Radiation sensitization by CAPE on human HeLa cells of cervical cancer

Abstract

Objective To study the radiosensitizing effect of caffic acid phenethyl ester （CAPE） on human cervical cancer HeLa cells. Methods MTT assay was used to measure the relation between the inhibition effect and CAPE concentrations by CAPE with different concentrations on HeLa ceils for 24 hours. HeLa cells were divided into the control and experimental groups, both of which were given 0, 2, 4, 6 and 8 Gy of ^60Co γ-irradiation, respectively. The cell clones were counted. Meanwhile HeLa cells were divided into the control, CAPE, irradiation and combination groups. Flow cytometric analysis was adopted to detect the changes of cell cycle distribution induced by CAPE. Results The inhibition rate of CAPE acting on Hela cells increased with concentrations（ F = 126.49 - 3654.88, P 〈 0.01 ）. HeLa cells cloning survival decreased with the increase of radiation dose（ F = 174.42 - 9422.81, P 〈 0.01 ）. At the same radiation dose, HeLa cells cloning survival was less in experimental group than control group（ F = 120.14 - 251.91, P 〈 0.01）. The mean lethal dose（ Do ） （1.45 and 1.82 Gy） and the quasi-threshold dose（ Dq ） （1.89 and 3.21 Gy） of HeLa cells in experimental group decreased comparing with control group, SER was 1.26. Compared with the sole irradiation group, cells in G2/M phase of the CAPE group and the sole irradiation group increased （P 〈 0.01 ） while the combination group decreased （ P 〈 0.01 ）. Conclusions CAPE could increase the radiation sensitivity of HeLa cells by G2/M arrest and may be related to the inhibition of the sub-lethal damage repair. Key words: Caffic acid phenethyl ester; Radiosensitizing effect; Cycle checkpoint; Ionizing radiation