Baicalein suppresses HER2-mediated malignant transformation of HER2-overexpressing ovarian cancer cells by downregulating HER2 gene expression.

The upregulation of the HER2 oncogene is associated with a variety of human cancers and is associated with poor prognosis. Baicalein is reported to have anti-tumor activity, but the molecular mechanism of this effect in HER2-positive cancer cells has not been studied. In this study, our data showed that baicalein can inhibit the proliferation and transformation potential of ovarian cancer cells overexpressing HER2. Baicalein treatment caused a dose-dependent inhibition of HER2 gene expression at the transcriptional level. Baicalein acted on ovarian cancer cells overexpressing HER2 to downregulate the PI3K/Akt signaling pathway downstream of HER2 and inhibit the expression or activity of downstream targets, such as VEGF and cyclin D1 and MMP2. Oral administration of baicalein supplemented with a pharmaceutical excipient significantly inhibited the growth of HER2-overexpressing ovarian SKOV-3 cancer xenografts in mice. These results suggest that downregulation of HER2 gene expression by baicalein at the transcriptional level contributes to inhibit the in vitro and in vivo proliferation and HER2-mediated malignant transformation of HER2-overexpressing ovarian cancer cells.

Baicalein Induces G2/M Cell Cycle Arrest Associated with ROS Generation and CHK2 Activation in Highly Invasive Human Ovarian Cancer Cells.

Ovarian cancer is a lethal gynecological cancer because drug resistance often results in treatment failure. The CHK2, a tumor suppressor, is considered to be an important molecular target in ovarian cancer due to its role in DNA repair. Dysfunctional CHK2 impairs DNA damage-induced checkpoints, reduces apoptosis, and confers resistance to chemotherapeutic drugs and radiation therapy in ovarian cancer cells. This provides a basis for finding new effective agents targeting CHK2 upregulation or activation to treat or prevent the progression of advanced ovarian cancer. Here, the results show that baicalein (5,6,7-trihydroxyflavone) treatment inhibits the growth of highly invasive ovarian cancer cells, and that baicalein-induced growth inhibition is mediated by the cell cycle arrest in the G2/M phase. Baicalein-induced G2/M phase arrest is associated with an increased reactive oxygen species (ROS) production, DNA damage, and CHK2 upregulation and activation. Thus, baicalein modulates the expression of DNA damage response proteins and G2/M phase regulatory molecules. Blockade of CHK2 activation by CHK2 inhibitors protects cells from baicalein-mediated G2/M cell cycle arrest. All the results suggest that baicalein has another novel growth inhibitory effect on highly invasive ovarian cancer cells, which is partly related to G2/M cell cycle arrest through the ROS-mediated DNA breakage damage and CHK2 activation. Collectively, our findings provide a molecular basis for the potential of baicalein as an adjuvant therapeutic agent in the treatment of metastatic ovarian cancer.

Dual down-regulation of EGFR and ErbB2 by berberine contributes to suppression of migration and invasion of human ovarian cancer cells.

The overexpression of EGFR and/or ErbB2 occurs frequently in ovarian cancers and is associated with poor prognosis. The purpose of this study was to examine the anticancer effects and molecular mechanisms of berberine on human ovarian cancer cells with different levels of EGFR and/or ErbB2. We found that berberine reduced the motility and invasiveness of ovarian cancer cells. Berberine depleted both EGFR and ErbB2 in ovarian cancer cells. Furthermore, berberine suppressed the activation of the EGFR and ErbB2 downstream targets cyclin D1, MMPs, and VEGF by down-regulating the EGFR-ErbB2/PI3K/Akt signaling pathway. The berberine-mediated inhibition of MMP-2 and MMP-9 activity could be rescued by co-treatment with EGF. Finally, we demonstrated that berberine induced ErbB2 depletion through ubiquitin-mediated proteasome degradation. In conclusion, the suppressive effects of berberine on the ovarian cancer cells that differ in the expression of EGFR and ErbB2 may be mediated by the dual depletion of EGFR and/or ErbB2.

A rational approach for cancer stem-like cell isolation and characterization using CD44 and prominin-1(CD133) as selection markers.

The availability of adequate cancer stem cells or cancer stem-like cell (CSC) is important in cancer study. From ovarian cancer cell lines, SKOV3 and OVCAR3, we induced peritoneal ascites tumors in immunodeficient mice. Among the cells (SKOV3.PX1 and OVCAR3.PX1) from those tumors, we sorted both CD44 and CD133 positive cells (SKOV3.PX1_133+44+, OVCAR3.PX1_133+44+), which manifest the characteristics of self-renewal, multi-lineage differentiation, chemoresistance and tumorigenicity, those of cancer stem-like cells (CSLC). Intraperitoneal transplantation of these CD44 and CD133 positive cells resulted in poorer survival in the engrafted animals. Clinically, increased CD133 expression was found in moderately and poorly differentiated (grade II and III) ovarian serous cystadenocarcinomas. The ascites tumor cells from human ovarian cancers demonstrated more CD133 and CD44 expressions than those from primary ovarian or metastatic tumors and confer tumorigenicity in immunodeficient mice. Compared to their parental cells, the SKOV3.PX1_133+44+ and OVCAR3.PX1_133+44+ cells uniquely expressed 5 CD markers (CD97, CD104, CD107a, CD121a, and CD125). Among these markers, CD97, CD104, CD107a, and CD121a are significantly more expressed in the CD133+ and CD44+ double positive cells of human ovarian ascites tumor cells (Ascites_133+44+) than those from primary ovarian or metastatic tumors. The cancer stem-like cells were enriched from 3% to more than 70% after this manipulation. This intraperitoneal enrichment of cancer stem-like cells, from ovarian cancer cell lines or primary ovarian tumor, potentially provides an adequate amount of ovarian cancer stem-like cells for the ovarian cancer study and possibly benefits cancer therapy.

A Chinese herbal medicine, jia-wei-xiao-yao-san, prevents dimethylnitrosamine-induced hepatic fibrosis in rats.

Jia-wei-xiao-yao-san (JWXYS) is a traditional Chinese herbal medicine that is widely used to treat neuropsychological disorders. Only a few of the hepatoprotective effects of JWXYS have been studied. The aim of this study was to investigate the hepatoprotective effects of JWXYS on dimethylnitrosamine- (DMN-) induced chronic hepatitis and hepatic fibrosis in rats and to clarify the mechanism through which JWXYS exerts these effects. After the rats were treated with DMN for 3 weeks, serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) levels were significantly elevated, whereas the albumin level decreased. Although DMN was continually administered, after the 3 doses of JWXYS were orally administered, the SGOT and SGPT levels significantly decreased and the albumin level was significantly elevated. In addition, JWXYS treatment prevented liver fibrosis induced by DMN. JWXYS exhibited superoxide-dismutase-like activity and dose-dependently inhibited DMN-induced lipid peroxidation and xanthine oxidase activity in the liver of rats. Our findings suggest that JWXYS exerts antifibrotic effects against DMN-induced chronic hepatic injury. The possible mechanism is at least partially attributable to the ability of JWXYS to inhibit reactive-oxygen-species-induced membrane lipid peroxidation.

Ganoderma tsugae Extract Inhibits Growth of HER2-Overexpressing Cancer Cells via Modulation of HER2/PI3K/Akt Signaling Pathway.

Ganoderma, also known as Lingzhi or Reishi, has been used for medicinal purposes in Asian countries for centuries. It is a medicinal fungus with a variety of biological properties including immunomodulatory and antitumor activities. In this study, we investigated the molecular mechanisms by which Ganoderma tsugae (GT), one of the most common species of Ganoderma, inhibits the proliferation of HER2-overexpressing cancer cells. Here, we show that a quality assured extract of GT (GTE) inhibited the growth of HER2-overexpressing cancer cells in vitro and in vivo and enhanced the growth-inhibitory effect of antitumor drugs (e.g., taxol and cisplatin) in these cells. We also demonstrate that GTE induced cell cycle arrest by interfering with the HER2/PI3K/Akt signaling pathway. Furthermore, GTE curtailed the expression of the HER2 protein by modulating the transcriptional activity of the HER2 gene and the stability/degradation of the HER2 protein. In conclusion, this study suggests that GTE may be a useful adjuvant therapeutic agent in the treatment of cancer cells that highly express HER2.

Berberine, an isoquinoline alkaloid, inhibits the metastatic potential of breast cancer cells via Akt pathway modulation.

Berberine (BBR) is a natural alkaloid with significant antitumor activities against many types of cancer cells. In this study, we investigated the molecular mechanisms by which BBR repressed the metastatic potential of breast cancer cells. BBR was found to downregulate the enzymatic activities and expression levels of matrix metalloproteinases 2 and 9 (MMP2 and MMP9, respectively). The BBR-mediated suppression of MMP2 and MMP9 involved the inhibition of the Akt/nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1) signaling pathways. Furthermore, BBR repressed the expression of the Akt protein by modulating the mRNA expression level and protein degradation of Akt. In conclusion, this study suggests that BBR can reduce the metastatic potential of highly metastatic breast cancer cells and may be a useful adjuvant therapeutic agent in the treatment of breast cancer by targeting the Akt pathway.

Triptolide Transcriptionally Represses HER2 in Ovarian Cancer Cells by Targeting NF-κB.

Triptolide (TPL) inhibits the proliferation of a variety of cancer cells and has been proposed as an effective anticancer agent. In this study, we demonstrate that TPL downregulates HER2 protein expression in oral, ovarian, and breast cancer cells. It suppresses HER2 protein expression in a dose- and time-dependent manner. Transrepression of HER2 promoter activity by TPL is also observed. The interacting site of TPL on the HER2 promoter region is located between -207 and -103 bps, which includes a putative binding site for the transcription factor NF-κB. Previous reports demonstrated that TPL suppresses NF-κB expression. We demonstrate that overexpression of NF-κB rescues TPL-mediated suppression of HER2 promoter activity and protein expression in NIH3T3 cells and ovarian cancer cells, respectively. In addition, TPL downregulates the activated (phosphorylated) forms of HER2, phosphoinositide-3 kinase (PI3K), and serine/threonine-specific protein kinase (Akt). TPL also inhibits tumor growth in a mouse model. Furthermore, TPL suppresses HER2 and Ki-67 expression in xenografted tumors based on an immunohistochemistry (IHC) assay. These findings suggest that TPL transrepresses HER2 and suppresses the downstream PI3K/Akt-signaling pathway. Our study reveals that TPL can inhibit tumor growth and thereby may serve as a potential chemotherapeutic agent.

Magnolol down-regulates HER2 gene expression, leading to inhibition of HER2-mediated metastatic potential in ovarian cancer cells.

Overexpression of the HER2 oncogene contributes to tumor cell invasion, metastasis and angiogenesis and correlates with poor prognosis. Magnolol has been reported to exhibit anti-tumor activities. However, the molecular mechanism of action of magnolol has not been investigated in HER2-positive cancer cells. Therefore, we examined the anti-cancer effects of magnolol on HER2-overexpressing ovarian cancer cells. Magnolol treatment caused a dose-dependent inhibition of HER2 gene expression at the transcriptional level, potentially in part through suppression of NF-κB activation. Treatment of HER2-overexpressing ovarian cancer cells with magnolol down-regulated the HER2 downstream PI3K/Akt signaling pathway, and suppressed the expression of downstream target genes, vascular endothelial growth factor (VEGF), matrix metalloproteinase 2 (MMP2) and cyclin D1. Consistently, magnolol-mediated inhibition of MMP2 activity could be prevented by co-treatment with epidermal growth factor. Migration assays revealed that magnolol treatment markedly reduced the motility of HER2-overexpressing ovarian cancer cells. Furthermore, magnolol-induced apoptosis in HER2-overexpressing ovarian cancer cells was characterized by the up-regulation of cleaved poly(ADP-ribose) polymerase (PARP) and activated caspase 3. These findings suggest that magnolol may act against HER2 and its downstream PI3K/Akt/mTOR-signaling network, thus resulting in suppression of HER2-mediated transformation and metastatic potential in HER2-overexpressing ovarian cancers. These results provide a novel mechanism to explain the anti-cancer effect of magnolol.

Growth suppression of HER2-overexpressing breast cancer cells by berberine via modulation of the HER2/PI3K/Akt signaling pathway.

Berberine (BBR) is a natural alkaloid with significant antitumor activities against many types of cancer cells. This study investigated the molecular mechanisms by which BBR suppresses the growth of HER2-overexpressing breast cancer cells. The results show that BBR induces G1-phase cell cycle arrest by interfering with the expression of cyclins D1 and E and that it induces cellular apoptosis through the induction of a mitochondria/caspase pathway. The data also indicate that BBR inhibits cellular growth and promotes apoptosis by down-regulating the HER2/PI3K/Akt signaling pathway. Furthermore, it is also shown that a combination of taxol and BBR significantly slows the growth rate of HER2-overexpressing breast cancer cells. In conclusion, this study suggests that BBR could be a useful adjuvant therapeutic agent in the treatment of HER2-overexpressing breast cancer.

Seeing red: the origin of grain pigmentation in US weedy rice.

Weedy forms of crop species infest agricultural fields worldwide and are a leading cause of crop losses, yet little is known about how these weeds evolve. Red rice (Oryza sativa), a major weed of cultivated rice fields in the US, is recognized by the dark-pigmented grain that gives it its common name. Studies using neutral molecular markers have indicated a close relationship between US red rice and domesticated rice, suggesting that the weed may have originated through reversion of domesticated rice to a feral form. We have tested this reversion hypothesis by examining molecular variation at Rc, the regulatory gene responsible for grain pigmentation differences between domesticated and wild rice. Loss-of-function mutations at Rc account for the absence of proanthocyanidin pigments in cultivated rice grains, and the major rc domestication allele has been shown to be capable of spontaneous reversion to a functional form through additional mutations at the Rc locus. Using a diverse sample of 156 weedy, domesticated and wild Oryzas, we analysed DNA sequence variation at Rc and its surrounding 4 Mb genomic region. We find that reversion of domestication alleles does not account for the pigmented grains of weed accessions; moreover, we find that haplotypes characterizing the weed are either absent or very rare in cultivated rice. Sequences from genomic regions flanking Rc are consistent with a genomic footprint of the rc selective sweep in cultivated rice, and they are compatible with a close relationship of red rice to Asian Oryzas that have never been cultivated in the US.

Ganoderma tsugae extract inhibits expression of epidermal growth factor receptor and angiogenesis in human epidermoid carcinoma cells: In vitro and in vivo.

We examined the anti-angiogenic effects of Ganoderma tsugae methanol extract (GTME) on human epidermoid carcinoma A-431 cells. Our data indicate that GTME inhibits the expression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in vitro and in vivo, and also inhibits the capillary tube formation of human umbilical vein endothelial cells (HUVECs). We also show that the suppression of VEGF expression by GTME can be restored by treatment with EGF. These results suggest that GTME inhibits VEGF expression via the suppression of EGFR expression, resulting in the downregulation of VEGF secretion from epidermoid carcinoma A-431 cells. These findings reveal a novel role for G. tsugae in inhibiting EGFR and VEGF expression, which are important for tumor angiogenesis and growth. Thus, GTME may provide a potential therapeutic approach for anti-tumor treatment.

Ganoderma tsugae extracts inhibit colorectal cancer cell growth via G(2)/M cell cycle arrest.

ETHNOPHARMACOLOGICAL RELEVANCE: Ganoderma, known as Lingzhi or Reishi, has been traditionally administered throughout Asia for centuries as a cancer treatment and for other medicinal purposes. AIM OF THE STUDY: To investigate the inhibitory activity and explore the molecular mechanisms of anti-tumor effect on colorectal cancer cells in vitro and in vivo as well as to test the side effects of Ganoderma tsugae. MATERIALS AND METHODS: Methanol fraction was obtained from dried fruiting bodies of Ganoderma. TLC and HPLC were performed to differentiate and confirm the identification of different species as well as to quantify the bioactive molecules in methanol extracts of Ganoderma species. MTT and Trypan blue exclusion assay as well as tumorigenesis study were used to assess the anti-tumor effect in vitro and in vivo. Using flow cytometry and Western Blots, we examined further the molecular mechanisms of anti-tumor effect. Finally, biochemical and hematological profiles and pathological examinations were used to evaluate the safety. RESULTS: The Ganoderma tsugae extracts inhibit colorectal cancer cell proliferation caused by accumulating cells in G(2)/M phase, and it may be through downregulation of cyclin A and B1 and upregulation of p21 and p27. Tumorigenesis study in nude mice revealed the extracts caused tumor shrinkage. Additionally, safety assay showed Ganoderma tsugae extracts caused no significant side effects in an animal model. CONCLUSIONS: This study provides molecular evidence that Ganoderma tsugae extracts exert anti-tumor effects both in vitro and in vivo on colorectal adenocarcinoma cells by inducing G(2)/M cell cycle arrest. More importantly, no significant physiological changes resulting from treatment with Ganoderma tsugae extracts were observed in the animal model. Therefore, these data provide new insights into the possible therapeutic use of Ganoderma tsugae for treating colorectal cancer.

Evidence on the molecular basis of the Ac/ac adaptive cyanogenesis polymorphism in white clover (Trifolium repens L).

White clover is polymorphic for cyanogenesis, with both cyanogenic and acyanogenic plants occurring in nature. This chemical defense polymorphism is one of the longest-studied and best-documented examples of an adaptive polymorphism in plants. It is controlled by two independently segregating genes: Ac/ac controls the presence/absence of cyanogenic glucosides; and Li/li controls the presence/absence of their hydrolyzing enzyme, linamarase. Whereas Li is well characterized at the molecular level, Ac has remained unidentified. Here we report evidence that Ac corresponds to a gene encoding a cytochrome P450 of the CYP79D protein subfamily (CYP79D15), and we describe the apparent molecular basis of the Ac/ac polymorphism. CYP79D orthologs catalyze the first step in cyanogenic glucoside biosynthesis in other cyanogenic plant species. In white clover, Southern hybridizations indicate that CYP79D15 occurs as a single-copy gene in cyanogenic plants but is absent from the genomes of ac plants. Gene-expression analyses by RT-PCR corroborate this finding. This apparent molecular basis of the Ac/ac polymorphism parallels our previous findings for the Li/li polymorphism, which also arises through the presence/absence of a single-copy gene. The nature of these polymorphisms may reflect white clover's evolutionary origin as an allotetraploid derived from cyanogenic and acyanogenic diploid progenitors.

Downregulation of HER2 by RIG1 involves the PI3K/Akt pathway in ovarian cancer cells.

Interferon-gamma (IFN-gamma) is known to downregulate HER2 oncoprotein (p185(HER2) or briefly p185) in prostate cancer cells. We demonstrate that the IFN-gamma-induced retinoid-inducible gene 1 (RIG1) acts as a transrepressor of p185. Furthermore, we exhibit that RIG1 downregulates the activated (phosphorylated) form of p185 and phosphoinositide-3 kinase (PI3K)/serine/threonine-specific protein kinase (Akt) and the mammalian target of rapamycin (mTOR), downstream substrates of HER2. We also elucidate that heregulin (HRG) specifically restores the activation of p185 and Akt after their activities are reduced by RIG1. Additionally, expression of vascular endothelial growth factor (VEGF) increases through the HER2- and Akt/mTOR-signaling pathways, indicating that VEGF is downregulated by RIG1 within the cell. These findings suggest that RIG1 plays a role in IFN-gamma-mediated therapy by downregulating p185 and its downstream PI3K/Akt/mTOR/VEGF-signaling pathway. These results may provide a new therapeutic mechanism for the clinical use of IFN-gamma and RIG1.

Linker-modified triamine-linked acridine dimers: synthesis and cytotoxicity properties in vitro and in vivo.

The preparation and cytotoxicity properties of a series of N(epsilon)-substituted triamine-linked acridine dimers are described. Most acridine dimer derivatives reveal highly potent in vitro cytotoxicity properties and DNA binding activity. Several acridine dimers were selected to study their action in vivo. These acridine dimers have demonstrated a narrow safe margin, as has adriamycin, but higher maximum tolerate dose (MTD) in comparison with that of adriamycin in ICR mice. The acridine dimers also demonstrated various anit-COLO 205 solid tumor activities in vivo. Compound 1 has shown the most potent solid tumor inhibition.