Hui-Yi Lin

Extract of lotus leaf ( Nelumbo nucifera ) and its active constituent catechin with insulin secretagogue activity.

The effect of lotus leaf ( Nelumbo nucifera Gaertn.) on diabetes is unclear. We hypothesized that lotus leaf can regulate insulin secretion and blood glucose levels. The in vitro and in vivo effects of lotus leaf methanolic extract (NNE) on insulin secretion and hyperglycemia were investigated. NNE increased insulin secretion from β cells (HIT-T15) and human islets. NNE enhanced the intracellular calcium levels in β cells. NNE could also enhance phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2 and protein kinase C (PKC), which could be reversed by a PKC inhibitor. The in vivo studies showed that NNE possesses the ability to regulate blood glucose levels in fasted normal mice and high-fat-diet-induced diabetic mice. Furthermore, the in vitro and in vivo effects of the active constituents of NNE, quercetin, and catechin, on glucose-induced insulin secretion and blood glucose regulation were evaluated. Quercetin did not affect insulin secretion, but catechin significantly and dose-dependently enhanced insulin secretion. Orally administered catechin significantly reversed the glucose intolerance in high-fat-diet-induced diabetic mice. These findings suggest that NNE and its active constituent catechin are useful in the control of hyperglycemia in non-insulin-dependent diabetes mellitus through their action as insulin secretagogues.

Pu-erh Tea Attenuates Hyperlipogenesis and Induces Hepatoma Cells Growth Arrest through Activating AMP-Activated Protein Kinase (AMPK) in Human HepG2 Cells

In the present study, we successively extracted the pu-erh raw tea with methanol (PR-1), chloroform (PR-2), ethyl acetate (PR-3), n-butanol (PR-4), and water (PR-5). Among these extracts, PR-3 extract contained ingredients with the most effective hypolipidemic potential and was further purified by column chromatography. Moreover, chronic administration of PR-3 provoked a significant reduction in levels of serum triglyceride and low-density lipoprotein (LDL) in rats. Our study demonstrated that fraction 5 from the PR-3 extract (PR-3-5s) showed a hypolipidemic effect in human hepatoma HepG2 cells. PR-3-5s decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) by stimulating AMP-activated protein kinase (AMPK) through the LKB1 pathway. Moreover, PR-3-5s blocked the progression of the cell cycle at the G1 phase by inducing p53 expression and in turn upregulating p21 expression.

Gallic acid inhibits the migration and invasion of A375.S2 human melanoma cells through the inhibition of matrix metalloproteinase-2 and Ras

Melanoma is one of the most common cancers worldwide and its incidence has been increasing over the past few decades. Gallic acid (GA) can inhibit the growth of human cancer cells in vitro and in vivo. However, there is no available information to address the effects of GA on migration and invasion of human skin cancer cells. Matrix metalloproteinases (MMPs), zinc-dependent proteolytic enzymes, play an important role in the invasion, metastasis, and angiogenesis of cancer cells. Therefore, MMPs are one of the targets for agents to suppress and that could inhibit the migration and invasion of cancer cells. GA affected the viable A375.S2 cells by propidium iodide exclusion and flow cytometric analysis. Cell migration and invasion were investigated by Boyden chamber assay and we also determined the levels of protein and mRNA expression cell migration and invasion by gelatin zymography, western blotting, and real-time PCR assays. In this study, we examined the influence of GA on the protein levels and gene expression of MMP-2 and MMP-9 and in-vitro migration and invasiveness of human melanoma cells. GA decreases the MMPs and associated signal pathway protein and MMPs mRNA levels in A375.S2 human melanoma cells. Our findings suggest that GA has antimetastatic potential by decreasing invasiveness of cancer cells. Moreover, this action of GA was involved in the Ras, p-ERK signaling pathways resulting in inhibition of MMP-2 in A375.S2 human melanoma cells. These data, therefore, provide evidence for the role of GA as a potential cancer chemotherapeutic agent, which can markedly inhibit the invasive capacity of melanoma cells.

Inhibition of epidermal growth factor receptor signaling by Saussurea involucrata, a rare traditional Chinese medicinal herb, in human hormone-resistant prostate cancer PC-3 cells.

Prostate carcinoma is the most frequently diagnosed malignancy and the second leading cause of death of men in the United States. To date, no effective therapeutic treatment allows abrogation of the progression of prostate cancer to more invasive forms. In this study, we identified Saussurea involucrata Kar. et Kir., a rare traditional Chinese medicinal herb, as a potential agent for androgen-independent prostate cancer patients and investigated its biological mechanism as an antineoplastic agent. S. involucrata caused a concentration- and time-dependent inhibition of cell proliferation in human hormone-resistant prostate cancer PC-3 cells. Moreover, in vitro studies in a panel of several types of human cancer cell lines revealed that S. involucrata inhibited cell proliferation with high potency. To evaluate the bioactive compounds, we successively extracted the S. involucrata with fractions of methanol (SI-1), ethyl acetate (SI-2), n-butanol (SI-3), and water (SI-4). Among these extracts, SI-2 contains the most effective bioactivity. SI-2 treatment resulted in significant time-dependent growth inhibition together with G1 phase cell cycle arrest and apoptosis in PC3 cells. In addition, SI-2 treatment strongly induced p21WAF1/CIP and p27KIP1 expression, independent of the p53 pathway, and downregulated expression of cyclin D1 and cyclin-dependent kinase 4 (CDK4). SI-2 treatment increased levels of Bax, cytochrome c, activated caspase-3, and active caspase-9 and decreased Bcl-2 expression level. One of the major targets for the therapy in prostate cancer can be epidermal growth factor receptor (EGFR). SI-2 markedly reduced phosphorylation of EGFR and inhibited activation of AKT and STAT3. Moreover, p.o. administration of SI-2 induced a dose-dependent inhibition of PC-3 tumor growth in vivo. In summary, our study identifies S. involucrata as an effective inhibitor of EGFR signaling in human hormone-resistant prostate cancer PC-3 cells. We suggest that S. involucrata could be developed as an agent for the management of EGFR-positive human cancers.

Osthole Suppresses Fatty Acid Synthase Expression in HER2-Overexpressing Breast Cancer Cells through Modulating Akt/mTOR Pathway

While fatty acid synthase (FASN) has been shown to be expressed in many human solid tumors, FASN has also been identified in preneoplastic lesions. HER2, which has also been identified in preneoplastic breast lesions, has been shown to upregulate FASN expression. Osthole, an active constituent isolated from the fruit of Cnidium monnieri (L.) Cusson, a traditional Chinese medicine, was found to be effective in suppressing FASN expression in HER2-overexpressing breast cells. Osthole preferentially inhibited proliferation and induced apoptosis in HER2-overexpressing cancer cells. Moreover, osthole inhibited the phosphorylation of Akt and mTOR. The use of Akt-overexpression revealed that the modulation of Akt and mTOR was required for osthole-induced FASN suppression. Finally, we showed that osthole could enhance paclitaxel-induced cytotoxicity in HER2-overexpressing cancer cells. These results suggested that osthole has the potential to advance as chemopreventive or chemotherapeutic agent for cancers that overexpress HER2.

Rhein Induces Apoptosis in Human Breast Cancer Cells

Human breast cancers cells overexpressing HER2/neu are more aggressive tumors with poor prognosis, and resistance to chemotherapy. This study investigates antiproliferation effects of anthraquinone derivatives of rhubarb root on human breast cancer cells. Of 7 anthraquinone derivatives, only rhein showed antiproliferative and apoptotic effects on both HER2-overexpressing MCF-7 (MCF-7/HER2) and control vector MCF-7 (MCF-7/VEC) cells. Rhein induced dose- and time-dependent manners increase in caspase-9-mediated apoptosis correlating with activation of ROS-mediated activation of NF-κB- and p53-signaling pathways in both cell types. Therefore, this study highlighted rhein as processing anti-proliferative activity against HER2 overexpression or HER2-basal expression in breast cancer cells and playing important roles in apoptotic induction of human breast cancer cells.

Design, Synthesis, and Preclinical Evaluation of New 5,6- (or 6,7-) Disubstituted-2-(fluorophenyl)quinolin-4-one Derivatives as Potent Antitumor Agents

Our previous exploration of 2-phenylquinolin-4-ones (2-PQs) has led to an anticancer drug candidate 2-(2-fluorophenyl)-6,7-methylenedioxyquinolin-4-one monosodium phosphate (CHM-1-P-Na). In order to develop additional new drug candidates, novel 2-PQs were designed, synthesized, and evaluated for cytotoxic activity. Most analogues, including 1b, 2a,b, 3a,b, 4a,b, and 5a,b, exhibited significant inhibitory activity (IC(50) of 0.03-8.2 μM) against all tested tumor cell lines. As one of the most potent analogue, 2-(3-fluorophenyl)-5-hydroxy-6-methoxyquinolin-4-one (3b) selectively inhibited 14 out of 60 cancer cell lines in a National Cancer Institute (NCI) evaluation. Preliminary mechanism of action study suggested that 3b had a significant effect on the tyrosine autophosphorylation of insulin-like growth factor-1 receptor (IGF-1R). Safety pharmacology profiling of 3b showed no significant effect on normal biological functions of most enzymes tested. Furthermore, sodium 2-(3-fluorophenyl)-6-methoxy-4-oxo-1,4-dihydroquinolin-5-yl phosphate (15), the monophosphate of 3b, exceeded the activity of doxorubicin and was comparable to CHM-1-P-Na in a Hep3B xenograft nude mice model. In summary, 15 is a promising clinical candidate and is currently under preclinical study.

Demethoxycurcumin Modulates Prostate Cancer Cell Proliferation via AMPK-Induced Down-regulation of HSP70 and EGFR

Curcumin (Cur), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) are major forms of curcuminoids found in the rhizomes of turmeric. This study examined the effects of three curcuminoid analogues on prostate cancer cells. The results revealed that DMC demonstrated the most efficient cytotoxic effects on prostate cancer PC3 cells. DMC activated AMPK and in turn decreased the activity and/or expression of lipogenic enzymes, such as fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC). AICAR, an AMPK activator, and DMC down-regulated heat shock protein (HSP) 70 and increased the activity of the pro-apoptotic effector, caspase-3. In addition, DMC sustained epidermal growth factor receptor (EGFR) activation by suppressing the phosphatases PP2a and SHP-2. DMC also increased the interaction between EGFR and Cbl and induced the tyrosine phosphorylation of Cbl. The results suggest that DMC may have antitumor effects on prostate cancer cells via AMPK-induced down-regulation of HSP70 and EGFR.

Lotus Leaf (Nelumbo nucifera) and its Active Constituents Prevent Inflammatory Responses in Macrophages via JNK/NF-κB Signaling Pathway

Inflammation is a serious health issue worldwide that induces many diseases, such as inflammatory bowel disease (IBD), sepsis, acute pancreatitis and lung injury. Thus, there is a great deal of interest in new methods of limiting inflammation. In this study, we investigated the leaves of Nelumbo nucifera Gaertn, an aquatic perennial plant cultivated in eastern Asia and India, in anti-inflammatory pharmacological effects in the murine macrophage cell line RAW264.7. Results showed that lipopolysaccharide (LPS) increased the protein expression of inducible nitric oxide synthase (iNOS) and COX-2, as well as the mRNA expression and level of IL-6 and TNF-α, while NNE significantly reduced these effects of LPS. LPS also induced phospho-JNK protein expression. The JNK-specific inhibitor SP600125 decreased the proteins expression of phospho-JNK, iNOS, COX-2, and the mRNAs expression and levels of IL-6 and TNF-α. Further, NNE reduced the protein expression of phospho-JNK. LPS was also found to promote the translocation of NF-κB from the cytosol to the nucleus and to decrease the expression of cytosolic IκB. NNE and SP600125 treatment recovered the LPS-induced expression of NF-κB and IκB. While phospho-ERK and phospho-p38 induced by LPS, could not be reversed by NNE. To further investigate the major components of NNE in anti-inflammatory effects, we determined the quercetin and catechin in inflammatory signals. Results showed that quercetin and catechin significantly decreased the proteins expression of iNOS, COX-2 and phospho-JNK. Besides, the mRNAs and levels of IL-6 and TNF-α also decreased by quercetin and catechin treatment in LPS-induced RAW264.7 cells. These results showed that NNE and its major components quercetin and catechin exhibit anti-inflammatory activities by inhibiting the JNK- and NF-κB-regulated pathways and could therefore be an useful anti-inflammatory agent.

Synthesis of 1-benzyl-3-(5-hydroxymethyl-2-furyl)selenolo[3,2-c]pyrazole derivatives as new anticancer agents

As part of our continuing search for potential anticancer drug candidates among YC-1 analogs, 1, 3-disubstituted selenolo[3,2-c]pyrazole derivatives were synthesized and evaluated for their cytotoxicity against NCI-H226 non-small cell lung cancer and A-498 renal cancer cell lines. Significant cytotoxicity was observed in 3-(5-hydroxymethyl-2-furyl) derivatives (2, 33, 36 and 37). Among them, compound 2 was found to have the most potent activity. The mode of action of compound 2 seems to differ from those of the 175 anticancer agents listed in NCIs standard database and resembles that of YC-1. Thus, we recommend that compound 2 should be developed further as new drug candidate for treatment of non-small cell lung cancer and renal cancer.