BRCAness Combined With a Family History of Cancer Is Associated With a Poor Prognosis for Breast Cancer Patients With a High Risk of BRCA Mutations.

BACKGROUND: The inexpensive prediction of the characteristics of BRCA-mutated breast cancer as "BRCAness" using the somatic cells of patients with breast cancer could be useful for developing a therapeutic strategy. Our objective was to correlate BRCAness with the clinicopathologic features, including a family history (FH) of cancer, in breast cancer patients with a high risk of BRCA mutations. PATIENTS AND METHODS: The present study included 124 patients, including 55 with early-onset and 77 with triple-negative breast cancer, who had undergone resection at Kyushu University Hospital from 2005 to 2014. Early-onset breast cancer is defined as an onset in patients aged ≤ 40 years. BRCAness was performed using multiple ligation-dependent probe amplification. The patients' FH of cancer was surveyed from first- to third-degree relatives. RESULTS: Of the 124 patients, the multiple ligation-dependent probe amplification assay results indicated that 59 tumors (47.6%) had BRCAness and 27 patients (21.8%) had a positive FH for cancer. The patients with BRCAness experienced significantly shorter recurrence-free survival (RFS) and overall survival (OS) compared with those without. Patients with FH had shorter RFS and OS compared to those without BRCAness. The patients were divided into those with and without BRCAness and those with and without a positive FH. The BRCAness with FH subgroup experienced significantly shorter RFS and OS. Multivariate analysis revealed that BRCAness and a positive FH were independent negative prognostic factors. CONCLUSION: Our findings suggest that BRCAness tumors with a positive FH of cancer were associated with a poor prognosis in the BRCA-mutation high-risk group. We propose that BRCAness and a positive FH will serve to predict patients' prognosis.

Information-seeking experiences and decision-making roles of Japanese women with breast cancer.

PURPOSE: To investigate the information-seeking experiences and decision-making roles of Japanese women with breast cancer, to examine the relationship between information-seeking experiences and decision-making roles, and to explore the factors that influenced taking a more active role than the preferred role during the treatment decision-making process. METHODS: In a cross-sectional study, women with breast cancer were retrospectively administered the Control Preferences Scale and the Information-Seeking Experience Scale. The Chi-Square test was used to compare differences among individual variables in decision-making roles and information-seeking experiences. Logistic regression analysis was used to explore the factors that influenced taking a more active role than the preferred role. RESULTS: One hundred and four patients with breast cancer participated in the investigation. Eighty-five patients (78%) perceived themselves as having knowledge of breast cancer and most patients (92%) sought information on breast cancer. The preferred roles in decision-making that they reported having before treatment were 18% active, 69% collaborative and 13% passive. The actual roles they perceived having experienced were 27% active, 43% collaborative and 30% passive. Although there was concordance of preferred and actual role for only 59% of the women, most patients reported that they were satisfied with their decision-making. Many women with breast cancer reported negative experiences with information seeking, including wanting more information (49%), expending a lot of effort to obtain the information needed (53%), not having enough time to obtain needed information (55%), frustration during the search for information (44%), concerns about the quality of the information (45%) and difficulty understanding the information received (49%). This study revealed that having a more active actual role than the initial preferred role was associated with emotional expression to the physician, having undergone mastectomy, and the desire for more information. CONCLUSION: Most women with breast cancer sought information on breast cancer and expressed a preference for a collaborative relationship with physicians in treatment decision-making. Patients who expressed emotion to their physician, wanted more information, and underwent mastectomy were most likely to change their actual decision-making role toward a more active choice.

Short-term and low-dose prednisolone administration reduces aromatase inhibitor-induced arthralgia in patients with breast cancer.

Aromatase inhibitors (AIs) are important therapeutic drugs for postmenopausal women with hormone receptor-positive breast cancer. However, adverse effects of AIs such as arthralgia have been extensively reported. We performed a joint prospective, multi-institutional investigation to find out whether a low-dose and short-term prednisolone is effective against AI-induced arthralgia in 27 patients with breast cancer. Patients were administered 5 mg of oral prednisolone once a day in the morning for only one week. Patients were then asked to answer a questionnaire about joint pain symptoms at one week, one month and two months after the beginning of prednisolone use. Joint pain symptoms improved in 67% of patients immediately after prednisolone use, with 63% still reporting analgesic effect at one month, and 52% at two months after beginning internal use of prednisolone. At one week, one month and two months after the use of prednisolone, 30%, 30% and 26% of patients reported improved daily life, respectively. Our results suggest that prednisolone could substitute non-steroidal anti-inflammatory drugs, acetoaminophen or cyclooxygenase-2 inhibitors in patients with AI-induced arthralgia.

The Hedgehog signaling pathway plays an essential role in maintaining the CD44+CD24-/low subpopulation and the side population of breast cancer cells.

The side population (SP) and the CD44(+)/CD24(-/low) population have been reported in separate studies to include more tumorigenic cells than other populations, and to have the ability to form new tumors and undergo heterogeneous differentiation in breast cancer tissue. However, the relationship between these two populations has not yet been explored in breast cancer cells. Here it is shown that the SP and the CD44(+)/CD24(-/low) populations are overlapping. Both populations were resistant to paclitaxel. Components of the Hedgehog (Hh) signaling pathway were more highly expressed in these cell populations at both the mRNA and protein levels compared with other populations. Furthermore, inhibition of Hh signaling activity suppressed the proliferation of both populations. The significance of Hh signaling activity in the proliferation of both populations was confirmed by the effect of an si-RNA against Gli1, a trans-activator of the Hh signaling pathway, on the proliferation of both populations. These data suggest that the Hh signaling pathway is essential for the proliferation of the tumorigenic population of breast cancer cells, and that this pathway might represent a new candidate for breast cancer therapy targeting cancer stem cells.

The Hedgehog pathway is a possible therapeutic target for patients with estrogen receptor-negative breast cancer.

Understanding the expression patterns of estrogen receptor-alpha (ERalpha) is essential for determining therapeutic strategies for patients with breast cancer. The prognosis of patients with ERalpha-negative breast cancer is still poor. We have previously shown that Hedgehog (Hh) signaling is constitutively activated in breast cancer and that Hh signaling could be a new therapeutic target. Therefore, in this study, whether or not Hh signaling could be utilized as a therapeutic target for patients with ERalpha-negative breast cancer was examined. For this purpose, three ERalpha-negative breast cancer cell lines were used in which Hh pathway-related molecules such as the ligand Patched1 and the transcriptional factor Gli1 as target cells are expressed. Cyclopamine, an inhibitor of the Hh pathway, significantly suppressed both the cell proliferation and invasion ability of these cancer cells. In addition, the knockdown of Gli1 by RNA interference in these cells also significantly reduced both cell proliferation and invasion ability. Since our previous data have shown a constitutive activation of the Hh pathway in surgically-resected ERalpha-negative breast cancer specimens, the Hh pathway, especially Gli1, may be a useful therapeutic target for patients with ERalpha-negative breast cancer.

Circumscribed mass lesions on mammography: dynamic contrast-enhanced MR imaging to differentiate malignancy and benignancy.

PURPOSE: We evaluated the magnetic resonance (MR) features of breast lesions showing circumscribed mass on mammography to understand the characteristics that differentiate malignancy and benignancy. MATERIALS AND METHODS: Our institutional review board approved the study, and informed consent was waived. Using logistic regression analysis, we examined morphologic and kinetic MR imaging data of 90 breast lesions (43 malignant, 47 benign) that showed circumscribed mass on mammography. RESULTS: Features identified as having high odds for malignancy included: rim enhancement (odds ratio, 70.894; 95% confidence interval (CI), 7.525-667.938); heterogeneous enhancement (odds ratio, 10.839; 95% CI, 1.032-113.856); and washout dynamic pattern (odds ratio, 46.262; 95% CI, 3.716-575.901). Combinations of washout dynamic pattern and either rim or heterogeneous enhancement reflected excessively high prediction probability for malignancy (>0.95), whereas combinations lacking washout dynamic pattern and with either homogeneous enhancement or dark internal septation revealed excessively low prediction probability for malignancy (<0.05). CONCLUSION: Breast cancers with circumscribed mass on mammography could be differentiated from benign masses using internal enhancement and the kinetic pattern of contrast-enhanced breast MR imaging.

Novel link between estrogen receptor alpha and hedgehog pathway in breast cancer.

Ligand-dependent constitutive activation of the hedgehog (Hh) pathway is important in the development of various carcinomas including breast cancer. A link between estrogen receptor alpha (ERalpha) and the Hh pathway in human breast cancer is shown here for the first time. In ERalpha-positive cells, estrogen depletion decreased the expression of sonic hedgehog (Shh), a ligand of the Hh pathway, while estrogen supplementation triggered Shh up-regulation. This estrogen-induced Shh expression activated the Hh pathway in a ligand-dependent manner, and increased cell proliferation. These effects were suppressed by ERalpha inhibitors, including ICI 182,780 (ICI), the dominant negative form of ERalpha and small interfering RNA (siRNA) against ERalpha. Consistent with the in vitro data, a positive correlation between ERalpha and Shh expression was found in breast cancer tissues. These data suggest that ERalpha regulates the Hh pathway through Shh induction, and promotes breast cancer development.

Phyllodes tumor of the breast: correlation between MR findings and histologic grade.

PURPOSE: To retrospectively evaluate the magnetic resonance (MR) imaging findings of phyllodes tumor of the breast and to compare these findings with the histologic grade. MATERIALS AND METHODS: Institutional review board approval and informed consent were obtained. The authors reviewed the MR findings in 30 female patients aged 16-73 years (mean, 40.2 years) with surgically confirmed phyllodes tumors. Analyzed MR findings included tumor shape, margin, internal enhancement, and size; signal intensity (SI) of tumor higher than that of normal breast tissue on T1-weighted images; SI of tumor lower than or equal to that of normal tissue on T2-weighted images; cyst wall appearance; kinetic curve assessment; and apparent diffusion coefficient (ADC). The MR findings and histologic grade were statistically analyzed to determine whether any correlations existed. Significant MR findings were compared with histopathologic findings. RESULTS: Nineteen benign, six intermediate (characterized by five to nine cell reproductions at 10 high-power fields, pushing or infiltrative margins, moderate stromal cellularity, and atypia and overgrowth), and five malignant phyllodes tumors were assessed. Irregular cyst wall (P = .003), tumor SI lower than or equal to normal tissue SI on T2-weighted images (P = .005), and low ADC (P = .001) correlated significantly with histologic grade. Tumor SI higher than normal tissue SI on T1-weighted images was more frequent in the malignant (in three of five tumors) and intermediate (in three of six tumors) groups than in the benign group (in two of 19 tumors); however, it was not a significant finding (P = .024). Tumor SI higher than normal tissue SI on T1-weighted images and irregular cyst wall corresponded histopathologically to hemorrhagic infarction and necrosis, respectively. Tumor SI lower than or equal to normal tissue SI on T2-weighted images and low ADC corresponded histopathologically to stromal hypercellularity. Other findings were not significant. CONCLUSION: Several MR findings can be used to help determine the histologic grade of phyllodes breast tumors.

MR imaging features of pure mucinous carcinoma of the breast.

OBJECTIVE: To characterize MR imaging features of pure mucinous carcinoma of the breast. MATERIALS AND METHODS: MR images obtained from 16 women (age range, 29-81; mean age, 57 years) with pure mucinous carcinoma of the breast determined at surgery were reviewed. The MR findings used were shape, margin, internal mass enhancement, kinetic curve pattern on dynamic study, signal intensity on short time inversion recovery (STIR) T2-weighted images, and non-mass-like enhancement around the main tumor. Non-mass-like enhancement was compared with the presence of extensive intraductal component (EIC) on histopathological findings. RESULTS: Eleven tumors (69%) had lobular contour, and nine tumors (56%) had smooth margin. Eight tumors (50%) showed rim enhancement and six tumors (38%) showed heterogeneous enhancement. Fourteen tumors (88%) showed a persistent enhancing pattern on kinetic curve. Fifteen tumors exhibited homogenous strongly high signal intensity on STIR T2-weighted images. In six cases with EIC, five cases had non-mass-like enhancement around the main mass. CONCLUSIONS: MR findings such as lobular shape, rim or heterogeneous enhancement, persistent pattern on kinetic curve, and homogeneous strongly high signal intensity on STIR T2-weighted images may be useful in diagnosing pure mucinous carcinoma. Moreover, linear-ductal enhancement around main mass may indicate presence of EIC.

Hepatic ischemia/reperfusion injury is prevented by a novel matrix metalloproteinase inhibitor, ONO-4817.

BACKGROUND: Matrix metalloproteinases (MMPs) play an important role in inflammation and neoplastic invasion and metastasis. Little is known about the effects of MMP inhibitors on hepatic ischemia/reperfusion injury. The aim of this study is to examine the inhibitory effects of ONO-4817 (oral inhibitor of MMPs) in rats. METHODS: Hepatic ischemia/reperfusion was induced in male Wister rats by clamping the portal vein and hepatic artery. The animals were randomized into an ONO-4817 group (300 mg/kg body weight per/day) and a vehicle group by oral gavage of a test substance. Serum alanine aminotransferase, histologic changes, gelatinolytic activity, MMP-2 and MMP-9 activities, tissue inhibitor of metalloproteinase 2 (TIMP-2) messenger RNA (mRNA) levels, and mRNA and serum levels of tumor necrosis factor alpha (TNFalpha) and interleukin 1beta (IL-1beta) were measured in both groups. RESULTS: ONO-4817 prevented ischemia/reperfusion injury to the hepatocytes as shown by significant reductions of serum alanine aminotransferase and less severe histologic changes. Gelatinolytic activity was inhibited markedly in the liver of the ONO-4817 group as demonstrated by film in situ zymography. MMP-9 and MMP-2 activities also were inhibited in the ONO-4817 group as shown by gelatin zymography. TIMP-2 mRNA levels showed no significant differences between the 2 groups. TNFalpha mRNA showed no downregulation, but IL-1beta mRNA was downregulated in the liver of the ONO-4817 group 1 to 3 hours after reperfusion. Serum levels of TNFalpha and IL-1beta showed a significant decrease in the ONO-4817 group, compared with the vehicle group after reperfusion. CONCLUSIONS: Hepatic ischemia/reperfusion injury was improved by a novel MMP inhibitor, ONO-4817, not only by inhibition of gelatinolytic activity but also by a decrease in release of inflammatory cytokines.

Inhibition of inducible nitric oxide synthase prevents hepatic, but not pulmonary, injury following ischemia-reperfusion of rat liver.

The aim of this study was to investigate the contribution of inducible nitric oxide synthase (iNOS)-derived nitric oxide on the liver and lung injury following hepatic ischemia-reperfusion (I/R) using a novel and potent iNOS inhibitor, ONO-1714. Rats were subjected to 90 min of partial hepatic ischemia followed by 3, 6, 12, and 24 hr of reperfusion. Expression of iNOS mRNA peaked at 3 hr of reperfusion in the liver and lung. Plasma nitric oxide levels were increased fourfold at 24 hr of reperfusion and plasma ALT was increased, reaching a peak at 12 hr of reperfusion; both were significantly inhibited by ONO-1714. Histological examination revealed extensive liver damage, whereas this was not seen in the ONO-1714 group. Lung injury was not significantly changed in groups with versus without ONO-1714. Nitrotyrosine expression was seen in regions similar to those of the histological injuries of the liver, while this staining was absent in the ONO-1714 group. These data show that generation of peroxynitrite could be involved in the pathogenesis of liver injury but not lung injury after hepatic I/R. Inhibition of iNOS could be applied for attenuation of liver injury following hepatic I/R.

Purification, characterization and biological significance of tumor-derived exosomes.

Exosomes are nanovesicles that are released into the extracellular environment during the fusion of multivesicular bodies with the plasma membrane. Exosomes released from dendritic cells, dexosomes, have several biological functions, for example as immunostimulants. Some tumor cells also secrete exosomes (Tu-exosomes). Although experimental data obtained with the use of dexosomes suggest a biological function of Tu-exosomes, this still remains poorly understood. To examine the function of Tu-exosomes, we established a method for collecting highly purified Tu-exosomes, using paramagnetic beads coated with antibodies against tumor-specific proteins such as HER2/neu. With these antibody-coated beads (Ab-beads), it was possible to collect HER2-expressing Tu-exosomes of high purity. Tu-exosomes were also collected from malignant ascites, which contain exosomes secreted from various types of cells such as tumor cells, lymphoid cells and mesothelial cells. The isolation of Tu-exosomes was confirmed by FACS analysis. With regard to their biological functions, Tu-exosomes cultured with a human breast cancer cell line bound to the cell surface and increased tumor cell proliferation. These data indicate that Tu-exosomes may have physiological functions.

Intraoperative parathyroid hormone assay in patients with Graves' disease for prediction of postoperative tetany.

We measured intraoperative parathyroid hormone (IOPTH) levels before and after thyroidectomy in a large group of patients to test whether changes in IOPTH can predict postoperative tetany. Subjects were 111 consecutive patients (94 females and 17 males) with Graves' disease undergoing subtotal thyroidectomy. Blood samples for IOPTH assay were obtained after anesthesia (basal) and following skin closure (postoperative). Data were compared between patients who developed tetany (n = 9) and those who did not (n = 102). There was no significant difference in sex, age, period of antithyroid drug administration, or the weight of the thyroid between the two groups. The preoperative serum calcium level was significantly lower (p < 0.05) and the basal IOPTH significantly higher (p < 0.05) in the tetany group than in the non-tetany group. The IOPTH level was significantly lower (p < 0.005) and the average percent decrease in IOPTH levels was higher (p < 0.001) in the tetany group than in the non-tetany group. A decrease in IOPTH of more than 70% was shown to be 78% sensitive, 94% specific, and 93% accurate, and it has 78% positive predictive value and 94% negative predictive value for the development of tetany. Our study shows that a postoperative decrease of IOPTH level is the most predictive of postoperative tetany of the clinical risk factors investigated. We recommend IOPTH measurement as an adjunct to postoperative management of patients with Graves' disease to assist in preventing hypocalcemia and determining the earliest time for safe discharge.

Thyroid evaluation in patients with primary hyperparathyroidism.

We evaluated the efficacy of preoperative high-resolution ultrasonography (US) for diagnosing possible concomitant thyroid disease which affects the surgical management in patients with primary hyperparathyroidism (pHPT). One hundred and nine patients with sporadic pHPT underwent US with or without ultrasound-guided fine-needle aspiration biopsy (US-FNAB). Diagnosis of concomitant thyroid nodules by US and US-FNAB were compared with the histopathological findings. Of the 109 patients, 19 (17.4%) had malignant thyroid nodules, 26 (23.9%) had benign thyroid nodules alone, and 12 (11.0%) had diffuse goiter. The sensitivity, specificity, and accuracy of diagnosing 72 thyroid nodules were 91.3%, 91.8%, and 91.7% for US, 57.9%, 94.3%, and 81.5% for US-FNAB, and 95.7%, 91.8%, and 93.1% for combined US and US-FNAB, respectively. True positive/false negative ratio of US-FNAB diagnosis was significantly lower in nodules of 5-9 mm than nodules of 10 mm or more. Four unexpected thyroid cancers existed at a different site in 3 of the 39 patients with palpable thyroid disease. Five thyroid cancers were histopathologically confirmed in 5 (7.1%) of 70 patients without palpable thyroid disease. Eight (88.9%) of the 9 non-palpable thyroid cancers were accurately diagnosed by combined US and US-FNAB. Preoperative US is useful for evaluation of possible concomitant thyroid disease, especially for prediction of malignancy.

Significant clinical differences in primary hyperparathyroidism between patients with and those without concomitant thyroid disease.

PURPOSE: We evaluated the differences in diagnosis and treatment for primary hyperparathyroidism (pHPT) in patients with and those without concomitant thyroid disease. METHODS: One hundred and ten patients with pHPT underwent parathyroid localization and thyroid examination by ultrasonography (US) and sestamibi scintigraphy (MIBI). The clinical and biochemical findings, parathyroid localization, and operations performed were compared in 49 patients without thyroid disease and 61 patients with thyroid disease. RESULTS: Asymptomatic hypercalcemia was significantly more prevalent in patients with concomitant thyroid disease (88.5%) than in those without thyroid disease (49.0%) (P < 0.01). The mean serum calcium was significantly higher and the inorganic phosphate level was significantly lower in patients without concomitant thyroid disease than in those with concomitant thyroid disease (P < 0.05, P < 0.01, respectively). The pathologic parathyroid gland was identified significantly more often in patients without concomitant thyroid disease than in those with concomitant thyroid disease both by US and MIBI (P < 0.05). Unilateral exploration was performed more often in patients without thyroid disease than in those with thyroid disease (P < 0.01). CONCLUSION: Primary hyperparathyroidism was diagnosed at an earlier stage in patients with concomitant thyroid disease. Thyroid disease concomitant with pHPT influenced parathyroid localization as well as the indication for minimally invasive parathyroidectomy.

Enhanced efficacy of conditionally replicating herpes simplex virus (G207) combined with 5-fluorouracil and surgical resection in peritoneal cancer dissemination models.

BACKGROUND: The therapeutic efficacy of G207, a replication-competent herpes simplex virus, for malignancies is increased when combined with certain chemotherapies, but the mechanism is unclear and the interaction between G207 and surgical resection has not been extensively studied. The goals of the current study were to examine the performance of combination treatments for peritoneal disseminated cancers and to explore the mechanism of effective combinations. METHODS: Hamsters and SCID and BALB/c mice harboring peritoneal dissemination of gallbladder, gastric or colon cancer cells were treated with G207, 5-fluorouracil (5FU), or surgical resection alone, or G207 combined with 5FU or surgery. Animal survival, antiviral immunity, intratumoral ribonucleotide reductase activity, and viral spread were compared between the groups. RESULTS: The combination of G207 and 5FU prolonged the survival of hamsters bearing peritoneal dissemination of gallbladder cancer compared with the controls, G207 alone and 5FU alone. 5FU did not suppress the production of neutralizing antibodies against G207, but increased ribonucleotide reductase activity and viral spread in subcutaneous gallbladder tumors. The enhanced efficacy of the combination treatment was also observed in immunodeficient mice with disseminated gastric cancer. Although surgical resection did not significantly prolong animal survival or increase the intratumoral activity of ribonucleotide reductase, long-term survivors emerged from groups of animals treated with surgical resection and G207 for gallbladder and colon disseminated cancers. CONCLUSIONS: These results indicate that the increased activity of ribonucleotide reductase in tumors mediated by 5FU and the decreased tumor burden resulting from surgical resection may enhance the therapeutic efficacy of oncolytic herpes virus for peritoneal disseminated cancer.

A case of breast cholesterol granuloma accompanied by cancer.

Cholesterol granuloma of the breast is a very rare benign disease with clinical and imaging features that are often indistinguishable from cancer preoperatively. We report a case of breast cholesterol granuloma accompanied by cancer. The patient was a 78-year-old woman who complained of a lump in her right breast. Mammography and ultrasonography showed a well-circumscribed mass. Fine needle aspiration cytology showed many cholesterol crystals and inflammatory cells without malignancy. With a diagnosis of cholesterol granuloma, tumor extirpation was performed. Histopathologic examination revealed cholesterol granuloma together with breast cancer, and additional partial mastectomy was subsequently performed. It is noted that breast cholesterol granuloma could be accompanied by cancer.

Pitavastatin, a potent hydroxymethylglutaryl coenzyme a reductase inhibitor, increases cholesterol 7 alpha-hydroxylase gene expression in HepG2 cells.

BACKGROUND: The effect of pitavastatin on the mRNA levels of apolipoprotein (apo) A-I, peroxisome proliferator-activated receptor alpha (PPARalpha), cholesterol 7alpha-hydroxylase (CYP7A1), and farnesoid X receptor (FXR) in HepG2 cells was examined to establish whether pitavastatin affects bile acid synthesis and if so, to determine a possible molecular mechanism. METHODS AND RESULTS: HepG2 cells were cultured in serum-free Dulbecco's modified Eagle medium for 18 h before drug treatment. Total RNA was extracted at set times and mRNA levels were quantified by reverse transcription-real time polymerase chain reaction. Pitavastatin at 0.1, 1, 5, and 10 micromol/L increased the mRNA levels of apo A-I, PPARalpha, CYP7A1, and FXR in a dose-dependent manner. The mRNA levels of apo A-I, PPAR alpha, CYP7A1, and FXR similarly increased with increasing doses of pitavastatin. Coincubation of mevalonate (4 mmol/L) with pitavastatin (5 micromol/L) reversed the inductive effects of pitavastatin on the mRNA levels of these genes, indicating that the inductive effects of pitavastatin were related to its inhibition of HMG-CoA reductase. CONCLUSIONS: Pitavastatin increased the mRNA levels of CYP7A1 in HepG2 cells, suggesting that increased conversion of cholesterol to bile acids may be the mechanism for its potent low-density lipoprotein cholesterol-lowering effects.

Regulation of bile acid synthesis under reconstructed enterohepatic circulation in rats.

Cholesterol 7alpha-hydroxylase (CYP7A1) is regulated by bile acids through the farnesoid X receptor (FXR) mechanism in a negative feedback fashion. However, the fact that CYP7A1 is down-regulated by intraduodenal administration of bile acid, but not by intravenous administration may not be explained only by this mechanism. The aim of this study was to establish a new rat model with reconstructed or simulated enterohepatic circulation to examine if intravenous or portal administration of bile acid can regulate CYP7A1. Under biliary drainage, taurocholate (0 or 6 micromol/h/100g body weight) was administered continuously for 48h into the duodenum (ID-0/ID-6), femoral vein (IV-0/IV-6), or portal vein (IP-0/IP-6) to create a condition in which biliary bile acids were continuously lost, and a similar dose of taurocholate was supplied to the liver simultaneously. CYP7A1 activity and mRNA expression of the ID-0 group were significantly increased compared with the no treatment (NT) group. CYP7A1 activity and mRNA expression of the ID-6 group were suppressed significantly to 41 and 46% of those of the ID-0 group, respectively. In the IV-6 and IP-6 groups, however, enzyme activity and mRNA expression were decreased slightly, but the suppression was not statistically significant. The results suggested that portal as well as intravenous administration of bile acids cannot suppress bile acid synthesis as effectively as intraduodenal administration. It was concluded that an unidentified regulatory factor other than the nuclear receptors may be involved in bile acid synthesis in vivo.