Subamolide B Isolated from Medicinal Plant Cinnamomum subavenium Induces Cytotoxicity in Human Cutaneous Squamous Cell Carcinoma Cells through Mitochondrial and CHOP-Dependent Cell Death Pathways
Figure 3
Subamolide B appears to engage the FasL/Fas cell death pathway. (a) Subamolide B upregulates FasL. SCC12 cells were treated with 0~20 μM of subamolide B for 24 h, followed by immunoblotting to monitor the levels of various death receptor ligands and their cognate receptors, including FasL/Fas and TRAIL/DR5. β-tubulin was used as the loading control. (b) Subamolide B treatment increases the mRNA levels of FasL but not Fas. The mRNA expression levels of FasL and Fas in SCC12 cells treated with subamolide B (0~20 μM) for 24 h were monitored by semiquantitative RT-PCR analysis. β-actin was used as the loading control. (c) Effects of subamolide B on the mRNA expression levels of TRAIL, DR4, and DR5. SCC12 cells treated with subamolide B as described in (b) were subjected to quantitative real-time RT-PCR analysis for the mRNA expression levels of TRAIL and the two cognate TRAIL receptors DR4 and DR5. It is noted that subamolide B decreases the mRNA levels of TRAIL while increasing those of DR5 and barely modulates DR4 expression. The mRNA levels are presented as the ratio of genes-in-interest mRNA levels normalized to TATA box-binding protein (TBP) mRNA levels after subamolide B treatment to that of drug-untreated controls. **; ***.
