Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 63 2 2025 07 09 83 97 Abbas Abed Noor Al-Owaidi Department of Biology, College of Sciences, University of Babylon, Babylon, Hillah, 51001, Iraq Mohammed Abdullah Jebor Department of Biology, College of Sciences, University of Babylon, Babylon, Hillah, 51001, Iraq 2025 01 05 2025 02 03 L-methioninase (L-Met), a methionine-degrading enzyme, has shown potential for anticancer therapy. Many tumor tissues have a limited ability to produce methionine and depend on external sources; hence, these tumors can be targeted by methionine-based treatments. The present study was conducted to investigate the effects of L-Met on cancer cells, particularly hepatocellular carcinoma (HepG2) and pancreatic carcinoma (PANC-1), and to evaluate its viability as a therapeutic agent. Various techniques, including ammonium sulfate precipitation, dialysis, ion-exchange chromatography, and gel filtration chromatography, were employed to purify the enzyme L-Met. A cytotoxicity test was conducted against HepG2 and PANC-1 cells (at 25-200 µg/mL concentrations), using the MTT to evaluate cell viability, total nuclear intensity (TNI), and cell membrane permeability (CMP). Statistical analysis was done using one-way ANOVA and Dunnett's multiple comparisons test to compare study groups. L-Met displayed dose-dependent growth inhibition of the specified cell lines. The PANC-1 cell line exhibited an IC50 of 64.68 µg/mL, indicating a higher sensitivity to L-Met compared to WRL 68 normal cells, which had an IC50 of 214.0 µg/mL. Regarding HepG2, an even lower IC₅₀ of 66.44 µg/mL was observed, further confirming the selective targeting of cancer cells by L-Met. Treatment with L-Met at a 200 µg/mL concentration significantly decreased TNI and CMP levels in both the PANC-1 and HepG2 cell lines, indicating increased cytotoxicity and compromised membrane integrity. Additionally, L-Met reduced matrix metalloproteinase activities in both cancer cell lines, a critical factor in metastasis. Our study demonstrates the dose-dependent cytotoxic effects of L-Met on methionine-dependent tumor cells, specifically HepG2 and PANC-1. These findings highlight the need for optimized L-Met dosing strategies in cancer treatment, particularly for methionine-dependent malignancies, paving the way for its potential use in targeted cancer therapy. https://acta.tums.ac.ir/index.php/acta/article/view/11460