Recombinant ADAMTS13 for Hereditary Thrombotic Thrombocytopenic Purpura.

A 27-year-old patient with a history of severe obstetrical complications and arterial thrombosis received a diagnosis of hereditary thrombotic thrombocytopenic purpura (TTP) due to severe ADAMTS13 deficiency when she presented with an acute episode in the 30th week of her second pregnancy. When the acute episode of hereditary TTP became plasma-refractory and fetal death was imminent, weekly injections of recombinant ADAMTS13 at a dose of 40 U per kilogram of body weight were initiated. The patient's platelet count normalized, and the growth of the fetus stabilized. At 37 weeks 1 day of gestation, a small-for-gestational-age boy was delivered by cesarean section. At the time of this report, the patient and her son were well, and she continued to receive injections of recombinant ADAMTS13 every 2 weeks. (Funded by the Swiss National Science Foundation.).

Tubo-Ovarian Transitional Cell Carcinoma and High-grade Serous Carcinoma Show Subtly Different Immunohistochemistry Profiles.

Tubo-ovarian transitional cell carcinoma (TCC) is grouped with high-grade serous carcinoma (HGSC) in the current World Health Organization classification. TCC is associated with BRCA mutations and a better prognosis compared with HGSC. Previous papers examining the immunohistochemical features of TCC have studied limited numbers of samples. No marker reflecting the biological difference between TCC and HGSC is known. We collected a large cohort of TCC to determine whether TCC and HGSC could be distinguished by immunohistochemistry. A tissue microarray was built from 89 TCC and a control cohort of 232 conventional HGSC. Immunohistochemistry was performed, scored, and statistically analyzed for routine markers of HGSC and urothelial tumors: PAX8, WT1, p53, p16, ER, p63, and GATA3. Using scoring cutoffs commonly employed in clinical practice, the immunohistochemical profile of TCC was indistinguishable from HGSC for all markers. However, more detailed scoring criteria revealed statistically significant differences between the 2 groups of tumors with respect to ER, PAX8, and WT1. HGSC showed more diffuse and intense staining for PAX8 (P=0.004 and 0.001, respectively) and WT1 (P=0.002 and 0.002, respectively); conversely, TCC showed more intense staining for ER (P=0.007). TCC and HGSC therefore show subtle differences in their immunohistochemical profiles which might reflect underlying (epi)genetic differences. Further studies using proteomic analysis will focus on the identification of differentially expressed proteins that might serve as markers of TCC-like differentiation, which could help explain biologic differences between TCC and HGSC and might identify other cases of HGSC with a better prognosis.

Survival of breast cancer patients in rural Ethiopia.

PURPOSE: To describe the histopathological characteristics and survival of female breast cancer (BC) patients in a rural setting with limited access to adjuvant treatment. METHODS: A prospective study of 107 histologically confirmed BC patients treated with surgery from 2010 to 2016 from rural parts of western Ethiopia. Referral pathology was performed, and active follow-up was conducted. Adjusted cox regression analysis (hazard ratio [HR]) was performed. RESULTS: The median age at diagnosis was 45 (16-83) years; 57% of the patients presented with cT3/4 tumors, 71% with clinically positive lymph nodes, 21% with HER2-overexpression (Dako3+) and 68% with grade 3 tumors. Estrogen and/or progesterone receptor expressions were present in 66% and triple-negative disease in 25%. The estimated 1- and 2-year overall survival probability rates were 78 and 53%, respectively. The 2-year survival for patients with clinically positive lymph nodes was 44% compared to 73% for patients with lymph node-negative disease (HR 2.44; 95% confidence interval [95% CI] 1.19-5.02). The corresponding 2-year survival for patients with cT4 tumors was 25% versus 68% for patients with cT1-2 tumors (cT1-3 vs. cT4 HR 3.86; 95% CI 1.82-13.63). The 2-year survival for patients with hormone receptor-negative disease was 40% compared to 59% for patients with hormone receptor-positive disease (HR 1.92; 95% CI 1.06-3.47). CONCLUSION: The majority of breast cancer patients treated with surgery in rural parts of western Ethiopia are diagnosed at advanced stage and have hormone receptor-positive disease. Nearly half of the patients die within 2 years. These findings underscore the need for provision of adjuvant hormonal therapy and for the establishment of pathology service including hormone receptor testing.

Gene Expression (mRNA) Markers for Differentiating between Malignant and Benign Follicular Thyroid Tumours.

Distinguishing between follicular thyroid cancer (FTC) and follicular thyroid adenoma (FTA) constitutes a long-standing diagnostic problem resulting in equivocal histopathological diagnoses. There is therefore a need for additional molecular markers. To identify molecular differences between FTC and FTA, we analyzed the gene expression microarray data of 52 follicular neoplasms. We also performed a meta-analysis involving 14 studies employing high throughput methods (365 follicular neoplasms analyzed). Based on these two analyses, we selected 18 genes differentially expressed between FTA and FTC. We validated them by quantitative real-time polymerase chain reaction (qRT-PCR) in an independent set of 71 follicular neoplasms from formaldehyde-fixed paraffin embedded (FFPE) tissue material. We confirmed differential expression for 7 genes (CPQ, PLVAP, TFF3, ACVRL1, ZFYVE21, FAM189A2, and CLEC3B). Finally, we created a classifier that distinguished between FTC and FTA with an accuracy of 78%, sensitivity of 76%, and specificity of 80%, based on the expression of 4 genes (CPQ, PLVAP, TFF3, ACVRL1). In our study, we have demonstrated that meta-analysis is a valuable method for selecting possible molecular markers. Based on our results, we conclude that there might exist a plausible limit of gene classifier accuracy of approximately 80%, when follicular tumors are discriminated based on formalin-fixed postoperative material.

The new WHO classification of ovarian, fallopian tube, and primary peritoneal cancer and its clinical implications.

INTRODUCTION: Molecular pathological research has contributed to improving the knowledge of different subtypes of ovarian cancer. In parallel with the implementation of the new FIGO staging classification, the WHO classification was revised. The latter is mainly based on the histopathological findings and defines the actual type of tumor. It has, therefore, also an important impact on prognosis and therapy of the patient. MATERIALS AND METHODS: The new WHO Classification of Ovarian Cancer published 2014 by Robert Kurman and co-authors is summarized. The major changes compared to the hitherto existing classification are presented. RESULTS: The new classification eliminates the previous focus of mesothelial origin of ovarian cancer. Instead, it features a discussion of tubal carcinogenesis of hereditary and some other high-grade serous carcinomas. The previously assumed pathogenesis pathway may be correct for some, but not for all, serous cancers. The new classification was established to classify ovarian cancer in a more consistent way. The earlier transitional cell type of ovarian cancer has been removed while seromucinous tumors have been added as a new entity. The role of some borderline tumors as one possible step in the progression from benign to invasive lesions is incorporated. The article summarizes the essential updates concerning serous, mucinous, seromucinous, endometrioid, clear-cell, and Brenner tumors. CONCLUSION: The new WHO classification takes into account the recent findings on the origin, pathogenesis, and prognosis of different ovarian cancer subtypes. The tubal origin of hereditary and some non-hereditary high-grade serous cancers is mentioned in contrast to the hitherto theory of mesothelial origin of tumors. Seromucinous tumors represent a new entity.

The Value of Serum CA125 in the Diagnosis of Borderline Tumors of the Ovary: A Subanalysis of the Prospective Multicenter ROBOT Study.

OBJECTIVE: The value of the serum tumor marker CA125 in borderline tumors of the ovary (BOTs) is not well defined, with unclear benefit in both diagnosis and follow-up. The aim of the present project was to identify the predictive value of CA125 for stage and relapse. METHODS: CA125 data were extracted from the ROBOT multicenter study of patients with BOT treated between 1998 and 2008 in 24 German centers. While patients' data were retrieved retrospectively from hospital records and clinical tumor registries, follow-up and independent central pathology review were performed prospectively. RESULTS: We identified 127 patients from the ROBOT database fulfilling the eligibility criterion of available CA125 at initial diagnosis. Eighty-three (65.3%) patients had increased CA125 levels (>35 U/L). Of the patients, 85.0% presented with serous and 13.4% with mucinous BOT histology, whereas 29.9% had stage I disease. Fifteen (11.8%) patients experienced a relapse. Multivariate analysis identified raised CA125, young age, and serous histology as independent predictors of peritoneal implants of any type at initial presentation. Raised CA125 at initial diagnosis was, however, not an independent predictor of future relapse. DISCUSSION: Elevated CA125 seems to be associated with the presence of peritoneal implants of any type at initial diagnosis of serous BOT, but failed to have any independent predictive value on future relapse. Prospective multicenter studies are warranted to evaluate CA125 measurements in the follow-up management of BOT.

Opportunistic salpingectomies for the prevention of a high-grade serous carcinoma: a statement by the Kommission Ovar of the AGO.

The detection of premalignant cells in the epithelium of the fallopian tube has resulted in revolutionary theories regarding the origin of epithelial ovarian cancer (EOC). Serous tubal intra-epithelial carcinomas (STIC) have been detected in patients with BRCA 1 or 2 mutations and are considered as the most likely precursors of the high-grade serous ovarian cancer (HGSOC), which is the most common histological subtype in patients with EOC. A bilateral salpingo-oophorectomy is associated with a significant reduction in risk of developing EOC. According to various national guidelines, prophylactic bilateral salpingo-oophorectomy should be performed in the age group 40-45 years. As in patients with BRCA mutations, the prophylactic removal of the fallopian tubes is also performed in women without an increased genetic risk, for example, in surgical treatments of benign conditions. There is a current debate as to whether prophylactic or so-called opportunistic salpingectomy will influence the overall incidence of EOC in the coming years. Opponents of this theory warn of a higher surgical morbidity and the higher risk of a premature menopause through impaired vascular supply to the ovaries. The value of opportunistic salpingectomies has not yet been clarified since there are currently no systematic risk-benefit evaluations. This review will attempt to give an overview of the current body of evidence regarding the risks and benefits of opportunistic salpingectomies.

Specialized pathology review in patients with ovarian cancer: results from a prospective study.

BACKGROUND: A significant number of ovarian borderline tumors (BOTs) and metastatic nonovarian primaries are erroneously diagnosed as ovarian carcinomas. If BOTs are misdiagnosed as cancer, patients may not only experience nonbeneficial morbidity but may have to cope with an incorrect diagnosis of cancer for the rest of their lives. In cases of metastatic disease mistaken for an ovarian primary, more adequate therapeutic modalities may be withheld from some patients. Finally, clinical trials may be biased through unintended disregard of histological inclusion criteria. METHODS: Patients were recruited for central pathology review according to a translational subprotocol of a prospectively randomized phase 3 study led by the Arbeitsgemeinschaft Gynaekologische Onkologie (AGO) Study Group. All original slides were requested, and a specialized central pathology review was performed by experienced gynecopathologists. In cases of clinically relevant diagnostic discrepancies, the pathologist responsible for the original diagnosis was contacted. If a given discrepancy could not be resolved, a panel of experts was involved for clarification. RESULTS: Four hundred fifty-four patients with an original diagnosis of ovarian, tubal, or peritoneal epithelial carcinoma were recruited. In 6.8% (31 patients), a major diagnostic discrepancy of clinical relevance was found. Most frequently (15 patients), serous BOT had been misdiagnosed as invasive cancer. Ovarian metastases constituted the second most frequent misdiagnosis (13 patients). Minor discrepancies not affecting patient treatment were found in 28.2% (128 patients). CONCLUSIONS: Specialized central pathology review could help to avoid overtreatment of patients with BOT and inappropriate treatment of patients with ovarian metastases. The implementation of a specialized case review process may translate into enhanced patient safety in clinical trials of ovarian carcinomas. Furthermore, central pathology review may increase the rigor and ultimately the transferability of clinical research into practice and should therefore become a standard procedure in study protocols evaluating new therapies.

Ovarian borderline tumors in pre-menarche girls.

By reason of a new case of an ovarian mucinous borderline tumor (BOT) in a pre-menarche girl, a research of current literature was implemented. Low-grade malignant epithelial tumors are extremely rare in young children and, as far as we know, only a few case reports exist. The patients presented with vomiting, pain, and a swollen lower abdomen. Pre-operative diagnosis primarily consists of imaging techniques. At Stage Ia, the tumor is confined to the ovary without penetration of the capsule, no malignant ascites or peritoneal implants. Treatment consists of removal of the tumor combined with concurrent salpingo oophorectomy, appendectomy, omentectomy, and peritoneal lavage. Although the treatment recommendations are not uniform, basically, preservation of fertility is the main objective. The prognosis is very good, but recurrence is possible even after 10 years.

On the presence of serotonin in mammalian cardiomyocytes.

Pleiotropic effects of serotonin (5-HT) in the cardiovascular system are well documented. However, it remains to be elucidated, whether 5-HT is present in adult mammalian cardiomyocytes. To address this issue, we investigated the levels of 5-HT in blood, plasma, platelets, cardiac tissue, and cardiomyocytes from adult mice and for comparison in human right atrial tissue. Immunohistochemically, 5-HT was hardly found in mouse cardiac tissue, but small amounts could be detected in renal preparations, whereas adrenal preparations revealed a strong positive immunoreaction for 5-HT. Using a sensitive HPLC detection system, 5-HT was also detectable in the mouse heart and human atrium. Furthermore, we could identify 5-HT in isolated cardiomyocytes from adult mice. These findings were supported by detection of the activity of 5-HT-forming enzymes-tryptophan hydroxylase and aromatic L-amino acid decarboxylase-in isolated cardiomyocytes from adult mice and by inhibition of these enzymes with p-chlorophenylalanine and 3-hydroxybenzyl hydrazine. Addition of the first intermediate of 5-HT generation, that is 5-hydroxytryptophan, enhanced the 5-HT level and inhibition of monoamine oxidase by tranylcypromine further increased the level of 5-HT. Our findings reveal the presence and synthesis of 5-HT in cardiomyocytes of the mammalian heart implying that 5-HT may play an autocrine and/or paracrine role in the heart.

Histopathologic features of ovarian borderline tumors are not predictive of clinical outcome.

OBJECTIVES: Ovarian borderline tumors (BOTs) generally have an excellent prognosis, although recurrences and malignant transformation can occur. Our aim was to compare clinicopathologic features of BOT with clinical outcome. METHODS: In seventy consecutive BOTs clinicopathologic parameters, tumor cell proliferation (Ki67) and in selected cases KRAS, BRAF and p53 mutational status were analyzed with recurrence-free and overall survival as the endpoints. RESULTS: Sixty-one (87%) patients presented with FIGO stage I, 3 stage II, and 6 stage III. Thirty-four patients had serous and 36 mucinous BOT (30 intestinal and 6 endocervical subtypes). Non-invasive peritoneal implants occurred in 9 patients, and no invasive implants were observed. Recurrence-free and overall survival rates were 91% and 99%, respectively, at a mean follow-up of 63 months. Disease recurrence occurred in 6 cases (all FIGO stage I) including 3 serous, 1 mucinous-intestinal, and 2 mucinous-endocervical subtypes. Mean time to recurrence was 27 months (range 8-68). The recurrence rate following fertility-conserving surgery was 31% (5/16) compared to 2% (1/54) after bilateral salpingo-oophorectomy. Neither peritoneal implants (9/70), micropapillary pattern (2/34), microinvasion (4/70), nor increased tumor cell proliferation was associated with a higher recurrence rate. The frequency of KRAS or BRAF mutations was 50% (3/6 recurrences and 3/6 controls; 4 KRAS, 2 BRAF mutations). No p53 mutations (0/12) were detected in primary or recurrent BOTs. CONCLUSIONS: Histopathologic parameters were not predictive of BOT recurrence including previously suggested risk factors such as micropapillary pattern and microinvasion. However, fertility-conserving surgery and incomplete surgical staging were associated with a higher risk for recurrence.

Inverse expression of cystein-rich 61 (Cyr61/CCN1) and connective tissue growth factor (CTGF/CCN2) in borderline tumors and carcinomas of the ovary.

Members of the CCN [cystein-rich 61 (Cyr61)/connective tissue growth factor (CTGF)/nephroblastoma (NOV)] protein family are involved in the regulation of cellular proliferation, apoptosis, and migration and are also assumed to play a role in carcinogenesis. Therefore, we performed a retrospective study to investigate the immunohistochemical expression of both Cyr61 and CTGF in 92 borderline tumors (BOTs) and 107 invasive carcinomas of the ovary (IOCs). To determine their diagnostic and prognostic value, we correlated protein expression with clinicopathologic factors including overall and disease-free survival. Cyr61 and CTGF were found to be inversely expressed in both BOTs and IOCs, with a stronger expression of Cyr61 in IOCs. Moreover, Cyr61 was found to be preferentially expressed in high-grade serous carcinomas, whereas CTGF was found more frequently in low-grade serous carcinomas. Weak Cyr61 levels correlated with both low estrogen receptor and p53 expression (P=0.038, P=0.04, respectively). However, no association was observed between CTGF, estrogen receptor, and p53 expression levels in IOCs. Regarding prognosis, Cyr61 was found to be of no value, but the loss of CTGF was found to be associated with a poor prognosis in multivariate analysis of overall (relative risk 2.8; P=0.050) and disease-free (relative risk 2.3; P=0.031) survival. Cyr61 and CTGF are inversely expressed in BOTs and IOCs, and loss of CTGF independently indicates poor prognosis in IOCs.

Altered tumor formation and evolutionary selection of genetic variants in the human MDM4 oncogene.

A large body of evidence strongly suggests that the p53 tumor suppressor pathway is central in reducing cancer frequency in vertebrates. The protein product of the haploinsufficient mouse double minute 2 (MDM2) oncogene binds to and inhibits the p53 protein. Recent studies of human genetic variants in p53 and MDM2 have shown that single nucleotide polymorphisms (SNPs) can affect p53 signaling, confer cancer risk, and suggest that the pathway is under evolutionary selective pressure (1-4). In this report, we analyze the haplotype structure of MDM4, a structural homolog of MDM2, in several different human populations. Unusual patterns of linkage disequilibrium (LD) in the haplotype distribution of MDM4 indicate the presence of candidate SNPs that may also modify the efficacy of the p53 pathway. Association studies in 5 different patient populations reveal that these SNPs in MDM4 confer an increased risk for, or early onset of, human breast and ovarian cancers in Ashkenazi Jewish and European cohorts, respectively. This report not only implicates MDM4 as a key regulator of tumorigenesis in the human breast and ovary, but also exploits for the first time evolutionary driven linkage disequilibrium as a means to select SNPs of p53 pathway genes that might be clinically relevant.

Factors influencing the agreement on histopathological assessments of breast biopsies among pathologists.

AIMS: It has been recommended that the histopathology results of core biopsies of the breast are categorized according to the B-categorization scheme. We measured the interobserver variability of the B-categorization of core biopsies of the breast. METHODS AND RESULTS: Core biopsies were taken among 765 women at the University of Halle between 2006 and 2008. All histological slides were reviewed in a blinded fashion by two experienced breast pathologists. We calculated observed and chance-corrected agreements (kappa) and 95% confidence intervals (CI). The prevalence of B3-B5 biopsies was 41.6%. The observed and weighted kappa agreement of the five-level B-categorization scheme was 0.87 (95% CI: 0.84 -0.89) and 0.89 (95% CI: 0.89-0.91), respectively. The most frequent disagreement was between B2 and B3 (47 of 103 disagreements, 45.6%). Overall, 49.5% of all disagreements were clinically relevant disagreements that would imply different therapeutic strategies. Agreement was modified by referral group, Breast Imaging Reporting and Data System (BIRADS) level, radiological breast density, imaging guidance and application of immunohistological staining. CONCLUSIONS: Interobserver agreement of the B-categorization scheme was high and was modified by referral status, level of radiological suspicion of breast cancer, breast density, imaging guidance of core biopsies and requirement of additional immunohistological staining.

Adjuvant low single dose cisplatin-based concurrent radiochemotherapy of oral cavity and oropharynx carcinoma: impact of extracapsular nodal spread on distant metastases.

BACKGROUND: The aim of this study was to analyze the prognostic importance of extracapsular nodal spread (ECS) in patients with locally advanced squamous cell carcinoma (SCC) of the oral cavity or oropharynx, and the impact of adjuvant low single dose cisplatin-based radiochemotherapy on distant metastases-free survival (DMFS). PATIENTS AND METHODS: The study population was selected from 195 patients with high-risk oral cavity or oropharyngeal cancer, who had either adjuvant radiotherapy (RT) or radiochemotherapy (RCT) between January 1, 1997 and December 31, 2006, at the University Clinic of Radiation Oncology of the Martin-Luther-University Halle-Wittenberg. A total of 42 matched pairs of patients with UICC stage III-IVa,b disease were analyzed. The patients were matched (one to one) according to tumor site, sex, T stage, N stage, ECS, resection margin status, and Karnofsky performance status. To analyze the correlation between the treatment modality (RT vs. RCT) and the impact of ECS on DMFS, the Cox proportional hazard model was used. Survival rates were calculated using the Kaplan-Meier method. RESULTS: There was a strong correlation between the degree of nodal involvement and ECS (pN1: 33%; pN2b: 45%; pN2c: 71%). Moreover, the 5-year locoregional control rates (LC) in patients with ECS were 76% vs. 63% (n.s.) for RT and RCT, respectively. However, for patients without ECS, the LC was more favorable after RCT (RT vs. RCT: 62% vs. 88%, p < 0.05). DMFS again was better after RT, and this observation was independent of the presence or absence of ECS. Finally, in multivariate analyses, the presence of ECS significantly decreased the DMFS (p = 0.04, hazard ratio (HR) 2.64). CONCLUSIONS: Patients with ECS have an increased risk of distant metastases. Adjuvant low single dose cisplatin-based concurrent chemotherapy seems to have no influence on occult microscopic systemic disease.

Adherence to Newly Implemented Tamoxifen Therapy for Breast Cancer Patients in Rural Western Ethiopia.

INTRODUCTION: Endocrine therapy for breast cancer (BC) patients is highly underutilized in rural Ethiopia and other African countries. OBJECTIVE: This study aims to assess the feasibility of and adherence to tamoxifen therapy in rural Ethiopia. METHODS: We ascertained the hormone receptor (HR) status in 101 women diagnosed with BC from January 2010 to December 2015 and who had surgery in Aira Hospital, in rural Ethiopia. From 2013, tamoxifen was offered to patients with HR-positive (HR+) tumors. Prescription refill records and a structured questionnaire were used to assess receipt of and adherence to tamoxifen. RESULTS: Of the 101 BC patients tested for HR status during the study period, 66 (65%) patients were HR+ and were eligible for tamoxifen treatment. However, 15 of the HR+ patients died before tamoxifen became available in 2013. Of the remaining 51 HR+ patients, 26 (51%) initiated tamoxifen but only 9 of them (35%) adhered to therapy (medication possession rate ≥80%, median observation 16.2 months). After 1 year, 52% of the patients were still adherent, and 9 patients had discontinued therapy. The reasons for non-initiation of tamoxifen included patient factors (n = 5), including financial hardship or lack of transportation, and health care provider factors (n = 12). CONCLUSIONS: Endocrine therapy for BC patients seems feasible in rural Western Ethiopia, although non-adherence due to financial hardship and a less developed health care infrastructure remains a major challenge. We postulate that the implementation of breast nurses could reduce patient and health system barriers and improve initiation of and adherence to endocrine treatment.

Nucleolin as activator of human papillomavirus type 18 oncogene transcription in cervical cancer.

High risk human papillomaviruses (HPVs) are central to the development of cervical cancer and the deregulated expression of high risk HPV oncogenes is a critical event in this process. Here, we find that the cell protein nucleolin binds in a sequence-specific manner to the HPV18 enhancer. The DNA binding activity of nucleolin is primarily S phase specific, much like the transcription of the E6 and E7 oncoproteins of HPV18 in cervical cancer cells. Antisense inactivation of nucleolin blocks E6 and E7 oncogene transcription and selectively decreases HPV18(+) cervical cancer cell growth. Furthermore, nucleolin controls the chromatin structure of the HPV18 enhancer. In contrast, HPV16 oncogene transcription and proliferation rates of HPV16(+) SiHa cervical cancer cells are independent of nucleolin activity. Moreover, nucleolin expression is altered in HPV18(+) precancerous and cancerous tissue from the cervix uteri. Whereas nucleolin was homogeneously distributed in the nuclei of normal epithelial cells, it showed a speckled nuclear phenotype in HPV18(+) carcinomas. Thus, the host cell protein nucleolin is directly linked to HPV18-induced cervical carcinogenesis.

Cardiac overexpression of the human 5-HT4 receptor in mice.

Serotonin (5-HT) exerts pleiotropic effects in the human cardiovascular system. Some of the effects are thought to be mediated via 5-HT(4) receptors, which are expressed in the human atrium and in ventricular tissue. However, a true animal model to study these receptors in more detail has been hitherto lacking. Therefore, we generated, for the first time, a transgenic (TG) mouse with cardiac myocyte-specific expression of the human 5-HT(4) receptor. RT-PCR and immunohistochemistry revealed expression of the receptor at the mRNA and protein levels. Stimulation of isolated cardiac preparations by isoproterenol increased phospholamban phosphorylation at Ser(16) and Thr(17) sites. 5-HT increased phosphorylation only in TG mice but not in wild-type (WT) mice. Furthermore, 5-HT increased contractility in isolated perfused hearts from TG mice but not WT mice. These effects of 5-HT could be blocked by the 5-HT(4) receptor-selective antagonist GR-125487. An intravenous infusion of 5-HT increased left ventricular contractility in TG mice but not in WT mice. Similarly, the increase in contractility by 5-HT in isolated cardiomyocytes from TG mice was accompanied by and probably mediated through an increase in L-type Ca(2+) channel current and in Ca(2+) transients. In intact animals, echocardiography revealed an inotropic and chronotropic effect of subcutaneously injected 5-HT in TG mice but not in WT mice. In isolated hearts from TG mice, spontaneous polymorphic atrial arrhythmias were noted. These findings demonstrate the functional expression of 5-HT(4) receptors in the heart of TG mice, and a potential proarrhythmic effect in the atrium. Therefore, 5-HT(4) receptor-expressing mice might be a useful model to mimic the human heart, where 5-HT(4) receptors are present and functional in the atrium and ventricle of the healthy and failing heart, and to investigate the influence of 5-HT in the development of cardiac arrhythmias and heart failure.