared with histology.

RESULTS

Twenty women were enrolled (mean age, 54.2 years); the mean size of the calcification-bearing area was 190 mm(2). The histological findings were as follows: 1 invasive cancer, 9 ductal carcinomas-in-situ (DCIS), 5 atypical hyperplasias, and 5 usual hyperplasias or fibrocystic changes. Four women had no FYD. In 15 women who underwent DL and ductography, overlap of dye and calcifications was seen in 4 (27%): 1 fibrocystic change, 1 hyperplasia, 1 atypical hyperplasia (cytological diagnosis mildly atypical), and 1 DCIS (cytological diagnosis benign). Of the remaining 8 DCIS lesions, 4 had no nipple aspiration fluid, 1 showed extravasation, and 3 were lavaged but the duct did not overlap.

CONCLUSIONS

These results are consistent with data from women undergoing mastectomy for larger invasive cancer and DCIS and show that cancer-containing ducts do not yield nipple fluid in most cases.

Ductal lavage findings in women with known breast cancer undergoing mastectomy

BACKGROUND

Ductal lavage has the potential to detect cancer by sampling breast epithelium in asymptomatic high-risk women. To assess the utility of ductal lavage as a cancer diagnostic test, we investigated the association between ductal lavage cytologic findings and histologic findings in women with known breast cancer undergoing mastectomy.

METHODS

Ductal lavage was performed in the operating room before mastectomy on 44 breasts from 32 women with known cancer and on eight breasts from seven women undergoing prophylactic mastectomy, two with occult malignancy. If the ductal lavage sample from one or more ducts contained enough epithelial cells for a cytologic diagnosis, lavaged ducts were injected with a mixture of colored dye, gelatin, and a radiographic contrast compound after mastectomy, and breast tissue was radiographed and sectioned. Histologic findings in ducts with and without dye were recorded. Associations between cytologic results and histologic results were examined by univariate and multivariable analyses.

RESULTS

At least one duct was lavaged in 36 breasts (mean = 1.4 ducts per breast); all histologic and cytologic procedures were completed in 28 breasts and in 39 ducts. Markedly atypical or malignant cytology was found in five cancer-containing breasts. In 39 ducts with complete cytologic and histologic data and when marked atypia or malignant cells defined a positive cytologic test, sensitivity was 43% (95% confidence interval [CI] = 23% to 72%), specificity was 96% (95% CI = 86% to 100%), and accuracy was 77% (95% CI = 63% to 89%). When mild or marked atypia or malignant cells defined a positive cytologic test, sensitivity was 79% (95% CI = 57% to 96%), specificity was 64% (95% CI = 46% to 83%), and accuracy was 69% (95% CI = 55% to 83%). When all 31 cytologically evaluable breasts were analyzed, sensitivity was 17% (95% CI = 7% to 35%), specificity was 100% (95% CI = 5% to 100%), and accuracy was 19% (95% CI = 9% to 38%).

CONCLUSION

In breasts with cancer, ductal lavage appears to have low sensitivity and high specificity for cancer detection, possibly because cancer-containing ducts fail to yield fluid or have benign or mildly atypical cytology.

Histone H3 lysine 4 methylation is mediated by Set1 and required for cell growth and rDNA silencing in Saccharomyces cerevisiae

Histone methylation is known to be associated with both transcriptionally active and repressive chromatin states. Recent studies have identified SET domain-containing proteins such as SUV39H1 and Clr4 as mediators of H3 lysine 9 (Lys9) methylation and heterochromatin formation. Interestingly, H3 Lys9 methylation is not observed from bulk histones isolated from asynchronous populations of Saccharomyces cerevisiae or Tetrahymena thermophila. In contrast, H3 lysine 4 (Lys4) methylation is a predominant modification in these smaller eukaryotes. To identify the responsible methyltransferase(s) and to gain insight into the function of H3 Lys4 methylation, we have developed a histone H3 Lys4 methyl-specific antiserum. With this antiserum, we show that deletion of SET1, but not of other putative SET domain-containing genes, in S. cerevisiae, results in the complete abolishment of H3 Lys4 methylation in vivo. Furthermore, loss of H3 Lys4 methylation in a set1 Delta strain can be rescued by SET1. Analysis of histone H3 mutations at Lys4 revealed a slow-growth defect similar to a set1 Delta strain. Chromatin immunoprecipitation assays show that H3 Lys4 methylation is present at the rDNA locus and that Set1-mediated H3 Lys4 methylation is required for repression of RNA polymerase II transcription within rDNA. Taken together, these data suggest that Set1-mediated H3 Lys4 methylation is required for normal cell growth and transcriptional silencing.

The Sgs1 helicase of Saccharomyces cerevisiae inhibits retrotransposition of Ty1 multimeric arrays

Ty1 retrotransposons in the yeast Saccharomyces cerevisiae are maintained in a genetically competent but transpositionally dormant state. When located in the ribosomal DNA (rDNA) locus, Ty1 elements are transcriptionally silenced by the specialized heterochromatin that inhibits rDNA repeat recombination. In addition, transposition of all Ty1 elements is repressed at multiple posttranscriptional levels. Here, we demonstrate that Sgs1, a RecQ helicase required for genome stability, inhibits the mobility of Ty1 elements by a posttranslational mechanism. Using an assay for the mobility of Ty1 cDNA via integration or homologous recombination, we found that the mobility of both euchromatic and rDNA-Ty1 elements was increased 32- to 79-fold in sgs1Delta mutants. Increased Ty1 mobility was not due to derepression of silent rDNA-Ty1 elements, since deletion of SGS1 reduced the mitotic stability of rDNA-Ty1 elements but did not stimulate their transcription. Furthermore, deletion of SGS1 did not significantly increase the levels of total Ty1 RNA, protein, or cDNA and did not alter the level or specificity of Ty1 integration. Instead, Ty1 cDNA molecules recombined at a high frequency in sgs1Delta mutants, resulting in transposition of heterogeneous Ty1 multimers. Formation of Ty1 multimers required the homologous recombination protein Rad52 but did not involve recombination between Ty1 cDNA and genomic Ty1 elements. Therefore, Ty1 multimers that transpose at a high frequency in sgs1Delta mutants are formed by intermolecular recombination between extrachromosomal Ty1 cDNA molecules before or during integration. Our data provide the first evidence that the host cell promotes retrotransposition of monomeric Ty1 elements by repressing cDNA recombination.

My mother caused my illness: the story of a survivor of Münchausen by proxy syndrome

OBJECTIVE

Münchausen by proxy syndrome (MBPS) is a form of child abuse in which a parent fabricates or produces illness in a child. Although the medical consequences of MBPS have been well described, there is no detailed published account of what it was like to grow up in a family where the mother systematically induced serious illness. This article describes one victim's childhood experiences.

METHODS

The medical history was obtained from a review of the original medical records, notes from the primary physician, discussions with two physicians who provided treatment, and several meetings with the victim and the victim's therapist.

RESULTS

This article chronicles the actual experiences of an MBPS victim through 8 years of medical abuse at the hands of her mother, reveals the victim's account of what happened to her, describes what her family was like, details the long-term consequences on emotional and physical development, identifies the factors that influence recovery, and details the impact on family relationships.

CONCLUSIONS

Child maltreatment and MBPS need to be part of the differential diagnosis when the clinical picture is atypical or does not appear medically plausible. The consequences of MBPS are psychological and physical and impact the entire family. Suggestions to assist heath care providers recognize, assess, and report cases of suspected MBPS are provided.

Transcriptional silencing of Ty1 elements in the RDN1 locus of yeast

We demonstrate that in Saccharomyces cerevisiae, the tandem array of ribosomal RNA genes (RDN1) is a target for integration of the Ty1 retrotransposon that results in silencing of Ty1 transcription and transposition. Ty1 elements transpose into random rDNA repeat units and are mitotically stable. In addition, we have found that mutation of several putative modifiers of RDN1 chromatin structure abolishes silencing of Ty1 elements in the rDNA array. Disruption of SIR2, which elevates recombination in RDN1, or TOP1, which increases psoralen accessibility in rDNA, or HTA1-HTB1, which reduces histone H2A-H2B levels and causes localized chromatin perturbations, abolishes transcriptional silencing of Ty1 elements in RDN1. Furthermore, deletion of the gene for the ubiquitin conjugating enzyme Ubc2p, which ubiquitinates histones in vitro, derepresses not only Ty1 transcription but also mitotic recombination in RDN1. On the basis of these results, we propose that a specialized chromatin structure exists in RDN1 that silences transcription of the Ty1 retrotransposon.

Intron-encoded endonuclease I-TevI binds as a monomer to effect sequential cleavage via conformational changes in the td homing site

I-TevI, the intron-encoded endonuclease from the thymidylate synthase (td) gene of bacteriophage T4, binds its DNA substrate across the minor groove in a sequence-tolerant fashion. We demonstrate here that the 28 kDa I-TevI binds the extensive 37 bp td homing site as a monomer and significantly distorts its substrate. In situ cleavage assays and phasing analyses indicate that upon nicking the bottom strand of the td homing site, I-TevI induces a directed bend of 38 degrees towards the major groove near the cleavage site. Formation of the bent I-TevI-DNA complex is proposed to promote top-strand cleavage of the homing site. Furthermore, reductions in the degree of distortion and in the efficiency of binding base-substitution variants of the td homing site indicate that sequences flanking the cleavage site contribute to the I-TevI-induced conformational change. These results, combined with genetic, physical and computer-modeling studies, form the basis of a model, wherein I-TevI acts as a hinged monomer to induce a distortion that widens the minor groove, facilitating access to the top-strand cleavage site. The model is compatible with both unmodified DNA and glucosylated hydroxymethylcytosine-containing DNA, as exists in the T-even phages.

Selection of a remote cleavage site by I-tevI, the td intron-encoded endonuclease

I-TevI, a double-strand DNA endonuclease involved in the mobility of the td intron of phage T4, is highly unusual in that it binds and cleaves intronless td alleles (td homing sites) in a site-specific but sequence-tolerant manner. The endonuclease binds to sequences flanking the intron insertion site and near the remote cleavage site, located 23 and 25 nucleotides away on the top and bottom strands, respectively. Mapping studies indicate that I-TevI has both sequence and distance sensors that function during cut-site selection. Although I-TevI cleavage of many insertion and deletion variants of the homing site is impaired, double-strand breaks are generated at positions that collectively span two turns of the helix, indicating that the interaction is extraordinarily flexible. However, the endonuclease does exhibit spacing preferences between its binding domains, and sequence preferences near the cleavage site, with the G:C pair at -23 implicated as a cleavage determinant. Furthermore, I-TevI appears to function through interactions across the minor groove at the cleavage site, as it does at the intron insertion site, and to be capable of cleaving sequentially, first on the bottom and then on the top strand. These properties of I-TevI are incorporated in a model wherein the endonuclease effects distant cleavage via a flexible hinge.

The td intron endonuclease I-TevI makes extensive sequence-tolerant contacts across the minor groove of its DNA target

I-TevI, a double-strand DNA endonuclease encoded by the mobile td intron of phage T4, has specificity for the intronless td allele. Genetic and physical studies indicate that the enzyme makes extensive contacts with its DNA substrate over at least three helical turns and around the circumference of the helix. Remarkably, no single nucleotide within a 48 bp region encompassing this interaction domain is essential for cleavage. Although two subdomains (DI and DII) contain preferred sequences, a third domain (DIII), a primary region of contact with the enzyme, displays much lower sequence preference. While DII and DIII suffice for recognition and binding of I-TevI, all three domains are important for formation of a cleavage-competent complex. Mutational, footprinting and interference studies indicate predominant interactions of I-TevI across the minor groove and phosphate backbone of the DNA. Contacts appear not to be at the single nucleotide level; rather, redundant interactions and/or structural recognition are implied. These unusual properties provide a basis for understanding how I-TevI recognizes T-even phage DNA, which is heavily modified in the major groove. These recognition characteristics may increase the range of natural substrates available to the endonuclease, thereby extending the invasive potential of the mobile intron.

I-TevI, the endonuclease encoded by the mobile td intron, recognizes binding and cleavage domains on its DNA target

Mobility of the phage T4 td intron depends on activity of an intron-encoded endonuclease (I-TevI), which cleaves a homologous intronless (delta In) target gene. The double-strand break initiates a recombination event that leads to intron transfer. We found previously that I-TevI cleaves td delta In target DNA 23-26 nucleotides upstream of the intron insertion site. DNase I-footprinting experiments and gel-shift assays indicate that I-TevI makes primary contacts around the intron insertion site. A synthetic DNA duplex spanning the insertion site but lacking the cleavage site was shown to bind I-TevI specifically, and when cloned, to direct cleavage into vector sequences. The behavior of the cloned duplex and that of deletion and insertion mutants support a primary role for sequences surrounding the insertion site in directing I-TevI binding, conferring cleavage ability, and determining cleavage polarity. On the other hand, sequences around the cleavage site were shown to influence cleavage efficiency and cut-site selection. The role of cleavage-site sequences in determining cleavage distance argues against a strict "ruler" mechanism for cleavage by I-TevI. The complex nature of the homing site recognized by this unusual type of endonuclease is considered in the context of intron spread.

Spontaneous shuffling of domains between introns of phage T4

The three self-splicing introns in phage T4 (in the td, sunY and nrdB genes) (Fig. 1a) each have the conserved group I catalytic RNA core structure (Fig. 1b), out of which is looped an open reading frame. Although the core sequences are very similar (approximately 60% identity), the open reading frames seem to be unrelated. Single crossover recombination events between homologous core sequences in the closely linked td and nrdB introns have led to 'exon shuffling. Here we describe spontaneous double crossovers between the unlinked td and sun Y introns that result in shuffling of an intron structure element, P7.1 (refs 3 and 4). The intron domain-switch variants were isolated as genetic suppressors of a splicing-defective P7.1 deletion in the td intron. This unprecedented example of suppression through inter-intron sequence substitution indicates that the introns are in a state of genetic flux and implies the functional interchangeability of the two analogous but nonidentical P7.1 elements. The implications of such recombination events are discussed in the light of the evolution of the introns themselves as well as that of their host genomes.