IADR Abstract Archives
Protein Analysis of HNSCC Xenograft Tumors Following Blue Light Treatment
Objectives: Head and neck squamous cell carcinoma (HNSCC) makes up 90% of all oropharyngeal cancers. Treatments for these tumors include chemotherapy, radiation and surgery; however, high associated morbidity and mortality rates persist. Few new therapies have been developed in the past 30 years; therefore, innovative treatments are desperately needed. Our previous studies have shown that treatment of cultured HNSCC cells with 400-500 nm blue light (BL) can significantly reduce their viability as measured by WST assay. This study examined whether these effects can be reproduced in an in vivo model, and to begin to assess BL-induced changes in proteins relevant to tumor growth and progression.
Methods: UM-SCC-17B xenograft tumors harvested from nude mice (nu/nu) that were either untreated or treated daily with 90 sec exposures to blue light (45 J/cm2; 90 sec; Bisco VIP curing unit) were cut into equal pieces that were either formalin-fixed for immunohistochemistry or flash-frozen in liquid nitrogen for protein analysis. Tumor proteins (25 µg) were separated by 12% SDS-PAGE, transferred to PDVF membranes and exposed to antibodies specific for E-cadherin, IkappaB or β-actin as loading control.
Results: Over the 14 day treatment period, control tumors grew from an average of 47 mm3 to 114 mm3 (143% increase), while blue light-treated tumors grew from an average of 51 mm3 to 56 mm3 (9.8% increase). Total E-cadherin and IkappaB increased by ~260% and 200%, respectively, following light treatment.
Conclusions: Blue light treatment led to tumors that were significantly smaller in volume relative to control. In addition, blue light-induced increases in IkappaB and E-cadherin levels were observed. Increases in IkappaB may reduce NFkappaB’s anti-apoptotic and pro-proliferative effects, while increases in E-cadherin could promote cell adhesion and reduce tumor invasiveness. Further studies to investigate the mechanism for light-induced reduction in tumor growth are ongoing.
Methods: UM-SCC-17B xenograft tumors harvested from nude mice (nu/nu) that were either untreated or treated daily with 90 sec exposures to blue light (45 J/cm2; 90 sec; Bisco VIP curing unit) were cut into equal pieces that were either formalin-fixed for immunohistochemistry or flash-frozen in liquid nitrogen for protein analysis. Tumor proteins (25 µg) were separated by 12% SDS-PAGE, transferred to PDVF membranes and exposed to antibodies specific for E-cadherin, IkappaB or β-actin as loading control.
Results: Over the 14 day treatment period, control tumors grew from an average of 47 mm3 to 114 mm3 (143% increase), while blue light-treated tumors grew from an average of 51 mm3 to 56 mm3 (9.8% increase). Total E-cadherin and IkappaB increased by ~260% and 200%, respectively, following light treatment.
Conclusions: Blue light treatment led to tumors that were significantly smaller in volume relative to control. In addition, blue light-induced increases in IkappaB and E-cadherin levels were observed. Increases in IkappaB may reduce NFkappaB’s anti-apoptotic and pro-proliferative effects, while increases in E-cadherin could promote cell adhesion and reduce tumor invasiveness. Further studies to investigate the mechanism for light-induced reduction in tumor growth are ongoing.