Ball LM, Lannon CL, Yhap M, Pyesmany AF, Henry M, Laybolt K, Riddell DC, van Velzen D. PCNA bearing structures are retained in apoptotic phase of childhood ALL cell cycle.
ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1999;
457:289-96. [PMID:
10500804 DOI:
10.1007/978-1-4615-4811-9_31]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND
Drug resistance to DNA directed therapy may depend on proliferative as well as apoptotic cell fraction. PCNA/Ki67 ratio excess, possibly reflecting DNA excision repair, is of additional interest to drug resistance in MTT testing. The cell cycle phase/antigen expression pattern in childhood acute lymphoblastic leukemia (ALL) is not known.
AIMS
To study the relationship between nuclear expression of PCNA, Ki-67 and Frag-EL positivity in childhood ALL.
METHODS
1.3.1. Study Groups. Diagnostic bone marrow trephine biopsies of 32 consecutive unselected cases of childhood ALL were included in the study. 1.3.2. Immunohistochemistry. Commercially available Moab PCNA (PC10, DAKO, USA), Ki-67 (MM1, NovaCastra, UK) were used to label cycling cells in routinely processed 5 microns paraffin sections. 1.3.3. In-Situ Labelling of Apoptotic Cells. The 3'-OH ends of apoptosis specific DNA fragments were labelled in-situ on subsequent 10 microns sections (Frag-EL, CalBiochem, USA). 1.3.4. Quantitation. After blinding and randomisation, 10 systematic random fields of > 20 nuclei and nuclear size bias correction was used to determine positive nuclei fraction.
RESULTS
While the sum of apoptotic and proliferative cell fraction (Ki-67 + Frag-EL%) equalled 100% in 5/32 cases, PCNA expression into at least the early phases of apoptosis ([%PCNA-%K-67] > [100-%Frag-EL] was found in 17/32 cases.
CONCLUSIONS
PCNA/Ki67 ratio excess may not reflect DNA excision repair activity but rather slow degradation of antigen bearing structures limiting relevance to drug resistance study.
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