Multifaceted p21 in carcinogenesis,stemness of tumor and tumor therapy

Cancer cells possess metabolic properties that are different from those of benign cells.p21,encoded by CDKN1A gene,also named p21Cip1/WAF1,was first identified as a cyclin-dependent kinase regulator that suppresses cell cycle G1/S phase and retinoblastoma protein phosphorylation.CDKN1A(p21)acts as the downstream target gene of TP53(p53),and its expression is induced by wild-type p53 and it is not associated with mutant p53.p21 has been characterized as a vital regulator that involves multiple cell functions,including G1/S cell cycle progression,cell growth,DNA damage,and cell stemness.In 1994,p21 was found as a tumor suppressor in brain,lung and colon cancer by targeting p53 and was associated with tumorigenesis and metastasis.Notably,p21 plays a significant role in tumor development through p53-dependent and p53-independent pathways.In addition,expression of p21 is closely related to the resting state or terminal differentiation of cells.p21 is also associated with cancer stem cells and acts as a biomarker for such cells.In cancer therapy,given the importance of p21 in regulating the G1/S and G2 check points,it is not surprising that p21 is implicated in response to many cancer treatments and p21 promotes the effect of oncolytic virotherapy.

O-glycosyltransferases from Homo sapiens contributes to the biosynthesis of Glycyrrhetic Acid 3-O-mono-β-D-glucuronide and Glycyrrhizin in Saccharomyces cerevisiae

Glycyrrhizin(GL)and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide(GAMG)are the typical triterpenoid glycosides found in the root of licorice,a popular medicinal plant that exhibits diverse physiological effects and pharmacological manifestations.However,only few reports are available on the glycosylation enzymes involved in the biosynthesis of these valuable compounds with low conversion yield so far.In mammals,glycosyltransferases are involved in the phase II metabolism and may provide new solutions for us to engineer microbial strains to produce high valued compounds due to the substrate promiscuity of these glycosyltransferases.In this study,we mined the genomic databases of mammals and evaluated 22 candidate genes of O-glycosyltransferases by analyzing their catalytic potential for O-glycosylation of the native substrate,glycyrrhetinic acid(GA)for its glycodiversification.Out of 22 selected glycosyltransferases,only UGT1A1 exhibited high catalytic performance for biosynthesis of the key licorice compounds GL and GAMG.Molecular docking results proposed that the enzymatic activity of UGT1A1 was likely owing to the stable hydrogen bonding interactions and favorite conformations between the amino acid residues around substrate channels(P82~R85)and substrates.Furthermore,the complete biosynthesis pathway of GL was reconstructed in Saccharomyces cerevisiae for the first time,resulting in the production of 5.98±0.47 mg/L and 2.31±0.21 mg/L of GL and GAMG,respectively.