Nomilin inhibits metastasis via induction of apoptosis and regulates the activation of transcription factors and the cytokine profile in B16F-10 cells.

Nomilin is a triterpenoid present in common edible citrus fruits with putative anticancer properties. In this study, the authors investigated the antimetastatic potential of nomilin and its possible mechanism of action. Metastasis was induced in C57BL/6 mice through the lateral tail vein using highly metastatic B16F-10 melanoma cells. Administration of nomilin inhibited tumor nodule formation in the lungs (68%) and markedly increased the survival rate of the metastatic tumor-bearing animals. These results correlated with the biochemical parameters and histopathological analysis. Nomilin showed an inhibition of tumor cell invasion and activation of matrix metalloproteinases. Treatment with nomilin induced apoptotic response, characterized by an increase in the sub-G1 fraction of cells with chromatin condensation and membrane blebbing, a typical ladder of DNA fragmentation, and detection of apoptotic cells by TUNEL assay. Nomilin treatment also exhibited a downregulated Bcl-2 and cyclin-D1 expression and upregulated p53, Bax, caspase-9, caspase-3, p21, and p27 gene expression in B16F-10 cells. Proinflammatory cytokine production and gene expression were found to be downregulated in nomilin-treated cells. The study also reveals that nomilin could inhibit the activation and nuclear translocation of antiapoptotic transcription factors such as nuclear factor (NF)-κB, CREB, and ATF-2 in B16F-10 cells.