On Predictive Factors of Treatment Response in Head and Neck Squamous Cell Carcinoma

Abstract: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer and yearly include 500 000 new cases worldwide. The outcomes for these patients have not been significantly improved over the last decades and the five year survival is still around 50 %. Establishing predictive markers of treatment response will have great impact on the clinical management of this disease.The aim of this thesis was to elucidate markers of intrinsic response to radiotherapy and cisplatin. Combining expression patterns of 14 proteins and identifying mutations in the p53 gene, we were able to incorporate both protein and genetic changes to create a predictive model termed Number of Negative Points (NNP). We used the NNP model to statistically calculate the combination of factors that had the best correlation to intrinsic radiosensitivity (IR). We established that a panel of three markers, epidermal growth factor receptor (EGFR), survivin and splice site/missence mutations of p53, had the best correlation to IR (R=0.990, p<0.0001).We also conducted gene expression analysis to investigate what genes and gene ontologies that are different between cell lines with varying IR. Furthermore, we wanted to identify key regulator genes with central positions of molecular networks, which were generated from the transcripts included in the deregulated gene ontologies. A transcriptional profile of 28 key regulator genes was generated. Immunoblot analysis supported deregulation at the protein level of three markers implicated from the transcriptional profile. We propose that these proteins, notch1, thrombospondin 1, and pai‐1 are predictive markers of IR.Finally, on a subset of cell lines with sensitivity or resistance to cisplatin, we performed gene expression analysis. Markers of intrinsic cisplatin sensitivity (ICS) such as gene ontologies and key regulators of molecular networks were proposed and five genes, APOE, CTNNB1, MMP7, MMP13, and THBS1 were selected for further analysis. Quantitative polymerase chain reaction (qPCR) analysis of these genes in 25 cell lines established that MMP7 (p=0.0013) and MMP13 (p=0.058) are possible predictive markers of ICS.The markers of IR and ICS presented here could, if confirmed in a clinical setting, guide clinicians in the choice of treatment and thus give a more individualized and effective therapy for patients with HNSCC.