Effect of hemX gene deletion on heme synthesis in Bacillus amyloliquefaciens / 生物工程学报

Heme, which exists widely in living organisms, is a porphyrin compound with a variety of physiological functions. Bacillus amyloliquefaciens is an important industrial strain with the characteristics of easy cultivation and strong ability for expression and secretion of proteins. In order to screen the optimal starting strain for heme synthesis, the laboratory preserved strains were screened with and without addition of 5-aminolevulinic acid (ALA). There was no significant difference in the heme production of strains BA, BAΔ6 and BAΔ6ΔsigF. However, upon addition of ALA, the heme titer and specific heme production of strain BAΔ6ΔsigF were the highest, reaching 200.77 μmol/L and 615.70 μmol/(L·g DCW), respectively. Subsequently, the hemX gene (encoding the cytochrome assembly protein HemX) of strain BAΔ6ΔsigF was knocked out to explore its role in heme synthesis. It was found that the fermentation broth of the knockout strain turned red, while the growth was not significantly affected. The highest ALA concentration in flask fermentation reached 82.13 mg/L at 12 h, which was slightly higher than that of the control 75.11 mg/L. When ALA was not added, the heme titer and specific heme production were 1.99 times and 1.45 times that of the control, respectively. After adding ALA, the heme titer and specific heme production were 2.08 times and 1.72 times higher than that of the control, respectively. Real-time quantitative fluorescent PCR showed that the expressions of hemA, hemL, hemB, hemC, hemD, and hemQ genes at transcription level were up-regulated. We demonstrated that deletion of hemX gene can improve the production of heme, which may facilitate future development of heme-producing strain.

Establishment of culture system for selective amplification of CD8+ T cells in vitro and analysis of its functional and molecular phenotypes from tumor-infiltrating lymphocytes in malignant pleural/ascites / 细胞与分子免疫学杂志

Objective To explore the culture method of mass amplification for tumor-infiltrating lymphocytes (TILs) from malignant pleural/ascites in vitro, and identify the function and molecular phenotype of these amplified cells. Methods The pleural/ascites fluid was extracted under aseptic conditions, and lymphocytes were isolated by density gradient centrifugation. Then TILs were amplified by the program based on combined IFN-γ, OKT3 and IL-2, and the cell morphology and growth rate were recorded. The molecular phenotypes of the amplified lymphocytes were analyzed by Flow cytometry, and the killing ability against tumor cells was detected by CCK-8 assay. Results In this culture program, TILs remained in good condition until the 26th day, and the proliferation rate began to decrease on the 30th day. The proportions of CD4-CD8+ and CD8+CD56+ T cells gradually increased as cell culture time extended while the proportions of CD4+CD25+ T cells decreased gradually. Unlike the proportions prior to amplification, the proportions of SLAMF7, CD45RO, PD-1 and granzyme B positive cells in T lymphocyte subpopulation were significantly increased, meanwhile, the expression of exhausted T-cell marker CD57 was also gradually increased. The cytotoxicity of amplified CD8+ T cells from TILs was significantly stronger than that from PBMC, and the cytotoxicity reached the peak at the effect-target ratio of 10:1 and was significantly different among tumor cell types. Conclusion A culture program for TILs amplification from cancerous thoracic/ascites is established. The method is simple and efficient. The effector cells are mainly CD8+ T lymphocytes with active phenotype.

Influence of stem-like cells on EMT occurrence in mice with triple-negative breast can-cer and on their biological behavior / 中国肿瘤临床

Objective:To discuss the influence of ALDH1+and CD133+phenotypic breast cancer stem-like cells in TA2 triple negative breast cancer on promoting epithelial-mesenchymal transition (EMT) occurrence in TA2 mice with triple-negative breast cancer and on their biological behavior. Methods:Flow cytometry was performed to analyze the markers ALDH1 and CD133 in TA2 mice triple nega-tive breast cancer and breast cancer stem-like cells with ALDH1+, ALDH1?, CD133+, and CD133?phenotypes, which were sorted out. Then, the TA2 mice were inoculated with sorted tumor cells according to cell type. The mice were divided into ALDH1+, ALDH1?, CD133+, and CD133-groups. The tumor-growing conditions were observed. A tumor tissue was sliced for the immunohistochemical testing of ALDH1?, CD133?, and EMT-related Twist1, E-cadherin, and VE-cadherin proteins. The expression difference of breast cancer stem cell surface markers ALDH1 and CD133 in triple-negative breast cancer and EMT-related proteins Twist1, E-cadherin, and VE-cad-herin was analyzed. Results:The expression rates of breast cancer stem cell markers ALDH1 and CD133 in TA2 mice triple negative breast cancer were 31.2%and 6.5%, respectively. The tumor growth ability of TA2 mice from ALDH1+group was obviously stronger than that from ALDH1?group. The CD133+group was evidently stronger than CD133?group. The immunohistochemical results showed that ALDH1, Twist1, and VE-cadherin expression levels in the ALDH1+group were evidently higher than that in the ALDH1?group (all P<0.05). E-cadherin expression decreased (P<0.05). CD133?, Twist1, and VE-cadherin expression levels in CD133+group were higher than that in CD133?group (all P<0.05). Conclusion:In TA2 mice triple negative breast cancer, ALDH1+and CD133+phenotypic breast cancer stem-like cells may influence the expression of EMT-related proteins, and promote the formation of triple-negative breast cancer.