Targets and mechanisms of berberine, a natural drug with potential to treat cancer with special focus on breast cancer

Berberine, a natural compound, suppresses Hedgehog signaling pathway activity and cancer growth

Background

Berberine (BBR), a natural alkaloid compound, is used as a non-prescription drug in China for treating diarrhea and gastroenteritis. Many studies have revealed that BBR possesses anticancer effect. However, the molecular mechanisms underlying its anticancer action is far from being fully elucidated. This study is aimed to determine the effect of BBR on the hedgehog (Hh) activity and the growth of cancers addiction to Hh activity.

Methods

The Hh activity was determined by dual luciferase assays and quantitative RT-PCR analyses. The growth inhibition of BBR on medulloblastoma which was obtained from ptch+/−;p53−/− mice was analyzed by 5-bromo-2-deoxyuridine (Brdu) assays and by allografting the medulloblastoma into nude mice. The data were statistically analyzed by one-way analysis of variance (ANOVA), and multiple comparison between the groups was performed using Dunnett’s method.

Results

In this study, we found that BBR significantly inhibited the Hh pathway activity. Meanwhile, we observed that BBR failed to affect the transcriptional factors activities provoked by tumor necrosis factor-α (TNF-α) and Prostaglandin E2 (PGE2), thus suggesting its unique property against Hh pathway activity. Further studies revealed that BBR inhibited the Hh pathway activity by potentially targeting the critical component Smoothened (Smo) and most likely shared the same binding site on Smo with cyclopamine, a classical Smo inhibitor. Finally, we demonstrated that BBR obviously suppressed the Hh-dependent medulloblastoma growth in vitro and in vivo.

Conclusion

Collectively, our study uncovered a novel molecular mechanism responsible for the anticancer action of BBR, thus opening the way for the usage of BBR for therapeutics of cancers addiction to aberrant Hh pathway activity.

Berberine regulates neurite outgrowth through AMPK-dependent pathways by lowering energy status

As a widely used anti-bacterial agent and a metabolic inhibitor as well as AMP-activated protein kinase (AMPK) activator, berberine (BBR) has been shown to cross the blood-brain barrier. Its efficacy has been investigated in various disease models of the central nervous system. Neurite outgrowth is critical for nervous system development and is a highly energy-dependent process regulated by AMPK-related pathways. In the present study, we aimed to investigate the effects of BBR on AMPK activation and neurite outgrowth in neurons. The neurite outgrowth of primary rat cortical neurons at different stages of polarization was monitored after exposure of BBR. Intracellular energy level, AMPK activation and polarity-related pathways were also inspected. The results showed that BBR suppressed neurite outgrowth and affected cytoskeleton stability in the early stages of neuronal polarization, which was mediated by lowered energy status and AMPK activation. Liver kinase B1 and PI3K-Akt-GSK3β signaling pathways were also involved. In addition, mitochondrial dysfunction and endoplasmic reticulum stress contributed to the lowered energy status induced by BBR. This study highlighted the knowledge of the complex activities of BBR in neurons and corroborated the significance of energy status during the neuronal polarization.

PIK3CA rs7640662 (C/G) single nucleotide polymorphism lacks association with breast cancer cases in Persians

Phosphatidylinositol-3-kinase (PI3K) is a group of enzymes involved in cellular growth, proliferation, differentiation, cell motility, intracellular trafficking, and survival that play very important roles in developing breast cancer. PIK3CA is a gene that encodes α catalytic subunit of this enzyme. A common polymorphism of PIK3CA, rs7640662 (C/G), was analyzed, and its association to breast cancer cases was determined. In this study, DNA was extracted from peripheral blood samples of 278 women suffering from breast cancer and 128 healthy women. Tetra-primer amplification refractory mutation system polymerase chain reaction (T-ARMS-PCR) method was performed to genotype rs7640662. P values and ODD ratios were measured using SPSS. P value less than 0.05 and ODD ratios more than 1 were considered as significant. All ODD ratios were less than 1, and P values were more than 0.05 showing that rs7640662 (C/G) and breast cancer are not significantly associated. However, the genotypes observed in the Persian population, as an ancient population living in the Middle East, was significantly different from the genotypes reported by HapMap for Asian populations. As a conclusion, rs7640662 was not associated with the risk of breast cancer in a Persian population; however, it was observed that heterozygote (GC) is the most common genotypes in both case and control samples.

Tetrahydroberberine, a pharmacologically active naturally occurring alkaloid

Tetrahydroberberine (systematic name: 9,10-dimethoxy-5,8,13,13a-tetrahydro-6H-benzo[g][1,3]benzodioxolo[5,6-a]quinolizine), C20H21NO4, a widely distributed naturally occurring alkaloid, has been crystallized as a racemic mixture about an inversion center. A bent conformation of the molecule is observed, with an angle of 24.72 (5)° between the arene rings at the two ends of the reduced quinolizinium core. The intermolecular hydrogen bonds that play an apparent role in crystal packing are 1,3-benzodioxole -CH2···OCH3 and -OCH3···OCH3 interactions between neighboring molecules.

Curcumin inhibits oral squamous cell carcinoma SCC-9 cells proliferation by regulating miR-9 expression

Curcumin, a phytochemical derived from the rhizome of Curcuma longa, has shown anticancer effects against a variety of tumors. In the present study, we investigated the effects of curcumin on the miR-9 expression in oral squamous cell carcinoma (OSCC) and explored the potential relationships between miR-9 and Wnt/β-catenin pathway in curcumin-mediated OSCC inhibition in vitro. As the results shown, the expression levels of miR-9 were significantly lower in clinical OSCC specimens than those in the adjacent non-tumor tissues. Furthermore, our results indicated that curcumin inhibited OSCC cells (SCC-9 cells) proliferation through up-regulating miR-9 expression, and suppressing Wnt/β-catenin signaling by increasing the expression levels of the GSK-3β, phosphorylated GSK-3β and β-catenin, and decreasing the cyclin D1 level. Additionally, the up-regulation of miR-9 by curcumin in SCC-9 cells was significantly inhibited by delivering anti-miR-9 but not control oligonucleotides. Downregulation of miR-9 by anti-miR-9 not only attenuated the growth-suppressive effects of curcumin on SCC-9 cells, but also re-activated Wnt/β-catenin signaling that was inhibited by curcumin. Therefore, our findings would provide a new insight into the use of curcumin against OSCC in future.

A gene expression signature-based approach reveals the mechanisms of action of the Chinese herbal medicine berberine

Berberine (BBR), a traditional Chinese herbal medicine, was shown to display anticancer activity. In this study, we attempted to provide a global view of the molecular pathways associated with its anticancer effect through a gene expression-based chemical approach. BBR-induced differentially expressed genes obtained from the Gene Expression Omnibus (GEO) at the National Center for Biotechnology Information (NCBI) were analyzed using the Connectivity Map (CMAP) database to compare similarities of gene expression profiles between BBR and CMAP compounds. Candidate compounds were further analyzed using the Search Tool for Interactions of Chemicals (STITCH) database to explore chemical-protein interactions. Results showed that BBR may inhibit protein synthesis, histone deacetylase (HDAC), or AKT/mammalian target of rapamycin (mTOR) pathways. Further analyses demonstrated that BBR inhibited global protein synthesis and basal AKT activity, and induced endoplasmic reticulum (ER) stress and autophagy, which was associated with activation of AMP-activated protein kinase (AMPK). However, BBR did not alter mTOR or HDAC activities. Interestingly, BBR induced the acetylation of α-tubulin, a substrate of HDAC6. In addition, the combination of BBR and SAHA, a pan-HDAC inhibitor, synergistically inhibited cell proliferation and induced cell cycle arrest. Our results provide novel insights into the mechanisms of action of BBR in cancer therapy.