Bruceine A inhibited breast cancer proliferation and metastasis by inducing autophagy via targeting PI3K-AKT signaling pathway

Although there have been significant advances in cancer treatment, the urgent need to inhibit breast cancer metastasis remained unmet. Bruceine A (BA) is a natural compound extracted from Bruceae Fructus and has long been recognized to have antitumor effects with high safety and biocompatibility. However, the mechanisms and/or targets of BA for metastatic breast cancer treatment are still not fully elucidated. In this study, we systematically investigated the effects of BA on inhibition of breast cancer metastasis and its underlying mechanisms. We found that, in addition to its cytotoxic effects, BA significantly inhibited the invasion and migration capabilities of two types of breast cancer cell lines (MDA-MB-231 and MCF-7) while concurrently promoting apoptosis in these cells. Further mechanistic studies revealed that, by targeting the canonical PI3K-AKT signaling pathway, BA initiated autophagy of both types of breast cancer cell lines in vitro. In vivo results further confirmed the in vitro findings, manifested by shrinkage of size and weight of breast tumor as well as initiation of autophagy (indicated by upregulation of LC3I/II) through targeting PI3K-AKT pathway on mice model. These data collectively demonstrated the potential of BA in antimetastasis of breast cancer cells, suggesting its future clinical transformation in metastatic breast cancer therapy.

Bruceine A: Suppressing metastasis via MEK/ERK pathway and invoking mitochondrial apoptosis in triple-negative breast cancer

Triple-negative breast cancer (TNBC), as the most aggressive subtype of breast cancer, presents a scarcity of miraculous drugs in suppressing its proliferation and metastasis. Bruceine A (BA) is a functional group-rich quassin compound with extensive and distinctive pharmacological activities. Within the present study, we investigated the capabilities of BA in suppressing TNBC proliferation and metastasis as well as its potential mechanisms. The results displayed that BA dramatically repressed the proliferation of MDA-MB-231 and 4T1 cells with corresponding IC50 values of 78.4 nM and 524.6 nM, respectively. Concurrently, BA arrested cells in G1 phase by downregulating cycle-related proteins Cyclin D1 and CDK4. Furthermore, BA distinctly induced mitochondrial dysfunction as manifested by diminished mitochondrial membrane potential, elevated reactive oxygen species generation, minimized ATP production, and Caspase-dependent activation of the mitochondrial apoptosis pathway. Additionally, BA restrained the invasion and metastasis of TNBC cells by repressing MMP9 and MMP2 expression. Intriguingly, after pretreatment with MEK activator C16-PAF, the inhibitory effect of BA on MEK/ERK pathway was notably diminished, while the proliferation suppression and metastasis repression exerted by BA were all strikingly curtailed. Molecular docking illustrated that BA potently combined with residues on the MEK1 protein with the presence of diverse intermolecular interactions. Ultimately, BA effectively suppressed tumor growth in the 4T1 xenograft tumor model with no detectable visceral toxicity in the high-dose group and, astonishingly, repressed tumor metastasis in the 4T1-luc lung metastasis model. Collectively, our study demonstrates that BA is a promising chemotherapeutic agent for treating TNBC and suppressing lung metastasis.

Bruceine A induces cell growth inhibition and apoptosis through PFKFB4/GSK3β signaling in pancreatic cancer

Pancreatic cancer is one of the most aggressive cancers with a poor prognosis and 5-year low survival rate. In the present study, we report that bruceine A, a quassinoid found in Brucea javanica (L.) Merr. has a strong antitumor activity against human pancreatic cancer cells both in vitro and in vivo. Human proteome microarray reveals that 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 4 (PFKFB4) is the candidate target of bruceine A and both fluorescence measurement and microscale thermophoresis suggest bruceine A binds to PFKFB4. Bruceine A suppresses glycolysis by inhibiting PFKFB4, leading to cell cycle arrest and apoptosis in MIA PaCa-2 cells. Furthermore, glycogen synthase kinase-3 β (GSK3β) is identified as a downstream target of PFKFB4 and an PFKFB4-interacting protein. Moreover, bruceine A induces cell growth inhibition and apoptosis through GSK3β, which is dysregulated in pancreatic cancer and closely related to the prognosis. In all, these findings suggest that bruceine A inhibits human pancreatic cancer cell growth via PFKFB4/GSK3β-mediated glycolysis, and it may serve as a potent agent for curing human pancreatic cancer.

A novel P38α MAPK activator Bruceine A exhibits potent anti-pancreatic cancer activity

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Bruceine A displays potent anti-pancreatic cancer activity in vitro and in vivo.

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Phosphoproteomic analyses identify bruceine A induces phosphorylation of p38α MAPK.

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Octet system and microscale thermophoresis reveal p38α MAPK has high affinity for bruceine A.

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Molecular simulations illustrate determinants of bruceine A binding with p38α MAPK.

Pancreatic cancer remains one of the cancers with the poorest prognosis bearing an overall 5-year survival rate of about 5%. Efficient new chemotherapic drugs are still highly desired. Here, bruceine A, a quassinoid identified from the dried fruits of Brucea javanica (L.) Merr., displayed the most potent anti-proliferation activity against pancreatic cancer in vitro and in vivo. Phosphoproteomic analysis revealed p38α MAPK phosphorylation was involved in bruceine A’s action in MIA PaCa-2 cells. Utilizing fortebio octet system and microscale thermophoresis, we found p38α MAPK had high affinity for bruceine A. Molecular docking and molecular dynamic simulations showed that bruceine A widely bound to residues (Leu171, Ala172, Met179, Thr180, Val183) in P-loop of p38α MAPK. Key determinants of bruceine A binding with P-loop of p38α MAPK were 19-C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]>O, 22-CH₃, 32-CH₃, and 34-CH₃. Taken together, our findings demonstrate that bruceine A binds directly to p38α MAPK, which can be used to probe the role of p38α MAPK phosphorylation in pancreatic cancer progression, and as a novel lead compound for pancreatic cancer therapy.