Squamous cell carcinoma of the head and neck (SCCHN) is a significant public health concern affecting over 50,000 patients annually in the US. Cisplatin-based chemoradiotherapy and cetuximab, an antibody targeting the epidermal growth factor receptor (EGFR), are standard treatments, but many patients eventually recur. Protein lysine methyltransferases (PKMTs) are a class of histone modifiers that are mostly known to regulate the histone epigenome through methylation of specific histone lysine residues. With the advent of the Cancer Genome Atlas (TCGA), PMTs were found to be mutated, amplified or overexpressed in SCCHN. More specifically, the PKMT WHSC1L1 was found to be among the top 10 most frequently amplified genes in SCCHN with a significantly recurrent amplification at the 8p11.23 region, where the gene is located, in approximately 10% of SCCHN tumors, implying its function as an oncogene. We have recently shown that WHSC1L1 promotes oncogenesis through induction of H3K36 di-methylation and transcriptional upregulation of the critical cell cycle regulators CDC6 and CDK2. Our findings also revealed that WHSC1L1 directly binds and mono-methylates nuclear EGFR, enhancing its interaction with proliferating cell nuclear antigen (PCNA) and promoting cell cycle progression in SCCHN cells. Despite the importance of WHSC1L1 in SCCHN oncogenesis, the genome-wide distribution of WHSC1L1 in head and neck cancer cells, the mechanisms that direct it to specific genomic loci, and the function of its interaction with nuclear EGFR are unknown. This project will elucidate the above questions by pursuing the following objectives:
Aim 1 : To determine the genome-wide distribution of WHSC1L1 in SCCHN cells and to assess whether the transcriptional regulation of its target genes is mediated through nuclear EGFR.
Aim 2 : To determine the mechanism through which WHSC1L1 interacts with EGFR to regulate the transcription of target genes in SCCHN cells. Major Activities: To answer the questions above, our experimental approach will include chromatin immunoprecipitation followed by DNA sequencing, RNA sequencing, and assessment of the kinetics of each of WHSC1L1 and nuclear EGFR through the use of single molecule tracking imaging technology in stably transfected SCCHN cell lines and CRISPR systems.
