From microbiota toward gastro-enteropancreatic neuroendocrine neoplasms: Are we on the highway to hell?

Gut microbiota is represented by different microorganisms that colonize the intestinal tract, mostly the large intestine, such as bacteria, fungi, archaea and viruses. The gut microbial balance has a key role in several functions. It modulates the host’s metabolism, maintains the gut barrier integrity, participates in the xenobiotics and drug metabolism, and acts as protection against gastro-intestinal pathogens through the host’s immune system modulation. The impaired gut microbiota, called dysbiosis, may be the result of an imbalance in this equilibrium and is linked with different diseases, including cancer. While most of the studies have focused on the association between microbiota and gastrointestinal adenocarcinomas, very little is known about gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs). In this review, we provide an overview concerning the complex interplay between gut microbiota and GEP NENs, focusing on the potential role in tumorigenesis and progression in these tumors.

     

Androgen-dependent pathology demonstrates myopathic contribution to the Kennedy disease phenotype in a mouse knock-in model

Kennedy disease, a degenerative disorder characterized by androgen-dependent neuromuscular weakness, is caused by a CAG/glutamine tract expansion in the androgen receptor (Ar) gene. We developed a mouse model of Kennedy disease, using gene targeting to convert mouse androgen receptor (AR) to human sequence while introducing 113 glutamines. AR113Q mice developed hormone and glutamine length-dependent neuromuscular weakness characterized by the early occurrence of myopathic and neurogenic skeletal muscle pathology and by the late development of neuronal intranuclear inclusions in spinal neurons. AR113Q males unexpectedly died at 2-4 months. We show that this androgen-dependent death reflects decreased expression of skeletal muscle chloride channel 1 (CLCN1) and the skeletal muscle sodium channel alpha-subunit, resulting in myotonic discharges in skeletal muscle of the lower urinary tract. AR113Q limb muscles show similar myopathic features and express decreased levels of mRNAs encoding neurotrophin-4 and glial cell line-derived neurotrophic factor. These data define an important myopathic contribution to the Kennedy disease phenotype and suggest a role for muscle in non-cell autonomous toxicity of lower motor neurons.     

PRRT: identikit of the perfect patient

Reviews in Endocrine and Metabolic Disorders - Peptide receptor radionuclide therapy (PRRT) has been strengthened since the publication of NETTER-1. Nevertheless, the correct positioning in the...     

Dietary vitamin D₃ and 1,25-dihydroxyvitamin D₃ (calcitriol) exhibit equivalent anticancer activity in mouse xenograft models of breast and prostate cancer

1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3) or calcitriol], the hormonally active vitamin D metabolite, exhibits anticancer actions in models of breast cancer and prostate cancer. Because CYP27B1 (1α-hydroxylase), the enzyme catalyzing 1,25(OH)(2)D(3) formation in the kidney, is also expressed in extrarenal tissues, we hypothesize that dietary vitamin D(3) will be converted to 25(OH)D(3) in the body and then to 1,25(OH)(2)D(3) locally in the cancer microenvironment in which it will exert autocrine/paracrine anticancer actions. Immunocompromised mice bearing MCF-7 breast cancer xenografts showed significant tumor shrinkage (>50%) after ingestion of a vitamin D(3)-supplemented diet (5000 IU/kg) compared with a control diet (1000 IU/kg). Dietary vitamin D(3) inhibition of tumor growth was equivalent to administered calcitriol (0.025, 0.05, or 0.1 μg/mouse, three times a week). Both treatments equivalently inhibited PC-3 prostate cancer xenograft growth but to a lesser extent than the MCF-7 tumors. Calcitriol at 0.05 μg and 0.1 μg caused modest but statistically significant increases in serum calcium levels indicating that the dietary vitamin D(3) comparison was to a maximally safe calcitriol dose. Dietary vitamin D(3) did not increase serum calcium, demonstrating its safety at the concentration tested. The vitamin D(3) diet raised circulating 1,25 dihydroxyvitamin D levels and did not alter CYP27B1 mRNA in the kidney but increased it in the tumors, suggesting that extrarenal sources including the tumors contributed to the elevated circulating 1,25 dihydroxyvitamin D(3). Both calcitriol and dietary vitamin D(3) were equipotent in suppressing estrogen synthesis and signaling and other proinflammatory and growth signaling pathways. These preclinical data demonstrate the potential utility of dietary vitamin D(3) supplementation in cancer prevention and therapy.     

"Present and future of immunotherapy in Neuroendocrine Tumors"

Reviews in Endocrine and Metabolic Disorders - Immunotherapy, so promising in many neoplasms, still does not have a precise role in the treatment of neuroendocrine neoplasms (NENs). In this...     

Characterization and sub-cellular localization of SS1R,SS2R,and SS5R in human late-stage prostate cancer cells: Effect of mono- and bi-specific somatostatin analogs on cell growth

Somatostatin (SST) and SST receptors (SS1R, SS2R, SS3R, SS4R and SS5R) appear to play a significant role in the progression of human prostate cancer (PCa), which is associated with heterogeneity of SSRs expression and specific cell localization as we already demonstrated in the LNCaP cell line, an in vitro model of human androgen-dependent PCa. In this study, PC-3 and DU-145 human castration-resistant PCa cells were found to express all SSRs, while LNCaP expressed all but SS4R. A 48-h treatment with BIM-23244 (SS2R/SS5R) or BIM-23926 (SS1R) SST analogs was more effective in inhibiting cell proliferation, compared to BIM-23120 (SS2R), BIM-23206 (SS5R) and BIM-23704 (SS1R/SS2R). BIM-23926 (SS1R) treatment increased the amount of p21 and decreased phosphorylated (p) ERK1/2. BIM-23244 (SS2R/SS5R) led to p21 increment only in PC-3 cells, and to pERK1/2 reduction in both cell lines. SS1R/SS2R and SS2R/SS5R receptor dimers were natively present on cell membrane and their amount was increased by BIM-23704 (SS1R/SS2R) or BIM-23244 (SS2R/SS5R) treatment, respectively. SS1R, SS2R and SS5R were differently distributed among nuclear, lysosomal and microsomal compartment, according to their different recycling dynamics. These results show that, in PC-3, DU-145 and LNCaP cells, activation of SS1R and SS2R/SS5R leads to relevant antiproliferative effects.     

Echocardiographic and Electrocardiographic Characteristics of Male and Female Squirrel Monkeys (Saimiri spp.)

Cardiomyopathy is a leading cause of mortality in aging squirrel monkeys (Saimiri spp.). However, data regarding echocardiographic measures obtained from clinically healthy nonsedated squirrel monkeys have not been published, and few electrocardiographic data are available. Here we obtained echocardiographs without sedation and electrocardiographs with minimal sedation from 63 clinically healthy squirrel monkeys that ranged from 3 to 20 y in age. 2D and M-mode echocardiography were performed on nonsedated monkeys to determine the left ventricular internal diameters at systole and diastole and the ejection fraction. Electrocardiography was performed under sedation with ketamine (15 mg/kg). Parameters evaluated included heart rate; P-wave duration; lengths of the PR, QRS, and QT intervals; R-wave amplitude, and P-wave amplitude. Initial physical examination, electrocardiography, and echocardiography indicated normal cardiac function for all monkeys. The objectives of this study were to provide reference values for nonsedated echocardiography and ketamine-sedated electrocardiography of clinically normal squirrel monkeys and to determine correlates of age and sex in these values.Squirrel monkeys (Saimiri spp.) are the most commonly studied neotropical nonhuman primate in biomedical research in the United States.² Heart failure due to cardiomyopathy is a leading cause of mortality in squirrel monkeys, particularly in large colonies of aging animals. The initial case report of dilative cardiomyopathy in a squirrel monkey came from our colony,²⁶ and in subsequent years, cardiomyopathy and heart failure have been the primary health concern in the geriatric population at our institution. In reviewing necropsy records over a 4-y span (census of approximately 70), we noted that 9 adult squirrel monkeys were euthanized for medical reasons related to cardiac changes. Another institution reported cases of dilative and hypertrophic cardiomyopathy in adult female Bolivian squirrel monkeys (S. bolivinesis) and found that 23 of 88 adult animals had lesions consistent with heart failure or cardiomegaly on necropsy.³ Affected squirrel monkeys often do not present with clinical signs until cardiomegaly is severe, and often euthanasia is performed due to the lack of treatment options in the late stage of disease.Squirrel monkey cardiomyopathy has not been characterized as primarily hypertrophic or dilative, and the causative agent is currently unknown.³ Potential causes of cardiomyopathy in these species include Trypanosoma cruzi,^6,16 taurine deficiency,^19,26 virus-mediated myocarditis,¹ and captivity,⁸ but the evidence is unclear. Current diagnostic methods available for the detection of cardiomyopathy include echocardiography, electrocardiography, radiology, and physical examination. Echocardiography enables the evaluation of cardiac function through the estimation of ejection fraction, chamber size, and wall thickness and the evaluation of ventricular outflow track. This noninvasive diagnostic method can be performed on nonsedated squirrel monkeys accustomed to handling. Anesthetics can cause cardiovascular and respiratory system depression, resulting in jeopardized cardiac function, confounding hemodynamic data, or underestimation of left ventricular function; therefore, performing cardiac evaluations on nonsedated animals may be preferable.²⁸ Electrocardiography provides insight into conductive abnormalities within the normal or diseased heart. However, changes can be very subtle and difficult to detect, and good-quality tracings are therefore necessary.⁹ Sedation is often used to minimize muscle movement and aid in electrode placement.²⁵Few data regarding normal echocardiographic and electrocardiographic reference ranges in squirrel monkeys are available.^2,3,27 Previously published echocardiographic data were obtained from animals sedated with ketamine and xylazine, and electrocardiographic data were obtained after sedation with either sodium thiopental or ketamine and xylazine.^2,3,27 Furthermore, these previous studies assessed only single-sex populations or animals within a narrow age range, and the subspecies of Saimiri was mixed or not reported.^2,3,27 In the current study, we characterized echocardiographic data obtained from nonsedated, clinically healthy male and female Guyanese squirrel monkeys of various ages. In addition, we performed electrocardiography on these same monkeys after their sedation (15 mg/kg ketamine hydrochloride). These data establish new reference ranges for echocardiographic and electrocardiographic diagnostics in squirrel monkeys and may facilitate improved assessment of cardiac function in both healthy and diseased squirrel monkeys.     

Optimization of flow reserve measurement using SPECT technology to evaluate the determinants of coronary microvascular dysfunction in diabetes

Purpose

The aim of this study was to validate a new method to measure regional myocardial perfusion reserve (MPR) with technetium-labelled tracers in patients with type 2 diabetes mellitus (DM2).

Methods

A total of 40 consecutive DM2 patients without history of coronary artery disease (CAD) and 7 control subjects were recruited. Dipyridamole myocardial blood flow index (MBF) was assessed by measuring first transit counts in the pulmonary artery and myocardial count rate from gated SPECT images using ^99mTc-labelled tracers. The corresponding MBF index was estimated 2 h later according to the same procedure. Regional myocardial perfusion reserve (MPR) was defined as the ratio between dipyridamole and baseline MBF using a 17-segment left ventricular (LV) model. Coronary flow reserve (CFR) was estimated by transthoracic contrast echo Doppler monitoring of flow velocity in the left anterior descending coronary artery (LAD) during the same session.

Results

Estimated MPR was higher in control subjects than in patients (3.36?±?0.66 vs 1.91?±?0.61, respectively, p?<?0.01). In patients, LAD CFR and LAD MPR were 2.01?±?0.78 vs 1.93?±?0.63, respectively (p?=?ns). The agreement between the two techniques was documented by their close correlation (r?=?0.92, p?<?0.001) and confirmed by the Bland-Altman analysis. Reversible perfusion defects occurred in 13 patients (32%) who showed similar MPR values as the remaining 27 (2.10?±?0.71 vs 1.83?±?0.71, respectively, p?=?ns). Finally, MPR was closely correlated with age (r?=??0.50, p?<?0.01) and time elapsed from the diagnosis of DM2 (r?=??0.51, p?<?0.01).

Conclusion

LV regional MPR can be accurately estimated with the broadly available single photon technology. Application of this method to DM2 patients documents the presence of a microvascular dysfunction homogeneously distributed throughout the LV walls and most frequently not associated with reversible perfusion defects.     

Uterine Leiomyoma in a Guyanese Squirrel Monkey (Saimiri sciureus sciureus)

An adult female squirrel monkey (Saimiri sciureus) presented with a 3.0 × 2.5 cm firm mass palpable within the caudal abdomen. Differentiation of the organs or structures involved with the mass could not be achieved with radiography or ultrasonography. Exploratory laparotomy revealed a mass within the lumen of the uterus; the mass was removed by partial hysterectomy. On gross examination, the mass was a focally extensive, unencapsulated, firm, solitary tumor. Histologic examination revealed that the mass was composed of interlacing bundles of smooth muscle cells with little fibrous stroma. The cells were elongated with poorly delineated borders and cigar-shaped nuclei, each containing a single, small nucleolus. Fewer than 1 mitosis per 20 high-power (magnification, × 400) fields were present. These gross and histologic findings supported a diagnosis of uterine leiomyoma. Although leiomyomas are the most common tumor of the reproductive tract in nonhuman primates, to our knowledge the current lesion is the first uterine leiomyoma reported to occur in a squirrel monkey.Leiomyomas are discrete, benign neoplasms of smooth muscle which frequently occur in the viscera of the gastrointestinal tract and uterus.² They have also been reported to occur in the ovary,¹³ vulva,⁷ and cervix.⁷ Leiomyomas of the female genitalia are among the most frequently encountered tumors of the reproductive system in almost all domestic animal species.⁷ In humans, they are the most common gynecologic neoplasm, clinically affecting as many as 30% of women of reproductive age.¹² Although most uterine leiomyomas are asymptomatic and do not require therapy, signs that can be seen in affected patients include abnormal uterine bleeding,¹² anemia,²³ bowel dysfunction,¹² increased urinary frequency and urgency,¹² and decreased efficiency of subsequent assisted-reproduction cycles.¹⁵ The effect of uterine leiomyomas on overall fertility in women is under debate. Although most patients remain asymptomatic, it is important to differentiate leiomyomas from their malignant counterparts, leiomyosarcomas. The differentiation between the 2 types of smooth muscle tumors can generally be made with reasonable certainty according to gross and light microscopic features. More specifically, mitotic index and determination of nucleolar organizer regions have both been shown to be useful in differentiating leiomyomas from leiomyosarcomas.⁷Few neoplasms of the reproductive tract of nonhuman primates have been reported. In a worldwide literature review of 783 spontaneous neoplasms that occurred in nonhuman primates, only 1.0% were cervical, 1.6% involved the ovaries, and 2.0% were uterine tumors (94% of which were leiomyomas).^3,5 In the current report, we describe the first documented case of a uterine leiomyoma in a squirrel monkey (Saimiri sciureus).