title: Proof of differentiative mode of action of all-trans retinoic acid in acute promyelocytic leukemia using X-linked clonal analysis.
abstract: Using X-linked clonal analysis, mechanism of action of all-trans retinoic acid (ATRA) was sought in a 16-year-old female with relapsed clonally evolved acute promyelocytic leukemia (APL), who achieved complete remission. On ATRA, metamorphosis of peripheral blood leukemic promyelocytes to mature neutrophils was observed, despite the persistence of t(15;17) in 100% of bone marrow metaphases. DNA was extracted from fractionated serial blood specimens, collected at diagnosis, in first complete remission (CR), relapse, and during ATRA treatment. Using a phosphoglycerokinase (PGK) probe, the patient was heterozygous for both Bgl I and Bst XI PGK polymorphisms. Methylation analysis showed monoclonal leukemic promyelocytes with a polyclonal first CR achieved by standard chemotherapy. Subsequent examination, in relapse, of granulocytes appearing during ATRA treatment showed these to be monoclonal, proving these were derived from the neoplastic clone. The X-linked clonal analysis methodology has provided in vivo evidence of cellular differentiation as the mechanism of action of ATRA. Parallel studies of cytogenetic and clonal analysis showed a regression of the t(15;17) cytogenetic abnormality and return of a polyclonal PGK methylation pattern in 5 weeks, indicating a repopulation of marrow by normal stem cells. As standard cytogenetic techniques are inappropriate for nondividing cells, X-linked clonal analysis provides a marker system to allow insight into mechanism of drug action in malignant hematologic disease.
authors.affiliation: Hematology Department, Mater Misericordiae Hospital, South Brisbane, Queensland, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Elliott
authors.forename: K
authors.initials: K
authors.lastname: Taylor
authors.forename: S
authors.initials: S
authors.lastname: White
authors.forename: R
authors.initials: R
authors.lastname: Rodwell
authors.forename: P
authors.initials: P
authors.lastname: Marlton
authors.forename: D
authors.initials: D
authors.lastname: Meagher
authors.forename: J
authors.initials: J
authors.lastname: Wiley
authors.forename: D
authors.initials: D
authors.lastname: Taylor
authors.forename: S
authors.initials: S
authors.lastname: Wright
authors.forename: P
authors.initials: P
authors.lastname: Timms
mesh_terms: D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015139:Blotting, Southern; D001853:Bone Marrow / Q000473:pathology; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002884:Chromosomes, Human, Pair 15; D002886:Chromosomes, Human, Pair 17; D002999:Clone Cells; D003561:Cytarabine / Q000008:administration & dosage; D004273:DNA, Neoplasm / Q000235:genetics; D003630:Daunorubicin / Q000008:administration & dosage; D005047:Etoposide / Q000627:therapeutic use; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D014178:Translocation, Genetic; D014212:Tretinoin / Q000627:therapeutic use*; D014960:X Chromosome
chemical_list: D004273:DNA, Neoplasm; D003561:Cytarabine; D014212:Tretinoin; D005047:Etoposide; D003630:Daunorubicin