Novel strategy for the development of radioresistance breast cancer cell line

Madhu Leelavathi Narayana, Shama Rao, Sarojini Balladka Kunhanna


Purpose: Fractionated radiation dose therapy is a routine procedure for the breast cancer treatment. However, despite of continuous improvement, tumor recurrence occurs in high proportion of the patients. There is a need of suitable radioresistance cell line system to study the properties of tumor recurrence. But, developing a radioresistant cancer cell line is a time requiring process. It requires a multiple radiation dosages for a period of three to four months. The present study aims for the new strategy to develop a radioresistant breast cancer MCF-7 cell line.

Methods: The cells were exposed to 4Gy dosage of ϒ rays prior to 10Gy dose and subjected for clonogenic assay. The cells survived in the clonogenic assay were pooled and named as RR-MCF-7. These cells were subjected to Bcl-2 analysis, apoptotic assay and LDH assay.

Results: Developed cell line, RR-MCF-7 showed enhanced expression of Bcl-2 protein, which resulted in the declined apoptotic cell percentage. Though there was destabilization in the membrane of the irradiated cells, there was no significant difference observed in LDH level. Cloning efficiency of the 10 Gy exposed cells was found to be more when it was given a 4 Gy of prior dosage. The cells survived with this dosage showed the resistant character.

Conclusion: The approach followed in the current study for developing radioresistant cell line has reduced the time and dose requirement, also succeeded in obtaining resistant characters in it. 


Radioresistance, ϒ-radiation, Bcl-2, Breast cancer

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