Bucidarasin A suppresses the proliferation and metastasis of HCC by targeting the FAK and STAT3 pathways.

Hepatocellular carcinoma (HCC) is a significant global health concern, with high rates of morbidity and mortality. Bucidarasin A, a natural diterpenoid, has been shown to exert notable cytotoxic effects across a range of tumor cell lines. However, the underlying mechanisms responsible for this cytotoxicity remain unclear. In this study, we sought to elucidate the antitumor mechanisms of bucidarasin A, a natural diterpenoid derived from Casearia graveolens, with a particular focus on its effects on HCC. Furthermore, we employed surface plasmon resonance (SPR), molecular docking, and cellular thermal shift assay (CETSA) to gain further insight into the target protein of bucidarasin A. Our findings revealed that bucidarasin A exhibited pronounced cytotoxicity towards HepG2 cells. In vitro analysis indicated that bucidarasin A interrupted the cell cycle at the S phase and inhibited the proliferation and metastasis of HepG2 cells by modulating the FAK and STAT3 signaling pathways. Moreover, in vivo studies demonstrated that bucidarasin A not only exhibited antitumor effects but also impeded neovascularization, a finding that was corroborated by SPR interactions between vascular endothelial growth factor (VEGF) and bucidarasin A. This research substantiated that bucidarasin A, a clerodane diterpenoid, held promise as a therapeutic candidate against HCC, showcasing substantial antitumor efficacy both in vitro and in vivo through direct targeting of the STAT3 and FAK signaling pathways.

Jolkinolide B synergistically potentiates the antitumor activity of GPX4 inhibitors via inhibiting TrxR1 in cisplatin-resistant bladder cancer cells.

Glutathione peroxidase 4 (GPX4) is a promising anticancer therapeutic target; however, the application of GPX4 inhibitors (GPX4i) is limited owing to intrinsic or acquired drug resistance. Hence, understanding the mechanisms underlying drug resistance and discovering molecules that can overcome drug resistance are crucial. Herein, we demonstrated that GPX4i killed bladder cancer cells by inducing lipid reactive oxygen species-mediated ferroptosis and apoptosis, and cisplatin-resistant bladder cancer cells were also resistant to GPX4i, representing a higher half-maximal inhibitory concentration value than that of parent bladder cancer cells. In addition, thioredoxin reductase 1 (TrxR1) overexpression was responsible for GPX4i resistance in cisplatin-resistant bladder cancer cells, and inhibiting TrxR1 restored the sensitivity of these cells to GPX4i. In vitro and in vivo studies revealed that Jolkinolide B (JB), a natural diterpenoid and previously identified as a TrxR1 inhibitor, potentiated the antiproliferative efficacy of GPX4i (RSL3 and ML162) against cisplatin-resistant bladder cancer cells. Furthermore, GPX4 knockdown and inhibition could augment JB-induced paraptosis and apoptosis. Our results suggest that inhibiting TrxR1 can effectively improve GPX4 inhibition-based anticancer therapy. A combination of JB and GPX4i, which is well-tolerated and has several anticancer mechanisms, may serve as a promising therapy for treating bladder cancer.

Jolkinolide B sensitizes bladder cancer to mTOR inhibitors via dual inhibition of Akt signaling and autophagy.

The monotherapy of mTOR inhibitors (mTORi) in cancer clinical practice has achieved limited success due to the concomitant activation of compensatory pathways, such as Akt signaling and cytoprotective autophagy. Thus, the combination of mTORi and the inhibitors of these pro-survival pathways has been considered a promising therapeutic strategy. Herein, we report the synergistic effects of a natural anti-cancer agent Jolkinolide B (JB) and mTORi (temsirolimus, rapamycin, and everolimus) for the effective treatment of bladder cancer. A mechanistic study revealed that JB induced a dual inhibition of Akt feedback activation and cytoprotective autophagy, potentiating the anti-proliferative efficacy of mTORi in both PTEN-deficient and cisplatin-resistant bladder cancer cells. Meanwhile, mTORi augmented the pro-apoptotic and pro-paraptotic effects of JB by reinforcing JB-activated endoplasmic reticulum stress and MAPK pathways. These synergistic mechanisms were related to cellular reactive oxygen species accumulation. Our study suggests that dual inhibition of Akt feedback activation and cytoprotective autophagy is an effective strategy in mTORi-based therapy, and JB + mTORi combination associated with multiple anti-cancer mechanisms and good tolerance in mouse models may serve as a promising treatment for bladder cancer.