IADR Abstract Archives
Novel Combination Treatment for Oral Squamous Cell Carcinoma (OSCC)
Objectives: Fendiline, an approved anti-anginal drug, is a strong candidate as a therapeutic agent for treatment of OSCC as it indirectly targets EGFR signaling, which plays a large role in tumorigenesis and metastasis. Using non-human MDCK and CHO cell lines, it was previously shown that fendiline depletes plasma membrane cholesterol, and thereby induces EGFR mislocalization. Consequently, in OSCC cell lines overexpressing EGFR, fendiline inhibits downstream signaling, proliferation, and clonogenic survival. Goals of this study were to evaluate the efficacy of fendiline in vitro in combination with clinically used EGFR inhibitor erlotinib, and test the hypothesis that Drosophila is an appropriate model to examine whether fendiline mislocalizes cholesterol and inhibits EGFR in a whole organism.
Methods: Two EGFR over-expressing OSCC cell lines were used in in vitro assays. In clonogenic survival assays, cells were seeded in 6-well plates, treated with drugs for 2-3 weeks, fixed and stained with crystal violet. In proliferation assays, cells were seeded in 96-well plates, treated with drugs for 48 hrs and counted. In the Drosophila experiments, flies expressing mCherry-tagged cholesterol probe D4H were treated with trehalose (control) or fendiline for 3 days before dissecting larval salivary glands for imaging using confocal microscopy.
Results: Fendiline concentration-dependently increases the efficacy of erlotinib to inhibit clonogenic survival compared to erlotinib alone. Similarly, dose-response curves of erlotinib with or without fendiline show that a combination of fendiline with low nM concentrations of erlotinib can as efficaciously inhibit proliferation of OSCC cells as 30 µM erlotinib alone. In Drosophila salivary glands, intracellular cholesterol-laden vesicles observed in control specimens were decreased in fendiline-fed flies, suggesting that cholesterol organization is altered by fendiline in vivo.
Conclusions: Fendiline used in combination with erlotinib is more effective at inhibiting proliferation and clonogenicity than erlotinib alone. Drosophila can be used a model system to study fendiline-mediated effects in vivo.
Methods: Two EGFR over-expressing OSCC cell lines were used in in vitro assays. In clonogenic survival assays, cells were seeded in 6-well plates, treated with drugs for 2-3 weeks, fixed and stained with crystal violet. In proliferation assays, cells were seeded in 96-well plates, treated with drugs for 48 hrs and counted. In the Drosophila experiments, flies expressing mCherry-tagged cholesterol probe D4H were treated with trehalose (control) or fendiline for 3 days before dissecting larval salivary glands for imaging using confocal microscopy.
Results: Fendiline concentration-dependently increases the efficacy of erlotinib to inhibit clonogenic survival compared to erlotinib alone. Similarly, dose-response curves of erlotinib with or without fendiline show that a combination of fendiline with low nM concentrations of erlotinib can as efficaciously inhibit proliferation of OSCC cells as 30 µM erlotinib alone. In Drosophila salivary glands, intracellular cholesterol-laden vesicles observed in control specimens were decreased in fendiline-fed flies, suggesting that cholesterol organization is altered by fendiline in vivo.
Conclusions: Fendiline used in combination with erlotinib is more effective at inhibiting proliferation and clonogenicity than erlotinib alone. Drosophila can be used a model system to study fendiline-mediated effects in vivo.