Oral Candida infections can be life-threatening in medically compromised patients. In particular non-albicans Candida strains are virulent. However, our knowledge is sparse on how proteolytic these strains are in patients with oral cancer. Our study aimed to investigate differences in proteolytic activity of non-albicans Candida and Candida albicans isolated from oral cancer patients. The hypothesis was based on anticipated different invasive capacity of the strains. Clinical and reference yeast samples from our laboratory were used for analyses. Candida strains were grown in yeast peptone glucose and the activity of Candida proteinases of broken cell fractions were analysed by MDPF-gelatin zymography. Fluorometric assay was used to compare activities of proteolytic enzymes and degradation assays were performed using CLDN 4 and plasma fibronectin. Clear differences were seen in the proteolytic activity between the studied non-albicans Candida and C. albicans strains. C. tropicalis had the highest proteolytic activity followed by strains of C. krusei and C. glabrata. The results confirmed our study hypothesis by showing differences between the non-albicans Candida and Candida albicans strains studied. Higher proteolytic activity may thus have an effect on the virulence of non-albicans Candida strains in oral cancer patients.
Keywords: Candida albicans; Non-albicans Candida; Oral cancer; Proteolysis.