Do derived whitecheek shark proteins motivate T cells to fight cancer cells? A case study in using SW742 cell line

Shark cartilage is considered as a natural dietary supplement consisting of anti-angiogenic, immunostimulatory, and anti-inflammatory characteristics. Therefore, this study was designed to inspect the possibility that whitecheek shark (Carcharhinus dussumieri) cartilage proteins motivate expression of NKG2D, CXCR3, NKP46, and NKP44 receptors on natural killer cells and their activities against SW742 cell line. To this end, cartilaginous areas of whitecheek shark were caught, minced, stored at −20°C and then lyophilized and kept in refrigerator. Peripheral blood samples were collected from healthy people and a number of 10⁶ cells were considered for cell viability using trypan blue method. Activation of NK cells was determined using 10⁶ cells stimulated following exposure to 0.2 and 3 mg mL^-1 extracted shark cartilage proteins in 4, 8, and 18 h incubation. The results showed that cytotoxicity of NK cells increased significantly by elevating the concentration of extracted proteins at incubation period of 24 h (p˂0.05). The findings demonstrated that NK activity elevated markedly by increasing the concentration and volume of protein suspension and the exposure time (p˂0.05). Interestingly, the expression of NKG2D, CXCR3, NKP44, and NKP46 receptors was not significant in any transcription level by exposing to 0, 25, and 75 µg mL^-1 in 4, 8, and 18 h incubation period (p˃0.05). Together, extracted shark cartilage protein could motivate the immune system capabilities through using NK cells against cancer tissues but specific receptors on T cells cannot be activated by these bioactive materials.