Decitabine is an azanucleoside (AZN), a pyrimidine analogue of cytidine
. Cancer cells often exhibit severely altered chromatin structure and methylation patterns leading to promoter hypermethylation and silencing of key tumor suppressor genes.
Niedobitek, "Activation-induced cytidine
deaminase (AID) is expressed in normal spermatogenesis but only infrequently in testicular germ cell tumours," Journal of Pathology, vol.
Blomberg, "Reduced Ig class switch in aged mice correlates with decreased E47 and activation-induced cytidine
deaminase," Journal of Immunology, vol.
Jankovic et al., "MicroRNA155 suppresses activation-induced cytidine
deaminase-mediated Myc-Igh translocation," Immunity, vol.
Abbreviations: AID: activation-induced cytidine
deaminase; ASPP2: apoptosis-stimulating protein of p53 2; CagA: Cytotoxin-associated gene A; CBS: C-terminal binding sequence; CM: CagA multimerization; [CM.sup.AmI]: Amerindian type-I CM; [CM.sup.AmII]: Amerindian type-II CM; [CM.sup.E]: East Asian CM; [CM.sup.W]: Western CM; CSK: C-terminal Src kinase; EBV: Epstein-Barr virus; EMT: epithelial-to-mesenchymal transition; EPIYA: GluPro-Ile-Tyr-Ala; GAB: Grb2-associated binder; H.
(4) Immunoglobulin diversification based on the "somatic hypermutation" (SHM) process, which is regulated by the MutS[alpha]-MutL[alpha] complex, in combination with two other proteins, AID (activation-induced cytidine
deaminase) and Pol[mu] (DNA Polymerase "error-prone") ; in particular, MutSa deficiency is associated with neoplastic transformation of T lymphocytes 
, 5-methylcytidine, BIS-TRIS propane, tris(hydroxymethyl)aminomethane (TRIS), [H.sub.3]P[O.sub.4], HCl, formic acid, acetonitrile, and deoxyribonucleic acid from calf thymus were purchased from Sigma-Aldrich, Italia (Milan, Italy).
It is also interesting to note that EBV infection of B cells upregulates the expression of enzymes like cytidine
deaminase expression, an essential mediator in the process of somatic hypermutation .
Therefore, although these agents have been known for a long time, only two inhibitors of DNA methyltransferases, 5-azacytidine (Vidaza) and 5-aza-2-deoxycytidine (decitabine), a cytidine
analog, with better specificity, remarkable inhibition of DNA methylation, and less toxic effects than 5-azacytidine, have already been approved by the FDA as effective drugs for treatment of myelodysplastic syndromes [12, 113].
Meanwhile, all patients received nasal tube of oxygen inhalation and conventional treatment with regulating water and electrolytes, maintaining stable blood pressure and blood glucose, and injecting cytidine
diphosphate choline (CDPC) and vitamin B.
To date, more than 10 nucleosides, nucleobases, and their related compounds including adenine, adenosine, cytosine, cytidine
, uridine, guanine, guanosine, hypoxanthine, vernine, thymidine, cordycepin, and 2',-deoxyuridine have been isolated from O.
Michelessi et al., "Cytidine
51-diphosphocholine (Citicoline) in glaucoma: Rationale of its use, current evidence and future perspectives," International Journal of Molecular Sciences, vol.