Porcine pancreatic stem cells (pPSCs) can be induced to insulin-secreting cells and therefore considered the most promising seeding cells for curing human diabetes in future. However, insufficient pPSCs number is one of the bottleneck problems before its clinical application. SerpinB1 is a serine protease inhibitor in neutrophils and can directly promote the proliferation of β cells. Whether SerpinB1 is involved in pPSC proliferation and differentiation remains unknown. The effects of SerpinB1 on pPSCs proliferation were measured by Cell Counting Kit-8, 5-ethynyl-2'-deoxyuridine, qRT-PCR, western blot, and flow cytometry assays. We found that pPSCs did not efficiently reach the S phase when SerpinB1 expression was knocked down with short hairpin RNA (sh-SerpinB1), the expression of Cyclin D1, CDK-2, and PCNA also decreased. Meanwhile, cell viability and proliferation ability were both declined. Further analyses showed that the expression level of phosphorylated STAT3/STAT3was downregulated, along with an upregulation of p53 and p21. We used a two-step induction method to induce pPSCs to insulin-secreting cells and found that SerpinB1 expression in insulin-secreting cells was higher than in pPSCs. Meanwhile, the protein expression level of phosphorylated STAT3/STAT3 was increased while p53 and p21 was decreased in induced insulin-secreting cells in comparison with control cells. The insulin-secreting cells derived from the sh-SerpinB1 cells secreted less insulin and showed poor sensitivity to high glucose than control group. However, the insulin-secreting cells derived from the ov-SerpinB1 cells has a quite contrary tendency. In conclusion, this study demonstrates that SerpinB1 promotes the proliferation of pPSCs through the STAT3 signaling pathway, and SerpinB1 is a key factor for maintaining the viability of pPSCs during the transition to insulin-secreting cells.

中文翻译：

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SerpinB1通过STAT3信号通路促进猪胰腺干细胞的增殖。

猪胰腺干细胞（pPSC）可以被诱导为分泌胰岛素的细胞，因此被认为是将来治愈人类糖尿病的最有希望的种子细胞。然而，不足的pPSCs数是其临床应用之前的瓶颈问题之一。SerpinB1是嗜中性粒细胞中的丝氨酸蛋白酶抑制剂，可以直接促进β细胞的增殖。SerpinB1是否参与pPSC增殖和分化仍然未知。通过细胞计数试剂盒8、5-乙炔基-2'-脱氧尿苷，qRT-PCR，western印迹和流式细胞术测定了SerpinB1对pPSCs增殖的影响。我们发现当用短发夹RNA（sh-SerpinB1）敲低SerpinB1表达时，pPSC不能有效地达到S期，Cyclin D1，CDK-2和PCNA的表达也下降。同时，细胞活力和增殖能力均下降。进一步的分析表明磷酸化的STAT3 / STAT3的表达水平被下调，而p53和p21则被上调。我们使用两步诱导法将pPSCs诱导至胰岛素分泌细胞，发现胰岛素分泌细胞中SerpinB1的表达高于pPSCs。同时，与对照细胞相比，诱导的胰岛素分泌细胞中磷酸化的STAT3 / STAT3的蛋白表达水平升高，而p53和p21降低。与对照组相比，源自sh-SerpinB1细胞的胰岛素分泌细胞分泌的胰岛素较少，并且对高葡萄糖的敏感性较差。然而，源自ov-SerpinB1细胞的胰岛素分泌细胞具有完全相反的趋势。综上所述，