Defining the decision-to-delivery interval at caesarean section: narrative literature review and proposal for standardisation

The decision-to-delivery interval is a widely used term at non-elective caesarean section. While the definition may appear self-evident, there is no universally agreed consensus about when this period begins and ends. We reviewed the literature for original research utilising the terms 'decision-to-delivery', 'decision-to-incision' or 'incision-to-delivery' and examined definitions used for decision, delivery, incision, as well as any additional time intervals that were assessed. Our analysis demonstrated an inconsistent non-standardised approach to defining these intervals, which might have clinical practice and medicolegal ramifications. We propose that the decision-to-delivery interval should be defined as follows: the interval between the time at which the senior obstetrician makes the decision that a caesarean section is required and the time at which the fetus (or first fetus in the case of multiples) is delivered. The decision time should ideally be recorded contemporaneously in the medical notes or partogram.

TBCRC 030: a phase II study of preoperative cisplatin versus paclitaxel in triple-negative breast cancer: evaluating the homologous recombination deficiency (HRD) biomarker

BACKGROUND

Cisplatin and paclitaxel are active in triple-negative breast cancer (TNBC). Despite different mechanisms of action, effective predictive biomarkers to preferentially inform drug selection have not been identified. The homologous recombination deficiency (HRD) assay (Myriad Genetics, Inc.) detects impaired double-strand DNA break repair and may identify patients with BRCA1/2-proficient tumors that are sensitive to DNA-targeting therapy. The primary objective of TBCRC 030 was to detect an association of HRD with pathologic response [residual cancer burden (RCB)-0/1] to single-agent cisplatin or paclitaxel.

PATIENTS AND METHODS

This prospective phase II study enrolled patients with germline BRCA1/2 wild-type/unknown stage I-III TNBC in a 12-week randomized study of preoperative cisplatin or paclitaxel. The HRD assay was carried out on baseline tissue; positive HRD was defined as a score ≥33. Crossover to an alternative chemotherapy was offered if there was inadequate response.

RESULTS

One hundred and thirty-nine patients were evaluable for response, including 88 (63.3%) who had surgery at 12 weeks and 51 (36.7%) who crossed over to an alternative provider-selected preoperative chemotherapy regimen due to inadequate clinical response. HRD results were available for 104 tumors (74.8%) and 74 (71.1%) were HRD positive. The RCB-0/1 rate was 26.4% with cisplatin and 22.3% with paclitaxel. No significant association was observed between HRD score and RCB response to either cisplatin [odds ratio (OR) for RCB-0/1 if HRD positive 2.22 (95% CI: 0.39-23.68)] or paclitaxel [OR for RCB-0/1 if HRD positive 0.90 (95% CI: 0.19-4.95)]. There was no evidence of an interaction between HRD and pathologic response to chemotherapy.

CONCLUSIONS

In this prospective preoperative trial in TNBC, HRD was not predictive of pathologic response. Tumors were similarly responsive to preoperative paclitaxel or cisplatin chemotherapy.

Overexpression of BLM promotes DNA damage and increased sensitivity to platinum salts in triple-negative breast and serous ovarian cancers

Background

Platinum-based therapy is an effective treatment for a subset of triple-negative breast cancer and ovarian cancer patients. In order to increase response rate and decrease unnecessary use, robust biomarkers that predict response to therapy are needed.

Patients and methods

We performed an integrated genomic approach combining differential analysis of gene expression and DNA copy number in sensitive compared with resistant triple-negative breast cancers in two independent neoadjuvant cisplatin-treated cohorts. Functional relevance of significant hits was investigated in vitro by overexpression, knockdown and targeted inhibitor treatment.

Results

We identified two genes, the Bloom helicase (BLM) and Fanconi anemia complementation group I (FANCI), that have both increased DNA copy number and gene expression in the platinum-sensitive cases. Increased level of expression of these two genes was also associated with platinum but not with taxane response in ovarian cancer. As a functional validation, we found that overexpression of BLM promotes DNA damage and induces sensitivity to cisplatin but has no effect on paclitaxel sensitivity.

Conclusions

A biomarker based on the expression levels of the BLM and FANCI genes is a potential predictor of platinum sensitivity in triple-negative breast cancer and ovarian cancer.

Abstract P4-01-16: Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission

Background: Detection of ptDNA in patients with HR+HER2- EBC in clinical remission may impact recommendations for type and duration of adjuvant endocrine therapy. A sensitive technique to identify tumor mutations in plasma is BEAMing digital PCR. The frequency and timing of detectable mutations in plasma of patients in clinical remission from HR+HER2- EBC are unknown.

Methods: We screened a prospective institutional repository for patients that met inclusion criteria. Eligible patients must have been enrolled to the repository between 12/1/2008 (repository start) and 12/31/2016, had HR+HER2- EBC, received follow-up at Johns Hopkins with appointment scheduled between 3/1/2017 and 12/31/2017, completed curative surgery at least 6 months prior to this appointment, been recommended or initiated adjuvant endocrine therapy, and been in clinical remission. Appropriate patients were approached for a current blood sample during their follow-up appointment in 2017. Blood was analyzed using a BEAMing digital PCR platform (Sysmex Inostics OncoBEAM™) for AKT1, PIK3CA, and ESR1 mutations.

Results: We identified 67 eligible patients and collected blood from 60. Most patients had relatively low risk disease including 40 patients (67%) with stage I disease, and only 21 patients (35%) received chemotherapy. Patients were evenly divided between receiving tamoxifen or an aromatase inhibitor, and some patients switched from one to the other. The majority of patients (68%) had surgery between 1 and 5 years prior to the current blood draw. Detailed patient characteristics are provided in Table 1.

Two out of the 60 patients had detectable ptDNA, both with stage IIA disease. One patient had a mutation in the ESR1 ligand-binding domain P535H 9 months after surgery and while taking adjuvant tamoxifen for 7 months. Sanger sequencing of primary tumor tissue did not reveal this mutation. Another patient had a mutation in PIK3CA exon 9 E542K 9.5 years after surgery and after taking adjuvant tamoxifen for at least 7 years. Amplifying this locus in DNA from primary tumor tissue was unsuccessful; further analysis using droplet digital PCR (ddPCR) is planned.

Conclusions: Detection of ptDNA was feasible in a relatively low-risk group of patients with HR+HER2- EBC in clinical remission. Sampling a larger number of patients is needed to gain more understanding of the frequency and timing of detectable ptDNA. Next steps should also focus on determining the natural history of detectable ptDNA in patients with HR+HER2 EBC in clinical remission which may impact adjuvant treatment recommendations.

Funding sources: Komen SAC110053, P30 CA06973, Breast Cancer Research Foundation

Table 1:Characteristics of included patients N (%)Total patients60Age at diagnosis, median(range)57 (30-77)Female59 (98)Caucasian54 (90)Postmenopausal at diagnosis36 (60)Tumor size <2 cm42 (70)Node negative45 (75)Invasive ductal histology44 (73)Received adjuvant chemotherapy21 (35)Type of adjuvant endocrine therapy Tamoxifen25 (42)Aromatase inhibitor26 (43)Tamoxifen and AI7 (12)None2 (3)Time after surgery 6 months to <1 year6 (10)1 year to <5 years41 (68)5 years to <10 years13 (22)

Citation Format: Shah M, Hunter N, Ensminger J, Shinn D, Cole AJ, Quinn HE, Edelstein DL, Wang C, Smith KL, Richardson AL, Cimino-Mathews A, Wolff AC, Cravero K, Park BH, Stearns V. Detection of plasma tumor DNA (ptDNA) in patients with hormone receptor-positive HER2-negative (HR+HER2-) early breast cancer (EBC) in clinical remission [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-01-16.

Abstract P6-02-03: Interpretation schema for optical coherence tomography images in breast tissue

Purpose

Optical coherence tomography (OCT) is an attractive technology for surgical imaging because it permits the real-time visualization of microscopic tissue morphology with a handheld probe without the need for exogeneous agents, tissue manipulation, ionizing radiation, or histological processing. While initial studies have shown that OCT is an effective margin-evaluation tool for breast conserving surgery (BCS), image interpretation and feature identification have not been directly studied. In this work, breast pathologies were assessed with a handheld OCT probe and the images were compared to histology.

Methods

Mastectomy and BCS specimens from 26 women were imaged with a handheld OCT probe, and histology slides from the same region were digitally photographed. OCT and histology images from the same region were paired by selecting the best structural matches. Because image characteristics in OCT are akin to those in ultrasound, descriptive OCT image feature terminology similar to that of ultrasound was developed. Each of these characteristics was used to select and describe OCT-histology image matches.

Results

In total, 2880 OCT images were acquired from 26 breast specimens, and 48 matching OCT-histology image pairs were identified. These matched image pairs illustrate tissue types including adipose tissue, dense fibrosis, fibroadipose tissue, blood vessels, regular and hyperplastic ducts and lobules, cysts, fibroadenoma, IDC, ILC, DCIS, calcifications, and biopsy cavities. Differentiation between pathologies was achieved by considering feature boundaries, interior appearance, posterior shadowing or enhancement, and overall morphologic patterns.

Conclusions

This is the first work to systematically catalog the features of breast OCT images. The results indicate that OCT can be used to identify important structures and distinguish between benign and malignant breast pathologies.

Citation Format: Yemul KS, Zysk AM, Richardson AL, Tangella KV, Jacobs LK. Interpretation schema for optical coherence tomography images in breast tissue [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-02-03.

Abstract P5-07-13: Identification of a cancer stem sell-specific function for the histone deacetylases, HDAC1 and HDAC7, in breast and ovarian cancer

This abstract was withdrawn by the authors.

Abstract P6-08-10: Mutational signatures impact the breast cancer transcriptome and distinguish mitotic from immune response pathways

A comprehensive whole genome analysis of a large breast cancer cohort of 560 cases (Nik-Zainal et al, submitted 2015) reports novel and existing DNA substitution and rearrangement signatures next a comprehensive list of events driving the breast cancer cell to its malignant potency. In the current study, we linked the observed genetic diversity to the breast cancer transcriptome for 260 cases for which whole genome and whole transcriptome data were both available.

Cluster analysis of the global gene expression showed the familiar view of a coherent basal-like and a heterogeneous luminal subgroup. New and previously reported1 subtype-specific aberrations with concordant expression changes were found in TP53, PIK3CA, PTEN, CCND1, CDH1 and GATA3, and mutations in PIK3CA, PTEN, AKT1 and AKT2 were mutually exclusive confirming they are active in the same pathway in breast cancer.

Integrating the identified DNA substitutions signatures with the transcriptome, we observed that the total number of substitutions in a cancer, irrespective of substitution type, was positively associated with cell cycle regulated gene expression and with adverse outcome.

In addition and more remarkably, we observed that the number substitution of two substitution signatures2 particularly associated with immune-response specific gene expression, with increased amount of tumor infiltrating lymphocytes and with a better outcome. These two signatures comprised 1) mutations of the APOBEC-type (predominant C>G in a TCN context), and 2) mutations which lacks specific features but which are strongly associated with genetic and epigenetic inactivating aberrations in BRCA1 and BRCA2.

Thus, while earlier reports3-5 imply that the sheer number of driver events triggers an immune-response, we refine this statement by observing that substitutions of a particular type are much very effective in doing so explaining the superior outcome of cancer having these particular types of substitutions. This result also implies that purposefully augmenting T-cell reactivity against amino-acid substitutions resulting from either of these two DNA substitution types could potentially improve immunotherapies in breast cancer.

1. Comprehensive molecular portraits of human breast tumours. Nature 490, 61-70 (2012).

2. Alexandrov, L.B., et al. Signatures of mutational processes in human cancer. Nature 500, 415-421 (2013).

3. Rizvi, N.A., et al. Cancer immunology. Mutational landscape determines sensitivity to PD-1 blockade in non-small cell lung cancer. Science 348, 124-128 (2015).

4. Schumacher, T.N. & Schreiber, R.D. Neoantigens in cancer immunotherapy. Science 348, 69-74 (2015).

5. Snyder, A., et al. Genetic basis for clinical response to CTLA-4 blockade in melanoma. N Engl J Med 371, 2189-2199 (2014).

Citation Format: Martens JWM, Smid M, Rodríguez-González G, Sieuwerts AM, Prager-Van der Smissen WJC, Van Der Vlugt - Daane M, Van Galen A, Nik-Zainal S, Staaf J, Brinkman AB, Van de Vijver MJ, Richardson AL, Berentsen K, Caldas C, Butler A, Martin S, Davies HD, Debets R, Meijer-Van Gelder ME, Van Deurzen CHM, Ramakrishna MR, Ringnér M, Viari A, Birney E, Børresen-Dale A-L, Stunnenberg HG, Stratton M, Foekens JA. Mutational signatures impact the breast cancer transcriptome and distinguish mitotic from immune response pathways. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-08-10.

The evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer: recommendations by an International TILs Working Group 2014

BACKGROUND

The morphological evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer (BC) is gaining momentum as evidence strengthens for the clinical relevance of this immunological biomarker. Accumulating evidence suggests that the extent of lymphocytic infiltration in tumor tissue can be assessed as a major parameter by evaluation of hematoxylin and eosin (H&E)-stained tumor sections. TILs have been shown to provide prognostic and potentially predictive value, particularly in triple-negative and human epidermal growth factor receptor 2-overexpressing BC.

DESIGN

A standardized methodology for evaluating TILs is now needed as a prerequisite for integrating this parameter in standard histopathological practice, in a research setting as well as in clinical trials. This article reviews current data on the clinical validity and utility of TILs in BC in an effort to foster better knowledge and insight in this rapidly evolving field, and to develop a standardized methodology for visual assessment on H&E sections, acknowledging the future potential of molecular/multiplexed approaches.

CONCLUSIONS

The methodology provided is sufficiently detailed to offer a uniformly applied, pragmatic starting point and improve consistency and reproducibility in the measurement of TILs for future studies.

The evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer: recommendations by an International TILs Working Group 2014

BACKGROUND

The morphological evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer (BC) is gaining momentum as evidence strengthens for the clinical relevance of this immunological biomarker. Accumulating evidence suggests that the extent of lymphocytic infiltration in tumor tissue can be assessed as a major parameter by evaluation of hematoxylin and eosin (H&E)-stained tumor sections. TILs have been shown to provide prognostic and potentially predictive value, particularly in triple-negative and human epidermal growth factor receptor 2-overexpressing BC.

DESIGN

A standardized methodology for evaluating TILs is now needed as a prerequisite for integrating this parameter in standard histopathological practice, in a research setting as well as in clinical trials. This article reviews current data on the clinical validity and utility of TILs in BC in an effort to foster better knowledge and insight in this rapidly evolving field, and to develop a standardized methodology for visual assessment on H&E sections, acknowledging the future potential of molecular/multiplexed approaches.

CONCLUSIONS

The methodology provided is sufficiently detailed to offer a uniformly applied, pragmatic starting point and improve consistency and reproducibility in the measurement of TILs for future studies.

Abstract P1-07-07: Inflammatory gene expression variations in the interval between core needle biopsy and excisional biopsy in early breast cancer

Introduction: Advancements in molecular biology have unveiled multiple breast cancer promoting pathways and potential therapeutic targets. Large randomized clinical trials remain the ultimate means of validating therapeutic efficacy, but they require large cohorts of patients and are lengthy and costly. An alternative approach is to conduct a window of opportunity study in which patients are exposed to a drug pre-surgically during the interval between the core needle biopsy (CNB) and the definitive surgery (excisional biopsy (EB)). These are non-therapeutic studies and the end point is not clinical or pathological response but rather evaluation of molecular changes in the tumor specimens that can predict response. However, since the end points of the non-therapeutic studies are biologic, it is critical to first define any biologic changes that occur in the absence of treatment. In this study, we compared the molecular profiles of breast cancer tumors at the time of the diagnostic biopsy versus the definitive surgery in the absence of any intervention.

Methods: The study was conducted with DFCI/HCC IRB approval and patient consent. Post-menopausal women with a breast lesion suspected to be cancerous were eligible for this study. We obtained a tissue specimen at the time of a CNB and if determined to be consistent with invasive carcinoma a second specimen was obtained at the time of the EB. We used the Nanostring Ncounter system to study the expression level of 148 transcripts. Since we expected that most of the tumors will be hormone receptor positive (HR+), the library included; genes that have been shown to be prognostic in HR+ tumors (Oncotype DX®, PAM50), estrogen receptor (ER) modulators, ER responsive genes and inflammatory genes. The Wilcoxon's signed rank test was used to evaluate for changes in gene expression levels between the paired samples.

Results: 25 patients were enrolled in this study and paired tumor tissue samples were obtained from all patients. 21 of the paired samples were successfully analyzed by the nanostring system. 86% of the patients are HR+/Her2−. We found that the gene expression levels of 14 out of the 148 genes (9%) did change between the CNB and EB without any intervention (p < 0.05). 8 of these 14 genes can be classified as inflammatory genes that also have known functions in tumor progression. The expression of these 8 genes was upregulated between the biopsies and include; CD68, ADM, CD14, IL6, VEGFA, CD52, CD44 and SNAI1. These changes may be due to an inflammatory response to the CNB. Ki67 expression did not change significantly between biopsies.

Conclusions: In this study we found significant gene expression variations between CNBs and EBs in 9% of the genes tested, without any therapeutic intervention. Our findings suggest that when conducting a “Window of Opportunity” clinical study to evaluate for biomarkers of response or resistance, changes in expression of inflammatory genes cannot be attributed to treatment and a control arm should be considered.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-07-07.

P1-09-03: Prevalence of Germline TP53 Mutations in Young Women with HER2−Positive Breast Cancer

Background: Li Fraumeni syndrome is a rare inherited cancer susceptibility condition associated with germline mutations in the TP53 gene, in which breast cancer (BC) is the most frequent tumor. The prevalence of TP53 mutations in population-based series of very young onset BC (<30 years at diagnosis) ranges from <1% to approximately 7%1-4. Recent data show that BC in patients carrying a germline TP53 mutation are commonly HER2 amplified (63-83%)5-7. In this study, we assessed the prevalence of germline TP53 mutations in women with HER2 positive BC diagnosed age ≤ 50 years.

Material & Methods: We identified 347 women with invasive HER2 positive BC diagnosed at age ≤ 50 years using the Clinical Operations and Research Information System (CORIS) at the Dana Farber Cancer Institute. Information on age at diagnosis, histology, hormone receptor and HER2 status as well as personal and family cancer history was confirmed from medical records. 129 patients were excluded for various reasons, including a cancer diagnosis prior to the BC and a documented BRCA1/2 mutation. A combination of Exon Grouping Analysis (EGAN) and Sanger sequencing for detection of TP53 mutations in exons 2–11 including surrounding intronic sequence was performed on 218 germline DNA samples. Multiplex Ligation-dependent Probe Amplification (MLPA) analysis for the detection of TP53 deletions or duplications is ongoing.

Results: A germline TP53 mutation was identified in 4 women diagnosed at age ≤ 50 years (1.8%, 95%CI 0.5−4.6). At BC diagnosis, they were 23, 32, 44 and 50 years. Two BC were ER+/PR+, HER2+ and 2 were ER-/PR-, HER2+. Estimate of prevalence of germline TP53 mutations by age at BC diagnosis are: age ≤ 35, 2/41 (4.9%, 95%CI 0.6−16.6), and age ≤ 45 3/168 (1.8%, 95%CI 0.4−5.1). Among the women with germline TP53 mutations, 2 met the Chompret criteria8 and none the classic LFS criteria.

Discussion: TP53 mutations were identified in a cohort of women with HER2+ BC at young age. As expected, the frequency is higher in younger women, but mutations were seen in all age groups that were evaluated. None of these women met classic LFS criteria by family history. Consideration of TP53 testing should be given to women diagnosed below age 35 who are negative for BRCA1/2 mutations regardless of family history. Analysis of other series will be helpful in reaching more stable estimates of the prevalence of mutation carriers among patients with HER2+ BC at young age.

1. Sidransky D et al. Cancer Res. 1992; 52:2984–2986.

2. Borresen AL et al. Cancer Res.1992; 52:3234–3236.

3. Lalloo F et al. Lancet 2003; 361:1101–02

4. Gonzalez KD et al. J Clin Oncol 2009;27(8):1250–6

5. Wilson JR et al. J Med Genet 2010;47(11):771–774.

6. Melhem-Bertrandt A et al: San Antonio Breast Cancer Symposium 2010: P3-12-01.

7. Masciari S et al: J Clin Oncol 29: 2011 (suppl; abstr 1519)

8. Tinat J et al. J Clin Oncol. 2009;27(26):e108–9

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-09-03.

Personalizing treatment in early-stage breast cancer: The role of standard clinical factors and genomic information in adjuvant chemotherapy decision making

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Background: The Oncotype DX recurrence score (RS) independently predicts the likelihood of benefit from adjuvant chemotherapy. However, the clinical factors that influence chemotherapy recommendations in addition to RS are not well characterized. We sought to determine how clinicians integrate the RS and standard clinicopathologic data when choosing adjuvant chemotherapy. Methods: We identified women with ER+, HER2-, LN- breast cancer seen at DFCI in whom RS testing was performed between November 2004 and October 2008. Clinical and pathological characteristics, RS and chemotherapy treatment were identified from electronic medical records. A multivariable model was used to examine which factors drove the decision to administer chemotherapy. Results: RS was performed on 269 women with the following case distribution: RS low (<18) 50%, RS intermediate (18–30) 41%, RS high (>30) 9%. Chemotherapy was given to 7% of women with low RS, compared to 42% and 86% of women with intermediate and high RS, respectively. Tumor grade, T stage, progesterone receptor expression and RS were associated with receipt of chemotherapy in univariate analyses but age, LVI and menopausal status were not. In a multivariable logistic regression model, tumor grade, size, and RS were independent predictors of chemotherapy administration. Conclusions: Oncotype DX RS plays a critical role in medical decision making for women with early stage breast cancer at this single academic institution. However, other tumor and clinical features independently contribute to chemotherapy decisions, suggesting that tailored treatment does, and should, integrate both traditional and molecular pathological factors.

[Table: see text]

No significant financial relationships to disclose.

Identification of robust, clinically relevant phenotypes of breast cancer from genome scale molecular profiling

Abstract #2036

Genome scale analysis by microarrays or array CGH holds the promise to identify novel subclasses of breast cancer or characterize functional modules of clinical relevance in a robust fashion. However, the success of these endeavors is highly dependent on several factors such as the general noise structure and noise level of high throughput measurements or the strength of association between biomarkers/gene modules and clinical outcome. We will address two issues deeply rooted in the high throughput nature of genome scale profiling, which are relevant for the accurate analysis of clinical microarray data sets: systematic bias in clinical microarray data and establishing strategies that allow extracting robust, convergent information/classification from genome scale molecular profiling of breast cancer.&#x2028; As will be demonstrated, clinical microarray data are burdened with a high level of systematic bias. We identified sources of technical bias affecting many genes in concert, thus causing spurious correlations in clinical data sets and false associations between genes and clinical variables. A method will be presented to correct for technical bias in clinical microarray data, which increased concordance with known biological relationships in multiple data sets.&#x2028; Gene expression profiling based classification of breast cancer and prognostic or clinical response associated gene expression signatures are usually derived from a single data set. However, any result extracted from a single data set will reflect to a large extent the technical (which genes are measured reliably on the microarray) and biological (such as cohort selection) bias of the given cohort. An alternative approach uses multiple, in this case 5 different, analogous clinical data sets and determines the robust, convergent information emerging from the cross data-set analysis. We will present such a method, which will reduce the impact of data set specific bias and outline robust functional modules in breast cancer, ultimately leading to the reevaluation of gene expression profiling based subtyping and diagnostic gene expression signatures in breast cancer.&#x2028; Finally, we will present evidence for the existence of at least two fundamentally different types of genome instability in breast cancer with direct implications for response to chemotherapy.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2036.

Abnormalities of the inactive X chromosome are a common feature of BRCA1 mutant and sporadic basal-like breast cancer

As a clinical entity, breast cancer appears to be a series of subforms, each with a relatively specific molecular phenotype. Among the characteristics that differentiate these subforms are sex hormone receptor expression, HER2 expression, p53 mutation, high-grade histopathology, and particular gene expression array patterns. Sporadic basal-like breast cancer is one such form. It is a relatively common, high-grade, hormone receptor and HER2-expression-negative, p53 mutation-bearing tumor and is particularly lethal. Although wild type for BRCA1, it is a sporadic phenocopy of most cases of BRCA1(/) breast cancer. Not only do the cells of the two tumors resemble one another with respect to the above-noted characteristics, they also share a defect in the maintenance of an intact, inactive X chromosome (Xi). Other high-grade and most low-grade tumors are rarely defective at Xi. This evidence suggests that an Xi defect contributes to the evolution of both sporadic and BRCA1(/) basal-like breast tumors.

Genetic analysis of lithium-associated parathyroid tumors

OBJECTIVE

The aim of this study was to determine the primary genetic events that may underlie the formation of parathyroid tumors in patients with lithium-associated hyperparathyroidism (HPT).

METHODS

Comparative genomic hybridization (CGH), loss of heterozygosity (LOH) and multiple endocrine neoplasia type 1 gene (MEN1) mutation analysis were used to analyze twelve parathyroid tumors from nine patients with lithium-associated HPT. For comparison, CGH was also carried out in a non-lithium-associated group of thirteen sporadic parathyroid tumors.

RESULTS

A higher prevalence of multiglandular disease in the lithium-associated HPT patients compared with the idiopathic sporadic patients was observed (Fisher's exact test, P=0.02). CGH alterations were detected in four lithium-associated parathyroid tumors, involving loss at 1p, 11, 15q, 22q and gain of the X chromosome. In addition, one of these four cases exhibited LOH at 11q13 and was found to contain a novel somatic MEN1 mutation (c.1193insTAC). Although fewer lithium-associated parathyroid tumors were shown to contain genetic alterations compared with the sporadic parathyroid tumors, the changes detected were those frequently associated with both familial and sporadic parathyroid tumorigenesis.

CONCLUSION

This is, to our knowledge, the first genetic analysis of parathyroid tumors in lithium-associated HPT patients. Our data indicated that the majority of lithium-associated parathyroid tumors do not contain gross chromosomal alterations and suggest that in most cases the tumorigenic pathway is independent of MEN1 and genes at 1p34.3-pter and 1q21-q32. It is possible that other discrete genetic alterations or epigenetic changes, not screened for in this study, could also be responsible for parathyroid tumorigenesis in lithium-associated HPT.

Rapid mutation scanning of genes associated with familial cancer syndromes using denaturing high-performance liquid chromatography

Germline mutations in tumor suppressor genes, or less frequently oncogenes, have been identified in up to 19 familial cancer syndromes including Li-Fraumeni syndrome, familial paraganglioma, familial adenomatous polyposis coli and breast and ovarian cancers. Multiple genes have been associated with some syndromes as approximately 26 genes have been linked to the development of these familial cancers. With this increased knowledge of the molecular determinants of familial cancer comes an equal expectation for efficient genetic screening programs. We have trialled denaturing high-performance liquid chromatography (dHPLC) as a tool for rapid germline mutation scanning of genes implicated in three familial cancer syndromes -- Cowden syndrome (PTEN mutation), multiple endocrine neoplasia type 2 (RET mutation) and von Hippel-Lindau disease (VHL mutation). Thirty-two mutations, including 21 in PTEN, 9 in RET plus a polymorphism, and 2 in VHL, were analyzed using the WAVE DNA fragment analysis system with 100% detection efficiency. In the case of the tumor suppressor gene PTEN, mutations were scattered along most of the gene. However, mutations in the RET proto-oncogene associated with multiple endocrine neoplasia type 2 were limited to specific clusters or "hot spots." The use of GC-clamped primers to scan for mutations scattered along PTEN exons was shown to greatly enhance the sensitivity of detection of mutant hetero- and homoduplex peaks at a single denaturation temperature compared to fragments generated using non--GC-clamped primers. Thus, when scanning tumor suppressor genes for germline mutation using dHPLC, the incorporation of appropriate GC-clamped primers will likely increase the efficiency of mutation detection.

Male breast cancer in Cowden syndrome patients with germline PTEN mutations

Cowden syndrome (CS) (OMIM 158350) is a multiple hamartoma syndrome associated with germline mutations in the PTEN tumour suppressor gene. While CS is characterised most commonly by non-cancerous lesions (mucocutaneous trichilemmomas, acral and palmoplantar keratoses, and papillomatous papules), it is also associated with an increased susceptibility to breast cancer (in females) and thyroid cancer, as well as non-cancerous conditions of the breast and thyroid. Here we report two cases of male breast cancer occurring in patients with classical CS phenotypes and germline PTEN mutations. The first subject was diagnosed with CS indicated primarily by mucocutaneous papillomatosis, facial trichilemmomas, and macrocephaly with frontal bossing at the age of 31 years. He developed breast cancer at 41 years and subsequently died of the disease. A PTEN mutation, c.802delG, was identified in this subject, yet none of his family members showed evidence of a CS phenotype, suggesting that this PTEN mutation may be a de novo occurrence. The second subject had a CS phenotype including multiple trichilemmomas and thyroid adenoma, developed male breast cancer at 43 years, and died of the disease at 57 years. He was a carrier of a PTEN mutation c.347-351delACAAT that cosegregated with the CS phenotype in affected family members. These two cases of male breast cancer associated with germline PTEN mutations and the CS phenotype suggest that CS may be associated with an increased risk of early onset male as well as female breast cancer.

Sporadic and familial pheochromocytomas are associated with loss of at least two discrete intervals on chromosome 1p

Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial form of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma. In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of approximately 70 cM (1pter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%) sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients. Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PC1 (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome 1p may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is likely to have a broader role in the development of endocrine malignancies.

Loss of heterozygosity in sporadic parathyroid tumours: involvement of chromosome 1 and the MEN1 gene locus in 11q13

OBJECTIVE

Hyperparathyroidism (HPT) is a common endocrine disorder. Several loci of genetic interest have been identified in parathyroid tumours, including the MEN1 gene locus at 11q13; the HPT-JT region at 1q21-q32; and a putative tumour suppressor gene on 1p. We analysed these intervals, which harbour known genes or putative loci associated with familial hyperparathyroidism, in order to clarify the involvement of the respective regions in parathyroid tumourigenesis.

DESIGN

We performed loss of heterozygosity (LOH) studies on 33 sporadic parathyroid tumours using a PCR based technique. A total of 22 microsatellite markers were used to analyse loci at 11q13, 1q21-q32 and 1p. Ten markers located distal on 1p, eight markers encompassed the HPT-JT region at 1q21-q32 and four markers surrounded the MEN1 gene locus at 11q13. MEN1 mutations were screened for using Single Strand Conformation Polymorphism analysis (SSCP) and automated sequencing of SSCP variants.

PATIENTS

Thirty-three parathyroid glands and the corresponding blood samples were obtained from 33 patients (26 females and seven males) who underwent parathyroidectomy for primary hyperparathyroidism.

RESULTS

Loss of heterozygosity was detected in 13 of 33 (39%) cases at 11q13, 6 of 33 (18%) cases at 1p, and in three of 33 (9%) cases at 1q (in conjunction with 1p loss). Only one of the 18 tumours in which LOH was detected, showed LOH at both chromosome 1 and chromosome 11. Additionally, those tumours found to exhibit LOH at 11q13 were screened for MEN1 mutations using single strand conformation polymorphism analysis (SSCP) and automated sequencing. Nine novel somatic mutations were found on the remaining allele in 13 (69%) tumours.

CONCLUSIONS

This study consolidates the role of multiple loci in the pathogenesis of sporadic parathyroid tumours. The results indicate that there are at least two genetic loci involved in sporadic parathyroid tumourigenesis on chromosome 1, one of which has been linked to the distinct familial parathyroid condition, hyperparathyroidism-jaw tumour (HPT-JT) syndrome. The high frequency of loss of heterozygosity at 1p suggests the presence of a tumour suppressor at this locus.

Mutation spectrum and genotype-phenotype analyses in Cowden disease and Bannayan-Zonana syndrome, two hamartoma syndromes with germline PTEN mutation

The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403 amino acid dual specificity phosphatase (protein tyrosine phosphatase; PTPase), was shown recently to play a broad role in human malignancy. Somatic PTEN deletions and mutations were observed in sporadic breast, brain, prostate and kidney cancer cell lines and in several primary tumours such as endometrial carcinomas, malignant melanoma and thyroid tumours. In addition, PTEN was identified as the susceptibility gene for two hamartoma syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD families and seven BZS families was screened for germline PTEN mutations. PTEN mutations were identified in 30 of 37 (81%) CD families, including missense and nonsense point mutations, deletions, insertions, a deletion/insertion and splice site mutations. These mutations were scattered over the entire length of PTEN , with the exception of the first, fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD mutations identified in this exon. Seven of 30 (23%) were within the core motif, the majority (five of seven) of which were missense mutations, possibly pointing to the functional significance of this region. Germline PTEN mutations were identified in four of seven (57%) BZS families studied. Interestingly, none of these mutations was observed in the PTPase core motif. It is also worthy of note that a single nonsense point mutation, R233X, was observed in the germline DNA from two unrelated CD families and one BZS family. Genotype-phenotype studies were not performed on this small group of BZS families. However, genotype-phenotype analysis inthe group of CD families revealed two possible associations worthy of follow-up in independent analyses. The first was an association noted in the group of CD families with breast disease. A correlation was observed between the presence/absence of a PTEN mutation and the type of breast involvement (unaffected versus benign versus malignant). Specifically and more directly, an association was also observed between the presence of a PTEN mutation and malignant breast disease. Secondly, there appeared to be an interdependent association between mutations upstream and within the PTPase core motif, the core motif containing the majority of missense mutations, and the involvement of all major organ systems (central nervous system, thyroid, breast, skin and gastrointestinal tract). However, these observations would need to be confirmed by studying a larger number of CD families.

Allelic imbalance, including deletion of PTEN/MMACI, at the Cowden disease locus on 10q22-23, in hamartomas from patients with Cowden syndrome and germline PTEN mutation

Cowden disease (CD) is a rare, autosomal dominant inherited cancer syndrome characterized by multiple benign and malignant lesions in a wide spectrum of tissues. While individuals with CD have an increased risk of breast and thyroid neoplasms, the primary features of CD are hamartomas. The gene for CD has been mapped by linkage analysis to a 6 cM region on the long arm of chromosome 10 at 10q22-23. Loss of heterozygosity (LOH) studies of sporadic follicular thyroid adenomas and carcinomas, both component tumors of CD, have suggested that the putative susceptibility gene for CD is a tumor suppressor gene. Somatic missense and nonsense mutations have recently been identified in breast, prostate, and brain tumor cell lines in a gene encoding a dual specificity phosphatase, PTEN/MMACI, mapped at 10q23.3. Furthermore, germline PTEN/MMACI mutations are associated with CD. In the present study, 20 hamartomas from 11 individuals belonging to ten unrelated families with CD have been examined for LOH of markers flanking and within PTEN/MMACI. Eight of these ten families have germline PTEN/MMACI mutations. LOH involving microsatellite markers within the CD interval, and including PTEN/MMACI, was identified in two fibroadenomas of the breast, a thyroid adenoma, and a pulmonary hamartoma belonging to 3 to 11 (27%) of these patients. The wild-type allele was lost in these hamartomas. Semi-quantitative PCR performed on RNA from hamartomas from three different tissues from a CD patient suggested substantial reduction of PTEN/MMACI RNA levels in all of these tissues. The LOH identified in samples from individuals with CD and the suggestion of allelic loss and reduced transcription in hamartomas from a CD patient provide evidence that PTEN/MMACI functions as a tumor suppressor in CD.

Genetic testing for familial cancer. Consequences of RET proto-oncogene mutation analysis in multiple endocrine neoplasia, type 2

OBJECTIVE

To assess clinician use and acceptance of RET proto-oncogene mutation testing in multiple endocrine neoplasia, type 2 (MEN 2) family members.

DESIGN

A retrospective survey of clinicians managing 26 MEN 2 families with documented RET mutations to assess the effect of genetic screening on subsequent investigation and management of family members.

SETTING

Tertiary referral center for RET mutation testing.

MAIN OUTCOME MEASURES

The screening procedures used by clinicians and the altered incidence of C-cell hyperplasia vs medullary thyroid carcinoma in genetically as opposed to biochemically identified affected family members.

RESULTS

Among RET mutation-positive patients, thyroidectomy performed for clinical or biochemical indication disclosed medullary thyroid carcinoma in 44 (98%) of 45 patients and precursor C-cell hyperplasia in only 1 (2%) patient. When prophylactic thyroidectomy was performed based on a positive genetic result, medullary thyroid carcinoma occurred in 3 (43%) of 7 patients and C-cell hyperplasia in 4 (57%) of 7 patients (P < .001). RET mutation-negative patients were not subjected to further biochemical testing, but 4 had already undergone thyroidectomy based on abnormal results of pentagastrin stimulation tests, including 2 patients who were known to be RET mutation-negative at the time of surgery. RET mutation testing was well accepted and resulted in additional family members consenting to screening in more than 85% of families.

CONCLUSIONS

Genetic screening for RET proto-oncogene mutations in MEN 2 is a powerful diagnostic tool that enables prophylactic thyroidectomy to be performed in RET mutation-positive patients at an earlier stage of the disease process than does traditional biochemical screening.

Structural organization of the human gene (PKR) encoding an interferon-inducible RNA-dependent protein kinase (PKR) and differences from its mouse homolog

The gene encoding the interferon-inducible, RNA-dependent protein kinase (PKR) was isolated as lambda phage and P1 phage clones from human genomic DNA libraries and characterized by Southern blot and nucleotide sequence analyses. Southern blot analyses were consistent with a single PKR gene, and genomic clones colocalized by fluorescence in situ hybridization to human chromosome 2p. Sequence analysis demonstrated that the human PKR gene consists of 17 exons and spans about 50 kb. The AUG translation initiation site for the 551-amino-acid PKR protein was located in exon 3; exon 17 was the largest exon and included the UAG translation termination site, AUUAAA polyadenylation signal, and putative C(A) 3' cleavage site. Two RNA-binding motifs, RI and RII, were present in exons 4 and 6, respectively, and the codon phasing of these exon junctions was conserved between them. The organization of the regulatory and catalytic subdomains of the PKR protein was remarkably preserved between the human and the mouse PKR genes; the amino acid junction positions for 13 of the 15 protein coding exons were exactly conserved.

Germline and somatic mutations in an oncogene: RET mutations in inherited medullary thyroid carcinoma

Inherited cancer syndromes predispose an individual to development of specific tumors. Somatic and germline mutations in the same tumor suppressor gene, as described in Knudson's two-mutation model, are well recognized. Inherited mutations in the RET proto-oncogene, which encodes a receptor tyrosine kinase, predispose individuals to the multiple endocrine neoplasia type 2 (MEN 2) cancer syndromes. The major component tumor of these syndromes is medullary thyroid carcinoma (MTC). To date, somatic mutations in RET have not been identified in tumors from individuals with MEN 2, although they have been well documented in sporadic MEN 2-related tumors. We have identified, among 16 MEN 2 cases with well-defined RET germline mutations, a somatic missense mutation at codon 918 of RET in 3 of 15 MTCs and in a sample with hyperplastic C-cells (presumed precursor to hereditary MTC). We suggest that the presence of a somatic mutation, in addition to the preexisting germline mutation in hereditary MTCs, may contribute to tumorigenesis in vivo.

Somatic mutations in the RET proto-oncogene in sporadic medullary thyroid carcinoma

OBJECTIVE

We have determined the frequency of specific mutations in the RET proto-oncogene in sporadic medullary thyroid carcinomas (MTCs) and correlated the presence or absence of a codon 918 mutation with the clinical characteristics of these tumours.

DESIGN

Thirty paraffin-embedded sporadic MTCs and two frozen MTCs were collected for analysis of specific mutations in the RET proto-oncogene in codons 609, 611, 618 and 620 (exon 10); 630 and 634 (exon 11); 768 (exon 13); 883 (exon 15) and 918 (exon 16). A novel primer was designed which introduced a restriction site for Rsal in the presence of the specific codon 918 mutation (ATG-->ACG) in these tumour samples. A 'clinical-genetic' correlation was performed comparing the presence of absence of the codon 918 mutation with the following clinical characteristics: age at diagnosis, tumour size, presence or absence of metastases, MTC related morbidity, and base line calcitonin levels at diagnosis or most recent follow-up.

PATIENTS

Patients were classified as having sporadic MTC if there was no family history of C-cell hyperplasia, MTC, phaeochromocytoma or parathyroid disease. Retrospective review of patient records enabled complete clinical data to be obtained in 28 of 32 patients.

MEASUREMENTS

Base line calcitonin levels were measured by radioimmunoassay or calcitonin enzyme linked immunoassay. Cysteine codons in exons 10 and 11, specifically codons 609, 611, 618, 620, 630 and 634, were screened for the presence of mutations by sequence analysis. Specific mutations occurring at codons 768, 883 and 918 were screened for by restriction endonuclease digestion of PCR products.

RESULTS

The mutation at codon 918ATG-->ACG was found in 21 of 32 (66%) MTCs and the mutation at codon 883GCT-->TTT was found in one of 32 MTCs. Where possible, the presence of 'germline-type' mutations in codons 609, 611, 618, 620, 630 and 634 were excluded. Ten MTCs did not have a mutation in codons 768, 883 or 918 of the RET proto-oncogene. The presence or absence of the somatic mutation at codon 918 did not correlate with any of the above clinical characteristics.

CONCLUSION

Somatic mutations in the RET protooncogene occur frequently in sporadic MTCs.

A rapid screening method for the detection of mutations in the RET proto-oncogene in multiple endocrine neoplasia type 2A and familial medullary thyroid carcinoma families

Multiple endocrine neoplasia type 2A (MEN2A) and familial medullary thyroid carcinoma (FMTC) are autosomal dominant inherited cancer syndromes with incomplete penetrance. Following the identification of mutations in the RET proto-oncogene that segregate with the disease phenotype in MEN2A, MEN2B, and FMTC, genetic screening of individuals with mutations in RET may be performed. We have employed restriction endonuclease digestion of polymerase chain reaction products as an alternative to sequence analysis for rapid identification of mutant gene carriers in families in which MEN2A and FMTC are segregating. Twenty-one Australasian MEN2A and FMTC families have been screened for mutations in a cysteine-rich region of the RET proto-oncogene. Seven independent mutations were identified in key individuals in 16 of these families. We have identified a mutation in codon 620, 2053 T-->C (Cys620Arg), and two mutations in codon 634 of exon 11 of RET, 2095 T-->C (Cys634Arg) and 2096 G-->A (Cys634Tyr), all three of which were present in both MEN2A and FMTC families.

Molecular cloning and characterization of the t(2;14) translocation associated with childhood chronic lymphocytic leukemia

Two rare cases of chronic lymphocytic leukemia (CLL) in children, patients AS and LH, have been found to be associated with a unique chromosomal translocation, t(2;14)(p13;q32). Previous studies have shown the breakpoints of this translocation to be in the gamma 2 switch region of the Ig heavy-chain locus on chromosome 14 and in an uncharacterized region of chromosome 2. We have cloned and characterized the translocation breakpoints to examine the possibility that an oncogene contributed to the pathogenesis of these cases of CLL. Sequence analysis of AS and LH breakpoints established that the chromosome 2 breakage in the two patients occurred only 38 bp apart and within a strong non-methylated CpG island. Furthermore, human probes from the region cross-hybridized to other species, indicating strong evolutionary conservation. Northern analysis using the chromosome 2 probes detected a 2.85-kb transcript in the tumor cells and in a CD5+ B-cell line. These data suggest that a potential oncogene located near the 2p13 breakpoint may have been activated by the t(2;14) translocation in these two cases of chronic lymphocytic leukemia.

Altered hepatic clearance and killing of Candida albicans in the isolated perfused mouse liver model

The adherence of Candida albicans was studied in situ by using the perfused mouse liver model. After exhaustive washing, 10(6) C. albicans were infused into mouse livers. At the time of recovery, 62 +/- 5% (mean +/- standard error of the mean) of the infused C. albicans were recovered from the liver and 14 +/- 3% were recovered from the effluent for a total recovery of 76 +/- 4%. This indicates that 86 +/- 3% of the original inoculum was trapped by the liver and that 24 +/- 4% was killed within the liver. Chemical pretreatment of C. albicans with 8 M urea, 12 mM dithiothreitol, 2% beta-mercaptoethanol, 1% sodium dodecyl sulfate, 10% Triton X-100, or 3 M potassium chloride or enzyme pretreatment with alpha-mannosidase, alpha-chymotrypsin, subtilisin, beta-N-acetyl-glucosaminidase, pronase, trypsin, papain, or lipase did not alter adherence of C. albicans to hepatic tissue. By contrast, pepsin pretreatment significantly decreased hepatic trapping. Simultaneous perfusion with either 100 mg of C. albicans glycoprotein per liter or 100 mg of C. albicans mannan per liter also decreased trapping. Furthermore, both substances eluted previously trapped C. albicans from hepatic tissue. Chemical pretreatment with 8 M urea, 12 mM dithiothreitol, or 3 M KCI or enzymatic pretreatment with alpha-mannosidase, subtilisin, alpha-chymotrypsin, or papain increased killing of C. albicans three- to fivefold within hepatic tissue. The data suggest that mannose-containing structures on the surface of C. albicans, for example. mannans or glucomannoproteins, mediate adherence of C. albicans within the liver. Indirectly, chemical and enzymatic pretreatment renders C. albicans more susceptible to hepatic killing.

Affecting legislation on the state level--the experiences of MMGMA and MAC

Since many political battles over healthcare legislation occur at the state level, it is vital that medical groups become involved with key groups and legislators in their states. The experiences of Minnesota and California managers in rallying behind healthcare legislation is offered as an example to other states, as well as a history of MGMA's involvement with national healthcare issues.

An Indonesian experience

Having proven that one person can make a difference, a retired administrator writes about his volunteer efforts to start a medical group practice in Indonesia.

Subcellular pathology of rat liver in cholestasis and choleresis induced by bile salts. 1. Effects of lithocholic, 3beta-hydroxy-5-cholenoic, cholic, and dehydrocholic acids

Cholestasis or choleresis was induced in the rat by intravenous infusion (0.05 to 0.2 mumole per minute per 100 grams of body weight) of sodium taurolithocholate, 3beta-hydroxy-5-cholenoate, taurocholate, and dehydrocholate either singly or in combination after or without cannulation of the common bile duct. Bile flow was monitored and ultrastructural changes were examined by scanning and transmission electron microscopy up to 3 hours after bile salt administration. Taurolithocholate induced acute cholestasis and ultrastructural alterations consisting primarily of dilation of bile canaliculi, loss of canalicular microvilli, and lamellar transformation of the canalicular membrane. Occasionally, crystalline precipitates were present within the canalicular lumen and in the pericanalicular region of hepatocytes. 3beta-Hydroxy-5-cholenoate caused similar but less severe ultrastructural changes than those induced by taurolithocholate. Dehydrocholate had a greater choleretic effect than taurocholate, but neither induced noteworthy ultrastructural change. When infused simultaneously with taurolithocholate, taurocholate reversed cholestasis and largely prevented development of the ultrastructural changes induced by taurolithocholate. In contrast, simultaneous infusion of dehydrocholate prevented neither cholestasis nor development of the ultrastructural changes induced by taurolithocholate, which were more striking than those caused by taurolithocholate or 3beta-hydroxy-5-cholenoate alone. In addition, structural changes associated with cholestasis induced by these bile salts either singly or in combination were more pronounced and frequent in the periportal zone than elsewhere in the hepatic lobule. These results suggest that both taurolithocholate and 3beta-hydroxy-5-cholenoate induce cholestasis by affecting the structural and functional integrity of the bile canalicular membrane and also, in part, by forming untransportable precipitates. The contrasting effects of taurocholate and dehydrocholate on taurolithocholate-induced changes suggest that taurocholate overcomes the effect of taurolithocholate by solubilizing it into mixed micelles, but dehydrocholate and its metabolites have little or no such effect. The intralobular variation in severity of ultrastructural changes probably reflects the accumulation of bile salts in greater concentrations in hepatocytes near the portal triads.

Acute cholestasis induced by lithocholic acid in the rat. A freeze-fracture replica and thin section study

Sodium lithocholate (LCA) was continuously infused intravenously (0.1 or 0.2 mumole per minute per 100 gm. body weight) in Wistar rats with a bile fistula for up to 4 hours. The higher dose induced complete cholestasis within 2 to 3 hours, whereas the low dose reduced the biliary output to less than 10 per cent of the preinfusion level by the 3rd hour. Ultrastructural changes which were primarily localized to the bile canaliculi and the pericanalicular region were seen 30 minutes after the onset of bile acid infusion. Dilation of the bile carnaliculi, loss of canalicular microvilli, prominence of the pericanalicular ectoplasm, and a characteristic lamellar transformation of the canalicular membrane developed, which became more prominent and widespread with progression of time. A freeze-fracture replica study revealed that the canalicular microvilli became transformed through widening and flattening into multilamellar foldings. Intramembranous granules of the canalicular membrane appeared to have become redistributed, being few or absent in the "transformed" regions. In addition, a sharply angulated, crystalline material was seen in occasional bile canaliculi. This material appeared as a negative image in thin sections, indicating its solubility in organic solvents which were used for dehydration. With the lower dose of LCA, subcellular changes were similar to, but less severe and which accompany an acute cholestasis induced by LCA is attributable to the accumulation of this compound in the bile canaliculus and its vicinity. LCA presumably causes an asymmetric perturbation in the molecular organization of the canalicular membrane which results in ultrastructural alterations and failure of fluid transport. In addition, precipitates of LCA appear to form in the bile canaliculi and may contribute to cholestasis.