Abstract A08: Cancer stem cell-like cells in drug resistance of head and neck squamous cell carcinoma
Authors: Kulsum Safeena , VG Sindhu , Pandian Ramanan Somasundara , Das Debashish , Panda Binay , Hicks Wesley , Seshadri Mukund , Kuriakose Moni Abraham , Suresh Amritha 
Published: May 2015

Abstract
This study attempts to evaluate the correlation between cancer stem cell (CSC) like-cells and drug resistance in Head and Neck Squamous Cell Carcinoma. Single and triple resistant sub-lines of CAL-27 and HEp-2 cells developed in the lab were used to correlate increased prevalence of stem cell-like cells with drug resistance.The drug resistant sublines were initially evaluated for their resistance by MTT assay, apoptosis assay and expression of drug resistance genes. They were subsequently evaluated for expression of stemness specific genes (CD44, CD133, ALDHA1, ABCG2, BMi1, SOX-2, NOTCH, NANOG, and OCT-4) using Quantitative real-time PCR (QRT-PCR). Increased self-renewal, migration and tumorigenic property of these cells were assessed using spheroid formation, clonogenic survival, wound healing and tumorigenicity assays. Transcriptome sequencing is currently going on to profile the drug resistant cancer stem cell properties. Stemness specific genes were also validated using in normal, primary and recurrent patient samples using QRT-PCR. Assessment of the four drug resistant head and neck cancer sub-lines (CAL-27CisR, HEp-2CisR, CAL-27 TPFR and HEp-2 TPFR) by MTT assay revealed an increase in the IC50 values (RI &gt;3) in a three independent experiments (* p&lt;0.05). Apoptosis assay also showed an increased resistance to apoptosis while expression profiling indicated a significant up regulation of all the resistant genes (MDR1, MRP2, Survivin, ERCC1 and CTR1). Quantitative expression profiling of resistant cells showed an up-regulation of genes characterizing stem-cell like properties. Cell cycle analysis showed a decreased percentage of cells in the G1/G0 and an increased presence in G2/M in cisplatin resistant cells and the TPFR cell lines in a three independent experiments (* p&lt;0.05). Functional assays indicated an increased spheroid formation, colony formation and increased migration properties in TPFR resistant cell lines as compared to the parental counterparts. Similar studies are ongoing in the cisplatin resistant cell lines to evaluate their functional properties. Validation in patient sample also showed an increase in stemness gene expression in recurrent patients. This study indicates that the resistant sub-lines of HNSCC cells showed an enrichment of cancer stem cell-like cells. Further studies in this direction are warranted towards delineating the molecular and cellular basis of this association
Citation Format: Safeena Kulsum, Sindhu VG, Ramanan Somasundara Pandian, Debashish Das, Binay Panda, Wesley Hicks, Mukund Seshadri, Moni Abraham Kuriakose, Amritha Suresh. Cancer stem cell-like cells in drug resistance of head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A08.