Neisha Ramírez Serrano, BS
Lilia Kucheryavykh, PhD

Department of Biochemistry, Universidad Central del Caribe, Bayamón, Puerto Rico

Introduction

Glioblastoma (GBM) is an aggressive primary brain tumor with a profoundly immunosuppressive microenvironment that limits treatment success. One mechanism by which GBM cells influence immune responses is through extracellular vesicles (EVs), which facilitate tumor progression. This study investigates the impact of Proline-Rich Tyrosine Kinase 2 (Pyk2) and MEK/ERK signaling on EV biogenesis and immune modulation in GBM. We propose that Pyk2/MEK/ERK signaling regulates EV secretion by remodeling the actin cytoskeleton, thereby influencing tumor-associated macrophage (TAM) activation.

Methods

Using CRISPR/Cas9, Pyk2 was knocked out (Pyk2KO) in two primary human GBM cell lines. EVs were analyzed via flow cytometry, western blot, and PCR to assess their composition and size distribution. Immunomodulatory cytokine levels were measured to evaluate alterations in immune signaling.

Results

Loss of Pyk2 led to a shift toward larger EVs and a reduction in Integrin+ EV subpopulations compared to wild-type (WT) cells. Furthermore, EVs derived from Pyk2KO cells showed a marked decrease in key immunomodulatory cytokines, including CCL2, CCL5, TNF, and VEGF.

Conclusion

These findings highlight Pyk2 as a crucial regulator of EV dynamics in GBM, suggesting that modulating Pyk2 and MEK/ERK signaling could help counteract EV-mediated immune suppression. A deeper understanding of these pathways may open new avenues for enhancing immunotherapeutic approaches in GBM treatment.

Funding

NIH Grant 1R15CA287203

Keywords

Glioblastoma, Pyk2, Vesicles, TNF, VEGF