Transcriptome Analysis Reveals the Role of Sucrose in the Production of Latilactobacillus sakei L3 Exopolysaccharide.

Latilactobacillus (L.) sakei is a species of lactic acid bacteria (LAB) mostly studied according to its application in food fermentation. Previously, L. sakei L3 was isolated by our laboratory and possessed the capability of high exopolysaccharide (EPS) yield during sucrose-added fermentation. However, the understanding of sucrose promoting EPS production is still limited. Here, we analyzed the growth characteristics of L. sakei L3 and alterations of its transcriptional profiles during sucrose-added fermentation. The results showed that L. sakei L3 could survive between pH 4.0 and pH 9.0, tolerant to NaCl (<10%, w/v) and urea (<6%, w/v). Meanwhile, transcriptomic analysis showed that a total of 426 differentially expressed genes and eight non-coding RNAs were identified. Genes associated with sucrose metabolism were significantly induced, so L. sakei L3 increased the utilization of sucrose to produce EPS, while genes related to uridine monophosphate (UMP), fatty acids and folate synthetic pathways were significantly inhibited, indicating that L. sakei L3 decreased self-growth, substance and energy metabolism to satisfy EPS production. Overall, transcriptome analysis provided valuable insights into the mechanisms by which L. sakei L3 utilizes sucrose for EPS biosynthesis. The study provided a theoretical foundation for the further application of functional EPS in the food industry.

A Dual Bispecific Hydrolysis Peptide-Drug Conjugate Responsive to Micro-Acidic and Reduction Circumstance Promotes Antitumor Efficacy in Triple-Negative Breast Cancer.

Paclitaxel and its derivates are the first-line chemotherapeutic agents of breast cancer, which also showed tremendous clinical value in many other diseases including ovarian cancer, lung cancer etc. However, there are many drawbacks for almost all paclitaxel or its derivates, including extremely short half-life, poor solubility and adverse events, which significantly limits their clinical applications. In this work, we designed and constructed a bispecific hydrolysis PAP-SS-PTX (term as PDC), consisting with pro-apoptosis peptide (PAP) and paclitaxel (PTX) that were conjugated together via disulfide and ester bonds. On the one hand, PAP could improve the solubility of PTX and promote cellular uptake for drugs. On the other hand, it was able to prolong the PTX half-life. We performed series of chemo-dynamical assays and showed that PDC would release active drug molecules under micro-acidic and reduction circumstance. The further assays elucidated that PDC could interrupt DNA synthesis and arrest cell division through downregulating CDK4/6 and Histone methylation that inhibit tumor growth in vitro. What's more, it could not only inhibit 4T1 breast tumor growth, but also prolong the survival time of mice and exert antitumor efficacy in vivo. It may provide a new research idea for cancer therapies via controlled release strategy in tumor microenvironment.