<p dir="ltr">This thesis comprises three primary categories of data: clinical data, tumour data, and immune profiling of the hepatocellular carcinoma (HCC) tumours. </p><p dir="ltr">In the clinical dataset, expression levels of two methionine transporter genes, SLC7A6 and SLC43A2 were quantitatively evaluated using the Step One Real-Time PCR System (Applied Biosystems). These analyses were performed on paired specimens of HCC tumour tissue and corresponding adjacent non-tumourous tissue, collected from a cohort of 75 patients recruited at Queen Mary Hospital, The University of Hong Kong. The precise quantification of these transporters provides insight into tumour-associated metabolic reprogramming, particularly regarding methionine uptake mechanisms implicated in HCC pathophysiology.</p><p dir="ltr">In murine tumour studies, mice HCC models were established and subjected to dietary intervention, with groups allocated to either a control diet or a methionine-restricted diet. At the experimental endpoint, comprehensive tissue harvest and evaluation were conducted. Tumours were excised, and both the diameter and volume were measured to assess disease burden. Additionally, the weight of tumour-bearing livers was meticulously recorded to facilitate quantitative analysis of hepatic involvement. The presence and incidence of pulmonary metastases were systematically determined, providing critical insights into the metastatic potential under distinct nutritional regimens.</p><p dir="ltr">Finally, to interrogate the tumour immune microenvironment, immune profiling analyses were performed on tumour-bearing mice under control or methionine-restricted diets. Post-harvest, tumours were enzymatically dissociated into single-cell suspensions. These suspensions were subjected to multiparametric flow cytometric analysis using the BD LSRFortessa™ Cell Analyzer (BD Biosciences), enabling precise identification and quantification of distinct immune cell populations within the tumour milieu. The enumeration of immune subsets and comparative analyses between dietary groups elucidated the immunomodulatory effects of methionine restriction on HCC, revealing potential mechanistic links between nutrient availability and tumour-associated immune responses.</p><p><br></p>