CANSA Research

CANSA Research in Action Conference – July 2018 – Poster Session for Students – Flavia Zita Francies

CANSA Research in Action Conference – July 2018 – Poster Session for Students – Flavia Zita Francies

(Doctor of Philosophy – Completed)

Title of the type A grant: Genetic screening of triple negative and young breast patients in SA
Name of PI:  Prof Ans Baeyens

Abstract:

Ionising radiation versus mitomycin C induced chromosomal aberrations for Fanconi Anaemia diagnosis

Flavia Zita Francies1,2, Rosalind Wainwright3, Janet Poole4, J. P. Slabbert2, Ans Baeyens1,2,5

  1. Radiobiology, Department of Radiation Sciences, University of the Witwatersrand, Johannesburg, South Africa
  2. iThemba LABS – NRF, Somerset West, South Africa
  3. Department of Paediatrics, Chris Hani Baragwanath Academic Hospital and Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
  4. Department of Paediatrics, Charlotte Maxeke Johannesburg Academic Hospital and Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
  5. Radiobiology, Department of Basic Medical Sciences, Ghent University, Belgium

INTRODUCTION:

Fanconi Anaemia (FA) is an autosomal recessive disorder that is clinically characterised by congenital and developmental abnormalities, and haematological defects. FA is also defined by cellular hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC). Diagnosis of FA patients often includes detecting chromosomal aberrations induced by a cross-linking agent. FA patients are known to have defects with DNA repair and high risk to develop leukaemia and solid tumours that may require radiotherapy. FA patients undergoing radiotherapy have shown to display increased clinical radiosensitivity. Chromosomal radiosensitivity date of FA patients is very limited.

The aim of this study was to determine the chromosomal instability and radiosensitivity of FA patients and parents and compare it to controls using 3 different micronucleus (MN) assays.

METHODS:

In the G0 MN assay, heparinised blood in culture medium was irradiated at doses of 0, 2 and 4Gy with X-rays using a linear accelerator followed by the stimulation of lymphocytes using phytohaemagglutinin (PHA). Twenty three hours later, the cytoplasmic division was inhibited by the addition of cytochalasin B. Cells were harvested 70 hours post-irradiation and micronuclei were scored using the automated microscope, the Metafer MNScore Software (MetaSystems).

The S/G2 MN assay is a modified version of the G0 MN assay.
Heparinised blood and PHA are added to culture medium and incubated at 37°C for 72 hours. Cyto B was added immediately after irradiation. To detect DNA damage in the S/G2 phase of the cell cycle, the cells were harvested 8 hours post irradiation.

RESULTS:

The chromosomal instability was significantly elevated in FA patients when compared to FA parents and controls. Chromosomal radiosensitivity was also significantly elevated in FA patients. Chromosomal damage induced by MMC was also significantly higher in FA patients and parents compared to controls.

DISCUSSION:

Enhanced chromosomal instability and radiosensitivity is observed in FA patients. However, chromosomal radiosensitivity of FA patients is most prominent in the S/G2 phase. To distinguish FA patients from parents and controls, the MMC MN assay seemed to be the most sensitive assay.


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