(164g) Peptide Aggregation Induced Immunogenic Rupture (PAIIR) on Breast Cancer Spheroid Model

Gokhan Gunay M.Sc., PhD Candidate: Gokhan.Gunay-1@ou.edu

Inducing cell death was the primary goal of treatment strategies against cancer for decades. However, emerging results are showing that the type of cell death dictates the progression of the tumor. Induction of apoptosis within the tumor micro environment (TME) leads to suppression of the immune system, increased proliferation of cancer cells and reduced inflammation, all of which increase the progression of cancer ¹. Immunogenic cell death (ICD) on the other hand results in secretion, release or surface expression of damage-associated molecular patterns (DAMPs), natural adjuvants capable of engaging immune system². Current ICD inducing strategies involve chemotherapeutics, radiation therapy and photothermal therapy. However, their effects on inducing ICD and DAMP release have been predominantly studied in classical monolayer cultures. 3D tumor spheroid models offer a bridge to in vivo studies and reflect physiological relevance to in vivo tumors in terms of drug resistance and zone formation due to reduced nutrient and oxygen diffusion ³. Therefore, utilization of such models for understanding ICD and DAMP release will serve as a more physiologically relevant and high-throughput system for not just understanding the effects of current strategies but also engineer new materials.

Previously we engineered a co-assembly of oppositely charged peptide (CoOP) platform⁴ which leverages the characteristics of amino acids such as hydrophobicity to induce immunogenic cell death⁵, which is called peptide aggregation induced immunogenic rupture (PAIIR). Here, we applied this newly developed technology into a breast cancer spheroid model by using EMT6 cells. We compared PAIIR technology with a known ICD inducer mitoxantrone and a known non-ICD inducer cisplatin. We showed that PAIIR treatment is superior in terms of DAMP release from spheroids and the released DAMPs can engage dendritic cells into a pro-inflammatory phenotype. Engineering new materials that can induce ICD within TME hold great potential for evoking adaptive immunity. Spheroids offer a bridge between in vitro and in vivo studies through reflecting certain physiological features of in vivo tumors.

Figure 1 Peptide aggregation induced immunogenic rupture (PAIIR) for induction of ICD in breast cancer spheroid model. A. Spheroid formation technique. B. Extracellular ATP release. C. Design of bone marrow dendritic cells (BMDCs) activation. D. IL-1b release from BMDCs

References

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3. Yan, F. et al. Characterization and quantification of necrotic tissues and morphology in multicellular ovarian cancer tumor spheroids using optical coherence tomography. Biomed. Opt. Express, BOE 12, 3352–3371 (2021).
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5. Gunay, G. et al. Peptide Aggregation Induced Immunogenic Rupture (PAIIR). BioRxiv 472230, (2021).