Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


Jeffrey Alan Wojton Jr Dissertation.pdf (4.48 MB)

ETD Abstract Container

Abstract Header

SapC-DOPS Nanotherapy for the Treatment of Glioblastoma

Wojton, Jeffrey Alan, Jr.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1395416721

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Neuroscience Graduate Studies Program.
Glioblastoma (GB) is the most common and deadly primary brain tumor, which despite decades of basic/translational research and clinical trials, the survival rate remains dismal at 14-15 months. Due to the genomic/molecular deregulation, difficulties in drug delivery, and extreme tumoral heterogeneity, traditional therapeutics have been disappointing and innovative treatment strategies are needed. Saposin C-dioleoylphosphatidylserine (SapC-DOPS) nanovesicles are a nanotherapeutic that have been shown to effectively target and destroy cancer cells, while leaving untransformed cells unharmed. In this dissertation document we explore the feasibility of SapC-DOPS as putative treatment for brain tumors, with a specific focus on the targeting ability, anti-tumor efficacy, and capability for combination with chemotherapy in GB. We first explored the systemic use of SapC-DOPS in several models of brain cancer, including glioblastoma (GB), and the molecular mechanism behind its tumor-selective targeting specificity. Using two validated spontaneous brain tumor models we demonstrate the ability of SapC-DOPS to effectively cross the blood-brain tumor barrier to specifically target brain tumors in vivo and reveal the targeting to be contingent on the exposure of the anionic phospholipid phosphatidylserine (PtdSer). Increased cell surface expression of PtdSer levels was found to correlate with SapC-DOPS-induced killing efficacy, and blocking PtdSer exposed on cells inhibited tumor targeting in vivo. Apart from cancer cell killing, SapC-DOPS also exerted a strong anti-angiogenic activity in vitro and in vivo. Interestingly, unlike traditional chemotherapy, hypoxic cells were sensitized to SapC-DOPS mediated killing. Systemically administered SapC-DOPS was observed to significantly enhance survival in two orthotopic GB xenograft models. Next we explored the mode of action for SapC-DOPS in GB. While lacking both morphological and biochemical features of apoptosis and necroptosis, treatment with SapC-DOPS induced JNK mediated autophagy in human GB cells. However, downregulation of autophagy signaling genes ATG5 and BECN1 by RNAi was unable to block the cytotoxic effects of SapC-DOPS, indicating autophagy as a nonessential mechanism for SapC-DOPS induced GB cell death. Interestingly, SapC-DOPS treatment led to lysosomal dysfunction of GB cells characterized by decreased glycosylation of LAMP1 and altered proteolytic processing of cathepsin D. We observed that SapC-DOPS induced lysosomal membrane permeability (LMP) as shown by LysoTracker Red and Acridine Orange staining along with an increase of sphingosine, a known inducer of LMP. The culmination of this lysosomal damage resulted in a significant reduction in cellular ATP levels and necrotic cell death. Lastly, we examined the effects of SapC-DOPS treatment in combination with the GB standard of care chemotherapeutic temozolomide (TMZ). Combination of TMZ and SapC-DOPS displayed strong synergistic interactions in both serum-cultured traditional GB cell lines and primary GB neurosphere cultures through several mechanisms. This synergy appeared to be dependent on the GB cells sensitivity to TMZ, as GB cells resistant to TMZ displayed additive interactions combined with SapC-DOPS. The combination of TMZ and SapC-DOPS in vivo yielded a reduction in tumor size and a significant increase in survival compared to single treatments. Collectively, the results presented in this doctoral thesis establish the preclinical groundwork for SapC-DOPS as an effective and innovative therapeutic for GB.
Balveen Kaur, PhD (Advisor)
Deliang Guo, PhD (Committee Member)
Chang-Hyuk Kwon, PhD (Committee Member)
Arnab Chakravarti, MD (Committee Member)
160 p.
Neurosciences
glioblastoma nanotherapy SapC-DOPS

Recommended Citations

Citations

  • Wojton, Jr., J. A. (2014). SapC-DOPS Nanotherapy for the Treatment of Glioblastoma [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1395416721

    APA Style (7th edition)

  • Wojton, Jr., Jeffrey. SapC-DOPS Nanotherapy for the Treatment of Glioblastoma. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1395416721.

    MLA Style (8th edition)

  • Wojton, Jr., Jeffrey. "SapC-DOPS Nanotherapy for the Treatment of Glioblastoma." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1395416721

    Chicago Manual of Style (17th edition)

osu1395416721
174
© 2014, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.