Abstract 6332: Pegylated arginase isolated from beef liver tissue inhibited cell proliferation, induced apoptosis & inhibits induced mammary tumors in human breast cancer in vitro & in vivo
Authors: Ali Asmaa , Ali Omnia , Othman Doaa , Sultan Ahmed 
Published: June 2022

Arginase, an enzyme of the urea cycle, converts L-arginine to L-ornithine, which is the precursor of polyamines that are essential components of cell proliferation. However, Arginine deprivation and Arginase clinical implications in human breast and liver cancers have not been fully elucidated. The objective of the current study was to investigate the potential role of the Arginine degrading enzyme, Arginase, on three cell lines; Luminal A breast cancer (T-47D), TNBC (MDA-MB-231), and HCC cell line, HepG2, respectively. Herein, Arginase was extracted and purified from the beef liver and its specific activity was 0.2 IU/mg protein yielded 49% compared to the crude beef liver Arginase. The purified Arginase is covalently bound via a succinamide propionic acid (SPA) linker to polyethylene glycol (PEG) of molecular weight 5,000 to enhance the half-life time compared to the native enzyme with a maximum specific activity between 37~55℃ and pH 7~9. The potential influence of extracted Peg-Arginase was examined on cell proliferation, clonogenic assays, morphological alteration, and oncogenic signaling pathways of STAT3, β-catenin, and miR-23a. Our data showed that Peg-Arginase treatment displayed a significant inhibition in cell proliferation and viability in a dose-dependent manner in both breast cancer cell lines, but not in HepG2 cells after 48h. Furthermore, mechanistic studies showed that Peg-Arginase induced apoptosis that was associated with cell morphological changes, histone release from fragmented DNA, caspase-3 activation in a dose-dependent manner after 48h, and cell cycle arrest at S and/or G2/M phases. Moreover, Peg-Arginase down-regulated miR-23a, STAT3, β-catenin, cyclin D1, and mutant p53 levels as well as increased p21and Bax, pro-apoptotic signal, in both breast cancer cells as determined by flow cytometry and western blot analysis. In vivo, the effects of native- and Peg-Arginase enzymes were examined on MNU-induced mammary tumors in Albino-Wister rats. Our data showed that 400 IU of native- or peg- Arginase twice per week for two weeks significantly inhibited the growth of MNU-induced mammary tumors by 58.8±4.1 % for peg-Arginase compared to 19.7±3.5 % for native-Arginase. Furthermore, the results also revealed a significant reduction in activities of ALT, AST, and ALP in the Peg-Arginase group compared to MNU untreated or native-Arginase groups, suggesting that Peg-Arginase may eliminate the hepatotoxic effect of the MNU. All in all, our results suggested that the arginine-depleting enzyme, Peg-Arginase, exerted an anticancer effect against both T-47D and MDA-MB-231 breast cancer cell lines through cell proliferation inhibition and apoptosis induction.

Citation Format: Asmaa Ali, Omnia Ali, Doaa Othman, Ahmed Sultan. Pegylated arginase isolated from beef liver tissue inhibited cell proliferation, induced apoptosis & inhibits induced mammary tumors in human breast cancer in vitro & in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6332.