Calpain 2 proteolysis regulates glioblastoma cell invasion Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/z029p7807

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Glioblastoma is the most malignant primary brain tumor with the average patients surviving only one year after diagnosis, even with aggressive therapy. The formation of numerous micro-tumors dispersed into the brain due to rapid invasion of tumor cells, presents the primary challenge to the surgical removal of tumors and limits the effectiveness of current treatments. This dissertation presents studies aimed at understanding the molecular mechanisms regulating invasion of human glioblastoma cells. Transplantation of human glioblastoma cells in the zebrafish brain showed that the knockdown of calpain 2, a calcium-activated protease, resulted in a three fold decrease in the tumor cell invasion. The result was further verified in the organotypic mouse brain slices where the knockdown cells demonstrated 2-fold decrease in the area of dispersal compared to control cells. Our data show that calpain 2 plays a role in the process of tumor cell angiogenesis. Glioblastoma cells were transplanted into the brain of zebrafish expressing GFP in the blood vessels and we observed that 23% of animals injected with control tumor cells demonstrated angiogenesis. In contrast, only 9% of fish that received calpain 2 knockdown cells showed the formation of new vessels. Consistent to the reports from human glioblastoma patients and rodent models, we did not observe metastasis of transplanted cells outside of the brain in the zebrafish, supporting for the use of zebrafish as an important model for glioblastoma cell invasion studies. These results provide evidence that calpain 2 protease activity is required for the dispersal of glioblastoma cells in the brain microenvironment. To determine the mechanism of calpain 2 regulation of tumor cell invasion, proteolysis of filamin by calpain 2 was studied. Filamin is an important actin cross-linking protein which develops orthogonal actin networks in the periphery of the cell. In this study, we show that the expression of filamin inhibits glioblastoma cell invasion. Hence, knocking down filamin expression by 80% resulted in 220% increase in the invasion of glioblastoma cells through Matrigel extracellular matrix. The regulated proteolysis of filamin is a potential mechanism to facilitate the cyclic turnover of actin orthogonal networks which is required for glioblastoma cell invasion. In this study, we identified a novel mechanism that the PI3 kinase activity regulates the cleavage of filamin by calpain 2 in glioblastoma cells. Binding of a membrane phospholipid phosphatidylinositol (3,4,5) triphosphate [PtdIns (3,4,5)-P₃] to filamin induces its proteolysis by calpain 2 after the amino acid lysine 268, removing the actin binding domain which in-turn abolishes the actin binding ability of filamin.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Keyword
Rights Statement
Language
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2011-02-01T16:47:49Z (GMT). No. of bitstreams: 3 Ph.D. Dissertation_Sangeet Lal.pdf: 4707423 bytes, checksum: c082b261ac2f3faa170d40b927980dfa (MD5) license_rdf: 21755 bytes, checksum: eaa6a1b0f59554f6c24f682a7820bfa8 (MD5) license_text: 18940 bytes, checksum: 9f1d4f39797aa527f961c4388fbfab36 (MD5)
  • description.provenance : Approved for entry into archive by Laura Wilson(laura.wilson@oregonstate.edu) on 2011-02-01T16:47:48Z (GMT) No. of bitstreams: 3 Ph.D. Dissertation_Sangeet Lal.pdf: 4707423 bytes, checksum: c082b261ac2f3faa170d40b927980dfa (MD5) license_rdf: 21755 bytes, checksum: eaa6a1b0f59554f6c24f682a7820bfa8 (MD5) license_text: 18940 bytes, checksum: 9f1d4f39797aa527f961c4388fbfab36 (MD5)
  • description.provenance : Submitted by Sangeet Lal (lals@onid.orst.edu) on 2011-01-28T21:08:53Z No. of bitstreams: 3 Ph.D. Dissertation_Sangeet Lal.pdf: 4707423 bytes, checksum: c082b261ac2f3faa170d40b927980dfa (MD5) license_rdf: 21755 bytes, checksum: eaa6a1b0f59554f6c24f682a7820bfa8 (MD5) license_text: 18940 bytes, checksum: 9f1d4f39797aa527f961c4388fbfab36 (MD5)
  • description.provenance : Approved for entry into archive by Julie Kurtz(julie.kurtz@oregonstate.edu) on 2011-01-31T21:36:55Z (GMT) No. of bitstreams: 3 Ph.D. Dissertation_Sangeet Lal.pdf: 4707423 bytes, checksum: c082b261ac2f3faa170d40b927980dfa (MD5) license_rdf: 21755 bytes, checksum: eaa6a1b0f59554f6c24f682a7820bfa8 (MD5) license_text: 18940 bytes, checksum: 9f1d4f39797aa527f961c4388fbfab36 (MD5)

Relationships

In Administrative Set:
Last modified: 08/14/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items