Betulinic acid, a plant-derived natural extract with a wide range of biologic properties, has demonstrated antitumor potential in human renal cell cancer cells in vitro and in vivo, according to research published in the Journal of Cellular Biochemistry.
An evaluation using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and clone formation assays revealed that betulinic acid exerts cytotoxic and cytostatic effects on renal cancer cells.
“Despite considerable progress in the diagnosis and treatment of RCC over the last decades, the long-term prognosis is still unsatisfactory,” wrote the authors, led by Chunming Yang, Department of Urology, The First Affiliated Hospital, China Medical University, Shenyang, China. “Hence, there is a critical need to develop novel and effective therapeutic strategies for RCC.”
Betulinic acid has shown promising activity in multiple types of human cancer, including prostate cancer, colon cancer, malignant head and neck cancer, pancreatic cancer, breast cancer, lung cancer, skin cancer, and cervical cancer. The investigators sought to examine its antitumor potential in human real carcinoma cells using MTT cell proliferation and cytotoxicity assays.
Tumor volume was measured in a xenograft tumor model in which mice were administered 0, 5, and 10 mg/kg of betulinic acid or saline.
Proliferation of 786-O and ACHN cells (renal cell carcinoma cells) was inhibited by betulinic acid in a concentration-dependent and time-dependent manner, and clonogenic activity of 786-O and ACHN cells was inhibited in a dose-dependent manner.
Flow cytometry also demonstrated that betulinic acid induced renal cell carcinoma cell apoptosis. Western blot analysis showed that apoptosis was associated with a concentration-dependent decrease in expression of Bcl2 in 786-O and ACHN cells treated with betulinic acid compared with untreated cells, and a dose-dependent increase in the expression of Bax and cleaved caspase-3.
Loss of mitochondrial membrane potential and augmentation of the production of reactive oxygen species with betulinic acid suggests that apoptosis was induced through a mitochondria-mediated pathway.
Migration and invasion are key steps in metastasis of cancer cells. Betulinic acid treatment repressed 786-O and ACHN cell migration and invasion in a dose-dependent manner. Western blot analysis showed that betulinic acid treatment increased the expression of matrix metalloproteinase (MMP)2, MMP9, and vimentin, and lowered the expression of tissue inhibitor of metalloproteinases (TIMP)2 and E-cadherin compared with the vehicle group.
“Upregulation of MMP2, MMP9, and vimentin, and downregulation of TIMP2 and E? cadherin are associated with the acquisition of invasive and aggressive phenotypes in cancer cells,” the authors wrote.
In vivo effects of betulinic acid were consistent with in vitro effects. Betulinic acid retarded the growth of 786-O cells in the xenograft model of renal cell carcinoma compared with controls administered the vehicle. Fewer Ki67-positive and MM9P-positive cells were observed in tumors removed of betulinic acid-treated mice compared with controls, indicating that betulinic acid impeded renal tumor growth in vivo.
Hematoxylin-and-eosin staining of visceral organs showed no pathologic alterations, leading the investigators to suggest that betulinic acid may be safe for treating renal cell carcinoma.
To read more about this study, click here.