The influence of interstitial brachytherapy with 125I seeds on Caspase-3 and Egr-1 expressions of Lewis lung carcinoma in C57BL mice

Abstract

ObjectiveThe aim of our study was to explore the influence of interstitial brachytherapy with 125I seeds on Caspase-3 and Egr-1 expressions
of Lewis lung carcinoma in C57BL mice.

MethodsModel mice of C57BL were planted with Lewis lung cells (LLC) and divided into the treatment group (n = 18) and the control group (n = 17). In each mouse of the treatment group, two BT-125-1 Model 125I seeds with apparent activity of 9.25 MBq were implanted into the tumor; whereas in each mouse of the control group two dummy
seeds were implanted. The mice survival rates of both groups were recorded after 21 days. The tumor weights and dimensions
of survived mice were measured, and the tumor volume inhibition rate was calculated. T-test was performed to compare differences
of tumor weights and volumes between these two groups. Routine pathological slides of tumor tissue were observed under light
microscope. The expression of Caspase-3 was detected by immunohistochemical method and the expression of Egr-1 was detected
by RT-PCR method.

ResultsThe survival rates were 88.88% in the treatment group and 70.59% in the control group, the difference had no statistical significance
(P > 0.05). The tumor volume inhibition rate was 71.12%. Pathological examination showed degeneration and necrosis of cancer
cells at the site nearby the seed in the treated group, but the tumor cells alive were still presented nearby the seed in
the control group. The expressions of Caspase-3 and Egr-1 in the treated group were higher than those in the control group
(t = 12.825, P < 0.01; t = 7.039, P < 0.01; respectively).

ConclusionThe interstitial brachytherapy with 125I seeds could significantly inhibit the growth of Lewis lung carcinoma of mice. The possible mechanism may be that 125I interstitial
brachytherapy can enhance the expressions of Egr-1 and Caspase-3, which could induce tumor cellular apoptosis.

Key words
125I seeds-interstitial brachytherapy-Lewis lung cell-Egr-1-Caspase-3