The effects of cisplatin-ibuprofen conjugate free and immobilized in mesoporous nanostructured silica on the change of morphology of mouse melanoma cells, and antitumor potential in vivo

Abstract

Background: Active contribution of cyclooxygenase enzymes (COX) and their products, in particular prostaglandin E2, to tumor progression makes this enzyme an attractive target for molecular therapy in cancer. The combination of conventional chemotherapeutic drugs with COX1/2 inhibitors, and further enhancement of their delivery into target tissue can be a highly prospective approach in cancer therapy, especially in advanced stages. Accordingly, a cytostatic and anti-inflammatory drug conjugate was synthesised, as well as its immobilization in mesoporous nanostructured silica SBA-15. Detailed evaluation of the cytotoxic potential and the mechanism of action of this conjugate and the appropriate material on B16 cells was further performed in vitro and in vivo. Material and Methods: Cell viability of B16 melanoma cells was determined by MTT and CV assays. Cell morphology was estimated by hematoxylin–eosin and Oil Red O staining using light microscopy, while changes in the nuclei were validated by PI staining using fluorescent microscopy. Differentiation of melanoma cells was determined by measurement of tyrosinase activity and the presence of melanin. Syngeneic C57BL/6 mice model was used for in vivo assessment of the tumorigenic potential of B16 cells exposed to free and SBA-15 loaded conjugate in vitro, as well as for the evaluation of the antitumor potential of the experimental substances given in the therapeutic regimen. Results and Conclusion: Exposure to free or immobilized cisplatin-ibuprofen conjugate decreased the viability of the B16 cell culture while morphology of survived cells was changed. Cytoplasm of enlarged and elongated cells showed intensive granularity with enhanced lipid content and huge irregularly shaped nuclei with prominent heterochromatin foci, all of which indicated senescent state. Increased activity of tyrosinase and the presence of melanin compared to the control, referred to the differentiation of melanoma cells toward primary phenotype. Further inoculation of pretreated B16 cells into C57BL/6 mice showed decreased potential to form tumor in comparison to tumorigenic potential of untreated cells. Additionally, in vivo application of free and SBA-15 immobilized conjugate in therapeutic regiment led to statistically significant reduction of tumor volume, with only fewer signs of toxicity compared to cisplatin as positive control. New knowledge about this compound and corresponding material is reflected in their antitumor potential on mouse melanoma cells, which opens numerous possibilities for further research.