Association of Elevated Peripheral Blood Micronucleus Frequency and Bmi-1 mRNA Expression with Metastasis in Iranian Breast Cancer Patients

Document Type: Research Articles


Department of Medical Genetics, Institute of Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran.


Background: In order to find cytogenetic and molecular metastasis biomarkers detectable in peripheral blood the
spontaneous genomic instability expressed as micronuclei and Bmi-1 expression in peripheral blood of breast cancer
(BC) patients were studied in different stages of the disease compared with unaffected first-degree relatives (FDRs)
and normal control. Methods: The Cytokinesis Block Micronuclei Cytome (CBMN cyt) and nested real-time Reverse
Transcription-Polymerase Chain Reaction (RT-PCR) assays, were respectively used to measure genomic instability and
Bmi-1 gene expression in 160 Iranian individuals comprised of BC patients in different stages of the disease, unaffected
FDRs and normal control groups. Result: The frequency of micronuclei and Bmi-1 expression were dramatically higher
in distant metastasis compared with non-metastatic BC. In spite of micronucleus frequency with no association with
lymph node (LN) involvement and hormone receptor status, the Bmi-1 expression level was higher in LN positive and
triple negative patients. Conclusion: Our results indicate that increased genomic instability expressed as micronuclei and
higher Bmi-1 expression in peripheral blood are associated with metastasis in breast cancer. Therefore implementation
of micronucleus assay and Bmi-1 expression analysis in blood as possible cytogenetic and molecular biomarkers in
clinical level may potentially enhance the quality of management of patients with breast cancer.


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