Delivery Of O6-Benzylguanine And Caffeine Via Ph-Responsive, Fusogenic Liposomes Into Brain Tumor Cell Lines

Crystal Carpenter

School Name

Governor's School for Science and Math

Grade Level

12th Grade

Presentation Topic

Cell and Molecular Biology

Presentation Type

Mentored

Mentor

Mentor: Dr. Broome; Department of Radiology and Radiological Science, Medical University of South Carolina

Written Paper Award

4th Place

Abstract

Glioblastoma are incurable brain tumors that contribute to 40-67% of primary brain tumors. The current treatment for glioblastoma is temozolomide which prevents replication of glioblastoma DNA. Delivery of chemotherapy drugs to glioblastoma is an issue because of rejection by the immune system due to the blood-brain barrier along with the buildup of resistant tumor cells due to expression of methylguanine DNA methyl transferase (MGMT), an enzyme that repairs DNA. The aim of this research is to create novel fusogenic, pH-responsive liposomes containing either O6-benzylguanine, an MGMT inhibitor, and/or caffeine, a natural stimulatory compound, which can be delivered and internalized into brain tumor cell lines. The liposomes were self-assembled with caffeine or O6-benzylguanine and four varieties of lipids and tagged with Dylite 755 and Dylite 680. These liposomes were then sized through UV-Visible spectroscopy, Dynamic Light Scattering indicated fluorophore attachment, and zeta potential analysis indicated charge of the liposomes. Two glioblastoma lines, U87 MG (MGMT-) and LN229 (MGMT+), were cultured on coverslips overnight and treated with 0.5 µM of O6-benzylguanine liposomes for various time points up to twenty-four hours, and this was repeated with 0.5 µM of caffeine only and 0.5 µM of both caffeine/O6-benzylguanine. Fluorescence microscopy of the slides showed an increase in uptake with time. Quantitative analysis showed that LN229 cells are more efficient in uptake than U87 MG cells. Results also indicated that the larger, more negative liposomes had less cellular uptake. Potential future directions include a pH-stability assay and varying the concentration of liposomes.

Location

Owens 201

Start Date

4-16-2016 9:15 AM

COinS
 
Apr 16th, 9:15 AM

Delivery Of O6-Benzylguanine And Caffeine Via Ph-Responsive, Fusogenic Liposomes Into Brain Tumor Cell Lines

Owens 201

Glioblastoma are incurable brain tumors that contribute to 40-67% of primary brain tumors. The current treatment for glioblastoma is temozolomide which prevents replication of glioblastoma DNA. Delivery of chemotherapy drugs to glioblastoma is an issue because of rejection by the immune system due to the blood-brain barrier along with the buildup of resistant tumor cells due to expression of methylguanine DNA methyl transferase (MGMT), an enzyme that repairs DNA. The aim of this research is to create novel fusogenic, pH-responsive liposomes containing either O6-benzylguanine, an MGMT inhibitor, and/or caffeine, a natural stimulatory compound, which can be delivered and internalized into brain tumor cell lines. The liposomes were self-assembled with caffeine or O6-benzylguanine and four varieties of lipids and tagged with Dylite 755 and Dylite 680. These liposomes were then sized through UV-Visible spectroscopy, Dynamic Light Scattering indicated fluorophore attachment, and zeta potential analysis indicated charge of the liposomes. Two glioblastoma lines, U87 MG (MGMT-) and LN229 (MGMT+), were cultured on coverslips overnight and treated with 0.5 µM of O6-benzylguanine liposomes for various time points up to twenty-four hours, and this was repeated with 0.5 µM of caffeine only and 0.5 µM of both caffeine/O6-benzylguanine. Fluorescence microscopy of the slides showed an increase in uptake with time. Quantitative analysis showed that LN229 cells are more efficient in uptake than U87 MG cells. Results also indicated that the larger, more negative liposomes had less cellular uptake. Potential future directions include a pH-stability assay and varying the concentration of liposomes.