Abstract 2029: Investigation of anti-tumor activity of porcine myeloperoxidase for urothelial carcinoma of the bladder

Abstract

Abstract Introduction: Porcine myeloperoxidase (pMPO) is a cationic enzyme secreted by granulocytic leukocytes capable of selectively binding cancer cells due to their negative surface charge. In the presence of hydrogen peroxide (H2O2) and sodium chloride (NaCl), MPO catalyzes the production of electronically excited singlet molecular oxygen, which exerts focused cytotoxic activity against cancer cells. Methods: Human bladder non-cancer (SV-HUC1) and cancer cells (T24 and 5637) were used to assess differential cytotoxic activity of pMPO. pMPO was combined with associated reagents, including H2O2, NaCl, and L-proline and glycine for 45 minutes to support the generation of singlet oxygen. MTS assay was used to assessed cell viability at day 3 post-treatment. Non-cancer and cancer cells were labeled with GFP and mCherry, respectively, via infection with lentivirus and cultured in tandem to allow for simultaneous treatment of both cell types. After the treatment, flow cytometry and microscopy were used to monitor the growth of the cells. Results: No cytotoxicity was noted when SV-HUC1 cells were cultured with individual reagents pMPO, NaCl, L-Proline, or Glycine, and limited cytotoxicity was observed with H2O2. Notably, cell viability was nearly maximally preserved for SV-HUC1 cells. The combination of pMPO with associated reagents resulted in killing of 5637 and T24 cells, with tumoricidal activity maintained across increasing tumor cell density, with cell viability preserved for SV-HUC1 cells. Within the cell co-culture system, simultaneous treatment of both cell types with the pMPO treatment resulted in selective killing of tumor cells and preservation of SV-HUC1 cells. Mechanistic studies confirm specificity of pMPO binding to tumor cells, and further, high levels of expression of gammaH2AX and phospho-ATM in 5637 and T24 cells following treatment. Conclusion: pMPO demonstrates selective and efficient killing of bladder cancer cells with minimal cytotoxicity against non-cancer urothelial cells. Given its reliance on direct surface contact with tumor cells for activity, pMPO may be developed as an intravesical therapy for treatment of non-muscle invasive bladder cancers. Acknowledgements: This work was partially supported by Mayo funds provided to Dr. Haojie Huang. Citation Format: Junnan Liu, Robert C. Allen, Jackson T. Stephens, Paras Shah, Haojie Huang. Investigation of anti-tumor activity of porcine myeloperoxidase for urothelial carcinoma of the bladder [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2029.