Angiogenesis and vascular maturation in neuroendocrine tumors

A new endoscopic tumor grading for rectal neuroendocrine tumors: Correlation of vascular pattern with histopathology

INTRODUCTION

The clinical utility of applying endoscopic vascular patterns in rectal neuroendocrine tumor (NET) remains unknown. The aims of this study were to develop a system for utilizing vascular patterns for tumor grade and submucosal invasion depth.

METHODS

We retrospectively included patients diagnosed as well-differentiated rectal NET between March 2015 and February 2024. The entire dataset was divided into evaluation and validation sets. In the evaluation set, the relationship between endoscopic tumor features and tumor grade was explored using a multivariable regression model. Based on the endoscopic vessel characteristics, vascular patterns were established and classified into V1 and V2 types. In the validation set, 104 lesions were used to assess the diagnostic performance of the vascular patterns.

RESULTS

Multivariate analysis demonstrated good association between tumor grade and vascular pattern (13.65 odds ratio; 95 % confidence interval, 2.06-90.58). Vascular patterns exhibited almost perfect inter- and intra-observer agreement (kappa = 0.957). The sensitivity, positive predictive value and accuracy of V1 for predicting grade 1 were 94.5 %, 97.7 and 93.3 %, respectively. Histopathological analysis revealed significantly deeper submucosal invasion depth for V2 than that for V1 lesions (p < 0.001).

CONCLUSIONS

Vascular patterns can help identify tumor grade and assess submucosal invasion depth.

Histopathological analysis of tumor microenvironment in adrenocortical carcinoma: Possible effects of in situ disorganized glucocorticoid production on tumor immunity

Adrenocortical carcinoma (ACC) patients with glucocorticoid excess have been reported to be associated with decreased tumor-infiltrating immune cells, but the effects of in situ glucocorticoid production on tumor immunity have remained unknown. In addition, ACC was also known to harbor marked intra-tumoral heterogeneity of steroidogenesis or disorganized steroidogenesis. Therefore, in this study, we immune-profiled tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs) and pivotal steroidogenic enzymes of glucocorticoid biosynthesis (CYP17A and CYP11B1) to explore the potential effects of in situ glucocorticoid production and intra-tumoral heterogeneity/disorganized steroidogenesis on tumor immunity of ACC. We also studied the correlations of the status of tumor immunity with that of angiogenesis and tumor grade to further explore the tumor tissue microenvironment of ACC. TILs (CD3, CD4, CD8, and FOXP3), TAMs (CD68 and CD163), key steroidogenic enzymes of glucocorticoid (CYP17A and CYP11B1), angiogenesis (CD31 and vasohibin-1 (VASH-1)), tumor grade (Ki-67 and Weiss score) were immunohistochemically evaluated in 34 ACCs. Increased CYP17A immunoreactivity in the whole tumor area was significantly positively correlated with FOXP3-positive TILs (p = 0.021) and negatively with CD4/CD3 ratio (p = 0.001). Increased CYP11B1 immunoreactivity in the whole tumor area was significantly positively correlated with CD8/CD3 (p = 0.039) and CD163/CD68 ratios (p = 0.006) and negatively with CD4-positive TILs (p = 0.036) and CD4/CD3 ratio (p = 0.001). There were also significant positive correlations between CYP17A and CD8 (r = 0.334, p < 0.001) and FOXP3-positive TILs (r = 0.414, p < 0.001), CD8/CD3 ratio (r = 0.421, p < 0.001), and CD68-positive TAMs (r = 0.298, p < 0.001) in randomly selected areas. Significant positive correlations were also detected between CYP11B1 and CD8/CD3 ratio (r = 0.276, p = 0.001) and negative ones detected between CYP11B1 and CD3- (r = -0.259, p = 0.002) and CD4-positive TILs (r = -0.312, p < 0.001) in those areas above. Increased micro-vessel density (MVD) -VASH-1 was significantly positively correlated with CD68- (p = 0.015) and CD163-positive TAMs (p = 0.009) and CD163/CD68 ratio and the high VASH-1 with CD163-positive TAMs (p = 0.042). Ki-67 labeling index was significantly positively correlated with MAD-VASH-1 (p = 0.006) and VASH-1 (p = 0.006) status. Results of our present study indicated that in situ glucocorticoid production did influence the status of tumor immunity in ACC. In particular, increased levels of CYP17A and CYP11B1, both involved in glucocorticoid producing immunoreactivity played different effects on tumor immunity, i.e., reflecting the involvement of intra-tumoral heterogeneity and disorganized steroidogenesis of ACC, which also did indicate the importance of in situ approaches when analyzing tumor immunity of ACC.

A novel GRK3-HDAC2 regulatory pathway is a key direct link between neuroendocrine differentiation and angiogenesis in prostate cancer progression

The mechanisms underlying the progression of prostate cancer (PCa) to neuroendocrine prostate cancer (NEPC), an aggressive PCa variant, are largely unclear. Two prominent NEPC phenotypes are elevated NE marker expression and heightened angiogenesis. Identifying the still elusive direct molecular links connecting angiogenesis and neuroendocrine differentiation (NED) is crucial for our understanding and targeting of NEPC. Here we found that histone deacetylase 2 (HDAC2), whose role in NEPC has not been reported, is one of the most upregulated epigenetic regulators in NEPC. HDAC2 promotes both NED and angiogenesis. G protein-coupled receptor kinase 3 (GRK3), also upregulated in NEPC, is a critical promoter for both phenotypes too. Of note, GRK3 phosphorylates HDAC2 at S394, which enhances HDAC2's epigenetic repression of potent anti-angiogenic factor Thrombospondin 1 (TSP1) and master NE-repressor RE1 Silencing Transcription Factor (REST). Intriguingly, REST suppresses angiogenesis while TSP1 suppresses NE marker expression in PCa cells, indicative of their novel functions and their synergy in cross-repressing the two phenotypes. Furthermore, the GRK3-HDAC2 pathway is activated by androgen deprivation therapy and hypoxia, both known to promote NED and angiogenesis in PCa. These results indicate that NED and angiogenesis converge on GRK3-enhanced HDAC2 suppression of REST and TSP1, which constitutes a key missing link between two prominent phenotypes of NEPC.

Pilot Study: FSHR Expression in Neuroendocrine Tumors of the Appendix

Appendix neuroendocrine neoplasm (ANEN) treatment is based on tumor size and proliferation markers. Recently, the role of the follicle-stimulating hormone receptor (FSHR) from the clinical perspective has also been increasingly discussed. The FSHR is expressed in the endothelial cells of both intratumoral and peritumoral blood vessels, where it contributes to neoangiogenesis and blood vessel remodeling. FSHR expression is associated with a range of tumor types, such as gastrointestinal tumors, and it is not detected in healthy tissues located more than 10 mm from the tumor site or in tumor lymphatics. In this study, we evaluated the expression of FSHR and CD31 in the blood vessels of ANENs in females and males with confirmed histopathology. We conducted a quantitative analysis of the immunohistochemical reactions and found a higher number of microvessels in the mucosa and submucosa of neuroendocrine tumors in the appendix. A higher level of FSHR expression was observed in women. Future research should consider whether an elevated number of blood vessels along with a strong pattern of FSHR expression may influence future treatment strategies.

Efficacy and toxicity of surufatinib in neuroendocrine tumors: A systematic review and meta-analysis

The incidence and prevalence of neuroendocrine neoplasms (NENs) has increased in the US in recent decades. These are well-vascularized tumors, but no antiangiogenic drug has been approved for treatment of extra-pancreatic NENs. The aim is to assess efficacy and safety of surufatinib in pancreatic and extra-pancreatic NETs. We searched PubMed, Embase, Cochrane Library, Web of Science and Clinicaltrials.gov. Clinical trials and observational studies that provided safety and efficacy data in clinical terms were included. Characteristics of the study, baseline characteristics of participants, treatment drugs, measures of efficacy, and toxicity (≥grade 3 adverse effects) were extracted. The meta-analysis was performed using the "R" programming language. Risk ratio (RR) of objective response (OR)/partial response (PR) was 8.55 (95% CI: 1.68-43.66, I2  = 0) in favor of surufatinib. The hazard ratio (HR) of progression-free survival (PFS) was 0.48 (95% CI: 0.25-0.92, I2  = 77%) in favor of surufatinib. The risk of ≥grade 3 adverse effects: diarrhea, hypertension, hypertriglyceridemia, proteinuria, and vomiting were high with the use of surufatinib. Quality of life (QoL) was similar in surufatinib and placebo groups except for the diarrhea that was high with surufatinib. Lack of randomized clinical trials in non-Chinese population. Surufatinib is well tolerated and is more effective than placebo in both pancreatic and extra-pancreatic NETs. More multicenter randomized, double-blinded clinical trials are needed to confirm these results.

Assessment of the Concentration of Endogenous Factors Regulating Angiogenesis, VASH-1 and VEGF-A, in the Blood Serum of Patients with Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) constitute about 2% of all malignant neoplasms, and the angiogenesis process in these tumors is still of a great interest. Vasohibin-1 (VASH-1) is an angiogenesis inhibitor, while vascular endothelial growth factor A (VEGF-A) is one of the main factors promoting vascular formation. The subject of this study was to assess serum concentration of these factors in patients with diagnosed NEN and in control group. Methods. The study group consisted of 120 patients with diagnosed NENs, while the control group consisted of 69 healthy volunteers. The concentrations of VASH-1 and VEGF-A in serum were tested using the ELISA. We also analyzed the association of the concentration of these factors with demographic data (e.g., age and gender), body mass index (BMI), primary tumor location, histological grade, metastasis, clinical staging, selected biochemical parameters and markers of NENs, and information on smoking habits. Results. The mean concentration of VASH-1 was 218.8 ± 359.8 pg/ml in the study group and 973.1 ± 1239.4 pg/ml in the control group, that difference was statistically significant (p < 0.05). In the NEN group, the highest concentration of VASH-1 was in patients with pancreatic NENs in relation to NENs with different location of the primary tumor (p < 0.05). Negative correlation was found between the concentration of VASH-1 and serotonin (r_S = −0.19, p < 0.05). No statistically significant differences were observed for VEGF-A (p = 0.658). Conclusions. Patients with NENs showed lower serum level of VASH-1 in comparison to healthy volunteers. The highest level of VASH-1 was observed in tumors localized in pancreas. This might reflect the relevant function of VASH-1 in NENs and requires further evaluation to further knowledge of angiogenesis in NENs. Furthermore, the serum concentration of VEGF-A showed no statistical differences and probably does not have diagnostic value in this group of patients.

Beta-adrenergic signaling on neuroendocrine differentiation, angiogenesis, and metastasis in prostate cancer progression

Prostate cancer is a complex, heterogeneous disease that mainly affects the older male population with a high-mortality rate. The mechanisms underlying prostate cancer progression are still incompletely understood. Beta-adrenergic signaling has been shown to regulate multiple cellular processes as a mediator of chronic stress. Recently, beta-adrenergic signaling has been reported to affect the development of aggressive prostate cancer by regulating neuroendocrine differentiation, angiogenesis, and metastasis. Here, we briefly summarize and discuss recent advances in these areas and their implications in prostate cancer therapeutics. We aim to provide a better understanding of the contribution of beta-adrenergic signaling to the progression of aggressive prostate cancer.

Optimized functional and structural design of dual-target LMRAP, a bifunctional fusion protein with a 25-amino-acid antitumor peptide and GnRH Fc fragment

To develop fusion protein of a GnRH Fc fragment and the integrin targeting AP25 antitumor peptide for GnRH receptor-expressing cancer therapy. The LMRAP fusion protein was constructed. A transwell invasion assay was performed. The gene mRNA and protein levels of GnRHR-I, α5β1, and αvβ3 in different cancer cell lines were assessed. Cell proliferation was measured using a cell counting kit-8. An antagonist assay was performed on GnRH receptors. Anti-tumor activity was evaluated with a mouse xenograft tumor model. Immunohistochemistry (IHC) was applied to detect CD31 and CD34 expressions. Pharmacokinetic characteristics were determined with an indirect competition ELISA. The developed bifunctional fusion protein LMRAP not only inhibited HUVEC invasion, but also inhibited proliferation of GnRHR-I, α5β1, and αvβ3 high expression cancer cells. The IC₅₀ for LMRAP in the GnRH receptor was 6.235 × 10⁻⁴ mol/L. LMRAP significantly inhibited human prostate cancer cell line 22RV1 proliferation in vivo and in vitro. LMRAP significantly inhibited CD31 and CD34 expressions. The elimination half-life of the fusion protein LMRAP was 33 h in rats. The fusion protein made of a GnRH Fc fragment and the integrin targeting AP25 peptide retained the bifunctional biological activity of GnRHR blocking, angiogenesis inhibition, prolonged half-life and good tolerance.

Molecular Links Between Angiogenesis and Neuroendocrine Phenotypes in Prostate Cancer Progression

As a common therapy for prostate cancer, androgen deprivation therapy (ADT) is effective for the majority of patients. However, prolonged ADT promotes drug resistance and progression to an aggressive variant with reduced androgen receptor signaling, so called neuroendocrine prostate cancer (NEPC). Until present, NEPC is still poorly understood, and lethal with no effective treatments. Elevated expression of neuroendocrine related markers and increased angiogenesis are two prominent phenotypes of NEPC, and both of them are positively associated with cancers progression. However, direct molecular links between the two phenotypes in NEPC and their mechanisms remain largely unclear. Their elucidation should substantially expand our knowledge in NEPC. This knowledge, in turn, would facilitate the development of effective NEPC treatments. We recently showed that a single critical pathway regulates both ADT-enhanced angiogenesis and elevated expression of neuroendocrine markers. This pathway consists of CREB1, EZH2, and TSP1. Here, we seek new insights to identify molecules common to pathways promoting angiogenesis and neuroendocrine phenotypes in prostate cancer. To this end, our focus is to summarize the literature on proteins reported to regulate both neuroendocrine marker expression and angiogenesis as potential molecular links. These proteins, often described in separate biological contexts or diseases, include AURKA and AURKB, CHGA, CREB1, EZH2, FOXA2, GRK3, HIF1, IL-6, MYCN, ONECUT2, p53, RET, and RB1. We also present the current efforts in prostate cancer or other diseases to target some of these proteins, which warrants testing for NEPC, given the urgent unmet need in treating this aggressive variant of prostate cancer.

Histopathological Analysis of Tumor Microenvironment and Angiogenesis in Pheochromocytoma

Pheochromocytomas (PHEOs) are relatively rare catecholamine-producing tumors derived from adrenal medulla. Tumor microenvironment (TME) including neoangiogenesis has been explored in many human neoplasms but not necessarily in PHEOs. Therefore, in this study, we examined tumor infiltrating lymphocytes (CD4 and CD8), tumor associated macrophages (CD68 and CD163), sustentacular cells (S100p), and angiogenic markers (CD31 and areas of intratumoral hemorrhage) in 39 cases of PHEOs in the quantitative fashion. We then compared the results with pheochromocytoma of the adrenal gland scaled score (PASS), grading system for pheochromocytoma and paraganglioma (GAPP) and the status of intra-tumoral catecholamine-synthesizing enzymes (TH, DDC, and PNMT) as well as their clinicopathological factors. Intratumoral CD8 (p = 0.0256), CD31 (p = 0.0400), and PNMT (p = 0.0498) status was significantly higher in PHEOs with PASS <4 than PASS ≧4. In addition, intratumoral CD8⁺ lymphocytes were also significantly more abundant in well-than moderately differentiated PHEO according to GAPP score (p = 0.0108) and inversely correlated with tumor size (p = 0.0257). Intratumoral CD68⁺ cells were significantly higher in PHEOs with regular or normal histological patterns than those not (p = 0.0370) and inversely correlated with tumor size (p = 0.0457). The status of CD163 was significantly positively correlated with that of CD8 positive cells (p = 0.0032). The proportion of intratumoral hemorrhage areas was significantly higher in PHEOs with PASS ≧4 (p = 0.0172). DDC immunoreactivity in tumor cells was significantly positively correlated with PASS score (p = 0.0356) and TH status was significantly higher in PHEOs harboring normal histological patterns (p = 0.0236) and cellular monotony (p = 0.0219) than those not. Results of our present study did demonstrate that abundant CD8⁺ and CD68⁺ cells could represent a histologically low-scored tumor. In particular, PHEOs with increased intratumoral hemorrhage should be considered rather malignant. In addition, abnormal catecholamine-producing status of tumor cells such as deficient PNMT and TH and increased DDC could also represent more aggressive PHEOs.

Heterogeneity of Vascular Endothelial Cells, De Novo Arteriogenesis and Therapeutic Implications in Pancreatic Neuroendocrine Tumors

Arteriogenesis supplies oxygen and nutrients in the tumor microenvironment (TME), which may play an important role in tumor growth and metastasis. Pancreatic neuroendocrine tumors (pNETs) are the second most common pancreatic malignancy and are frequently metastatic on presentation. Nearly a third of pNETs secrete bioactive substances causing debilitating symptoms. Current treatment options for metastatic pNETs are limited. Importantly, these tumors are highly vascularized and heterogeneous neoplasms, in which the heterogeneity of vascular endothelial cells (ECs) and de novo arteriogenesis may be critical for their progression. Current anti-angiogenetic targeted treatments have not shown substantial clinical benefits, and they are poorly tolerated. This review article describes EC heterogeneity and heterogeneous tumor-associated ECs (TAECs) in the TME and emphasizes the concept of de novo arteriogenesis in the TME. The authors also emphasize the challenges of current antiangiogenic therapy in pNETs and discuss the potential of tumor arteriogenesis as a novel therapeutic target. Finally, the authors prospect the clinical potential of targeting the FoxO1-CD36-Notch pathway that is associated with both pNET progression and arteriogenesis and provide insights into the clinical implications of targeting plasticity of cancer stem cells (CSCs) and vascular niche, particularly the arteriolar niche within the TME in pNETs, which will also provide insights into other types of cancer, including breast cancer, lung cancer, and malignant melanoma.

Lymphovascular invasion as a prognostic value in small rectal neuroendocrine tumor treated by local excision: A systematic review and meta-analysis

Because rectal neuroendocrine tumors (NETs) are usually small-sized despite of malignant potential, endoscopic resection techniques are recommended. It is unclear whether the lymphovascular invasion (LVI) in the endoscopic resected specimens of small rectal NETs should be indicated for completion surgery. We performed a systematic review and meta-analysis for the incidence of LVI in small rectal NETs (≤20 mm) treated by endoscopic resection and its prognostic impacts. We searched the relevant literature published before January 2019. A total of 21 publications including 1816 patients were enrolled. Overall prevalence of LVI in small rectal NETs was 21.8%. Immunohistochemical method significantly increased the detection rate of LVI up to 35.8% compared than H&E staining only (13.2%). Tumor size more than 5 mm was a risk factor for LVI in small rectal NET, whereas tumor grade did not influence the risk. The LVI in the endoscopic resected specimens was a risk factor for subsequent lymph node metastasis. Separately analyzed in detail, the vascular invasion had a stronger impact on lymph node metastasis than the lymphatic invasion. The prognosis of endoscopically treated rectal NET with LVI was excellent with only 0.3% of recurrence rate during the 5-year follow-up period. LVI is highly prevalent and a risk factor for lymph node metastasis in the small rectal NETs. Endoscopically treated small rectal NETs had excellent short-term prognoses despite of LVI. Immediate completion radical surgery is not absolutely necessary for the LVI-positive small rectal NETs. However, long-term follow-up is recommended for any delayed recurrence.

Strong Antitumor Activity of Bevacizumab and Aflibercept in Neuroendocrine Carcinomas: In-Depth Preclinical Study

BACKGROUND

Neuroendocrine carcinoma (NEC) is a rare and very aggressive tumor. It has been greatly understudied, and very little is known about optimal treatment strategy for patients with this disease. The purpose of this study was to evaluate in vivo whether anti-vascular endothelial growth factor (VEGF) drugs could be a therapeutic alternative for these tumors with a poor prognosis.

METHODS

We have developed 2 xenograft models using either human cell line derived from lung (H460) or from colon (COLO320) NEC to assess the effect of 2 antiangiogenic drugs, aflibercept and bevacizumab, on tumor growth and their pathological characteristics. Additionally, tumors were subjected to immunohistochemistry staining and proteins were measured with Western blot and ELISA.

RESULTS

Both aflibercept and bevacizumab showed significant antitumor activity (p < 0.001). In the H460 model, aflibercept resulted in 94% tumor growth inhibition (TGI) and bevacizumab treatment resulted in 72.2% TGI. Similarly, in the COLO320 model, aflibercept and bevacizumab resulted in 89.3 and 84% TGI, respectively. Moreover, antitumor activity occurs early after treatment initiation. Using Tumor Control Index score, which address the kinetics of tumor growth in a way comparable to the methods used in human clinical studies, we confirmed that both drugs inhibit significantly tumor growth. When tumor stabilization was evaluated, aflibercept shows higher ability to stabilize NEC tumors than bevacizumab.

CONCLUSION

Results derived from this study strongly support anti-VEGF therapies, especially aflibercept, as a novel therapeutic option in NECs. Further studies are necessary, but our observations encourage the evaluation of antiangiogenics in clinical trials combined with standard chemotherapy.

Role of the tumor microenvironment in digestive neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) represent a group of heterogeneous tumors whose incidence increased over the past few years. Around half of patients already present with metastatic disease at the initial diagnosis. Despite extensive efforts, cytotoxic and targeted therapies have provided only limited efficacy for patients with metastatic GEP-NETs, mainly due to the development of a certain state of resistance. One factor contributing to both the failure of systemic therapies and the emergence of an aggressive tumor phenotype may be the tumor microenvironment (TME), comprising dynamic and adaptative assortment of extracellular matrix components and non-neoplastic cells, which surround the tumor niche. Accumulating evidence shows that the TME can simultaneously support both tumor growth and metastasis and contribute to a certain state of resistance to treatment. In this review, we summarize the current knowledge of the TME of GEP-NETs and discuss the current therapeutic agents that target GEP-NETs and those that could be of interest in the (near) future.

Androgen deprivation promotes neuroendocrine differentiation and angiogenesis through CREB-EZH2-TSP1 pathway in prostate cancers

The incidence of aggressive neuroendocrine prostate cancers (NEPC) related to androgen-deprivation therapy (ADT) is rising. NEPC is still poorly understood, such as its neuroendocrine differentiation (NED) and angiogenic phenotypes. Here we reveal that NED and angiogenesis are molecularly connected through EZH2 (enhancer of zeste homolog 2). NED and angiogenesis are both regulated by ADT-activated CREB (cAMP response element-binding protein) that in turn enhances EZH2 activity. We also uncover anti-angiogenic factor TSP1 (thrombospondin-1, THBS1) as a direct target of EZH2 epigenetic repression. TSP1 is downregulated in advanced prostate cancer patient samples and negatively correlates with NE markers and EZH2. Furthermore, castration activates the CREB/EZH2 axis, concordantly affecting TSP1, angiogenesis and NE phenotypes in tumor xenografts. Notably, repressing CREB inhibits the CREB/EZH2 axis, tumor growth, NED, and angiogenesis in vivo. Taken together, we elucidate a new critical pathway, consisting of CREB/EZH2/TSP1, underlying ADT-enhanced NED and angiogenesis during prostate cancer progression.

New insights into hypoxia-related mechanisms involved in different microvascular patterns of bronchopulmonary carcinoids and poorly differentiated neuroendocrine carcinomas. Role of ribonuclease T2 (RNASET2) and HIF-1α

Ribonuclease T2 (RNASET2) is a pleiotropic and polyfunctional protein, which exerts several different activities in neoplastic cells since the early steps of tumor development. Besides having an antitumorigenic activity, RNASET2 inhibits both bFGF-induced and VEGF-induced angiogenesis and has a role as a stress-response, alarmin-like, protein. In this study, we investigated RNASET2 expression in well-differentiated and poorly differentiated neuroendocrine neoplasms of the lung (Lu-NENs), which are known to show clear-cut differences in morphology, biology and clinical behavior. In addition, we explored possible relationships between RNASET2 expression and a series of immunohistochemical markers related to hypoxic stress, apoptosis, proliferation and angiogenesis. Our results showed a significantly higher expression of RNASET2, HIF-1α, and its target CA IX in poorly differentiated than in well-differentiated Lu-NENs, the former also showing higher proliferation and apoptotic rates, as well as a lower microvessel density (MVD) than the latter. Moreover, we were able to demonstrate in vitro an overexpression of RNASET2 in consequence of the activation of HIF-1α. In conclusion, we suggest that in poorly differentiated Lu-NENs, RNASET2 expression may be induced by HIF-1α, behaving as an alarmin-like molecule. In this aggressive group of cancers, which have highly deregulated proliferation pathways, RNASET2 fails to exert the growth-inhibiting effects described in other types of neoplasms. Its increased expression, however, may contribute to the typical phenotypic alterations seen in poorly differentiated Lu-NENs, such as the high apoptotic rate and the extensive necrosis, and may also enhance the low MVD observed in these neoplasms.

Progesterone arrested cell cycle progression through progesterone receptor isoform A in pancreatic neuroendocrine neoplasm

In pancreatic neuroendocrine neoplasms (Pan-NEN) progesterone signaling has been shown to have both inhibitory and stimulatory effects on cell proliferation. The ability of progesterone to inhibit tumor proliferation is of particular interest and is suggested to be mediated through the less abundantly expressed progesterone receptor (PR) isoform A (PRA). To date the mechanistic processes underlying this inhibition of proliferation remain unclear. To examine the mechanism of PRA actions, the human Pan-NEN cell line QGP-1, that endogenously expresses PR isoform B (PRB) without PRA, was transfected with PRA. PRA transfection suppressed the majority of cell cycle related genes increased by progesterone including cyclin A2 (CCNA2), cyclin B1 (CCNB1), cyclin-dependent kinase 1 (CDK1) and cyclin-dependent kinase 2 (CDK2). Importantly, following progesterone administration cell cycle distribution was shifted to S and G2/M phases in the naïve cell line but in PRA-transfected cells, this effect was suppressed. To see if these mechanistic insights were confirmed in patient samples PRA, PRB, CCNA2, CCNB, CDK1 and CDK2 immunoreactivities were assessed in Pan-NEN cases. Higher levels of cell cycle markers were associated with higher WHO grade tumors and correlations between the markers suggested formation of cyclin/CDK activated complexes in S and G2/M phases. PRA expression was associated with inverse correlation of all cell cycle markers. Collectively, these results indicate that progesterone signals through PRA negatively regulates cell cycle progression through suppressing S and G2/M phases and downregulation of cell cycle phases specific cyclins/CDKs.

Neuroendocrine Carcinoma of the Stomach: A Response to Combination Chemotherapy Consisting of Ramucirumab Plus Paclitaxel

Extrapulmonary neuroendocrine carcinoma (NEC) is a rare disease, and there is no standard chemotherapy. A 73-year-old man was diagnosed with advanced gastric NEC. He received chemotherapy of irinotecan plus cisplatin, and amrubicin monotherapy. After failure of second-line chemotherapy, he received ramucirumab plus paclitaxel; this treatment was chosen because vascular endothelial growth factor 2 was strongly expressed in the tumor endothelial cells. After two cycles, his NEC had markedly reduced in size, and he continued with this treatment for over eight months. In this case, the combination of an anti-angiogenic inhibitor and a cytotoxic agent was highly effective for gastric NEC.

Combining 2D angiogenesis and 3D osteosarcoma microtissues to improve vascularization

Angiogenesis is now well known for being involved in tumor progression, aggressiveness, emergence of metastases, and also resistance to cancer therapies. In this study, to better mimic tumor angiogenesis encountered in vivo, we used 3D culture of osteosarcoma cells (MG-63) that we deposited on 2D endothelial cells (HUVEC) grown in monolayer. We report that endothelial cells combined with tumor cells were able to form a well-organized network, and that tubule-like structures corresponding to new vessels infiltrate tumor spheroids. These vessels presented a lumen and expressed specific markers as CD31 and collagen IV. The combination of 2D endothelial cells and 3D microtissues of tumor cells also increased expression of angiogenic factors as VEGF, CXCR4 and ICAM1. The cell environment is the key point to develop tumor vascularization in vitro and to be closer to tumor encountered in vivo.

B-mode and contrast-enhancement characteristics of small nonincidental neuroendocrine pancreatic tumors

BACKGROUND AND OBJECTIVES

Imaging of the pancreas for detection of neuroendocrine tumors is indicated as surveillance in multiple endocrine neoplasia type 1 (MEN1) or if typical clinical symptoms combined with hormone production raise the suspicion of a neuroendocrine tumor. Endoscopic ultrasound (EUS) is considered the best imaging modality to detect small pancreatic tumors. However, little is known about how small pancreatic neuroendocrine tumors (pNETs) present on EUS.

PATIENTS AND METHODS

In this multicenter study, we retrospectively analyzed the endosonographic characteristics of small pNETs which had been detected due to typical biochemistry and clinical symptoms or during surveillance of MEN 1. Only small pancreatic tumors ≤15 mm with histological confirmation as pNET were included. B-mode and contrast-enhanced ultrasound- and EUS patterns were analyzed.

RESULTS

Among 32 patients with histologically proven small pNETs, 7 patients had known MEN1. Among the pNETs, 20 were insulinoma, 2 gastrinoma, 3 glucagonoma, 6 nonfunctional in MEN1, and one PPoma. 94% of the pNET appeared hypoechogenic, only 1 isoechogenic and 1 hyperechogenic. After contrast injection, 90% of the pNETS showed hyperenhancement compared to the surrounding pancreatic parenchyma.

CONCLUSION

The high spatial resolution of EUS allows detection and even cytological confirmation of pNET <7 mm diameter. Hypoechogenicity in B-mode and hyperenhancement after injection of contrast agents are endosonographic characteristics of small pNET and present in >90% of pNETs.

Esophageal anastomosis - how the granulation phase of wound healing improves the incidence of anastomotic leakage

A two-stage esophagectomy with an interval for reconstruction of the esophagus creates an opportunity for the esophageal stump to recover from vessel injury and allows the formation of granulation tissue rich in proangiogenic factors, including transforming growth factor β (TGF-β) and vascular endothelial growth factor A (VEGF-A), which may have an impact on anastomosis healing. The present study comprised 25 patients (27 in total, 2 succumbed to complications following surgery) who underwent two-stage esophagectomy for squamous cell carcinoma in the Department of Gastrointestinal and General Surgery, Wrocław Medical University (Wrocław, Poland) between January 2007 and December 2012. Immunohistochemical staining for VEGF-A and TGF-β was performed to evaluate esophageal wall specimens at the time of esophagostomy construction and prior to anastomosis, in which the cervical esophagus was connected with the colon or ileum. At the time of reconstructive surgery, a significant increase in microvessel density was observed in all esophageal specimens (P<0.03). Significant differences were also identified in the immunohistochemical staining intensity of TGF-β and VEGF-A in the epithelium of all esophageal specimens between biopsies obtained from normal esophageal tissues at the time of esophagectomy and during reconstructive surgery. Delayed anastomosis construction provides an advantage for the esophageal stump to accumulate proangiogenic growth factors, which overlap with the subsequent proliferative stage of the anastomosed tissue and thus supports its recovery, creating an optimal environment for the healing of any fistulas.

Novel Link between Inhibition of Angiogenesis and Tolerance to Vascular Stress

The functional integrity of the vascular endothelium is an essential component required for the maintenance of vascular health, thus counteracting the onset of vascular diseases, including atherosclerosis and vascular complications of diabetes. In light of this important role, the vascular endothelium is expected to have a self-defense system. One candidate factor of such a system is vasohibin-1 (VASH1), a protein that is preferentially expressed in vascular endothelial cells (ECs). The unique features of VASH1 are its anti-angiogenic activity and ability to promote the stress tolerance and survival of ECs. This review summarizes current knowledge regarding VASH1 in terms of its roles in maintaining vascular integrity and protecting the vasculature against various forms of stress.