Targeting the EGF receptors on oral cancer cells with EGF. 46th Annual Meeting & Exhibition of the AADR

Objectives: The epidermal growth factor receptor (EGFR) may be useful in targeting oral squamous cell carcinoma (OSCC) cells to deliver suicide genes or photosensitizers. Using confocal microscopy, we investigated the binding of fluorescent EGF to the OSCC cell lines, HSC-3, CAL27 and H357 compared to non-tumor gingival epithelial cells (GECs) and GMSM-K, transformed human oral keratinocytes. Our long-term goal is to utilize EGF bound to liposomes encapsulating photosensitizers to target oral cancer cells for photodynamic therapy and potentially other anti-cancer therapies. Methods: HSC-3, CAL27 and H357 cells were seeded in 24-well culture plates on glass coverslips one day prior to incubation, at a density of 2.0 x 105 cells per well in 1 ml of DME medium containing 10% fetal bovine serum, 2 mM L-glutamine, and antibiotics. Non-tumor GECs and GMSM-K cells were seeded under the same conditions in keratinocyte serum-free medium supplemented with prequalified human recombinant EGF 1-53 and Bovine Pituitary Extract. Cells were incubated at 37 degrees Celsius under 5% CO2. Biotinylated EGF complexed to Alexa Fluor® 488 streptavidin was added at 1 µg/ml to the cells for 15 min to 1 h. Cells were then processed for imaging with a confocal microscope. Results: GECs and GMSM-K cells showed minimal EGF binding after 15 min compared to HSC-3, CAL27 and H357 cells, which showed high levels of EGF binding as observed by the green fluorescence on the cell surface. With longer incubations of up to 1 h, perinuclear localization of EGF in OSCC cell lines was observed. Conclusions: Selective toxicity to OSCC cells may be achieved by targeting liposomes to the EGFRs on these cells, since non-cancer cell lines appear to express significantly lower levels of EGFRs. Future studies will quantify bound EGF by flow cytometry, and the intracellular localization of EGF using fluorescent markers for organelles. Funded by Research Pilot Project Award DRES03-Activity 113 from the University of the Pacific, Arthur A. Dugoni School of Dentistry