Auriculasin induces mitochondrial oxidative stress and drives ferroptosis by inhibiting PI3K/Akt pathway in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) accounts for the majority of cases of lung cancer with poor outcomes. Auriculasin is a prenylated isoflavone abundant in the root of F. philippinensis with multiple pharmacological effects, including anticancer role. However, its roles in NSCLC remain largely unknown. NSCLC A549 cells were treated with auriculasin in vitro, and used to induce xenograft models. Cell viability was detected via CCK-8 assay. Mitochondrial oxidative stress was analyzed by JC-1 staining, ROS staining, and levels of MDA, SOD and GSH. Ferroptosis was assessed via iron content, and levels of ACSL4, PTGS2, FSP1 and GPX4. The phosphorylation levels of PI3K and Akt were measured by western blot. Auriculasin reduced NSCLC cell viability. Auriculasin promoted mitochondrial oxidative stress by reducing mitochondrial membrane potential, SOD and GSH levels, and enhancing ROS and MDA contents. In addition, auriculasin induced ferroptosis via increasing iron, ACSL4 and PTGS3 levels, and decreasing FSP1 and GPX4 levels. Furthermore, the potential targets of auriculasin in NSCLC were enriched in PI3K/Akt signaling. Auriculasin blunted PI3K/Akt pathway activation by blocking the phosphorylation. Activated PI3K/Akt signaling by activator 740Y-P reversed the effects of auriculasin on mitochondrial oxidative stress and ferroptosis. Finally, auriculasin reduced NSCLC cell growth in xenograft models. Auriculasin facilitates mitochondrial oxidative stress and induces ferroptosis through inhibiting PI3K/Akt pathway in NSCLC.

Pharmacological properties of extracts and prenylated isoflavonoids from the fruits of Osage orange (Maclura pomifera (Raf.) C.K.Schneid.).

Osage orange trees (Maclura pomifera (Raf.) C.K.Schneid.) are distributed worldwide, particularly in south-east states of the USA. They produce large quantities of strong yellow fruits, bigger than oranges, but these fruits are inedible, with an acid milky juice which is little consumed by birds and insects. Extracts prepared from Osage orange fruits (hedge apple) have revealed a range of pharmacological properties of interest in human and veterinary medicine. In addition, Osage orange extracts can be used in agriculture and aquaculture, and as dyeing agent for the textile industry. Extracts contain potent antioxidant compounds, notably the isoflavonoids pomiferin and auriculasin, together with other terpenoids and flavonoids. The structural characteristics and pharmacological properties of the major prenylated isoflavones isolated from M. pomifera are discussed here, with a focus on the two phenolic compounds osajin and warangalone, and the two catechol analogues pomiferin and auriculasin. The mechanisms at the origin of their potent antioxidant and anti-inflammatory effects are presented, notably inhibition of xanthine oxidase, phosphodiesterase 5A and kinases such as RKS2 and kRAS. Osajin and auriculasin display marked anticancer properties, owing to their ability to inhibit tumor cell proliferation, migration and tumor angiogenesis. Different molecular mechanisms are discussed, including osajin­copper complexation and binding to quadruplex DNA. An overview of the mechanism of action of the prenylated isoflavones from Osage orange is presented, with the objective to promote their knowledge and to raise opportunities to better exploit the fruits of Osage orange, abundant but largely neglected at present.

Auriculasin enhances ROS generation to regulate colorectal cancer cell apoptosis, ferroptosis, oxeiptosis, invasion and colony formation.

Colorectal cancer (CRC) is one of the most common malignant tumors in the digestive system, and Chinese herbal medicine plays an important role in tumor treatment. The in-depth study of auriculasin isolated from Flemingia philippinensis showed that auriculasin promoted reactive oxygen species (ROS) generation in a concentration-dependent manner; when ROS scavenger NAC was added, the effects of auriculasin in promoting ROS generation and inhibiting cell viability were blocked. Auriculasin induced CRC cell apoptosis, led to mitochondrial shrinkage, and increased the intracellular accumulation of Fe2+ and MDA. When auriculasin and NAC were added simultaneously, the levels of apoptosis, Fe2+ and MDA returned to the control group levels, indicating that auriculasin activated apoptosis and ferroptosis by inducing ROS generation. In addition, auriculasin promoted the expression of Keap1 and AIFM1, but significantly reduced the phosphorylation level of AIFM1, while NAC significantly blocked the regulation of Keap1 and AIFM1 by auriculasin, which indicates that auriculasin can also induce oxeiptosis through ROS. When Z-VAD-FMK, Ferrostatin-1, Keap1 siRNA, PGAM5 siRNA and AIFM1 siRNA were added respectively, the inhibitory effect of auriculasin on cell viability was significantly weakened, indicating that auriculasin inhibits cell viability by inducing apoptosis, ferroptosis and oxeiptosis. Auriculasin also inhibited the invasion and clone forming ability of CRC cells, while NAC blocked the above effects of auriculasin. Therefore, auriculasin can promote CRC cell apoptosis, ferroptosis and oxeiptosis by inducing ROS generation, thereby inhibiting cell viability, invasion and clone formation, indicating that auriculasin has a significant antitumor effect.

Discovery of direct inhibitor of KRAS oncogenic protein by natural products: a combination of pharmacophore search, molecular docking, and molecular dynamic studies.

BACKGROUND AND PURPOSE: Aberrant signaling by oncogenic RAS proteins occurs in almost all human tumors. One of the promising strategies to overcome such cancers is the inhibition of KRAS protein, a subtype of RAS family involved in cell growth, differentiation, and apoptosis, through preventing its effector, SOS1, from being attached to the protein. EXPERIMNTAL APPROACH: Herein, a virtual screening process was performed using pharmacophore search, molecular docking, and molecular dynamic simulations. A pharmacophore model was created to indicate essential features for a KRAS inhibitor and used for screening the National Cancer Institution (NCI) database to retrieve similar compounds to the pharmacophore model with more than 70% similarity. Chosen compounds were then docked into KRAS and four compounds were selected based on the highest binding scores. Next, a similarity search was done in the whole PubChem database to increase the number of potential inhibitors. The filtered compounds were docked again into KRAS and three of them were selected for molecular dynamic simulation. FINDINGS / RESULTS: Compounds 1a, 2d, and 3a can inhibit SOS-iKRASG12D interaction due to the higher number of interactions with the protein. Moreover, they achieved the equilibrium faster than the approved inhibitor. CONCLUSION AND IMPLICATIONS: Auriculasin, a polyphenol flavonoid, can be considered as a potential inhibitor of SOS1-KRAS interaction. This compound seems to be a stronger anticancer than 9LI, a known inhibitor of KRAS, due to its better docking scores. Moreover, this compound can be an appropriate candidate to be formulated as an oral drug.

Auriculasin sensitizes primary prostate cancer cells to TRAIL-mediated apoptosis through up-regulation of the DR5-dependent pathway.

Primary prostate cancer cells frequently develop resistance toward chemotherapy as well as most chemotherapeutics have been reported to induce undesirable cytotoxicity in normal cells. In this study, we performed sensitizing activity analysis of auriculasin (AC) to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in RC-58T/h/SA#4 primary prostate cancer cells without significant cytotoxicity in RWPE-1 prostate epithelial cells. Combined treatment with AC and TRAIL at optimal concentrations resulted in tumor-specific apoptotic cell death in RC-58T/h/SA#4 cells, characterized by DNA fragmentation, accumulation of apoptotic cell population, and nuclear condensation. Compared to single treatment with AC or TRAIL, co-treatment with AC and TRAIL significantly increased expression of Bax, cleaved PARP, AIF, endo G, and cytochrome c but decreased expression of phosphorylation of AKT and mammalian target of rapamycin (mTOR), phosphoinositide 3-kinase (PI3K), Bcl-2 and caspases-9, -8, -3, and -10. The sensitizing effect of AC to TRAIL was well correlated with inhibition of death receptor 5 (DR5) CHOP, and p53 expression. Moreover, pre-treatment with a chimeric blocking antibody for DR5 effectively reduced AC-TRAIL-induced cell death and apoptosis-related protein expression. These results suggest that non-toxic concentrations of AC sensitize TRAIL-resistant primary prostate cancer cells to TRAIL-mediated apoptosis via up-regulation of DR5 and downstream signaling pathways.

Effects of auriculasin on vascular endothelial growth factor (VEGF)-induced angiogenesis via regulation of VEGF receptor 2 signaling pathways in vitro and in vivo.

Angiogenesis plays an important role in various pathological conditions such as cancer via excessive delivery of oxygen and nutrients. Recent studies have demonstrated that understanding the molecular basis of natural agents in angiogenesis is critical for the development of promising cancer therapeutics. In this study, auriculasin, an active component from Flemingia philippinensis, was found to exert strong anti-angiogenesis activity. Treatment with auriculasin suppressed proliferation of human umbilical vein endothelial cells (HUVECs) by modulating expression of Bcl-2, Bcl-XL, and vascular endothelial growth factor (VEGF). Further, auriculasin inhibited VEGF-induced chemotactic migration, invasion, and capillary-like structure formation of endothelial cells. In addition, auriculasin abrogated VEGF-induced vascular network formation around rat aortic rings as well as blocked accumulation of hemoglobin, endothelial cells and VEGF in the Matrigel plug of C57BL/6 mice. The inhibitory effect of auriculasin on angiogenesis was well correlated with inhibition of VEGF receptor 2 (VEGFR2) activation as well as phosphorylation of intracellular downstream protein kinases of VEGFR2 containing Akt, mammalian target of rapamycin (mTOR), phosphoinositide 3-kinase (PI3K), p-38, extracellular signal-related kinase (ERK), and Src. Taken together, this study reports that auriculasin potently inhibits angiogenesis by modulating VEGFR2-related signaling pathways, which further validates its great potential in clinical applications.

Auriculasin-induced ROS causes prostate cancer cell death via induction of apoptosis.

Recent studies have demonstrated that natural agents targeting the accumulation of reactive oxygen species (ROS) that selectively kill, leaving normal cells undamaged, can suppress prostate cancer. Here, we show that auriculasin, derived from Flemingia philippinensis, induces significant cell death and apoptosis via ROS generation in prostate cancer cells. Auriculasin treatment resulted in selective apoptotic cell death in LNCaP prostate cancer cells, characterized by DNA fragmentation, accumulation of sub-G1 cell population, cleavage of poly (ADP-ribose) polymerase (PARP), regulation of Bax/Bcl-2 ratio, increase of cytosolic apoptosis-inducing factor (AIF) and endonuclease G (EndoG), in addition to inhibiting tumor growth in a xenograft mouse model. Interestingly, auriculasin-induced apoptosis did not result in caspase-3, -8, and -9 activations. We found that auriculasin treatment decreased phosphorylation of AKT/mTOR/p70s6k in a dose- and time-dependent manner. Further, cellular ROS levels increased in LNCaP cells treated with auriculasin and blocking ROS accumulation with ROS scavengers resulted in inhibition of auriculasin-induced PARP cleavage, AIF increase, upregulation of Bax/Bcl-2 ratio, and decrease in AKT/mTOR phosphorylation. Taken together, these data suggest that auriculasin targets ROS-mediated caspase-independent pathways and suppresses PI3K/AKT/mTOR signaling, which leads to apoptosis and decreased tumor growth.