Antibacterial and anticancer activity of two NK-lysin-derived peptides from the Antarctic teleost Trematomus bernacchii

• Published in: Fish & shellfish immunology 2023-11, Vol.142, p.109099-109099, Article 109099
• Main Authors: Buonocore, F., Saraceni, P.R., Taddei, A.R., Miccoli, A., Porcelli, F., Borocci, S., Gerdol, M., Bugli, F., Sanguinetti, M., Fausto, A.M., Scapigliati, G., Picchietti, S.
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii; Antimicrobial peptides; Enterococcus faecalis; Melanoma cells; NK-lysin; Trematomus bernacchii
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2023.109099

The NK-lysin antimicrobial peptide, first identified in mammals, possesses both antibacterial and cytotoxic activity against cancer cell lines. Homologue peptides isolated from different fish species have been examined for their functional characteristics in the last few years. In this study, a NK-lysin transcript was identified in silico from the head kidney transcriptome of the Antarctic teleost Trematomus bernacchii. The corresponding amino acid sequence, slightly longer than NK-lysins of other fish species, contains six cysteine residues that in mammalian counterparts form three disulphide bridges. Real time-PCR analysis indicated its predominant expression in T. bernacchii immune-related organs and tissues, with greatest mRNA abundance detected in gills and spleen. Instead of focusing on the full T. bernacchii derived NK-lysin mature molecule, we selected a 27 amino acid residue peptide (named NKL-WT), corresponding to the potent antibiotic NK-2 sequence found in human NK-lysin. Moreover, we designed a mutant peptide (named NKL-MUT) in which two alanine residues substitute the two cysteines found in the NKL-WT. The two peptides were obtained by solid phase organic synthesis to investigate their functional features. NKL-WT and NKL-MUT displayed antibacterial activity against the human pathogenic bacterium Enterococcus faecalis and the ESKAPE pathogen Acinetobacter baumannii, respectively. Moreover, at the determined Minimum Inhibitory Concentration and Minimum Bactericidal Concentration values against these pathogens, both peptides showed high selectivity as they did not exhibit any haemolytic activity on erythrocytes or cytotoxic activity against mammalian primary cell lines. Finally, the NKL-MUT selectively triggers the killing of the melanoma cell line B16F10 by means of a pro-apoptotic pathway at a concentration range in which no effects were found in normal mammalian cell lines. In conclusion, the two peptides could be considered as promising candidates in the fight against antibiotic resistance and tumour proliferative action, and also be used as innovative adjuvants, either to decrease chemotherapy side effects or to enhance anticancer drug activity. •NK-lysin sequence was identified in silico from T. bernacchiii.•NK-lysin transcripts were predominantly expressed in T. bernacchii gills and spleen.•A wild-type and a mutant peptide were selected from the NK-lysin sequence.•Wild-type and mutant peptides exhibited bactericidal effects.•Mutant peptid