Harnessing traditional Chinese medicine to improve cancer therapy: issues for future development

Gut microbiota, a new frontier to understand traditional Chinese medicines

As an important component of complementary and alternative medicines, traditional Chinese medicines (TCM) are gaining more and more attentions around the world because of the powerful therapeutic effects and less side effects. However, there are still some doubts about TCM because of the questionable TCM theories and unclear biological active compounds. In recent years, gut microbiota has emerged as an important frontier to understand the development and progress of diseases. Together with this trend, an increasing number of studies have indicated that drug molecules can interact with gut microbiota after oral administration. In this context, more and more studies pertaining to TCM have paid attention to gut microbiota and have yield rich information for understanding TCM. After oral administration, TCM can interact with gut microbiota: (1) TCM can modulate the composition of gut microbiota; (2) TCM can modulate the metabolism of gut microbiota; (3) gut microbiota can transform TCM compounds. During the interactions, two types of metabolites can be produced: gut microbiota metabolites (of food and host origin) and gut microbiota transformed TCM compounds. In this review, we summarized the interactions between TCM and gut microbiota, and the pharmacological effects and features of metabolites produced during interactions between TCM and gut microbiota. Then, focusing on gut microbiota and metabolites, we summarized the aspects in which gut microbiota has facilitated our understanding of TCM. At the end of this review, the outlooks for further research of TCM and gut microbiota were also discussed.

Compound Fuling Granule Suppresses Ovarian Cancer Development and Progression by disrupting mitochondrial function, galactose and fatty acid metabolism

Our previous studies have demonstrated that the compound fuling granule (CFG), a traditional Chinese medicine, suppresses ovarian cancer cell growth, migration and metastasis. However, the underlying mechanisms remain to be fully elucidated. In this study, we found that CFG could induce mitochondrial fragmentation, mitochondrial membrane potential reduction and cytochrome c release in ovarian SKOV3 cancer cells. In addition, both metabolomics and transcriptomics approaches were applied to illustrate the systemic mechanism of CFG on ovarian cancer formation and progression. To this end, we established two tumor-bearing mice models with subcutaneous injection or tail intravenous injection. Functionally, administration of CFG suppresses in situ tumor growth and distant lung metastasis. Subsequently, gas chromatography-mass spectrometry (GC-MS) was applied to determine the metabolic alterations among the plasma samples from these in vivo models. In the subcutaneous injection model, 26 distinguishable metabolites were identified and 12 metabolic pathways were reprogrammed. Meanwhile, 19 metabolites involved in 7 metabolic pathways showed significant differences in the tail intravenous injection model. Importantly, integrative metabolomics and transcriptomics analysis showed these metabolites were highly associated with galactose metabolism and fatty acid metabolism. This study suggests that CFG may suppress ovarian cancer cell proliferation and metastasis by regulating mitochondrion-related energy metabolisms.

Overcoming chemoresistance in prostate cancer with Chinese medicine Tripterygium wilfordii via multiple mechanisms

A leading cause of cancer chemotherapy failure is chemoresistance, which often involves multiple mechanisms. Chinese medicines (CM) usually contain multiple components which could potentially target many mechanisms simultaneously and may offer an advantage over single compounds that target one mechanism at a time. The purpose of this study was to investigate the chemosensitizing effect (CE) of a specific CM, Tripterygium wilfordii (TW), on prostate cancer cells resistant to docetaxel (Dtx) and identify the potential mechanisms. The CE of TW (in combination with Dtx) was evaluated in two Dtx resistant prostate cancer cell lines (PC3-TxR and DU145-TxR) and the efficacy of the combination for resistant PC3-TxR tumor was investigated using a xenograft mouse model. For mechanistic study, the inhibitory effect of TW on P-glycoprotein activity was assessed. In addition, novel gene targets of TW were identified using DNA microarray and quantitative PCR. Results showed that TW induced a CE of 8 and >38 folds in PC3-TxR and DU145-TxR cells, respectively with Dtx IC50 reversed back to that of the sensitive parent cells. An optimum dose of TW+Dtx significantly retarded tumor growth in mice compared to TW or Dtx alone. TW inhibited P-glycoprotein activity and induced a significant gene expression changes in genes related to angiogenesis, cell cycle regulation and differentiation. Our in vitro and in vivo studies demonstrate that TW in combination with Dtx was able to overcome the chemoresistance and suppress resistant prostate tumor growth via multi-mechanisms.

Euphorbia fischeriana Steud inhibits malignant melanoma via modulation of the phosphoinositide-3-kinase/Akt signaling pathway

Euphorbia fischeriana Steud, a traditional Chinese medicine, has been shown to inhibit the growth of various cancers by the induction of apoptosis and cell cycle arrest. The purpose of the present study was to investigate the association between the phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway and the inhibitory effect of Euphorbia fischeriana Steud on the growth and metastasis of melanoma B16 cells in vitro, and the underlying mechanisms. MTT assay results indicated that Euphorbia fischeriana Steud inhibited the growth of B16 cells in a time- and dose-dependent manner. Flow cytometric analysis revealed that Euphorbia fischeriana Steud markedly induced apoptosis of the B16 cells, with arrest at the G0/G1 phase of the cell cycle. In addition, in a Transwell assay Euphorbia fischeriana Steud significantly suppressed the migration of B16 cells. Western blot analysis revealed that the expression levels of phosphatase and tensin homolog (PTEN) were upregulated, and the phosphorylation of Akt was downregulated, which resulted in inhibition of the PI3K/Akt signaling pathway and the eventual suppression of its downstream targets, such as matrix metalloproteinase-2 mRNA, in B16 cells. The results demonstrated that Euphorbia fischeriana Steud inhibited the growth and migration of B16 cells, possibly via modulation of the PI3K/Akt signaling pathway and upregulation of PTEN expression levels, in addition to downregulation of p-Akt expression. The aforementioned findings suggest that Euphorbia fischeriana Steud may have broad therapeutic applications in the treatment of malignant melanoma.

Prosapogenin A induces apoptosis in human cancer cells in vitro via inhibition of the STAT3 signaling pathway and glycolysis

Signal transducer and activator of transcription 3 (STAT3) is considered to be an oncogene. Blocking STAT3 signaling may induce growth arrest and apoptosis in different types of tumors. Cancer cells utilize the glycolytic pathway to maintain cell growth even when adequate oxygen is present. Glycolysis inhibition is a potential therapeutic modality. In the present study, the effects of Prosapogenin A (PSA) from the traditional Chinese medicine, Veratrum, on apoptosis, the STAT3 signaling pathway and glycometabolism in cancer cells were investigated. The results indicated that PSA induced growth inhibition and apoptosis in HeLa, HepG2 and MCF-7 cells. PSA inhibited the STAT3 signaling pathway and modulated the expression of glycometabolism-related genes. The results indicate that the inhibition of the STAT3 signaling and glycometabolism pathways contributes to the PSA-mediated apoptosis of HeLa, HepG2 and MCF-7 cells.

Discovery of molecular mechanisms of traditional Chinese medicinal formula Si-Wu-Tang using gene expression microarray and connectivity map

To pursue a systematic approach to discovery of mechanisms of action of traditional Chinese medicine (TCM), we used microarrays, bioinformatics and the “Connectivity Map” (CMAP) to examine TCM-induced changes in gene expression. We demonstrated that this approach can be used to elucidate new molecular targets using a model TCM herbal formula Si-Wu-Tang (SWT) which is widely used for women's health. The human breast cancer MCF-7 cells treated with 0.1 µM estradiol or 2.56 mg/ml of SWT showed dramatic gene expression changes, while no significant change was detected for ferulic acid, a known bioactive compound of SWT. Pathway analysis using differentially expressed genes related to the treatment effect identified that expression of genes in the nuclear factor erythroid 2-related factor 2 (Nrf2) cytoprotective pathway was most significantly affected by SWT, but not by estradiol or ferulic acid. The Nrf2-regulated genes HMOX1, GCLC, GCLM, SLC7A11 and NQO1 were upreguated by SWT in a dose-dependent manner, which was validated by real-time RT-PCR. Consistently, treatment with SWT and its four herbal ingredients resulted in an increased antioxidant response element (ARE)-luciferase reporter activity in MCF-7 and HEK293 cells. Furthermore, the gene expression profile of differentially expressed genes related to SWT treatment was used to compare with those of 1,309 compounds in the CMAP database. The CMAP profiles of estradiol-treated MCF-7 cells showed an excellent match with SWT treatment, consistent with SWT's widely claimed use for women's diseases and indicating a phytoestrogenic effect. The CMAP profiles of chemopreventive agents withaferin A and resveratrol also showed high similarity to the profiles of SWT. This study identified SWT as an Nrf2 activator and phytoestrogen, suggesting its use as a nontoxic chemopreventive agent, and demonstrated the feasibility of combining microarray gene expression profiling with CMAP mining to discover mechanisms of actions and to identify new health benefits of TCMs.