A decreased ratio between serum levels of the antagonistic angiopoietins 1 and 2 indicates tumour progression of malignant melanoma

O-GlcNAc Modification and Its Role in Diabetic Retinopathy

Diabetic retinopathy (DR) is a leading complication in type 1 and type 2 diabetes and has emerged as a significant health problem. Currently, there are no effective therapeutic strategies owing to its inconspicuous early lesions and complex pathological mechanisms. Therefore, the mechanism of molecular pathogenesis requires further elucidation to identify potential targets that can aid in the prevention of DR. As a type of protein translational modification, O-linked β-N-acetylglucosamine (O-GlcNAc) modification is involved in many diseases, and increasing evidence suggests that dysregulated O-GlcNAc modification is associated with DR. The present review discusses O-GlcNAc modification and its molecular mechanisms involved in DR. O-GlcNAc modification might represent a novel alternative therapeutic target for DR in the future.

Anti-melanoma effects of concomitant inhibition of SIRT1 and SIRT3 in BrafV600E/PtenNULL mice

Novel therapeutic strategies are required for the effective and lasting treatment of metastatic melanoma, one of the deadliest skin malignancies. In this study, we determined the anti-melanoma efficacy of 4'-bromo-resveratrol (4'-BR), which is a small molecule dual inhibitor of SIRT1 and SIRT3 in a Braf^V600E/Pten^NULL mouse model that recapitulates human disease, including metastases. Tumors were induced by topical application of 4-hydroxy-tamoxifen on shaved backs of 10-week-old mice, and the effects of 4'-BR (5-30 mg/kg b.wt.; intraperitoneally; 3d/week for 5 weeks) were assessed on melanoma development and progression. We found that 4'-BR at a dose of 30 mg/kg significantly reduced size and volume of primary melanoma tumors, as well as lung metastasis, with no adverse effects. Further, mechanistic studies on tumors showed significant modulation in markers of proliferation, survival and melanoma progression. As SIRT1 and SIRT3 are linked to immunomodulation, we performed differential gene expression analysis via NanoString PanCancer Immune Profiling panel (770 genes). Our data demonstrated that 4'-BR significantly downregulated genes related to metastasis-promotion, chemokine/cytokine-regulation, and innate/adaptive immune functions. Overall, inhibition of SIRT1 and SIRT3 by 4'-BR is a promising anti-melanoma therapy with anti-metastatic and immunomodulatory activities warranting further detailed studies, including clinical investigations.

Angiopoietin-1 is associated with a decreased risk of lymph node metastasis in early stage cervical cancer

OBJECTIVES

Lymph node metastasis (LNM) is an important determinant of prognosis in patients with cervical cancer. Members of the angiopoietin family have been demonstrated to regulate tumor-associated angiogenesis and lymphangiogenesis. This study aimed to investigate the expression levels of angiopoietin-1 (ANG1) and angiopoietin-2 (ANG2) in clinically early stage of cervical cancer along with their correlations with LNM.

METHODS

In total, 124 human cervical cancer cases classified into stage IA-IIB in accordance with the International Federation of Gynecology and Obstetrics (FIGO) 2009 staging criteria were included. ANG1 and ANG2 expression levels in the tumor sections were assessed by immunohistochemistry (IHC). Univariate and multivariate logistic regression models, including age at diagnosis, FIGO stage, tumor size, pathological type, histological grading, depth of stromal invasion, lymph-vascular space invasion (LVSI) and the expression status of ANG1 and ANG2, were used to evaluate the odds ratios (ORs) for LNM.

RESULTS

ANG1 and ANG2 were positively expressed in 75 (60.5%) and 89 (71.8%) cervical cancers respectively, with predominant staining in the cytoplasm. ANG1 expression was significantly decreased in tumors with LNM, while no correlation was observed between ANG2 expression and LNM. More importantly, the multivariate logistic regression analysis demonstrated that high ANG1 expression was an independent protective factor of LNM (OR 0.107, 95% confidential interval [CI] 0.020~0.567), while LVSI was an independent risk factor of LNM (OR 34.313, 95% CI 5.914~199.092).

CONCLUSION

ANG1 is associated with a significantly decreased risk of LNM in early stage cervical cancer. The predictive value and role of ANG1 in LNM needs to be further investigated in future studies.

Uveal Melanoma, Angiogenesis and Immunotherapy, Is There Any Hope?

Uveal melanoma is considered a rare disease but it is the most common intraocular malignancy in adults. Local treatments are effective, but the systemic recurrence rate is unacceptably high. Moreover, once metastasis have developed the prognosis is poor, with a 5-year survival rate of less than 5%, and systemic therapies, including immunotherapy, have rendered poor results. The tumour biology is complex, but angiogenesis is a highly important pathway in these tumours. Vasculogenic mimicry, the ability of melanomas to generate vascular channels independently of endothelial cells, could play an important role, but no effective therapy targeting this process has been developed so far. Angiogenesis modulates the tumour microenvironment of melanomas, and a close interplay is established between them. Therefore, combining immune strategies with drugs targeting angiogenesis offers a new therapeutic paradigm. In preclinical studies, these approaches effectively target these tumours, and a phase I clinical study has shown encouraging results in cutaneous melanomas. In this review, we will discuss the importance of angiogenesis in uveal melanoma, with a special focus on vasculogenic mimicry, and describe the interplay between angiogenesis and the tumour microenvironment. In addition, we will suggest future therapeutic approaches based on these observations and mention ways in which to potentially enhance current treatments.

Angiopoietin-like protein 1 inhibits epithelial to mesenchymal transition in colorectal cancer cells via suppress Slug expression

The role of ANGPTL1 in cancer development is still little known, especially in colorectal cancer (CRC). We investigated the clinical significance of ANGPTL1 expression in CRC tissues and its potential role in the progression of epithelial to mesenchymal transition (EMT) in CRC cells, which has not been reported to our knowledge. ANGPTL1 expression in CRC tissues was much lower that than in paired adjacent normal tissues by IHC, WB and qRT-PCR assays. ANGPTL1 positive expression was negatively associated with tumor size (P = 0.034), T stage (P = 0.015), lymph nodes metastasis (P = 0.045) and TNM stage (P = 0.009) and poor prognosis of CRC patients (P = 0.003). In vitro, ANGPTL1 showed decreasing expression in CRC cell lines from primary tumor to ascites metastasis. Meanwhile, ANGPTL1 silencing enhanced EMT in HCT116 cells followed with the increase of Slug, Fibronectin and Vimentin, the decrease of E-cad, and the enhancement of EMT-like cell morphology and cell invasion and migration. Low ANGPTL1 expression is closely associated with multiple clinical significance and prognosis of CRC patients. ANGPTL1 inhibits EMT of CRC cells via inhibiting E-cad suppressor Slug expression.

Role of Angiopoietins and Tie-2 in Diabetic Retinopathy

OBJECTIVE

The aim of this study was to determine the serum levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), soluble vascular endothelial tyrosine kinase receptor (Tie-2) and vascular endothelial growth factor (VEGF), in the serum of type 2 diabetic patients having non-proliferative (NPDR) or proliferative diabetic retinopathy (PDR).

METHODS

One hundred patients with type 2 diabetes mellitus were involved in this cross-sectional study. They were classified into 25 diabetic patients without retinopathy, 35 patients with NPDR and 40 PDR patients. The study was carried out in the outpatients clinic of the Research Institute of Ophthalmology, Giza, Egypt from August 2016 through May 2017. Serum VEGF, Ang-1, Ang-2 and Tie-2 receptor levels were assayed using enzyme linked immunosorbent assay (ELISA). Data were analyzed by SPSS version 20 and Microsoft Excel (Version 10) using ANOVA, Harman's single factor test, and Pearson's Product Moment Correlation.

RESULTS

The serum levels of Ang-2 and VEGF were significantly elevated in NPDR groups and PDR group compared to diabetics without retinopathy groups (p<0.001). The serum levels of Ang-1 were significantly higher in the NPDR group compared to the diabetics without retinopathy groups (p<0.01), while no significant difference was observed between the PDR and diabetics without retinopathy groups. Ang-1/Ang-2 ratio was the lowest in the PDR group compared to the NPDR and diabetics without retinopathy groups. The serum levels of Tie-2 were not significantly changed among the three studied groups, serum Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups.

CONCLUSION

The angiopoietin/Tie system and VEGF are essential features in the commencement and development of PDR.

Correlations of EGF G1380A, bFGF C754G and VEGF T460C polymorphisms with malignant melanoma susceptibility and prognosis: A case-control study

This case-control study aims to investigate the correlations of EGF G1380A, bFGF C754G and VEGF T460C polymorphisms with the susceptibility and prognosis of malignant melanoma. A total of 153 patients with multiple primary melanomas were collected as the case group and another 170 healthy individuals were selected as the control group. ELISA and PCR-RFLP were performed to test the serum level of VEGF and to analyze the genotype as well as allele frequencies of VEGF T460C, EGF G1380A, and bFGF C754G, respectively. The patients were assigned into complete remission (CR), partial remission (PR) and non-remission groups after treatment. HE and CD34 staining were conducted in tissue samples of CR and PR patients. Event-free survival (EFS) and overall survival (OS) were measured. AA genotype of EGF G1380A and GG genotype of bFGF C754G had higher frequency distribution in the case group than the control group. Patients with AA genotype of EGF G1380 and GG genotype of bFGF C754G had an elevated VEGF level in comparison to other genotypes. Patients with GA+GG genotypes of EGF G1380A and CG+CC genotypes of bFGF C754G had higher EFS and OS than those with AA genotype and those with GG genotype, respectively. According to the haplotype analysis, the case group had a notably higher frequency of TAG and CAG along with while lower frequency of TGG and CGC compared with the control group. Logistic regression analysis revealed that the polymorphisms of EGF G1380A and bFGF C754G as well as the haploid TAG increased the susceptibility of malignant melanoma. The results indicated that EGF G1380A and bFGF C754G gene polymorphisms were associated with the susceptibility and prognosis of malignant melanoma, and that the polymorphisms of EGF G1380A and bFGF C754G as well as the haploid TAG increased the susceptibility of malignant melanoma.

Role of rare germline copy number variation in melanoma-prone patients

AIM

This work evaluates a possible causative role for germline copy number variants (CNVs) in melanoma predisposition.

PATIENTS & METHODS

A total of 41 melanoma-prone Brazilian patients were investigated for CNVs using 850K single nucleotide polymorphism arrays.

RESULTS

Ten rare CNVs were identified in nine patients, comprising 54 known genes, mostly related to cancer. In silico analyses revealed gene enrichment for cellular development and growth, and proliferation, highlighting five genes directly associated with the melanoma phenotype (ANGPT1, IDH1, PDE5A, HIST1H1B and GCNT2).

CONCLUSION

Patients harboring rare CNVs exhibited a decreased age of disease onset, in addition to an overall higher skin cancer predisposition. Our findings suggest that rare CNVs contribute to melanoma susceptibility, and should be taken into account when investigating cancer risk factors.

Angiogenesis in melanoma: an update with a focus on current targeted therapies

Angiogenesis plays a crucial role in melanoma metastasis and progression. In recent years, numerous studies have investigated the prognostic and clinical significance of this phenomenon, and the development of molecular techniques has enabled us to achieve a better understanding of angiogenesis in melanoma. Herein, we review the current state of knowledge regarding angiogenesis in melanoma, including the pathophysiological, histological and immunohistochemical aspects of this phenomenon. We also review the molecular pathways involved in angiogenesis and the interplay between different components that might be manipulated in the future development of efficient targeted therapies. Recently developed targeted antiangiogenic therapies in clinical trials and included in the treatment of advanced-stage melanoma are also reviewed.

Circulating serum levels of angiopoietin-1 and angiopoietin-2 in nasopharynx and larynx carcinoma patients

We aimed to determine the serum levels of angiogenic factors, namely angiopoietins, in nasopharyngeal and laryngeal carcinoma patients. We also aimed to seek the relation of these molecules with tumor grade and their utility as diagnostic biomarkers. We evaluated angiopoietin 1 and 2 levels innasopharynx and larynx cancer patients before treatment. Angiopoietin 2 levels were significantly elevated in larynx carcinoma patients and tended to be elevated in nasopharynx cancer patients compared with healthy controls. However, angiopoietin 1 levels were similar in cancer patients and controls. Angiopoietin 1 levels were significantly higher in nasopharyngeal cancer patients with advanced stages compared to earlier stages. On the other hand, angiopoietin 2 levels were similar in advanced and earlier stage cancer patients.

Effects of laser photocoagulation on serum angiopoietin-1, angiopoietin-2, angiopoietin-1/angiopoietin-2 ratio, and soluble angiopoietin receptor Tie-2 levels in type 2 diabetic patients with proliferative diabetic retinopathy

AIM

To determine the effects of laser photocoagulation on serum levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), soluble angiopoietin receptor Tie-2 (Tie-2), Ang-1/Ang-2 ratio and vascular endothelial growth factor (VEGF) in patients with type 2 diabetes mellitus (T2DM) and proliferative diabetic retinopathy (PDR). We also explored the role of the Ang/Tie system in PDR.

METHODS

160 patients with T2DM, including 50 patients with non-diabetic retinopathy (NDR), 58 patients with non-proliferative diabetic retinopathy (NPDR), and 52 patients with PDR were enrolled in this study. Serum Ang-1, Ang-2, Tie-2 receptor and VEGF levels were measured using enzyme-linked immunosorbent assays for all patients and were repeated in 26 patients who underwent laser photocoagulation two months after the procedure.

RESULTS

The median levels of Ang-2 and VEGF in serum were significantly higher in the NPDR group (4.23 ng/mL and 303.2 pg/mL, respectively) compared to the NDR group (2.67 ng/mL and 159.8 pg/mL, respectively, P<0.01), with the highest level in the PDR group (6.26 ng/mL and 531.2 pg/mL, respectively, P<0.01). The median level of Ang-1 was significantly higher in the NPDR group (10.77 ng/mL) compared to the NDR group (9.31 ng/mL) and the PDR groups (9.54 ng/mL) (P<0.05), while no difference was observed between the PDR and NDR groups. Ang-1/Ang-2 ratio of PDR group was lowest in three groups (1.49 vs 2.69 and 2.90, both P<0.01). The median level of Tie-2 was not significantly different among three groups (P>0.05). Ang-2 was positively correlated with VEGF and Tie-2 in the PDR and NPDR groups (both P<0.05). Among the 26 patients who underwent laser photocoagulation, serum Ang-2 and VEGF levels significantly decreased (both P<0.05), whereas serum Ang-1 level and Ang-1/Ang-2 ratio were weakly increased (P>0.05). The median levels of Ang-2 and VEGF in serum were highest in PDR group, however, Ang-1/Ang-2 ratio of PDR group was lowest in three groups.

CONCLUSION

Laser photocoagulation can reduce serum Ang-2 and VEGF levels. The Ang/Tie system and VEGF play an important role in the development and progression of T2DM patients with PDR.

Mechanisms of tumour vascularization in cutaneous malignant melanoma: clinical implications

Malignant melanoma represents < 10% of all skin cancers but is responsible for the majority of skin-cancer-related deaths. Metastatic melanoma has historically been considered as one of the most therapeutically challenging malignancies. Fortunately, for the first time after decades of basic research and clinical investigation, new drugs have produced major clinical responses. Angiogenesis has been considered an important target for cancer treatment. Initial efforts have focused primarily on targeting endothelial and tumour-related vascular endothelial growth factor signalling. Here, we review different mechanisms of tumour vascularization described in melanoma and discuss the potential clinical implications.

Dual VEGF/VEGFR inhibition in advanced solid malignancies: clinical effects and pharmacodynamic biomarkers

Our prior phase I study of the combination of vascular endothelial growth factor (VEGF) antibody, bevacizumab, and VEGF receptor (VEGFR) inhibitor, sunitinib, in advanced solid tumors identified an encouraging response evaluation. An expansion phase of this study was thus undertaken to obtain further safety data, response assessment and characterization of pharmacodynamic biomarkers in melanoma, renal, and adrenal carcinoma patients. Patients with metastatic solid tumors received sunitinib (37.5 mg/d, 4 wk on/2 wk off) and bevacizumab (5 mg/kg intravenously every 2 wk). Responses were assessed every 2 cycles. Serum levels of angiogenic molecules were measured using ELISA assays. Twenty-two patients were enrolled, including 11 melanoma, 5 renal cell carcinoma (RCC), 5 adrenal cancer, and 1 angiosarcoma. Grade 3 or higher adverse events were observed in 15 patients, including hypertension (41%), thrombocytopenia (23%), and fatigue (14%). Three RCC patients, and 1 melanoma patient developed thrombotic microangiopathy (TMA). Partial response (PR) occurred in 21% patients, including melanoma (2), adrenal (1), and renal (1) carcinomas. Overall, 6 patients demonstrated some reduction in their tumor burden. Serum VEGF and several other proangiogenic proteins declined over the first 4 wk of treatment whereas the putative VEGF-resistant protein, prokineticin-2, increased over 10-fold. Occurrence of TMA related to dual VEGF/VEGFR inhibition can result from systemic or nephron specific injury even in non-renal malignancies. While the combination of sunitinib and bevacizumab was clinically efficacious in renal cell carcinoma and melanoma, the observance of microangiopathy, even in non-RCC patients, is a significant toxicity that precludes further clinical development.

Angiogenesis and the tumor microenvironment: vascular endothelial growth factor and beyond

Our understanding of the dynamic tumor microenvironment (TME) has improved exponentially over the last few decades. In addition to traditional cytotoxic agents, anti-cancer strategies now include numerous molecular-targeted drugs that modulate distinct elements of the TME. Angiogenesis is an underlying promoter of tumor growth, invasion, and metastases. From traditional and emerging angiogenic cytokines and their receptors to novel immune checkpoint inhibitors, regulation of the tumor microenvironment is potentially key in countering tumor progression. In this article, an overview of the architecture of the TME and the orchestration of angiogenesis within the TME is provided. Additionally, traditional and novel angiogenic targets of current interest within the TME are reviewed.

Angiopoietins in angiogenesis

Tie-1 and Tie-2 tyrosine kinase receptors are expressed specifically on vascular endothelial cells and on a certain subtype of macrophages implicated in angiogenesis, thus, they have been a major focus of angiogenesis research. Tie-1 and Tie-2 are essential for vascular maturation during developmental, physiological and pathological angiogenesis. Angiopoietin 1-4 (Ang-1-4) have been identified as bona fide ligands of the Tie-2 receptor, while Tie-1 remains an orphan receptor which is able to heterodimerize with Tie-2 and to modulate Tie-2 signal transduction. The most exhaustively studied angiopoietins are Ang-1 and Ang-2. Ang-1 is a critical player in vessel maturation and it mediates migration, adhesion and survival of endothelial cells. Ang-2 disrupts the connections between the endothelium and perivascular cells and promotes cell death and vascular regression. Yet, in conjunction with VEGF, Ang-2 promotes neo-vascularization. Hence, angiopoietins exert crucial roles in the angiogenic switch during tumor progression, and increased expression of Ang-2 relative to Ang-1 in tumors correlates with poor prognosis. Its central role in the regulation of physiological and pathological angiogenesis makes the angiopoietin/Tie signaling pathway a therapeutically attractive target for the treatment of vascular disease and cancer.

Malignant melanoma and its stromal nonimmune microecosystem

In recent years, rapid advances were reached in the understanding of a series of biologic signals influencing cutaneous malignant melanoma (CMM) cells. CMM is in close contact with a peculiar dermal extracellular matrix (ECM). Stromal cells store and release various structural ECM components. The impact on CMM growth and progression is mediated through strong and long-lasting effects of ECM products. This paper summarizes some peculiar aspects of the peri-CMM stroma showing intracytoplasmic loads in Factor XIIIa, CD34, versican, and α (IV) collagen chains. The restricted peri-CMM skin territory exhibiting such changes corresponds to the area showing neoangiogenesis and extravascular unicellular metastatic spread. The latter inconspicuous migratory CMM cells possibly correspond to CMM stem cells or to CMM cells with aberrant HOX gene expression. Their presence is associated with an increased risk for metastases in the regional sentinel lymph nodes. In conclusion, the CMM-stroma connection appears crucial to the growth regulation, invasiveness and initial metastatic spread of CMM cells. Although much remains to be learned in this field, the active intervention of the peri-CMM stroma is likely involved in the inconspicuous early metastatic migration of CMM cells.