Ferulic acid enhances the radiation sensitivity of lung and liver carcinoma cells by collapsing redox homeostasis: mechanistic involvement of Akt/p38 MAPK signalling pathway

Abstract

The major drawback of anticancer therapy is the development of resistance against drugs and radiation at the later phase of treatment which may lead to recurrences of the disease. Therefore, strategy was taken to enhance radiation sensitivity of lung (A549) and liver (HepG2) carcinoma cells by treatment with ferulic acid (FA) prior to irradiation. FA pre-treatment initially decreased reactive oxygen species (ROS) level in carcinoma cells which induced reductive stress and cytostasis. To overcome this stress, cellular mechanism increased the Keap1 level to down-regulate nuclear localisation of Nrf2 and its dependent antioxidant system. The antioxidant system reached the lowest level after 3 and 6 h of FA treatment in A549 and HepG2 cells respectively. As endogenous ROS were still being generated at same rate, ROS level was clearly higher than control which changed the reductive stress to oxidative stress. Exposure to γ-radiation in this condition further increased ROS level and caused radio-sensitisation of carcinoma cells. Combination of irradiation (IR) and FA activated mitochondrial apoptotic pathway and concomitantly inhibited the cell cycle progression and survival pathway over the IR group. Moreover, the combination treatment showed significant tumour regression, caspase 3 activation and nuclear fragmentation in tumour tissue compared to radiation alone. In contrast, FA pre-treatment protected peripheral blood mononuclear cells (PBMC) and normal lung fibroblast WI38 cells from radiation damage. Together, combination treatment offers effective strategy of killing cancer cells and demonstrates its potential for increasing the efficacy of radio-therapy.

Keywords:

• Carcinoma cells
• ferulic acid
• radiation sensitisation
• tumour regression
• γ-radiation

Acknowledgements

A Research Fellowship from CSIR-HRDG EMR-I, Govt. of India, to UD is gratefully acknowledged. We thank Dr Abhijit Saha and Dr Anindita Chakraborty for providing gamma radiation and flow cytometry facilities and other supports from UGC-DAE, CRS, Kolkata Centre. We deeply acknowledge Dr Suparna Banerjee, Ms Satabdi Ghosh and Dr Padmaparna Chaudhuri for their valuable inputs to improve the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

SD acknowledges the support of funding by University Grants Commission-Major project [41-3/2012.SR], Life Sciences Research Board [DLS/81/48222/LSRB-244/SH & DD/2012], Council of Scientific & Industrial Research [23(0024)/12/EMR-II], Coconut Development Board [1345/20011-Tech] and West Bengal DBT [593-BT(Estt)/RD-9/11]. SD acknowledges the support of Department of Science and Technology (DST) for PURSE scheme to the Department of Physiology and UGC, Government India for support under CPEPA scheme granted to University of Calcutta.