Expression of maspin is associated with the intestinal type of gastric adenocarcinoma

SERPINB5 is a novel serum diagnostic biomarker for gastric high-grade intraepithelial neoplasia and plays a role in regulation of macrophage phenotypes

BACKGROUND

Gastric cancer (GC) develops from gastric precancerous lesions (GPL), and early diagnosis and treatment at the premalignant stage may achieve a higher benefit‒cost ratio with a reduced necessity for surgery. However, reliable noninvasive screening biomarkers of GPL are currently lacking.

METHODS

The marker genes of GPL encoding extracellular proteins were identified by bioinformatics analysis and further verified by immunofluorescence and immunohistochemistry assays. Serum samples were collected to measure the levels of SERPINB5, the diagnostic efficacy of which was assessed by the area under the receiver operating characteristic (ROC) curve (AUC). Finally, the effect of SERPINB5 on the phenotypic conversion of macrophages was verified by public data and in vitro experiments.

RESULTS

SERPINB5 was identified as an extracellular biomarker of GPL that had good diagnostic efficacy. High expression of SERPINB5 was observed in the epithelial cells and adjacent extracellular matrix on sections of gastric high-grade intraepithelial neoplasia (HGIN). Importantly, SERPINB5 determined in serum was significantly increased in the HGIN group, and the AUC for discriminating between HGIN and chronic gastritis or low-grade intraepithelial neoplasia was 0.9936 and 0.9750, respectively. Moreover, SERPINB5 expression was positively correlated with macrophage infiltration, and M1 marker NOS2 expression, but negatively correlated with M2 marker CSF1R expression. In THP-1-derived macrophages, SERPINB5 upregulated expression of M1-related cytokines TNF-α and IL-12, and M1 marker CD86, but suppressed production of M2-related cytokines TGF-β and IL-10.

CONCLUSIONS

Our study provides evidence that SERPINB5 may serve as a promising noninvasive serum biomarker for gastric HGIN screening and regulate macrophage phenotype conversion.

P176S Mutation Rewires Electrostatic Interactions That Alter Maspin Functionality

Maspin is known to regress tumors by inhibiting angiogenesis; however, its roles have been reported to be context- and sequence-dependent. Various proteins and cofactors bind to maspin, possibly explaining its conflicting roles. Moreover, polymorphic forms of maspin have also been linked to tumor regression and survival; for instance, maspin with Ser at 176 (maspin-S176) promotes tumors, while maspin with Pro at 176 (maspin-P176) has opposing roles in cancer pathogenesis. With the help of long molecular dynamics simulations, a possible link between polymorphic forms and tumor progression has been established. First, maspin is dynamically stable with either amino acid at the 176 position. Second, differential contacts have been observed among various regions; third, these contacts have significantly altered the electrostatic energetics of various residues; finally, these altered electrostatics of maspin-S176 and maspin-P176 rewire the polar contacts that abolished the allosteric control of the protein. By combining these factors, the altered electrostatics substantially affect the localization and preference of maspin-binding partners, thus culminating in a different maspin-protein(cofactor)-interaction landscape that may have been manifested in previous conflicting reports. Here, the underlying reason has been highlighted and discussed, which may be helpful for better therapeutic manipulation.

Analysis of co-expression networks for circular RNAs and mRNAs reveals that circular RNAs hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 are candidate oncogenes in gastric cancer

Accumulating evidence has suggested that circular RNAs (circRNAs) play important roles in oncogenesis and tumor progression. However, our knowledge of circRNAs in gastric cancer (GC) remains limited. To investigate circRNAs involved in GC oncogenesis, we examined differentially-expressed circRNAs and mRNAs in GC tissues and paired noncancerous mucosa tissues using circRNA and mRNA microarrays. Next, we built gene co-expression networks according to the degree of correlation to predict the critical circRNAs in GC. Through bioinformatics analysis, we observed three newly identified circRNAs that are substantially upregulated in GC: hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15. Additionally, hsa_circ_0047905 and hsa_circ_0138960 positively correlated with their parental gene mRNA. Knockdown of hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 in GC cells, resulted in downregulation of parental gene expression. Functional assays suggested that inhibition of these three circular RNAs suppresses GC cell proliferation and invasion in vitro. Those findings suggest that hsa_circ_0047905, hsa_circ_0138960 and has-circRNA7690-15 might act as tumor promoters in the pathogenesis of gastric cancer.

The roles of maspin expression in gastric cancer: a meta- and bioinformatics analysis

Maspin is a mammary serine protease inhibitor that is encoded by human SERPINB5 gene, and inhibits invasion and metastasis of cancer cells as a tumor suppressor. We performed a systematic meta- and bioinformatics analysis through multiple online databases up to Feb 10, 2017. We found down-regulated maspin expression in gastric cancer, compared with normal mucosa and dysplasia (p < 0.05). Maspin expression was negatively correlated with depth of invasion, TNM staging and dedifferentiation of gastric cancer (p < 0.05). Nuclear maspin expression was higher in intestinal- than diffuse-type carcinoma (p < 0.05). An inverse association between maspin expression and unfavorable overall survival was found in patients with gastric cancer (p < 0.005). According to bioinformatics databases, SERPINB5 mRNA expression was higher in gastric cancer than normal tissues (p < 0.05), and negatively correlated with depth of invasion, TNM staging and dedifferentiation of gastric cancer (p < 0.05). According to KM plotter, we found that a higher SERPINB5 expression was positively correlated with overall and progression-free survival rates of all cancer patients, even stratified by aggressive parameters (p < 0.05). These findings indicated that maspin expression might be employed as a potential marker to indicate gastric carcinogenesis, subsequent progression, and even prognosis.

Maspin: molecular mechanisms and therapeutic implications

Maspin, a non-inhibitory member of the serine protease inhibitor superfamily, has been characterized as a tumor suppressor gene in multiple cancer types. Among the established anti-tumor effects of Maspin are the inhibition of cancer cell invasion, attachment to extracellular matrices, increased sensitivity to apoptosis, and inhibition of angiogenesis. However, while significant experimental data support the role of Maspin as a tumor suppressor, clinical data regarding the prognostic implications of Maspin expression have led to conflicting results. This highlights the need for a better understanding of the context dependencies of Maspin in normal biology and how these are perturbed in the context of cancer. In this review, we outline the regulation and roles of Maspin in normal and developmental biology while discussing novel evidence and emerging theories related to its functions in cancer. We provide insight into the immense therapeutic potential of Maspin and the challenges related to its successful clinical translation.

Prognostic value of nuclear maspin expression for adjuvant 5-fluorouracil-based chemotherapy in advanced gastric cancer

To assess the prognostic and predictive value of maspin expression for the clinical response to 5-fluorouracil (5-FU)-based chemotherapy in advanced gastric cancer (GC) patients, the expression of maspin in primary tumors from 127 patients with advanced GC was examined using immunohistochemistry. Of the 127 patients, 74 were treated with surgery alone and 53 received additional adjuvant 5-FU-based chemotherapy. Nuclear and cytoplasmic maspin expression was observed in 46.5 (59/127) and 68.5% (87/127) of patients, respectively. Nuclear maspin immunoreactivity was significantly associated with larger tumor size (p=0.036), the depth of tumor invasion (p=0.02) and lymph node metastasis (p=0.002). Cytoplasmic maspin immunoreactivity was associated with tumor cell differentiation but not with the other clinicopathological variables. Nuclear maspin immunoreactivity had a significant association with overall survival (OS). Among the nuclear maspin-expressing patients, those who were treated with 5-FU-based adjuvant chemotherapy showed significantly longer OS than those without chemotherapy (p=0.0004). In conclusion, nuclear maspin expression is associated with adverse clinical outcomes in patients with advanced GC. Patients with positive nuclear maspin expression may be more responsive to adjuvant 5-FU chemotherapy.