Phloretin suppresses metastasis by targeting protease and inhibits cancer stemness and angiogenesis in human cervical cancer cells

Background: Phloretin, a dihydrochalcone flavonoid, possesses anti-inflammatory activity and inhibits the growth of various cancers. However, the flavonoid's effect on cervical cancer metastasis and angiogenesis remains unknown. Purpose: In this study, we provide molecular evidence associated with the antimetastatic and antiangiogenic effects of phloretin. Methods: In this study, the anti-invasive effect of phloretin (0–60 μM)in cervical cancer cells was evaluated using the Matrigel invasion assay, gelatin zymography, cell-matrix adhesion assay, wound healing assay, and Western blotting. Antiangiogenic potential of phloretin (0–100 μM)was assessed by the Matrigel tube formation assay. The in vivo antitumor effect of phloretin (10 or 20 mg/kg)was fed by oral gavage and determined using subcutaneous inoculation and tail vein injection in immunodeficient nude mice. Results: Phloretin (60 μM)showed marked suppression of invasion and migration through downregulation of matrix metalloproteinase (MMP)-2, MMP-3, and cathepsin S in human SiHa cervical cancer cells. Phloretin (60 μM)reversed the epithelial-mesenchymal transition induced by transforming growth factor-β1 and downregulated mesenchymal markers, such as fibronectin, vimentin, and RhoA. Phloretin (100 μM)treatment significantly inhibited the aldehyde dehydrogenase 1 activity of SiHa cells, reduced the self-renewal properties and stemness signatures of CD44 and Sox-2 in sphere-forming cervical cancer-derived tumor-initiating cells, and inhibited the invasion, MMP-2 activity, and tube formation capacity of human umbilical vein endothelial cells. The ability of phloretin (20 mg/kg)to suppress lung metastasis and tumor growth in SiHa cells was evidenced by tail vein injection and subcutaneous inoculation in a tumor xenograft model. Conclusion: In summary, the findings indicate that phloretin inhibits the metastatic and angiogenic abilities and cancer stemness of SiHa cells, thereby suggesting that this flavonoid is a promising therapeutic agent for the treatment of human cervical cancer cells.