BioProject

Combination of platinum-based chemotherapy and radiation is currently the standard treatment for locally advanced lung cancer patients. However, therapeutic resistance to these therapies may arise from the presence of cancer stem cells (CSCs). To investigate the CSCs hypothesis of chemo-radiation resistance, we used microarray assay to profile CSCs-like cisplatin-resistant lung cancer cells (CDDP-R) versus its parental cells. CDDP-R cells were established by exposing H460 lung cancer cells to 3µM cisplatin for 7 days, followed by 0.8% methylcellulose selection over 14 consecutive days. We found that CDDP-R cells expressed higher levels of stem cell markers, including CD133 and ALDH. They are more resistant to cisplatin- and etoposide-induced apoptosis and to high radiation dose (20Gy). Clonogenic assays suggest that CDDP-R cells were more resistant to radiation than parental H460 cells (DER=1.21, p<0.01). Xenograft studies suggest that CDDP-R cells were more tumorigenic (p<0.001). Microarray and comprehensive protein interaction networks analyses revealed IGFBP3 as a highly ranked hub protein which plays an important role in the mechanism of cisplatin resistance. We found reduced level of IGFBP3 and enhanced IGFR-1 activation upon IGF stimulation in CDDP-R cells. The specific targeting of IGF-1R using siRNA resulted in significant sensitization of CDDP-cells (DER=1.17, p<0.05) to radiation compared with the parental H460 cells. Our findings suggest that CDDP-R cells have the characteristics of CSCs and constitute a “suitable” model to study lung CSCs. Profiling of CSCs-like H460 cells led to the identification of IGF as an important pathway for chemo- and radiotherapy resistance in lung cancer. Overall design: gene expression comparison of two groups