The trehalose synthase (ScTreS) gene from Streptomyces coelicolor was successfully cloned and heterologously expressed in Escherichia coli BL21(DE3). The protein purified by Ni-NTA affinity column showed an apparent molecular weight (MW) of 62.3 kDa analyzed by SDS-PAGE. The optimum temperature of the enzyme was 35 °C and the optimum pH was 7.0; the enzyme was sensitive to acidic conditions. By homologous modeling and sequence alignment, the enzyme was modified by site-directed mutagenesis. The relative activities of the mutant enzymes K246A and A165T were 1.43 and 1.39 times that of the wild type, an increased conversion rate of 14% and 10% respectively. To optimize the synthesis conditions of trehalose, the mutant strain K246A was cultivated in a 5-L fermentor and used for whole-cell transformation. The results showed that with the substrate maltose concentration of 300 g/L at 35 °C and pH 7.0, the highest conversion rate reached 71.3%, and the yield of trehalose was 213.93 g/L. However, when maltose concentration was increased to 700 g/L, the yield of trehalose can reach 465.98 g/L with a conversion rate of 66%.
Biocatalysis ; Cloning, Molecular ; Escherichia coli ; Glucosyltransferases ; Streptomyces coelicolor ; Trehalose

Owing to incurable castration-resistant prostate cancer (CRPC) ultimately developing after treating with androgen deprivation therapy (ADT), it is vital to devise new therapeutic strategies to treat CRPC. Treatments that target programmed cell death protein 1 (PD-1) and programmed death ligand-1 (PD-L1) have been approved for human cancers with clinical benefit. However, many patients, especially prostate cancer, fail to respond to anti-PD-1/PD-L1 treatment, so it is an urgent need to seek a support strategy for improving the traditional PD-1/PD-L1 targeting immunotherapy. In the present study, analyzing the data from our prostate cancer tissue microarray, we found that PD-L1 expression was positively correlated with the expression of heterogeneous nuclear ribonucleoprotein L (HnRNP L). Hence, we further investigated the potential role of HnRNP L on the PD-L1 expression, the sensitivity of cancer cells to T-cell killing and the synergistic effect with anti-PD-1 therapy in CRPC. Indeed, HnRNP L knockdown effectively decreased PD-L1 expression and recovered the sensitivity of cancer cells to T-cell killing in vitro and in vivo, on the contrary, HnRNP L overexpression led to the opposite effect in CRPC cells. In addition, consistent with the previous study, we revealed that ferroptosis played a critical role in T-cell-induced cancer cell death, and HnRNP L promoted the cancer immune escape partly through targeting YY1/PD-L1 axis and inhibiting ferroptosis in CRPC cells. Furthermore, HnRNP L knockdown enhanced antitumor immunity by recruiting infiltrating CD8⁺ T cells and synergized with anti-PD-1 therapy in CRPC tumors. This study provided biological evidence that HnRNP L knockdown might be a novel therapeutic agent in PD-L1/PD-1 blockade strategy that enhanced anti-tumor immune response in CRPC.

Objective:The aim of this retrospective study is to evaluate the safety and efficacy of tislelizumab in patients with recurrent/metastatic head and neck squamous cell carcinoma. Methods:Six patients with recurrent/metastatic head and neck squamous cell carcinoma who received tislelizumab monotherapy in our hospital from 2018 to 2020 were retrospectively analyzed. The information of sex, age, TNM stage, efficacy, and adverse reactions were collected. All patients were recruited from the RATIONALE 102 study. The primary end point was the objective response rate, and other end points included progression-free survival and overall survival. We performed tumor immune-related gene sequencing and transcriptome sequencing analysis on the tumor tissues of the patient, and used bioinformatics methods to enrich immune cells and analyze signaling pathways. All analyses were performed using R 4.1. 0 software, SPSS Statistics 24.0 software and GraphPad Prism 8. Results:As of May 31, 2020, the median follow-up time was 26.35 months. The objective response rate with tislelizumab was 50.0%, the median progression-free survival was 6.44 months, and the estimated median survival was 20.07 months. The incidence of grade 3 or higher adverse reactions was 66.7%, including hyponatremia, hypokalemia, hypercalcemia, etc. The expression of macrophage, Treg and neutrophil-related genes are higher in immune-sensitive patients, and the signaling pathways of the intestinal immune network for IgA production, graft versus host disease and autoimmune thyroid disease are significantly activated. Conclusion:Tislelizumab was found to be controllable and tolerable in patients with recurrent/metastatic head and neck squamous cell carcinoma. The response to tislelizumab is related to immune cell infiltration and activation of immune-related signaling pathways.
Humans ; Squamous Cell Carcinoma of Head and Neck/etiology* ; Retrospective Studies ; Carcinoma, Squamous Cell/pathology* ; Neoplasm Recurrence, Local/pathology* ; Head and Neck Neoplasms ; Antineoplastic Combined Chemotherapy Protocols