Generating Shigella that internalize into glioblastoma cells

Austin Shipley; Gabriel Frampton; Bryan W Davies; Benjamin J Umlauf

doi:10.3389/fonc.2023.1229747

Generating Shigella that internalize into glioblastoma cells

Front Oncol. 2023 Nov 23:13:1229747. doi: 10.3389/fonc.2023.1229747. eCollection 2023.

Authors

Austin Shipley¹, Gabriel Frampton¹, Bryan W Davies^{2

3}, Benjamin J Umlauf^{1

4}

Affiliations

¹ Department of Neurosurgery, Dell Medical School, The University of Texas at Austin, Austin, TX, United States.
² Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, United States.
³ John Ring LaMontagne Center for Infectious Diseases, The University of Texas at Austin, Austin, TX, United States.
⁴ Mulva Clinic for the Neurosciences, The University of Texas at Austin, Austin, TX, United States.

Abstract

Introduction: The use of microorganisms as drug delivery systems to treat cancer has expanded recently, including FDA approval of certain viruses as oncolytics. Microorganisms have several unique benefits compared to traditional pharmacologic agents including dose independence, the ability to produce therapeutic proteins locally within the tumor, and simplicity of administration. However, current microbial delivery systems such as AAV9 and herpes virus have limited cassette sizes, minimal cancer cell selectivity, and low innate cytotoxicity. To address these issues, we sought to generate a strain of Shigella flexneri to selectively internalize into glioblastoma (GBM) brain tumor cells as an initial step to generating a bacterial-based drug delivery system.

Methods: We generated S. flexneri that selectively internalize into GBM cells using iterative co-cultured assays.

Results: After 50 rounds of co-culture, the new strain infected 95 percent of GBM cells in 2 hours. GBM-infecting Shigella demonstrate a 124-fold preference for internalizing in nine different GBM cell lines compared to Normal Astrocytes (NA) controls. Additionally, we developed an in-cell western to identify GBM-infecting Shigella clones that preferentially internalize in patient samples without iterative co-culture. Finally, we demonstrate internalization into GBM cells is mediated via a factor modified by myristoylation.

Discussion: In conclusion, here we present a novel bacterial platform that preferentially internalizes in brain tumor cells. This system provides numerous potential benefits over current interventions and other microbial strategies for treating brain tumors.

Keywords: Shigella; drug delivery; glioblastoma; microbial factories; myristoylation.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study received financial support from the Mulva Clinic for the Neurosciences (BU).