Radiobiological Response of Cervical Cancer Cell Line in Low Dose Region: Evidence of Low Dose Hypersensitivity (HRS) and Induced Radioresistance (IRR).
BACKGROUND
Purpose of the present study was to examine the response of cervical cancer cell line (HeLa cell line) to low dose radiation using clonogenic assay and mathematical modeling of the low dose response by Joiner's induced repair model.


METHODS
Survival of HeLa cells following exposure to single and fractionated low doses of γ (gamma)-ray, 6 MV, and 15 MV photon was measured by clonogenic assay.


RESULTS
HeLa cell line demonstrated marked low dose response consisting of an area of HRS and IRR in the dose region of <1 Gy. The two gradients of the low dose region (αs and αr) were distinctly different with a transition dose (Dc) of 0.28-0.40 cGy.


CONCLUSIONS
HeLa cell line demonstrates marked HRS and IRR with distinct transition dose. This may form the biological basis of the clinical study to investigate the chemo potentiating effect of low dose radiation in cervical cancer.
Associate Professor, Department of Radiation Oncology, Christian Medical College Vellore, India .
Saikat
S
Das
Associate Professor, Department of Radiation Oncology, Christian Medical College Vellore, India .
Rabiraja
R
Singh
Medical Physics intern, Department of Radiation Oncology, Christian Medical College Vellore, India .
Daicy
D
George
Senior Scientist, Department of Nephrology, Christian Medical College Vellore, India .
T S
TS
Vijaykumar
Professor, Department of Radiation Oncology, Christian Medical College Vellore, India .
Subhashini
S
John
Clonogenic assay; HeLa cells; Radiotherapy