Using micronuclei assay in cancer treatment
Ghazaleh Kamrani,
1,*
1. National Institute of Genetic Engineering and Biotechnology
Abstract
Introduction
Cancer is one of the leading causes of illness and mortality worldwide, after cardiovascular disease. there are different ways to treat cancer, the most common being chemotherapy and radiotherapy. however, these treatments are not without long term side effects. both treatments can cause some mutations in the dna of a healthy cell leading – sometimes- to incidence of secondary cancer. some dna mutations with base damages and single strand breaks of dna, can be repaired in a normal cell, however, the repair system is not responsive to all of the cell damages, like double strand breaks in the dna. many of these damages can appear as chromosomal aberrations.
during the mitosis in a cell, affected by chromosome break, a small part of the chromatin cannot join the daughter nuclei and after telophase, the nucleus membrane, in addition to forming around the daughter nuclei will form around these small parts of the chromosome. these bodies are smaller than the main nucleus and are called micronuclei (mn).
the objective of this research is to study the micronuclei creation in the peripheral blood lymphocytes of cancer patients and to use this information to improve the therapeutic process. an increased micronuclei frequency in peripheral blood lymphocytes is a reflection of dna damage rate in the cell and chemotherapy or radiotherapy treatment can cause dna aberrations and lead to the secondary cancer.
Methods
The blood samples of 25 cancer patients were extracted and cultured into a complete culture medium (fbs 10%), with 200 microliters of pha, for 44-45 hours in the 37̊ incubator. then, 50 microliters of cytochalasin-b were added and the samples were left in the incubator for 72 hours after the culture. after that, cells were taken to the harvesting stage of the test.
during this research, 1000 bi-nucleated cells were counted in each sample by microscope and the amount of mn were analysed.
Results
The average numbers of micronuclei, before and after treatment, was 310.76 with a standard deviation of 76.44 in 1000 lymphocytes. also, the average survival rate was 13.56 months with a standard deviation of 2.21 months. it is also understood that patient's gender and age did not have a significant effect on mn frequency and life expectancy. (p<0.05)
Conclusion
As a result of cell counting we noted an increase in mn frequency after treatmentt, demonstrating the disadvantageous effects of these treatments on cancer patients.
such effects have been mentioned in previous studies, such as nachtab et al. nachtab et al showed that an increase in mn frequency is the result of acute complications after radiotherapy. also, the complications after chemotherapy is related to mn frequency in patient peripheral blood lymphocytes.
one of the cancer incidence factors is the increase of chromosome sensitivity to radiation and chemical agents. one of these increased sensitivities is defectiveness of dna repair genes that can lead to mn formation in the cell.
the risk of cancer incidence is higher in people with higher than average rate of mn frequency in their peripheral blood lymphocytes. thus, applying a method which uses mn frequency to help the treatment process and reducing the treatment-caused damages, such as cytogenetic tests, is very important and could be a major aid in development of personalised medicine.
this research shows that mn frequency has increased significantly after treatment. also, it is noticeable from the results that the survival rate in different age and gender groups are under the influence of mn frequency; as the mn amount increases, the patient's life expectancy decreases.
Keywords
Micronuclei- lymphocyte- peripheral blood- gastric cancer- chemotherapy.
