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Bone metastases from gastric cancer (GC) are considered a relatively uncommon finding; however, they are related to poorer prognosis. Both primary GC and its metastatic progression rely on angiogenesis. Several lines of evidence from GC patients strongly support the involvement of mast cells (MCs) positive to tryptase (MCPT) in primary gastric tumor angiogenesis. Recently, we analyzed infiltrating MCs and neovascularization in bone tissue metastases from primary GC patients, and observed a significant correlation between infiltrating MCPT and angiogenesis. Such a finding suggested the involvement of peritumoral MCPT by infiltrating surrounding tumor cells, and in bone metastasis angiogenesis from primary GC. Thus, an MCPT-stimulated angiogenic process could support the development of metastases in bone tissue. From this perspective, we aim to review the hypothetical involvement of tumor-infiltrating, peritumoral MCPT in angiogenesis-mediated GC cell growth in the bone microenvironment and in tumor-induced osteoclastic bone resorption. We also focus on the potential use of MCPT targeting agents, such as MCs tryptase inhibitors (gabexate mesylate, nafamostat mesylate) or c-KitR tyrosine kinase inhibitors (imatinib, masitinib), as possible new anti-angiogenic and anti-resorptive strategies for the treatment of GC patients affected by bone metastases.

Aim: To evaluate vascular endothelial growth factor (VEGF) and tryptase in hepatocellular cancer (HCC) before and after trans-arterial chemoembolization (TACE)., Methods: VEGF and tryptase serum concentrations were assessed from 71 unresectable HCC patients before and after hepatic TACE performed by binding DC-Beads(®) to doxorubicin. VEGF levels were examined for each serum sample using the Quantikine Human VEGF-enzyme-linked immuno-absorbent assay (ELISA), whereas tryptase serum concentrations were assessed for each serum sample by means of fluoro-enzyme immunoassay (FEIA) using the Uni-CAP100 tool. Differences between serum VEGF and tryptase values before and after TACE were evaluated using Student t test. Person's correlation was used to assess the degree of association between the two variables., Results: VEGF levels and serum tryptase in HCC patients before TACE had a mean value and standard deviation (SD) of 114.31 ± 79.58 pg/mL and 8.13 ± 3.61 μg/L, respectively. The mean levels and SD of VEGF levels and serum tryptase in HCC patients after TACE were 238.14 ± 109.41 pg/mL and 4.02 ± 3.03 μg/L. The changes between the mean values of concentration of VEGF and tryptase before treatment and after treatment was statistically significant (P < 0.000231 and P < 0.00124, by Wilcoxon-Mann-Whitney respectively). A significant correlation between VEGF levels before and after TACE and between tryptase levels before and after TACE was demonstrated (r = 0.68, P = 0.003; r = 0.84, P = 0.000 respectively)., Conclusion: Our pilot results suggest that the higher serum VEGF levels and the lower tryptase levels following TACE may be potential biomarkers changing in response to therapy.

Mast cells (MCs), located ubiquitously near blood vessels, are descended from CD34(+) hematopoietic stem cells. Initially, although their role has been well defined in hypersensitivity reactions, the discovery of their sharing in both innate and adaptive immunity has allowed to redefine their crucial interplay on the regulatory function between inflammatory and tumor cells through the release of mediators granule-associated (mainly tryptase and vascular endothelial growth factor). In particular, in several animal and human malignancies it has been well demonstrated that activated c-Kit receptor (c-KitR) and tryptase (an agonist of the proteinase-activated receptor-2) take pivotal part in tumor angiogenesis after the MCs activation, contributing to tumor cells invasion and metastasis. In this review, we focused on crucial MCs density (MCD) role in colorectal cancer (CRC) development and progression angiogenesis-mediated; then, we will analyze the principal studies that have focused on MCD as possible prognostic factor. Finally, we will consider a possible role of MCD as novel therapeutic target mainly by c-KitR tyrosine kinase inhibitors (imatinib, masitinib) and tryptase inhibitors (gabexate and nafamostat mesylate) with the aim to prevent CRC progression.

Hepatocellular carcinoma (HCC) is the fifth most common cause of cancer in the world. According to Barcelona Clinic Liver Cancer modified criteria, patients with early stage disease are candidate to radiofrequency ablation (RFA), while patients with intermediate stage HCC are usually treated by transarterial chemoembolization (TACE). TACE and RFA induce a transient devascularisation effect followed by strong neo-angiogenic stimulus. In fact, after these procedures, it has been demonstrated an up-regulation of pro-angiogenic and growth factors such as vascular endothelial growth factor-A, which might contribute to accelerated progression in patients with incomplete response. Several studies have demonstrated that MAP-kinase and AKT pathways, in addition to neo-angiogenesis, have an important role in the development of HCC. In advanced HCC, anti-angiogenic therapy and tyrosine kinases inhibitors showed potential clinical benefit. Actually, a number of clinical studies are ongoing testing these agents in combination with TACE or RFA. In this paper, we have reviewed the most recent preclinical and clinical results of such trials.