EGFR upregulates inflammatory and proliferative responses in human lung adenocarcinoma cell line (A549), induced by lower dose of cadmium chloride

Abstract

Exposure to cadmium is associated with the development of pulmonary damage such as emphysema and lung cancer. This metal is also a powerful inducer of different proinflammatory and cell cycle regulatory proteins in many biologic models. Previously, we showed that prolonged exposure of low concentration of cadmium resulted in upregulation of proinflammatory cytokines and cell cycle regulatory molecules in mice lung cell. The present study was undertaken to determine molecular mechanism of inflammation and its relation to cell proliferation in a transformed human lung adenocarcinoma epithelial cell line (A549) in response to cadmium chloride. In comparative studies, we examine that short-duration exposure to lower doses of cadmium significantly increase the growth of A549 cells, whereas higher doses are toxic and cause cell death. We also observed that cadmium induced elevated expression of epidermal growth factor receptor (EGFR) along with different proinflammatory cytokines like interleukin-1 beta (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). The possible occurrence of cell proliferation events was evaluated via analysis of the physical state of the DNA and the expression of Ki-67 and proliferating cell nuclear antigen (PCNA). We also checked the pattern of expression of different cell cycle regulatory molecules involved in the onset of cell proliferation. Our results indicate that cadmium treatment appears to induce inflammatory and growth responses in transformed A549 cell line by activating EGFR and its downstream modulators. These results may contribute to better understand the toxic mechanism of cadmium; moreover, the expression profile of cadmium-induced regulatory molecules could provide potential biomarkers for cadmium exposure.

Keywords::

• EGFR
• A549 cell
• CyclinD1
• cytokine
• inflammation
• non-small cell lung carcinoma

Acknowledgments

Authors would like to thank Mr. Soumya Chatterjee, Mr Soham Mitra and Mr. Tarun Keswani for their continuous help in cell culture maintaining and ELISA assay and their guidance during cell preparation for cell cycle analysis. Authors would also like to thank Mr. Santanu Paul for his help during statistical analysis. Authors are very much grateful to Dr. Srikanta Chakraborty and Prof. A. Bhattacharyya of University Burdwan, West Bengal, India, for their unconditional help during SEM (scanning electron microscopy) analysis.

Declaration of interest

This work was supported by grants from Department of Science and Technology, Government of India (SR/FT/L-42/2006). The authors would also like to thank Department of Biotechnology, Government of India (BT/PR9779/GBD 27/67/2007) and Indian Council of Medical Research, Government of India (3/2/2/166–NCDIII, 2008) for equipment support.