9β,11β-Epoxypregn-4-ene-17α,21-diol-3,20-dione 21-acetate (Ⅰ) is a substrate for the production of 9β,11β-Epoxypregn-1,4-diene-17α,21-diol-3,20-dione (Ⅳ),which is a key precursor for the production of many 9-fluoro-substituted corticosteroid hormones.By comparing whole cells catalysis and cellular lysates conversion,it was found that whole cells of Mycobacterium sp.MS136 could only convert Ⅰ to 9β,11β-Epoxypregn-4-ene-17α,21-diol-3,20-dione (Ⅱ),and Ⅰ can be effectively converted toⅣ by cellular lysates.The reaction order is that Ⅰ is spontaneously hydrolyzed to Ⅱ and Ⅱ undergoes C1,2-dehydrogenation reaction to Ⅳ.In order to improve the productivity of Ⅳ,the key genes kstD,kstD3 and kstDM encoding C1,2-dehydrogenase (KSTD) were overexpressed in Mycobacterium sp.MS136 to enhance the C1,2-dehydrogenation reaction rate,and the results showed that 1 g/L substrate Ⅰ can be converted by recombinant strain MS136-kstDM cellular lysates at pH 7.0,the productivity of Ⅳ reached 78.4％ after 45 h,which is 38.9％ higher than original strain.The reaction rate is enhanced by optimizing the pH,and the results showed that 1 g/L substrate (Ⅰ) can be converted by recombinant strain MS136-kstDM cellular lysates at pH 7.5,the productivity of Ⅳreached 92.8％ after 45 h,which was 63.4％ higher than original strain.

CD47 is a transmembrane glycoprotein widely expressed on cells and an important signal molecule for immune escape of tumor cells. CD47, which is highly expressed in bladder cancer cells, can interact with signal regulatory proteins on the surface of macrophages- α (SIRPα). It combines and transmits immunosuppressive signals to protect tumor cells from phagocytosis, thereby mediating their immune escape. CD47-SIRPα signal pathways have become the focus of tumor cell immune checkpoint research at this stage. This article reviewed the research progress in the mechanism and clinical value of CD47 in bladder cancer.