Correlation between targeted RNAseq signature of breast cancer CTCs and onset of bone-only metastases.

BACKGROUND: Bone is the most frequent site of metastases from breast cancer (BC), but no biomarkers are yet available to predict skeletal dissemination. METHODS: We attempted to identify a gene signature correlated with bone metastasis (BM) onset in circulating tumour cells (CTCs), isolated by a DEPArray-based protocol from 40 metastatic BC patients and grouped according to metastasis sites, namely "BM" (bone-only), "ES" (extra-skeletal) or BM + ES (bone + extra-skeletal). RESULTS: A 134-gene panel was first validated through targeted RNA sequencing (RNAseq) on sub-clones of the MDA-MB-231 BC cell line with variable organotropism, which successfully shaped their clustering. The panel was then applied to CTC groups and, in particular, the "BM" vs "ES" CTC comparison revealed 31 differentially expressed genes, including MAF, CAPG, GIPC1 and IL1B, playing key prognostic roles in BC. CONCLUSION: Such evidence confirms that CTCs are suitable biological sources for organotropism investigation through targeted RNAseq and might deserve future applications in wide-scale prospective studies.

Uterine carcinosarcoma: An overview.

Uterine carcinosarcoma (UCS), also known as malignant mixed Müllerian tumor, is a rare gynecological malignancy characterized by poor prognosis. This "biphasic" neoplasm presents an admixture of epithelial and mesenchymal/sarcomatoid tumor cells which partially share their molecular signature and exhibit a typical epithelial-to-mesenchymal transition gene expression profile. Due to the rarity of this cancer, at present there is a scarcity of specific treatment guidelines. Surgical resection remains the best curative option for localized disease, whereas the addition of peri-operative radiotherapy, chemotherapy and chemoradiation has been shown to further improve disease outcomes. In the metastatic setting, palliative chemotherapy is currently the treatment of choice, although no consensus exists about the best regimen to be delivered. Besides standard treatment options for the advanced disease, mechanistic insights into UCS pathogenesis and identification of its histopathological and molecular features boosted the development of novel, and potentially more effective, therapeutic agents, that will be here discussed.

Susceptibility to ischaemic heart disease: Focusing on genetic variants for ATP-sensitive potassium channel beyond traditional risk factors.

AIMS: Ischaemic heart disease is classically associated with coronary artery disease. Recent evidences showed the correlation between coronary microvascular dysfunction and ischaemic heart disease, even independently of coronary artery disease. Ion channels represent the final effectors of blood flow regulation mechanisms and their genetic variants, in particular of Kir6.2 subunit of the ATP-sensitive potassium channel (KATP), are reported to be involved in ischaemic heart disease susceptibility. The aim of the present study is to evaluate the role of KATP channel and its genetic variants in patients with ischaemic heart disease and evaluate whether differences exist between coronary artery disease and coronary microvascular dysfunction. METHODS: A total of 603 consecutive patients with indication for coronary angiography due to suspected myocardial ischaemia were enrolled. Patients were divided into three groups: coronary artery disease (G1), coronary microvascular dysfunction (G2) and normal coronary arteries (G3). Analysis of four single nucleotide polymorphisms (rs5215, rs5216, rs5218 and rs5219) of the KCNJ11 gene encoding for Kir6.2 subunit of the KATP channel was performed. RESULTS: rs5215 A/A and G/A were significantly more represented in G1, while rs5215 G/G was significantly more represented in G3, rs5216 G/G and C/C were both more represented in G3, rs5218 C/C was more represented in G1 and rs5219 G/A was more represented in G1, while rs5219 G/G was significantly more represented in G2. At multivariate analysis, single nucleotide polymorphism rs5215_G/G seems to represent an ischaemic heart disease independent protective factor. CONCLUSIONS: These results suggest the potential role of KATP genetic variants in ischaemic heart disease susceptibility, as an independent protective factor. They may lead to a future perspective for gene therapy against ischaemic heart disease.

Bone Metastases in Neuroendocrine Tumors: Molecular Pathogenesis and Implications in Clinical Practice.

Skeletal colonization is often regarded as a rare event in patients with neuroendocrine tumors (NETs) although both national registries and retrospective series report an incidence of bone metastases as high as 20% in subjects with advanced disease. While the biological mechanisms leading to bone metastatic colonization in NETs have been poorly investigated so far, key steps of osteotropic mechanisms, including the epithelial-to-mesenchymal transition, preparation of the premetastatic niche, migration of circulating tumor cells towards the bone marrow as well as the resulting alterations of the skeletal metabolism, are likely to operate also during the development of NET bone metastases. The skeleton involvement by NETs has a detrimental impact on both quality of life and patients' prognosis, leading to pain in the majority of symptomatic subjects. While it is currently unclear whether or not the earlier recognition of bone involvement by PET/CT imaging techniques employing 68Ga-DOTA-conjugated peptides might improve outcomes through the exploitation of timely treatments, the management of bone-colonizing NETs is today based only on clinical experience from other osteotropic tumors. Here, we summarize the fundamental molecular mechanisms driving bone colonization and revisit both established and novel treatments for patients with bone metastatic NETs.

Application of "omics" sciences to the prediction of bone metastases from breast cancer: State of the art.

Breast cancer (BC) is the most frequent malignancy and the first cause of cancer-related death in women. The majority of patients with advanced BC develop skeletal metastases which may ultimately lead to serious complications, termed skeletal-related events, that often dramatically impact on quality of life and survival. Therefore, the identification of biomarkers able to stratify BC patient risk to develop bone metastases (BM) is fundamental to define personalized diagnostic and therapeutic strategies, possibly at the earliest stages of the disease. In this regard, the advent of "omics" sciences boosted the investigation of several putative biomarkers of BC osteotropism, including deregulated genes, proteins and microRNAs. The present review revisits the current knowledge on BM development in BC and the most recent studies exploring potential BM-predicting biomarkers, based on the application of omics sciences to the study of primary breast malignancies.

Liquid Biopsy as a Tool Exploring in Real-Time Both Genomic Perturbation and Resistance to EGFR Antagonists in Colorectal Cancer.

The treatment of metastatic colorectal cancer (mCRC) has improved since the introduction of the epithelial growth factor receptor (EGFR) inhibitors as cetuximab and panitumumab. However, only patients with peculiar genomic profiles benefit from these targeting therapies. In fact, the molecular integrity of RAS genes is a predominant factor conditioning both primary and acquired resistance in non-responders although additional molecular derangements induced by selective anti-EGFR pressure may concur to the failure of those disease treatment, liquid biopsy (LB) appears as a surrogate of tissue biopsy, provides the genomic information to reveal tumor resistance to anti-EGFR agents, the detection of minimal residual disease before adjuvant therapies, and the discovery of tumor molecular status suitable for rechallenging treatments with EGFR antagonists. LB investigates circulating tumor cells (CTCs), cell-free tumor DNA (ctDNA), and tumor-derived exosomes. In mCRC, ctDNA analysis has been demonstrated as a useful method in the mutational tracking of defined genes as well as on tumor burden and detection of molecular alterations driving the resistance to anti-EGFR targeting treatments. However, despite their efficiency in molecular diagnosis and prognostic evaluation of mCRC, the affordability of these procedures is prevalently restricted to research centers, and the lack of consensus validation prevents their translation to clinical practice. Here, we revisit the major mechanisms responsible for resistance to EGFR blockade and review the different methods of LB potentially useful for treatment options in mCRC.

An Italian Retrospective Survey on Bone Metastasis in Melanoma: Impact of Immunotherapy and Radiotherapy on Survival.

BACKGROUND: We performed a multicenter retrospective observational study to investigate the impact of clinical-pathological features and therapeutic strategies on both the complications and survival of patients with bone metastases (BMs) from malignant melanoma. PATIENTS AND METHODS: A total of 305 patients with melanoma and radiological evidence of BMs were retrospectively enrolled from 19 Italian centers. All patients received conventional treatments in accordance with each own treating physician's practice. Both univariate and multivariate models were used to explore the impact of melanoma features, including skeletal-related events (SREs), and different treatments on both overall survival (OS) and time-to-SREs. The chi-squared test evaluated the suitability of several parameters to predict the occurrence of SREs. RESULTS: Eighty-three percent of patients had metachronous BMs. The prevalent (90%) bone metastatic site was the spine, while 45% had involvement of the appendicular skeleton. Forty-seven percent experienced at least one SRE, including palliative radiotherapy (RT) in 37% of cases. No melanoma-associated factor was predictive of the development of SREs, although patients receiving early treatment with bone-targeted agents showed 62% lower risk and delayed time of SRE occurrence. Median OS from the diagnosis of bone metastasis was 10.7 months. The multivariate analysis revealed as independent prognostic factors the number of BMs, number of metastatic organs, baseline lactate dehydrogenase levels, and treatment with targeted therapy or immunotherapy. Subgroup analyses showed the best OS (median = 16.5 months) in the subset of patients receiving both immunotherapy and palliative RT. CONCLUSION: Based on our results, patients undergoing immunotherapy and palliative RT showed an OS benefit suggestive of a possible additive effect. The apparent protective role of bone targeting agent use on SREs observed in our analysis should deserve prospective evaluation.

Large Extracellular Vesicles-A New Frontier of Liquid Biopsy in Oncology.

Extracellular Vesicles (EVs) are emerging as pivotal elements in cancer. Many studies have focused on the role of Small- (S)-EVs but in recent years Large-(L)-EVs have progressively gained increasing interest due to their peculiar content and functions. Tumor-derived L-EVs carry a lot of oncogenic proteins, nucleic acids and lipids to recipient cells and are involved in the reshaping of the tumor microenvironment as well as in the metabolic rewiring and the promotion of the pro-metastatic attitude of cancer cells. Several techniques have been developed for the isolation of L-EVs and commercial kits are also available for efficient and easy recovery of these vesicles. Also, the improvement in DNA sequencing and "omics sciences" profoundly changed the way to analyze and explore the molecular content of L-EVs, thus providing novel and potentially useful cancer biomarkers. Herein, we review the most recent findings concerning the role of L-EVs in cancer and discuss their possible use in oncology as "liquid biopsy" tools as compared to the other classes of EVs.

DEAD-Box Helicase 4 (Ddx4)+ Stem Cells Sustain Tumor Progression in Non-Serous Ovarian Cancers.

DEAD-Box Helicase 4 (Ddx4)+ ovarian stem cells are able to differentiate into several cell types under appropriate stimuli. Ddx4 expression has been correlated with poor prognosis of serous ovarian cancer (OC), while the potential role of Ddx4+ cells in non-serous epithelial OC (NS-EOC) is almost unexplored. The aim of this study was to demonstrate the presence of Ddx4+ cells in NS-EOC and investigate the effect of follicle-stimulating hormone (FSH) on this population. Increased Ddx4 expression was demonstrated in samples from patients with advanced NS-EOC, compared to those with early-stage disease. Under FSH stimulation, OC-derived Ddx4+ cells differentiated into mesenchymal-like (ML) cells, able to deregulate genes involved in cell migration, invasiveness, stemness and chemoresistance in A2780 OC cells. This effect was primarily induced by ML-cells deriving from advanced NS-EOC, suggesting that a tumor-conditioned germ cell niche inhabits its microenvironment and is able to modulate, in a paracrine manner, tumor cell behavior through transcriptome modulation.

Pulmonary enteric adenocarcinoma: an overview.

Most commonly described as sporadic, pulmonary adenocarcinoma with enteric differentiation (PAED) is a rare variant of invasive lung cancer recently established and recognised by the World Health Organization. This tumour is highly heterogeneous and shares several morphological features with pulmonary and colorectal adenocarcinomas. Our objective is to summarise current research on PAED, focusing on its immunohistochemical and molecular features as potential tools for differential diagnosis from colorectal cancer, as well as prognosis definition and therapeutic choice. PAED exhibits an 'entero-like' pathological morphology in more than half cases, expressing at least one of the typical immunohistochemical markers of enteric differentiation, namely CDX2, CK20 or MUC2. For this reason, this malignancy appears often indistinguishable from a colorectal cancer metastasis, making the differential diagnosis laborious. Although standard diagnostic criteria have not been established yet, in the past few years, a number of approaches have been addressed, aimed at defining specific immunohistochemical and molecular signatures. Based on previously published literature, we have collected and analysed molecular and immunohistochemical data on this rare neoplasm, and have described the state of the art on diagnostic criteria as well as major clinical and therapeutic implications.The analysis of data from 295 patients from 58 published articles allowed us to identify the most represented immunohistochemical and molecular markers, as well as major differences between Asian PAEDs and those diagnosed in European/North American countries. The innovative molecular approaches, exploring driver mutations or new gene alterations, could help to identify rare prognostic factors and guide future tailored therapeutic approaches to this rare neoplasm.

Dual-procedural separation of CTCs in cutaneous melanoma provides useful information for both molecular diagnosis and prognosis.

BACKGROUND: Circulating tumor cells (CTCs) have recently emerged as a new dynamic soluble marker for several malignancies including cutaneous melanoma (CM) and are suitable for prognostic evaluations and treatment monitoring. However, to date many limitations still hamper the wide-scale application of CTCs in CM setting, including the lack of standardized methods as well as both low levels and heterogeneity of these cells. METHODS: We developed a protocol for CTC detection in CM based on immune-magnetic sorting to deplete CD45-, CD31- or CD34-positive cells, followed by dielectrophoretic DEPArray separation according to cell morphology and immunophenotype. To this end, we explored the expression of melanoma stem cell antigens (CD271, ABCB5, and RANK) and the epithelial-to-mesenchymal transition markers (N-Cad, -CD44, and -MCAM/CD146) on CTCs from 17 stage IV CM patients, and investigated their BRAF mutational status by droplet digital PCR. RESULTS: The number of CTCs isolated from CM patients ranged from 2 to 91 cells (38 ± 6.4) with respect to healthy donors (p < 0.0002). To confirm the melanoma origin of isolated cells, we observed an 80% agreement between their BRAFV600 mutational status and matched primary tumors. The characterization of the immune phenotype of isolated cells revealed high interindividual and intraindividual heterogeneity that was found to correlate with the clinical outcome. CONCLUSIONS: The dual-step protocol of immune-magnetic sorting and subsequent dielectrophoretic DEPArray separation, turned out to be a suitable method to isolate viable CTCs from stage IV melanoma patients and enabled quantitative and qualitative analyses on these cells, which may deserve prospective evaluation for potential use in the clinical practice.

Extracellular Vesicles and Epigenetic Modifications Are Hallmarks of Melanoma Progression.

Cutaneous melanoma shows a high metastatic potential based on its ability to overcome the immune system's control. The mechanisms activated for these functions vary extremely and are also represented by the production of a number of extracellular vesicles including exosomes. Other vesicles showing a potential role in the melanoma progression include oncosomes and melanosomes and the majority of them mediate tumor processes including angiogenesis, immune regulation, and modifications of the micro-environment. Moreover, a number of epigenetic modifications have been described in melanoma and abundant production of altered microRNAs (mi-RNAs), non-coding RNAs, histones, and abnormal DNA methylation have been associated with different phases of melanoma progression. In addition, exosomes, miRNAs, and other molecular factors have been used as potential biomarkers reflecting disease evolution while others have been suggested to be potential druggable molecules for therapeutic application.

DAXX mutations as potential genomic markers of malignant evolution in small nonfunctioning pancreatic neuroendocrine tumors.

Management of localized well-differentiated pancreatic neuroendocrine tumors (panNETs) is controversial and primarily dependent on tumor size. Upfront surgery is usually recommended for tumors larger than 2 cm in diameter since they frequently show metastatic potential, whereas smaller panNETs are generally characterized by an indolent clinical course, with a rate of relapse or metastasis below 15%. To explore whether increased tumor size is paralleled by genomic variations, we compared the rate and the mutational patterns of putative driver genes that are recurrently altered in these tumors by investigating differential cohorts of panNET surgical specimens smaller (n = 27) or larger than 2 cm (n = 29). We found that the cumulative number of mutations detected in panNETs >2 cm was significantly higher (p = 0.03) relative to smaller tumors, while mutations of DAXX were significantly more frequent in the cohort of larger tumors (p = 0.05). Moreover, mutations of DAXX were associated with features of malignancy including increased grade, nodal involvement and lymphovascular invasion, and independently predicted both relapse after surgery (p = 0.05) and reduced DFS in multivariable analysis (p = 0.02). Our data suggest that alterations of the DAXX/ATRX molecular machinery increase the malignant potential of panNETs, and that identification of mutations of DAXX/ATRX in small, nonfunctioning tumors can predict the malignant progression observed in a minority of them.

Dissection of major cancer gene variants in subsets of circulating tumor cells in advanced breast cancer.

Enumeration of circulating tumor cells (CTCs) may reflect the metastatic potential of breast cancer (BC). By using the DEPArray, we investigated CTCs with respect to their epithelial-to-mesenchymal transition phenotype and compared their genomic heterogeneity with tissue biopsies. Seventeen stage IV BC patients were enrolled. Pre-enriched CTC suspensions were stained with fluorescent-labeled antibodies to epithelial (E) and mesenchymal (M) markers. CTC samples were processed by DEPArray system and clustered in relation to their markers. DNA from CTCs, as well as from primary tumor samples, was sequenced by next generation sequencing to assess the mutational state of 50 major cancer-related genes. We identified four different CTC subsets that harbored different gene variants. The most heterogenous CTC subsets included the M+/E- phenotype, which, however, expressed only 7 repeatedly mutated genes, while in the M-/E+ subset multiple mutations affected only 2 out of 50 genes. When matching all gene variants among CTC subsets, a small number of mutations was shared by only 4 genes, namely ATM, FGFR3, PIK3CA, and TP53 that, however, were absent in primary tumors. Our results postulate that the detected mutations in all CTC subsets may be considered as genomic markers of metastatic dissemination to be investigated during early stages of BC.

Cutaneous metastasis as a primary presentation of a pulmonary enteric adenocarcinoma.

BACKGROUND: Primary pulmonary enteric adenocarcinoma (PEAC) is a rare non-small cell lung cancer subtype sharing morphologic and immunohistochemical features with colorectal adenocarcinoma. Given the frequency of lung metastases in colorectal cancer, the differential diagnosis of PEAC according to routine morphological and immunohistochemical findings may be difficult. Genome sequence by next-generation sequencing has recently introduced new perspectives to better define the diagnosis and tumor sensitivity to treatments, while the rarity of this subtype of cancer still limits the current knowledge of its molecular features and provides no information to address patients to tailored therapies. METHODS: We diagnosed a rare case of subcutaneous metastasis as a first symptom of a PEAC. Formalin-fixed paraffin-embedded samples of the primary tumor and subcutaneous metastases were examined by immunohistochemistry, and subsequently by targeted next-generation sequencing analysis. RESULTS: Morphological and immunohistochemical findings suggested a rare case of metastatic pulmonary adenocarcinoma with enteric aspects. Next-generation sequencing analysis performed on both the primary tumor sample and the cutaneous lesion identified two pathogenic variants on CDKN2A and KRAS in both of them. However, the metastasis showed two additional pathogenic mutations located in SMAD4 and FLT3 genes. CONCLUSIONS: We describe for the first time an extensive molecular analysis on a rare case of PEAC with an unusual cutaneous metastasis. Our observation suggests that a specific pattern of mutations is harbored in this neoplasm, and that additional molecular studies may provide further information to identify prognostic and hopefully predictive genes of response to treatment.

The Role of Cytotoxic Chemotherapy in Well-Differentiated Gastroenteropancreatic and Lung Neuroendocrine Tumors.

OPINION STATEMENT: The treatment landscape of well-differentiated neuroendocrine tumors (NETs) has considerably expanded in recent years, and both somatostatin analogs, radiolabeled somatostatin analogs, everolimus, and sunitinib have been incorporated within the therapeutic armamentarium against these malignancies. Even in the context of multiple treatment options available, cytotoxic chemotherapy plays a pivotal role in the management of pancreatic NETs (panNETs), while its activity in midgut carcinoids and lung NETs is still debated. High response rates, ranging from 30 to 70%, have been consistently reported in studies of panNETs investigating streptozotocin-, temozolomide-, or platinum-based regimens, and an unprecedented prolongation of progression-free survival has been recently demonstrated in a prospective, randomized trial of capecitabine and temozolomide in patients with progressive panNETs. As a general principle, cytotoxic chemotherapy appears particularly appropriate in patients with bulky, symptomatic, or rapidly progressing tumors, especially of pancreatic origin, or in the salvage setting of NET patients who have failed alternative therapeutic options. Emerging evidence has also shown the potential efficacy of induction chemotherapy in patients with locally advanced or oligometastatic panNET, but prospective validation is needed before implementation of this approach in routine clinical practice. At present, there is no consensus on adjuvant therapy in pulmonary NETs, and differences between guideline recommendations at this regard mainly stem from the lack of high-level evidence. In the future, the identification of molecular biomarkers of response to chemotherapy might allow better patient preselection, thus leading to improved outcomes.

Rare Dihydropyrimidine Dehydrogenase Variants and Toxicity by Floropyrimidines: A Case Report.

Variations in the activity, up to absolute deficiency, of the enzyme dihydropyrimidine dehydrogenase (DPD), result in the occurrence of adverse reactions to chemotherapy, and have been included among the pharmacogenetic factors underlying inter-individual variability in response to fluoropyrimidines. The study of single-nucleotide polymorphisms of the DPYD gene, which encodes the DPD enzyme, is one of the main parameters capable of predicting reduced enzymatic activity and the consequent influence on fluoropyrimidine treatment, in terms of reduction of both adverse reactions and therapeutic efficacy in disease control. In this paper, we describe a patient with metastatic breast cancer showing signs of increased toxicity following capecitabine therapy. The DPD enzyme activity analysis revealed a partial deficiency. The study of the most frequent polymorphisms of the DPYD gene suggested a wild-type genotype but indicated a novel variant c.1903A>G (p.Asn635Asp), not previously described, proximal to the splice donor site of exon 14. After excluding the potential pathogenic feature of the newly-identified variant, we performed cDNA sequencing of the entire DPYD coding sequence. This analysis identified the variants c.85T>C and c.496A>G, which were previously described as pivotal components of the haplotype associated with decreased enzyme activity and suggested that both variant alleles are related to DPD deficiency. The clinical case findings described in this study emphasize the importance of performing complete genetic analysis of the DPYD gene in order to identify rare and low frequency variants potentially responsible for toxic reactions to fluoropyrimidine treatment.

The Tumor Microenvironment in Neuroendocrine Tumors: Biology and Therapeutic Implications.

Neuroendocrine tumors (NETs) include a heterogeneous group of malignancies arising in the diffuse neuroendocrine system and characterized by indolent growth. Complex interactions take place among the cellular components of the microenvironment of these tumors, and the recognition of the molecular mediators of their interplay and cross talk is crucial to discover novel therapeutic targets. NET cells overexpress a plethora of proangiogenic molecules including vascular endothelial growth factor, platelet-derived growth factor, fibroblast growth factor, semaphorins, and angiopoietins that promote both recruitment and proliferation of endothelial cell precursors, thus resulting among the most vascularized cancers with a microvessel density 10-fold higher than epithelial tumors. Also, NETs operate multifaceted interactions with stromal cells, both at local and distant sites, and whether their paracrine secretion of serotonin, connective tissue growth factor, and transforming growth factor ß primarily drives the fibroblast activation to enhance the tumor proliferation, on the other side NET-derived profibrotic factors accelerate the extracellular matrix remodeling and contribute to heart valves and/or mesenteric fibrosis development, namely, major complications of functioning NETs. However, at present, little is known on the immune landscape of NETs, but accumulating evidence shows that tumor-infiltrating neutrophils, mast cells, and/or macrophages concur to promote the neoangiogenic switch of these tumors by either direct or indirect mechanisms. On the other hand, immune checkpoint molecules are heterogeneously expressed in NETs' surrounding cells, and it is unclear whether or not tumor-infiltrating lymphocytes are antitumor armed within the microenvironment, given their low mutational load. Here, we review the current knowledge on both gastroenteropancreatic and pulmonary NETs' microenvironment as well as both established and innovative treatments aimed at targeting the tumor-host interplay.

Circulating tumour cells and their association with bone metastases in patients with neuroendocrine tumours.

BACKGROUND: Bone metastases are associated with a worse outcome in patients with neuroendocrine tumours (NETs). Tumour overexpression of C-X-C chemokine receptor 4 (CXCR4) appears predictive of skeletal involvement. We investigated the role of circulating tumour cells (CTCs) and CXCR4 expression on CTCs as potential predictors of skeleton invasion. METHODS: Blood from patients with metastatic bronchial, midgut or pancreatic NET (pNET) was analysed by CellSearch. CXCR4 immunohistochemistry was performed on matched formalin-fixed paraffin-embedded (FFPE) samples. RESULTS: Two hundred and fifty-four patients were recruited with 121 midgut and 119 pNETs, of which 51 and 36% had detectable CTCs, respectively. Bone metastases were reported in 30% of midgut and 23% of pNET patients and were significantly associated with CTC presence (p = 0.003 and p < 0.0001). In a subgroup of 40 patients, 85% patients with CTCs had CTCs positive for CXCR4 expression. The proportion of CXCR4-positive CTCs in patients with bone metastases was 56% compared to 35% in those without (p = 0.18) it. Staining for CXCR4 on matched FFPE tissue showed a trend towards a correlation with CXCR4 expression on CTCs (p = 0.08). CONCLUSIONS: CTC presence is associated with bone metastases in NETs. CXCR4 may be involved in CTC osteotropism and present a therapeutic target to reduce skeletal morbidity.

25 Hydroxyvitamin D Levels are Negatively and Independently Associated with Fat Mass in a Cohort of Healthy Overweight and Obese Subjects.

BACKGROUND: Obesity is associated with lower serum vitamin D (25(OH)D) levels through several mechanisms. The aim of the study was to examine the possibility of a negative association between fat mass and 25(OH)D levels in a cohort of otherwise healthy overweight and obese subjects, independently of age, sex, blood pressure levels and anthropometric and metabolic parameters. MATERIALS AND METHODS: 147 overweight and obese subjects (106 women and 41 men), aged between 18 and 69 years, were enrolled into the study. All of them did not show any clinically evident metabolic or chronic diseases (i.e. hypertension, diabetes mellitus, renal failure, etc.) and did not use any kind of drug. Serum fasting levels of 25(OH)D, insulin, glucose, uric acid and lipids (triglycerides, total, HDL and LDL cholesterol) were measured. The season in which the blood samples were collected was autumn. Insulin resistance was assessed by using the Homeostasis Model Assessment (HOMA-IR). Body composition parameters (Fat Mass [FM], Fat Free Mass [FFM], body cell mass [BCM], Total Body Water [TBW]) were measured by electrical Bioimpedance Analysis (BIA). Lastly, demographic, anthropometric and clinical parameters (age, Body Mass Index [BMI], Waist Circumference [WC], Systolic (SBP) and Diastolic (DBP) blood pressure) were also assessed. RESULTS: 25(OH)D levels were significantly and negatively correlated with BMI (P <0.001), WC (P <0.01), DBP (P <0.05), insulin (P <0.001), HOMA-IR (P <0.01), triglycerides (P <0.01), and fat mass (P <0.001). A multivariate regression analysis was performed by considering 25(OH)D levels as the dependent variable and sex, waist circumference, fat mass, DBP, triglycerides, and insulin (or HOMAIR) as the independent ones, and 25(OH)D levels maintained a significant and independent relationship only with fat mass (negative) (P <0.01). CONCLUSION: This study clearly shows that 25(OH)D circulating levels are progressively lower with the increase of fat mass, independently of sex, body fat distribution, blood pressure and insulin and metabolic parameters. These data strongly show that adipose tissue accumulation per se is absolutely the main factor responsible factor for lower 25(OH)D levels in obese subjects, possibly through sequestration of fat soluble 25(OH)D in fat mass.