Antiglioma Potential of Coumarins Combined with Sorafenib

Abstract

Coumarins, which occur naturally in the plant kingdom, are diverse class of secondary metabolites. With their antiproliferative, chemopreventive and antiangiogenetic properties, they can be used in the treatment of cancer. Their therapeutic potential depends on the type and location of the attachment of substituents to the ring. Therefore, the aim of our study was to investigate the effect of simple coumarins (osthole, umbelliferone, esculin, and 4-hydroxycoumarin) combined with sorafenib (specific inhibitor of Raf (Rapidly Accelerated Fibrosarcoma) kinase) in programmed death induction in human glioblastoma multiforme (T98G) and anaplastic astrocytoma (MOGGCCM) cells lines. Osthole and umbelliferone were isolated from fruits: Mutellina purpurea L. and Heracleum leskowii L., respectively, while esculin and 4-hydroxycoumarin were purchased from Sigma Aldrich (St. Louis, MO, USA). Apoptosis, autophagy and necrosis were identified microscopically after straining with specific fluorochromes. The level of caspase 3, Beclin 1, PI3K (Phosphoinositide 3-kinase), and Raf kinases were estimated by immunoblotting. Transfection with specific siRNA (small interfering RNA) was used to block Bcl-2 (B-cell lymphoma 2), Raf, and PI3K expression. Cell migration was tested with the wound healing assay. The present study has shown that all the coumarins eliminated the MOGGCCM and T98G tumor cells mainly via apoptosis and, to a lesser extent, via autophagy. Osthole, which has an isoprenyl moiety, was shown to be the most effective compound. Sorafenib did not change the proapoptotic activity of this coumarin; however, it reduced the level of autophagy. At the molecular level, the induction of apoptosis was associated with a decrease in the expression of PI3K and Raf kinases, whereas an increase in the level of Beclin 1 was observed in the case of autophagy. Inhibition of the expression of this protein by specific siRNA eliminated autophagy. Moreover, the blocking of the expression of Bcl-2 and PI3K significantly increased the level of apoptosis. Osthole and sorafenib successfully inhibited the migration of the MOGGCCM and T98G cells.

Natural Compounds in Glioblastoma Therapy: Preclinical Insights, Mechanistic Pathways, and Outlook

“…Finally, Akt activity can be reduced through the downregulation of PI3K. Eucalyptal A downregulates PI3K by inhibiting SRSF1 and MYO1B, while curcumin, osthole, diosgenin, and berberine downregulate PI3K directly [29,32,54,64]. Downstream, Akt upregulates the mammalian target of rapamycin (mTOR) and nuclear factor κappa of activated B cells (NF-κB), which induce proliferation.…”

“…Finally, ERK MAPKs upregulate hypoxia-inducible factor 1 αlpha (HIF-1α), whose downstream target is the epidermal growth factor receptor (EGFR). Osthole, a coumarin, may inhibit MEK activation in the second step through the downregulation of Raf [ 64 ]. TBMS1 may have a similar inhibitory function, as it downregulates MET [ 41 ].…”

“…Downstream, cytochrome c, Bad, and Bim promote the activation of caspase 9, which in turn activates caspase 3. A blockade of Akt/mTOR signaling mediated by arctigenin or osthole enhances the activity of Beclin-1, which supports caspase 3 activation [ 61 , 64 ]. Caspase 3 specifically blocks the inhibitor of caspase-activated DNAse (ICAD), allowing CAD to cause DNA fragmentation—an effect observed after diosgenin application [ 54 ].…”

“…However, arctigenin and osthole upregulate Beclin-1 mRNA and protein levels. Beclin-1 interestingly has dual roles in apoptosis and autophagy, and upregulates light chain 3B (LC3B), which promotes autophagosome formation [ 61 , 64 ]. Moreover, arctigenin may increase autophagy through the upregulation of phosphorylated P62 (p-P62) [ 61 ].…”

Trending Topics on Coumarin and Its Derivatives in 2020

“…Within the group of compounds with anticancer activity, coumarins exhibiting an antiglioma profile may be highlighted. Simple coumarins such as osthole, umbelliferone, esculin, and 4-hydroxycoumarin, combined with sorafenib (a kinase inhibitor drug approved for the treatment of primary kidney cancer, advanced primary liver cancer, FLT3-ITD positive acute myeloid leukemia (AML), and radioactive iodine-resistant advanced thyroid carcinoma) were studied [ 16 ]. The same group also studied a combination of the same simple coumarins with temozolomide (used in the treatment of brain tumors such as glioblastoma multiforme or anaplastic astrocytoma) [ 17 ].…”