SRC homology-2-containing protein tyrosine phosphatase-1 restrains cell proliferation in human medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare tumor originating from thyroid parafollicular C cells, where, in the inherited form, constitutive activation of the RET protooncogene is responsible for unrestrained cell proliferation. We previously demonstrated that somatostatin (SRIF) reduces cell growth in the human MTC cell line TT, which expresses all SRIF receptor (SSTR) subtypes and responds differently to selective SSTR agonists. The antiproliferative mechanism of SRIF and its analogs in MTC is still unclear. Src homology-2-containing protein tyrosine phosphatase-1 (SHP-1), a cytoplasmic protein tyrosine phosphatase (PTP), is activated by somatotropin release-inhibiting factor and reduces mutated RET autophosphorylation in a heterologous system. In this study, we explore the role of PTP activation, in particular of SHP-1, in TT cells, where RET is constitutively activated. In TT cells, SRIF stimulated the PTP activity of SHP-1, which was associated with proliferation inhibition and with reduction in the MAPK pathway activation. Blockade of PTP activity with sodium orthovanadate induced cell proliferation and MAPK phosphorylation and blunted the inhibitory effects of SRIF. Moreover, SHP-1 associates with SSTR2 depending on its activation. By using a MAPK kinase inhibitor, we demonstrated that TT cell growth depends on MAPK pathway activation. Furthermore, in TT cells overexpressing SHP-1, cell proliferation and MAPK signaling were strongly down-regulated, whereas in TT cells transfected with a dominant negative form of SHP-1, cell proliferation and MAPK signaling were markedly induced. Our data demonstrate that SRIF inhibitory effects on TT cell proliferation are mediated, at least in part, by SHP-1, which acts through a MAPK-dependent mechanism.     

Molecular networking prospection and characterization of terpenoids and C15-acetogenins in Brazilian seaweed extracts

Molecular networking (MN) can efficiently dereplicate extracts and pure compounds. Red algae of the genus Laurencia are rich in halogenated secondary metabolites, mainly sesquiterpenes and C₁₅-acetogenins. Brown algae of the genus Dictyopteris produce mainly C₁₁-hydrocarbons, sesquiterpenes and sulfur-containing compounds, while Dictyota and Canistrocarpus are reported to contain mainly diterpenes. This study performs an exploratory MN analysis of 14 extracts from algae collected in Brazil (including the oceanic islands) and characterizes the secondary metabolites from the analyzed species. The extracts and some isolated metabolites were analyzed by LC-MS using the FastDDA algorithm, and the MS/MS spectra were submitted to GNPS and displayed in Cytoscape 3.5.1. The GNPS platform generated 68 individual nodes and nine family networks. The MN exploratory analysis indicated chemical differences among species, and also in sampling sites for the same species. For some extracts, it was possible to identify mass values that could correspond to terpenoids and C₁₅-acetogenins that have already been isolated from those or related species. An interesting chemodiversity was highlighted between Laurencia catarinensis from two nearby islands, and this was revealed and was also suggested by the family networks. Many nodes in the MN could not be characterized, and these metabolites can be used as targets for isolation in future works.

Molecular networking of Brazilian marine algae.     

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.

     

Adrenal cavernous hemangioma: a case report

Background

Adrenal cavernous hemangiomas are very rare benign tumors that usually present as incidental findings on abdominal imaging. Preoperative differential diagnosis from other benign or malignant adrenal neoplasms may be challenging.

Case presentation

A 70-year old man was referred for an 8-cm abdominal mass incidentally discovered on a contrast-enhanced computed tomography (CT) performed to investigate a pulmonary nodule. Biochemical tests ruled out any endocrine dysfunction and iodine 123 metaiodobenzylguanidine whole body scintiscan single-photon emission CT excluded a pheocromocitoma. Findings on magnetic resonance imaging were non-specific and the patient was elected for a left adrenalectomy. Histopathological diagnosis revealed a cavernous hemangioma. A portion of the resected tissue was tested for drug sensitivity to mitotane, doxorubicin, and sunitinib.

Conclusions

Adrenal hemangioma is a rare disease but should be included in the differential diagnosis of adrenal tumors. The surgical resection is generally required to exclude malignant disease, resolve pressure-related symptoms, and prevent retroperitoneal hemorrhage. Although specific features in diagnostic imaging are often lacking, if the diagnosis is established preoperatively a laparoscopic adrenalectomy can be performed due to the benign nature of the lesion. Doxorubicin and sunitinib were both capable of reducing primary culture cell viability, this suggest that similar drugs may be useful in the medical treatment of adrenal hemangiomas.

     

Pasireotide, a multiple somatostatin receptor subtypes ligand, reduces cell viability in non-functioning pituitary adenomas by inhibiting vascular endothelial growth factor secretion

Somatostatin (SRIF) analogs have been employed in medical therapy of non-functioning pituitary adenomas (NFA), with contrasting results. Previous evidence showed that SRIF can exert its antiproliferative effects by reducing vascular endothelial growth factor (VEGF) secretion and action, and that VEGF expression may be related to pituitary tumor growth. The aim of our study was to clarify the possible effects of a multireceptor SRIF ligand on VEGF secretion and cell proliferation in human NFA primary cultures. We assessed the expression of SRIF receptors (SSTR1-5), the in vitro effects on VEGF secretion, and on cell viability of SRIF and of the stable SRIF analog pasireotide (SOM230), which activates SSTR1, 2, 3, and 5. Twenty-five NFA were examined by RT-PCR for expression of alpha-subunit, SSTR, VEGF, and VEGF receptors 1 (VEGF-R1) and 2 (VEGF-R2). Primary cultures were tested with SRIF and with pasireotide. All NFA samples expressed alpha-sub, VEGF and VEGFR-1 and 2, while SSTR expression pattern was highly variable. Two different groups were identified according to VEGF secretion inhibition by SRIF. VEGF secretion and cell viability were reduced by SRIF and pasireotide in the 'responder' group, but not in the 'non-responder' group, including NFA expressing SSTR5. SRIF and pasireotide completely blocked forskolin-induced VEGF secretion. In addition, SRIF and pasireotide completely abrogated the promoting effects of VEGF on NFA cell viability. Our data demonstrate that pasireotide can inhibit NFA cell viability by inhibiting VEGF secretion, and suggest that the multireceptor-SSTR agonist pasireotide might be useful in medical therapy of selected NFA.     

Dosimetry in dental radiology: comparison of spiral computerized tomography and orthopantomography]

INTRODUCTION: Dental diagnosis still depends largely on diagnostic imaging for correct anatomical and radiological assessment. Many studies confirm the risk of ionizing radiations, especially if used in pediatric populations and with suboptimal control. We compared the doses absorbed by the dentomaxillary area in Spiral CT and panoramic radiography examinations. MATERIAL AND METHODS: Doses were measured at critical organs in neck, ocular and intracranial regions with lithium fluoride dosimeters calibrated on the national standard and then positioned on an anthropomorphic Rando phantom made of tissue-equivalent material covering a skeleton. Multiple measurements were made during Spiral CT with the Dentascan software and panoramic radiography, to calculate mean absorbed doses for both examinations. Acquisition technical parameters were similar to those used in vivo. RESULTS: The parotid, cerebellum and thyroid gland were the most irradiated organs with panoramic radiography, with the addition of the mandible with Spiral CT. The gonads did not receive major doses. CONCLUSIONS: Our dose measurements demonstrate that patients receive smaller doses with panoramic radiography than with Spiral CT with Dentascan. After allowing for some variations from instrumental differences, they are in substantial agreement with literature data. Further investigations are needed considering the radiobiological risk related to the growing spread of Dentascan examinations.     

Somatostatin analogs in vitro effects in a growth hormone-releasing hormone-secreting bronchial carcinoid

A 29-yr-old woman presented with acromegaly, pituitary gland enlargement, and an isolated pulmonary mass of 3.3 cm in diameter, which displayed a very high tracer uptake after OctreoScan. Plasma GHRH levels were markedly elevated. The patient underwent left lung upper lobectomy, and histopathology disclosed a bronchial atypical carcinoid. The tissue was examined for somatostatin (SRIH) receptor subtypes (SSTRs) 1-5 expression by RT-PCR. Cultured tumor cells were treated with SRIH, lanreotide (BIM-23014), or SRIH analogs selective for SSTR2 (BIM-23120), SSTR5 (BIM-23206), or SSTR1 (BIM-23926). GHRH was measured in the medium after 6 h, and cell viability was assessed after 48 h. RT-PCR analysis showed expression of SSTR1, -2, and -5. GHRH secretion was significantly reduced by SRIH (-50%), Lan (-35%), as well as by the SSTR2, SSTR5, and SSTR1 selective agonists (-55, -75, and -20%, respectively), whereas cell viability was not affected. Our data show SSTR expression in a GHRH-secreting bronchial carcinoid and provide evidence that, in vitro, selective SSTR activation differently inhibit ectopic GHRH secretion. These findings suggest that SSTR-specific SRIH analogs may be useful in the medical therapy of GHRH-secreting bronchial carcinoids.