Maintenance of cellular annexin A1 level is essential for PI3K/AKT/mTOR-mediated proliferation of pancreatic beta cells

Annexin A1 (AnxA1, also known as lipocortin-1), is a calcium-dependent phospholipid binding protein with diverse functions. Previous studies have indicated that AnxA1 is associated with age-related β-cell dysfunction and aging, which lead to decreased β-cell proliferation capacity. However, it has been uncertain whether AnxA1 affects the proliferation of pancreatic beta (β) cells. In the present study, we reduced AnxA1 expression in the MIN6 islet β-cell line using small interfering RNA (AnxA1-siRNA), then measured cell cycle distribution and cellular proliferation. We also measured the expression levels of cell cycle-related proteins such as cyclin D1, cyclin E, and cyclin-dependent kinase 2 (CDK2) by Western blot analysis. We investigated the phosphatidylinositol 3-kinase (PI3K)/ serine/threonine protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway to explore the potential mechanism underlying the observed effects. Knockdown of AnxA1 expression using siRNA reduced the rates of MIN6 cell proliferation. The proportions of cells in S and G2/M phases also decreased upon inhibition of AnxA1. Moreover, AnxA1 protein expression in MIN6 cells was positively related to the protein levels of cyclin D1, cyclin E, and CDK2. Activation of the PI3K/Akt/mTOR signaling pathway by AnxA1 may be involved in the signaling cascade to regulate cell proliferation. This study identified a positive correlation between AnxA1 protein and pancreatic β-cell proliferation. AnxA1 protein expression might affect the proliferation of MIN6 cells via regulation of cyclin D1, cyclin E, and CDK2 proteins, as well as the PI3K/Akt/mTOR signaling pathway.

[Clinical significance of syndecan-1 and syndecan-2 expression in gallbladder squamous cell/adenosquamous carcinoma and adenocarcinoma]

Objective: To investigate the expression of syndecan-1 and syndecan-2 and their clinicopathological significance in patients with gallbladder squamous cell (SC)/adenosquamous carcinoma (ASC) and adenocarcinoma (AC). Methods: A total of 126 patients with SC/ASC (n=46) and AC (n=80) were included in this study. The expression levels of syndecan-1 and syndecan-2 were detected by Envison™ immunohistochemistry assay. The clinical and prognostic significance of syndecan-1 and syndecan-2 were analyzed. Results: In the 46 SC/ASC samples, syndecan-1 and syndecan-2 were positively expressed in 29 (63.0%) and 28 (60.9%) tumor tissues, respectively. (Positive expression was defined based on the staining in the component of squamous cell carcinoma. That is to say, the tissue which adenocarcinoma part was positively stained, but squamous cell carcinoma part was negatively stained is also regarded as negative.) In the 80 AC samples, 47 (58.8%) cases showed syndecan-1 positive expression, and 51 (63.8%) showed syndecan-2 positive expression. There was no significant difference in the positive rates of syndecan-1 and syndecan-2 between SC/ASC and AC groups (P>0.05 for all). The levels of syndecan-1 and syndecan-2 were associated with tumor size, TNM staging, lymph node metastasis, invasion of adjacent tissue, and surgical procedures in SC/ASC patients (P<0.05 for all). However, their expression was associated with tumor differentiation, tumor size, TNM staging, lymph node metastasis, invasion of adjacent tissue, and surgical procedures in AC patients (P<0.05 for all). The Kaplan-Meier survival analysis of SC/ASC and AC patients revealed that the average survival time for patients with positive syndecan-1 and syndecan-2 expression was significantly shorter than that of those with negative expression (P<0.01 for all). Cox multivariate analysis indicated that syndecan-1 and syndecan-2 expression were independent unfavorable prognostic factors for SC/ASC and AC patients (P<0.05 for all). Conclusion: The syndecan-1 and syndecan-2 expression are associated with the tumor progression and poor prognosis in patients with gallbladder SC/ASC and AC.

Adsorption dynamics and rate assessment of volatile organic compounds in active carbon

A new form of the pseudo-second-order kinetic model in terms of the adsorbed rate parameter and the THz parameter.

[Plasma level and effects of thromboxane A2 and 6-keto-PGF1 alpha in patients with acute obstructive suppurative cholangitis]

The changes of the plasma thromboxane B2 (TXB2) and 6-keto-PGF1 alpha, the stable metabolites of TXA2 and PGI2, respectively and their effects on platelet counts, platelet aggregation and hypotension were studied in patients with AOSC. The results showed that the plasma TXB2, 6-keto-PGF1 alpha and 6-keto-PGF1 alpha/TXB2 ratios in these patients were markedly increased, however, the platelet counts markedly decreased and platelet aggregation inhibited significantly. After operation, they recovered to normal gradually. There were negative correlation between TXB2 with platelet count and 6-keto-PGF1 alpha with platelet aggregation, as well as both TXB2 and 6-keto-PGF1 alpha with blood pressure. TXA2 was an important factor which lead to platelet decrement and take part in the pathological course of disseminated intravascular coagulation (DIC) and multiple organ failure (MOF), but PGI2 might play an important role in improving microcirculation and preventing DIC and MOF through the inhibition of platelet aggregation.