The sialic acid-binding immunoglobulin-type lectin Siglec-15 is a promising target to cancer immunotherapy in several tumor types. The present study aimed to investigate Siglec-15 expression in gastric cancer (GC) patient tissue and to evaluate its clinical value. Siglec-15 expression was evaluated by immunohistochemistry with 71 patients. Siglec-15 staining was observed in tumor cells of 53 (74.64%) patients, with significant association with histologic classification and angiolymphatic invasion (p<0.05). Immunohistochemistry analysis also detected Siglec-15 in tumor-associated stroma cells (macrophages/myeloid cells). There was no significant association with outcomes parameters. Siglec-15 expression in well differentiated histological GC tissues and in the tumor microenvironment are potential targets to be further investigated as a novel prognostic factor for GC.

This work describes purification of a protease from the visceral mass of the mussel Mytella charruana as well as evaluation of its ability to hydrolyze milk casein to generate antimicrobial peptides. The enzyme showed pI of 4.1 and a single polypeptide band of 83.1 kDa after SDS-PAGE. Sequence similarities with tropomyosin and myosin from mollusks were detected. The protease showed a trypsin-like activity with optimal temperature of 40 °C and stability in a wide pH range (3.0-9.0). K was 4.28 ± 0.34 mM of the synthetic substrate N-benzoyl-dl-arginyl-ρ-nitroanilide, whereas V was 0.056 ± 0.001 nmol min. The enzyme hydrolyzed casein, and the hydrolysate inhibited the growth of Escherichia coli, Micrococcus luteus, Bacillus subtilis, and Klebsiella pneumoniae at a minimal inhibitory concentration of 5.0 µg mL. In conclusion, the visceral mass of M. charruana contains a trypsin-like protease that can generate peptides from casein that have a bacteriostatic effect.

Gastric cancer (GC) is the second most common cause of cancer-related deaths in the world. This study aims to investigate the differential tissue expression of ppGalNAc- T15 and to evaluate its possible association with clinical-pathological parameters and outcome of gastric adenocarcinoma patients. For these 70 patients were evaluated the expression by immunohistochemistry to ppGalNAc-T15. Our results showed that 33 (47.1%) patients were ppGalNAc-T15+ positive and 37 (52.9%) negative. Positive staining for ppGalNAc-T15 was significantly present in patients older than 60 years (P= 0.0306) and submitted to total gastrectomy (P=0.0087). Also, some results remained at the limit of significance as surgical standing (P = 0.0562) and histological grade (P=0.0549). Therefore, the ppGalNAc-T15 immunoreactivity can be useful to understand the prognosis of patients with gastric cancer.

The UDP-glucose 4-epimerase (GALE) is a glycosyltransferase, which acts on protein and lipid glycosylation in normal and neoplastic cells. This study is aimed at investigating the differential tissue expression of GALE and its possible association with clinical-pathological parameters and the outcome of gastric adenocarcinoma patients. Seventy-one patients were evaluated in relation to GALE expression by immunohistochemistry. Our results showed that 48 (67.6%) patients were GALE positive and 23 (32.4%) negative. Positive staining was present on well-differentiated and moderate-differentiated histological grade of gastric adenocarcinomas (p < 0.0001). There was no significant association with outcome parameters (p > 0.05). Besides that, our results corroborated with the validation cohort analysis, where the expression of GALE mRNA was also associated with the histological grade (p < 0.001). These results suggest a possible use of this enzyme as a biomarker for well and moderately differentiated tumors.

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